arXiv subjects

Suchismita Sahoo

Publications and source records attributed to Suchismita Sahoo.

31 records · Page 2Linked to original sources

arXiv2018

Impact of vector leptoquark on $\bar B \to \bar K^* l^+ l^-$ anomalies

Motivated by the recent measurement of the lepton flavour nonuniversality ratio $R_{K^*}$ by the LHCb Collaboration, we study the implications of vector leptoquarks on the observed anomalies associated with the $\bar B \to \bar K^* l^+ l^-$ decay processes. The leptoquark couplings are constrained from the measured branching ratios of $B_s \to l^+ l^-$, $K_L \to l^+ l^-$ and $B_s \to μ^\mp e^\pm$ processes. Using these constrained couplings, we estimate the branching ratios, forward-backward and lepton polarization asymmetries and also the form factor independent optimized observables ($P_{i}^{(\prime)}$) for $\bar B \to \bar K^* l^+ l^-$ modes in the high recoil limit. We also study the other lepton flavour universality violating observables, such as $Q_{F_{L, T}}$, $Q_{i}$ and $B_{5, 6s}$, where $i=1,2,\cdots6, 8$. Furthermore, we investigate the lepton flavour violating $K_L \to μ^\mp e^\pm$ decay process in this model.

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arXiv2017

Model independent investigation of rare semileptonic b \to u l \barν_l decay processes

Motivated by the recent observation of lepton universality violation in the flavour changing charged current transitions $b \to c l \barν_l$, we intend to scrutinize the lepton non-universality effects in rare semileptonic $B$ meson decays involving the quark level transitions $b \to u l \barν_l$. In this regard, we envisage the model-independent approach and consider the generalized effective Lagrangian in the presence of new physics and constrain the new parameters by using the experimental branching fractions of $B_u^+ \to l^+ ν_l$ and $B^- \to π^0 μ^- \bar ν_μ$ processes, where $l=e, μ, τ$. We then estimate the branching ratios and forward-backward asymmetries of $B_{(s)} \to P (V)l \barν_l$ processes, where $P(=K, π, η^{(\prime)})$ denotes the pseudoscalar meson and $V(=K^*, ρ)$ is the vector meson. We also find out various lepton non-universality parameters in these processes in the presence of new physics.

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arXiv2017

Study of the rare decays $B_{s,d}^* \to μ^+ μ^-$

We study rare leptonic decays of vector $B$ mesons in the scalar leptoquark and family non-universal $Z^\prime$ models. We constrain these new couplings by using the measured branching fractions of $B_{s,d} \to μ^+ μ^-$ processes and the existing $B_{s,d}^0-\bar B_{s,d}^0$ mixing data. We estimate the branching fractions of $B_{s,d}^* \to μ^+ μ^-$ in both the models, which are found to be reasonably enhanced from their corresponding standard model values and within the reach of Run 2-3 of LHC.

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arXiv2017

New Physics effects in charm meson decays involving $c \to u l^+ l^- (l_i^\mp l_j^\pm)$ transitions

We study the effect of scalar leptoquark and $Z^\prime$ boson on the rare decays of $D$ mesons involving flavour changing transitions $c \to u l^+ l^- (l^\mp_i l^\pm_j)$. We constrain the new physics parameter space using the branching ratio of the rare decay mode $D^0 \to μ^+ μ^-$ and the $D^0-\bar D^0$ oscillation data. We compute the branching ratios, forward-backward asymmetry parameters and flat terms in $D^{+(0)} \to π^{+(0)} μ^+ μ^-$ processes using the constrained parameters. The branching ratios of the lepton flavour violating $D$ meson decays, such as $D^0 \to μe, ~τe$ and $D^{+(0)} \to π^{+(0)} μ^- e^+$ are also investigated.

