• May 2019
• April 2019
• March 2019
• February 2019
• January 2019
• December 2018
• November 2018
• October 2018
• May 2018
• April 2018
• March 2018
• February 2018
• January 2018
• December 2017
• November 2017
• May 2017
• April 2017
• March 2017
• November 2016

Time and date: Tuesday June 2nd @15:00 (CET)

Speaker: Marta Losada (New York University Abu Dhabi)

Title: "Impact of LHC Higgs physics and EDMs on Baryogenesis in the Standard Model EFT with dim 6 terms

Abstract: In this talk I will present the study of Higgs boson observables at the LHC and their impact on electroweak baryogenesis in the context of Standard Model effective field theory with the inclusion of dimension 6 operators of Higgs and fermion fields. I will also discuss how these new terms can generate an electric dipole moment of leptons and thus add further constraints to produce the baryon asymmetry. I present the main results when considering a single fermion flavor term or for combinations of two flavors. For each case, the results of the identification of which observables constrain more severely the new terms and the interplay of the complementary constraints to identify viable regions of parameter space is also presented.

Slides: files/HIDDEN-062020.pdf

Speaker:  Jure Zupan (Cincinnati U and CERN)

Abstract:

Solving the flavor problem of the Standard Model with a simple U(1)_H flavor symmetry naturally leads to an axion that solves the strong CP problem and constitutes a viable Dark Matter candidate. In this framework, the ratio of the axion mass and its coupling to photons is related to the SM fermion masses and predicted within a small range, as a direct result of the observed hierarchies in quark and charged lepton masses. The same hierarchies determine the axion couplings to fermions, making the framework very predictive and experimentally testable by future axion and precision flavor experiments.

To see a video recording of the session, click here. Slides are available here.

Speaker:  Christoph Weniger (University of Amsterdam)

Abstract

I will summarize our current knowledge about the GeV bulge emission. A leading astrophysical interpretation of the emission is that it comes from thousands of hitherto unknown millisecond pulsars (MSPs) in the Galactic bulge.  I will discuss in some detail a wavelet fluctuation analysis of the gamma-ray emission from the inner Galaxy, which we did recently to test this hypothesis.  We found strong support for the MSP hypothesis.  However, systematic uncertainties remain large, and a clear detection of the bulge MSPs in radio observations will be necessary for a solid confirmation.  If as significant number of MSPs is found in the Galactic bulge, this will reduce, and possibly eliminate, the need for more exotic explanations in terms of dark matter annihilation.  I will close with our plans to search for these sources in radio, using MeerKAT (planned for 2018) and telescopes like the GBT and the VLA.

Speaker:  Prof. Ann Nelson (Washington University, Seatle)

Abstract:  I discuss CP violating oscillations of neutral baryons into anti baryons, and propose an experimentally allowed scenario where some heavy flavored baryons oscillate at rates which are within a few orders of magnitude of their lifetimes, while the flavor structure of the baryon violation suppresses neutron oscillations and baryon violating nuclear decays to experimentally allowed rates. I describe a scenario for producing such baryons in the early universe via the out of equilibrium decays of a neutral particle, after the hadronization temperature but before nucleosynthesis, and the prospects for baryogenesis.

Speaker:  Prof. Gia Dvali (NYU and LMU Munich)

Abstract: We discuss a generic  source of chiral symmetry breaking  in the standard model fermions in form of gravitational anomaly and its role in generating neutrino masses without the need of other sources.

Speaker:  Prof. Jonathan Feng (University of California, Irvine)

Abstract:  Recently a 6.8σ anomaly has been reported in the decays of excited 8Be nuclei, which can be resolved by postulating the existence of a new weakly-coupled, 17 MeV boson. I will discuss the experimental results; new physics explanations, focusing on dark forces and gauged B and L symmetries; and prospects for future experiments.

Presenter:  Prof. Bhupal Dev (Washington U., St. Louis)

Abstract: A dark matter (DM) halo intervening along the line of sight of a gravitational wave (GW) signal could induce a change in the speed of GW. We show that this change of speed is observable with the current LIGO sensitivity for a class of ultralight DM models which could form a Bose-Einstein condensate (BEC) in the early universe and behave as a single coherent wave instead of individual particles in galaxies. Hence, we propose to use the deviation in the speed of GW as a new probe of the BEC DM parameter space. With a multi-messenger approach to GW astronomy and/or with extended sensitivity to lower GW frequencies, the entire BEC DM parameter space can be effectively probed by our new method in the near future.

Speaker:  Prof. Osamu Yasuda (Tokyo Metropolitan University)

Abstract: In this work we present a scenario in which a nonstandard interaction in neutrino propagation can explain the three major tensions in the neutrino oscillation data at present. These tensions are: (i) a non-zero best-fit value of the non-standard oscillation parameters in the the global analysis of the solar and KamLAND data which rules out the standard oscillation scenario at  90% C.L, (ii) the measurement of the non-maximal value of theta23 by Nova which excludes  maximal mixing at 2.5 sigma and (iii)  the discrepancy in the theta13 measurement by T2K and  reactors at 90% C.L  Our results show that all these three  anomalies can be explained if one assumes the existence of non-standard interactions in neutrino propagation  in the case of normal hierarchy.  In our scenario the phase of $\epsilon_{e\tau}$ is zero and the most favorable value of the Dirac CP phase is approximately 255 degrees.

Date and time: December 4th, 2017 15:00 CET

Speaker: T. Schwetz (Karlsruhe)

Title: Update on sterile neutrino oscillations at the eV scale

Abstract: In this talk I critically review the hints in favour of neutrino mass states at the eV scale. In particular I discuss the status of the sterile neutrino explanations of the reactor and LSND anomalies, focusing on recent developments. While the situation of the reactor anomaly remains ambiguous and explanation of LSND in terms of oscillations becomes exceedingly disfavoured by the non-observation of muon neutrino disappearance.

Date and time: Tuesday November 28th, 2017 @ 15:00

Speaker: Matteo Viel (INFN Trieste)

Title: "New results from intergalactic medium structures on dark matter nature"

Abstract: I will review the current status of Lyman-alpha forest cosmology for testing the dark matter nature with particular emphasis on fuzzy dark matter and thermal candidates

Date and time: Tuesday November 14th, 2017 @ 15:30

Speaker: M. Shaposhnikov (EPFL Lausanne)

Abstract: I will confront different ways the scale invariance can be broken in quantum field theory and discuss quantum scale invariant effective theories of particle physics and gravity and their relevance to the hierarchy problem

Date and time: Tuesday October 17th @ 2:30pm (CET)

Speaker: Phillip Barbeau (Duke University)

Abstract: The coherent elastic scattering of neutrinos off nuclei was first predicted 43 years ago with the realization of the neutral weak current. The predicted cross-section is the largest of any known neutrino interactions; however, the process has remained undetected until recently due to the daunting experimental challenges. I will report on the first observation of this process, newly announced by the COHERENT collaboration—an effort which has major contributions from a large team at Duke and the Triangle Universities Nuclear Laboratory. I will also discuss the importance that coherent neutrino scattering plays in many areas of physics, including searches for Dark Matter, nuclear astrophysics, searches for new physics beyond the Standard Model, and even applications to nuclear safeguards and security.

Date: Tuesday May 23rd @ 3pm (CET)

Speaker: R. Alonso (CERN)

Title: Lepton Universality Violation in Rare B-meson Decays; a New Local Symmetry?

