Περίληψη:
Results are presented on dimuon production for invariant masses ranging
from the dimuon threshold up to the J/Psi meson. Proton-tungsten and
sulphur-tungsten interactions at 200 GeV/c/nucleon were measured over a
large kinematic region, using the HELIOS/3 dimuon spectrometer at the
CERN SPS. In the continuum regions between the dimuon threshold and the
rho/omega mesons, and between the phi and J/Psi mesons, an excess is
observed in S-W interactions relative to minimum bias p-W interactions.
The observed excess is continuous over the explored mass range and has
no apparent resonant structure. In the low mass region the dimuon yield
increases by (76 +/- 4)% of the corresponding p-W dimuon spectrum,
whereas in the higher mass region the excess amounts to 2.4 +/- 0.3
times the p-W yield. The observed excess for the low mass region follows
an exponential transverse mass distribution with an average inverse
slope parameter T of (190 +/- 5) MeV/c(2), constant for all but the
lowest charged multiplicity interval and consistent with the slope of
the excess in the higher mass region. In the invariant mass range of
1.35-2.5 GeV/c(2) the continuum dimuon mass distribution observed in p-W
interactions can be quantitatively understood as a sum of three expected
contributions (vector meson decays, semileptonic charm decays and
Drell-Yan process), but both in central and in minimum bias S-W
interactions an excess is observed with respect to these sources which
does not depend on centrality, nor very strongly on the transverse
momentum.
Συγγραφείς:
Angelis, ALS
Antos, J
Beaulieu, M
Beker, H
Bystricky, J
and Catanesi, MG
Cerello, P
Dagan, S
Dellacasa, G
Di
Liberto, S
Dolgoshein, B
Esten, M
Fabjan, CW
Gaidot, A
and Gallio, M
Giubellino, P
Goerlach, U
Guerra, C
Hamel,
LA
Konovalov, S
Kralik, I
London, G
Martelli, F and
Martin, JP
Masera, M
Mazzoni, MA
Meddi, F
Muciaccia, MT
and Muraviev, S
Nomerotsky, A
Oren, Y
Pansart, JP and
Poulard, G
Ramello, L
Riccati, L
Rosa, G
Sandor, L and
Sarris, M
Scomparin, E
Shmeleva, A
Simone, S
Smirnov, S
and Taras, P
Urban, J
Vercellin, E
HELIOS 3 Collaboration
