Angular distributions of muon pairs produced by 194 GeV/c negative pions.

Authors :: Falciano, S.
Guanziroli, M.
Hofer, H.
Lecomte, P.
Coultre, P.
Suter, H.
Telegdi, V.
Viertel, G.
Betev, B.
Freudenreich, K.
Ereditato, A.
Gorini, E.
Strolin, P.
Bordalo, P.
Cerrito, L.
Kluberg, L.
Romana, A.
Salmeron, R.
Varela, J.
Blaising, J.
Source :: Zeitschrift für Physik. C, Particles & Fields; 1986, Vol. 31 Issue 4, p513-526, 14p
Publication Year :: 1986
Abstract: We present the angular distributions of muon pairs obtained in a high-statistics experiment using a 194-GeV/c π impinging on a tungsten target. Our results are based on the analysis of 145,000 events with positive Feynman x and mass above 4.07 GeV/c, excluding the ϒ region. Simple first-order QCD relations allow us to determine the ratio of annihilation with hard-gluon emission to the sum of annihilation with hard-gluon emission and hard-gluon Compton scattering, which is found to be about 58% to 75%. We determine the parton square intrinsic transverse momenta to be of the order of 0.6 (GeV/c), and about 30% larger in the pion than in the nucleon. At large x, our data agree with the higher-twist hypothesis, and support the interpretation of the relevant scale parameter as the dimuon square transverse momentum. [ABSTRACT FROM AUTHOR]