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arXiv2017

Explaining the $R_{K}$ and $R_{D^{(*)}}$ anomalies with vector leptoquarks

Recently the $B$ factories BaBar and Belle as well as the LHCb experiment have reported several anomalies in the semileptonic $B$ meson decays such as $R_{K}$ and $R_{D^{(*)}}$ etc. We investigate these deviations by considering the vector leptoquarks relevant for both $b \to s l^+ l^-$ and $b \to c l \bar ν_l$ transitions. The leptoquark parameter space is constrained by using the experimentally measured branching ratios of $B_s \to l^+ l^-$, $\bar B \to X_s l^+ l^- (ν\bar ν)$ and $B_u^+ \to l^+ ν_l$ processes. Using the constrained leptoquark couplings, we compute the branching ratios, forward-backward asymmetries, $τ$ and $D^*$ polarization parameters in the $\bar B \to D^{(*)} l \bar ν_l$ processes. We find that the vector leptoquarks can explain both $R_{D^{(*)}}$ and $R_K$ anomalies simultaneously. Furthermore, we study the rare leptonic $B_{u, c}^* \to l \barν$ decay processes in this model.

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arXiv2017

Rare semileptonic $B \to K(π)l_i^- l_j^+$ decay in vector leptoquark model

We investigate the consequence of vector leptoquarks on the rare semileptonic lepton flavour violating decays of $B$ meson which are more promising and effective channels to probe the new physics signal. We constrain the resulting new leptoquark parameter space by using the branching ratios of $B_{s, d} \to l^+ l^-$, $K_L \to l^+ l^-$ and $τ^- \to l^- γ$ processes. We estimate the branching ratios of rare lepton flavour violating $B \to K(π)l_i^- l_j^+$ processes using the constrained leptoquark couplings. We also compute the forward-backward asymmetries and the lepton non-universality parameters of the LFV decays in the vector leptoquark model. Furthermore, we study the effect of vector leptoquark on $(g-2)_μ$ anomaly.

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arXiv2017

Impact of leptoquarks in semileptonic B decays

We study the impact of vector leptoquarks on the recent anomalies in semileptonic $B$ meson decays such as $R_K$ and $R_{D^{(*)}}$ etc. We constrain the leptoquark couplings by using the existing data on the branching ratios of $B_s \to l^+ l^-$ and $\bar{B} \to X_s l^+ l^-$ processes, where $l=e,μ,τ$. We estimate the branching ratios of $\bar B \to D^{(*)} l \bar ν_l$ processes using the constrained leptoquark parameter space. We also investigate the possibility of simultaneous explanation of $R_{D^{(*)}}$, $R_K$ anomalies in this model.

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arXiv2016

Study of the rare decays $B_{s,d}^* \to μ^+ μ^-$

We investigate the effect of scalar leptoquarks and family non-universal $Z^\prime$ boson on the rare leptonic decays of $B_{s, d}^*$ mesons, mediated by the FCNC transitions $b \to (d, s) l^+ l^-$. They are sensitive to a variety of new physics operators as opposed to the $B_{s,d}$ leptonic modes and hence, can provide an ideal testing ground to look for new physics beyond the standard model. We work out the constraint on new physics parameter space using the measured branching ratios of $B_{d, s} \to μ^+ μ^-$ processes and the $B_q - \bar B_q$ mixing data. Using the constrained parameters we estimate the branching ratios of $B_{d,s} \to μ^+ μ^-~(e^+ e^-)$ processes. We find that the branching ratios are reasonably enhanced from their corresponding standard model values in the $X(3,2,1/6)$ leptoquark model and are expected to be within the reach of Run II/III of LHC experiments.

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arXiv2016

Effects of scalar leptoquark on semileptonic $Λ_b$ decays

We study the scalar leptoquark effects on the rare semileptonic decays of $Λ_b$ baryon, governed by the quark level transition $b \to s l^+ l^-$. We estimate the branching ratios, forward-backward asymmetries, lepton polarization parameters and the lepton flavour non-universality effects in these decay channels. We find significant deviations from the corresponding standard model predictions in some of the observables due to leptoquark effects. We also investigate the lepton flavour violating decays $Λ_b \to Λl_i^- l_j^+$, the branching ratios of which are found to be ${\cal O}(10^{-10} - 10^{-9})$.

