During the 1996 lead run time, CERES has accumulated 42 million events, corresponding to a factor of 5 more statistics than in 1995 and 2.5 million events of a special photon-run. We report on the ...results of the low-mass e
+e
−-pair analysis. Since the most critical item is the poor signal-to-background ratio we also discuss the understanding of this background, in absolute terms, with the help of a detailed Monte Carlo simulation. We show preliminary results of the photon analysis and summarize the results of the hadron analysis preliminarily reported on already at QM'97 1.
We report a measurement of low-mass electron pairs observed in 158 GeV/nucleon Pb-Au collisions. The pair yield integrated over the range of invariant masses 0.2 ≤
m≤ 2.0 GeV/c
2 is enhanced by a ...factor of 3.5 ± 0.4 (stat) ± 0.9 (syst) over the expectation from neutral meson decays. As observed previously in S-Au collisions, the enhancement is most pronounced in the invariant-mass region 300-700 MeV/c
2. For Pb-Au we find evidence for a strong increase of the enhancement with centrality. In addition, we show that the enhancement covers a wide range in transverse momentum, but is largest at the lowest observed
p
⊥.
The CERES/NA45 collaboration measured, at the CERN SPS, low-mass electron pair production in Pb
Au collisions at 158 A GeV/c incident momentum. In this paper we present an analysis of the data taken ...during the SPS Pb-beam period in the fall of 1995. The results confirm previous findings of CERES showing that the pair production in the mass range 0.2 <m
ee < 1.5 GeV/c
2, when scaled to the ion case with the event multiplicity, is enhanced over the expected yield from the known hadronic sources in pp collisions. A comparison of the results for different multiplicity bins indicates that the excess increases faster than linearly with charged-particle multiplicity. We also present the transverse-momentum distributions of the observed pairs.
The pulmonary artery-wedge and left atrial pressures were recorded simultaneously in 11 patients during a control state, during norepinephrine infusion, as well as during positive and negative ...intra-alveolar pressures. A good correlation (r = 0.95) found between the two pressures permits the use of corrected pulmonary artery-wedge pressure in calculation of pulmonary vascular resistance under control and test conditions.
Measurements of event-by-event fluctuations of the mean transverse momentum in PbAu collisions at 40, 80, and 158
A
GeV/c
are presented. A significant excess of mean
p
T
fluctuations at ...mid-rapidity is observed over the expectation from statistically independent particle emission. The results are somewhat smaller than recent measurements at RHIC. A possible non-monotonic behavior of the mean
p
T
fluctuations as function of collision energy, which may have indicated that the system has passed the critical point of the QCD phase diagram in the range of
μ
B
under investigation, has not been observed. The centrality dependence of mean
p
T
fluctuations in PbAu is consistent with an extrapolation from
pp collisions assuming that the non-statistical fluctuations scale with multiplicity. The results are compared to calculations by the
rqmd and
urqmd event generators.
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