B. Boimska

Measurements of charged pion and kaon production in central Pb+Pb collisions at 40, 80, and 158 A GeV are presented. These are compared with data at lower and higher energies as well as with results from p+p interactions. The mean pion multiplicity per wounded nucleon increases approximately linearly with s1/4NN with a change of slope starting in the region 15–40 A GeV. The change from pion suppression with respect to p+p interactions, as observed at low collision energies, to pion enhancement at high energies occurs at about 40A GeV. A nonmonotonic energy dependence of the ratio of K+ to π+ yields is observed, with a maximum close to 40A GeV and an indication of a nearly constant value at higher energies. The measured dependences may be related to an increase of the entropy production and a decrease of the strangeness to entropy ratio in central Pb+Pb collisions in the low SPS energy range, which is consistent with the hypothesis that a transient state of deconfined matter is created above these energies. Other interpretations of the data are also discussed.Received 6 May 2002DOI:https://doi.org/10.1103/PhysRevC.66.054902©2002 American Physical Society

Results on charged pion and kaon production in central Pb+Pb collisions at 20A and 30A GeV are presented and compared to data at lower and higher energies. A rapid change of the energy dependence is observed around 30A GeV for the yields of pions and kaons as well as for the shape of the transverse mass spectra. The change is compatible with the prediction that the threshold for production of a state of deconfined matter at the early stage of the collisions is located at low SPS energies.

Directed and elliptic flow measurements for charged pions and protons are reported as a function of transverse momentum, rapidity, and centrality for 40 and 158A GeV Pb + Pb collisions as recorded by the NA49 detector. Both the standard method of correlating particles with an event plane, and the cumulant method of studying multiparticle correlations are used. In the standard method the directed flow is corrected for conservation of momentum. In the cumulant method elliptic flow is reconstructed from genuine 4, 6, and 8-particle correlations, showing the first unequivocal evidence for collective motion in A+A collisions at SPS energies.

Results of resonance searches in the Xi(-)pi(-), Xi(-)pi(+), Xi;(+)pi(-), and Xi;(+)pi(+) invariant mass spectra in proton-proton collisions at sqrt[s]=17.2 GeV are presented. Evidence is shown for the existence of a narrow Xi(-)pi(-) baryon resonance with mass of 1.862+/-0.002 GeV/c(2) and width below the detector resolution of about 0.018 GeV/c(2). The significance is estimated to be above 4.2sigma. This state is a candidate for the hypothetical exotic Xi(--)(3/2) baryon with S=-2, I=3 / 2, and a quark content of (dsdsū). At the same mass, a peak is observed in the Xi(-)pi(+) spectrum which is a candidate for the Xi(0)(3/2) member of this isospin quartet with a quark content of (dsus[-]d). The corresponding antibaryon spectra also show enhancements at the same invariant mass.

Net proton and negative hadron spectra for central Pb+Pb collisions at 158 GeV per nucleon at the CERN Super Proton Synchrotron were measured and compared to spectra from lighter systems. Net baryon distributions were derived from those of net protons. Stopping (rapidity shift with respect to the beam) and mean transverse momentum ⟨pT⟩ of net baryons increase with system size. The rapidity density of negative hadrons scales with the number of participant nucleons for nuclear collisions, whereas their ⟨pT⟩ is independent of system size. The ⟨pT⟩ dependence upon particle mass and system size is consistent with larger transverse flow velocity at midrapidity for Pb+Pb compared to S+S central collisions.Received 22 October 1998DOI:https://doi.org/10.1103/PhysRevLett.82.2471©1999 American Physical Society

φ meson production is studied by the NA49 Collaboration in central Pb + Pb collisions at 20A, 30A, 40A, 80A, and 158A GeV beam energy.The data are compared with measurements at lower and higher energies and with microscopic and thermal models.The energy dependence of yields and spectral distributions is compatible with the assumption that partonic degrees of freedom set in at low SPS energies.

Yields and phase space distributions of φ-mesons emitted from p+p (minimum bias trigger), p+Pb (at various centralities) and central Pb+Pb collisions are reported (Ebeam=158AGeV). The decay φ→K+K− was used for identification. The φ/π ratio is found to increase by a factor of 3.0±0.7 from inelastic p+p to central Pb+Pb. Significant enhancement in this ratio is also observed in subclasses of p+p events (characterized by high charged-particle multiplicity) as well as in the forward hemisphere of central p+Pb collisions. In Pb+Pb no shift or significant broadening of the φ-peak is seen.

We present first data on event-by-event fluctuations in the average transverse momentum of charged particles produced in Pb+Pb collisions at the CERN SPS. This measurement provides previously unavailable information allowing sensitive tests of microscopic and thermodynamic collision models and to search for fluctuations expected to occur in the vicinity of the predicted QCD phase transition. We find that the observed variance of the event-by-event average transverse momentum is consistent with independent particle production modified by the known two-particle correlations due to quantum statistics and final state interactions and folded with the resolution of the NA49 apparatus. For two specific models of non-statistical fluctuations in transverse momentum limits are derived in terms of fluctuation amplitude. We show that a significant part of the parameter space for a model of isospin fluctuations predicted as a consequence of chiral symmetry restoration in a non-equilibrium scenario is excluded by our measurement.

The transverse mass m t distributions for antiprotons are measured at midrapidity for minimum bias Pb+Pb collisions at 158A GeV and for central Pb+Pb collisions at 20A, 30A, 40A, and 80A GeV beam energies in the fixed target experiment NA49 at the CERN SPS.The rapidity density dn/dy, inverse slope parameter T, and mean transverse mass m t derived from the m t distributions are studied as a function of the incident energy and the collision centrality and compared to the relevant data on proton production.The shapes of the m t distributions of p and p are very similar.The ratios of the particle yields, p/p and ¯ / p, are also analyzed.The p/p ratio exhibits an increase with decreasing centrality and a steep rise with increasing beam energy.The ¯ / p ratio increases beyond unity with decreasing beam energy.

