Abstract
The photoproduction of D ∗± mesons has been measured with the ZEUS detector at HERA at three different ep centre-of-mass energies, $$ \sqrt{s} $$ , of 318, 251 and 225 GeV. For each data set, D ∗± mesons were required to have transverse momentum, p ∗ , and pseudo-rapidity, η D∗, in the ranges 1.9 < p ∗ < 20 GeV and |η D∗| < 1.6. The events were required to have a virtuality of the incoming photon, Q 2, of less than 1 GeV2. The dependence on $$ \sqrt{s} $$ was studied by normalising to the high-statistics measurement at $$ \sqrt{s}=318 $$ GeV. This led to the cancellation of a number of systematic effects both in data and theory. Predictions from next-to-leading-order QCD describe the $$ \sqrt{s} $$ dependence of the data well.
Highlights
Experimental set-upA detailed description of the ZEUS detector can be found elsewhere [17]. A brief outline of the components that are most relevant for this analysis is given below
Summary
A detailed description of the ZEUS detector can be found elsewhere [17]. A brief outline of the components that are most relevant for this analysis is given below. In the kinematic range of the analysis, charged particles were tracked in the central tracking detector (CTD) [18,19,20] and the microvertex detector (MVD) [21]. These components operated in a magnetic field of 1.43 T provided by a thin superconducting solenoid. The high-resolution uranium-scintillator calorimeter (CAL) [22,23,24,25] consisted of three parts: the forward (FCAL), the barrel (BCAL) and the rear (RCAL) calorimeters. The fractional systematic uncertainty on the measured luminosity [30] was 1.8 %, composed of correlated and uncorrelated uncertainties of, respectively, 1.5% and 1%
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