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Ajay Kumar Rai

Publications and source records attributed to Ajay Kumar Rai.

At least 73 records · Page 4Linked to original sources

Dimesonic states with the heavy-light flavour mesons

In this work, we have calculated the mass spectra and decay properties of dimesonic states in the variational scheme. The inter-mesonic interaction considered as the Hellmann potential and One Pion Exchange potential. The mass spectra of the $D\overline{D^{*}}$, $D^{*}\overline{D^{*}}$, $D\overline{B^{*}}$, $B^{*}\overline{D}$, $B\overline{B^{*}}$, $B^{*}\overline{B^{*}}$ bound states are calculated. The states X(3872), $X_{2c}(4013)$, $Z_{b}(10610)/X_{b}$ and $Z_{b}(10650)/X_{b2}$ are compared with $D\overline{D^{*}}$, $D^{*}\overline{D^{*}}$, $B\overline{B^{*}}$ and $B^{*}\overline{B^{*}}$ dimesonic bound states. {\bf To probe the molecular structure of the compared states, we have calculated the decay properties sensitive to their long and short distance structure of the hadronic molecule. The radiative decay for the state X(3872) into $J/ψγ$ and $ψ(2S) γ$ have been calculated and the ratio is found to be ten times lesser than the experimental value whereas the other decay modes are comparable with other theoretical and experimental results. This results restrict us to assigned the pure molecular structure to the X(3872). But, Our results suggests that the compared states are close to the molecular structure or have dominant molecular component in their wave function. Apart from these, the other calculated mass spectra of dimesonic states are predicted and for such bound states, the experimental search are suggested.}

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Excited State Mass spectra and Regge trajectories of Bottom Baryons

We present the mass spectra of radial and orbital excited states of singly heavy bottom baryons; $Σ_{b}^{+}, Σ_{b}^-, Ξ_b^-, Ξ_b^0, Λ_b^0$ and $Ω_b^-$. The QCD motivated hypercentral quark model is employed for the three body description of baryons and the form of confinement potential is hyper coulomb plus linear. The first order correction to the confinement potential is also incorporated in this work. The semi-electronic decay of $Ω_b$ and $Ξ_b$ are calculated using the spectroscopic parameters of the baryons. The computed results are compared with other theoretical predictions as well as with the available experimental observations. The Regge trajectories are plotted in (n, $M^2$) plane.

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Excited state mass spectra, Decay properties and Regge trajectories of charm and charm-strange mesons

The framework of phenomenological quark-antiquark potential (Coulomb plus linear confinement) model with the Gaussian wave function is used for detailed study of masses of the ground, orbitally and radially excited states of heavy-light $Q\overline{q}$, $\left(Q=c,q=u/d,s\right)$ mesons. We incorporate $\mathcal{O}(1/m)$ correction to the potential energy term and relativistic corrections to the kinetic energy term of the hamiltonian. The spin-hyperfine, the spin-orbit and the tensor interactions incorporating the effect of mixing are employed to obtained the pseudoscalar, the vector, radially and orbitally excited states meson masses. The Regge trajectories in the $(J,M^{2})$ and $(n_r,M^{2})$ planes for heavy-light meson are investigated with their corresponding parameters. Leptonic and radiative leptonic decay widths and corresponding branching ratios are computed. The mixing parameters are also estimated in the present work. Our predictions are in good agreement with experimental results as well as lattice and other theoretical models.

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Excited state mass spectra of doubly heavy $Ξ$ baryons

In this paper, the mass spectra are obtained for doubly heavy $Ξ$ baryons, namely, $Ξ_{cc}^{+}$, $Ξ_{cc}^{++}$, $Ξ_{bb}^{-}$, $Ξ_{bb}^{0}$, $Ξ_{bc}^{0}$ and $Ξ_{bc}^{+}$. These baryons are consist of two heavy quarks($cc$, $bb$ and $bc$) with a light($d$ or $u$) quark. The ground, radial and orbital states are calculated in framework of Hypercentral constituent quark model with coul- omb plus linear potential. Our outcomes are also compared with other predictions, thus, the average possible range of excited states masses of these $Ξ$ baryons can be determined. The study of the Regge trajectories are performed in (n, $M^{2}$) and (J, $M^{2}$) planes and their slopes and intercepts are also determined. Lastly, the ground state magnetic moments of these doubly heavy baryons are also calculated.

