showing 17 related works from this author
Physical observables in the decay Λb→Λc(→Λ+π)+τ−+ν̄τ
2015
We analyze the tauonic semileptonic baryon decays [Formula: see text] with particular emphasis on the lepton helicity flip contributions which vanish for zero lepton masses. We calculate the total rate, differential decay distributions, the longitudinal and transverse polarization components of the [Formula: see text] and the [Formula: see text], and the lepton-side forward-backward asymmetries. We use the covariant confined quark model to provide numerical results on these observables.
Semileptonic decays of theBcmeson
2001
We study the semileptonic transitions ${B}_{c}\ensuremath{\rightarrow}{\ensuremath{\eta}}_{c},$ $J/\ensuremath{\psi},$ D, ${D}^{*},$ B, ${B}^{*},$ ${B}_{s},$ ${B}_{s}^{*}$ in the framework of a relativistic constituent quark model. We use experimental data on leptonic $J/\ensuremath{\psi}$ decay, lattice and QCD sum rule results on leptonic ${B}_{c}$ decay, and experimental data on radiative ${\ensuremath{\eta}}_{c}$ transitions to adjust the quark model parameters. We compute all form factors of the above semileptonic ${B}_{c}$ transitions and give predictions for various semileptonic ${B}_{c}$ decay modes including their $\ensuremath{\tau}$ modes when they are kinematically accessible. Th…
J/ψ dissociation cross sections in a relativistic quark model
2003
We calculate the amplitudes and the cross sections of the charm dissociation processes J/\psi \pi => D \bar D, D* \bar D, D \bar D*, D* \bar D* within a relativistic constituent quark model. We consistently account for the contributions coming from both the box and triangle diagrams that contribute to the dissociation processes. The cross section is dominated by the D* \bar D and D* \bar D* channels. When summing up the four channels we find a maximum total cross section of about 2.3 mb at sqrt(s) \approx 4.1 GeV. We compare our results to the results of other model calculations.
Semileptonic decaysΛc+→Λℓ+νℓ(ℓ=e,μ)in the covariant quark model and comparison with the new absolute branching fraction measurements of Belle and BES…
2016
We present precise theoretical predictions for the absolute branching fractions of ${\mathrm{\ensuremath{\Lambda}}}_{c}^{+}\ensuremath{\rightarrow}\mathrm{\ensuremath{\Lambda}}{\ensuremath{\ell}}^{+}{\ensuremath{\nu}}_{\ensuremath{\ell}}(\ensuremath{\ell}=e,\ensuremath{\mu})$ decays in the covariant confined quark model. This study is motivated by two recent and accurate measurements of the absolute branching fractions of ${\mathrm{\ensuremath{\Lambda}}}_{c}^{+}\ensuremath{\rightarrow}p{K}^{\ensuremath{-}}{\ensuremath{\pi}}^{+}$ and ${\mathrm{\ensuremath{\Lambda}}}_{c}^{+}\ensuremath{\rightarrow}\mathrm{\ensuremath{\Lambda}}{e}^{+}{\ensuremath{\nu}}_{e}$ by the Belle Collaboration at the KE…
Semileptonic decays ofBcmesons into charmonium states in a relativistic quark model
2005
We use the framework of a relativistic constituent quark model to study the semileptonic transitions of the ${B}_{c}$ meson into $(\overline{c}c)$ charmonium states where $(\overline{c}c)={\ensuremath{\eta}}_{c}(^{1}S_{0})$, $J/\ensuremath{\psi}(^{3}S_{1})$, ${\ensuremath{\chi}}_{c0}(^{3}P_{0})$, ${\ensuremath{\chi}}_{c1}(^{3}P_{1})$, ${h}_{c}(^{1}P_{1})$, ${\ensuremath{\chi}}_{c2}(^{3}P_{2})$, $\ensuremath{\psi}(^{3}D_{2})$. We compute the ${q}^{2}$ dependence of all relevant form factors and give predictions for their semileptonic ${B}_{c}$ decay modes including also their $\ensuremath{\tau}$ modes. We derive a formula for the polar angle distribution of the charged lepton in the $(l{\ens…
Heavy-to-light semileptonic decays ofΛbandΛcbaryons in the covariant confined quark model
2014
We present a detailed analysis of the heavy-to-light semileptonic decays of theb andc baryons �b → pl ¯ νl andc → nl + νl in the covariant confined quark model. We calculate the invariant and helicity amplitudes of the two processes which are then used to analyze their angular decay distributions, their rates and asymmetry parameters.