Abstract: We review the experimental evidence, recently reinforced by LHCb, of Lepton Universality Violation in rare B-meson decays. On the theory side, in view of a combined $4\sigma$ tension with the Standard Model prediction, the pursuit of a New Physics explanation is in full steam. After a brief overview of the possibilities explored in the literature, we discuss a type of $U(1)$ local horizontal (i.e. flavour) symmetry in our personal quest for beauty behind the madness.

Date and Time: Tuesday April 25th @ 15pm CET

Speaker: Nazila Mahmoudi (U. Lyon)

Abstract: I will discuss the recent so-called LHCb anomalies, deviations from the Standard Model predictions, in b to s transitions. These anomalies can be explained through New Physics contributions or alternatively through underestimated hadronic effects. Both options will be presented in some detail, in addition to a direct statistical comparison of two global fits to the data based on the two different assumptions.

Date: April 4, 2017 @ 15:00 CET

Speaker: Claudia Frugiuele (Weizmann Institute)

Abstract: I will discuss the discovery prospects for light dark matter  focusing on fermilab based experiments. I will first describe the signal and then I will explain how to deal with the large neutrino background.

Please join the meeting by clicking this link: http://reunion.uv.es/webinar040417/

In order to avoid audio issues, we encourage the use of headphones and microphones, particularly when asking questions.

Note: Some audio problems have been detected using Ubuntu+Firefox or Windows+Chrome. Please, avoid these combinations of operating system and browser when connecting.

Speaker:  Orsten Bringmann (University of Oslo)

Abstract: Self-interacting dark matter has been the subject of increasing interest in recent years, motivated partially by the reported small-scale discrepancies between astrophysical observations
and the cosmological concordance model. In this context, an attractive way to achieve both strong, velocity-dependent self-interactions and thermal production is to couple dark matter to light new particles. I will discuss model-building avenues and the resulting phenomenology, with a particular focus on recently derived strong constraints on such models from the Cosmic Microwave Background and other indirect detection probes.

Speaker:  Dr. Asher Berlin (SLAC)

Abstract: Dark matter with mass below an electronvolt is a well-motivated scenario in theories beyond the Standard Model. In this talk, I will explore the possibility that a fraction of dark matter is composed of an ultra-light scalar particle that couples very feebly to active and or sterile neutrinos. If sufficiently light, this scalar behaves  as an oscillating coherent field, potentially leading to striking features in neutrino cosmology and terrestrial experiments.

Time and date: Tuesday June 12th 3pm (CET)

Speaker: Pierre Sikivie (Florida)

Title: "Axion physics and the 21 cm signal”

video:

Time and date: Tuesday April 24th 15:00 (CET)​

Speaker: J. B. Muñoz (Harvard U)

Abstract: The nature of the dark matter is still a mystery, although current and upcoming 21-cm measurements during the cosmic dawn can provide a new arena on the search for the cosmological dark matter.

​This era saw the formation of the first stars, which coupled the spin temperature of hydrogen to its kinetic temperature---​producing 21-cm absorption in the CMB. The strength of this absorption acts as a thermostat, showing us if the baryons have been cooled down or heated up by different processes.

I will show the discovery space for new dark-sector interactions, focusing on the case of "minicharged" dark-matter, which can explain the anomalous 21-cm depth observed by the EDGES collaboration.

Time and date: Tuesday April 10th 15:00 (CET)

Speaker: M. Golterman (San Francisco State U & Autonoma U. Barcelona)

Abstract: Extensions of the Standard Model in which the Higgs particle is a composite state of a new strong interaction can be studied using lattice gauge theory techniques.  Its lightness in such theories has a natural explanation if it is a pseudo Nambu-Goldstone boson arising from flavor symmetry breaking in the new strong sector, or if it is a "dilatonic" meson associated with approximate scale symmetry.  This talk will consider both scenarios in the context of recent results on the lattice

SPECIAL LECTURE

Date and time: Tuesday March 20th 15:00 (CET)

Speaker: Marina Rodriguez Baras (UAM)

Abstract: As nowadays there are no laws forbidding the access of women to education and research in most countries, there may be a general perception of having achieved gender equality in science. This is far from true: women keep being underrepresented in every stage of the scientific career, and studies and statistics show the existence of general and specific gender bias within our field. In this webinar we will go through all the stages of the scientific career to analyse this situation of gender inequality and its causes, as the pervasive gender stereotypes associated to science and technology in our societies or the work-life balance problems that are still mostly assumed by women. We will also consider which measures should be taken to close the gender gap in science, in order to reach real equal opportunity in research.

Date and Time: Tuesday March 6th @ 15:00 (CET)

Speaker: Matthew P. Mccullough (CERN)

Title:  “Microscopic Origins of the Weak Scale and the Power Spectrum of the LHC"

Abstract:  I will discuss the weak scale hierarchy problem from a known, but less mainstream, direction and I will argue that the hints we have observed for high energy physics may in fact be a smokescreen, with the new physics responsible for these hints lying much closer to accessible energies.  In the main talk I will discuss recent progress in model building, focussing on clockwork models along with their associated linear dilaton continuum limit, including connections to stringy scenarios.  The second half of the talk will focus on LHC phenomenology for this class of models, including a new search strategy to look for evidence of new physics in Fourier space.

Date and time: Tuesday February 20th @ 15:00 (CET)

Speaker: Gabriel MartÌnez-Pinedo (GSI and TU Darmstadt)

Abstract: On August 17th 2017, the LIGO/VIRGO collaborations detected the gravitational signal GW170817 originating from a merger of two neutron stars. Shortly after an electromagnetic signal with an intrinsic brightness corresponding to thousand novas was detected by several telescopes worldwide lasting around a week. This kilonova signal has been predicted by theory long before and originates from the radioactive decay of freshly synthesized radioactive heavy nuclei produced by the r process. Hence, it answers one of the long lasting questions in nuclear astrophysics related to the astrophysical site of the r process. In this talk, I will summarize our current understanding of the r process, the answers provided by the recent observations and the remaining open questions.

Date and time: Tuesday February 13th 2018 @ 15:00 (CET)

Speaker: K. Zurek (Berkeley and CERN)

Abstract: Searches for massive dark matter have largely focused on a mass window near the weak scale, the so-called “WIMP window".  This window is, however, becoming increasingly closed by both the LHC and the unprecedented sensitivity of direct detection experiments.  At the same time, theoretical work in recent years has shown lighter dark matter candidates in a hidden sector are theoretically well-motivated, natural and arise generically in many theories beyond the standard model.  New ideas are needed to search for dark matter with mass below a GeV and as light as the warm dark matter limit of a keV. We propose new ideas to search for such light dark matter with superconductors, semi-conductors, graphene, Dirac materials, and superfluid helium.  We show that these same experiments, through inelastic processes, may also be sensitive to dark matter with masses in the meV to keV mass window, broadening the mass reach to light dark matter by many orders of magnitude.

Date and time: Tuesday February 6th @ 15:00 (CET)

Speaker: I. Tamborra (Niels Bohr)

Abstract: The merging of two neutron stars or a neutron star and a black hole are dense in neutrinos.  We will review the role of neutrinos and their flavor conversions in the synthesis of the heavy elements above the merger torus. The chances of detecting high-energy neutrinos produced in the merger aftermath will be also discussed.

Date and time: January 9th, 2018 at 15:00 (CET)
Speaker: S. Davidson (CNRS)
Abstract: The QCD Axion is a Beyond-the-standard-model Curiosity. Originally introduced to solve the strong CP problem, it is effectively described by  a one-particle, one-parameter new physics model,  and, despite having a mass comparable to the neutrino's, it is a Cold Dark Matter candidate. In the scenario where the axion is born after inflation, I will review the growth of Large Scale Structure in the presence of axion CDM, and speculate about  axion configurations in our galaxy today.

