arXiv subjects

Daruosh Haji Raissi

Publications and source records attributed to Daruosh Haji Raissi.

3 recordsLinked to original sources

arXiv2020

New Collider Searches for Axion-like Particles Coupling to Gluons

Axion-like particles (ALPs) are pseudo Nambu-Goldstone bosons associated with spontaneously broken global symmetries emerging in many extensions of the Standard Model. Assuming the most general effective Lagrangian up to dimension-5 operators for an ALP interacting with the SM fields, we investigate for the first time the sensitivity of the LHC13 to the ALP production in association with a di-jet. This study is focused on light ALPs which appear as invisible particles at the detector. Performing a realistic detector simulation and deploying a multivariate technique to best discriminate the signal from backgrounds, we set expected upper bounds on the ALP coupling to gluons. A comprehensive set of background processes is considered, and it is shown that this process provides significant sensitivity to the ALP-gluon coupling and the resulting bound is more stringent than those already obtained at the LHC. We also present prospects for the HE-LHC27 and FCC-hh100 and show that these future colliders are able to improve the limits from the LHC by roughly one order of magnitude.

hep-ph↗

arXiv2020

Signs of new physics in top quark pair production associated with a neutrino pair at the LHC

In this paper, we examine the interactions of the top quarks with the $Z$ boson using the top quark pair production associated with neutrino pair ($t\bar{t}ν_{l}\bar{ν_{l}}$) at the LHC. In particular, potential constraints on the anomalous electroweak top-quark interactions are determined by considering two opposite-sign charged leptons, missing energy, and two b-tagged jets in the final state. The analysis is performed for a High Luminosity scenario of the LHC with an integrated luminosity of 3 ab$^{-1}$ of proton-proton collisions at a center-of-mass energy of 14 TeV. The $95\%$ confidence intervals are computed on the anomalous couplings considering a realistic detector simulation of an upgraded CMS detector including an average of 200 proton-proton interactions per bunch crossing. We find that the $t\bar{t}ν_{l}\bar{ν_{l}}$ channel can provide stringent bounds on the relevant Wilson coefficients and has the potential to serve as an additional handle beside the $t\bar{t}Z(Z\rightarrow l^{+}l^{-})$ and other channels to search for new physics.

hep-ph↗

arXiv2019

Loop induced singlet scalar production through the vector like top quark at future lepton colliders

In this paper, we explore the signature of a simplified model which includes a new singlet scalar state and a vector like quark at future lepton colliders. In particular, we study the production of the new singlet scalar in association with a photon, which proceeds through loop level diagrams involving vector like top quark partner, at future $e^-e^+$ colliders with different center-of-mass energies from 500 GeV to 3 TeV. To show the sensitivity of the process, the exclusion limits on the parameter space of the model are presented considering the decay of the singlet scalar into a pair of Higgs boson, followed by the decay of Higgs bosons into $b\bar{b}$ pairs. The results are compared to those obtained from the LHC, electroweak precision data and other channels at lepton colliders and it is shown that a notable sensitivity to the parameter space of the simplified model could be achieved.

hep-ph↗