arXiv subjects

Rupak Dutta

Publications and source records attributed to Rupak Dutta.

At least 19 recordsLinked to original sources

arXiv2024

Bottom-up approach to texture zeros in the neutrino mass matrix

We investigate one and two texture zeros in the neutrino mass matrix using the latest oscillation data through a bottom-up approach. In this context, we begin by estimating the detailed features of each matrix element by varying the CP violating phases within $(0,\,2\pi)$, the lowest neutrino mass within $(0,\,1)\,{\rm eV}$ and the neutrino oscillation parameters such as three mixing angles and the two mass squared differences within $3\sigma$ of their central values. We find that for normal ordering, only $ee$, $e\mu$ and $e\tau$ elements of the mass matrix can vanish, whereas, for inverted ordering, five elements -- $e\mu$, $e\tau$, $\mu\mu$, $\mu\tau$ and $\tau\tau$ -- can vanish. For two texture zeros, only $(ee,\, e\mu = 0)$ and $(ee,\, e\tau =0)$ are allowed in case of normal ordering. For a particular vanishing element, we also estimate the range of the lowest neutrino mass and the CP violating phases. In particular, very interesting correlation among the CP violating phases and the lowest neutrino mass is obtained for each vanishing cases.

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arXiv2024

Phenomenological study of two minor zeros in neutrino mass matrix using trimaximal mixing

We study the phenomenological implications of two minor zeros in neutrino mass matrix using trimaximal mixing matrix. In this context, we analyse fifteen possible cases of two minor zeros in neutrino mass matrix and found only two cases, namely Class $A_1$ and Class $A_2$, that are compatible with the present neutrino oscillation data. We present correlations of several neutrino oscillation parameters and give prediction of the total neutrino mass, the values of effective Majorana mass, the effective electron anti-neutrino mass and CP violating Majorana phases for these two classes. We also explore the degree of fine tuning in the elements of neutrino mass matrix for the allowed classes. Moreover, we propose a flavor model within the seesaw model along with $Z_{8}$ symmetry group that can generate such classes.

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arXiv2023

One vanishing minor in neutrino mass matrix using trimaximal mixing

We investigate the implications of one vanishing minor in neutrino mass matrix using trimaximal mixing matrix. In this context, we analyse all six patterns of one vanishing minor zero in neutrino mass matrix and present correlations of the neutrino oscillation parameters. All the six patterns are found to be phenomenologically viable with the present neutrino oscillation data. We also predict the values of effective Majorana mass, the effective electron anti-neutrino mass and the total neutrino mass for all the patterns. The value obtained for the effective neutrino mass is within the reach future neutrinoless double $β$ decay experiments. We also propose a flavor model where such patterns can be generated within the seesaw model.

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arXiv2023

Consequences of $b\, \to\, s\, μ^+\, μ^-$ anomalies on $B \, \to \, K^{(*)} \,ν\, \barν$, $B_s \to\, (η,η') \, ν\,\barν$ and $B_s \, \to \, ϕ\, ν\, \barν$ decay observables

The long persistent discrepancies in $b\,\to\,s\, \ell\, \ell$ quark level transitions continue to be the ideal platform for an indirect search of new physics that lies beyond the SM. The measurements of $R_K$, $R_{K^*}$, $P_5^{\prime}$, $\mathcal{B}(B_s\, \to\, ϕ\, μ^+\,μ^-)$ and $\mathcal{B}(B_s\, \to\, μ^+\,μ^-)$ persistently deviate from the standard model expectations. Similarly, the new tests of lepton flavor universality performed using the isospin partners such as $B^0 \, \to \, K_S^{0} \, \ell\,\ell$ and $B^+ \, \to \, K^{+*} \, \ell\,\ell$ exhibit the same pattern of deviation in $R_{K_S^0}$ and $R_{K^{*+}}$ with the existing results. Motivated by these anomalies we search for the patterns of new physics in the family of flavor changing neutral decays with neutral leptons in the final state undergoing $b \, \to \,s\, ν\, \barν$ quark level transitions. There are close relations between $b\,\to\,s\, \ell\, \ell$ and $b \, \to \,s\, ν\, \barν$ transitions not only in standard model but also in various beyond the standard model scenarios. For beyond the standard model physics under the $\rm SU_L(2)$ gauge symmetry one can relate the left handed charged leptons to the neutrinos. Moreover, there are several advantages of studying $b \, \to \,s\, ν\, \barν$ transitions over $b\,\to\,s\, \ell\, \ell$ as they are free from various hadronic uncertainties beyond the form factors such as the non-factorizable corrections and photonic penguin contributions. Hence, we explore the consequences of $b\, \to\, s\, μ^+\, μ^-$ anomalies on $B \, \to \, K^{(*)} \,ν\, \barν$, $B_s \to\, (η,η') \, ν\,\barν$ and $B_s \, \to \, ϕ\, ν\, \barν$ decay observables in SMEFT platform within various 1D and 2D new physics scenarios.

