Measurement of High Energy Direct Photons in $j Decays*

Content Provider	Semantic Scholar
Author	Brams, G. S. Alam, Mohammed Shah Arun Kishore W. C. Blocker Boyarski, M. Breidenbach, Martin Bregman, Lucy Burke Carithers, W. C. Chinowsky, W. Coles, Murray Cooper Dieterle Dillon Dorenbosch Dorfan, Mannie Eaton, M. W. Feldman Ebrahimi M. Franklin Gidal, Gp Goldhaber, Gerson Hanson, Gilbert Hayes, G. T. Himel Hitlint, G. Hollebeek Innes Jaros Jenni Johnson, Derek Kadyk Lankford Larsen Gth, L. Millikan, E. Nelson Pang Patrick Perl Richter Roussarie Scharre Schindler Schwitters Siegrist Strait Taureg Tonutti, ' M. Trilling Vella Andrew R. Vidal, Enrique Videau Weiss, Marlene Zaccone
Copyright Year	1979
Abstract	We have measured the inclusive y and 1~' momentum distributions at the $. Using these data and estimates of n production, we find that (4.lt0.8)% of Jo d ecays contain a direct photon with energy greater than 60% of the beam energy. The expected momentum distribution for direct photons calculated to lowest-order in QCD is qualitatively different than that observed in the data. I-2-First-order QCD calculations predict that a significant fraction of the hadronic decays of heavy quark-antiquark 3s resonances (such-1 as the $J) result in the production of direct y's (i.e., y's not coming from secondary decays of rots or n's).l We have measured the inclusive y and 1~' momentum distributions at the $, and have made estimates of the n momentum distribution from the data. We observe y production in excess of-the expected contributions from TI ' and n decay. The data were collected with the Mark II magnetic detector at the SLAC e+e-storage ring facility SPEAR at energies near the peak of the $(3095) resonance. The detector has been described in detail elsewhere,2 and only a brief description of the particle detection will be presented in this Letter. Charged tracks are reconstructed from hits in the sixteen cylindrical drift chamber layers which provide solid angle coverage over 85% of 4n sr. The trigger requires two or more charged tracks, one of which must be within the central region of the drift chamber which covers 67% of 4~r sr.
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Alternate Webpage(s)	http://www.slac.stanford.edu/pubs/slacpubs/2250/slac-pub-2415.pdf
Language	English
Access Restriction	Open
Subject Keyword	Charge (electrical) Detectors Energy, Physics Estimated Harvard Mark II Offset binary Photons Resonance Sixteen Supernumerary maxillary right first molar Track (course) anatomical layer
Content Type	Text
Resource Type	Article