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Mass spectra and Regge trajectories of $Λ_{c}^{+}$, $Σ_{c}^{0}$, $Ξ_{c}^{0}$ and $Ω_{c}^{0}$ Baryons

We calculate the mass spectra of the singly charmed baryons ($Λ_{c}^{+}$, $Σ_{c}^{0}$, $Ξ_{c}^{0}$ and $Ω_{c}^{0}$) using Hypercentral constituent quark model(hCQM). The hyper color coloumb plus linear potential is used to calculate the masses of positive(upto $J^{p}=\frac{7}{2}^{+}$) and negative parity(upto $J^{p}=\frac{9}{2}^{-}$) excited states. The spin-spin, spin-orbital and tensor interaction terms are also incorporated for mass spectra. We have compared our results with other theoretical predictions and Lattice QCD for each baryons. Moreover, the known experimental results are also reasonably closed to our predicted masses. By using the radial and orbital excitation, we construct Regge trajectories for the baryons in (n,$M^{2}$) plane and find their slopes and intercepts. The other properties like, magnetic moments, radiative transitions and radiative decay widths of these baryons are also calculated successfully.

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Excited State Mass spectra of doubly heavy baryons $Ω_{cc}$, $Ω_{bb}$ and $Ω_{bc}$

We discuss the mass spectrum of $Ω$ baryon with two heavy quarks and one light quark (\textit{ccs, bbs and bcs}). The main goal of the paper is to calculate the ground state masses and after that, the positive and negative parity excited states masses are also obtained within a Hypercentral Constituent quark model, using coulomb plus linear potential framework. We also added first order correction to the potential. The mass spectra upto 5S for radial excited states and 1P-5P, 1D-4D and 1F-2F states for orbital excited states are computed for $Ω_{cc}$, $Ω_{bb}$ and $Ω_{bc}$ baryons. Our obtained results are compared with other theoretical predictions which could be a useful complementary tool for the interpretation of experimentaly unknown heavy baryon spectra. The Regge trajectory is constructed in both ($n_r$, $M^{2}$) and ($J$, $M^{2}$) planes for $Ω_{cc}$,$Ω_{bb}$ and $Ω_{bc}$ baryons and their slopes and intercepts are also determined. Magnetic moments of doubly heavy $Ω'$s are also calculated.

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Excited State Mass spectra of Singly Charmed Baryons

Mass spectra of excited states of the singly charmed baryons are calculated using the hypercentral description of three body system. The baryon consist of a charm quark and light quarks (u, d and s) are studied in the framework of QCD motivated constituent quark model. The form of confinement potential is hyper coloumb plus power potential with potential index $ν$, varying from 0.5 to 2.0. The first order correction to the confinement potential is also incorporated in this approach. The radial as well as orbital excited state masses of $Σ_{c}^{++}, Σ_{c}^+, Σ_{c}^0, Ξ_c^+, Ξ_c^0, Λ_c^+, Ω_c^0$ baryons, are reported in this paper. We have incorporated spin-spin, spin-orbit and tensor interactions perturbatively in the present study. The semi-electronic decay of $Ω_c$ and $Ξ_c$ are also calculated using the spectroscopic parameters of these baryons. The computed results are compared with other theoretical predictions as well as with the available experimental observations. We also construct the Regge trajectory in ($n_r$, $M^{2}$) and (J, $M^{2}$) plane for these baryons.

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The mass spectra and decay properties of dimesonic states, using the Hellmann potential

Mass spectra of the dimesonic (meson-antimeson) molecular states are computed using the Hellmann potential in variational approach, which consists of relativistic correction to kinetic energy term as well as to the potential energy term. For the study of molecular bound state system, the Hellmann potential of the form $V(r)=-\frac{α_{s}}{r} + \frac{B e^{-Cr}}{r}$ is being used. The one pion exchange potential (OPEP) is also incorporated in the mass calculation. The digamma decay width and decay width of the dimesonic system are evaluated using the wave function. The experimental states such as $f_{0}(980)$, $b_{1}(1235)$, $h_{1}(1380)$, $a_{0}(1450)$, $f_{0}(1500)$, $f_{2}'(1525)$,$f_{2}(1565)$, $h_{1}(1595)$, $a_{2}(1700)$, $f_{0}(1710)$, $f_{2}(1810)$ are compared with dimesonic states. Many of these states (masses and their decay properties) are close to our theoretical predictions.

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Mixing and lifetime of B-meson using Coulomb plus power potential

The investigation of mixing phenomena and lifetime in neutral B meson systems provides an important testing ground for standard model flavour dynamics. Spectroscopic parameters has been used to calculate the pseudoscalar decay constant and predictions of mixing mass parameters and lifetimes of the B$_{d}$ and B$_{s}$ mesons.

