The origin of small mixing among the quarks and a large mixing among the neutrinos has been an op... more The origin of small mixing among the quarks and a large mixing among the neutrinos has been an open question in particle physics. In order to answer this question, we postulate general relations among the quarks and the leptonic mixing angles at a high scale, which could be the scale of Grand Unified Theories. The central idea of these relations is that the quark and the leptonic mixing angles can be unified at some high scale either due to some quark-lepton symmetry or some other underlying mechanism and as a consequence, the mixing angles of the leptonic sector are proportional to that of the quark sector. We investigate the phenomenology of the possible relations where the leptonic mixing angles are proportional to the quark mixing angles at the unification scale by taking into account the latest experimental constraints from the neutrino sector. These relations are able to explain the pattern of leptonic mixing at the low scale and thereby hint that these relations could be poss...
Considering the recent experimental results on exclusive semileptonic B meson decays showing siza... more Considering the recent experimental results on exclusive semileptonic B meson decays showing sizable departure from their Standard Model prediction of lepton flavor universality and keeping ongoing and proposed non-standard Higgs searches in mind, we explore the charged current flavor observables (R_D^(*), R_J/ψ), among other b→ cℓν transitions, in the presence of a relevant scalar current effective new physics operator. We use B_c lifetime and predicted bounds on the branching fraction of B_c →τν decay as constraints. We show the allowed parameter space in terms of the real and imaginary parts of the corresponding Wilson coefficients for such interactions. Under the light of obtained results, we study the prospect of two benchmark models, rendering the Wilson coefficients real (Georgi-Machacek (GM)) and complex (Leptoquark (LQ)) respectively. We show that constraints from b→ cℓν on GM parameters are consistent with other flavor constraints on the model, if we drop the results. Incl...
To extract the Cabibbo-Kobayashi-Maskawa (CKM) matrix element |V_ub|, we have re-analyzed all the... more To extract the Cabibbo-Kobayashi-Maskawa (CKM) matrix element |V_ub|, we have re-analyzed all the available inputs (data and theory) on the B→π lν decays including the newly available inputs on the form-factors from light cone sum rule (LCSR) approach. We have reproduced and compared the results with the procedure taken up by the Heavy Flavor Averaging Group (HFLAV), while commenting on the effect of outliers on the fits. After removing the outliers and creating a comparable group of data-sets, we mention a few scenarios in the extraction of |V_ub|. In all those scenarios, the extracted values of |V_ub| are higher than that obtained by HFLAV. Our best results for |V_ub|^exc. are (3.88 ± 0.13)× 10^-3 and (3.87 ± 0.13)× 10^-3 in frequentist and Bayesian approaches, respectively, which are consistent with that extracted from inclusive decays |V_ub|^inc within 1 σ confidence interval.
In the light of recent data, we study the new physics effects in the exclusive b → s ℓ^+ℓ^- decay... more In the light of recent data, we study the new physics effects in the exclusive b → s ℓ^+ℓ^- decays from a model independent perspective. Different combinations of the dimension six effective operators along with their respective Wilson coefficients are chosen for the analysis. To find out the operator or sets of operators that can best explain the available data in this channel, we simultaneously apply popular model selection tools like cross-validation and the information theoretic approach like Akaike Information Criterion (AIC). There are one, two, and three-operator scenarios which survive the test and a left-handed quark current with vector muon coupling is common among them. This is also the only surviving one-operator scenario. Best-fit values and correlations of the new Wilson coefficients are supplied for all the selected scenarios. We find that the angular observables play the dominant role in the model selection procedure. We also note that while a left-handed quark curre...
The Leptoquark model has been instrumental in explaining the observed lepton flavour universality... more The Leptoquark model has been instrumental in explaining the observed lepton flavour universality violating charged ($b\to c$) and neutral current ($b\to s$) anomalies that have been the cause for substantial excitement in particle physics recently. In this article we have studied the role of one (designated as $V_2^{\frac 43}$) of the components of {\boldmath${V}_2$} vector leptoquark doublet with electromagnetic charge $\frac 43$ in explaining the neutral current ($b\to s$) anomalies $R_{K^{(*)}}$ and $B_s\to\mu^+\mu^-$. Moreover, we have performed a thorough collider search for this $V_2^{\frac 43}$ Leptoquark using $b\bar{b} \ell^+ \ell^-$ ($\ell\equiv e, \mu$) final state at the Large Hadron Collider. From our collider analysis we maximally exclude the mass of the $V_2^{\frac 43}$ Leptoquark up to 2340 GeV at 95\% confidence level for the 13 TeV Large Hadron Collider for an integrated luminosity of 3000 ${\rm fb}^{-1}$. Furthermore, a significant portion of the allowed paramete...
