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Ajay Kumar Rai

Publications and source records attributed to Ajay Kumar Rai.

At least 55 records · Page 3Linked to original sources

Mass-spectra of singly, doubly, and triply bottom baryons

The present work has been done on the baryons containing one, two, or three bottom quarks. In this article, the ground-state masses of $Ω_{b}^{-}$, $Ξ_{bb}^{0}$, $Ξ_{bb}^{-}$, $Ω_{bb}^{-}$, and $Ω_{bbb}^{*-}$ baryons are calculated within the framework of Regge phenomenology. Further, the values of Regge slopes and Regge intercepts for singly, doubly, and triply bottom baryons are estimated in both the ($J,M^{2}$) and ($n,M^{2}$) planes to calculate the excited-state masses of these baryons. Here our attempt is to assign a possible spin-parity to recently observed some singly bottom baryons and our results could provide useful information for future experimental searches. Our calculated masses are in agreement with the experimental observations where available and close to other theoretical predictions.

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Mass-Spectroscopy of [$bb][\bar{b}\bar{b}$] and [$bq][\bar{b}\bar{q}$] tetraquark states in a diquark-antidiquark formalism

In this article, we utilise the non-relativistic potential model to calculate the mass-spectra of all bottom [$bb][\bar{b}\bar{b}$] and heavy-light bottom [$bq][\bar{b}\bar{q}$] (q=u,d) tetraquark states in diquark-antidiquark approximation. The four-body problem is reduced into two-body problems by numerically solving the $Schr\ddot{o}dinger$ equation using a cornell-inspired potential along with relativistic correction term. The splitting structure of the tetraquark spectrum is described using spin-dependent terms (spin-spin, spin-orbit, and tensor). We have successfully calculated and predicted the masses of bottom mesons, diquarks and tetraquarks. The masses of S and P-wave tetraquark states [$bb][\bar{b}\bar{b}$] and [$bq][\bar{b}\bar{q}$], respectively, are found to be between 18.7-19.4 GeV and 10.4-11.3 GeV, in which the masses of S-wave [$bb][\bar{b}\bar{b}$] states are less than the 2$η_{b}$, $η_{b}Υ$, and 2$Υ$ threshold. Additionally, we investigated the $Z_b(10610)$ and $Z_ b(10650)$ states in the current model and found that they are 150 MeV below the $BB^{*}$ and $B^{*}B^{*}$ thresholds.

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Spectra and decay properties of $Λ_b$ and $Σ_b$ baryons

In this article, we study the radial states as well as orbital states mass spectra of the nonstrange baryons from bottom family utilizing hypercentral Constituent Quark Model(hCQM), a non-relativistic approach by employing screened potential as confining potential with color Coulomb potential. The spin-spin, spin-orbital and tensor interaction are considered for hyperfine splitting calculation. The mass spectra calculated and compared with other theoretical approaches. The Regge trajectories has been plotted in $(J, M^2)$ plane using the calculated mass spectra. Further, the single-pion decay and radiative decay have been described and magnetic moments are determined for the ground state.

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Identifying $D_{sJ}^*(2860)$ as a four resonance states through strong decay analysis

Experimentally observed excited strange charmed mesons $D_{s0}^*(2317)^{\pm}$, $D_{s1}(2460)^{\pm}$, $D_{s1}(2536)^{\pm}$, $D_{s2}^*(2573)^{\pm}$, $D_{s1}^*(2700)^{\pm}$, $D_{s1}^*(2860)^{\pm}$, $D_{s3}^*(2860)^{\pm}$, and $D_{sJ}(3040)^{\pm}$ are identified tentatively according to their spin, parity, and masses. Using the heavy quark effective theory in the leading order approximation, we study their strong decays to ground state charmed mesons plus light pseudoscalar mesons. The branching ratios are classified, $(D_{s0}^*(2317), D_{s1}(2460))$ as $(1^3P_0, 1P_1)$ and $(D_{s1}(2536), D_{s2}^*(2573))$ as $(1P_1^{\prime}, 1^3P_2)$, in heavy quark doublets. The $D_{s1}^*(2700)$ as $2^3S_1$ and its spin partner, $2^1S_0$ is still missing in the experiment. Its strong decay behavior is predicted. The assignment of $D_{sJ}^*(2860)$ as four resonance states $D_{s1}^*(2860)$, $D_{s2}^*(2860)$, $D_{s2}^{*\prime}(2860)$, $D_{s3}^*(2860)$ is favored, where for $D_{s3}^*(2860)^{\pm}$ the mass should be expected to higher than 2.86 GeV. The $D_{sJ}(3040)$ is more likely to be 2$P_1$ state. We construct the Regge trajectories of experimentally observed strange charmed mesons in $(M^2, J)$ and $(M^2, n_r)$ planes, which estimate the masses of $1^3D_3$, $1^3F_4$, $1D_2$, $1^1F_3$, $1D_2^{\prime}$, $1F_3^{\prime}$, $3^3S_1$, and $3P_1$ states with fixing the slopes and intercepts of the Regge lines. Moreover, the strong decay rates and the branching ratios of these higher excited states are also examined, which distinguished the dominant decay channels for these higher excited states. Our results could provide some important clues in LHCb, BESIII, KEK-B, and the forthcoming Belle II and $\overline{\mbox{\sffamily P}}${\sffamily ANDA} experiments.