The transverse mass m t distributions for deuterons and protons are measured in Pb+ Pb reactions near midrapidity and in the range 0 Ͻ m t -m Ͻ 1.0 ͑1.5͒ GeV/ c 2 for minimum bias collisions at 158A GeV and for central collisions at 40 and 80 A GeV beam energies.The rapidity density dn / dy, inverse slope parameter T and mean transverse mass ͗m t ͘ derived from m t distributions as well as the coalescence parameter B 2 are studied as a function of the incident energy and the collision centrality.The deuteron m t spectra are significantly harder than those of protons, especially in central collisions.The coalescence factor B 2 shows three systematic trends.First, it decreases strongly with increasing centrality reflecting an enlargement of the deuteron coalescence volume in central Pb+ Pb collisions.Second, it increases with m t .Finally, B 2 shows an increase with decreasing incident beam energy even within the SPS energy range.The results are discussed and compared to the predictions of models that include the collective expansion of the source created in Pb+ Pb collisions.

With its large acceptance and particle identification coverage the NA49 experiment (Fig. 1) can study hadron production in a wide range of high energy reactions [1]. Originally aimed at examining central Pb+Pb collisions for signatures of quark-gluon plasma formation, the scope of the experiment has been enhanced with a systematic study of impact parameter and projectile size dependence, as well as the inclusion of the more elementary p+p and p+A interactions. The question is: are predicted signals of the quark-gluon plasma observed and are there discontinuities which would support the concept of hadronic phase transition?

Results on $\Lambda$, $\bar{\Lambda}}$, $\Xi^{-}$, and $\bar{\Xi}^{+}$ production in central Pb+Pb reactions at 20A, 30A, 40A, 80A, and 158A GeV are presented. The energy dependence of transverse mass spectra, rapidity spectra, and multiplicities is discussed. Comparisons to string hadronic models (UrQMD and HSD) and statistical hadron gas models are shown. While the latter provide a reasonable description of all particle yields, the first class of models fails to match the $\Xi^{-}$, and $\bar{\Xi}^{+}$ multiplicities.

The production of charged pions in minimum bias p+C interactions is studied using a sample of 377000 inelastic events obtained with the NA49 detector at the CERN SPS at 158 GeV/c beam momentum. The data cover a phase space area ranging from 0 to 1.8 GeV/c in transverse momentum and from -0.1 to 0.5 in Feynman xF. Inclusive invariant cross sections are given on a grid of 270 bins per charge, thus offering for the first time a dense coverage of the projectile hemisphere and of the cross-over region into the target fragmentation zone.

Production of $d$, $t$, and $^3$He nuclei in central Pb+Pb interactions was studied at five collision energies ($\sqrt{s_{NN}}=$ 6.3, 7.6, 8.8, 12.3, and 17.3 GeV) with the NA49 detector at the CERN SPS. Transverse momentum spectra, rapidity distributions, and particle ratios were measured. Yields are compared to predictions of statistical models. Phase-space distributions of light nuclei are discussed and compared to those of protons in the context of a coalescence approach. The coalescence parameters $B_2$ and $B_3$, as well as coalescence radii for $d$ and $^3$He were determined as a function of transverse mass at all energies.

Production of Lambda and Antilambda hyperons was measured in central Pb-Pb collisions at 40, 80, and 158 A$\cdot$GeV beam energy on a fixed target. Transverse mass spectra and rapidity distributions are given for all three energies. The $\Lambda/\pi$ ratio at mid-rapidity and in full phase space shows a pronounced maximum between the highest AGS and 40 A$\cdot$GeV SPS energies, whereas the $\bar{\Lambda}/\pi$ ratio exhibits a monotonic increase.

Results are presented on event-by-event fluctuations in transverse momentum of charged particles, produced at forward rapidities in p+p, C+C, Si+Si and Pb+Pb collisions at 158 AGeV. Three different characteristics are discussed: the average transverse momentum of the event, the Phi_pT fluctuation measure and two-particle transverse momentum correlations. In the kinematic region explored, the dynamical fluctuations are found to be small. However, a significant system size dependence of Phi_pT is observed, with the largest value measured in peripheral Pb+Pb interactions. The data are compared with predictions of several models.

New data on the production of protons, anti-protons and neutrons in p+p interactions are presented. The data come from a sample of 4.8 million inelastic events obtained with the NA49 detector at the CERN SPS at 158 GeV/c beam momentum. The charged baryons are identified by energy loss measurement in a large TPC tracking system. Neutrons are detected in a forward hadronic calorimeter. Inclusive invariant cross sections are obtained in intervals from 0 to 1.9 GeV/c (0 to 1.5 GeV/c) in transverse momentum and from −0.05 to 0.95 (−0.05 to 0.4) in Feynman x for protons (anti-protons), respectively. p T integrated neutron cross sections are given in the interval from 0.1 to 0.9 in Feynman x. The data are compared to a wide sample of existing results in the SPS and ISR energy ranges as well as to proton and neutron measurements from HERA and RHIC.

The yields of (anti)protons were measured by the NA49 Collaboration in centrality-selected Pb $+$ Pb collisions at $40A$ and $158A$ GeV. Particle identification was obtained in the laboratory momentum range from 5 to 63 GeV$/c$ by measuring the energy loss $dE/dx$ in the time projection chamber detector gas. The corresponding rapidity coverage extends 1.6 units from midrapidity into the forward hemisphere. Transverse-mass spectra, the rapidity dependences of the average transverse mass, and rapidity density distributions were studied as a function of collision centrality. The values of the average transverse mass as well as the midrapidity yields of protons normalized to the number of wounded nucleons show only modest centrality dependences. In contrast, the shape of the rapidity distribution changes significantly with collision centrality, especially at $40A$ GeV. The experimental results are compared to calculations of the hadron-string dynamics and the ultrarelativistic quantum-molecular-dynamics transport models.

New data on the production of charged kaons in p+p interactions are presented. The data come from a sample of 4.8 million inelastic events obtained with the NA49 detector at the CERN SPS at 158 GeV/c beam momentum. The kaons are identified by energy loss in a large TPC tracking system. Inclusive invariant cross sections are obtained in intervals from 0 to 1.7 GeV/c in transverse momentum and from 0 to 0.5 in Feynman x. Using these data as a reference, a new evaluation of the energy dependence of kaon production, including neutral kaons, is conducted over a range from 3 GeV to $\mathrm{p}+\overline{\mathrm{p}}$ collider energies.

