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D. K. Choudhury

Publications and source records attributed to D. K. Choudhury.

At least 19 recordsLinked to original sources
arXiv2024

Analytical models of the Proton Structure Function and the gluon distribution at small x beyond leading order

We incorporate the next-to-leading order (NLO) and the next-to-next-to-leading order (NNLO) effects in the models of the Singlet Structure function F_2^S(x,t) and the gluon distribution G(x,t) using DGLAP equations approximated at small x. Analytical solutions both at the next-to leading order (NLO) as well as the next-to-next-to leading order (NNLO) are obtained. We then make comparisons with exact results.

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arXiv2019

Masses of Heavy Flavour mesons in a space with one finite extra-dimension

Motivated by the recent developments in stability of hydrogen atom in a space with one finite extra-dimension,we consider that physical mesons are also stable in such a space and estimate their masses in a QCD inspired potential model. Our analysis suggests that a model of mesons with linear plus coulomb potential in a space with one finite extra-dimension of size very very less than 10^{-18} m is compatible with the present experimental data of heavy flavour mesons.

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arXiv2019

An Improved Analysis of Masses and Decay Constants of Heavy Flavour Mesons within Variational Approach

We employ the variational method to study the properties such as masses, decay constants, oscillation frequency and branching ratios of leptonic decays of heavy flavour mesons with linear cum coulomb Cornell potential. Gaussian function, Coulomb wave function and Airy function are taken as the trial wave-function of variational method in this study. Our analysis suggests that Gaussian trial wave-function provides results which are in close proximity with the experimental results. We also make a comparison with the results from QCD Sum rules and lattice QCD, as well as with recent PDG data.

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arXiv2019

A model of mesons in finite extra-dimension

Recently,problem of stability of H-atom has been reported in extra-finite dimension,and found out that it is stable in extra-finite dimension of size,$R\leq\frac{a_0}{4}$,where,$a_0$ is the Bohr radius.Assuming that,the heavy flavoured mesons have also such stability controlled by the scale of coupling constant,we obtain corresponding QCD Bohr radius and it is found to be well within the present theoretical and experimental limit of higher dimension.We then study its consequences in their masses using effective string inspired potential model in higher dimension pursued by us.Within the uncertainty of masses of known Heavy Flavoured mesons the allowed range of extra dimension is $L\leq10^{-16}m$,which is well below the present theoretical and experimental limit,and far above the Planck length $\simeq1.5\times10^{-35}$ m.

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arXiv2019

Masses of Heavy-Light mesons with two loop static potential in a Variational approach

In this work, we investigate the masses of a few heavy-light mesons with variational method, taking into account the two-loop effects in the static Cornell potential. Specifically, we consider two wave-function,Gaussian and Coulomb. Our analysis suggests that phenomenologically such approach is more successful in the Heavy flavoured meson sector than the stationary state perturbation theory and other approximation methods.

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arXiv2017

Froissart bound and self-similarity based models of proton structure functions

Froissart Bound implies that the total proton-proton cross-section (or equivalently structure function) cannot rise faster than the logarithmic growth $\log^2 s \sim \log^2 1/x$, where \textit{s} is the square of the center of mass energy and \textit{x} is the Bjorken variable. Compatibility of such behavior with the notion of self-similarity in a model of structure function suggested by us sometime back is now generalized to more recent improved self-similarity based models and compare with recent data as well as with the model of Block, Durand, Ha and McKay. Our analysis suggests that Froissart bound compatible self-similarity based models are possible with $\log^2 1/x$ rise in limited $x-Q^2$ ranges of HERA data, but their phenomenological ranges validity are narrower than the corresponding models having power law rise in $1/x$.

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arXiv2016

A study of structure functions with the DGLAP: equations at small $x$ with $O(x)$ and $O(x ^2 )$

We obtain a pair of second order differential equations in two variables $x$ and $t$ from the coupled DGLAP QCD evolution equations at small $x$ using the standard Taylor series expansion method.To that end we keep terms upto $O(x^2 )$.We use the standard assumption about the relationship between the singlet Structure Function and the gluon distributions available in current literature. We solve the taylor approximated $O(x)$ DGLAP equations by Lagrange's auxiliary method and $O(x^2)$ equation by Method of Separation of Variables and then show that the two solutions obtained in each for $O(x)$ and $O(x^2)$ are not identical in general.Analysis of the results obtained are done in the range of the recent HERA data.

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arXiv2016

Effective String Theory Inspired Potential and Meson Masses in Higher Dimension

Nambu-Goto action in classical bosonic string model for hadrons predicts quark-antiquark potential to be\cite{Nambu-Goto} $V(r)=-\fracγ{r}+σr +μ_0$. In this report we present studies of masses of heavy flavour mesons in higher dimension with our recently developed wave functions obtained following string inspired potential. We report the dimensional dependence of the masses of mesons. Our results suggest that as the meson mass increases with the number of extra spatial dimension, it will attain the Planck scale ($ \sim 10^{19}GeV$) asymptotically at an astronomically large spatial dimension (we call it Planck dimension) $D_{Planck} \sim 10^{11}$, which sets the limit of applicability of Schrodinger equation in large dimension.

