Evidence for a strange dibaryon in the reaction K sup minus d yields X. pi. sup minus at the BNL hypernuclear spectrometer

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

OSTI ID:5468651

Tarem, S

Hadrons made of quark combinations other than three quarks or quark-antiquark have been predicted using the bag model. Of these, an S = {minus}P-wave dibaryon is predicted with a mass around 2150 MeV and a width small enough to be detected. Previous experiments measuring the {Lambda}p missing mass spectrum in the reaction K{sup {minus}}d {yields} {pi}{sup {minus}} {Lambda}p show a strong enhancement at 2130 MeV usually explained as a threshold cusp. At high momentum transfers the spectra suggest the possibility of another resonance at slightly higher mass. Experiment 773 was designed to study the K{sup {minus}}d {yields} {pi}{sup {minus}} {Lambda}p reaction induced by 870 MeV/c kaons at several scattering angles allowing changes in momentum transfer from 156 to over 400 MeV/c. If a P-wave resonance exists near the cusp, the relative strengths of the cusp and that resonance should change enough over this range of momentum transfers to allow to tell them apart. In this experiment K-{pi} events were recorded at K-{pi} angles of 10{degree}, 14{degree}, 18{degree}, 22{degree}, and 26{degree}. In order to distinguish between resonance events and the background events consisting of quasi-free {Lambda} and {Sigma} production and K decay, a range hodoscope was built surrounding the target. By requiring a hit multiplicity of 3 in this hodoscope most of the background events are rejected. A detailed Monte Carlo simulation program of the background and the expected signal was performed. The results indicate that there is evidence for the existence of a P-wave resonance with a mass of 2146.4 {plus minus} 0.3 (stat) {plus minus} 0.4 (syst) MeV and with a width of 12.1 {plus minus} 1.6 (stat) {plus minus} 1.1 (syst) MeV FWHM.

• Research Organization: Brandeis Univ., Waltham, MA (USA)
• OSTI ID: 5468651
• Country of Publication: United States
• Language: English

Related Subjects

645103* -- High Energy Physics-- Particle Interactions & Properties-Experimental-- Strong Interactions & Baryon & Meson Properties
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
BAG MODEL
BARYONS
BOSONS
COMPOSITE MODELS
DECAY
DIBARYONS
ELEMENTARY PARTICLES
ENERGY RANGE
EXTENDED PARTICLE MODEL
FERMIONS
HADRON-HADRON INTERACTIONS
HADRONS
HYPERONS
INTERACTIONS
KAON-DEUTERON INTERACTIONS
KAONS
KAONS MINUS
LAMBDA BARYONS
LAMBDA PARTICLES
MASS
MASS SPECTRA
MATHEMATICAL MODELS
MESON-BARYON INTERACTIONS
MESONS
MEV RANGE
MEV RANGE 100-1000
MISSING MASS
MOMENTUM TRANSFER
MONTE CARLO METHOD
PARTICLE DECAY
PARTICLE DISCRIMINATION
PARTICLE IDENTIFICATION
PARTICLE INTERACTIONS
PARTICLE MODELS
PARTICLE PRODUCTION
PIONS
PIONS MINUS
POSTULATED PARTICLES
PSEUDOSCALAR MESONS
QUARK MODEL
QUARKS
SPECTRA
STRANGE MESONS
STRANGE PARTICLES