We report the first observation of charmed mesons with the ZEUS detector at HERA using the decay channel D*+- -->(D0 --> K-pi+) pi+ (+ cc.). Clear signals in the mass difference delta M=M(D*)-M(D0) as as well as in the M(Kpi) distribution at the D0 mass are found. The ep cross section for inclusive D*± production with Q^2 < 4 GeV^2 in the γp centre-of-mass energy range 115 < W < 275 GeV has been determined to be (32±7−7+4) nb in the kinematic region pt(D*) ≥ 1.7 GeV, |eta(D*)| < 1.5. Extrapolating outside this region, assuming a mass of the charm quark of 1.5 GeV, we estimate the ep charm cross section. The increase of the total charm photoproduction cross section by one order of magnitude with respect to low energy data experiments is well described by QCD NLO calculations using singular gluon distributions in the proton.
Study of D* (2010)± production in ep collisions at HERA
ANZIVINO, Giuseppina
1995
Abstract
We report the first observation of charmed mesons with the ZEUS detector at HERA using the decay channel D*+- -->(D0 --> K-pi+) pi+ (+ cc.). Clear signals in the mass difference delta M=M(D*)-M(D0) as as well as in the M(Kpi) distribution at the D0 mass are found. The ep cross section for inclusive D*± production with Q^2 < 4 GeV^2 in the γp centre-of-mass energy range 115 < W < 275 GeV has been determined to be (32±7−7+4) nb in the kinematic region pt(D*) ≥ 1.7 GeV, |eta(D*)| < 1.5. Extrapolating outside this region, assuming a mass of the charm quark of 1.5 GeV, we estimate the ep charm cross section. The increase of the total charm photoproduction cross section by one order of magnitude with respect to low energy data experiments is well described by QCD NLO calculations using singular gluon distributions in the proton.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