We look for fluctuations expected for the QCD critical point using an intermittency analysis in the transverse momentum phase space of protons produced around midrapidity in the 12.5 % most central C+C, Si+Si and Pb+Pb collisions at the maximum SPS energy of 158A GeV. We find evidence of power-law fluctuations for the Si+Si data. The fitted power-law exponent $$\phi _{2} = 0.96^{+0.38}_{-0.25}\text { (stat.)}$$ $$\pm $$ $$0.16\text { (syst.)}$$ is consistent with the value expected for critical fluctuations. Power-law fluctuations had previously also been observed in low-mass $$\pi ^+ \pi ^-$$ pairs in the same Si+Si collisions.

We present the first measurement of fluctuations from event to event in the production of strange particles in collisions of heavy nuclei. The ratio of charged kaons to charged pions is determined for individual central Pb+Pb collisions. After accounting for the fluctuations due to detector resolution and finite number statistics we derive an upper limit on genuine nonstatistical fluctuations, which could be related to a first- or second-order QCD phase transition. Such fluctuations are shown to be very small.

Results are presented on Omega production in central Pb+Pb collisions at 40 and 158 AGeV beam energy. Given are transverse-mass spectra, rapidity distributions, and total yields for the sum Omega+Antiomega at 40 AGeV and for Omega and Antiomega separately at 158 AGeV. The yields are strongly under-predicted by the string-hadronic UrQMD model and are in better agreement with predictions from a hadron gas models.

The energy dependence of hadron production in central Pb+Pb collisions is presented and discussed. In particular, midrapidity $m_T$-spectra for $\pi^-$, $K^-$, $K^+$, $p$, $\bar{p}$, $d$, $\phi$, $\Lambda$ and $\bar{\Lambda}$ at 40, 80 and 158 $A$GeV are shown. In addition $\Xi$ and $\Omega$ spectra are available at 158 $A$GeV. The spectra allow to determine the thermal freeze-out temperature $T$ and the transverse flow velocity $\beta_T$ at the three energies. We do not observe a significant energy dependence of these parameters; furthermore there is no indication of early thermal freeze-out of $\Xi$ and $\Omega$ at 158 $A$GeV. Rapidity spectra for $\pi^-$, $K^-$, $K^+$ and $\phi$ at 40, 80 and 158 $A$GeV are shown, as well as first results on $\Omega$ rapidity distributions at 158 $A$GeV. The chemical freeze-out parameters $T$ and $\mu_B$ at the three energies are determined from the total yields. The parameters are close to the expected phase boundary in the SPS energy range and above. Using the total yields of kaons and lambdas, the energy dependence of the strangeness to pion ratio is discussed. A maximum in this ratio is found at 40 $A$GeV. This maximum could indicate the formation of deconfined matter at energies above 40 $A$GeV. A search for open charm in a large sample of 158 $A$GeV events is presented. No signal is observed. This result is compared to several model predictions.

Results of the production of Xi and Xi-bar hyperons in central Pb+Pb interactions at 158 GeV/c per nucleon are presented. This analysis utilises a global reconstruction procedure, which allows a measurement of 4pi integrated yields to be made for the first time. Inverse slope paramters, which are determined from an exponential fit to the transverse mass spectra, are shown. Central rapidity densities are found to be 1.49 +- 0.08 and 0.33 +- 0.04 per event per unit of rapidity for Xi and Xi-bar respectively. Yields integrated to full phase space are 4.12 +- 0.02 and 0.77 +- 0.04 for Xi and Xi-bar. The ratio of Xi-bar/Xi at mid-rapidity is 0.22 +- 0.03.

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.

The centrality and system size dependence of multiplicity fluctuations of charged particles produced in nuclear collisions at $158A$ GeV was studied by the NA49 Collaboration. Centrality selected Pb+Pb collisions, semicentral C+C and Si+Si collisions as well as inelastic $p$+$p$ interactions were analyzed. The number of projectile participants determined on an event-by-event basis was used to characterize the collision centrality. The scaled variance of the multiplicity distribution obtained in the forward rapidity region ($1.1<{y}_{\mathrm{c.m.}}<2.6$) shows a significant increase toward peripheral collisions. The results are similar for negatively and positively charged particles and about 50% larger for all charged particles. String-hadronic models of nuclear reactions without the fusion process do not reproduce the rise of fluctuations from central toward peripheral collisions. The measured centrality dependence can be reproduced in superposition models with the assumption of contributions from target participants to particle production in the forward hemisphere or in string models with fusion.

Production of the $K^{\ast}(892)^0$ and $\bar{K}^{\ast}(892)^0$ resonances was studied via their $K^+ \pi^-$ and $K^- \pi^+$ decay modes in central Pb+Pb, Si+Si, C+C and inelastic p+p collisions at 158\agev ($\sqrt{s_{NN}}$ = 17.3 GeV) with the NA49 detector at the CERN SPS. Transverse momentum and rapidity distributions were measured and total yields were estimated. The yield of $K^{\ast}$ exceeds that of $\bar{K}^{\ast}$ by about a factor of two in nucleus-nucleus reactions. The total yield ratios $< K^{\ast} >/< K^+ >$ and $< \bar{K}^{\ast} >/< K^->$ are strongly suppressed in central Pb+Pb compared to p+p, C+C and Si+Si collisions in agreement with the expected attenuation of these short-lived resonance states in the hadronic phase of the expanding fireball. The UrQMD model, although incorporating such a scenario, does not provide a quantitative description of the experimental results. The statistical hadron gas model assuming the same freeze-out parameters for stable hadrons and resonances overestimates the $< K^{\ast} >/< K >$ ratios in central Pb+Pb collisions by about a factor of 2.5.

Results are presented on event-by-event electric charge fluctuations in central Pb+Pb collisions at 20, 30, 40, 80 and 158 AGeV. The observed fluctuations are close to those expected for a gas of pions correlated by global charge conservation only. These fluctuations are considerably larger than those calculated for an ideal gas of deconfined quarks and gluons. The present measurements do not necessarily exclude reduced fluctuations from a quark-gluon plasma because these might be masked by contributions from resonance decays.

New results from the energy scan programme of NA49, in particular kaon production at 30 AGeV and phi production at 40 and 80 AGeV are presented. The K+/pi+ ratio shows a pronounced maximum at 30 AGeV; the kaon slope parameters are constant at SPS energies. Both findings support the scenario of a phase transition at about 30 AGeV beam energy. The phi/pi ratio increases smoothly with beam energy, showing an energy dependence similar to K-/pi-. The measured particle yields can be reproduced by a hadron gas model, with chemical freeze-out parameters on a smooth curve in the T-muB plane. The transverse spectra can be understood as resulting from a rapidly expanding, locally equilibrated source. No evidence for an earlier kinetic decoupling of heavy hyperons is found.

