H1prelim-04-901

Measurement of Anti-Deuteron Production and a Search for Heavy Stable Charged Particles in Photoproduction at HERA

Reference Publication is expected before DIS2004, Spring 2004
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Contact T. Sloan
Abstract A search has been made for stable heavy charged particles in photoproduction at HERA. A clear anti-deuteron signal is observed but no significant production of heavier particles is detected and upper limits on their production cross sections are given. The photoproduction cross sections for anti-deuterons have been measured at a centre of mass energy W_{/gamma p} 200 GeV in the range 0.3 < pT /M < 0.7 and |y| < 0.4 where pT and y are the tranverse momentum and rapidity of the anti-deuteron of mass M in the laboratory frame. The numbers of anti-deuterons per event are found to be similar in photoproduction to those found in proton-proton collisions at the CERN ISR. However, they are much lower than those found in central Au-Au collisions at RHIC. The coalescence parameter B2, which characterizes the likelihood of anti-nucleus production, has been measured and found to be much higher in photoproduction and pp than in Au-Au collsions at a similar nucleon-nucleon centre of mass energy.
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