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arXiv2016

Lepton flavour violating B meson decays via scalar leptoquark

We study the effect of scalar leptoquarks in the lepton flavour violating $B$ meson decays induced by the flavour changing transitions $b \to q l_i^+ l_j^-$ with $q=s,d$. In the standard model these transitions are extremely rare as they are either two-loop suppressed or proceed via box diagrams with tiny neutrino masses in the loop. However, in the leptoquark model they can occur at tree level and are expected to have significantly large branching ratios. The leptoquark parameter space is constrained using the experimental limits on the branching ratios of $B_q \rightarrow l^+ l^-$ processes. Using such constrained parameter space, we predict the branching ratios of LFV semileptonic $B$ meson decays, such as $B^+ \to K^+ (π^+) l_i^+ l_j^-$, $B^+ \to (K^{* +}, ρ^+) l_i^+ l_j^-$ and $B_s \to ϕl_i^+ l_j^-$, which are found to be within the experimental reach of LHCb and the upcoming Belle II experiments. We also investigate the rare leptonic $K_{L, S} \to μ^+ μ^- (e^+ e^-)$ and $K_{L} \to μ^\mp e^\pm$ decays in the leptoquark model.

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arXiv2016

Study of the rare semileptonic decays $B_d^0 \to K^* l^+ l^-$ in scalar leptoquark model

We study the effect of scalar leptoquarks on the exclusive rare $B$ meson decays $\bar{B}_d^0 \rightarrow \bar{K}^{* 0}\left(\rightarrow K^-π^+\right) l^+ l^-$ in the full kinematically accessible physical region. We work out the constraints on leptoquark parameter space using the measured branching ratio of $B_s \rightarrow μ^+ μ^-$ process by the CMS and LHCb collaborations. We compute the branching ratio, forward-backward asymmetry and isospin asymmetry distribution using the constrained parameter space. We also look into various form factor independent and CP violating observables in the scalar leptoquark model.

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arXiv2016

Leptoquark effects on $b \to s ν\barν$ and $B \to K l^+ l^-$ decay processes

We study the rare semileptonic decays of $B$ mesons induced by $b \to s ν\barν$ as well as $b \to s l^+ l^-$ transitions in the scalar leptoquark model where the leptoquarks transform as $(3,2,7/6)$ and $(3,2,1/6)$ under the standard model gauge group. The leptoquark parameter space is constrained using the most recent experimental results on ${\rm Br}(B_s \rightarrow μ^+ μ^-)$ and ${\rm Br}(B_d \to X_s μ^+ μ^-)$ processes. Considering only the baryon number conserving leptoquark interactions, we estimate the branching ratios for the exclusive $\bar{B} \rightarrow \bar{K}^{(*)} ν\barν$ and inclusive $B \rightarrow X_s ν\barν$ decay processes by using the constraint parameters. We also obtain the low recoil (large lepton invariant mass, i.e., $q^2 \sim m^2_b$) predictions for the angular distribution of $\bar B \rightarrow \bar{K} l^+ l^-$ process and several other observables including the flat term and lepton flavour non-universality factor in this model.

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arXiv2015

Scalar leptoquarks and the rare B meson decays

We study some rare decays of $B$ meson involving the quark level transition $b \to q l^+l^- (q=d,s)$ in the scalar leptoquark model. We constrain the leptoquark parameter space using the recently measured branching ratios of $B_{s,d} \to μ^+ μ^-$ processes. Using such parameters, we obtain the branching ratios, direct CP violation parameters and isospin asymmetries in $B \to K μ^+ μ^-$ and $B \to πμ^+ μ^-$ processes. We also obtain the branching ratios for some lepton flavour violating decays $B \to l_i^+ l_j^-$. We find that the various anomalies associated with the isospin asymmetries of $B \to K μ^+ μ^-$ process can be explained in the scalar leptoquark model.

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