13 research outputs found
System size dependence of strange particle yields and spectra at sqrt(s)=17.3 GeV
Yields and spectra of strange hadrons (K+, K-, phi, Lambda and Antilambda) as
well as of charged pions were measured in near central C+C and Si+Si collisions
at 158 AGeV beam energy with the NA49 detector. Together with earlier data for
p+p, S+S and Pb+Pb reactions the system size dependence can be studied.
Relative strangeness production rises fast and saturates at about 60
participating nucleons; the net hyperon spectra show an increasing shift
towards midrapidity for larger colliding nuclei. An interpretation based on the
formation of coherent systems of increasing volume is proposed. The transverse
mass spectra can be described by a blast wave ansatz. Increasing flow velocity
is accompanied by decreasing temperatures for both kinetic and chemical freeze
out. The increasing gap between inelastic and elastic decoupling leaves space
for rescattering.Comment: 8 pages, 6 figures, Proceedings of the Hot Quarks 2004 worksho
Improved Determination of Strange Distribution Function from the Global Analysis Using BHPS Model
System size and centrality dependence of the balance function in A+A collisions at root S-NN=17.2 GeV
Electric charge correlations were studied for p+p, C+C, Si+Si, and
centrality selected Pb+Pb collisions at root s(NN) = 17.2 GeV with the
NA49 large acceptance detector at the CERN SPS. In particular,
long-range pseudorapidity correlations of oppositely charged particles
were measured using the balance function method. The width of the
balance function decreases with increasing system size and centrality of
the reactions. This decrease could be related to an increasing delay of
hadronization in central Pb+Pb collisions
System-size dependence of strangeness production in nucleus-nucleus collisions at root S-NN=17.3 GeV
Emission of pi(+/-), K+/-, phi, and Lambda was measured in near-central
C + C and Si + Si collisions at 158 AGeV beam energy. Together with
earlier data for p + p, S + S, and Pb + Pb, the system-size dependence
of relative strangeness production in nucleus-nucleus collisions is
obtained. Its fast rise and the saturation observed at about 60
participating nucleons can be understood as the onset of the formation
of coherent systems of increasing size
Omega(-) and (Omega)over-bar(+) production in central Pb+Pb collisions at 40 and 158A GeV
Results are presented on Omega production in central Pb+Pb collisions at
40 and 158A GeV beam energy. For the first time in heavy ion reactions,
rapidity distributions and total yields were measured for the sum
Omega(-)+(Omega) over bar (+) at 40A GeV and for Omega(-) and (Omega)
over bar (+) separately at 158A GeV. The yields are strongly
underpredicted by the string-hadronic UrQMD model but agree better with
predictions from hadron gas models
Boer-Mulders effect in the unpolarized pion induced Drell–Yan process at COMPASS within TMD factorization
Production of charged pions, kaons and protons at large transverse momenta in pp and Pb–Pb collisions at s
Transverse momentum spectra of pi(+/-), K-+/- and p((p) over bar) up to p(T) = 20 GeV/c at mid-rapidity in pp, peripheral (60-80%) and central (0-5%) Pb-Pb collisions at v root s(NN) = 2.76 TeV have been measured using the ALICE detector at the Large Hadron Collider. The proton-to-pion and the kaon-to-pionratios both show a distinct peak at p(T) approximate to 3 GeV/c in central Pb-Pb collisions. Below the peak, p(T) 10 GeV/c particle ratios in pp and Pb-Pb collisions are in agreement and the nuclear modification factors for pi(+/-), K-+/- and p((p) over bar) indicate that, within the systematic and statistical uncertainties, the suppression is the same. This suggests that the chemical composition of leading particles from jets in the medium is similar to that of vacuum jets
Production of charged pions, kaons and protons at large transverse momenta in pp and Pb–Pb collisions at TeV
Transverse momentum spectra of pi(+/-), K-+/- and p((p) over bar) up to p(T) = 20 GeV/c at mid-rapidity in pp, peripheral (60-80%) and central (0-5%) Pb-Pb collisions at v root s(NN) = 2.76 TeV have been measured using the ALICE detector at the Large Hadron Collider. The proton-to-pion and the kaon-to-pionratios both show a distinct peak at p(T) approximate to 3 GeV/c in central Pb-Pb collisions. Below the peak, p(T) 10 GeV/c particle ratios in pp and Pb-Pb collisions are in agreement and the nuclear modification factors for pi(+/-), K-+/- and p((p) over bar) indicate that, within the systematic and statistical uncertainties, the suppression is the same. This suggests that the chemical composition of leading particles from jets in the medium is similar to that of vacuum jets
Production of charged pions, kaons and protons at large transverse momenta in pp and Pb–Pb collisions at TeV
Transverse momentum spectra of pi(+/-), K-+/- and p((p) over bar) up to p(T) = 20 GeV/c at mid-rapidity in pp, peripheral (60-80%) and central (0-5%) Pb-Pb collisions at v root s(NN) = 2.76 TeV have been measured using the ALICE detector at the Large Hadron Collider. The proton-to-pion and the kaon-to-pionratios both show a distinct peak at p(T) approximate to 3 GeV/c in central Pb-Pb collisions. Below the peak, p(T) 10 GeV/c particle ratios in pp and Pb-Pb collisions are in agreement and the nuclear modification factors for pi(+/-), K-+/- and p((p) over bar) indicate that, within the systematic and statistical uncertainties, the suppression is the same. This suggests that the chemical composition of leading particles from jets in the medium is similar to that of vacuum jets
Multiplicity dependence of pion, kaon, proton and lambda production in p–Pb collisions at √sNN = 5.02 TeV
Inthis Letter, comprehensive results on π±,K±,K0S, p(pbar) and Λ(Λbar) production at mid-rapidity (0< yCMS < 0.5) in p–Pb collisions at √sNN = 5.02 TeV, measured by the ALICE detector at the LHC, are reported. The transverse momentum distributions exhibit a hardening as a function of event multiplicity, which is stronger for heavier particles. This behavior is similar to what has been observed in pp and Pb–Pb collisions at the LHC. The measured pT distributions are compared to d–Au, Au–Au and Pb–Pb results at lower energy and with predictions based on QCD-inspired and hydrodynamic models