Research
I work on the broad area of physics classified as Theoretical Nuclear Physics. I'm interested in anything that has a nucleon in it. Below, I describe a few research projects I've worked on in the past and the ones I'm currently interested in.
Meson phenomenology
Past works
Current Interests
Meson phenomenology
My current project is a study of the
spectrum and decays of the conventional and exotic mesons. We studied the partial wave structure of the decays of the mesons using a model Lagrangian. Our analysis, using the so-called covariant helicity formalism, suggests that the higher order interactions become as important as the lowest order interactions when the 3-momentum carried by the decay products become large. This work was published in PhysRevD.
Exotic mesons are QCD bound
states of quarks and anti-quarks with gluons. The presence of gluons as
an explicit degree of freedom is needed to account for the unusual
quantum numbers. In a recent work, we have studied the decays of hybrid states with quantum numbers 1-+. The preprint can be found here.
Effective Field Theory
Lepton-proton scattering is arguably the single most important tool in
understanding the structure of the proton. The fact that the
cross-section for the process differs from the Mott cross-section
implies that a proton is a composite particle. The ratio of
lepton-proton scattering cross-section to the Mott cross-section gives
us the so-called form factors of the proton. A vast amount of data has
been collected and analyzed so far from various experiments from all
over the world. At present, two issues plague the scattering problem.
- At high momentum transfers, the scattering cross-section derived using two different experimental techniques lead to different form factors for the proton.
- At zero momentum transfer limit, the first derivative of the electric form factor should give us the root-mean-square radius of the proton. However, the rms radius derived from electron-proton scattering data and that derived from the muonic hydrogen Lamb shift measurements differ by as large as 5σ standard deviations. This is called the "proton radius puzzle".
Past works
Nucleon-Nucleon Interaction
My Ph.D. thesis is based on the study of the NN interaction in the singlet (1S0) and triplet (3S1) channels using a nonrelativistic quark model (NRQM). The Hamiltonian consisted of the kinetic energy of the quarks, harmonic confinement potential, and quark-quark interaction potentials. The interaction potentials included the one-gluon exchange potential (OGEP), the instanton induced interaction (III) potential and the one-pion exchange potential (OPEP). I studied the contributions of the various parts of the interaction potentials to the NN interaction. This study was published in PhysRevC.
Extending this, I studied the effects of the finite size of the constituent quarks on the NN interaction. To this end, I replaced the delta function part of the OGEP and III by a Gaussian function and studied the effect of the smearing of the potential by varying the quark size parameter (r0). This study was the first of its kind. This study was motivated by the fact that constituent quarks are quasi-particles and hence, their effective size must influence the interaction between the nucleons. This study was published in JPhysG.
Extending this, I studied the effects of the finite size of the constituent quarks on the NN interaction. To this end, I replaced the delta function part of the OGEP and III by a Gaussian function and studied the effect of the smearing of the potential by varying the quark size parameter (r0). This study was the first of its kind. This study was motivated by the fact that constituent quarks are quasi-particles and hence, their effective size must influence the interaction between the nucleons. This study was published in JPhysG.