Measurement of the D-+/- production asymmetry in 7 TeV pp collisions

The asymmetry in the production cross-section sigma of D-+/- mesons, Ap = sigma(D+)-sigma(D-)/sigma(D+)-sigma(D-), is measured in bins of pseudorapidity eta and transverse momentum pi within the acceptance of the LHCb detector. The result is obtained with a sample of D+ -> K-s(0)pi(+) decays corresponding to an integrated luminosity of 1.0 fb(-1), collected in pp collisions at a centre of mass energy of 7 TeV at the Large Hadron Collider. When integrated over the kinematic range 2.0 < p(T) < 18.0 GeV/c and 2.20 < eta < 4.75, the production asymmetry is Ap = (-0.96 +/- 0.26 +/- 0.18)%. The uncertainties quoted are statistical and systematic, respectively. The result assumes that any direct CP violation in the D+ -> K-s(0)pi(+) decay is negligible. No significant dependence on eta or p(T) is observed. (C) 2012 CERN. Published by Elsevier B.V. All rights reserved.

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https://infoscience.epfl.ch/record/185487?ln=en

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A search for CP violation in the phase-space structures of 130 and 15 decays to the final states K-K+pi(-)pi(+) and pi(-)pi(+)pi(+)pi(-) is presented. The search is carried out with a data set corresponding to an integrated luminosity of 1.0 fb(-1) collected in 2011 by the LHCb experiment in pp collisions at a centre-of-mass energy of 7 TeV. For the K-K+pi(-)pi(+) final state, the four-body phase space is divided into 32 bins, each bin with approximately 1800 decays. The p-value under the hypothesis of no CP violation is 9.1%, and in no bin is a CP asymmetry greater than 6.5% observed. The phase space of the pi(-)pi(+)pi(+)pi(-). final state is partitioned into 128 bins, each bin with approximately 2500 decays. The p-value under the hypothesis of no CP violation is 41%, and in no bin is a CP asymmetry greater than 5.5% observed. All results are consistent with the hypothesis of no CP violation at the current sensitivity. (C) 2013 CERN. Published by Elsevier B.V. All rights reserved.

Elsevier Science Bv2013