Photoproduction of. rho. prime mesons in reactions. gamma. p yields p2. pi. sup + 2. pi. sup minus and. gamma. p yields p. pi. sup +. pi. sup minus 2. pi. sup 0 at 20 GeV

Thesis/Dissertation · Fri Jan 01 04:00:00 EST 1988

OSTI ID:7241909

Dingus, P J

From over 300,000 hadronic events gathered by the BC72/73 collaboration, which directed a 20GeV photon beam onto a liquid hydrogen target, the reaction {gamma}p {yields} pp{prime} was isolated in the channels {gamma}p {yields} p2{pi}{sup +}2{pi}{sup {minus}} and {gamma}p {yields} p{pi}{sup +}{pi}{sup {minus}}2{pi}{sup 0}. Subsequently various Monte Carlo models of the {rho}{prime} decaying into four pions in the charge states 2{pi}{sup +}2{pi}{sup {minus}} and {pi}{sup +}{pi}{sup {minus}}2{pi}{sup 0} were fit to the data in all pertinent kinematic variables along with the decay angular distributions and various assumed backgrounds that had not been disentangled. The results of this analysis are: (1) the photoproduced {rho}{prime} conserves S channel helicity, this is shown by an analysis of the angle {Phi}, as described in the text, and by the Density Matrix Elements, (DME), of the {rho}{prime} in the channel {gamma}p {yields} p2{pi}{sup +}2{pi}{sup {minus}}. The DMEs, through the Parity Asymmetry, also show the {rho}{prime} production to be mostly due to natural parity exchange in the t channel. (2) The dominant decay mode of the {rho}{prime} is via {rho}{prime} {yields} {pi}A{sub 1}, this is shown by the absence of a {rho}{sup 0} signal in the channel {gamma}p {yields} p{pi}{sup +}{pi}{sup {minus}}2{pi}{sup 0} and by the approximate equality of the {rho}{prime} cross sections in the two channels. The {rho}{prime} cross section in the channel {gamma}p {yields} p2{pi}{sup +}2{pi}{sup {minus}} is measured to be 0.944 {plus minus} 0.05{mu}b and the {rho}{prime} cross section in the channel {gamma}p {yields} p{pi}{sup +}{pi}{sup {minus}}2{pi}{sup 0} is measured to be 1.19 {plus minus} 0.089{mu}b. (3) The {rho}{prime} mass and width in the channel {gamma}p {yields} p2{pi}{sup +}2{pi}{sup {minus}} are determined to be 1.20 {plus minus} 0.05 GeV and 0.535 {plus minus} 0.04GeV respectively.

• Research Organization: California Univ., Berkeley, CA (USA)
• OSTI ID: 7241909
• Country of Publication: United States
• Language: English

Related Subjects

645000 -- High Energy Physics
645100* -- High Energy Physics-- Particle Interactions & Properties-Experimental
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
BASIC INTERACTIONS
BOSONS
DATA
ELECTROMAGNETIC INTERACTIONS
ELEMENTARY PARTICLES
ENERGY RANGE
EXPERIMENTAL DATA
GEV RANGE
HADRONS
INFORMATION
INTERACTIONS
MEASURING INSTRUMENTS
MEASURING METHODS
MESONS
NUMERICAL DATA
PARTICLE INTERACTIONS
PARTICLE PRODUCTION
PHOTON-BARYON INTERACTIONS
PHOTON-HADRON INTERACTIONS
PHOTON-LEPTON INTERACTIONS
PHOTON-NEUTRINO INTERACTIONS
PHOTON-NUCLEON INTERACTIONS
PHOTON-PROTON INTERACTIONS
PHOTOPRODUCTION