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S. Rai Choudhury

Publications and source records attributed to S. Rai Choudhury.

28 records · Page 2Linked to original sources
arXiv2002

Lepton polarization asymmetry in radiative dileptonic B-meson decays in MSSM

In this paper we study the polarization asymmetries of the final state lepton in the radiative dileptonic decay of B meson (\bsllg) in the framework of Minimal Supersymmetric Standard Model (MSSM) and various other unified models within the framework of MSSM e.g. mSUGRA, SUGRA (where condition of universality of scalar masses is relaxed) etc. Lepton polarization, in addition of having a longitudinal component (\pl), can have two other components, \pt and \pn, lying in and perpendicular to the decay plane, which are proportional to \ml and hence are significant for final state being $μ^+ ~ μ^-$ or $τ^+ \~τ^-$. We analyse the dependence of these polarization asymmetries on the parameters of the various models.

hep-ph↗
arXiv2002

SUSY effects on the exclusive semi-leptonic decays $B \to πτ^+ τ^-$ and $B \to ρτ^+ τ^-$

In this paper we study the polarization asymmetries of the final state lepton in the radiative dileptonic decay of B meson (\bsllg) in the framework of Minimal Supersymmetric Standard Model (MSSM) and various other unified models within the framework of MSSM e.g. mSUGRA, SUGRA (where condition of universality of scalar masses is relaxed) etc. Lepton polarization, in addition of having a longitudinal component (\pl), can have two other components, \pt and \pn, lying in and perpendicular to the decay plane, which are proportional to \ml and hence are significant for final state being $μ^+ ~ μ^-$ or $τ^+ \~τ^-$. We analyse the dependence of these polarization asymmetries on the parameters of the various models.

hep-ph↗
arXiv2002

CP asymmetries in dileptonic decays of B-meson in MSSM

Scalar interactions (in effective Hamiltonian) can give significant variation of various experimental observables, as comparted to their respective Standard Model values, in dileptonic decays of B-meson. Also the quark level transition $b \to d \ell^- \ell^+$ can be useful to test CP violation. Here we will do comparative study of CP violation in two independent processes, which have the same quark level transition ($b \to d \ell^- \ell^+$), $B \to X_d \ell^- \ell^+$ (the inclusive decay mode) and the exclusive channel $B_d \to \ell^- \ell^+ γ$ (radiative dileptonic decay mode). We will mainly focus on the comparative study of scalar interactions on the CP asymmetries in these two different channels.

hep-ph↗
arXiv2002

Supersymmetric effects in B_s \to \ell^+ \ell^- γdecays

B-meson decays are very useful probes for testing the Standard Model and its various extensions. Leptonic decays of B have very clean signatures in this respect and hence can be very useful testing grounds. In this work we study the effects of MSSM (Minimal Supersymmetric Extension of Standard Model) on various kinematical distributions in the radiative dileptonic decay (\bsllg). We study the Forward Backward asymmetry (of the lepton pair), and the various polarization asymmetries of both final state leptons ($\ell^-$ and $\ell^+$). In radiative dileptonic decay of B-meson (\bsllg) the final state photon can also be polarized. So in this channel one can also study the polarization effects of the final state photon.

hep-ph↗
arXiv2002

Unitarity constraints on the stabilized Randall-Sundrum scenario

Recently proposed stabilization mechanism of the Randall-Sundrum metric gives rise to a scalar radion, which couples universally to matter with a weak interaction ($\simeq 1$ TeV) scale. Demanding that gauge boson scattering as described by the effective low enerrgy theory be unitary upto a given scale leads to significant constraints on the mass of such a radion.

hep-ph↗
arXiv2000

Longitudinal Polarization in $K_L \to μ^+ μ^-$ in MSSM with large $tanβ$

A complete experiment on decay $K_L \to l^+ l^-$ will not only consist of measurement of the decay rates but also lepton polarization etc. These additional observations will yield tests of CP invariance in these decays. In $K_L$ and $K_S$ decays, the e mode is slower than the $μ$ mode by roughly $(m_e/m_μ)^2$ \cite{sehgal1}. As well discussed in literature \cite{herczeg} the Standard Model contribution to the lepton polarization is of order $2 \times \sim 10^{-3}$. We show that in MSSM with large \tanbeta and light higgs masses ($\sim 2 M_W$), the longitudinal lepton polarization in $K_L \to μ^+ μ^-$ can be enhanced to a higher value, of about $10^{-2}$.

hep-ph↗
arXiv1999

τPolarization asymmetry in $B \to X_s τ^+ τ^-$ in SUSY models with large $tanβ$

Rare B decays provides an opportunity to probe for new physics beyond the standard model. the effective Hamiltonian for the decay $b \to s l^+ l^-$ predicts the characteristic polarization for the final state lepton. Lepton polarization has, in addition to a longitudinal component $P_L$, two orthogonal components $P_T$ and $P_N$ lying in and perpendicular to the decay plane. In this article we perform a study of the $τ$-polarisation asymmetry in the case of SUSY models with large $\tanβ$ in the inclusive decay $B \to X_s τ^+ τ^-$.

hep-ph↗
arXiv1998

Backgound Gluon Effects on B -> X_s gamma gamma

We consider non-perturbative QCD effects on the energy spectrum of either one of the photons in B -> X_s gamma gamma. These are due to the subprocesses in which a charm quark loop interacts with a self-consistently produced background static QCD field. The magnitude is estimated to be a few percents in B -> X_s gamma gamma, but can be quite substantial in B_s -> gamma gamma. An extension of the Euler-Heisenberg Lagrangian is given.

hep-ph↗
arXiv1997

Forward-Backward Asymmetry in $B\to X_d e^+e^-$

The Forward-backward asymmetry in the angular distribution of $e^+e^-$ is studied in the process $B\to e^+e^- and \bar{B}\to \bar{X}_d e^+e^-$ . The possibility of observing CP violation through the asymmetries in these two processes is examined.

hep-ph↗