Rare baryon decaysΛb→Λℓ+ℓ−(ℓ=e,μ,τ) andΛb→Λγ: Differential and total rates, lepton- and hadron-side forward-backward asymmetries
2013
Using the covariant constituent quark model previously developed by us, we calculate the differential rate and the forward-backward asymmetries on the lepton and hadron side for the rare baryon decays ${\ensuremath{\Lambda}}_{b}\ensuremath{\rightarrow}\ensuremath{\Lambda}{\ensuremath{\ell}}^{+}{\ensuremath{\ell}}^{\ensuremath{-}}$ ($\ensuremath{\ell}=e$, $\ensuremath{\mu}$, $\ensuremath{\tau}$) and ${\ensuremath{\Lambda}}_{b}\ensuremath{\rightarrow}\ensuremath{\Lambda}\ensuremath{\gamma}$. We use helicity methods to write down a threefold joint angular decay distribution for the cascade decay ${\ensuremath{\Lambda}}_{b}\ensuremath{\rightarrow}\ensuremath{\Lambda}(\ensuremath{\rightarrow}p{\…
Semileptonic D(s) -meson decays in the light of recent data
2018
Inspired by recent improved measurements of charm semileptonic decays at BESIII, we study a large set of $D({D}_{s})$-meson semileptonic decays where the hadron in the final state is one of ${D}^{0}$, $\ensuremath{\rho}$, $\ensuremath{\omega}$, ${\ensuremath{\eta}}^{(\ensuremath{'})}$ in the case of ${D}^{+}$ decays, and ${D}^{0}$, $\ensuremath{\phi}$, ${K}^{0}$, ${K}^{*}(892{)}^{0}$, ${\ensuremath{\eta}}^{(\ensuremath{'})}$ in the case of ${D}_{s}^{+}$ decays. The required hadronic form factors are computed in the full kinematical range of momentum transfer by employing the covariant confined quark model developed by us. A detailed comparison of the form factors with those from other appro…
Form factors for semileptonic, nonleptonic, and rareB(Bs)meson decays
2012
We provide new values for the model parameters of the covariant constituent quark model (with built–in infrared confinement) in the meson sector by a fit to the leptonic decay constants and a number of electromagnetic decays. We then evaluate, in a parameter-free way, the form factors of the B(Bs) ! P(V ) transitions in the full kinematical region of momentum transfer. As an application of our results we calculate the widths of the nonleptonic Bs-decays into Ds D + , D � s D + s +D s D � + s
Semileptonic and nonleptonic decays of B c
2007
Using our relativistic constituent quark model we present results on the exclusive nonleptonic and semileptonic decays of the B c-meson. The nonleptonic decays are studied in the framework of the factorization approximation. We calculate the branching ratios for a large set of exclusive nonleptonic and semileptonic decays of the B c meson and compare our results with the results of other models.
Exclusive semileptonic and nonleptonic decays of the Bc meson
2006
We study exclusive nonleptonic and semileptonic decays of the Bc-meson within a relativistic constituent quark model previously developed by us. For the nonleptonic decays we use the factorizing approximation. We update our model parameters by using new experimental data for the mass and the lifetime of the Bc meson and the leptonic decay constants of the D-meson. We calculate the branching ratios for a large set of exclusive nonleptonic and semileptonic decays of the $B_c$ meson and compare our results with the results of other studies. As a guide for further experimental exploration we provide explicit formulas for the full angular decay distributions in the cascade decays Bc^- => J/ps…
Analyzing lepton flavor universality in the decays Λb→Λc(*)(12±,32−)+ℓν¯ℓ
2018
Lepton flavor universality can be tested in the semileptonic decays Λb→Λc(*), where Λc(*) denotes either the ground state Λc(2286) (with JP=1/2+) or its orbital excitations Λc(2595) (with JP=1/2−) and Λc(2625) (with JP=3/2−). We calculate the differential decay rates as well as the branching fractions of these decays for both tauonic and muonic modes with form factors obtained from a covariant confined quark model previously developed by us. We present results for the rate ratios of the tauonic and muonic modes which provide important tests of lepton flavor universality in forthcoming experiments.