Time and date:  Tuesday December 10th   @15:00 (CET)

Speaker: Seyda Ipek (Department of Physics and Astronomy, University of California Irvine)

Abstract:  Generally we do not think about QCD when we try to explain the matter--antimatter asymmetry of the universe. I will describe a small modification to the SM which drastically changes the QCD confinement in the early universe. In this model the strong coupling constant is a dynamical quantity which depends on the vacuum expectation value of a new scalar field. In this history of our Universe the QCD confines through a first-order phase transition at a temperature of T ~ O(100 GeV), when sphalerons are still active. Large CP violation can also exist in the strong sector — which is then cancelled by the QCD axion. I will explain this baryogenesis scenario and the rich set of phase transitions in the model.

Time and date:  Tuesday November 26th @15:00 (CET)

Speaker: Leonardo Mastrototaro (Interuniversity department of physics “Michelangelo Merlin”)

Abstract:  Heavy sterile neutrinos with masses in the MeV-GeV are predicted in extension of the Standard Model, like neutrino Minimal Standard Model (νMSM). In this talk, we consider the possibility that heavy sterile neutrinos with masses O(100) MeV are produced in the core of a collapsing supernova (SN). We will constrain the mass-mixing parameter space of the heavy sterile neutrino, from the energy loss argument from SN 1987A. Finally, we will characterize the observable active neutrino signal in large underground detectors, induced by decays of heavy sterile neutrinos in the SN envelope.

This talk is based on: Leonardo Mastrototaro, Alessandro Mirizzi, Pasquale Dario Serpico and Arman Esmaili, “Heavy sterile neutrino emission in core-collapse su- pernovae: Constraints and signatures” (2019), arXiV:1910.10249

Time and date:  Tuesday November 12th @15:00 (CET)

Speaker: Joerg Jaeckel (Institut für Theoretische Physik, Universität Heidelberg)

Abstract: In this talk we will have a look at dark matter made from very light bosons. After a brief review of the standard scenario of axion-like particles (ALPs) we will discuss some surpising aspects regarding the stability of ALP DM. Then we turn to non-minimal models. In particular we consider a scenario where the field space of the ALP is enlarged by a monodromy. In addition we have a look at the case where the light boson caries an approximately conserved charge.

Time and date:  May 28, 2019 at 15h00 CET

Speaker: Daniele Gaggero (Instituto de Física Teórica UAM/CSIC)

Abstract: The birth of gravitational wave astronomy has been a major recent breakthrough in physics. The recent discovery of gravitational wave signals from merger events of massive binary-black-hole (BBH) systems have prompted a renewed debate in the scientific community about the existence of primordial black holes of O(1-100) solar masses. These objects may have formed in the early Universe and could constitute a significant portion of the elusive dark matter that, according to standard cosmology, makes up the majority of the matter content in the universe.

I will review the most recent development of this field, with particular focus on the mass window of interest for the LIGO and Virgo gravitational observatories. I will discuss in detail the most updated computations of the expected merger rate of a hypothetical subdominant population of primordial black holes, taking into account the impact of the dark matter “dresses” that are expected to form around these objects.

I will also present the prospects of discovery with forthcoming radio facilities such as SKA and ngVLA, and the possible consequences of such discovery on the existence of other dark matter candidates

Time and date:  Tuesday, May 07, 2019 at 15h00 CET

Speaker: Derek B. Fox (Penn State University)

Abstract: The March 2018 report of two anomalous (Earth-emergent) e_cr ~ 0.6 EeV air showers by the ANITA collaboration has presented a severe puzzle of interpretation. Given existing limits on neutrino transient sources and the diffuse neutrino flux, these events are straightforwardly impossible under the Standard Model, due primarily to the challengesof propagating SM particles of these energies along the observed extended path lengths. I will review the nature of the ANITAexperiment and the properties of their anomalous events, and presentour arguments for the incompatibility of these observations with the Standard Model. I will also explore the possible existence of analog events among the highest-energy neutrinos of the IceCube neutrinoobservatory. Together, these observations encourage us to consider the chief alternative, that the ANITA Anomalous Events are mediated by arelatively long-lived Beyond Standard Model (BSM) particle. I will present our inferences as to the necessary properties of thisparticle, which appear consistent (at least in part) with those predicted for the "stau" slepton in some supersymmetric modelsof the fundamental interactions. LHC Run 2 data now under analysis may prove to be highly relevant in this context.

Time and date:  April 23, 2019 at 15h00 CET

Speaker: Thomas Mannel and Oscar Catà (Siegen University)

Abstract: Hints of violation of lepton flavor universality in semileptonic B decays have prompted a renewed interest in leptoquarks at the low TeV scale. Among the different scenarios suggested, some happen to violate also lepton number, yet not much attention has been paid to the expected size of the associated lepton number violating processes. In this webinar we will consider this issue, starting from a short introduction into the status of  the B anomalies. We write down a model in terms of two leptoquarks which has a softly broken lepton number and discuss its predictions for neutrino masses and lepton-number violating B decays.

Time and date:  April 9th at 15h00 CET

Speaker: Isabel M. Oldengott (IFIC UV-CSIC)

Abstract: The by far strongest bound on the sum of the neutrino masses today comes from cosmological observations. Future surveys promise to even tighten this bound significantly and will be realized within the next decade. It is therefore crucial to be aware of parameter degeneracies and the main assumptions hiding behind the cosmological mass bound. We study the impact of non-standard momentum distributions of cosmic neutrinos on the anisotropy spectrum of the cosmic microwave background and the matter power spectrum of the large scale structure.

We show that the neutrino distribution has almost no unique observable imprint, as it is almost entirely degenerate with the the neutrino mass and the effective number of neutrino flavours. Performing a Markov chain Monte Carlo analysis with current cosmological data, we demonstrate that the neutrino mass bound therefore heavily depends on the assumed momentum distribution of relic neutrinos.

Time and date:  Tuesday March 26th at 15h00 CET

Speaker: Francis-Yan Cyr-Racine (University of Harvard)

Abstract: New physics in the neutrino sector might be necessary to address anomalies between different neutrino oscillation experiments. Intriguingly, it also offers a possible solution to the discrepant cosmological measurements of H_0. We show here that delaying the onset of neutrino free-streaming until close to the epoch of matter-radiation equality can naturally accommodate a larger value for the Hubble constant, while not degrading the fit to the cosmic microwave background (CMB) damping tail.

We achieve this by introducing neutrino self-interactions in the presence of a non-vanishing sum of neutrino masses. This "strongly interacting" neutrino cosmology prefers a 3+1 neutrino scenario, which has interesting implications for particle model-building and neutrino oscillation anomalies. Due to their impact on the evolution of the gravitational potential at early times, self-interacting neutrinos and their subsequent decoupling leave a tell-tale structure on the matter power spectrum. Our analysis shows that it is possible to find radically different cosmological models that nonetheless provide excellent fits to the data, hence providing an impetus to thoroughly explore alternate cosmological scenarios.

Time and date:  Tuesday March 12th at 15:00 CET

Speaker: Tien-Tien Yu (University of Oregon)

Abstract: The sub-GeV dark matter mass range has received increased interest in the last several years, owing to the lack of any unambiguous signal of the canonical WIMP in the GeV-TeV mass range. The sub-GeV mass range is relatively unexplored due to the difficulty of detecting such light dark matter with traditional techniques. However, there have been recent experimental developments that finally make sub-GeV direct detection viable.

I will discuss some of the theoretical principles and strategies to explore sub-GeV dark matter candidates, as well as some current and proposed experimental techniques. I will focus predominantly on semiconductor targets, such as the new SENSEI experiment which utilizes silicon CCDs, and demonstrate the potential for exploring the eV-GeV dark matter mass range in the near future.

