A. Bhattacharya

Reconciling neutrino flux from heavy dark matter decay and recent events at IceCube

A bstractThe IceCube detector has recently reported the observation of 28 events at previously unexplored energies. While the statistics of the observed events are still low, these events hint at the existence of a neutrino flux over and above the atmospheric neutrino background. We investigate the possibility that a significant component of the additional neutrino flux originates due to the decay of a very heavy dark matter (VHDM) particle via several possible channels into standard model particles. We show that a combination of a power law astrophysical neutrino spectrum and the neutrino flux from the decay of a DM species of mass in the range 150 − 400 TeV improves the fit to the observed neutrino events than that obtained from a best-fit astrophysical flux alone. Assuming the existence of an astrophysical background described by the IC best-fit, we also show that, for the decay of even heavier DM particles (mDM ~ 1 PeV), the same observations impose significant constraints on the decay lifetimes. Allowing the astrophysical flux normalization to vary leads to modifications of these limits, however, there is still a range of dark matter mass and lifetime that is excluded by the IC results.

Perturbative charm production and the prompt atmospheric neutrino flux in light of RHIC and LHC

A bstractWe re-evaluate the prompt atmospheric neutrino flux, using the measured charm cross sections at RHIC and the Large Hadron Collider to constrain perturbative QCD parameters such as the factorization and renormalization scales, as well as modern parton distribution functions and recent estimates of the cosmic-ray spectra. We find that our result for the prompt neutrino flux is lower than previous perturbative QCD estimates and, consequently, alters the signal-to-background statistics of the recent IceCube measurements at high energies.

CONFIRMATION OF THE OGLE-2005-BLG-169 PLANET SIGNATURE AND ITS CHARACTERISTICS WITH LENS–SOURCE PROPER MOTION DETECTION

We present Keck NIRC2 high angular resolution adaptive optics observations of the microlensing event OGLE-2005-BLG-169Lb, taken 8.21 years after the discovery of this planetary system. For the first time for a microlensing planetary event, the source and the lens are completely resolved, providing a precise measurement of their heliocentric relative proper motion,

Confirmation of the Planetary Microlensing Signal and Star and Planet Mass Determinations for Event OGLE-2005-BLG-169

{mu }_{mathrm{rel},mathrm{helio}}=7.44pm 0.17

Chemical evolution of the Galactic bulge as traced by microlensed dwarf and subgiant stars : VI. Age and abundance structure of the stellar populations in the central sub-kpc of the Milky Way

mas yr−1. This confirms and refines the initial model presented in the discovery paper and rules out a range of solutions that were allowed by the microlensing light curve. This is also the first time that parameters derived from a microlensing planetary signal are confirmed, both with the Keck measurements, presented in this paper, and independent measurements obtained with the Hubble Space Telescope in

The direct detection of boosted dark matter at high energies and PeV events at IceCube

I,V

OGLE-2012-BLG-0563Lb: a Saturn-mass planet around an M dwarf with the mass constrained by Subaru AO imaging

and B bands, presented in a companion paper. Hence, this new measurement of

The Exoplanet Mass-Ratio Function from the MOA-II Survey: Discovery of a Break and Likely Peak at a Neptune Mass

{mu }_{mathrm{rel},mathrm{helio}}

Prompt atmospheric neutrino fluxes: perturbative QCD models and nuclear effects

, as well as the measured brightness of the lens in H band, enabled the mass and distance of the system to be updated: a Uranus-mass planet (

The first Neptune analog or super-earth with a Neptune-like orbit: MOA-2013-BLG-605LB

{m}_{{rm{p}}}=13.2pm 1.3{M}_{oplus }