arXiv subjects

Yuya Nakagawa

Publications and source records attributed to Yuya Nakagawa.

3 recordsLinked to original sources

arXiv2017

Gluon orbital angular momentum at small-$x$

We present a general analysis of the orbital angular momentum (OAM) distribution of gluons $L_g(x)$ inside the nucleon with particular emphasis on the small-$x$ region. We derive a novel operator representation of $L_g(x)$ in terms of Wilson lines and argue that it is approximately proportional to the gluon helicity distribution $L_g(x) \approx -2ΔG(x)$ at small-$x$. We also compute longitudinal single spin asymmetry in exclusive diffractive dijet production in lepton-nucleon scattering in the next-to-eikonal approximation and show that the asymmetry is a direct probe of the gluon helicity/OAM distribution as well as the QCD odderon exchange.

hep-ph↗

arXiv2016

A Study of the H-dibaryon in Holographic QCD

We study the H-dibaryon (uuddss) in holographic QCD for the first time. Holographic QCD is derived from a QCD-equivalent D-brane system ($S^1$-compactified D4/D8/$\overline{\rm D8}$) in the superstring theory via the gauge/gravity correspondence. In holographic QCD, all baryons appear as topological chiral solitons of Nambu-Goldstone bosons and (axial) vector mesons. In this framework, the H-dibaryon can be described as an SO(3)-type hedgehog state. We present the formalism of the H-dibaryon in holographic QCD, and perform the calculation to investigate its properties in the chiral limit.

hep-th↗

arXiv2016

1+1 Large $N_c$ QCD and its Holographic Dual -Soliton Picture of Baryons in Single-Flavor World

We study baryons in holographic QCD corresponding to 1+1 dimensional single-flavor ($N_f$=1) QCD for the first time. We formulate 1+1 QCD using an $S^1$-compactified D2/D8/$\overline{\rm D8}$ branes in the superstring theory, and describe the baryon as a topological configuration in 1+1 $N_f$=1 QCD, corresponding to $Π_1({\rm U(1)})={\bf Z}$. Unlike 1+3 QCD with $N_f \ge 2$, however, we find that the low-dimensional baryonic soliton is generally unstable against a scale transformation/variation and swells infinitely in 1+1 $N_f$=1 QCD at the leading of large $N_c$. We thus point out a serious difficulty on the soliton picture of baryons in large $N_c$ in the single-flavor world in both 1+1 and 1+3 QCD. We also compare the low-dimensional holographic baryon with the Abrikosov vortex, i.e., a stable topological configuration in Type-II superconductors.

hep-th↗