Time and date:  Tuesday February 12th, 2019

Speaker: Carlos Argüelles Delgado (Massachusetts Institute of Technology)

Abstract: Recently it has been suggested that the MiniBooNE excess can be explain by introducing a dark sector that which comprises of a dark neutrino and photon. These types of models are naturally embedded in neutrino mass generation scenarios. In this talk, we use neutrino scattering data from Minerva and CHARM-II to probe this class of models. We argue that by using sideband measurements of neutrino-electron scattering, we can significantly explore the parameter space motivated by the MiniBooNE results. Our new constraints show that a simultaneous explanation of the angular and energy distributions of the excess is in tension with neutrino-electron scattering data. Finally, we discuss how these types of measurements can play a role in further constraining the parameter space of these models.

Time and date: Tuesday, July 7th, 2020 @15:00 (CET)

Speaker: Juri Smirnov (Ohio State U.)

Title: "New Directions for Thermal Dark Matter"

Abstract: Thermal production mechanisms are a highly predictive framework in the dark matter model space. Charting possible realizations is important, as it leads to insights that guide experimental efforts to fully test particle dark matter. I will discuss bound-state formation effects that can affect the thermal relic abundance and lead to new dark matter scenarios and signatures. I will also present a novel thermal dark matter production mechanism, that can lead to monoenergetic electron recoils in laboratory experiments, for example XENON1T.

Time and date: Tuesday, June 16th @15:00 (CET)

Speaker: Yasaman Farzan (IPM, Iran & ICTP, Italy)

Title: "Unravelling  richness of dark sector by FASER$\nu$"

Abstract: FASER$\nu$ is a newly proposed experiment which will take data in  run III of the LHC during 2021-2023. It will be located in front of the FASER detector, 480~m away from the ATLAS interaction point  in the forward direction. Its main goal is to detect neutrinos of all flavors produced at the interaction point with superb precision in reconstructing charged tracks. This capability makes FASER$\nu$ an ideal setup for uncovering the pattern and properties of a light dark sector. We demonstrate this capability for a well-motivated class of  models with a dark matter candidate of mass around a few GeV. Dark matter annihilates to a pair of intermediate neutral particles that subsequently decay into the standard model charged fermions. We show how FASER$\nu$ can shed light on the structure of the dark sector by unravelling the decay chain within such models.

Slides: files/yasaman_slides.pdf

Time and date:  Tuesday April 21  @15:00 (CET)

Speaker:  Bradley Kavanagh (IFCA, Santander)

Title: "Detecting (Axion?) Dark Matter around Black Holes with Gravitational Waves"

Abstract: The observation of Gravitational Waves (GWs) has opened up a whole new avenue for constraining and detecting particle Dark Matter (DM). One of the most promising systems to study is the Intermediate Mass Ratio Inspiral (IMRI): a stellar-mass compact object such as a neutron star inspiraling towards an intermediate mass black hole, thousands of times more massive than the Sun. Sub-hertz GWs emitted during the inspiral should be detectable by future space-based observatories such as LISA. But the presence of DM in the system can have subtle dynamical effects on the inspiral, altering the waveform and hopefully allowing us to map out the DM distribution. In addition, multimessenger signals can arise when the DM is in the form of QCD axions, in which case the strong magnetic fields around the neutron star allow the conversion of axions to radio photons. Joint observations in GWs and radio would thus provide not only a detection of Dark Matter, but also a striking confirmation of its particle nature.

Time and date: Tuesday May 5th  @15:00 (CET)

Speaker:  Ryan Plestid (Kentucky U. & Fermilab)

Title: "Millicharged particles in neutrino detectors"

Abstract:  Millicharged particles (mCPs) represent one of the most minimal extensions of the Standard Model, and, until recently, were surprisingly poorly constrained for masses greater than roughly ~100 MeV. Recent proposals to discover mCPs have focussed on intense proton beams which result in meson cascades that can provide extremely large fluxes of mCPs; this "beam" of mCPs can, in turn, be detected at downstream detectors.
In this talk I will discuss how cosmic rays can act as a proton beam in their own right with the upper atmosphere serving as a fixed (and very thick) target. I will explain how, by combining well understood meson production cross sections, one can calculate the flux of mCPs from primary pp collisions. We find competitive constraints with accelerator based experiments, and find that our results can limit a recently proposed strongly-interacting dark matter "window".

Time and date: Tuesday May 19th  @15:00 (CET)

Speaker: Gilad Perez (Weizmann Institute of Science)

Title: "Searching for dark sectors with Kaon factories"

Abstract: The two kaon factories, KOTO and NA62, are at the cutting edge of the intensity frontier, with an unprecedented numbers of long lived and charged Kaons, ~ 10^{13}, being measured and analyzed. These experiments have currently a unique opportunity to search for dark sectors. We demonstrate, both via studying the experimental property and by constructing new physics (NP) models, that the searches done at KOTO and NA62 are complementary, both probing uncharted territories. We also mention that the model may be compatible with the preliminary analysis of the KOTO-data that shows a hint for NP.

Slides: Clik here

Time and date:  Tuesday March 24 @15:00 (CET)

Speaker:  James Cline (McGill University)

Abstract: I present a minimal model that attempts to address the main missing ingredients of the standard model: inflation, baryogenesis, dark matter, and the origin of neutrino masses.  We introduce a complex inflaton that decays into three generations of GeV-scale heavy neutral leptons, creating a lepton asymmetry during inflation.  One HNL is stable and provides (partially) asymmetric dark matter.  A light scalar singlet is needed to suppress its symmetric relic density.  Neutrino masses are generated by the usual seesaw mechanism, with heavy right-handed neutrinos above the inflation scale, and an MFV-like ansatz that relates neutrino masses to the HNL couplings, that are then linked to the light neutrino properties with only one adjustable parameter.  The stability of dark matter implies the lightest neutrino is massless.  The model is highly testable, and could explain excess events recently seen by KOTO.

Time and date:  Tuesday March 10th @15:00 (CET)

Speaker: Asimina Arvanitaki (Perimeter Institute for Theoretical Physics)

Abstract: While there is undisputed evidence for Dark Matter, its nature and properties remain one of the biggest questions of our time. What is Dark Matter(DM)? How is it produced? Does it have interactions other than gravitational? In this talk, I will describe how a large class of bosonic particles can account for the DM of the Cosmos. These particles can be much lighter than those of the Standard Model with Compton wavelengths that are bigger than the size of our solar system or smaller than a millimeter. In the presence of attractive self-interactions, there is a parametric resonance effect in the early universe that can cause growth of structure at small scales, an effect so dramatic that can cause structures to collapse well before matter-radiation equality. The signatures of this effect span several experiments and orders of magntude in parameter space. When the DM boson is heavy, the dense DM halos can alter the optimal search strategies in direct detection experiments. When the DM boson is light, these halos may leave their imprint in searches for dark matter substructure, primordial gravitational waves and alter the star formation history of the universe.

Time and date:  Tuesday February 25th @15:00 (CET)

Speaker:  Xiao- Ping Wang (HEP Argonne National Lab)

Abstract:  Long-lived particle is well motivated for the new physics search both for collider phenomenology and dark sector. We make use of new variables related to position to search for long-lived, basing on current CMS detector and the Phase-2 Upgrade of the CMS endcap calorimeter which is a high granularity silicon-based calorimeter (HGCAL). We study the long-lived particle signal induced by long-lived sterile neutrino and long-lived Higgs portal particle. The position related variables have been developed to suppress QCD and fake track backgrounds. The final results depends on trigger performance and are generally promising.

