Implications of lepton nonuniversality in the beauty sector

The phenomenon of CP violation in the standard model (SM) framework and the decay dynamics have been established from the data obtained from the B factories and so far we have not seen anything new. Nevertheless, there have been instances of deviations in many measured observables in the flavor sector, as far as the data and predictions are concerned. Here we will mention some deviations obtained in measurements related to lepton universality, as seen from the data, and try to understand their implications. To accommodate the observed data we will consider a leptoquark model, which seems to be one interesting model beyond the SM.Comment: 6 pages, 4 figures, talk given at BEACH 2016, George Mason University, Fairfax, Virginia, USA, June 201

Implications of the non-universal Z boson in FCNC mediated rare decays

We analyze the effect of the non-universal $Z$ boson in the rare decays $B_s \to l^+ l^-$, $B_s \to l^+ l^- \gamma$ and $Z \to b \bar s$ decays. These decays involve the FCNC mediated $b \to s$ transitions, and are found to be very small in the standard model. The smallness of these decays in the standard model makes them sensitive probe for new physics. We find an enhancement of at least an order in these branching ratios because of the non-universal $Zbs$ coupling.Comment: 15 pages, 4 figures, minor changes in the text, references added, to appear in PR

Weak phase information from the color suppressed B_d^0 -> D^{*0} K^{*0} modes

The decay channels $B_d^0 \to D^{*0} K^{*0}$ are investigated for extracting weak $CKM$ phase information. These channels are described by color-suppressed tree diagrams only and are free from penguin contributions. The branching ratios for these channels are found to be $\sim \cal O$ $(10^{-5} - 10^{-6})$ which can be measured at the currently running $B$ factories. The method presented here may be well-suited to determine the phase $\gamma$.Comment: 11 pages, revised extensively, version to appear in Phys. Rev.

Charge Density Wave and Superconductivity in Transition Metal Dichalcogenides

Competing orders in condensed matter give rise to the emergence of fascinating, new phenomena. Here, we investigate the competition between superconductivity and charge density wave in the context of layered-metallic compounds, transition metal dichalcogenides, in which the superconducting state is usually suppressed by the charge density wave. We show, using real-space self-consistent Bogoliubov-de Gennes calculations and momentum-space calculations involving density-functional theory and dynamical mean-field theory, that there is a surprising reappearance of superconductivity in the presence of non-magnetic disorder fluctuations, as observed in recent experiments

Study of some rare decays of B_s meson in the fourth generation model

We study some rare decays of $B_s$ meson governed by the quark level transitions $b \to s$, in the fourth generation model popularly known as SM4. Recently it has been shown that SM4, which is a simple extension of the SM3, can successfully explain several anomalies observed in the CP violation parameters of $B$ and $B_s$ mesons. We find that in this model due to the additional contributions coming from the heavy $t'$ quark in the loop, the branching ratios and other observables in rare $B_s$ decays deviate significantly from their SM values. Some of these modes are within the reach of LHCb experiment and search for such channels are strongly argued.Comment: 21 pages, 5 figures, version to appear in Phys. Rev.