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arXiv2023

Combined analysis of $B_c \to D_s^{()}\,μ^+ μ^-$ and $B_c \to D_s^{()}\, ν\barν$ decays within $Z^{\prime}$ and leptoquark new physics models

We investigate the exclusive rare semileptonic decays $ B_c \to D_{s}^{(*)}\,(\ell \ell, ν\barν)$ induced by neutral current transition $b \to s (\ell \ell,ν\barν)$ in the presence of non-universal $Z^{\prime}$, scalar and vector leptoquark new physics models. We constrain the new physics parameter space by using the latest experimental measurements of $R_{K^{(*)}}$, $P_5^{\prime}$, $\mathcal{B}(B_s \to ϕμ^+ μ^-)$ and $\mathcal{B}(B_s \to μ^+ μ^-)$. Throughout the analysis, we choose to work with the particular new physics scenario $C_9 ^{μμ}(NP)=-C_{10} ^{μμ}(NP)$ where both $Z^{\prime}$, $S_{1/3}^3$ and $U_{-2/3}^3$ leptoquarks satisfy the condition. Using these new coupling parameters we scrutinize the several physical observables such as differential branching fraction, the forward backward asymmetry, the lepton polarization asymmetry, the angular observable $P^{\prime}_5$ and the lepton flavor universal sensitive observables including the ratio of branching ratio $R_{D_s^{(*)}}$ and the few $Q$ parameters in the $B_c \to D_s^{(*)}\,μ^+ μ^-$ and $B_c \to D_s^{(*)}\, ν\barν$ decay processes.

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arXiv2023

New physics analysis of $Λ_b\to (Λ^*(\to pK^-), Λ(\to pπ))(μ^{+}μ^{-},\,ν\barν)$ baryonic decays under SMEFT framework

The di-leptons and di-neutrinos observed in the final states of flavor-changing neutral b decays provide an ideal platform for probing physics beyond the standard model. Although the latest measurements of $R_{K^{(*)}}$ agree well with the standard model prediction, there exists several other observables such as $P_5^{\prime}$, $\mathcal{B}(B_s\to ϕμ^{+}μ^{-})$ and $\mathcal{B}(B_s\to μ^{+}μ^{-})$ in $b\to s \ell\ell$ transition decays that shows deviation from the standard model prediction. Similalry, very recently Belle II collaboration reported a more precise upper bound of $\mathcal{B}(B\to K^+ν\barν) < 4.1\times 10^{-5}$ by employing a new inclusive tagging approach and it also deviates from the standard model expectation. The $b\to s l^{+}l^{-}$ and $b\to sν\barν$ transition decays are related not only in the standard model but also in beyond the standard model physics due to $SU(2)_L$ gauge symmetry, and can be most effectively investigated using the standard model effective field theory formalism. Additionally, the $b\to sν\barν$ decay channels are theoretically cleaner than the corresponding $b\to s l^{+}l^{-}$ decays, as these processes do not get contributions from non-factorizable corrections and photonic penguin contributions. In this context, we study $Λ_b\to (Λ^*(\to pK^-), Λ(\to pπ))(μ^{+}μ^{-},\,ν\barν)$ baryonic decays undergoing $b\to s \ell^{+}\ell^{-}$ and $b\to sν\barν$ quark level transitions in a standard model effective field theory formalism. We give predictions of several observables pertaining to these decay channels in the standard model and in case of several new physics scenarios.