Polarization effects in the cascade decayΛb→Λ(→pπ−)+J/ψ(→ℓ+ℓ−)in the covariant confined quark model
2013
We calculate the invariant and helicity amplitudes for the nonleptonic decay ${\ensuremath{\Lambda}}_{b}\ensuremath{\rightarrow}\ensuremath{\Lambda}+J/\ensuremath{\psi}$, $\ensuremath{\psi}(2S)$ in the covariant confined quark model. We discuss joint angular decay distributions in the cascade decay ${\ensuremath{\Lambda}}_{b}\ensuremath{\rightarrow}\ensuremath{\Lambda}(\ensuremath{\rightarrow}p{\ensuremath{\pi}}^{\ensuremath{-}})+J/\ensuremath{\psi}$, $\ensuremath{\psi}(2S)(\ensuremath{\rightarrow}{\ensuremath{\ell}}^{+}{\ensuremath{\ell}}^{\ensuremath{-}})$ and calculate some of the asymmetry parameters that characterize the joint angular decay distribution. We confirm expectations from th…
One-photon decay of the tetraquark stateX(3872)→γ+J/ψin a relativistic constituent quark model with infrared confinement
2011
We further explore the consequences of treating the $X(3872)$ meson as a tetraquark bound state by analyzing its one-photon decay $X\ensuremath{\rightarrow}\ensuremath{\gamma}+J/\ensuremath{\psi}$ in the framework of our approach developed in previous papers which incorporates quark confinement in an effective way. To introduce electromagnetism we gauge a nonlocal effective Lagrangian describing the interaction of the $X(3872)$ meson with its four constituent quarks by using the $P$-exponential path-independent formalism. We calculate the matrix element of the transition $X\ensuremath{\rightarrow}\ensuremath{\gamma}+J/\ensuremath{\psi}$ and prove its gauge invariance. We evaluate the $X\ens…
Theoretical description of the decays Λb→Λ(*)(12±,32±)+J/ψ
2017
We calculate the invariant and helicity amplitudes for the transitions ${\mathrm{\ensuremath{\Lambda}}}_{b}\ensuremath{\rightarrow}{\mathrm{\ensuremath{\Lambda}}}^{(*)}({J}^{P})+J/\ensuremath{\psi}$, where the ${\mathrm{\ensuremath{\Lambda}}}^{(*)}({J}^{P})$ are $\mathrm{\ensuremath{\Lambda}}(sud)$-type ground and excited states with ${J}^{P}$ quantum numbers ${J}^{P}={\frac{1}{2}}^{\ifmmode\pm\else\textpm\fi{}}$, ${\frac{3}{2}}^{\ifmmode\pm\else\textpm\fi{}}$. The calculations are performed in the framework of a covariant confined quark model previously developed by us. We find that the values of the helicity amplitudes for the ${\mathrm{\ensuremath{\Lambda}}}^{*}(1520,{\frac{3}{2}}^{\ensu…
Light baryons and their electromagnetic interactions in the covariant constituent quark model
2012
We extend the confined covariant constituent quark model that was previously developed by us for mesons to the baryon sector. In our numerical calculation we use the same values for the constituent quark masses and the infrared cutoff as have been previously used in the meson sector. In a first application we describe the static properties of the proton and neutron, and the $\Lambda$-hyperon (magnetic moments and charge radii) and the behavior of the nucleon form factors at low momentum transfers. We discuss in some detail the conservation of gauge invariance of the electromagnetic transition matrix elements in the presence of a nonlocal coupling of the baryons to the three constituent quar…
Form-factor-independent test of lepton universality in semileptonic heavy meson and baryon decays
2021
In the semileptonic decays of heavy mesons and baryons the lepton-mass dependence factors out in the quadratic $\cos^2\theta$ coefficient of the differential $\cos\theta$ distribution. We call the corresponding normalized coefficient the convexity parameter. This observation opens the path to a test of lepton universality in semileptonic heavy meson and baryon decays that is independent of form-factor effects. By projecting out the quadratic rate coefficient, dividing out the lepton-mass-dependent factor and restricting the phase space integration to the $\tau$ lepton phase space, one can define optimized partial rates which, in the Standard Model, are the same for all three $(e,\mu,\tau)$ …