A-2 meson production in pi-minus proton interactions at five BeV

"A study of the A2 meson has been made on data obtained from pi p interactions at 5 BeV/c in the 72""Alvarez liquid hydrogen bubble chamber. The p pi decay mode in the 4-constraint, p pi+ pi- pi- final state is treated in detail. Fit.s to the 3TI invariant mass spectrum yield a central mass value and width of 1.296±.008 and .l05±.035 BeV. respectively, for the A2 when the events are treated as constituting a single resosant particle. Limited statistics render inconclusive an investigation of a possible mass splitting at the center of the A2 peak. A production crosS section of l20±46 ub. for the quasi-two-body reaction. pi- p -> A-2 p, is also obtained from X2 fits to the 3TI mass spectrum. This result is in good agreement with cross. section measurements reported at other incident pion momenta. The spin-parity analysis of the Ppi decay mode yields results p + which are consistent with a J = 2 assignment for both halves of the A2"" The angular distribution of the decay plane indicates a J = 2 spin state with alkl = 1 component along the normal to the decay plane. A projection of the P helicity state population is consistent with a completely transver.se polarization (i.e. t helicity, I A I = 1) for the intermediate p!s from the A2 decay. A calculation of the spin-density matrix elements, assuming a JF= 2+ assignment for the A2, yields results consistent with resonance production via p meson exchange. The values for the density matrix elements are also in.general agreement with those computed from the npi decay mode."

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Physics

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2011

Author dc:creator

• Schafer, Elton Duane

Contributors dc:contributor

• Ascoli, Giulio

• A2 mesons
• hydrogen bubble chamber
• incident pions

Statement dc:rights

• Copyright 1969 Elton Duane Schafer

Language dc:language

en

Identifier

2959302

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/25777