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arXiv2023

Status of G2HDM with right handed neutrino coupling in the light of $b\to c \tau\nu$ anomalies

Recent experimental measurements of several observables in semileptonic B meson decays have pointed towards the possibility of new physics. The LHCb collaboration has reported a significant deviation, exceeding $3.2\sigma$, in the combined measurement of the ratio of branching ratios $R(D)-R(D^\star)$ from the predictions of the standard model. Furthermore, other observables, such as $R_{J/\psi}$, $P_{\tau}^{D^\star}$, $F_L^{D^\star}$, and $R_{\Lambda_c}$ in the $b\to c\ell\nu$ transition, have also exhibited noticeable deviations from the standard model predictions. Motivated by these anomalies in the $b\to c\tau\nu$ transitions, we perform a log-likelihood fit incorporating new physics coming from right-handed neutrino couplings and explored the implications of a charged Higgs boson within a generic two Higgs doublet model (G2HDM). Our comprehensive analysis, focused on the $\tau\nu$ and $b\tau\nu$ final states, was performed using the High Luminosity run of the Large Hadron Collider (HL-LHC). We demonstrate that HL-LHC has the sensitivity to exclude the remaining allowed region in G2HDM model in explaining these anomalies with charged Higgs boson coupled to right-handed neutrino.

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arXiv2021

New physics footprints in the angular distribution of $B_s\to D_s^*(\to D_sγ,\,D_sπ)\, τ\, ν$ decays

Hints of lepton flavor universality violation observed in various flavor ratios such as $R_D$, $R_{D^*}$, $R_{J/ψ}$, $P_τ^{D^*}$ and $F_L^{D^*}$ in $B\to D^{(*)}\,\ell \, ν$ and $B_c\to J/ψ\, \ell\, ν$ charge current decays have opened new avenues to search for indirect evidences of beyond the standard model physics. Motivated by these anomalies, we perform a detailed angular analysis of $B_s\to D_s^*(\to D_sγ,\,D_sπ)\, \ell\, ν$ decays that proceed via similar $b \to c\, \ell\, ν$ quark level transition. We use the most general effective Hamiltonian for $b\to \,c\, lν$ process and give predictions of several $q^2$ and $\cosθ$ dependent observables for the $B_s\to D_s^*(\to D_sγ,\,D_sπ)\, \ell\, ν$ decays in the standard model and in the presence of various real and complex new physics couplings. The results pertaining to this decay are competent to address the anomalies in the charge current sector.

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arXiv2021

Angular analysis of $B_s\, \to\, f_{2}'\,(1525)\,(\to K^+\,K^-)\,μ^+ \,μ^-$ decays as a probe to lepton flavor universality violation

The flavor anomalies reported in $R_K$, $R_{K^*}$, $P_{5}^{\prime}$ and $\mathcal{B}(B_s\, \to\, ϕ\, μ^+\, μ^-)$ indicate lepton flavor universality violation in $b \to s\,l^+\,l^-$ quark level transition decays. The deviation from the SM prediction reported in the underlying flavor observables currently stand at the level of $2.5σ$, $2.4σ$, $3.3σ$ and $3.7σ$, respectively. In this context, we perform an angular analysis of the four-body differential decay of $B_s\, \to\, f_{2}^{\prime}\,(1525)\,(\to K^+\,K^-)\,μ^+ \,μ^-$ in a model independent effective field theory framework. The decay mode $B_s\, \to\, f_{2}^{\prime}(1525)\,l^+\,l^-$ undergoes similar $b \to s$ neutral current quark level transition and, in principle, can provide complementary information regarding lepton flavor universality violation in $b \to s\,l^+\,l^-$ quark level transition decays. We give predictions of various physical observables such as the branching ratio, the longitudinal polarization fraction, the forward-backward asymmetry, the angular observables $P_1$, $P_2$, $P_{4}^{\prime}$, $P_{5}^{\prime}$ and also the lepton flavor sensitive observables such as the ratio of branching ratio $R_{f_{2}^{\prime}}$, $Q_{F_L}$, $Q_{A_{FB}}$, $Q_{1}$, $Q_{2}$, $Q_{4}^{\prime}$, $Q_{5}^{\prime}$ for $B_s\, \to\, f_{2}^{\prime}\,(1525)\,(\to K^+\,K^-)\,μ^+ \,μ^-$ decays in the standard model and in the presence of several 1D and 2D new physics scenarios.