In this review we first outline the basics of transport theory and its recent generalization to off-shell transport. We then present in some detail the main ingredients of any transport method using in particular the Giessen Boltzmann–Uehling–Uhlenbeck (GiBUU) implementation of this theory as an example. We discuss the potentials used, the ground state initialization and the collision term, including the in-medium modifications of the latter. The central part of this review covers applications of GiBUU to a wide class of reactions, starting from pion-induced reactions over proton and antiproton reactions on nuclei to heavy-ion collisions (up to about 30AGeV). A major part concerns also the description of photon-, electron- and neutrino-induced reactions (in the energy range from a few 100MeV to a few 100GeV). For this wide class of reactions GiBUU gives an excellent description with the same physics input and the same code being used. We argue that GiBUU is an indispensable tool for any investigation of nuclear reactions in which final-state interactions play a role. Studies of pion–nucleus interactions, nuclear fragmentation, heavy-ion reactions, hypernucleus formation, hadronization, color transparency, electron–nucleus collisions and neutrino–nucleus interactions are all possible applications of GiBUU and are discussed in this article.

Electric charge correlations were studied for p+p, C+C, Si+Si, and centrality selected Pb+Pb collisions at $\sqrt{{s}_{\mathrm{NN}}}=17.2$ 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.

Kaons and protons carry large parts of two conserved quantities, strangeness and baryon number. It is argued that their correlation and thus also fluctuations are sensitive to conditions prevailing at the anticipated parton-hadron phase boundary. Fluctuations of the $(\mathrm{K}^+ + \mathrm{K}^-)/(\mathrm{p}+\bar{\mathrm{p}})$ and $\mathrm{K}^+/\mathrm{p}$ ratios have been measured for the first time by NA49 in central Pb+Pb collisions at 5 SPS energies between $\sqrt{s_{NN}}$= 6.3 GeV and 17.3 GeV. Both ratios exhibit a change of sign in $\sigma_{\mathrm{dyn}}$, a measure of non-statistical fluctuations, around $\sqrt{s_{NN}}$ = 8 GeV. Below this energy, $\sigma_{\mathrm{dyn}}$ is positive, indicating higher fluctuation compared to a mixed event background sample, while for higher energies, $\sigma_{\mathrm{dyn}}$ is negative, indicating correlated emission of kaons and protons. The results are compared to UrQMD calculations which which give a good description at the higher SPS energies, but fail to reproduce the transition to positive values.

A novel approach, the identity method, was used for particle identification and the study of fluctuations of particle yield ratios in Pb + Pb collisions at the CERN Super Proton Synchrotron (SPS).This procedure allows one to measure the moments of the multiplicity distributions of protons (p), kaons (K), pions (π ), and electrons (e) in case of incomplete particle identification.Using these moments the excitation function of the fluctuation measure ν dyn [A,B] was measured, with A and B denoting different particle types.The obtained energy dependence of ν dyn agrees with previously published NA49 results on the related measure σ dyn .However, ν dyn [K,p] and ν dyn [K,π ] were found to depend on the phase-space coverage.This feature most likely explains the reported differences between measurements of NA49 and those of STAR in central Au + Au collisions.

New data with a minimum bias trigger for 158 GeV/nucleon Pb + Pb have been analyzed. Directed and elliptic flow as a function of rapidity of the particles and centrality of the collision are presented. The centrality dependence of the ratio of elliptic flow to the initial space elliptic anisotropy is compared to models.

The NA49 large-acceptance hadron spectrometer has measured strange and multi-strange hadrons from Pb + Pb and p + p collisions at the CERN SPS. Preliminary results for the transverse mass and rapidity distributions for Ξ- and from central Pb + Pb collisions at 158 GeV c-1/nucleon are presented. Fully integrated yields per event of 4.42 ± 0.31 and 0.74 ± 0.04 are found for Ξ- and , respectively, leading to a 4π /Ξ- ratio of 0.17 ± 0.02. The ratio /Ξ- at mid-rapidity is found to be 0.22 ± 0.04, agreeing with previously published values. In addition, preliminary data on the Λ(1520) and ϕ (1020) resonances are presented. The Λ(1520) multiplicity for p + p collisions is found to be 0.012 ± 0.003. No signal is observed for Pb + Pb collisions and a production upper limit of 1.36 Λ(1520) per event indicates an apparent suppression when comparing with scaled p + p data. Integrated ϕ(1020) yields per event are found to be 7.6 ± 1.1 for Pb + Pb and 0.012 ± 0.0015 for p + p collisions. No significant shift or broadening of the ϕ(1020) invariant mass distribution is observed in central Pb + Pb collisions.

The dependence of the K+ and K− production on the number of nucleons involved in the annihilation process is investigated experimentally in the p¯ annihilation at rest on hydrogen, deuterium, 3He and 4He gas targets. Annihilations with any number of prongs (charged pions and kaons, protons and deuterons) are analyzed. Events with and without production of neutral mesons and with and without emission of fast neutrons (that is neutrons involved in the annihilation process) are recognized. The results are consistent with our previous ones on a more restricted sample of annihilation reactions and put in evidence that the strangeness production is lower or higher depending on the reaction channel. As a general trend, the strangeness production is higher in events without neutral mesons and still higher in events with the involvement of a higher number of nucleons. Both K+ and K− productions increase with the number of involved nucleons, but K+ much more. The maximum K+ production is observed in the reaction K+2π+2π−3n on 4He (with the involvement of 3–4 nucleons); compared with the production on hydrogen in the reaction K+π+2π−, the production on 4He is higher by a factor of 31.7±5.5. In the light of some theoretical speculations, this enhancement factor is too high to be explainable in terms of hadronic interactions and could be interpreted as a signature of quark deconfinement and of formation of a quark–gluon plasma.

In this paper we present recent results from the NA49 experiment for Λ and hyperons produced in central Pb + Pb collisions at 40, 80 and 158 A GeV. Transverse mass spectra and rapidity distributions for Λ are shown for all three energies. The shape of the rapidity distribution becomes flatter with increasing beam energy. The multiplicities at mid-rapidity as well as the total yields are studied as a function of collision energy including AGS measurements. The ratio Λ/π at mid-rapidity and in 4π has a maximum around 40 A GeV. In addition, rapidity distributions have been measured at 40 and 80 A GeV, which allows us to study the /Λ ratio.

