Journal Club

Seminar Room, Mondays at 14:00

Monday 25th of January, 2016

Low energy IceCube data and a possible Dark Matter related excess

In this Letter we focus our attention on the IceCube events in the energy range between 60 and 100 TeV, which show an order 2-sigma excess with respect to a power-law with spectral index 2. We analyze the possible origin of such an excess by comparing the distribution of the arrival directions of IceCube events with the angular distributions of simply distributed astrophysical galactic/extragalactic sources, as well as with the expected flux coming from DM interactions (decay and annihilation) for different DM profiles. The statistical analysis performed seems to disfavor the correlation with the galactic plane, whereas clearly rules out the DM annihilation scenario. The small statistics till now collected does not allow to scrutinize the cases of astrophysical isotropic distribution and DM decay scenarios. For this reason we perform a forecast analysis in order to stress the role of future Neutrino Telescopes.
Comments: 5 pages, 3 figures. References added
Subjects: High Energy Physics - Phenomenology (hep-ph); Cosmology and Nongalactic Astrophysics (astro-ph.CO); High Energy Astrophysical Phenomena (astro-ph.HE); High Energy Physics - Experiment (hep-ex)
Cite as: arXiv:1601.02934 [hep-ph]
  (or arXiv:1601.02934v2 [hep-ph] for this version)
Presented by A. Soto
 

A novel method to deal with off-shell particles in cascade decays

We propose a novel algorithm to compute the width of any generic n-body decay involving multiple off-shell particles having zero and non-zero spins. Starting from a toy example, we show the computations for three different processes that contain spin-0, 12, and 1 off-shell particles. We have checked that our results match with the existing results at the analytical level. This proposal can be automatized and should be useful to compute the phase space for long cascade decays, without any Monte Carlo sampling.
Comments: 9 pages, 4 figures, pdflatex
Subjects: High Energy Physics - Phenomenology (hep-ph)
Cite as: arXiv:1601.02375 [hep-ph]
  (or arXiv:1601.02375v1 [hep-ph] for this version)
presented by A Soto

A realistic model for Dark Matter interactions in the neutrino portal paradigm

We discuss a simple extension of the Standard Model (SM) that provides an explicit realization of the dark-matter (DM) neutrino-portal paradigm. The dark sector is composed of a scalar Φ and a Dirac fermion Ψ, with the latter assumed to be lighter than the former. These particles interact with the SM through the exchange of a set of heavy Dirac fermion mediators that are neutral under all local SM symmetries, and also under the dark-sector symmetry that stabilizes the Ψ against decay. We show that this model can accommodate all experimental and observational constraints provided the DM mass is below$\sim 35\, \gev$ or is in a resonant region of the Higgs or Z boson. We also show that if the dark scalar and dark fermion are almost degenerate in mass, heavier DM fermions are not excluded. We note that in this scenario DM annihilation in the cores of astrophysical objects and the galactic halo produces a monochromatic neutrino beam of energy $\mfe$, which provides a clear signature for this paradigm. Other experimental signatures are also discussed.
Comments: 21 pages, 8 figures
Subjects: High Energy Physics - Phenomenology (hep-ph)
Cite as: arXiv:1601.05051 [hep-ph]
  (or arXiv:1601.05051v1 [hep-ph] for this version)

Presented by J. I. Illana