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Alka Upadhyay

Publications and source records attributed to Alka Upadhyay.

26 records · Page 2Linked to original sources
arXiv2016

Heavy-light charm mesons spectroscopy and decay widths

We present the mass formula for heavy-light charm meson for one loop, using heavy quark effective theory. Formulating an effective Lagrangian, the masses of the ground state heavy mesons have been studied in the heavy quark limit including leading corrections from finite heavy quark masses and nonzero light quark masses using a constrained fit for the eight equation having eleven parameters including three coupling constants g, h and g'. Masses determined from this approach is fitted to the experimentally known decay widths to estimate the strong coupling constants, showing a better match with available theoretical and experimental data

hep-ph↗
arXiv2015

Study of 1D stranged-charm meson family using HQET

Recently LHCb predicted spin 1 and spin 3 states D* s1(2860) and D* s3(2860) which are studied through their strong decays, and are assigned to fit the 13D1and 13D3 states in the charm spectroscopy. In this paper,using the heavy quark effective theory, we state that assigning D*s1(2860) as the mixing of 13D1 - 23S1 states, is rather a better justification to its observed experimental values than a pure state. We study its decay modes variation with hadronic coupling constant gxh and the mixing angle . We appoint spin 3 state D* s3(2860) as the missing 1D 3- JP state, and also study its decay channel behavior with coupling constant gyh. To appreciate the above results, we check the variation of decay modes for their spin partners states i.e. 1D2 and 1D'2 with their masses and strong coupling constant i.e. gxh and gyh. Our calculation using HQET approach give mixing angle between the 13D1 - 23S1 state for D* s1(2860) to lie in the range (-1.6 radians < theta < -1.2 radians). Our calculation for coupling constant values gives gxh to lie between value 0:17 < gxh < 0:20 and gyh to be 0.40. We expect from experiments to observe this mixing angle to verify our results.

hep-ph↗
arXiv2015

Magnetic moments of JP = 3/2+ decuplet baryons using statistical model

A suitable wave function for baryon decuplet is framed with inclusion of sea containing quark- gluon Fock states. Relevant operator formalism is applied to calculate magnetic moments of JP = 3 2 + baryon decuplet. Statistical model assumes decomposition of baryonic state in various quark-gluon Fock states such as jqqqijgi; jqqqijggi; jqqqijgggi with possibility gluon emitting qq pairs condensates due to the subprocesses like g , qq; g , gg and g , qg where qq = uu; dd; ss. Statistical approach and detailed balance principle in combination is used to find the relative probabilities of these Fock states in avor, spin and color space. The total number of partons (sea) in this formalism are restricted to three gluons due to limited free energy of gluon and suppressed number of strange quark-antiquark pairs. The combined approach is used to calculate the magnetic moments, importance of strangeness in the sea (scalar, vector and tensor). Our approach has confirmed the scalar-tensor sea dominancy over vector sea. Various modifications in the model are used to check the validity of statistical approach. The results are matched with theoretical data available. Good consistency with the experimental data have been achieved for Delta++, Delta+ and Omega-.

hep-ph↗
arXiv2015

Strong Decay widths and Coupling Constant of Recent Charm Meson States

Using an effective Lagrangian approach based on heavy quark symmetry and chiral dynamics, we explore the strong decay widths and branching ratios of various resonances and suggest their JP find the coupling constants involved in the strong decays through pseudoscalar mesons. The present work also discusses about the possible spin-parity assignments of recently observed states by LHCb collaboration.

hep-ph↗
arXiv2011

Some Aspects of Low Energy Properties of Nucleons

We conclude that nucleon is a many body complex system whose low-energy behaviour is determined mainly by strong interaction. Non-perturbative approach to QCD, such as QCD sum rule and the QCD based effective theory, and the models such as a statistical model, have a complementary role in exposing different aspects of nucleonic properties.

hep-ph↗
arXiv2005

Gluonic contribution to the nucleon self-energy in an effective theory

Gluonic contributions to the self-energy of a nucleon have been investigated in an effective theory. The couplings of the topological charge density to nucleons give rise to OZI violating nucleon interactions. The one-loop self-energy of a nucleon arising due to these interactions have been calculated using a heavy baryon chiral perturbation theory. The divergences have been regularized using form factors. The nontrivial structure of the QCD vacuum has also been taken into account.

hep-ph↗
arXiv2003

Spin Studies of Nucleons in a Statistical Model

We decompose various quark-gluon Fock states of a nucleon in a set of states in which each of the three-quark core and the rest of the stuff, termed as a sea, appears with definite spin and color quantum number, their weight being determined, statistically, from their multiplicities. The expansion coefficients in the quark-gluon Fock states have been taken from a recently proposed statistical model. We have also considered two modifications of this model with a view to reduce the contributions of the sea components with higher multiplicities. With certain approximations, we have calculated the quark contributions to the spin of the nucleon,the ratio of the magnetic moments of nucleons, their weak decay constant, and the ratio of SU(3) reduced matrix elements for the axial current. A reasonably close agreement with the corresponding experimental values have been obtained in all the three cases.

hep-ph↗