The large acceptance and high momentum resolution as well as the significant particle identification capabilities of the NA49 experiment at the CERN SPS allow for a broad study of fluctuations and correlations in hadronic interactions. In the first part recent results on event-by-event charge and p_t fluctuations are presented. Charge fluctuations in central Pb+Pb reactions are investigated at three different beam energies (40, 80, and 158 AGeV), while for the p_t fluctuations the focus is put on the system size dependence at 158 AGeV. In the second part recent results on Bose Einstein correlations of h-h- pairs in minimum bias Pb+Pb reactions at 40 and 158 AGeV, as well as of K+K+ and K-K- pairs in central Pb+Pb collisions at 158 AGeV are shown. Additionally, other types of two particle correlations, namely pi p, Lambda p, and Lambda Lambda correlations, have been measured by the NA49 experiment. Finally, results on the energy and system size dependence of deuteron coalescence are discussed.

Results from the NA49 experiment at the CERN SPS are presented on event-by-event transverse momentum and multiplicity fluctuations of charged particles, produced at forward rapidities in central Pb+Pb interactions at beam momenta 20$A$, 30$A$, 40$A$, 80$A$, and 158$A$ GeV/c, as well as in systems of different size ($p+p$, C+C, Si+Si, and Pb+Pb) at 158$A$ GeV/c. This publication extends the previous NA49 measurements of the strongly intensive measure $\Phi_{p_T}$ by a study of the recently proposed strongly intensive measures of fluctuations $\Delta[P_T, N]$ and $\Sigma[P_T, N]$. In the explored kinematic region transverse momentum and multiplicity fluctuations show no significant energy dependence in the SPS energy range. However, a remarkable system size dependence is observed for both $\Delta[P_T, N]$ and $\Sigma[P_T, N]$, with the largest values measured in peripheral Pb+Pb interactions. The results are compared with NA61/SHINE measurements in $p+p$ collisions, as well as with predictions of the UrQMD and EPOS models.

Results from electric charge correlations studied with the Balance Function (BF) method in $A+A$ collisions from $20A$ to $158A$ GeV are presented in two different rapidity intervals: In the midrapidity region we observe a decrease of the width of the BF distribution with increasing centrality of the collision, whereas this effect vanishes in the forward rapidity region. Results from the energy dependence study in central $\mathrm{Pb}+\mathrm{Pb}$ collisions show that the narrowing of the BF expressed by the normalized width parameter $W$ increases with energy toward the highest CERN Super Proton Synchrotron and BNL Relativistic Heavy Ion Collider energies. Finally we compare our experimental data points with the predictions of several models. The hadronic string models Ultra-relativistic Quantum Molecular Dynamics and Heavy Ion Jet INteraction Generator (HIJING) do not reproduce the observed narrowing of the BF. However, A MultiPhase Transport medel (AMPT), which contains a quark-parton transport phase before hadronization, can reproduce the narrowing of the BF's width with centrality. This confirms the proposed sensitivity of the BF analysis to the time of hadronization.

Experimental results on deuteron emission from central Pb+Pb collisions (Ebeam=158A GeV, fixed target), obtained by NA49 at the CERN SPS accelerator, are presented. The transverse mass mt distribution was measured near mid-rapidity (2.0<y<2.5) in the range of 0<mt−m0<0.9 GeV/c2 (0<pt<2.0 GeV/c) for the 4% most central collisions. An exponential fit gives an inverse slope Td=(450±30) MeV and a yield dNd/dy=0.34±0.03. The coalescence factor B2(mt=m0)=(3.5±1.0)·10−4 GeV2 and its mt-dependence are determined and discussed in terms of a model that includes the collective expansion of the source created in a collision. The derived Gaussian size parameter RG of the emission volume is consistent with earlier HBT results on the source of pion emission.

The two-proton correlation function at midrapidity from Pb+Pb central collisions at 158 A GeV has been measured by the NA49 experiment. The results are compared to model predictions from static thermal Gaussian proton source distributions and transport models rqmd and venus. An effective proton source size is determined by minimizing χ2/ndf between the correlation functions of the data and those calculated for the Gaussian sources, yielding σeff=3.85±0.15(stat.)+0.60−0.25(syst.) fm. Both the rqmd and the venus model are consistent with the data within the error in the correlation peak region.

Bose-Einstein correlations of charged kaons were measured near mid-rapidity in central Pb+Pb collisions at 158 A$\cdot$GeV by the NA49 experiment at the CERN SPS. Source radii were extracted using the Yano-Koonin-Podgoretsky and Bertsch-Pratt parameterizations. The results are compared to published pion data. The measured $m_\perp$ dependence for kaons and pions is consistent with collective transverse expansion of the source and a freeze-out time of about 9.5 $fm$.

New measurements by the NA49 experiment of the centrality dependence of event-by-event fluctuations of the particle yield ratios $({K}^{+}+{K}^{\ensuremath{-}})/({\ensuremath{\pi}}^{+}+{\ensuremath{\pi}}^{\ensuremath{-}})$, $(p+\overline{p})/({\ensuremath{\pi}}^{+}+{\ensuremath{\pi}}^{\ensuremath{-}})$, and $({K}^{+}+{K}^{\ensuremath{-}})/(p+\overline{p})$ are presented for Pb+Pb collisions at 158$A$ GeV. The absolute values of the dynamical fluctuations of these ratios, quantified by the measure ${\ensuremath{\sigma}}_{\text{dyn}}$, increase by about a factor of two from central to semiperipheral collisions. Multiplicity scaling scenarios are tested and found to apply for both the centrality and the previously published energy dependence of the $({K}^{+}+{K}^{\ensuremath{-}})/({\ensuremath{\pi}}^{+}+{\ensuremath{\pi}}^{\ensuremath{-}})$ and $(p+\overline{p})/({\ensuremath{\pi}}^{+}+{\ensuremath{\pi}}^{\ensuremath{-}})$ ratio fluctuations. A description of the centrality and energy dependence of $({K}^{+}+{K}^{\ensuremath{-}})/(p+\overline{p})$ ratio fluctuations by a common scaling prescription is not possible since there is a sign change in the energy dependence.

