• Ritesh K Singh

Articles written in Pramana – Journal of Physics

• Working group report: High energy and collider physics

This is a summary of the projects undertaken by the working group I on high energy and collider physics.

• Probing CP-violating Higgs contributions in $\gamma \gamma \rightarrow f\bar{f}$

We discuss the use of fermion polarization for studying neutral Higgs bosons at a photon collider. To this aim we construct polarization asymmetries which can isolate the contribution of a Higgs boson 𝜙 in $\gamma \gamma \rightarrow f\bar{f}$, $f = \tau/t$, from that of the QED continuum. This can help in getting information on the $\gamma \gamma \phi$ coupling in case 𝜙 is a CP eigenstate. We also construct CP-violating asymmetries which can probe CP mixing in case 𝜙 has indeterminate CP. Furthermore, we take the MSSM with CP violation as an example to demonstrate the potential of these asymmetries in a numerical analysis. We find that these asymmetries are sensitive to the presence of a Higgs boson as well as its CP properties over a wide range of MSSM parameters.

• Anomalous $V V H$ interactions at a linear collider

We examine, in a model independent way, the sensitivity of a linear collider to the couplings of a light Higgs boson to a pair of gauge bosons, including the possibility of CP violation. We construct several observables that probe the various possible anomalous couplings. For an intermediate mass Higgs, a collider operating at a center of mass energy of 500 GeV and with an integrated luminosity of 500 fb-1 is shown to be able to constrain the $ZZH$ vertex at the few per cent level, with even higher sensitivity for some of the couplings. However, lack of sufficient number of observables as well as contamination from the $ZZH$ vertex limits the precision to which anomalous part of the $W W H$ coupling can be probed.

• Lepton distribution in top decay: A probe of new physics and top-polarization

We investigate the possibilities of studying new physics in various processes of 𝑡-quark production using kinematical distributions of the secondary lepton coming from decay of 𝑡 quarks. We show that the angular distributions of the secondary lepton are insensitive to the anomalous $tbW$ vertex and hence are pure probes of new physics in a generic process of 𝑡-quark production. The effects of 𝑡 polarization on the distributions of the decay lepton are demonstrated for top-pair production process at a $\gamma \gamma$-collider mediated by a heavy Higgs boson.

• # Pramana – Journal of Physics

Volume 95, 2021
All articles
Continuous Article Publishing mode

• # Editorial Note on Continuous Article Publication

Posted on July 25, 2019