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Properties of $Q\bar Q$ mesons in non-relativistic QCD formalism

The decay rates of $Q \bar Q$ mesons ($Q \varepsilon {c, b}$) are studied in the NRQCD formalism in terms of their short distance and long distance coefficients. The long distance coefficients are obtained through phenomenological potential model description of the mesons. The model parameters that reproduces the mass spectrum of the $c \bar c$, $b \bar b$ and $c \bar b$ mesons are employed to study the decay widths of these mesons. We extract the mass spectrum as well as the reproduces the respective radial wave functions from the different potential models as well as from non-relativistic phenomenological quark antiquark potential of the type $V(r)=-\frac{α_c}{r}+A r^ν$, with $ν$ varying from 0.5 to 2. The spin hyperfine and spin-orbit interactions are employed to obtain the masses of the pseudoscalar and vector mesons. The decay constants with QCD corrections are computed in this model as well as in the case of other potential models for comparison. The digamma and dileptonic decays of $c \bar c$, and $b \bar b$ mesons are investigated using some of the known potential models without and with radiative corrections up to the lowest order. These decay width are also computed within the NRQCD formalism up to $O(v^4)$ by making uses of the respective spectroscopic parameters of the models. Our theoretical predictions of the decays of the $c \bar c$, and $b \bar b$ mesons and the results obtained from some of the other potential schemes are compared with the experimental values. The partial widths and life time of the $B_c$ meson are also computed using the model parameters and are found to be in good accordance with the experimental values.

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Properties of doubly charmed baryons in the quark-diquark model

Baryons containing two heavy quarks are important and interesting systems to study the quark-diquark structure of baryons and to understand the dynamics of QCD at hadronic scale. The Selex Collaboration has recently reported the discovery of $Ξ_{cc}$ with a mass of 3.519 Ge$V$. However, other groups such as Babar, Belle and Focus have all failed to confirm this state. So there is a demand to review this state both theoretically and experimentally. We report here the spectra and magnetic moments of $ccq(q\in u,d,s)$ systems using coulomb plus Martin potential. Here the two heavy quarks are considered for the diquark states. The same potential form is used for the diquark interaction as well as for the quark-diquark interaction. The chromomagnetic one gluon exchange interaction are perturbatively treated here to get the masses of $J^P={1/2}^{+}$ and $J^P={3/2}^{+}$ states. Accordingly, we obtain $Ξ^{++}_{cc}$ (3519, 3555), $Ξ^{+}_{cc}$ (3527, 3562) and $Ω^{+}_{cc}$ (3648,3688) states of the $ccq$ $({1/2}^{+},{3/2}^{+})$ combinations. Our predictions are in accordance with the SELEX result for $Ξ^{++}_{cc}$ (3519) and other model predictions. Predictions of other properties of these $ccq$ systems will be presented in detail.

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Open flavour Charmed Mesons

We present here recent results on the investigations of the mass spectrum (S-states and P-states), decay constants, decay widths and life time of the D, $D_s$,and $B_c$mesons within the framework of phenomenological potential models.We also present the binding energy and the masses of the di-meson molecular systems with one or more charm meson combinations. Many of the newly found experimental open charm states are identified with the orbital excitations of the conventional open charm mesons while others like X(3872), Y(3930), $D_{sJ}$(2632, 2700) \emph{etc.}, are identified as molecular like states.

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Masses and Magnetic Moments of Charmed Baryons Using Hyper Central Model

Heavy flavour baryons containing one or two charm quarks with light flavour combinations are studied using the hyper central description of the three-body system. The confinement potential is assumed as hyper central coulomb plus power potential with power index $ν$. The ground state masses and the magnetic moments of charmed, $J^P={1/2}^+$ and ${3/2}^+$ baryons are computed for different power index, $ ν$ starting from 0.5 to 2.0.

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Heavy Flavour Baryons in Hyper Central Model

Heavy flavor baryons containing single and double charm (beauty) quarks with light flavor combinations are studied using the hyper central description of the three-body problem. The confinement potential is assumed as hyper central coulomb plus power potential with power index $\upsilon$. The ground state masses of the heavy flavor, $J^P={1/2}^+$ and ${3/2}^+$ baryons are computed for different power index, $ ν$ starting from 0.5 to 2.0. The predicted masses are found to attain a saturated value in each case of quark combinations beyond the power index $ν=1.0$.

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Decay properties of charm and beauty open flavour mesons

The masses of $S$ and $P$ states, pseudoscalar and vector decay constants, leptonic, semileptonic decay widths of charm (D) and beauty (B) open flavour mesons have been computed in the framework of Coulomb and power potential of the form $V(r)=-\frac{α_c}{r}+A r^ν$. The results are compared with other theoretical as well as experimental results.

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