Transverse charge and magnetization densities in holographic QCD

Dipankar Chakrabarti,Chandan Mondal

doi:10.1140/epjc/s10052-014-2962-8

Dipankar Chakrabarti, Chandan Mondal

Open Access

https://doi.org/10.1140/epjc/s10052-014-2962-8

Copy DOI

Abstract

We present a study of flavor structures of transverse charge and anomalous magnetization densities for both unpolarized and transversely polarized nucleons. We consider two different models for the electromagnetic form factors in holographic QCD. The flavor form factors are obtained by decomposing the Dirac and Pauli form factors for nucleons using the charge and isospin symmetry. The results are compared with two standard phenomenological parametrizations.

Highlights

Form factors of the nucleons provide us with crucial information about the internal structure of the nucleons and have been measured in many experiments
The charge and magnetization densities in the transverse plane are defined as the Fourier transforms of the electromagnetic form factors
We have presented a detailed study and comparison of the charge and anomalous magnetization densities for nucleons in the transverse plane in two models in AdS/QCD

Summary

Introduction

Form factors of the nucleons provide us with crucial information about the internal structure of the nucleons and have been measured in many experiments. We show the flavor decompositions of the transverse densities of the nucleons in two different models in the framework of AdS/QCD and compare with the two global parametrizations of Kelly [50] and Bradford et al [51]. In the light-front quark model, it is defined as the spin-flip matrix element of the J + current but the AdS action cannot produce this term and the Pauli form factor is put in for phenomenological purposes. Since the action defined in Eq (1) cannot produce the spin-flip (Pauli) form factors, they introduced an additional gauge invariant non-minimal coupling This additional term gives an anomalous contribution to the Dirac form factor. Since the action in Eq (1) cannot produce the spin-flip term, in Model II, a nonminimal coupling term is added to generate the Pauli form factors This additional term gives a contribution to the Dirac form factors . It was shown in [55] that, though the ratio of Pauli and Dirac form factors for the proton is F2p/F1p ∝ 1/Q2, the Q2 dependence is almost constant for the ratio of the quark form factors F2/F1 for both u and d

Transverse charge and magnetization densities

Summary