Free Meson Seminars

Neutrino Mass and Dark Matter in light of recent AMS-02 results in light of recent AMS-02 results

by Prof. Dilip Ghosh (Indian Association for the Cultivation of Science, Kolkata)

Thursday, September 18, 2014 from to (Asia/Kolkata)
at AG69
Description
We study a simple extension of the Standard Model supplemented by an
electroweak triplet scalar field to accommodate small neutrino masses
by the type-II seesaw mechanism, while an additional singlet scalar
field can play the role of cold dark matter (DM) in our Universe.
Using the recently released high precision data on positron fraction
and flux from the AMS-02 experiment, we examine the DM interpretation
of the observed positron excess in our model for two kinematically
distinct scenarios with the DM and triplet scalar masses (a)
non-degenerate (mDM ≫ mΔ) and (b) quasi-degenerate (mDM
≃ mΔ). We find that a good fit to the AMS-02 data can be
obtained in both cases (a) and (b) with a normal hierarchy of neutrino
masses, while the inverted hierarchy case is somewhat disfavored.
Moreover, the absence of an excess anti-proton flux as suggested by
PAMELA data sets an indirect upper limit on the DM-nucleon
spin-independent elastic scattering cross section which is stronger
than the existing DM direct detection bound from LUX in the AMS-02
preferred DM mass range.