Journal Club

Seminar Room

Monday 7th of April, 2014

 

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

Olga Mena, Sergio Palomares-Ruiz, Aaron C. Vincent (Valencia U., IFIC)
(Submitted on 31 Mar 2014)
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?

Brian Henning, Xiaochuan Lu, Hitoshi Murayama
(Submitted on 3 Apr 2014)
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