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Naveen Gaur

Publications and source records attributed to Naveen Gaur.

At least 37 records · Page 2Linked to original sources
arXiv2005

Signatures of new Physics in dileptonic B-decays

Leptonic decays of $B$-mesons are theoretically very clean probes for testing the Standard Model (SM) and possible physics beyond it. Amongst the various leptonic decays of the $B$-meson, the pure dileptonic decay $B \to \ell^+ \ell^-$ is very important as this mode is helicity suppressed in the SM but can be substantially enhanced in some of the models beyond the SM, such as supersymmetric (SUSY) theories and the two Higgs doublet model (2HDM). Although the purely dileptonic decay mode is helicity suppressed in the SM its associated mode $B \to \ell^+ \ell^- γ$ does not have the same suppression, due to the presence of the $γ$ in the final state. In this paper we will also analyse the effects of enhanced $Z$-penguins on these two decay modes.

hep-ph↗
arXiv2005

Lepton polarization asymmetries for $B \to K^* \ell^+ \ell^-$: A Model Independent approach

In this work we shall derive expressions for the single and double lepton polarization asymmetries for the exclusive decay $B \to K^* \ell^+ \ell^-$, using the most general model independent effective Hamiltonian. We have conducted this study with this particular channel as it has the highest branching ratio among the various purely leptonic and semi-leptonic decay modes, making this mode particularly useful for studying physics beyond the SM. We have also analyzed the effects on these polarization asymmetries, and hence the physics underlying it, when complex phases are included in some of the Wilson coefficients.

hep-ph↗
arXiv2005

$K_L \to π^0 ν\barν$ in Little Higgs model

Little Higgs models provides us a new solution of the {\it hierarchy problem} of the SM. The problem is associated with the large difference in scales of SM and plank scale. One of the main features of these models is the existence of a vector like top quark. The CP violating $K_L \to π^0 ν\barν$ process n the SM model is dominated by top quark penguin & box graphs. We examine this process in the Little Higgs model where the top quark sector has significant differences from the Standard Model.

hep-ph↗
arXiv2005

$B_d - \bar{B}_d$ mass difference in Little Higgs model

An alternate solution of hierarchy problem in the Standard Model namely, the Little Higgs model, has been proposed lately. In this work $B_d^0-\bar{B_d^0}$ mass difference in the framework of the Little Higgs model is evaluated. The experimental limits on the mass difference is shown to provide meaningful constraints on the parameter space of the model.

hep-ph↗
arXiv2004

The effects of enhanced Z penguins on lepton polarizations in $B \to X_s \ell^+ \ell^-$

The sensitivity of the $B \to πK$ mode to electroweak penguins and the recent experimental data for the $B \to ππ$, $πK$ modes has given rise to what is known as the ``$B \to πK$ puzzle''. Recently it has been observed that this {\sl puzzle} can be resolved by considering the new physics which can enter via $Z^0$ penguins. In this note we analyze the effect of this enhanced $Z^0$ penguins on the lepton polarization asymmetries of $b \to s \ell^+ \ell^-$.

hep-ph↗
arXiv2004

Supersymmetric effects on Forward Backward asymmetries of $B \to K \ell^+ \ell^-$

Leptonic and semi-leptonic rare decays of B-mesons are very clean (both theoretically and experimentally) signatures of any new physics beyond the Standard Model (SM). More specifically the decay \btokll has been theoretically observed to be very sensitive to new physics as the Forward Backward (FB) asymmetry in this decay mode vanishes in the SM. Supersymmetry, however, predicts a non-vanishing value of this asymmetry. In this work we will study the polarized lepton pair FB asymmetry, i.e. the FB asymmetry of the lepton when one (or both) final state lepton(s) are polarized. We will study these asymmetries both within the SM and for Supersymmetric corrections to the SM.

hep-ph↗
arXiv2003

The Forward Backward asymmetries of $B \to X_s τ^+ τ^-$ in the MSSM

The relatively clean theoretical probes of the Standard Model (SM), and the various theories beyond the SM, provided by radiative, semi-leptonic and (purely) leptonic decays of B-mesons have become increasingly important. Due to the large number of possible distributions in the semi-leptonic decays based on the quark level transition $b \to s \ell^+ \ell^-$ (not just the branching ratio), these transitions have become very useful. A study of the Forward-Backward asymmetries for the inclusive decay ($B \to X_s \ell^+ \ell^-$) is carried out in this paper. This study shall be performed in the SM and a minimal supersymmetric extensions of the SM, namely the mSUGRA model.

hep-ph↗
arXiv2003

Lepton polarization correlations in $B \to K^* τ^- τ^+$

In this work we will study the polarizations of both leptons ($τ$) in the decay channel $B\to K^* τ^- τ^+$. In the case of the dileptonic inclusive decay $B\to K^* \ell^- \ell^+$, where apart from the polarization asymmetries of single lepton $\ell$, one can also observe the polarization asymmetries of both leptons simultaneously. If this sort of measurement is possible then we can have, apart from decay rate, FB asymmetry and the six single lepton polarization asymmetries (three each for $\ell^-$ and $\ell^+$), nine more double polarization asymmetries. This will give us a very useful tool in more strict testing of SM and the physics beyond. We discuss the double polarization asymmetries of $τ$ leptons in the decay mode $B\to K^* τ^- τ^+$ within the SM and the Minimal Supersymmetric extensions of it.

hep-ph↗
arXiv2003

Lepton polarization asymmetries in $B \to X_s τ^+ τ^-$ in MSSM

Semi-leptonic and leptonic decays of B-mesons are important probes for testing SM and theories beyond it because of their relative cleanliness and far less theoretical uncertainties. In semi-leptonic decays based on quark level transition $b \to s τ^+ τ^-$ apart from branching ratio one can study many other (possible) observables associated with final state leptons like, lepton pair Forward Backward asymmetry, lepton polarization asymmetries etc. But as proposed recently if we can tag the B-meson than one can measure the polarization asymmetries of both the leptons. Here we will study the polarization asymmetries of both the final state leptons in SM and Minimal Supersymmetric Extension (MSSM) to it.

hep-ph↗
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↗
arXiv2001

Linearisation of Simple Pendulum

The motion of a pendulum is described as Simple Harmonic Motion (SHM) in case the initial displacement given is small. If we relax this condition then we observe the deviation from the SHM. The equation of motion is non-linear and thus difficult to explain to under-graduate students. This manuscript tries to simplify things.

physics.ed-ph↗
arXiv2001

How simple is simple pendulum

The simple pendulum is one of the first experiments that students of higher physics do. There are certain precautions which the students are asked to take while performing the experiment. In this note we will try to explain as to why these precautions are taken up and what will happen if we relax them.

physics.ed-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↗