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Ground and Excited state masses of $Ω_c^0$, $Ω_{cc}^+$ and $Ω_{ccc}^{++}$ baryons

The masses of ground and excited states of $Ω_c^0$, $Ω_{cc}^+$ and $Ω_{ccc}^{++}$ baryons are calculated within the framework of Regge phenomenology. Here our attempt is to assign a possible spin-parity to these obtained masses. Our calculated masses in $(J,M^2)$ plane with both natural ($J^{P}$ = $1/2^{+}$, $3/2^{-}$, $5/2^{+}$, ....) and unnatural ($J^{P}$ = $3/2^{+}$, $5/2^{-}$, $7/2^{+}$, ....) spin-parities are in agreement with the experimental observations where available and reasonably close to other theoretical predictions. Further we fix the slope and intercept of each Regge line in $(n, M^2)$ plane and estimate the masses of higher excited states of these baryons. The obtained mass relations and the mass value predictions could provide an useful information in future experimental searches and the spin-parity assignment of these states.

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Spectroscopic Investigation of Light Strange S=-1 $Λ$, $Σ$ and S=-2 $Ξ$ Baryons

The present study is dedicated to light-strange $Λ$ with strangeness S=-1, isospin I=0; $Σ$ with S=-1, I=1 and $Ξ$ baryon with S=-2 and $I=\frac{1}{2}$. In this article, hypercentral Constituent Quark Model with linear confining potential has been employed along with first order correction term to obtain the resonance masses for nearly upto 4 GeV. The calculated states include 1S-5S, 1P-4P, 1D-3D, 1F-2F and 1G (in few case) along with all the possible spin-parity assignments. Regge Trajectories have been explored for the linearly of the calculated masses for $(n,M^{2})$ and $(J,M^{2})$ respectively. Magnetic moments have been intensively studied for ground state spin $\frac{1}{2}$ and $\frac{3}{2}$, in addition to the configuration mixing for first negative parity state for $Ξ$. Lastly, transition magnetic moment and radiative decay width have been presented.

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Spectroscopic properties of $Δ$ Baryons

The resonance state of $Δ$ baryon existing in four isospin ($I=\frac{3}{2}$) states, has been studied using Hypercentral Constituent Quark Model (hCQM) with a simple linear potential with added first order correction. The calculated data range for 1S-5S, 1P-5P, 1D-4D and 1F-2F with possible spin-parity assignments of all the states. The magnetic moments have also been obtained for all four configuration. The $Nπ$ decay channel width has been calculated for few states. The linear nature of the data has been verified through Regge trajectories.

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Bottomonium spectroscopy motivated by general features of pNRQCD

The bottomonium mass spectra is computed in the framework of potential non-relativistic quantum chromodynamics. The potential consists of a static term incorporating Coulombic plus confinement part along with a correction term added non-perturbatively from pNRQCD, which is classified in powers of the inverse of heavy quark mass \textit{O}$(1/m)$. The masses of excited bottomonia are calculated by perturbatively adding spin-hyperfine, spin-orbit and tensor components of one gluon exchange interactions in powers of \textit{O}$(1/m^2)$. Calculated masses are found to be consistent with other theoretical studies and experimental data. The Regge trajectories of the calculated mass spectra are also constructed. The values of the wave-functions are extracted and employed to calculate the electromagnetic transition widths and $γγ$, $e^+e^-$, light hadron and $γγγ$ decay widths of several states at various leading orders, within the non-relativistic QCD formalism. Some of the experimentally reported states of bottomonium family like $Υ$(10860), $Υ$(11020) and X(10610) are identified as mixed $S-D$ wave and $P$-wave states.