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arXiv2019

Implication of $b \to cτν$ flavor anomalies on $B_s\rightarrow {D_s^*}τν$ decay observables

The experimental predictions of $R_D$, $R_{D^*}$, $R_{J/ψ}$, $P_τ^{D^*}$ and $F_L^{D^*}$ in $B$ decays mediated via $b\,\to\, c\, l\,ν$ quark level transition deviate significantly from the standard model expectations. The current world average of the ratio of branching ratios $R_D$ and $R_{D^*}$ in $B\,\to\, D^{(*)}\, l\,ν$ ($l\in e,τ$) show $1.4σ$ and $2.5σ$ deviation from the SM expectations. Similarly, the $τ$ polarization fraction $P_τ^{D^*}$ and the longitudinal polarization fraction of the $D^*$ meson $F_L^{D^*}$ in $B\,\to\, D^*\,τ\,ν$ are found to deviate from the standard model expectations at $1.6σ$ and $1.5σ$ level, respectively. In addition, the ratio of branching ratio $R_{J/ψ}$ in $B_c\,\to\,{J/ψ}\, l\,ν$ deviates from the standard model prediction at $2σ$ level. In this regard, we study the implication of $R_D$, $R_{D^*}$, $R_{J/ψ}$, $P_τ^{D^*}$, and $F_L^{D^*}$ anomalies on $B_s\,\to\, {D^*_s}\,τ\,ν$ decay observables in a model independent effective field theory formalism. We give predictions of several physical observables in the standard model and in the presence of various $1D$ and $2D$ new physics scenarios.

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arXiv2019

Signature of lepton flavor universality violation in $B_s \to D_s τν$ semileptonic decays

Deviation from the standard model prediction is observed in many semileptonic $B$ decays mediated via $b \to c$ charged current interactions. In particular, current experimental measurements of the ratio of branching ratio $R_D$ and $R_{D^{\ast}}$ in $B \rightarrow D^{(*)}l ν$ decays disagree with standard model expectations at the level of about $4.1σ$. Moreover, recent measurement of the ratio of branching ratio $R_{J/Ψ}$ by LHCb, where $R_{J/Ψ} = \mathcal B(B_c \to J/Ψ\,τν)/\mathcal B(B_c \to J/Ψ\,μν)$, is more than $2σ$ away from the standard model prediction. In this context, we consider an effective Lagrangian in the presence of vector and scalar new physics couplings to study the implications of $R_D$ and $R_{D^{\ast}}$ anomalies in $B_s \to D_s\,τν$ decays. We give prediction of several observables such as branching ratio, ratio of branching ratio, forward backward asymmetry parameter, $τ$ polarization fraction, and the convexity parameter for the $B_s \to D_s\,τν$ decays within the standard model and within various new physics scenarios.

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arXiv2019

Probing new physics in $B_s \to (K,K^*)τν$ and $B \to πτν$ decays

Motivated by the anomalies present in $b \to u$ and $b \to c$ semileptonic decays, we study the corresponding $B_s \to (K,K^*) τν$ and $B \to πτν$ decays within an effective field theory formalism. Our analysis is based on a strict model dependent assumption, i.e., we assume that $b \to u$ and $b \to c$ transition decays exhibit similar new physics pattern. We give prediction of various observables such as the branching fraction, ratio of branching ratio, lepton side forward-backward asymmetry, longitudinal polarization fraction of the charged lepton and convexity parameter in the standard model and in the presence of vector type new physics couplings.

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arXiv2019

Model independent analysis of New Physics effects on $B_c \to (D_s,\,D^{\ast}_s)\,μ^+μ^-$ decay observables

Motivated by the anomalies present in $b \to s\,l^+\,l^-$ neutral current decays, we study the corresponding $B_c \to (D_s,\,D^{\ast}_s)μ^+μ^-$ decays within the standard model and beyond. We use a model independent effective theory formalism in the presence of vector and axial vector new physics operators and study the implications of the latest global fit to the $b \to s\,l^+\,l^-$ data on various observables for the $B_c \to (D_s,\,D^{\ast}_s)μ^+μ^-$ decays. We give predictions on several observables such as the differential branching ratio, ratio of branching ratios, forward backward asymmetry, and the longitudinal polarization fraction of the $D^{\ast}_s$ meson within standard model and within various new physics scenarios. These results can be tested at the Large Hadron Collider and, in principle, can provide complimentary information regarding new physics in $b \to s\,l^+\,l^-$ neutral current decays.

