# High-energy photon-hadron scattering in holographic QCD

## Abstract

This article provides an in-depth look at hadron high-energy scattering by using gravity dual descriptions of strongly coupled gauge theories. Just like deeply inelastic scattering (DIS) and deeply virtual Compton scattering (DVCS) serve as clean experimental probes into nonperturbative internal structure of hadrons, elastic scattering amplitude of a hadron and a (virtual) photon in gravity dual can be exploited as a theoretical probe. Since the scattering amplitude at sufficiently high energy (small Bjorken x) is dominated by parton contributions (=Pomeron contributions) even in strong coupling regime, there is a chance to learn a lesson for generalized parton distribution (GPD) by using gravity dual models. We begin with refining derivation of the Brower-Polchinski-Strassler-Tan (BPST) Pomeron kernel in gravity dual, paying particular attention to the role played by the complex spin variable j. The BPST Pomeron on warped spacetime consists of a Kaluza-Klein tower of 4D Pomerons with nonlinear trajectories, and we clarify the relation between Pomeron couplings and the Pomeron form factor. We emphasize that the saddle-point value j* of the scattering amplitude in the complex j-plane representation is a very important concept in understanding qualitative behavior of the scattering amplitude. The total Pomeron contribution to the scattering is decomposed intomore »

- Authors:

- Department of Physics, University of Tokyo, Tokyo 113-0033 (Japan)
- (Japan)
- Institute for the Physics and Mathematics of the Universe, University of Tokyo, Kashiwano-ha 5-1-5, 277-8583 (Japan)

- Publication Date:

- OSTI Identifier:
- 21607827

- Resource Type:
- Journal Article

- Journal Name:
- Physical Review. D, Particles Fields

- Additional Journal Information:
- Journal Volume: 84; Journal Issue: 7; Other Information: DOI: 10.1103/PhysRevD.84.075025; (c) 2011 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0556-2821

- Country of Publication:
- United States

- Language:
- English

- Subject:
- 72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; COMPTON EFFECT; DEEP INELASTIC SCATTERING; DISTRIBUTION; FORM FACTORS; GAUGE INVARIANCE; GRAVITATION; HADRONS; HERA STORAGE RING; KALUZA-KLEIN THEORY; PHOTON-HADRON INTERACTIONS; PHOTONS; POMERANCHUK PARTICLES; QUANTUM CHROMODYNAMICS; SCATTERING AMPLITUDES; SIMULATION; SPACE-TIME; SPIN; STRONG-COUPLING MODEL; AMPLITUDES; ANGULAR MOMENTUM; BASIC INTERACTIONS; BOSONS; DIMENSIONLESS NUMBERS; ELASTIC SCATTERING; ELECTROMAGNETIC INTERACTIONS; ELEMENTARY PARTICLES; FIELD THEORIES; INELASTIC SCATTERING; INTERACTIONS; INVARIANCE PRINCIPLES; LEPTON-BARYON INTERACTIONS; LEPTON-HADRON INTERACTIONS; LEPTON-NUCLEON INTERACTIONS; MASSLESS PARTICLES; MATHEMATICAL MODELS; PARTICLE INTERACTIONS; PARTICLE MODELS; PARTICLE PROPERTIES; QUANTUM FIELD THEORY; QUASI PARTICLES; SCATTERING; STORAGE RINGS; UNIFIED-FIELD THEORIES

### Citation Formats

```
Nishio, Ryoichi, Institute for the Physics and Mathematics of the Universe, University of Tokyo, Kashiwano-ha 5-1-5, 277-8583, and Watari, Taizan.
```*High-energy photon-hadron scattering in holographic QCD*. United States: N. p., 2011.
Web. doi:10.1103/PHYSREVD.84.075025.

```
Nishio, Ryoichi, Institute for the Physics and Mathematics of the Universe, University of Tokyo, Kashiwano-ha 5-1-5, 277-8583, & Watari, Taizan.
```*High-energy photon-hadron scattering in holographic QCD*. United States. doi:10.1103/PHYSREVD.84.075025.

```
Nishio, Ryoichi, Institute for the Physics and Mathematics of the Universe, University of Tokyo, Kashiwano-ha 5-1-5, 277-8583, and Watari, Taizan. Sat .
"High-energy photon-hadron scattering in holographic QCD". United States. doi:10.1103/PHYSREVD.84.075025.
```

```
@article{osti_21607827,
```

title = {High-energy photon-hadron scattering in holographic QCD},

author = {Nishio, Ryoichi and Institute for the Physics and Mathematics of the Universe, University of Tokyo, Kashiwano-ha 5-1-5, 277-8583 and Watari, Taizan},

abstractNote = {This article provides an in-depth look at hadron high-energy scattering by using gravity dual descriptions of strongly coupled gauge theories. Just like deeply inelastic scattering (DIS) and deeply virtual Compton scattering (DVCS) serve as clean experimental probes into nonperturbative internal structure of hadrons, elastic scattering amplitude of a hadron and a (virtual) photon in gravity dual can be exploited as a theoretical probe. Since the scattering amplitude at sufficiently high energy (small Bjorken x) is dominated by parton contributions (=Pomeron contributions) even in strong coupling regime, there is a chance to learn a lesson for generalized parton distribution (GPD) by using gravity dual models. We begin with refining derivation of the Brower-Polchinski-Strassler-Tan (BPST) Pomeron kernel in gravity dual, paying particular attention to the role played by the complex spin variable j. The BPST Pomeron on warped spacetime consists of a Kaluza-Klein tower of 4D Pomerons with nonlinear trajectories, and we clarify the relation between Pomeron couplings and the Pomeron form factor. We emphasize that the saddle-point value j* of the scattering amplitude in the complex j-plane representation is a very important concept in understanding qualitative behavior of the scattering amplitude. The total Pomeron contribution to the scattering is decomposed into the saddle-point contribution and at most a finite number of pole contributions, and when the pole contributions are absent (which we call saddle-point phase), kinematical variable (q,x,t)-dependence of ln(1/q) evolution and ln(1/x) evolution parameters {gamma}{sub eff} and {lambda}{sub eff} in DIS and t-slope parameter B of DVCS in HERA experiment are all reproduced qualitatively in gravity dual. All of these observations shed a new light on modeling of GPD. Straightforward application of those results to other hadron high-energy scattering is also discussed.},

doi = {10.1103/PHYSREVD.84.075025},

journal = {Physical Review. D, Particles Fields},

issn = {0556-2821},

number = 7,

volume = 84,

place = {United States},

year = {2011},

month = {10}

}