Time and date:  Tuesday February 11th @15:00 (CET)

Speaker: Jessica M. Turner (Fermilab)

Abstract:  In this talk I will discuss neutrino masses in general and demonstrate that non-zero neutrino masses can be generated from gravitational interactions. In this work we  solve the Schwinger-Dyson equations to find a non-trivial vacuum thereby determining the scale of the neutrino condensate and the number of new particle degrees of freedom required for gravitationally induced dynamical chiral symmetry breaking. We show for minimal beyond the Standard Model particle content, the scale of the condensation occurs close to the Planck scale.

Time and date:  Tuesday January 28th @15:00 (CET)

Speaker: Samuel J. Witte (Instituto de Física Corpuscular, UV/CSIC)

Abstract:  I will present recent work investigating the extent to which the CMB can serve as an indirect probe of neutrino mass models that contain a light neutrino-philic goldstone boson (or bosons). As a specific example I will focus the case where the type-I seesaw mechanism is realized from the spontaneous breaking of a global B-L symmetry, the pseudo goldstone boson here being identified as the majoron. I will show that current observations by Planck allow one to constrain symmetry breaking scales as high as ~ 1 TeV for majoron masses near the ~ eV scale. I will then discuss the current status of the so-called Hubble tension, and show that the present of a light majoron can help ameliorate this outstanding discrepancy.

Time and date:  Tuesday January 14th @15:00 (CET)

Speaker: Joachim Kopp (CERN & Mainz Institute for Theoretical Physics & PRISMA Cluster of Excellence)

Abstract:  We discuss the critical role that first order phase transitions in the early Universe may play in the production of dark matter.  We describe a mechanism dubbed "Filtered Dark Matter", where it is assumed that dark matter particles acquire mass during the phase transition, making it energetically unfavourable for them to enter the expanding bubbles of the massive phase. Instead, most of them are reflected off the advancing bubble walls and quickly annihilate away in the massless phase. Only the dark matter particles which have entered the bubbles survive to constitute the observed dark matter today.  Towards the end of the talk, we will also briefly mention other ways in which phase transitions can be crucial in determining the dark matter abundance, and we discuss how such scenarios can be probed experimentally.

Speaker: Laura Paulina Šinkunaite

Abstract:  LIGO employs two 4-km long FabryProt arm cavities, which need to be aligned in order for an interferometer to be locked on a TEM00 mode. Once the cavity is locked, alignment signals can be derived from wave-front sensors which measure the TEM01 mode content. However, the alignment state is not always good enough for locking on TEM00. Even when this is the case, the alignment can be evaluated using a free swinging cavity, that shows flashes when higher-order modes become resonant. By moving test masses, small changes are made to the mirror orientation, and hence the TEM00 mode can be optimized iteratively. Currently, this is a manual procedure, and thus
it is very time-consuming. Therefore, this project is aimed to study another possible way to lock the cavity on the TEM00 mode. Misalignment information can also be extracted from the power of the higher-order modes transmitted through the cavity. This talk will present an algorithm for this alternative and faster way to derive the alignment state of the arm cavities.

Abstract:  The QCD axion is among the best motivated candidates for Dark Matter. In a scenario, where the Peccei Quinn symmetry is restored after inflation the axion field acquires random initial values in causally disconnected patches of our universe. When the axion potential develops around the QCD phase transition fluctuations in the axion field are transferred into order 1 differences in the density contrast on comoving scales of roughly 0.02 pc. Besides, the decay of cosmic strings and domain walls, which are present as remnant of the phase transition, might add further inhomogeneities to the axion density. The regions of high overdensity collapse already around matter radiation equality, forming so called axion miniclusters.
The existence of axion miniclusters is crucial to the outcome of axion dark matter direct detection experiments but also of possible indirect signatures. In order to accurately predict the properties of miniclusters detailed knowledge of the density contrast previous to gravitational collapse is crucial.
In this talk I explain the production of axions from misalignment, string and wall decay and the difficulties in modeling these processes numerically. I continue by showing recent results of our numerical simulations, which follow the evolution of the axion field around the time of the QCD phase transition and determine the resulting density contrast, for the first time including all three relevant production processes. Our simulations indicate that the inclusion of strings and domain walls puts fluctuation power in scales, which are smaller than the horizon at the time of the QCD phase transition and we expect a large hierarchy of masses extending down to those smaller
scales.

Speaker: Gonzalo Alonso

Abstract:  Axion-like particles that couple to QCD via a G∧G term can induce a dependence of the mass of the proton and the neutron on the value of the axion field. It has been argued that an axion that couples too strongly to QCD results in the
underproduction of 4He during Big Bang Nucleosynthesis (BBN), which sets bounds on the allowed mass and decay constant of the axion. However, this very same effect results in a temperature-dependent effective potential for the axion in the presence of a background density of baryons, as there was in the early universe. Studying this effective potential leads to a deviation in the cosmological evolution of the axion field that can affect the BBN bounds.

Speaker: Fiona Kirk

Abstract: The neutrino Minimal Standard Model (nuMSM) allows to simultaneously explain neutrino oscillations, the existence of dark matter and the baryon asymmetry of the Universe, simply by completing the SM with three right-handed neutrinos with Majorana masses below the electroweak scale.
These BSM-particles can be searched for applying current day technology and experimental techniques, the only complication being the weak interaction rates. One way of testing the nuMSM is to study processes whose branching ratios are considerably enlarged by contributions of right-handed neutrinos. The nuMSM predictions for the branching ratios of flavour-violating muon decays were already estimated in [1], both flavour-violating muon and flavour violating tauon decays were considered here. All examined branching ratios were found to be too small to be detectable in near future, this being in agreement with the results of [1]. However, the application of the Casas- Ibarra parametrisation allowed for new insights into the role of the CP-violation phases in flavour-violating processes.

Date and time: December 18 th, 2017 17:00 CET

Speaker: Rachel Houtz

Abstract: Given the lack of conventional SUSY signals in the LHC data, a more complicated story may be required to explain weak scale physics.
I will present a class of natural models which ensure the one-loop divergences in the Higgs mass are cancelled. The top partners are not
related by an internal symmetry of the Lagrangian, but instead the symmetry relation that ensures the cancellation arises at an infrared
fixed point. Such a cancellation mechanism can, a la Little Higgs models, push the scale of the new physics that completely solves the
hierarchy problem up to 5-10 TeV. When embedded in a supersymmetric model, the superpartner masses provide the cutoffs for the loops, and
the mechanism alleviates the stop mass dependence on the Higgs mass parameter. We examine the case of a gauge boson top partner and a new
scalar top partner neutral under QCD.

Date and time: December 4th, 2017 at 11:00 CET

Speaker: Josu Hernandez

Title: The Quest for the Origin of Neutrino Masses

Abstract: Despite the remarkable agreement between a wide range of SM predictions and their experimental measurements, the SM has to be extended in order to explain the overwhelming experimental evidence from the neutrino oscillation phenomena supporting the existence of neutrino masses and mixings, which are absent in the SM. A simple and natural extension to account for neutrino masses is to introduce right-handed neutrinos in the particle content of the SM. Since these extra right-handed neutrinos are singlets under the SM gauge group, a Majorana mass term for these fermions is therefore allowed in the Lagrangian. One possibility is that this Majorana scale is above the EW scale but in the 100 GeV-TeV range. Then, the masses of the left-handed neutrinos arise in a simple way after ESB through the Weinberg operator in a low scale SM-Seesaw. In this situation, the presence of the new degrees of freedom will induce deviations from unitarity in the leptonic mixing matrix that appears in the charged current interactions. Thus, processes mediated by the weak currents would be modified, and therefore precision measurements of electroweak and flavor observables become a powerful tool to probe for the existence of heavy Majorana neutrinos. Following this idea, a global fit to the most complete and updated stringent set of electroweak and flavour observables to constrain the mixing of the extra heavy right-handed neutrinos in a model independent way has been performed. On the other hand, at some level, the addition of right-handed neutrinos will also impact neutrino oscillation searches. Therefore, the expected sensitivities of new generation of neutrino oscillation experiments to probe for this New Physics will be discussed too.