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Spectrum of nonstrange singly charmed baryons in the constituent quark model

We study the masses of radial and orbital excited states of nonstrange singly charmed baryons in the framework of hypercentral Constituent Quark Model (hCQM). To obtain the mass spectra, the Coulomb plus screened potential is employed with the first order correction, which gives a relativistic effect of order $\cal{O}$$(1/m)$. The spin-spin, spin-orbit and tensor interactions are included (perturbatively as a spin dependent potential) in order to generate the splitting in mass spectra. We compare our computed mass spectra of nonstrange singly charmed baryons with the other theoretical predictions as well as with the experimental observations. We construct the Regge trajectories of these baryons in the $(J, M^2)$ plane. Further, we analyze the strong one pion decay rates for $S$, $P$ and the $D$-wave transitions in the framework of Heavy Hadron Chiral Perturbation Theory (HHChPT). Moreover, the electromagnetic properties like magnetic moments, transition magnetic moments and the radiative decay widths are determined for the ground state of these baryons in the constituent quark model.

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Strong decays analysis of excited nonstrange charmed mesons: Implications for spectroscopy

The strong decays of $D_1(2420)^0$, $D_2^*(2460)^0$, $D_2^*(2460)^+$, $D_2^*(2460)^-$, $D(2550)^0$, $D_J^*(2600)^0$, $D(2740)^0$, $D_3^*(2750)^0$, $D_3^*(2750)^+$, $D_3^*(2750)^-$, $D_J(3000)^0$, $D{_{J}^*}(3000)^0$ and $D_2^*(3000)^0$ resonance states are analyzed in the heavy quark mass limit of Heavy Quark Effective Theory (HQET). The individual decay rates and the branching ratios among the strong decays determine their spin and parity. From such states the Regge trajectories are constructed in $(J, M^2)$ and $(n_r, M^2)$ planes and further predict the masses of higher excited states (1$^1D_2$, 1$^3D_3$, 3$^1S_0$, 3$^3S_1$, 1$^1F_3$, 1$^3F_4$, 2$^3D_3$, 3$^3P_2$ and 2$^3F_4$) lying on Regge lines by fixing their slopes and intercepts. Moreover, the strong decay rates and the branching ratios of these higher excited states are also examined, which can help the experimentalists to search these states into their respective decay modes.

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Spectrum of strange singly charmed baryons in the constituent quark model

Excited states masses of the strange singly charmed baryons are calculated using the non-relativistic approach of hypercentral Constituent Quark Model (hCQM). The hyper-Coulomb plus screened potential is used as a confinement potential with the first order correction. The spin-spin, spin-orbit and spin-tensor interaction terms are included perturbatively. Our calculated masses are allowed to construct the Regge trajectories in both $(n_r, M^2)$ and $(J, M^2)$ planes. The mass spectra and the Regge trajectories study predict the spin-parity of $Ξ{_c(2970)^{+/0}}$, $Ξ{_c(3080)^{+/0}}$, $Ξ{_c(3123)^+}$, $Ω{_c}(3000)^0$ and $Ω{_c}(3119)^0$ baryons. Moreover, the strong one pion decay rates of the isodoublet states of $Ξ{_c(2645)}$, $Ξ{_c(2790)}$ and $Ξ{_c(2815)}$ are analyzed in the framework of Heavy Hadron Chiral Perturbation Theory (HHChPT). Also, the ground state magnetic moments and the radiative decay rates based on the transition magnetic moments are calculated in the framework of constituent quark model.

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Charmonium spectroscopy motivated by general features of pNRQCD

Mass spectrum of charmonium is computed in the framework of potential non-relativistic quantum chromodynamics. \textit{O}$(1/m)$ and \textit{O}$(1/m^2)$ relativistic corrections to the Cornell potential and spin-dependent potential have been added, and is solved numerically. New experimentally observed and modified positive and negative parity states like ${{\boldsymbol ψ}{(4230)}}$, ${{\boldsymbol ψ}{(4260)}}$, ${{\boldsymbol ψ}{(4360)}}$, ${{\boldsymbol ψ}{(4390)}}$, ${{\boldsymbol ψ}{(4660)}}$, ${{\boldsymbol χ}_{c1}{(4140)}}$ and ${{\boldsymbol χ}_{c1}{(4274)}}$ near open-flavor threshold have also been studied. We explain them as admixtures of S-D wave states and P-wave states. Apart from these states, some other states like ${{\mathit X}{(3915)}}$, ${{\boldsymbol χ}_{c1}{(3872)}}$, ${{\boldsymbol ψ}{(3770)}}$ and ${{\boldsymbol ψ}{(4160)}}$ have been identified as $2^3P_0$, $2^3P_1$, $1^3D_1$ and $2^3D_1$ states. Subsequently, the electromagnetic transition widths and $γγ$, $e^+e^-$, light hadron and $γγγ$ decay widths of several states are calculated at various leading orders. All the calculated results are compared with experimental and results from various theoretical models.

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Spectroscopy of light $N^{*}$ baryons

We present the masses of N baryon upto 3300 MeV. The radial and orbital excited states are determined using hypercentral constituent quark model with first order correction. The obtained masses are compared with experimental results and other theoretical prediction. The Regge Trajectories are also determined in (n, $M^2$) and (J, $M^2$) planes. Moreover, the magnetic moments for $J^{P}= \frac{1}{2}^{+}, \frac{1}{2}^{-}$ are calculated. We also calculate the $Nπ$ decay width of excited nucleons.

