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Precision measurement of the {Sigma}{sup 0} hyperon mass

Description: The research that is described in this paper is part of a program to study strong interaction mechanisms in proton proton collisions. The program consists of two experiments: Brookhaven E766 in which we studied the reactions pp {yields} p+ all charged particles with 27.5 GeV/c incident protons and Fermilab E690 in which we studied the reactions pp {yields} p+ all charged particles with 800 GeV/c incident protons. In these experiments, we employed state-of-the-art data acquisition sys- tems and acquired large samples of data: at Brookhaven we amassed 300 million high multiplicity events and at Fermilab, 5.5 billion events. Our uncertainty in the {Sigma}{sup 0} mass is more than 7 times smaller than the best previous result and was based on 16 times the statistics. Likewise, the {Sigma}{sup 0} - {Lambda}{sup 0} mass difference is more than 14 times more accurate than the previous best result. Finally, we note that this measurement is the first direct measurement of the {Sigma}{sup 0} mass.
Date: February 17, 1998
Creator: Wang, M.H.L.S.; Hartouni, E.P. & Kreisler, M.N.
Partner: UNT Libraries Government Documents Department

Measurement of the sigma^o Lifetime

Description: The Coulomb production of {Sigma}{sup 0} hyperons on uranium and nickel nuclei has been measured in a beam of {Lambda} hyperons at the CERN Proton Synchrotron. The results for the {Sigma}{sup 0} lifetime, {tau}{Sigma}{sup 0} = (0.58 {+-} 0.13) x 10{sup -19} sec, and for the {Sigma}{sup 0}-{Lambda} magnetic transition moment, |{mu}{Sigma}{sub {Lambda}}| = (1.82{sub -0.18}{sup +0.25}) nuclear magnetons, are in agreement with SU(3) predictions.
Date: March 1, 1972
Creator: Devlin, T.J.; U., /Rutgers; March, R.H.; Pondrom, L.G.; U., /Wisconsin; Overseth, O.E. et al.
Partner: UNT Libraries Government Documents Department

Associated {Lambda} production at Jefferson Lab

Description: The {sup 1}H(e, e{prime}K{sup +}){Lambda} and {sup 1}H(e, e{prime}K{sup +}){Sigma}{sup 0} reactions were studied as a function of the squared four-momentum-transfer, Q{sup 2}, and the virtual photon polarization, {var_epsilon}, thus enabling the separation of the longitudinal and transverse parts of the cross section. The existence of a sensibly large longitudinal component for the {sup 1}H(e, e{prime}K{sup +}){Lambda} reaction seems to be sustained by these data.
Date: December 31, 1997
Creator: Niculescu, G.; Baker, O.K.; Avery, S. & Collaboration, E93018
Partner: UNT Libraries Government Documents Department

Quantum size effects in classical hadrodynamics

Description: The author discusses future directions in the development of classical hydrodynamics for extended nucleons, corresponding to nucleons of finite size interacting with massive meson fields. This new theory provides a natural covariant microscopic approach to relativistic nucleus-nucleus collisions that includes automatically spacetime nonlocality and retardation, nonequilibrium phenomena, interactions among all nucleons, and particle production. The present version of the theory includes only the neutral scalar ({sigma}) and neutral vector ({omega}) meson fields. In the future, additional isovector pseudoscalar ({pi}{sup +}, {pi}{sup {minus}}, {pi}{sup 0}), isovector vector ({rho}{sup +}, {rho}{sup {minus}}, {rho}{sup 0}), and neutral pseudoscalar ({eta}) meson fields should be incorporated. Quantum size effects should be included in the equations of motion by use of the spreading function of Moniz and Sharp, which generates an effective nucleon mass density smeared out over a Compton wavelength. However, unlike the situation in electrodynamics, the Compton wavelength of the nucleon is small compared to its radius, so that effects due to the intrinsic size of the nucleon dominate.
Date: March 1, 1994
Creator: Nix, J. R.
Partner: UNT Libraries Government Documents Department