Date and time:  November 20th, 2017 at 11 CET

Speaker: Arsenii Titov

Title: Leptonic CP Violation from Discrete Flavour Symmetries

Abstract: Driven by the measured values of the neutrino mixing parameters, we adopt symmetry approach to neutrino mixing, based on the assumption of existence of a non-Abelian discrete flavour symmetry. The most distinct feature of this approach is correlations between the neutrino mixing angles and CP-violating phases, which are referred to as neutrino mixing sum rules. We first consider all types of the residual symmetries of the charged lepton and neutrino mass matrices for which such correlations are expected and derive the corresponding sum rules for the cosine of the Dirac phase $\delta$. Using these sum rules, we obtain predictions for $\cos\delta$ in the cases of several discrete flavour symmetries. Next, we concentrate on a scenario in which the main contribution to neutrino mixing arises from the neutrino sector in the form of highly symmetric mixing patterns. We explore possible charged lepton corrections to these patterns required to reconstitute their compatibility with experimental data. In the context of the proposed DUNE and T2HK facilities, we study (i) the compatibility of these symmetric mixing patterns with present neutrino oscillation data, and (ii) the potential of these experiments to discriminate between various symmetric patterns. Based on: http://arxiv.org/abs/arXiv:1410.8056, http://arxiv.org/abs/arXiv:1504.00658, http://arxiv.org/abs/arXiv:1509.02502 and http://arxiv.org/abs/arXiv:1711.02107.

Date and time: May 17th at 10 CET

Speaker: Andrea Caputo

Abstract: Pani (2015) updated upon a nice way to constrain the dark matter density using binary pulsars. The idea is that during the motion of a binary pulsar around the Galactic center, the pulsar and its companion experience a wind of dark-matter particles that would lead to a change in the orbital period, that might be detectable given the astonishing precision timing of pulsars. However, Pani (2015) only considered a smooth background dark matter density, which results in  too weak constraints. We focus instead our analysis in the interesting and rich scenario of a dark disk (DD); in particular we look upon the model proposed by Fan et al (2013) for a Double-Disk Dark Matter(DDDM).  In this case, the enhancement in the signal is manifest, and it is due to different causes: higher dark matter density, lower velocity dispersion for dark matter particles and binary's co-rotation with DD.

Date and Time: April 26th at 10 CET

Speaker: Rupert Coy

Abstract: The clockwork mechanism is a novel method for generating a large separation of scales naturally through a pattern of symmetry breaking. I shall outline how the mechanism can arise from strongly-coupled theories at the TeV scale. This provides a nice way to connect (nearly) EW-scale physics with UV physics, such as axions, GUTs, and inflation. Using the composite axion as a specific example, I will describe some of the interesting phenomenology that emerges from this realisation of the clockwork mechanism.

Date and time: April 6, 2017 @ 10:00 CET

Speaker: Alvaro Hernandez Cabezudo

Abstract: Neutrino oscillations in context of the 3 flavour neutrino scenario has been a very satisfactory explanation for lots of neutrino appearance and disappearance observations, being also the first evidence for physics beyond the standard model. But there are some experimental observations, that disagree with this framework. These observations, LSND, reactor and gallium anomalies could be explain with an additional neutrino mass eigenstate with a confidence around 3?.Concerning the reactor anomaly, the neutrino flux of the power plants is not very well understood, so it is very important to be aware of that when doing combined analysis of the different reactor neutrino experiments. A combined analysis is crucial, since these experiments work in different regimes of baselines, being complementary and covering different ranges of mass and mixing of the new neutrino. In the near future, a lot of reactor neutrino experiments will come and it will be possible to determine if these anomalies are due to this hypothetical neutrino.

Video: http://reunion.uv.es/p5m1qebfce8/

Date and time:  March 22, 2017 @ 11:00 CET

Speaker: Elena Perdomo (SOTON)

Abstract: We study standard and non-standard neutrino signals in direct dark matter detection experiments. The next generation of dark matter detectors will be soon sensitive to solar neutrinos via coherent neutrino-nucleus scattering. In this work, we compare the nuclear recoil rates expected from neutrino scattering with weakly interacting massive particle (WIMP) signals and we show that the scattering of neutrinos is an irreducible background for direct dark matter searches. We explore the possibility that neutrino interactions are enhanced by new physics with light mediators. We emphasize that the neutrino floor can be raised in the case that new scalar and vector mediators exist. Finally, we show how on the one hand, direct dark matter searches can be useful to probe or set constraints in new physics beyond the Standard Model, but on the other hand, their signatures could also be confused with dark matter signals.

Video :http://reunion.uv.es/p818x8j11ei/
Slides:http://reunion.uv.es/p3s476cwp70/

Speaker: Chloe Ransom

Abstract: Many extensions of the Standard Model explain the dominance of matter over antimatter in our Universe by neutrinos being their own anti-particles. This would imply that a lepton number violating radioactive decay named neutrinoless double beta (0???) decay exists, whose detection requires the upmost suppression of background. The Gerda collaboration searches for 0??? decay of Ge76 by operating bare germanium detectors, enriched in Ge76, in liquid argon. The Gerda experiment has instrumented the liquid argon (LAr) around the detecotr array with photomultiplier tubes (PMTs) for the readout of scintillation light thereby providing an active LAr veto system for background events. The PMTs currently used are not sensitive to LAr scintillation light, and use wavelength shifting foil to shift the LAr scintillation light to their region of sensitivity. A new PMT with a magnesium fluoride (MgF2) window is transparent to the LAr scintillation light, and therefore does not require the wavelength shifting foil. Reduction of material is important for a zero-background experiment such as Gerda. I present a summary of measurements made so far with this PMT, including gain, dark current and afterpulses rate, at both room temperature and cooled with nitrogen. Future work will include long-term tests in LAr.

Speaker: Nuno Agostinho

Abstract: Nowadays, neutrinos are the most astonishing evidence of Physics Beyond the Standard Model. The well-known seesaw mechanism provides a simple and natural way to give small masses to the three Standard Model neutrinos. The smallness of neutrinos is generated at an energy many orders of magnitude above the TEV scale. An obvious question is whether the manifestation of particles that mediate neutrino interactions can be within the LHC reach.

One will focus on a very interesting possibility of generating neutrino masses through a simple seesaw type III model, with minimal flavour violation. Within this context, the mass of neutrinos can be generated by fermion triplets. The advantage of the seesaw type III is that via electroweak gauge interactions, the decays of the triplets can have cross-sections that could allow for their observation at the LHC.

Therefore, in principle, the triplets can be light enough to be produced at the LHC (in type-I seesaw, one adds heavy neutrino singlets that can be produced in association with charged leptons, however, the small mixing with the Standard Model particles leads to unsatisfactory production rates for the new fermions).

Furthermore, these types of models have characteristic signatures such as suppressed lepton violation decays of the triplet fermions and predictable lepton flavour composition of the states produced in their decays and,  during the presentation, some examples will be given.

