The reactions
pp→
p
f
(
X
0)
p
s
, where
X
0 is observed decaying to
π
0
π
0
π
0
π
0 ,
π
+
π
−
π
+
π
− and
π
+
π
−
π
0
π
0 , have been studied at 450 GeV/
c. There is evidence for an
a
2(1320)
π ...decay mode of the
η
2(1645) and
η
2(1870) in the
π
+
π
−
π
0
π
0 and
π
+
π
−
π
+
π
− final states. The
f
2(1950) is consistent with being a single resonance with a dominant
f
2(1270)
ππ decay mode. The
f
0(1370) is found to decay dominantly to
ρρ while the
f
0(1500) is found to decay to
ρρ and
σσ.
Resonance production at ALICE: ρ and ϕ Bhasin, A.; Evans, D.; Jones, G. T. ...
Indian journal of physics,
12/2010, Letnik:
84, Številka:
12
Journal Article
Recenzirano
Resonances in heavy ion experiments provide information about the medium produced in the collisions, in particular about the later stages in the evolution of the fireball. The motivation for the ...study of resonances at ALICE, specifically the
ρ
and
ϕ
mesons, is discussed. The findings of Monte Carlo studies for
ρ
produced in Pb-Pb collisions are outlined, and a fit to the
π
+
π
−
spectrum, including other contributions, is presented. The
ϕ
shape, which shows some distortion, is discussed. The
ρ
meson has a narrow width, making it more easily visible, so its significance without Particle IDentification, or PID, has been investigated. Recent work on the ϕ meson in simulated pp collisions is described, including a fit to the K
+
K
−
spectrum with no PID.
In this Letter we present additional experimental characteristics of anomalous soft photon radiation observed in π−p interactions at 280 GeV/c in the CERN experiment WA91, together with a ...re-calculated ratio of the observed direct soft photon signal to the expected level of the hadronic inner bremsstrahlung, which is found to be 5.3±1.0. The other presented characteristics, energy dependence and angular distributions of direct soft photons, show the similarity of the observed signal to the expected hadronic bremsstrahlung behaviour.
ALICE will measure the properties of strongly interacting matter created in heavy-ion collisions. In addition, taking advantage of the low
p
t
acceptance in the central barrel, ALICE will play an ...important role in understanding
pp
collisions with minimum bias triggers at LHC energies. The proposed minimum bias trigger is sensitive to about 90% of the total inelastic cross section and 99% of the non-diffractive cross section. A procedure to calculate the trigger efficiency and an estimate of the systematic uncertainty due to the limited acceptance of the detector are presented.
The production and decay properties of the
f
0(1370),
f
0(1500),
f
0(2000) and
f
2(1950) have been studied in central pp interactions at 450 GeV/c. The
dP
T
,
φ and |
t| distributions of these ...resonances are presented. For the
J=0 states, the
f
0(1370) and
f
0(2000) have similar
dP
T
and
φ dependences. These are different to the
dP
T
and
φ dependences of the
f
0(980),
f
0(1500) and
f
0(1710). For the
J=2 states the
f
2(1950) has different dependences to the
f
2(1270) and
f
2
′(1520). This shows that the
dP
T
and
φ dependences are not just
J phenomena.
A coupled channel analysis of the centrally produced
K
+
K
−and
π
+
π
−final states has been performed in
pp collisions at an incident beam momentum of 450 GeV/c. The pole positions and branching ...ratios to
ππ and
K
K
of the
f
0(980),
f
0(1370),
f
0(1500) and
f
0(1710) have been determined. A systematic study of the production properties of all the resonances observed in the
π
+
π
−and
K
+
K
−channels has been performed.
Results are presented on hyperon and antihyperon production in Pb–Pb, pPb and pBe collisions at 158 GeV/c per nucleon. Λ, Ξ and Ω yields have been measured at central rapidity and medium transverse ...momentum as functions of the centrality of the collision. Comparing the yields in Pb–Pb to those in pBe interactions, strangeness enhancement is observed. The enhancement increases with the centrality and with the strangeness content of the hyperons, reaching a factor of about 20 for the Ω in the central Pb–Pb collisions
The transverse mass spectra of K0s, Lambda, Xi and Omega particles produced in Pb-Pb collisions at 40 A GeV/c have been studied for a sample of events corresponding to the most central 53% of the ...inelastic Pb-Pb cross-section. We analyze the distributions in the framework of a parameterized model inspired by hydrodynamics. The dependence of the freeze-out parameters on particle species and event centrality is discussed and comparisons with results at higher energy are shown.
A partial wave analysis of the centrally produced eta pi0 and eta pi- channels has been performed in pp collisions using an incident beam momentum of 450 GeV/c. Clear a0(980) and a2(1320) signals ...have been observed in S and D+ waves respectively. The dPT, phi and |t| distributions of these resonances are presented.
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