Charmed baryon decays observed in e/sup +/e/sup -/ annihilation at SPEAR

Technical Report · Tue Dec 01 00:00:00 EST 1981

DOI:https://doi.org/10.2172/5650770· OSTI ID:5650770

Vella, E N

Various weak decays of the charmed baryon ..lambda../sub c/ are observed in the Mark II detector at the SLAC e/sup +/e/sup -/ storage ring SPEAR. Hadronic decays ..lambda../sub c//sup +/ ..-->.. pK/sup -/..pi../sup +/ and ..lambda../sub c//sup +/ ..-->.. pK/sub s//sup 0/ and their conjugates are observed as peaks in invariant mass spectra at m(..lambda../sub c/) = (2286 +- 6) MeV/c/sup 2/. An estimate of the charmed baryon production cross section, sigma(..lambda../sub c/) + sigma (anti ..lambda../sub c/) = (1.7 +- 0.4) nb, derived from Mark II measurements of the inclusive baryon cross sections R/sub p/ and R/sub ..lambda../ as functions of center-of-mass energy, is used to calculate branching ratios for these hadronic decays: BR (..lambda../sub c//sup +/ ..-->.. p K/sup -/ ..pi../sup +/) = (2.0 +- 0.8)%; BR (..lambda../sub c//sup +/ ..-->.. p k/sub s//sup 0/)/BR (..lambda../sub c//sup +/ ..-->.. p K/sup -/ ..pi../sup +/) = (36 +- 16)%. An attempt is also made to observe higher mass charmed baryons by reconstructing cascade decays ..sigma../sub c/ ..-->.. ..lambda../sub c/..pi... Evidence for the observation of semileptonic decays of the charmed baryon is presented. Direct electrons are observed in events containing antiprotons, lambdas and antilambdas. The number of electrons per baryon event, after background subtraction and efficiency correction, is used, together with an estimate of the charmed baryon content of proton and lambda events, to calculate inclusive and semi-inclusive semileptonic branching ratios of the ..lambda../sub c/.

• Research Organization: Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
• DOE Contract Number: W-7405-ENG-48
• OSTI ID: 5650770
• Report Number(s): LBL-13845; ON: DE82005159; TRN: 82-009353
• Resource Relation: Other Information: Thesis
• Country of Publication: United States
• Language: English

Related Subjects

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
LAMBDA PARTICLES
SEMILEPTONIC DECAY
WEAK HADRONIC DECAY
BRANCHING RATIO
CHARM PARTICLES
CROSS SECTIONS
EXPERIMENTAL DATA
GEV RANGE 01-10
MEASURING METHODS
PARTICLE DECAY
RADIATION DETECTORS
SPEAR
BARYONS
DATA
DECAY
ELEMENTARY PARTICLES
ENERGY RANGE
FERMIONS
GEV RANGE
HADRONS
HYPERONS
INFORMATION
MEASURING INSTRUMENTS
NUMERICAL DATA
POSTULATED PARTICLES
STORAGE RINGS
STRANGE PARTICLES
WEAK PARTICLE DECAY
645104* - High Energy Physics- Particle Interactions & Properties-Experimental- Strong Meson-Induced Interactions- (-1987)
645102 - High Energy Physics- Particle Interactions & Properties-Experimental- Weak Interactions & Properties