The production of the excited charm mesons D-1 (2420) and D-2*(2460) in ep collisions has been measured with the ZEUS detector at HERA using an integrated luminosity of 373 pb(-1). The masses of the neutral and charged states, the widths of the neutral states, and the helicity parameter of D-1(2420)(0) were determined and compared with other measurements and with theoretical expectations. The measured helicity parameter of the D-1(0) allows for some mixing of S- and D-waves in its decay to D*(+/-)pi(-/+). The result is also consistent with a pure D-wave decay. Ratios of branching fractions of the two decay modes of the D-2*(2460)(0) and D-2*(2460)(+/-) states were measured and compared with previous measurements. The fractions of charm quarks hadronising into D-1 and D-2* were measured and are consistent with those obtained in e(+)e(-). annihilations. (C) 2012 Elsevier B.V. All rights reserved.
Production of the excited charm mesons D-1 and D-2* at HERA
BRUGNERA, RICCARDO;CARLIN, ROBERTO;GARFAGNINI, ALBERTO;A. Longhin;
2013
Abstract
The production of the excited charm mesons D-1 (2420) and D-2*(2460) in ep collisions has been measured with the ZEUS detector at HERA using an integrated luminosity of 373 pb(-1). The masses of the neutral and charged states, the widths of the neutral states, and the helicity parameter of D-1(2420)(0) were determined and compared with other measurements and with theoretical expectations. The measured helicity parameter of the D-1(0) allows for some mixing of S- and D-waves in its decay to D*(+/-)pi(-/+). The result is also consistent with a pure D-wave decay. Ratios of branching fractions of the two decay modes of the D-2*(2460)(0) and D-2*(2460)(+/-) states were measured and compared with previous measurements. The fractions of charm quarks hadronising into D-1 and D-2* were measured and are consistent with those obtained in e(+)e(-). annihilations. (C) 2012 Elsevier B.V. All rights reserved.Pubblicazioni consigliate
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