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Location
ZOOM
Speaker
Krijn de Vries, Vrije Universiteit Brussel, Belgium
Host
Schroeder
In this seminar, the radar echo technique to probe high-energy particle cascades is discussed. Starting with a historical overview of early efforts to probe cosmic-ray air showers, we shift to the detection of particle cascades in more dense media with a focus on in-ice cascades. The radar scattering process and expected signal features are introduced, after which we focus on recent and upcoming experimental efforts to detect particle cascades in dense media.
Event Types
Location
ZOOM
Speaker
John Krizmanic, UMBC/CRESST/NASA/GSFC
Host
Schroeder
Developed as a NASA Astrophysics probe-class mission, the Probe Of Extreme Multi-Messenger Astrophysics (POEMMA) is designed to identify the sources of ultra-high energy cosmic rays (UHECRs) and to observe cosmic neutrinos. POEMMA consists of two spacecraft, each with a large Schmidt telescope, flying in a loose formation at 525 km altitude. The two spacecraft are orientated such to co-view the optical air fluorescence and Cherenkov signals from UHECR- and neutrino-induced extensive air showers (EAS).
Event Types
Location
ZOOM
Speaker
Gia Dvali, LMU-MPI, Munich
Host
We discuss how the S-matrix formulation of quantum gravity eliminates de Sitter vacua, both stable or meta-stable. The S-matrix constraint is enforced by the phenomenon of anomalous quantum break-time. This also puts an upper bound on the duration of inflation and points to new potentially-observable quantum gravitational imprints. In this way, through its S-matrix formulation, quantum gravity/string theory nullifies an outstanding cosmological puzzle and excludes the cosmological constant from the energy budget of our Universe.
Event Types
Location
ZOOM
Speaker
John Richard Ellis, King's College, London
Host
Raut
The NANOGrav pulsar timing array has recently reported strong evidence for a stochastic signal that might be due to gravitational waves (GWs). I will discuss an interpretation based on GW emission by loops of cosmic strings that I proposed with Marek Lewicki, and the predictions it makes for observations with other GW detectors including LISA and atom interferometers. If time permits, I will also discuss how these detectors might be sensitive to other sources of GWs.
Event Types
Location
ZOOM
Speaker
Pasquale Di Bari, University of Southampton
Host
Raut
I will discuss some recent ideas on how a GW production could accompany the origin of neutrino masses in the early universe in models where this occurs via a first order phase transition. I will discuss a specific case where even dark matter genesis could be the result of the same phase transition. This primordial GW production will be probed by next GW interferometers. In this way the search for a primordial stochastic GW background might in the next years shed light on stages in the history of the early universe that have so far been precluded.
Event Types
Location
ZOOM
Speaker
Olivier Martineau-Huynh, Sorbonne Université, Université Paris Diderot, CNRS, Laboratoire de Physique Nucléaire et de Hautes Energies (LPNHE)
Host
Schroeder
The Giant Radio Array for Neutrino Detection (GRAND) is an ambitious project for a gigantic network of radio antennas covering a total area of 200’000km², the size of England. GRAND will primarily aim at detecting neutrinos -and other cosmic particles- of ultra-high energy.
Event Types
Location
ZOOM
Speaker
Stephanie Hickford, Karlsruhe Institute of Technology
Host
Schroeder

Measurement of the absolute scale of the neutrino mass contributes to our current
understanding of massive neutrinos in the Standard Model of particle physics, and has
relevance and implications for observational cosmology and astroparticle physics. The
K Arlsruhe TRItium Neutrino (KATRIN) collaboration aims to determine the neutrino
mass with a sensitivity of 0:2 eV (90% CL). This will be achieved with a high-precision
measurement of the endpoint region of the tritium -electron spectrum. A t is per-

Event Types
Location
ZOOM
Speaker
Julian Heeck, University of Virginia
Host
Raut
As the (pseudo-)Goldstone boson associated with lepton number the Majoron is intimately connected and coupled to Majorana neutrinos. At loop level it receives couplings to all other Standard Model particles, including flavor-changing lepton and quark couplings. The Majoron is a promising long-lived dark matter candidate in the weak-coupling regime with unique indirect-detection signatures via neutrino fluxes. For larger couplings rare flavor-changing decays are a prime hunting ground for these axion-like particles that could ultimately help us to understand the seesaw mechanism.
Event Types
Location
ZOOM
Speaker
Anish Ghoshal, INFN Rome Tor Vergata, Italy
Host
Raut

Attempts to solve naturalness by having the weak scale as the only breaking of classical scale invariance in 4-dimensional Quantum Field Theories satisfy Total Asymptotic Freedom (TAF): the theory holds up to infinite energy, where all coupling constants flow to zero and is devoid of any Landau poles. Specifically we will discuss a fundamental field theory of the QCD axion in the totally asymptotically free (TAF) scenario, and the dynamics of the Peccei-Quinn (PQ) phase transition there-in.

Event Types
Location
ZOOM
Speaker
Tianjun Li, Texas A&M University
Host
Raut
Gauge coupling unification in the Supersymmetric Standard Models strongly implies the Grand Unified Theories (GUTs). With the grand desert hypothesis, we show that the supersymmetric GUTs can be probed at the future proton-proton (pp) colliders and the Hyper-Kamiokande experiment. For the GUTs with the GUT scale M_{GUT} smaller than 10^{16} GeV, we can probe the dimension-six proton decay via heavy gauge boson exchange at the Hyper-Kamiokande experiment.
Event Types