Speaker: Julia Gehrlein

Abstract: Correlations between light neutrino observables are common predictions of a large class of models based on the (discrete) symmetry approach to lepton flavour. Neutrino mass sum rules connect the three (complex) light neutrino mass eigenvalues among each other and mixing sum rules relate the leptonic mixing angles and the Dirac phase. However, in nearly all cases known, the sum rules are not exact and receive corrections from various sources. We will discuss generic corrections to these sum rules which arise for example from higher dimensional operators or renormalisation group evolution and present the effect of the corrections on the predictions from sum rules found in the literature. While in most cases the predictions of mass sum rules are fairly stable running effects for the mixing sum rules have to be taken into account to realistically probe the predictions from the sum rules in concrete models.

Date and time:  December 17th at 11:00 AM CET

Speaker: Nuno Rosa Agostinho

Abstract: Presently, the negative results of the search for direct new physics effects indicate that new states are probably heavy, therefore, there might exist a mass gap between the SM states and the new ones. Thus, against this background, effective lagrangians raise as a most adequate tool for scientific advancement and we perform a comprehensive study of the Higgs couplings, gauge-boson couplings to fermions and triple gauge boson vertices. Our framework of effective theories includes the effects of the dimension-six operators contributing to these observables. We quantify the improvement on the determination of the 20 Wilson coefficients by the inclusion of the Run 2 results and we discuss the discrete (quasi)-degeneracies existing in the parameter space of operator coefficients relevant for the Higgs couplings to fermions and gauge bosons.

Date and time:  November 26th at 11:00 AM CET

Speaker: Julia Gehrlein

Abstract: We generalize the scalar triplet neutrino mass model, the type II seesaw. Requiring fine-tuning and arbitrarily small parameters to be absent leads to dynamical lepton number breaking at the electroweak scale and a rich LHC phenomenology. A smoking gun signature at the LHC that allows to distinguish our model from the usual type II seesaw scenario is identified. Besides, we discuss other interesting phenomenological aspects of the model such as the presence of a massless Goldstone boson and deviations of standard model Higgs couplings.

Date and time: November 12th at 10:30 AM CET

Abstract: Axions can be produced in the early universe at very low momenta by the misalignment mechanism and provide an excellent candidate for dark matter. However, the resulting axion population is expected to exhibit large inhomogeneities, if the Peccei Quinn symmetry is restored after inflation. Such fluctuation of $\mathcal(O)(1)$ collapse very early, around matter radiation equality, and form dense lumps of dark matter called axion miniclusters. The relevant mass scale for axion miniclusters is about $10^{-12} M_\astrosun$. Not only could the miniclusters dramatically modify direct detection constraints but also would they offer a new way of testing axion dark matter -- via their gravitational lensing signal. Cosmological defects, inevitablely present in cosmological scenarios which lead to minicluster formation, and a large separation of scales make the prediction of the density contrast challenging. The density contrast, however, determines the mass spectrum and fraction of dark matter defined in miniclusters.

Date and time:  October 22nd at 11:00 AM CET

Speaker: Simon J. D. King

Abstract: In the framework of the (B - L) Supersymmetric Standard  Model (BLSSM), we assess the ability of ground and space based  experiments to establish the nature of its prevalent Dark Matter (DM) candidate, the sneutrino, which could either be CP-even or -odd. Firstly, by benchmarking this theory construct against the results obtained by the Planck spacecraft, we extract the portions of the BLSSM parameter space compliant with relic density data. Secondly, we show that, based on current sensitivities of the Fermi Large Area  Telescope (FermiLAT) and their future projections, the study of high-energy ?-ray spectra will eventually enable us to extract evidence of this DM candidate through its annihilations into W+W? pairs (in turn emitting photons), in the form of both an integrated flux and a differential energy spectrum which cannot be reconciled  with the assumption of DM being fermionic (like, e.g., a neutralino),  although it should not be possible to distinguish between the scalar and pseudoscalar hypotheses. Thirdly, we show that, while underground direct detection experiments will have little scope in testing  sneutrino DM, the Large Hadron Collider (LHC) may be able to do so in a variety of multi-lepton signatures, with and without accompanying  jets (plus missing transverse energy), following data collection during Run 2 and 3.

Date and time: October 8th at 11:00 AM CET

Speaker: Sergio González

Abstract: The theory of Unimodular Gravity(UG) has been proposed as apossible solution of the cosmological constant problem yielding the same classical predictions than General Relativity (GR). In this talk I will construct the quantum formulation of the theory and show that the cosmological constant is still protected. Furthermore, some quantum effects in the presence of matter are also analyzed and compared with the ones from GR, showing that, so far, there is no way to distinguish between both theories.

Date and time: May 4th, 2018 @ 17:00 CET

Speaker: Rachel Houtz (UAM)

Abstract: In this talk I present a model with an enlarged color sector which solves the strong CP problem via new massless fermions. QCD color is unified with another non-Abelian group with a large confinement scale. The spontaneous breaking of the unified color group provides a source of naturally large axion mass due to small size instantons, and as a result no very light axions are present in the low-energy spectrum. The axion scale may be not far from the TeV region which translates to observable signals at colliders. This model naturally enlarges the parameter space for axions which solve the strong CP problem well beyond that of invisible axion models.

Date and time: April 16th at 11:00 CET

Abstract: The baryon asymmetry of the Universe is one of the open problems of the SM of particle physics. One possible explanation for the generation of this asymmetry is leptogenesis, which arises naturally when trying to explain neutrino masses. After explaining the main features of vanilla leptogenesis, we will introduce the Minimal Lepton Flavour Violation hypothesis and study its consequences within the context of leptogenesis. We will see that with this setup we can find a relation between successful leptogenesis and neutrinoless double beta decay, a low-energy observable, opening the possibility to test this scenario.

Date and time: March 26, 2018 at 11:00 CET

Speaker: Hector Ramirez (UVEG)

Abstract: Scalar-tensor theories of gravity are the most general extensions of General Relativity, leading to second-order equations of motion. Several applications have been developed for early- and late-time Cosmology. In the context of inflation, they cover canonical inflation as well as several noncanonical models proposed in the literature. While solving the evolution equations of the perturbations in such a framework is in general a difficult task and the slow-roll approach is not always valid. I will show how to compute the inflationary observables in a simple yet very accurate way using the Generalized Slow-Roll approach, by employing a new model for G-inflation as an example.

Date and time: Monday March 12th at 16:00 CET

Speaker: Edoardo Vitagliano

Title: Filling the gap in GUNS: the solar neutrino flux at keV energies

Abstract: In the last few decades we have entered a new era in neutrino observations, from cosmic neutrino background detection proposals to high energy neutrinos astronomy. As theorists, we have to provide the expected flux at different energies. In this talk, I will discuss about a previous overlooked contribution to the "grand unified neutrino spectrum" (GUNS) at Earth: the Solar neutrino thermal flux at keV energies. Besides being a signal, such a flux would also be the background for a futuristic keV sterile neutrino direct detection experiment. I will review the processes contributing to this spectrum, with particular emphasis on thermal effects due to the presence of a plasma.

Date and time: February 26th, 2018 at 11:00 CET

Speaker: Olcyr Sumensari

Abstract: Even though the LHC searches so far did not unveil the new physics particles, the B-physics experiments at LHCb, BaBar and Belle hint towards deviations from Lepton Flavor Universality in both the tree-level and loop-induced B meson semileptonic decays. I will briefly review the models that can address these puzzles, propose one new model and discuss the main predictions that can be tested at LHCb and/or Belle-II. Particular emphasis will be given to Lepton Flavor Violation in B meson decays, which offer a very clean alternative to test the proposed New Physics scenarios.

