Exclusive Two-Photon Processes in QCD

Conference · Fri Dec 02 00:00:00 EST 2005

OSTI ID:877525

Brodsky, Stanley J

Hadron pair production from two-photon annihilation plays an important role in unraveling the perturbative and non-perturbative structure of QCD, first by testing the validity and empirical applicability of leading-twist factorization theorems, second by verifying the structure of the underlying perturbative QCD subprocesses, and third, through measurements of angular distributions and ratios which are sensitive to the shape of the distribution amplitudes. In effect, photon-photon collisions provide a microscope for testing fundamental scaling laws of PQCD and for measuring distribution amplitudes. The determination of the shape and normalization of the distribution amplitude is particularly important in view of their importance in the analysis of exclusive semi-leptonic and two-body hadronic B-decays. The data from the Belle and CLEO collaborations on single and double meson production are in excellent agreement with the QCD predictions. In contrast, the normalization of the nominal leading-order predictions of PQCD for proton pair production appears to be significantly below recent Belle measurements. I also review issues relating to renormalization scale setting.

• Research Organization: SLAC National Accelerator Lab., Menlo Park, CA (United States)
• Sponsoring Organization: USDOE
• DOE Contract Number: AC02-76SF00515
• OSTI ID: 877525
• Report Number(s): SLAC-PUB-11577; TRN: US0601549
• Resource Relation: Conference: Invited talk at Photon: Its First Hundred Years and the Future. Includes PHOTON2005 and PLC2005, Warsaw and Kazimierz, Poland, 30 Aug - 8 Sep 2005
• Country of Publication: United States
• Language: English

Related Subjects

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
73 NUCLEAR PHYSICS AND RADIATION PHYSICS
AMPLITUDES
ANGULAR DISTRIBUTION
ANNIHILATION
FACTORIZATION
HADRONS
MESONS
MICROSCOPES
PAIR PRODUCTION
PHOTON-PHOTON INTERACTIONS
PROTONS
QUANTUM CHROMODYNAMICS
RENORMALIZATION
SCALING LAWS
SHAPE
TESTING
Phenomenology-HEP
HEPPH
HEPTH