Low mass dimuon production in proton and ion induced interactions at SPS
M C. Abreu
,
B. Alessandro
,
C. Alexa
,
R. Arnaldi
,
J. Astruc
(1)
,
M. Atayan
,
C. Baglin
(2)
,
A. Baldisseri
,
A. Baldit
(3)
,
M. Bedjidian
(4)
,
F. Bellaiche
(4)
,
S. Beole
,
V. Boldea
,
P. Bordalo
,
A. Bussiere
(2)
,
V. Capony
(2)
,
L. Casagrande
,
J. Castor
(3)
,
T. Chambon
(3)
,
B. Chaurand
(5)
,
I. Chevrot
(3)
,
B. Cheynis
(4)
,
E. Chiavassa
,
C. Cicalo
,
M P. Comets
(1)
,
N. Constans
(5)
,
S. Constantinescu
,
D. Contardo
(4)
,
A. de Falco
,
G. Dellacasa
,
N. de Marco
,
E. Descroix
,
A. Devaux
(3)
,
S. Dita
,
O. Drapier
(4)
,
B. Espagnon
(3)
,
J. Fargeix
(3)
,
R. Ferreira
,
S N. Filippov
,
F. Fleuret
(5)
,
P. Force
(3)
,
M. Gallio
,
y K. Gavrilov
,
C. Gerschel
(1)
,
P. Giubellino
,
M B. Golubeva
,
M. Gonin
(5)
,
P. Gorodetzky
,
a A. Grigorian
,
J.-Y. Grossiord
(6)
,
F F. Guber
,
A. Guichard
(4)
,
J.P. Guillaud
(2)
,
H. Gulkanyan
,
R. Hakobyan
,
R. Haroutunian
(4)
,
M. Idzik
,
D. Jouan
(1)
,
T L. Karavitcheva
,
L. Kluberg
,
R. Kossakowski
(2)
,
a B. Kurepin
,
Y. Le Bornec
(1)
,
P. Liaud
(2)
,
C. Lourenco
,
M. Mac Cormick
(1)
,
P. Macciotta
,
A. Marzari-Chiesa
,
M. Masera
,
A. Masoni
,
S. Mehrabyan
,
M. Monteno
,
S. Mourgues
(3)
,
A. Musso
,
F. Ohlsson-Malek
(4)
,
P. Petiau
(5)
,
A. Piccotti
,
J.-R. Pizzi
(4)
,
F. Prino
,
G. Puddu
,
C. Quintans
,
C. Racca
(7)
,
L. Ramello
,
S. Ramos
,
P. Rato-Mendes
,
L. Riccati
,
A. Romana
(5)
,
B. Ronceux
(2)
,
I. Ropotar
,
P. Saturnini
(3)
,
E. Scomparin
,
S. Serci
,
R. Shahoyan
,
S. Silva
,
M. Sitta
,
C. Soave
,
P. Sonderegger
,
F. Staley
,
X. Tarrago
(1)
,
N S. Topilskaya
,
G L. Usai
,
J. Varela
,
E. Vercellin
,
N. Willis
(1)
1
IPNO -
Institut de Physique Nucléaire d'Orsay
2 LAPP - Laboratoire d'Annecy de Physique des Particules
3 LPC - Laboratoire de Physique Corpusculaire - Clermont-Ferrand
4 IPNL - Institut de Physique Nucléaire de Lyon
5 LLR - Laboratoire Leprince-Ringuet
6 ALICE
7 IReS - Institut de Recherches Subatomiques
2 LAPP - Laboratoire d'Annecy de Physique des Particules
3 LPC - Laboratoire de Physique Corpusculaire - Clermont-Ferrand
4 IPNL - Institut de Physique Nucléaire de Lyon
5 LLR - Laboratoire Leprince-Ringuet
6 ALICE
7 IReS - Institut de Recherches Subatomiques
M C. Abreu
- Function : Author
B. Alessandro
- Function : Author
C. Alexa
- Function : Author
R. Arnaldi
- Function : Author
M. Atayan
- Function : Author
A. Baldisseri
- Function : Author
S. Beole
- Function : Author
V. Boldea
- Function : Author
P. Bordalo
- Function : Author
L. Casagrande
- Function : Author
B. Cheynis
- Function : Author
- PersonId : 750577
- IdHAL : brigitte-cheynis
- IdRef : 032215606
E. Chiavassa
- Function : Author
C. Cicalo
- Function : Author
N. Constans
- Function : Author
- PersonId : 10152
- IdHAL : nicolas-constans
- IdRef : 145189031
S. Constantinescu
- Function : Author
A. de Falco
- Function : Author
G. Dellacasa
- Function : Author
N. de Marco
- Function : Author
E. Descroix
- Function : Author
S. Dita
- Function : Author
R. Ferreira
- Function : Author
S N. Filippov
- Function : Author
M. Gallio
- Function : Author
y K. Gavrilov
- Function : Author
P. Giubellino
- Function : Author
M B. Golubeva
- Function : Author
P. Gorodetzky
- Function : Author
a A. Grigorian
- Function : Author
F F. Guber
- Function : Author
H. Gulkanyan
- Function : Author
R. Hakobyan
- Function : Author
M. Idzik
- Function : Author
T L. Karavitcheva
- Function : Author
L. Kluberg
- Function : Author
R. Kossakowski
- Function : Author
- PersonId : 16746
- IdHAL : roman-kossakowski
- ORCID : 0000-0003-3842-8531
- IdRef : 225157179
a B. Kurepin
- Function : Author
C. Lourenco
- Function : Author
P. Macciotta
- Function : Author
A. Marzari-Chiesa
- Function : Author
M. Masera
- Function : Author
A. Masoni
- Function : Author
S. Mehrabyan
- Function : Author
M. Monteno
- Function : Author
A. Musso
- Function : Author
F. Ohlsson-Malek
- Function : Author
- PersonId : 21915
- IdHAL : fairouz-malek
- ORCID : 0000-0002-0948-5775
- IdRef : 084171219
A. Piccotti
- Function : Author
F. Prino
- Function : Author
G. Puddu
- Function : Author
C. Quintans
- Function : Author
L. Ramello
- Function : Author
S. Ramos
- Function : Author
P. Rato-Mendes
- Function : Author
L. Riccati
- Function : Author
I. Ropotar
- Function : Author
E. Scomparin
- Function : Author
S. Serci
- Function : Author
R. Shahoyan
- Function : Author
S. Silva
- Function : Author
M. Sitta
- Function : Author
C. Soave
- Function : Author
P. Sonderegger
- Function : Author
F. Staley
- Function : Author
N S. Topilskaya
- Function : Author
G L. Usai
- Function : Author
J. Varela
- Function : Author
E. Vercellin
- Function : Author
Abstract
The low mass dimuon spectra collected in p-U collisions by the NA38 experiment significantly exceeds the total cross section expected from previous analysis, done by other experiments. The `excess' events have a harder \pt\ distribution than the muon pairs from $\eta$ and $\omega$ Dalitz decays, expected to dominate the mass window 0.4--0.65~GeV/$c^2$. We conjecture that the excess events might be due to \qqbar\ annihilations, negligible at low \pt\ but made visible by the \mt\ cut applied in the NA38 data. Taking this assumption to parametrise the p-U spectra, we proceed with the analysis of the S-Cu, S-U and Pb-Pb data, collected by the NA38 and NA50 experiments, where we find that the measured mass spectra does not seem to exceed the expected low mass `cocktail' by more than 20\,\%.