arXiv subjects

Roshan Mammen Abraham

Publications and source records attributed to Roshan Mammen Abraham.

22 records · Page 2Linked to original sources

arXiv2022

Directly Probing the Higgs-top Coupling at High Scales

We explore the sensitivity to new physics for the coupling of the Higgs boson ($h$) and top quark ($t$) at high energy scales with the process $pp\to t\bar{t}h$ at the high-luminosity LHC. This process probes the coupling in both the space-like and time-like domains at a high scale, complementary to the off-shell Higgs processes in the time-like domain. The effects from physics beyond the Standard Model are parametrized in terms of the effective field theory framework and a non-local Higgs-top form factor. Focusing on the boosted Higgs regime in association with jet substructure techniques, we show that the present search can directly probe the Higgs-top coupling to good precision, providing a strong sensitivity to the new physics scale.

hep-ph↗

arXiv2021

Discovering Dark Matter at the LHC through Its Nuclear Scattering in Far-Forward Emulsion and Liquid Argon Detectors

The LHC may produce light, weakly-interacting particles that decay to dark matter, creating an intense and highly collimated beam of dark matter particles in the far-forward direction. We investigate the prospects for detecting this dark matter in two far-forward detectors proposed for a future Forward Physics Facility: FASER$ν$2, a 10-tonne emulsion detector, and FLArE, a 10- to 100-tonne LArTPC. We focus here on nuclear scattering, including elastic scattering, resonant pion production, and deep inelastic scattering, and devise cuts that efficiently remove the neutrino-induced background. In the invisibly-decaying dark photon scenario, DM-nuclear scattering probes new parameter space for dark matter masses 5 MeV $\lesssim m_χ \lesssim$ 500 MeV. When combined with the DM-electron scattering studied previously, FASER$ν$2 and FLArE will be able to discover dark matter in a large swath of the cosmologically-favored parameter space with MeV $\lesssim m_χ \lesssim $ GeV.

hep-ph↗

arXiv2021

Neutral Current Neutrino Interactions at FASER$ν$

In detecting neutrinos from the Large Hadron Collider, FASER$ν$ will record the most energetic laboratory neutrinos ever studied. While charged current neutrino scattering events can be cleanly identified by an energetic lepton exiting the interaction vertex, neutral current interactions are more difficult to detect. We explore the potential of FASER$ν$ to observe neutrino neutral current scattering $νN \to νN$, demonstrating techniques to discriminate neutrino scattering events from neutral hadron backgrounds as well as to estimate the incoming neutrino energy given the deep inelastic scattering final state. We find that deep neural networks trained on kinematic observables allow for the measurement of the neutral current scattering cross section over neutrino energies from 100 GeV to several TeV. Such a measurement can be interpreted as a probe of neutrino non-standard interactions that is complementary to limits from other tests such as oscillations and coherent neutrino-nucleus scattering.

hep-ph↗

arXiv2020

Macro detection using fluorescence detectors

Macroscopic dark matter (aka macros) constitutes a broad class of alternatives to particulate dark matter. We calculate the luminosity produced by the passage of a single macro as a function of its physical cross section. A general detection scheme is developed for measuring the fluorescence caused by a passing macro in the atmosphere that is applicable to any ground based or space based Fluorescence Detecting (FD) telescopes. In particular, we employ this scheme to constrain the parameter space ($σ_{x} \mbox{ vs} \mbox{ M}_{x}$) of macros than can be probed by the Pierre Auger Observatory and by the Extreme Universe Space Observatory onboard the Japanese Experiment Module (JEM-EUSO). It is of particular significance that both detectors are sensitive to macros of nuclear density, since most candidates that have been explored (excepting primordial black holes) are expected to be of approximately nuclear density.

astro-ph.HE↗