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Off-diagonal helicity density matrix elements for vector mesons produced at LEP

  • M. Anselmino
  • M. Bertini
  • F. Murgia
  • P. Quintairos
Theoretical physics

Abstract.

Final state \(q\bar q\) interactions may give origin to non-zero values of the off-diagonal element \(\rho_{1,-1}\) of the helicity density matrix of vector mesons produced in \(e^+ e^-\) annihilations, as confirmed by recent OPAL data on \(\phi\) and \(D^*\)'s. Predictions are given for \(\rho_{1,-1}\) of several mesons produced at large \(z\) and small \(p_T\), i.e. collinear with the parent jet; the values obtained for \(\phi\) and \(D^*\) are in agreement with data. The fragmentation functions of quarks and gluons into photons are studied beyond the Leading Logarithm approximation. We address the nature of the initial conditions of the evolution equation solutions and study problems related to factorization scheme invariance. The possibility of measuring these distributions in LEP experiments is discussed, and a comparison with existing data is made.

Keywords

Matrix Element Evolution Equation Opal Data State Interaction Vector Meson 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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Copyright information

© Springer-Verlag Berlin Heidelberg 1998

Authors and Affiliations

  • M. Anselmino
    • 1
  • M. Bertini
    • 1
  • F. Murgia
    • 2
  • P. Quintairos
    • 1
  1. 1. Dipartimento di Fisica Teorica, Università di Torino and INFN, Sezione di Torino, Via P. Giuria 1, I-10125 Torino, Italy IT
  2. 2. INFN, Sezione di Cagliari, Via A. Negri 18, I-09127 Cagliari, Italy IT

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