Source imaging methodology is used to provide a three-dimensional two-pion source function for mid-rapidity pion pairs with $p_T<70$ MeV/c in central ($0-7%$) Pb+Pb collisions at $\sqrt s_{NN}$=17.3 GeV. Prominent non-Gaussian tails are observed in the pion pair transverse momentum (outward) and in the beam (longitudinal) directions. Model calculations reproduce them with the assumption of Bjorken longitudinal boost invariance and transverse flow blast-wave dynamics coupled with "outside-in burning" in the transverse direction; they also yield a proper time for breakup and emission duration for the pion source.

We describe the construction, test and installation procedures, and the experience gained with the operation of a small but complete system of high-rate Micro-Strip Gas Chambers, made on thin borosilicate glass with a diamond-like coating with chromium or gold strips. A set of detectors, fully equipped with read-out electronics and each with an active area of 100 × 100 mm2, was exposed during six months to a high-intensity muon beam at CERN with a peak intensity of ∼ 104 mm−2s−1. Continuous monitoring of the performance of the chambers during the beam runs allowed the evaluation of detection efficiency and the monitoring of accidental rates, as well as the study of ambient induced variations and aging in realistic beam conditions. No significant difference has been found in the operation of under-and over-coated plates. Efficiencies could reach ∼ 98% in best operating conditions, although local lower values were often observed due to missing channels (open strips, broken bonds and dead electronic channels). The long-term operation of the chambers has been more difficult than expected, with the appearance of break-downs and loss of efficiency in some detectors, possibly induced by the presence of small gas leaks, to water permeation or to residual reactivity of the quencher gas (dimethylether).

The CMS experiment comprises MSGCs as one of the key detection elements for high luminosity tracking at LHC. In _addition to the high dose rate of 10 mC/year per cm of strip, these detectors have to survive the hostile presence of highly ionizing particles, neutrons low energy gammas and hadrons. In this report we present the results of systematic tests on maximum safe operational gain limits in MSGCs before the discharge. Long term ageing tests performed on prototype open ‘banana’ modules envisaged to be arranged around the interaction region in the forward part of the CMS tracker show no evidence of gain drop up to equivalent ∼ 10 years of LHC operation. A comparison is made between argon and neon gas mixtures with DME in equal proportions by investigating long term irradiation effocts on chamber operation by introducing controlled and reproducible pollution in the gas lines.

We look for fluctuations expected for the QCD critical point using an intermittency analysis in the transverse momentum phase space of protons produced around midrapidity in the 12.5\% most central C+C, Si+Si and Pb+Pb collisions at the maximum SPS energy of 158$A$~GeV. We find evidence of power-law fluctuations for the Si+Si data. The fitted power-law exponent $\phi_{2} = 0.96^{+0.38}_{-0.25}\text{ (stat.)}$ $\pm 0.16\text{ (syst.)}$ is consistent with the va\-lue expected for critical fluctuations. Power-law fluctuations had previously also been observed in low-mass $\pi^+ \pi^-$ pairs in the same Si+Si collisions.

Results are presented from a search for the decays D0 -> Kmin piplus and D0bar -> Kplus pimin in a sample of 3.8x10^6 central Pb-Pb events collected with a beam energy of 158A GeV by NA49 at the CERN SPS. No signal is observed. An upper limit on D0 production is derived and compared to predictions from several models.

Differential elliptic flow spectra v2(pT) of π−, KS0, p, Λ have been measured at sNN=17.3GeV around midrapidity by the CERN-CERES/NA45 experiment in mid-central Pb + Au collisions (10% of σgeo). The pT range extends from about 0.1 GeV/c (0.55 GeV/c for Λ) to more than 2 GeV/c. Protons below 0.4 GeV/c are directly identified by dE/dx. At higher pT, proton elliptic flow is derived as a constituent, besides π+ and K+, of the elliptic flow of positive pion candidates. This retrieval requires additional inputs: (i) of the particle composition, and (ii) of v2(pT) of positive pions. For (i), particle ratios obtained by NA49 are adapted to CERES conditions; for (ii), the measured v2(pT) of negative pions is substituted, assuming π+ and π− elliptic flow magnitudes to be sufficiently close. The v2(pT) spectra are compared to ideal-hydrodynamics calculations. In synopsis of the series π−–KS0–p–Λ, flow magnitudes are seen to fall with decreasing pT progressively even below hydro calculations with early kinetic freeze-out (Tf=160MeV) leaving not much time for hadronic evolution. The proton v2(pT) data show a downward swing towards low pT with excursions into negative v2 values. The pion-flow isospin asymmetry observed recently by STAR at RHIC, invalidating in principle our working assumption, is found in its impact on proton flow bracketed from above by the direct proton flow data, and not to alter any of our conclusions. Results are discussed in perspective of recent viscous hydrodynamics studies which focus on late hadronic stages.

The study of central collisions of heavy nuclei at CERN SPS energies by NA49 provided evidence for the onset of deconfinement around 30A GeV. Theoretical considerations predict a critical point of strongly interacting matter accessible in the SPS energy range. A search for the expected fluctuations has not yet found convincing signals. The strategy and plans for the continuation of this program at the SPS by NA61 with lighter nuclei is discussed.

We describe recent observations and measurements with Micro-Strip Gas Chambers coated, after manufacturing, with a thin diamond-like layer in order to increase their rate capability. Compared to the more widely used solution consisting in coating the insulating support with a conductive layer before photo-lithography (the so-called undercoating), over-coating has the advantage of avoiding possible problems with adherence of metals to the layer, damages during the etching process and reduced quality of the artwork resulting from imperfections or dust inclusions in the layer. Early tests have however indicated that, possibly because of damages to the layer due to electron and ion bombardment during the avalanche process, irreversible structural modifications and fatal breakdown could be encountered at very high integral radiation fluxes. The present paper summarizes these results, and describes recent developments demonstrating that a better choice of the parameters of the over-coat may allow to withstand the radiation doses anticipated for LHC detectors with the intrinsically simpler over-coating solution. We discuss also several possible applications of the use of thin, controlled resistivity layers for other families of detectors used or in development for CERN's high luminosity collider.