In a couple of recent publications ( arXiv:1706.08437 and arXiv:1712.01593 ), the authors attempt... more In a couple of recent publications ( arXiv:1706.08437 and arXiv:1712.01593 ), the authors attempted to achieve simultaneous explanation of the persistent flavor anomalies in b→ s and b→ c semileptonic decays with a minimal scheme by using only three unknown new parameters. The analysis was obtained with a handful of precise observables. Motivated by their proposal, in this paper we reanalyze the models proposed in the aforementioned papers with a total of 170 observables from those channels including newly available measurements, correlated theoretical results, and constraints. We validate our results by searching for the most influential points and outliers. By analyzing the parameter spaces and their relationship with the constraints, we gain new insight and statistical significance in those models. We also provide a new and precise calculation of R(J/Ψ), obtained during the analysis.
We show that for a heavy vector-like quark model with a down type isosinglet, branching ratio for... more We show that for a heavy vector-like quark model with a down type isosinglet, branching ratio for c→ uγ decay is enhanced by more than O(10^2) as compared to that in the Standard model when QCD corrections to next-to-leading order are incorporated. In a left-right symmetric model (LRSM) along with a heavy vector-like fermion, enhancement of this order can be achieved at the bare (QCD uncorrected) level itself. We propose that a measurement of the photon polarization could be used to signal the presence of such new physics inspite of the large long distance effects. We find that there is a large region within the allowed parameter space of model with vector-like quark with additional left-right symmetry, where depending on the exact size of the long distance contribution, the photon polarization can be dominantly right-handed.
We show that the hadronic "heat capacity" calculated as a function of temperature may b... more We show that the hadronic "heat capacity" calculated as a function of temperature may be used to infer the possible presence of different scales underlying the dynamical structure of hadronic resonances using the phenomenon of Schottky anomaly. We first demonstrate this possibility with well known meson spectrum in various channels and comment on the possibility of using this method as a diagnostic to distinguish the exotic states.
A possible diagnostic is proposed which may be used to infer the different scales underlying the ... more A possible diagnostic is proposed which may be used to infer the different scales underlying the dynamical structure of hadronic resonances using the phenomenon of Schottky anomaly.
We perform a model independent analysis of the charged current b→ clν anomalies under the presenc... more We perform a model independent analysis of the charged current b→ clν anomalies under the presence of scalar and vector interactions. The analysis is carried out in two stages: (a) under the presence of both (left-handed) vector and scalar interactions and (b) under the presence of scalar interactions alone. We find that even after stringent bounds from similar quark-level processes such as B_c→τν, such scenarios have the potential to explain the aforementioned anomalies. Contrary to the general notion, we show that even scalar interactions alone can explain such anomalies, provided they are complex. However, extended scalar sector models are unable to comply with these anomalies to ∼ 3σ. We further illustrate our results with the help of three benchmark models corresponding to the presence of (i) both scalar and vector (ii) real scalar and (iii) complex scalar interactions.
We estimate contributions from Kaluza-Klein excitations of gauge bosons and physical charge scala... more We estimate contributions from Kaluza-Klein excitations of gauge bosons and physical charge scalar for the explanation of the lepton flavor universality violating excess in the ratios R(D) and R(D^*) in 5 dimensional Universal Extra Dimensional scenario with non-vanishing boundary localized terms. This model is conventionally known as non-minimal Universal Extra Dimensional model. We obtain the allowed parameter space in accordance with constraints coming from B_c →τν decay, as well as those from the electroweak precision tests.
1The Institute of Mathematical Sciences, Chennai 600113, India (Dated: October 3, 2018) Abstract ... more 1The Institute of Mathematical Sciences, Chennai 600113, India (Dated: October 3, 2018) Abstract We show that the hadronic “heat capacity” calculated as a fun ctio of temperature may be used to infer the possible presence of different scales underlying the dynam ical structure of hadronic resonances using the phenomenon of Schottky anomaly. We first demonstrate this po s ibility with well known meson spectrum in various channels and comment on the possibility of using t his method as a diagnostic to distinguish the exotic states.
$B\To CL\Nu$ Anomalies in Light of Vector and Scalar Interactions
We perform a model independent analysis of the charged current $b\to cl\nu$ anomalies under the p... more We perform a model independent analysis of the charged current $b\to cl\nu$ anomalies under the presence of scalar and vector interactions. The analysis is carried out in two stages: (a) under the presence of both (left-handed) vector and scalar interactions and (b) under the presence of scalar interactions alone. We find that even after stringent bounds from similar quark-level processes such as $B_c\to\tau\nu$, such scenarios have the potential to explain the aforementioned anomalies. Contrary to the general notion, we show that even scalar interactions alone can explain such anomalies, provided they are complex. However, extended scalar sector models are unable to comply with these anomalies to $\sim 3\sigma$. We further illustrate our results with the help of three benchmark models corresponding to the presence of (i) both scalar and vector (ii) real scalar and (iii) complex scalar interactions.
A possible diagnostic is proposed which may be used to infer the different scales underlying the ... more A possible diagnostic is proposed which may be used to infer the different scales underlying the dynamical structure of hadronic resonances using the phenomenon of Schottky anomaly.