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arXiv2019

Implication of $R_{D^{(*)}}$ anomalies on semileptonic decays of $Σ_b$ and $Ω_b$ baryons

The flavor changing decays of heavy bottom quarks to the corresponding lighter quarks ($u$, $c$ and $s$) in various $B$-meson decays via charged current and neutral current semileptonic transitions have emerged as promising candidates to explore the physics beyond the standard model. Experimentally the lepton flavor universality violation in $b \to (c,u)\,l\,ν$ and $b \to s\,l^+ l^-$ transitions have been reported to a higher precision. The measurements of the lepton flavor violating ratios such as $R_{D^{(*)}}$, $R_{J/Ψ}$ and $R_{K^{(*)}}$ are observed to deviate from the standard model expectations at the level of $1.4σ$, $2.5σ$, $1.5σ$, $2.4σ$ and $2.2σ$ respectively. Motivated by these anomalies, we investigate the lepton flavor universality violation in $Σ_b \to Σ_c l ν$ and $Ω_b \to Ω_c l ν$ decays. We follow a model independent effective field theory formalism and study the implications of $R_{D^{(*)}}$ anomalies on $Σ_b \to Σ_c τν$ and $Ω_b \to Ω_c τν$ decay modes. We give predictions of various physical observables such as the ratio of branching ratios, total differential decay rate, forward-backward asymmetry, lepton side polarization fraction and convexity parameter within the standard model and within various new physics scenarios.

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arXiv2018

Predictions of $B_c \to (D,\,D^{\ast})\,l\,ν$ decay observables in the standard model

We study $B_c \to (D,\,D^{\ast})\,l\,ν$ semileptonic decays mediated via $b \to u\,l\,ν$ charged current interactions using the $B_c \to (D,\,D^{\ast})$ transition form factors obtained in the covariant light front quark model. We give predictions on the branching ratios, ratio of branching ratios, and various asymmetries pertaining to these decay modes within the standard model. These results can be tested in the ongoing or in the future experiments and can provide complimentary information regarding the observed anomalies in $B \to (D,\,D^{\ast})τν$ and $B_c \to J/Ψτν$ decays.

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arXiv2018

Impact of vector new physics couplings on $B_s \to (K,\,K^{\ast})τν$ and $B \to πτν$ decays

Experimental measurements of $R_{D}$, $R_{D^*}$ and $R_{J/Ψ}$ in $B \to (D,\,D^{\ast})lν$ and $B_c \to J/Ψl ν$ decays mediated via $b \to c\,l\,ν$ charged current interactions deviate from standard model prediction by $2.3σ$, $3.4σ$ and $2σ$, respectively. In addition, a deviation of $1.5σ$ from the standard model prediction has been witnessed in $\mathcal B(B \to τν)$ mediated via $b \to u\,l\,ν$ charged current interactions as well. Motivated by the anomalies present in $B$ and $B_c$ meson decays, we analyze the corresponding $B_s \to (K,\,K^{\ast})\,τ\,ν$ and $B \to πτν$ semileptonic decays within the standard model and beyond. We use an effective field theory formalism in which $b \to c$ and $b \to u$ semileptonic decays are assumed to exhibit similar new physics patterns. We give the predictions of various observables such as the branching fractions, ratio of branching ratios, lepton side forward backward asymmetry, lepton polarization fraction and convexity parameter for $B_s \to (K,\,K^{\ast})τν$ and $B \to πτν$ decay channels within the standard model and within various NP scenarios.

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arXiv2018

Signature of Lepton flavor universality violation in $B_s \to D_sτν$ semileptonic decays

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arXiv2018

Phenomenology of $Ξ_b \to Ξ_c\,τ\,ν$ decays

Deviations from the standard model prediction have been reported in various semileptonic $B$ decays mediated via $b \to c$ charged current interactions. In this context, we analyze semileptonic baryon decays $Ξ_b \to Ξ_c\,τ\,ν$ using the helicity formalism. We report numerical results on various observables such as the decay rate, ratio of branching ratio, lepton side forward backward asymmetries, longitudinal polarization fraction of the lepton, and the convexity parameter for this decay mode using results of relativistic quark model. We also provide an estimate of the new physics effect on these observables under various new physics scenarios.

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