arXiv subjects

Vaishali Guleria

Publications and source records attributed to Vaishali Guleria.

5 recordsLinked to original sources

arXiv2024

Radiative $E1$ transitions between $^3P_1$ and $^3S_1$ quarkonium states

In this work we study the E1 decay processes, $^3P_1$ $\rightarrow$ $^3S_1γ$, and $^3S_1$ $\rightarrow$ $^3P_1γ$ in the framework of Bethe-Salpeter equation and calculate their decay widths. We have used algebraic forms of Salpeter wave functions obtained through analytic solutions of mass spectral equations for ground and excited states of $^3S_1$, and $^3P_1$ equal mass quarkonia in approximate harmonic oscillator basis to do analytic calculations of their decay widths. These decay widths have been compared with data and other models.

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arXiv2023

($γ$, $χ_{cJ}(J=0,1)$) and ($γ$, $η_c$) production in electron-positron annihilation at $\sqrt{s}=10.6$ GeV and $4.6$ GeV in the framework of Bethe-Salpeter equation

In present work we study the production of ground and excited charmonium states in $e^- e^+ \rightarrow γχ_{cJ}(nP)(J=0,1)$, and $e^- e^+ \rightarrow γη_c(nS)$, through leading order (LO) diagrams, which proceed through exchange of a virtual photon that couples to $γ$ and $η_c/χ_{cJ}$ through the triangular quark loop diagram, in the framework of $4\times 4$ Bethe-Salpeter equation (BSE), at center of mass energies $\sqrt{s}=10.6$ GeV(Belle energy), and 4.6 GeV (BESIII energy). The amplitude simplifies to a general form required by Lorentz-covariance, in terms of its form factors. The cross sections for these processes with leading order (tree level) diagrams alone at $\sqrt{s}$=10.6 GeV provide a sizable contribution, which might be mainly due to the BSE being a fully relativistic approach that incorporates the relativistic effect of quark spins and can also describe internal motion of constituent quarks within the hadron in a relativistically covariant manner. Our results are compared with recent Belle data at 10.6 GeV, and BESIII data at 4.6 GeV, as well as other models. Plots of cross sections versus the center-of mass energy, $\sqrt{s}$ reveal mild fluctuations in their behaviour for all the three processes in the low energy ($\sqrt{s}$ = 4 - 6 GeV) region, and are analyzed in terms of the form factors.

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arXiv2022

$J/Ψ$ and $χ_{cJ}(J=0,1)$ production in electron-positron annihilation at $\sqrt{s}=10.6$ GeV in the framework of Bethe-Salpeter equation

In present work we study the production of ground and excited charmonium pairs in $e^- e^+ \rightarrow Ψ(nS)+ χ_{cJ}(nP)$ for $J=0,1$ and $n=1,2$, through leading order (LO) tree-level diagrams $\sim O(α_{em} α_s)$, which proceed through exchange of a virtual photon and an internal gluon line connecting two quark lines (in the triangle quark loop part of the diagram), in the framework of $4\times 4$ Bethe-Salpeter equation, at center of mass energy, $\sqrt{s}=10.6 GeV.$ We have tried to show that the cross sections for this process calculated with use of the four leading order $\sim O(α_{em} α_s)$ diagrams using BSE approach come close to experimental data, which might be mainly due to the consistent treatment of motion of quarks inside the hadrons in the BSE framework.

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arXiv2021

$E1$ and M1 radiative transitions involving heavy-light axial, pseudoscalar and vector quarkonia in the framework of Bethe-Salpeter equation

This work is an extension of our previous work in \cite{bhatnagar20} to calculate M1 transitions, $0^{-+}\rightarrow 1^{--} γ$, and E1 transitions involving axial vector mesons such as, $1^{+-} \rightarrow 0^{-+}γ$, and $0^{-+}\rightarrow 1^{+-} γ$ for which very little data is available as of now. We make use of the general structure of the transition amplitude, $M_{fi}$ derived in our previous work \cite{bhatnagar20} as a linear superposition of terms involving all possible combinations of $++$, and $--$ components of Salpeter wave functions of final and initial hadrons. In the present work, we make use of leading Dirac structures in the hadronic Bethe-Salpeter wave functions of the involved hadrons, which makes the formulation more rigorous. We evaluate the decay widths for both the above mentioned $M1$ and $E1$ transitions. We have used algebraic forms of Salpeter wave functions obtained through analytic solutions of mass spectral equations for ground and excited states of $1^{--}$,$0^{-+}$ and $1^{+-}$ heavy-light quarkonia in approximate harmonic oscillator basis to do analytic calculations of their decay widths. We have compared our results with experimental data, where ever available, and other models.

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arXiv2021

Mass spectra and decay constants of heavy-light axial quarkonia in the framework of Bethe-Salpeter equation

In this work we calculate the mass spectrum and decay constants of ground and excited states of heavy-light $P$-wave mesons such as $1^{++}$ and $1^{+-}$, with quark composition, $c\overline{u}, c\overline{s}, b\overline{u}, b\overline{s}$, and $b\overline{c}$ in the framework of a QCD motivated Bethe-Salpeter equation (BSE) by making use of the exact treatment of the spin structure $(γ_μ\bigotimesγ_μ)$ in the interaction kernel, In this $4\times 4$ BSE framework, the coupled Salpeter equations for $Q\overline{q}$ are first solved for the confining part of interaction, and are shown to decouple under heavy-quark approximation. Then the one-gluon-exchange interaction is perturbatively incorporated, leading to their mass spectral equations. The analytic forms of wave functions obtained from these equations are then used for calculation of leptonic decay constants of ground and excited states of $1^{++}$, and $1^{+-}$ as a test of these wave functions and the over all framework.

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