We perform a data-driven analysis of new physics (NP) effects in exclusive $b \to s \ell^+\ell^-$... more We perform a data-driven analysis of new physics (NP) effects in exclusive $b \to s \ell^+\ell^-$ decays in a model-independent effective theory approach with dimension six effective operators considering scalar, pseudo-scalar, vector, and axial-vector operators with the corresponding Wilson coefficients (WC) taken to be complex. The analysis has been done with the most recent data while comparing the outcome with that from the relatively old data-set. We find that a left-handed quark current with axial-vector muon coupling is the only one-operator $(\mathcal{O}_9)$ scenario that can explain the data in both the cases with real and complex WC with a large non-zero imaginary contribution. We simultaneously apply model selection tools like cross-validation and information theoretic approach like Akaike Information Criterion (AIC) to find out the operator or sets of operators that can best explain the available data in this channel. None of the one-operator scenarios with real WC survi...
To extract the Cabibbo-Kobayashi-Maskawa (CKM) matrix element |Vub|, we have re-analyzed all the ... more To extract the Cabibbo-Kobayashi-Maskawa (CKM) matrix element |Vub|, we have re-analyzed all the available inputs (data and theory) on the B → πℓν decays including the newly available inputs on the form-factors from light cone sum rule (LCSR) approach. We have reproduced and compared the results with the procedure taken up by the Heavy Flavor Averaging Group (HFLAV), while commenting on the effect of outliers on the fits. After removing the outliers and creating a comparable group of data-sets, we mention a few scenarios in the extraction of |Vub|. In all those scenarios, the extracted values of |Vub| are higher than that obtained by HFLAV. Our best results for |Vub|exc. are (3.94 ± 0.14) × 10−3 and $$ \left({3.93}_{-0.15}^{+0.14}\right) $$ 3.93 − 0.15 + 0.14 × 10−3 in frequentist and Bayesian approaches, respectively, which are consistent with that extracted from inclusive decays |Vub|inc. within 1 σ confidence interval.
Intra venous drug users (IVDUs) are at high risk for hepatitis C virus (HCV) infection owing to t... more Intra venous drug users (IVDUs) are at high risk for hepatitis C virus (HCV) infection owing to their high rate of drug abuses. The northeastern part of India has a high prevalence of IVDUs with Manipur being the worst hit state. The aim of the study was to document the molecular epidemiology, the patterns of HCV transmission, genomic variation and recombination events within HCV genome among IVDUs of Manipur, India. 91 anti-HCV sero-reactive blood samples were collected from IVDUs in Manipur. The samples were processed for RNA extraction, nested RT-PCR, sequencing and quantitative viral RNA estimation. Phylogeographic analysis of the sequenced core and NS5B regions of HCV genome was performed to determine the probable transmission route and recombinant HCV strains. 83 out of 91 anti-HCV seropositive samples were RNA positive (91.20%) based on 5 0 UTR of HCV genome by nested RT-PCR. Of the RNA positive samples, 73 paired partial core and NS5B gene were sequenced. Three major genotype and eight subtypes were detected while no recombinant strains were found. Individuals with genotype 1 had the mean viral load (5.94 ± 0.705 log 10 IU/ml) followed by genotype 3 (4.91 ± 0.49 log 10 IU/ml) and 6 (3.96 ± 0.32 log 10 IU/ml). The viral load was statistically significant among the male individuals at 4.822 ± 1.36 log 10 IU/ml compared to 4.767 ± 0.49 log 10 IU/ml for females (t = 3.249, p < 0.005). The phylogeographic results indicated 3b, 6h originated from Vietnam, 1a had Indian origin, 3a, 6k originated from southern China while 1b originated from Myanmar, respectively. The incidence of eight different subtypes in Manipur reflects the transmission of these strains from the ''Golden Triangle'' drug trafficking regions. Sequence analysis confirmed the transmission routes of HCV, which is linked to China and Vietnam for the newly emergent genotype 6 in northeastern India.
This article analyses the available inputs in B → πℓνℓ and B → ρℓνℓ decays which include the meas... more This article analyses the available inputs in B → πℓνℓ and B → ρℓνℓ decays which include the measured values of differential rate in different q2-bins (lepton invariant mass spectrum), lattice, and the newly available inputs on the relevant form-factors from the light-cone sum rules (LCSR) approach. We define different fit scenarios, and in each of these scenarios, we predict a few observables in the standard model (SM). For example, $$ R(M)=\frac{\mathcal{B}\left(B\to M{\ell}_i{\nu}_{\ell_i}\right)}{\mathcal{B}\left(B\to M{\ell}_j{\nu}_{\ell_j}\right)},{R}_{\ell_j}^{\ell_i}(M)=\frac{\mathcal{B}\left(B\to {\ell}_i{\nu}_{\ell_i}\right)}{\mathcal{B}\left(B\to M{\ell}_j{\nu}_{\ell_j}\right)} $$ R M = B B → M ℓ i ν ℓ i B B → M ℓ j ν ℓ j , R ℓ j ℓ i M = B B → ℓ i ν ℓ i B B → M ℓ j ν ℓ j with M = π or ρ and ℓi,j = e, μ or τ. We also discuss the new physics (NP) sensitivities of all these observables and obtain bounds on a few NP Wilson coefficients in b → uτντ decays using the available d...
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