Journal Club

Seminar Room, Mondays at 14:00

Monday 7th of April, 2014


On the flavor composition of the high energy neutrino events in IceCube

The IceCube experiment has recently reported the observation of 28 high-energy (> 30 TeV) neutrino events, separated into 21 showers and 7 muon tracks, consistent with an extraterrestrial origin. In this letter we compute the compatibility of such an observation with possible combinations of neutrino flavors with relative proportion (alpha_e:alpha_mu:alpha_tau). Although the 7:21 track-to-shower ratio is naively favored for (1:1:1) at Earth, this is not true once the atmospheric muon and neutrino backgrounds are properly accounted for. We find that, for an astrophysical neutrino E^-2 energy spectrum, the standard (1:1:1) at Earth from hadronic sources is excluded at 90% CL. If this proportion does not change, only three more years of data would be needed to exclude (1:1:1) at Earth at 3sigma CL. The best-fit is obtained for (1:0:0) at Earth, which cannot be achieved from any flavor ratio at sources with averaged oscillations during propagation. If confirmed, this result would suggest either a misunderstanding of the background events in IceCube, or even more compellingly, some exotic physics which deviates from the standard scenario.
Comments: 5 pages, 2 figures
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE); High Energy Physics - Experiment (hep-ex); High Energy Physics - Phenomenology (hep-ph)
Report number: IFIC/14-22
Cite as: arXiv:1404.0017 [astro-ph.HE]
  (or arXiv:1404.0017v1 [astro-ph.HE] for this version)

Presented by Masip


What do precision Higgs measurements buy us?

We study the sensitivities of future precision Higgs measurements and electroweak observables in probing physics beyond the Standard Model. Using effective field theory--appropriate since precision measurements are indirect probes of new physics--we examine two well-motivated test cases. One is a tree-level example due to a singlet scalar field that enables the first-order electroweak phase transition for baryogenesis. The other is a one-loop example due to scalar top in the MSSM. We find both Higgs and electroweak measurements are sensitive probes of these cases.
Comments: 3 figures, 2 tables
Subjects: High Energy Physics - Phenomenology (hep-ph)
Report number: UCB-PTH-14/06, IPMU14-0082
Cite as: arXiv:1404.1058 [hep-ph]
  (or arXiv:1404.1058v1 [hep-ph] for this version)

Presented by Santiago