Hard quark-quark scattering with exclusive reactions
We have begun a program designed to study hard quark-quark scattering with exclusive reactions, focusing on quasi-elastic two-body reactions with all possible quark flavor exchanges. Examples are ..pi../sup -/p ..-->.. ..pi../sup -/p, rho/sup -/p, ..pi../sup +/..delta../sup -/, K/sup +/..sigma../sup -/, or K..lambda... Of the two-body exclusives, only elastic scattering had been measured at such large t previous to our experiment. By comparing the relative importance of different final states, the energy dependence of the production ratios of these states, the prominence of resonances such as rho/sup -/ over background in this region, and measuring polarizations where accessible, we have collected a large body of data on hard scattering in a completely new domain. Previously, essential all short distance QCD tests have been for inclusive processes. We have taken data with both negative and positive incident beam at 10 GeV/c on a hydrogen target and will present the first results, for ..pi../sup -/p ..-->.. ..pi../sup -/p and rho/sup -/p at THETA/sub cm/ = 90/sup 0/, -t = 9 GeV/sup 2//c/sup 2/. The apparatus consists of a magnetic spectrometer, with Cerenkov particle identification, which selects stable charged particles (protons in this case) at high momentum near 90/sup 0/ in the center-of-mass. A large aperture array of PWCs observes the recoil particle or charged decay products. Cross sections are extremely low, approximately a 1 nb/(GeV/c)/sup 2/ for elastic scattering. We will report on a sample of more than 1000 ..pi../sup -/p elastic events, and on rho/sup -/p, where the rho/sup -/ decay distribution was observed. We find a surprisingly large rho/sup -/p cross section in this large momentum transfer region, with rho/sup -/p about half the elastic cross section, and a striking spin alignment of the rho/sup -/.
- Research Organization:
- Brookhaven National Lab., Upton, NY (USA); Minnesota Univ., Minneapolis (USA); Southeastern Massachusetts Univ., North Dartmouth (USA)
- DOE Contract Number:
- AC02-76CH00016
- OSTI ID:
- 6953701
- Report Number(s):
- BNL-34932; CONF-840757-3; ON: DE84014375
- Resource Relation:
- Conference: 22. international conference on high energy physics, Leipzig, German D.R., 19 Jul 1984; Other Information: Portions are illegible in microfiche products
- Country of Publication:
- United States
- Language:
- English
Similar Records
Comparison of 20 exclusive reactions at large [ital t]
Exclusive wide angle scattering as a test of perturbative quantum chromodynamics
Related Subjects
PION MINUS-PROTON INTERACTIONS
ELASTIC SCATTERING
EXCLUSIVE INTERACTIONS
QUARK-QUARK INTERACTIONS
ANNIHILATION
BROOKHAVEN AGS
HADRON-HADRON INTERACTIONS
MASS
MOMENTUM TRANSFER
ACCELERATORS
BASIC INTERACTIONS
CYCLIC ACCELERATORS
ELECTROMAGNETIC INTERACTIONS
INTERACTIONS
MESON-BARYON INTERACTIONS
MESON-NUCLEON INTERACTIONS
PARTICLE INTERACTIONS
PION-NUCLEON INTERACTIONS
PION-PROTON INTERACTIONS
SCATTERING
SYNCHROTRONS
645204* - High Energy Physics- Particle Interactions & Properties-Theoretical- Strong Interactions & Properties
645104 - High Energy Physics- Particle Interactions & Properties-Experimental- Strong Meson-Induced Interactions- (-1987)