BEGIN:VCALENDAR
VERSION:2.0
CALSCALE:GREGORIAN
PRODID:UW-Madison-Physics-Events
BEGIN:VEVENT
SEQUENCE:2
UID:UW-Physics-Event-7800
DTSTART:20220817T200000Z
DTEND:20220817T230000Z
DTSTAMP:20260414T113423Z
LAST-MODIFIED:20220803T142754Z
LOCATION:Chamberlin Hall 4274 
SUMMARY:New Physics with PeV Astrophysical Neutrino Beams\, Thesis Def
 ense\, Ibrahim Safa \, Physics PhD Graduate Student
DESCRIPTION:Astrophysical neutrinos allow us to access energies and ba
 selines that cannot be reached by human-made accelerators\, offering u
 nique probes of new physics phenomena. This thesis aims to address the
  challenges currently facing searches for Beyond Standard Model (BSM) 
 physics in the high-energy universe using astrophysical neutrinos\, pa
 rticularly in the contexts of flavor measurements and connections with
  dark matter. 
\nThe search for new physics with astrophysical neutrin
 os requires as a prerequisite understanding standard neutrino sources\
 , which remain ambiguous. We begin by performing a multi-wavelength se
 arch for astrophysical neutrino sources using nine years of IceCube da
 ta. We find hints of neutrino emission from radio-bright Active Galact
 ic Nuclei (AGN)\, further supporting recent claims that neutrino emiss
 ion occurs near the core of AGNs.
\nNext we turn our attention to BSM 
 searches. Accurate flavor measurements of the astrophysical flux provi
 de a smoking gun signature to BSM physics. This requires a precise mea
 surement of the tau neutrino fraction. However\, tau identification pr
 oved a major hurdle in the current generation of observatories. We con
 front the problem of astrophysical neutrino flavor measurements by fir
 st introducing Taurunner\, a simulation tool that accurately models th
 e propagation of tau neutrinos including previously neglected effects 
 such as tau lepton energy losses and depolarization in matter. We show
  that better modeling of tau neutrino propagation improves IceCube tra
 nsient point-source sensitivities by more than an order of magnitude a
 t EeV energies\, and diffuse flux sensitivities by a factor of two. Se
 cond\, we use this software to model IceCube counterparts to anomalous
  events reported by the ANITA experiment. After performing an analysis
  using IceCube data\, we show that all Standard Model explanations are
  ruled out.
\nLooking ahead to the future of flavor measurements\, we 
 also present a study that predicts the production of tau neutrinos via
  the propagation of electron and muon neutrinos in Earth\, finding an 
 irreducible but quantifiable background to next-generation tau neutrin
 o observatories.
\nFinally\, we attempt to address the field's shared 
 ignorance of the origin of neutrino and dark matter masses by explorin
 g potential connections between the two. Specifically\, we present an 
 analysis of dark matter annihilation and decay to neutrinos. 
\nWe obt
 ain limits from MeV to ZeV masses using more than a dozen neutrino exp
 eriments. Notably\, using recent data from the SuperKamiokande experim
 ent\, we place the first-ever limit on dark matter annihilation that r
 eaches the thermal relic abundance in the neutrino sector\, challengin
 g notions that studies with neutrinos cannot be sensitive enough to ma
 ke strong claims about the nature of dark matter.
\n
URL:https://www.physics.wisc.edu/events/?id=7800
END:VEVENT
END:VCALENDAR