The spin density matrix elements for the rho(0), K-*0(892) and phi produced in hadronic Z(0) decays are measured in the DELPHI detector. There is no evidence for spin alignment of the K-*0(892) and phi, in the region x(p) less than or equal to 0.3 (x(p) = p/p(beam)), where rho(00) = 0.33 +/- 0.05 and rho(00) = 0.30 +/- 0.04, respectively. In the fragmentation region, x(p) greater than or equal to 0.4, there is some indication for spin alignment of the rho(0) and K-*0(892), since rho(00) = 0.43 +/- 0.05 and rho(00) = 0.46 +/- 0.08, respectively. These values are compared with those found in meson-induced hadronic reactions. For the phi, rho(00) = 0.30 +/- 0.04 for x(p) greater than or equal to 0.4 and 0.55 +/- 0.10 for x(p) greater than or equal to 0.7. The off-diagonal spin density matrix element rho(1-1) is consistent with zero in all cases. (C) 1997 Published by Elsevier Science B.V.

Measurement of the spin density matrix for the rho(0), K*(0)(892) and phi produced in Z(0) decays

DE LOTTO, Barbara;SCURI, Fabrizio;
1997-01-01

Abstract

The spin density matrix elements for the rho(0), K-*0(892) and phi produced in hadronic Z(0) decays are measured in the DELPHI detector. There is no evidence for spin alignment of the K-*0(892) and phi, in the region x(p) less than or equal to 0.3 (x(p) = p/p(beam)), where rho(00) = 0.33 +/- 0.05 and rho(00) = 0.30 +/- 0.04, respectively. In the fragmentation region, x(p) greater than or equal to 0.4, there is some indication for spin alignment of the rho(0) and K-*0(892), since rho(00) = 0.43 +/- 0.05 and rho(00) = 0.46 +/- 0.08, respectively. These values are compared with those found in meson-induced hadronic reactions. For the phi, rho(00) = 0.30 +/- 0.04 for x(p) greater than or equal to 0.4 and 0.55 +/- 0.10 for x(p) greater than or equal to 0.7. The off-diagonal spin density matrix element rho(1-1) is consistent with zero in all cases. (C) 1997 Published by Elsevier Science B.V.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11390/884161
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