Date and time: February 12th, 2018 at 16:00 CET

Speaker: Samuel Witte

Title: A Unified Halo-Independent Formalism for Direct Detection Experiments.

Abstract: In this talk I will present a new formalism that quite generically allows for the comparison of direct dark matter detection data in a halo-independent manner. This formalism, based on theorems from convex geometry, effectively eliminates all caveats that had limited the applicability of previously developed halo-independent methods; for example, halo-independent comparisons can now be made between putative measurements of the annual modulation and upper limits on the scattering rate in a statistically unambiguous way.

Date and time: January 15t, 2018 16:30 CET

Speaker: Xabier Marcano

Abstract: Flavor physics is fundamental for testing the standard model of particle physics and could be the key for discovering new physics. Nowadays, this kind of processes, observed in neutrino oscillations, give us the clearest evidence of the fact that the Standard Model of fundamental interactions needs to be modified. Some of the most popular theories that try to asses this issue postulate the existence of new heavy right-handed neutrinos, with masses in the energy range that the LHC experiment is currently exploring. We study the connection between the possible existence of these neutrinos and lepton flavor physics. We consider the inverse seesaw model as a particular realization of a low scale seesaw model and analyze its lepton flavor violating phenomenology, in particular the Higgs and Z boson decays to two leptons of different flavor. Moreover, we also explore the possibility of directly producing these new heavy neutrinos at the LHC.

Date and time: May 27th at 11:00 AM CET

Speaker:  Arsenii Titov

Abstract: We explore the possibility that dark matter interactions with Standard Model particles are dominated by interactions with neutrinos.

We examine whether it is possible to construct such a scenario in a gauge-invariant manner. We first study the coupling of dark matter to the full lepton doublet and confirm that this generally leads to the dark matter phenomenology being dominated by interactions with charged leptons. We then explore two different implementations of the neutrino  portal in which neutrinos mix with a Standard Model singlet fermion  that interacts directly with dark matter through either a scalar or vector mediator. In these cases we find that the neutrino interactions  can dominate the dark matter phenomenology. Present neutrino detectors can probe dark matter annihilations into neutrinos and already set the strongest constraints on these realisations. Future experiments such as Hyper-Kamiokande, MEMPHYS, DUNE, or DARWIN could allow to probe dark matter annihilation cross section to neutrinos down to the value required to obtain the correct thermal relic abundance.

Date and time: May 6th, at 10:30 AM

Speaker:  Andrea Caputo

Abstract: Axion and Axion-like particles are fascinating dark matter candidates and a great effort has been devoted to their study, both  theoretically and experimentally. In this talk I will discuss two different astrophysical searches. The first one consists in looking with radio telescopes for the spontaneous decay of axion dark matter using different targets as Dwarf Galaxies, Clusters or the Galactic Center. The second one uses the parity violating axion interactions to exploit the extreme precision of pulsar timing measurements and look for oscillations in the polarization angle of the pulsar signal.

Date and time: April 9th at 11:30 AM

Speaker:  Chloe Ransom

Abstract: The observation of the hypothetical process of neutrinoless double beta decay (0nbb) would demonstrate both lepton-number violation and the Majorana nature of the neutrino. The GERDA experiment searches for 0nbb of Ge-76 at LNGS, operating 36 kg of enriched germanium diodes that act simultaneously as both source and detector. Neutrinoless double-beta decay would be detected in calorimeters such as GERDA as a sharp peak at the Q-value (2039 keV for 76Ge). Determining the energy of events via dedicated calibrations of the detectors is therefore of key concern, in addition to precisely determining the energy resolution. Here I will discuss the calibration procedure of GERDA, the analysis of the calibration data, the determination of systematic uncertainties, and how these quantities affect the neutrinolessdouble-beta analysis and limit.

Date and time: March 25th, 2019

Speaker: Álvaro Hernández Cabezudo

Abstract: In this seminar I will remind you the status of the short baseline anomalies and their interpretation in terms of sterile neutrino oscillations, focusing on the strong tension between the appearance and the disappearance data sets, which tell us that the MiniBooNE and LSND excesses can not be interpreted in terms of active-sterile neutrino oscillations. I will bridge this issue to alternative explanations for the MiniBooNE excess, which since last summer is much more significant than LSND excess. The MiniBooNE low energy excess can not be explain by simple scenarios and any new explanation will have to deal with many constraints. I will summarize which are the most important constraints and requirements that have to be satisfied for the new models to explain the excess, giving as example some of the most recent proposals.

Date and time: March 4, 2019

Speaker: Gonzalo Alonso

Abstract: We review the status of CP-odd pseudoscalar searches at colliders and other high-energy physics experiments, highlighting the similarities and differences between axions, axion-like particles(ALPs) and other more exotic species of the "axion family? Aiming to determine the phenomenologically relevant interactions, we take into account loop effects and distinguish the model-dependent and  -independent components of the couplings, with special focus on electroweak gauge bosons. The particular case of heavy axions is analysed in more detail, showing the potential of the LHC to probe ample new regions of parameter space. To this aim, a two-coupling-at-a-time approach is followed, showcasing the importance of not limiting the study to specific individual interactions.

Date and time: February 11, 2019

Speaker: Elena Perdomo

Abstract: I will give an introduction to modular symmetries and how these symmetries can be interpreted as a family symmetry. Afterwards, I will focus on an SU(5) model in 6d where the two extra dimensions are compactified on a T_2/Z_2 orbifold, with a twist angle of \omega= ei2pi/3. Such construction suggests an underlying modular A_4 symmetry, leading to an effective \mu-\tau reflection symmetry at low energies.

This implies maximal atmospheric mixing and maximal leptonic CP violation.

Date and time:  January 21st  2019

Speaker: Rupert Coy

Abstract: In the absence of direct evidence of new physics, any UV theory can be reduced to its specific set of low-energy effective operators. As a case study, I derive the EFT for the seesaw extension of the Standard Model, with sterile neutrinos of mass M > m_W. All  Wilson coefficients generated at 1-loop are systematically computed. Hence, it becomes straightforward to (i) identify the seesaw parameters compatible with the smallness of neutrino masses; (ii) compute precision lepton observables, which may be sensitive to scales as large as M ? 10^3 TeV; and (iii) establish sharp correlations among those observables. I find that the flavour-conserving Wilson coefficients set an upper bound on the flavour-violating ones. The low-energy limits on \mu -> e and \tau -> e,\mu transitions suppress flavour violation in Z and Higgs decays, as well as EDMs, far beyond the experimental reach.The precision measurements of G_F, m_W, and the invisible Z width set more stringent bounds than present and future limits on \tau -> e,\mu transitions. I will also present a spurion analysis to compare the seesaw with different models, thus assessing the discriminating potential of the effective approach.

The Invisibles19 School took place from June 3 to June 7, 2019 at the Laboratorio Subterráneo de Canfranc, in northern Spain.

Access the video lectures by the following topics:

The Invisibles18 School took place from Aug 28 to Sept 01, 2018 at Study Center Raitenhaslach in Burghausen, Germany.

Access the video lectures by the following topics:

The Invisibles16 School took place from Sep 05 to Sep 09, 2016 at SISSA in Trieste, Italy.

Access the video lectures by the following topics:

- Gravitational Waves (P. Pani)

• VIDEOS:

- Theoretical aspects of Dark Matter (S. Matsumoto)

• VIDEOS:

- Axions (J. Redondo) -

• VIDEOS:

-  Experimental searches for Dark Matter (E. Aprile)

- Theory of CP Violation (A. Cohen)

- CP Violation in the quark sector (M. Sozzi)

- CP Violation in the lepton sector (S. Petcov)

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