Probes of initial-state interactions in dilepton angular distributions

Conference · Fri Jan 01 04:00:00 EST 1982

OSTI ID:6300288

Ralston, J P; Pire, B

We discuss the angular distribution of dileptons d sigma/d/sup 4/Qd OMEGA, emphasizing phase sensitivity as a probe of initial-state interactions in QCD. The coherent nature of Sudakov effects is discussed, along with the presence of imaginary parts related by analyticity. Angular-distribution structure functions which describe interference between longitudinal and transverse virtual photons, e.g., can be used to probe phase differences that depend on large momenta. These evolve according to exp(ic ln ln(Q/sup 2//lambda/sub QCD/sup 2/)) where Q/sup 2/ is a large scale. We report on a complete calculation at O(..cap alpha../sub s//sup 2/) of the q anti q ..-->.. ..gamma..* + gluons channel which confirms the cancellation of small (cutoff) scales, and describe a complementary experiment involving spin. We discuss the limit x ..-->.. 1 of the distribution d sigma/dQ/sup 2/dxdcos theta, and point out an unusual and interesting effect that a momentum-dependent phase can produce here.

• Research Organization: Argonne National Lab., IL (USA); Stanford Linear Accelerator Center, CA (USA)
• DOE Contract Number: W-31109-ENG-38
• OSTI ID: 6300288
• Report Number(s): ANL-HEP-CP-82-67; CONF-8210107-5; ON: DE83010708
• Country of Publication: United States
• Language: English

Related Subjects

645101* -- High Energy Physics-- Particle Interactions & Properties-Experimental-- Electromagnetic Interactions & Properties
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
ANGULAR DISTRIBUTION
ANGULAR MOMENTUM
COMPOSITE MODELS
DISTRIBUTION
ELEMENTARY PARTICLES
FERMIONS
FIELD THEORIES
FUNCTIONS
GLUONS
INTERACTIONS
INTERFERENCE
LEPTONS
MASSLESS PARTICLES
MATHEMATICAL MODELS
MATHEMATICAL SPACE
PAIR PRODUCTION
PARTICLE INTERACTIONS
PARTICLE MODELS
PARTICLE PROPERTIES
PARTON MODEL
PHASE SPACE
PHOTONS
POSTULATED PARTICLES
QUANTUM CHROMODYNAMICS
QUANTUM FIELD THEORY
QUARK-ANTIQUARK INTERACTIONS
SPACE
SPIN
STRUCTURE FUNCTIONS
VIRTUAL PARTICLES