We describe recent measurements carried out in well controlled and reproducible conditions to help understanding the factors affecting the short- and long-term behaviour of Microstrip Gas Chambers. Special care has been taken concerning the gas purity and choice of materials used in the system and for the detectors construction. Detectors built on glasses with surface resistivity in the range 1013–1015 Ω/□ have shown satisfactory performance as they do not show charging-up process at high rate and stand the large doses required for the future high luminosity experiments (∼10 mC-cm−1.yr−1). Concerning the lifetime measurements, it has been observed that chambers manufactured on high-resistivity glass are far more susceptible of suffering ageing than detectors made on low resistivity, electron-conducting supports, independently of the metal used for the artwork (chromium or gold) at least in clean gas conditions. The successfully operation in the laboratory of detectors manufactured on diamond-coated glass with a surface resistivity around 1015 Ω/□ confirms the last statement. Results from a long-term, high rate beam test are also reported.

Experiment NA49 at the CERN SPS uses a large acceptance detector for a systematic study of particle yields and correlations in nucleus-nucleus, nucleon-nucleus and nucleon-nucleon collisions. Preliminary results for Pb+Pb collisions at 40, 80 and 158 A⋅GeV beam energy shown and compared to measurements at lower and higher energies.

A novel approach, the identity method, was used for particle identification and the study of fluctuations of particle yield ratios in Pb+Pb collisions at the CERN Super Proton Synchrotron (SPS). This procedure allows to unfold the moments of the unknown multiplicity distributions of protons (p), kaons (K), pions (π) and electrons (e). Using these moments the excitation function of the fluctuation measure ν\text{;dyn};[A, B] was measured, with A and B denoting different particle types. The obtained energy dependence of νdyn agrees with previously published NA49 results on the related measure σdyn. Moreover, νdyn was found to depend on the phase space coverage for [K, p] and [K, π] pairs. This feature most likely explains the reported differences between measurements of NA49 and those of STAR in central Au+Au collisions.

Results on two-particle correlations, deuteron production, event anisotropy and event-by-event fluctuations of 〈pT〉 and K/π were obtained by the NA49 experiment in Pb+Pb collisions at 158 A·GeV beam energy. The interpretation of the measurements is discussed in light of the search for deconfinement.

We describe recent developments on diamond-like carbon (DLC) over-coated Microstrip Gas Chambers made on boro-silicate drawn glass substrates. MSGC surface coating with thin DLC layer of stable and controlled resistivity was proposed to overcome the limitation of detector operation due to surface charging-up under avalanches. This brings also advantages for the detector manufacturing technology. The thin layer, deposited on top of a manufactured MSGC (over-coating), demonstrates excellent mechanical properties and very good stability. We report on recent measurements with DLC over-coated MSGCs of various surface resistivities (ranging from 101Ω/□ to 1016 Ω/□ on D-263 and AF45 glass substrates. Over-coated MSGCs with resistivity of the surface around 1015Ω/□ exhibit a stable charge gain up to radiation rates in excess of 106 Hz/mm2. Stable long-term operation up to 50 mC/cm of accumulated charge from avalanches has been demonstrated.

The latest NA49 results on event-by-event transverse momentum fluctuations are presented for central Pb+Pb interactions over the whole SPS energy range (20A - 158A GeV). Two different methods are applied: evaluating the $Φ_{p_{T}}$ fluctuation measure and studying two-particle transverse momentum correlations. The obtained results are compared to predictions of the UrQMD model. The results on the energy dependence are compared to the NA49 data on the system size dependence. The NA61 (SHINE, NA49-future) strategy of searching of the QCD critical end-point is also discussed.

We describe recent observations and measurements realized with microstrip gas chambers (MSGCs) manufactured on borosilicate glass coated with a thin layer of diamond-like carbon (DLC) having a surface resistivity around 4 × 1016 Ω/▭. The role of the back-plane electrode configuration and potential in the detector performance has been studied. Even for this very high resistivity of the coatings, MSGCs operate differently from those manufactured on bare boro-silicate glass; the charge gain increases with the radiation flux for counting rates above 103 Hz/mm2, reaching a value 60% higher for 105 Hz/mm2. This behavior does not depend on the presence and potential of the back-plane electrode; however, both maximum gain and rate capability are influenced by the drift field. From this study, compared with measurements realized previously with other detectors, we deduce that for stable high rate operation of MSGCs the resistivity of the coating should not exceed ∼1015 Ω/▭.

An overview of selected results on jet physics in heavy-ion collisions from the Compact Muon Solenoid experiment at the LHC accelerator is presented. The results were obtained for lead-lead, proton-lead and proton-proton collisions collected in the years 2010 - 2013. The jet-quenching phenomenon was studied by looking at the production of so-called “hard probes”, that is high transverse momentum charged particles, prompt photons, <i>Z</i> and <i>W</i> bosons, and jets.

The accelerating expansion of the Universe points to a small positive vacuum energy density and negative vacuum pressure.A strong candidate is the cosmological constant in Einstein's equations of General Relativity.The vacuum dark energy density extracted from astrophysics is 10 56 times smaller than the value expected from the Higgs potential in Standard Model particle physics.The dark energy scale is however close to the range of possible values expected for the light neutrino mass.We investigate this physics in a simple toy model where the chirality of the neutrino is treated by analogy as an Ising-like "spin" degree of freedom.

We look for fluctuations expected for the QCD critical point using an intermittency analysis in the transverse momentum phase space of protons produced around midrapidity in the 12.5\% most central C+C, Si+Si and Pb+Pb collisions at the maximum SPS energy of 158$A$~GeV. We find evidence of power-law fluctuations for the Si+Si data. The fitted power-law exponent $\phi_{2} = 0.96^{+0.38}_{-0.25}\text{ (stat.)}$ $\pm 0.16\text{ (syst.)}$ is consistent with the va\-lue expected for critical fluctuations. Power-law fluctuations had previously also been observed in low-mass $\pi^+ \pi^-$ pairs in the same Si+Si collisions.

Selected experimental results related to heavy-ion physics, obtained using the Compact Muon Solenoid (CMS) detector at the Large Hadron Collider (LHC), are presented.Measurements have been performed for lead-lead (PbPb), proton-lead (pPb) and proton-proton (pp) data samples collected in the years 2010-2012.The jet-quenching phenomenon has been studied by looking at the production of the so-called "hard probes", such as high transverse momentum charged particles, isolated photons, Z and W bosons, and jets.In addition, the suppression of quarkonium states and long-range two-particle correlations have been investigated.