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arXiv2016

Isgur-Wise function and a new approach to Potential Model

Considering the Cornell potential $V(r)=-\frac{4α_s}{3r}+br+c$, we have revisited the Dalgarno's method of perturbation by incorporating two scales $r^{short}$ and $r^{long}$ as integration limit so that the perturbative procedure can be improved in a potential model. With the improved version of the wave function the ground state masses of the heavy-light mesons $ D, D_s, B, B_s$ and $B_c $ are computed. The slopes and curvatures of the form factors of semi-leptonic decays of heavy-light mesons in both HQET limit and finite mass limit are calculated and compared with the available data.

hep-ph↗
arXiv2016

RMS and charge radii in a potential model

The Dalgarno's method of perturbation is used to solve the Schrodinger's equation with the Cornell potential $V(r)=-\frac{4α_s}{3r}+br+c$. The short range and long range effect of the potential is incorporated in the same wave function by using two scales $r^S$ and $r^L$ as an integration limit. The results for bounds on r.m.s. radii of various heavy flavored mesons are reported. We have also showed the relation between r.m.s. and charge radius of mesons.

hep-ph↗
arXiv2016

Transverse Momentum Dependent Parton Distributions with self-similarity at small $x$ and models of proton structure function

In this paper we make re-analysis of a self-similarity based model of the proton structure function at small $x$ pursued in recent years. The additional assumption is that it should be singularity free in the entire kinematic range $0\leq \textit{x}\leq 1$. Our analysis indicates that the singularity free version of the model is valid in a more restrictive range of $Q^{2}$. We then analyse the defining Transverse Momentum Dependent Parton Distributions (TMD) occurred in the models and show that the proper generalizations and initial conditions on them not only remove the undesired singularity but also results in a QCD compatible structure function with logarithmic growth in $Q^2$. The phenomenological range of validity is then found to be much larger than the earlier versions. We also extrapolate the models to large $x$ in a parameter free way.

hep-ph↗
arXiv2014

Singularity free analysis of a self-similar model of proton structure function at small \textit{x}

In this paper we make re-analysis of a self-similarity based model of the proton structure function at small \textit{x} pursued in recent years. The additional assumption is that it should be singularity free in the entire kinematic range $0<\textit{x}<1$. Our analysis indicates that the model is valid in a more restrictive range of $Q^{2}$. We also discuss the possibility of incorporation of Froissart saturation condition in the model.

hep-ph↗
arXiv2014

A lower bound on the Longitudinal Structure Function at small x from a self-similarity based model of Proton

Self-similarity based model of proton structure function at small \textit{x} was reported in the literature sometime back. The phenomenological validity of the model is in the kinematical region $ 6.2\, \times \, 10^{-7} \leq x \leq 10^{-2}$ and $ 0.045 \leq Q^{2} \leq 120 \, \mathrm{GeV^{2}} $. We use momentum sum rule to pin down the corresponding self-similarity based gluon distribution function valid in the same kinematical region. The model is then used to compute bound on the longitudinal structure function $F_{L}\left(x,Q^{2} \right)$ for Altarelli-Martinelli equation in QCD and is compared with the recent HERA data.

hep-ph↗
arXiv2014

Self-similarity and the Froissart bound

The Froissart bound implies that the total cross section (or, equivalently, the structure function) cannot rise faster than the logarithmic growth of $ \ln^{2} \left(\frac{1}{x} \right)$. In this work, we show that such a slow growth is not compatible with the notion of self-similarity. As a result, it calls for the modification of the defining transverse-momentum-dependent parton density function (TMD PDF) of a self-similarity based proton structure function $F_{2} \left(x,Q^{2} \right)$ at small \textit{x}. Using plausible assumptions, we obtain the Froissart saturation condition on this TMD PDF.

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arXiv2013

A Higher Dimensional Potential Model Approach in the Study of Isgur-Wise Function for Heavy-Light Mesons

Nambu-Goto action of bosonic string predicts the quark-antiquark potential to be $ V (r) = \fracγ{r} + σr +μ_0 $. The coefficient$ γ= - \frac{π(d-2)}{24} $ is the universal Lüscher coefficient of the Lüscher term $ \fracγ{r}$, which depends upon the space-time dimension `d'. We take linear term in potential as parent and Lüscher term as perturbation for the generation of wave function for meson in d space-time dimension.The wave function comes out in terms of Airy's infinite polynomial series. With this wave function in higher dimension, we then study the Isgur-Wise function for heavy-light mesons and its derivatives.

hep-ph↗
arXiv2013

Leptonic decay of Heavy-light Mesons in a QCD Potential Model

We study the masses and decay constants of heavy-light flavour mesons D, Ds, B and Bs in a QCD Potential model. The mesonic wavefunction is used to compute the masses of D and B mesons in the ground state and the wavefunction is transformed to momentum space to estimate the pseudoscalar decay constants of these mesons. The leptonic decay widths and branching ratio of these mesons for different leptonic channels are also computed to compare with the experimental values. The results are found to be compatible with available data.

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arXiv2012

Isgur-Wise function within a QCD quark model with Airy's function as the wave function of heavy-light mesons

We report some improved wave function for mesons taking linear confinement term in standard QCD potential as parent and Coulombic term as perturbation while applying quantum mechanical perturbation technique in solving Schrodinger equation with such a potential. We find that Airy's infinite series appears in the wave-function of the mesons. We report our calculations on the Isgur-Wise function and its derivatives for heavy-light mesons, within this framework.

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