Angular and Current-Target Correlations in Deep Inelastic Scattering at HERA

Correlations between charged particles in deep inelastic ep scattering have been studied in the Breit frame with the ZEUS detector at HERA using an integrated luminosity of 6.4 pb-1. Short-range correlations are analysed in terms of the angular separation between current-region particles within a cone centred around the virtual photon axis. Long-range correlations between the current and target regions have also been measured. The data support predictions for the scaling behaviour of the angular correlations at high Q2 and for anti-correlations between the current and target regions over a large range in Q2 and in the Bjorken scaling variable x. Analytic QCD calculations and Monte Carlo models correctly describe the trends of the data at high Q2, but show quantitative discrepancies. The data show differences between the correlations in deep inelastic scattering and e+e- annihilation.Comment: 26 pages including 10 figures (submitted to Eur. J. Phys. C

Angular and Current-target Correlations in Deep Inelastic Scattering at HERA

Correlations between charged particles in deep inelastic e+ p scattering have been studied in the Breit frame with the ZEUS detector at HERA using an integrated luminosity of 6.4pb-1. Short-range correlations are analysed in terms of the angular separation between current-region particles within a cone centred around the virtual photon axis. Long-range correlations between the current and target regions have also been measured. The data support predictions for the scaling behaviour of the angular correlations at high Q2 and for anti-correlations between the current and target regions over a large range in Q2 and in the Bjorken scaling variable x. Analytic QCD calculations and Monte Carlo models correctly describe the trends of the data at high Q2, but show quantitative discrepancies. The data show differences between the correlations in deep inelastic scattering and e+e- annihilation

Measurement of inclusive (D-s(+/-)) photoproduction at HERA

The first measurement of inclusive D-s(+/-) photoproduction at HERA has been performed with the ZEUS detector for photon-proton centre-of-mass energies; 130 DsX) = 3.79 +/- 0.59(stat.)(-0.46)(+0.26)(syst.) +/- 0.94(br.) nb, where the last error arises from the uncertainty in the D-s(+/-) decay branching ratio. The measurements are compared with inclusive D*(+/-) photoproduction cross sections in the same kinematic region and with QCD calculations. The D-s(+/-) cross sections lie above a fixed-order next-to-leading order calculation and agree better with a tree-level O(alpha alpha(s)(3)) calculation that was tuned to describe the ZEUS D* (+/-) cross sections. The ratio of D-s(+/-) to D*(+/-) cross sections is 0.41 +/- 0.07(stat.)(-0.05)(+0.03)(syst.) +/- 0.10 (br.). From this ratio, the strangeness-suppression factor in charm photoproduction, within the LUND string fragmentation model, has been calculated to be gamma(s)= 0.27 +/- 0.05 +/- 0.07(br.). The cross-section ratio and gamma(s) are in good agreement with those obtained in charm production in e(+)e(-) annihilation. (C) 2000 Elsevier Science B.V. All rights reserved

Development and validation of a semi-quantitative ultra-high performance liquid chromatography-tandem mass spectrometry method for screening of selective androgen receptor modulators in urine

A semi-quantitative method was developed to monitor the misuse of 15 SARM compounds belonging to nine different families, in urine matrices from a range of species (equine, canine, human, bovine and murine). SARM residues were extracted from urine (200 μL) with tert-butyl methyl ether (TBME) without further clean-up and analysed by ultra-high performance liquid chromatography coupled to tandem mass spectrometry (UHPLC-MS/MS). A 12 min gradient separation was carried out on a Luna Omega Polar C18 column, employing water and methanol, both containing 0.1% acetic acid (v/v), as mobile phases. The mass spectrometer was operated both in positive and negative electrospray ionisation modes (ESI±), with acquisition in selected reaction monitoring (SRM) mode. Validation was performed according to the EU Commission Decision 2002/657/EC criteria and European Union Reference Laboratories for Residues (EU-RLs) guidelines with CCβ values determined at 1 ng mL−1, excluding andarine (2 ng mL−1) and BMS-564929 (5 ng mL−1), in all species. This rapid, simple and cost effective assay was employed for screening of bovine, equine, canine and human urine to determine the potential level of SARMs abuse in stock farming, competition animals as well as amateur and elite athletes, ensuring consumer safety and fair play in animal and human performance sports