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Decay properties of singly charmed baryons

The magnetic moments, transition magnetic moments and the radiative decay widths of singly charmed baryons are calculated with $ {J^P = \frac{1}{2}}^+$ and $ {J^P = \frac{3}{2}}^+$ in the constitute quark model. Further, the strong decay rates for $ S $, $ P $ and $ D $ wave transitions are also presented. The singly charmed baryon masses used in the calculations were obtained from the hypercentral Constitute Quark Model (hCQM) without and with first order relativistic correction. Obtained results are compared with experimental observation as well as with the other theoretical predictions.

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Interaction and Identification of the Meson-Baryon molecules

The challenges with the molecular model of the multiquark systems are the identification of the hadronic molecules and the interaction between two color neutral hadrons. We study the di-hadronic molecular systems with proposed interaction potential as s-wave one boson exchange potential along with Screen Yukawa-like potential, and arrived with the proposal that within hadronic molecule the two color neutral hadrons experience the dipole-like interaction. The present study is the continuation of our previous study \cite{arxiv-Rathaud-penta}. With the proposed interaction potential, the mass spectra of $Σ_{s}K^{*}$, $Σ_{c}K^{*}$, $Σ_{b}K^{*}$, $Σ_{s}D^{*}$, $Σ_{c}D^{*}$, $Σ_{b}D^{*}$, $Σ_{s}B^{*}$, $Σ_{c}B^{*}$, $Σ_{b}B^{*}$, $Ξ_{s}K^{*}$, $Ξ_{c}K^{*}$, $Ξ_{b}K^{*}$, $Ξ_{s}D^{*}$, $Ξ_{c}D^{*}$, $Ξ_{b}D^{*}$, $Ξ_{s}B^{*}$, $Ξ_{c}B^{*}$, $Ξ_{b}B^{*}$ meson-baryon molecules are predicted. The Weinberg compositeness theorem which provides clue for the compositeness of the state is used for determination of the scattering length and effective range. The present study predict $P_{c}(4450)$ pentaquark sate as $Σ_{c}D^{*}$ molecule with $I(J^{P})=\frac{1}{2}(\frac{3}{2}^{-})$. The formalism also predicts some very interesting open as well as hidden flavour near threshold molecular pentaquark states.

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Interaction and Identification of the Doubly Heavy Di-Hadronic Molecules

We study the interesting problem of interaction and identification of the hadronic molecules which seem to be deuteron-like structure. In particular, we propose a binding mechanism in which One Boson Exchange Potential plus Yukawa screen-like potential is applied in their relative s-wave state. We propose the dipole-like interaction between two color neutral states to form a hadronic molecule. For the identification of the hadronic molecules, the Weinberg's compositeness theorem is used to distinguish the molecule from confined (elementary) state. The present formalism predict some di-hadronic molecular states, involving quarks (s, c, b or $\overline{s}$, $\overline{c}$, $\overline{b}$) as a constituents, namely, $pn$, $K\overline{K}$, $ρ\overlineρ$, $K^{*}\overline{K^{*}}$, $D\overline{D^{*}}$($\overline{D}D^{*}$), $D^{*}\overline{D^{*}}$, $B\overline{B^{*}}$, $B^{*}\overline{B^{*}}$, $D^{*\pm}\overline{D_{1}^{0}}$, $ D^{0}\overline{K^{\pm}}$, $D^{*0}\overline{K^{\pm}}$, with their possible quantum numbers.

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Spectroscopy and Decay properties of the charmonium

The mass spectra of charmonium are investigated using a Coulomb plus linear (Cornell) potential. Gaussian wave function in position space as well as in momentum space are employed to calculate the expectation value of potential and kinetic energy respectively. Various experimental states ($X(4660)(5^{3}S_{1})$, $X(3872)(2^{3}P_{1})$, $X(3900)(2^{1}P_{1})$, $X(3915)(2^{3}P_{0})$ and $X(4274)(3^{3}P_{1})$ etc.) are assigned as charmonium states. We also study the Regge trajectories, pseudoscalar and vector decay constants, the Electric and Magnetic dipole transition rates and the annihilation decay width for charmonium states.

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Spectroscopy of $Ω_{ccb}$ baryon in Hypercentral Quark Model

We extract the mass spectra of triply heavy baryon $Ω_{ccb}$ using Hypercentral constituent quark model. The first order correction is also added to the potential term of Hamiltonian. The radial and orbital excited state masses are also determined. Moreover, the Regge trajectories and magnetic moments are also given for this baryon.

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