A good understanding of different effects in particle production from nuclear collisions at LHC will require, first, understanding of the data at lower energies -in particular, these measured at SPS and RHIC energies.In this work, results on particle multiplicities and transverse momentum spectra are reported.It is known from the past studies, that particle multiplicities from high energy nuclear collisions can be parametrized and/or explained within participant ("wounded") nucleon or quark frameworks.Examples illustrating successes and failures of these two approaches are discussed.The latest results on identified particle production from the NA49 experiment at the CERN-SPS accelerator are shown.The study was done for both the nucleon and quark participant frameworks using the nuclear overlap model.In addition, results concerning transverse momentum spectra, expressed in terms of a so-called nuclear modification factor, of particles from hadron-nucleus collisions are presented.In the forward region at RHIC, particle production is suppressed -the effect often interpreted as a manifestation of saturation and/or Color Glass Condensate.Preliminary results for the SPS energy show a similar suppression, as presented and discussed in this work.

Concepts of wounded nucleon and quark participants have been used for years to parametrize and/or to explain many features of high energy nuclear collisions. Some results illustrating successes and failures of these two approaches are presented, including the latest developments. In particular, results on identified particle production from nuclear collisions measured by the NA49 experiment at the CERN-SPS are shown. The study has been done for both the nucleon and the constituent quark frameworks using the nuclear overlap model. In addition, some preliminary observations concerning the behavior of pT spectra at forward rapidities, expressed in terms of the nuclear modification factor, for hadron-nucleus collisions at the SPS energy are also presented. These results are in relevance to RHIC results for deuteron-gold collisions often interpreted as a manifestation of saturation and/or color glass condensate.

Phi meson production is studied by the NA49 Collaboration in central Pb+Pb collisions at 20A, 30A, 40A, 80A and 158A GeV beam energy. The data are compared with measurements at lower and higher energies and to microscopic and thermal models. The energy dependence of yields and spectral distributions is compatible with the assumption that partonic degrees of freedom set in at low SPS energies.

The energy dependence of multiplicity fluctuations was studied for the most central Pb + Pb collisions at 20A, 30A, 40A, 80A and 158A GeV by the NA49 experiment at the CERN SPS.The multiplicity distribution for negatively and positively charged hadrons is significantly narrower than Poisson one for all energies.No significant structure in energy dependence of the scaled variance of multiplicity fluctuations is observed.The measured scaled variance is lower than the one predicted by the grand-canonical formulation of the hadron-resonance gas model.The results for scaled variance are in approximate agreement with the string-hadronic model UrQMD.

The NA49 experiment has collected comprehensive data on particle production in nucleus-nucleus collisions over the whole SPS beam energies range, the critical energy domain where the expected phase transition to a deconfined phase is expected to occur. The latest results from Pb+Pb collisions between 20$A$ GeV and 158$A$ GeV on baryon stopping and light nuclei production as well as those for strange hyperons are presented. The measured data on $p$, $\bar{p}$, $\Lambda$, $\bar{\Lambda}$, $\Xi^-$ and $\bar{\Xi}^+$ production were used to evaluate the rapidity distributions of net-baryons at SPS energies and to compare with the results from the AGS and the RHIC for central Pb+Pb (Au+Au) collisions. The dependence of the yield ratios and the inverse slope parameter of the $m_t$ spectra on the collision energy and centrality, and the mass number of the produced nuclei $^3He$, $t$, $d$ and $\bar{d}$ are discussed within coalescence and statistical approaches. Analysis of the total multiplicity exhibits remarkable agreement between the measured yield for $^3He$ and those predicted by the statistical hadronization model. In addition, new results on $\Lambda$ and $\bar{\Lambda}$ as well as $\Xi^-$ production in minimum bias Pb+Pb reactions at 40$A$ GeV and 158$A$ GeV and central C+C, Si+Si and Pb+Pb collisions are presented. The system size dependence of the yields of these hyperons was analysed to determine the evolution of strangeness enhancement relative to elementary p+p collisions.

C. Alt9, T. Anticic23, B. Baatar8,D. Barna4, J. Bartke6, L. Betev10, H. Bialkowska20, C. Blume9, B. Boimska20, M. Botje1, J. Bracinik3, R. Bramm9, P. Buncic10, V. Cerny3, P. Christakoglou2, P. Chung19, O. Chvala14, J.G. Cramer16, P. Csato4, P. Dinkelaker9, V. Eckardt13, D. Flierl9, Z. Fodor4, P. Foka7, V. Friese7, J. Gal4, M. Gaździcki9,11, V. Genchev18, G. Georgopoulos2, E. Gladysz6, K. Grebieszkow22, S. Hegyi4, C. Hohne7, K. Kadija23, A. Karev13, D. Kikola22, M. Kliemant9, S. Kniege9, V.I. Kolesnikov8, E. Kornas6, R. Korus11, M. Kowalski6, I. Kraus7, M. Kreps3, A. Laszlo4, R. Lacey19, M. van Leeuwen1, P. Levai4, L. Litov17, B. Lungwitz9, M. Makariev17, A.I. Malakhov8, M. Mateev17, G.L. Melkumov8, A. Mischke1, M. Mitrovski9, J. Molnar4, St. Mrowczynski11, V. Nicolic23, G. Palla4, A.D. Panagiotou2, D. Panayotov17, A. Petridis2, W. Peryt22, M. Pikna3, J. Pluta22, D. Prindle16, F. Puhlhofer12, R. Renfordt9, C. Roland5, G. Roland5, M. Rybczynski11, A. Rybicki6,10, A. Sandoval7, N. Schmitz13, T. Schuster9, P. Seyboth13, F. Sikler4, B. Sitar3, E. Skrzypczak21, M. Slodkowski22, G. Stefanek11, R. Stock9, C. Strabel9, H. Strobele9, T. Susa23, I. Szentpetery4, J. Sziklai4, M. Szuba22, P. Szymanski10,20, V. Trubnikov20, D. Varga4,10, M. Vassiliou2, G.I. Veres4,5, G. Vesztergombi4, D. Vranic7, A. Wetzler9, Z. Wlodarczyk11, A. Wojtaszek11, I.K. Yoo15, J. Zimanyi4