Measurement of the total hadronic cross section in tagged gamma gamma reactions

• Published in: Physical review. D, Particles and fields Particles and fields, 1990-05, Vol.41 (9), p.2667-2674
• Main Authors: Aihara, H, Alston-Garnjost, M, Avery, RE, Barker, AR, Bauer, DA, Bay, A, Belcinski, R, Bingham, HH, Bloom, ED, Buchanan, CD, Caldwell, DO, Chao, HY, Chun, SB, Clark, AR, Cowan, GD, Crane, DA, Dahl, OI, Daoudi, M, Derby, KA, Eastman, JJ, Eberhard, PH, Edberg, TK, Eisner, AM, Erné, FC, Fairfield, KH, Fridman, A, Godfrey, G, Hauptman, JM, Ho, C, Hofmann, W, Kamae, T, Kenney, RW, Khacheryan, S, Kofler, RR, Lambert, DJ, Langeveld, WG, Layter, JG, Lin, WT, Linde, FL, Loken, SC, Lu, A, Lynch, GR, Lys, JE, Madaras, RJ, Magnuson, BD, Marsiske, H, Masek, GE, Mathis, LG, Maxfield, SJ, McNeil, RR, Miller, ES, Nicol, NA, Nygren, DR, Oddone, PJ, Oh, H, Oyang, YT, Paar, HP, Palounek, AP, Park, SK, Pellett, DE, Pripstein, M, Ronan, MT, Ross, RR, Rouse, FR
• Format: Article
• Language: English
• Subjects: 645101 - High Energy Physics- Particle Interactions & Properties-Experimental- Electromagnetic Interactions & Properties; BASIC INTERACTIONS; COMPOSITE MODELS; CROSS SECTIONS; ELECTROMAGNETIC INTERACTIONS; ELEMENTARY PARTICLES; ENERGY RANGE; FERMIONS; FIELD THEORIES; FUNCTIONS; GAS TRACK DETECTORS; GEV RANGE; HADRONS; INTERACTIONS; LINEAR MOMENTUM; MATHEMATICAL MODELS; MEASURING INSTRUMENTS; PARTICLE INTERACTIONS; PARTICLE MODELS; PARTICLE PRODUCTION; PARTON MODEL; PEP STORAGE RINGS; PHOTON-PHOTON INTERACTIONS; PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; POSTULATED PARTICLES; PROJECTION SPARK CHAMBERS; PROPAGATOR; QUANTUM CHROMODYNAMICS; QUANTUM FIELD THEORY; QUARKS; RADIATION DETECTORS; SPARK CHAMBERS; STORAGE RINGS; STRUCTURE FUNCTIONS; TOTAL CROSS SECTIONS; TRANSVERSE MOMENTUM; VECTOR DOMINANCE MODEL
• ISSN: 0556-2821; 1089-4918
• DOI: 10.1103/PhysRevD.41.2667

We present a measurement of the total cross section for {gamma}{gamma}{r arrow}hadrons, with one photon quasireal and the other a spacelike photon of mass squared {minus}{ital Q}{sup 2}. Results are presented as a function of {ital Q}{sup 2} and the {gamma}{gamma} center-of-mass energy {ital W}, with the {ital Q}{sup 2} range extending from 0.2 to 60 GeV{sup 2}, and {ital W} in the range from 2 to 10 GeV. The data were taken with the TPC/Two-Gamma facility at the SLAC {ital e}{sup +}{ital e}{sup {minus}} storage ring PEP, which was operated at a beam energy of 14.5 GeV. The cross section exhibits a gentle falloff with increasing {ital W}. Its {ital Q}{sup 2} dependence is shown to be well described by an incoherent sum of vector-meson and pointlike scattering over most of the observed {ital W} range. Agreement at high {ital Q}{sup 2} is improved if a minimum-{ital p}{sub {ital T}} cutoff (motivated by QCD) is imposed on the pointlike contribution.