First results on angular distributions of thermal dileptons in nuclear collisions
Nuclear Experiment
2014-11-18 v1
Abstract
The NA60 experiment at the CERN SPS has studied dimuon production in 158A GeV In-In collisions. The strong excess of pairs above the known sources found in the complete mass region 0.2<M<2.6 GeV has previously been interpreted as thermal radiation. We now present first results on the associated angular distributions. Using the Collins-Soper reference frame, the structure function parameters \lambda, \mu and \nu are measured to be zero, and the projected distributions in polar and azimuth angles are found to be uniform. The absence of any polarization is consistent with the interpretation of the excess dimuons as thermal radiation from a randomized system.
Keywords
Cite
@article{arxiv.0812.3100,
title = {First results on angular distributions of thermal dileptons in nuclear collisions},
author = {NA60 Collaboration and R. Arnaldi and K. Banicz and K. Borer and J. Castor and B. Chaurand and W. Chen and C. Cicalo and A. Colla and P. Cortese and S. Damjanovic and A. David and A. de Falco and A. Devaux and L. Ducroux and H. En'yo and J. Fargeix and A. Ferretti and M. Floris and A. Foerster and P. Force and N. Guettet and A. Guichard and H. Gulkanian and J. M. Heuser and M. Keil and L. Kluberg and Z. Li and C. Lourenco and J. Lozano and F. Manso and P. Martins and A. Masoni and A. Neves and H. Ohnishi and C. Oppedisano and P. Parracho and P. Pillot and T. Poghosyan and G. Puddu and E. Radermacher and P. Ramalhete and P. Rosinsky and E. Scomparin and J. Seixas and S. Serci and R. Shahoyan and P. Sonderegger and H. J. Specht and R. Tieulent and G. Usai and R. Veenhof and H. K. Woehri},
journal= {arXiv preprint arXiv:0812.3100},
year = {2014}
}
Comments
Submitted to Physical Review Letters