Comments concerning the paper "Measurement of negatively charged pion spectra in inelastic p+p interactions at 20, 31, 40, 80 and 158 GeV/c" by the NA61 collaboration
New data from the NA61 collaboration on the production of negative pions in p+p interactions at beam momenta between 20 and 158 GeV/c are critically compared to available results in the same energy range. It is concluded that the NA61 data show some discrepancies with the previous results. This concerns in particular the total yields, the $p_T$ integrated rapidity distributions and the double differential cross sections.
Mid-rapidity production of $π^{\pm}$, $\rm{K}^{\pm}$ and ($\bar{\rm{p}}$)p measured by the ALICE experiment at the LHC, in Pb-Pb and inelastic pp collisions at $\sqrt{s_{\rm{NN}}}$ = 5.02 TeV, is presented. The invariant yields are measured over a wide transverse momentum ($p_{\rm{T}}$) range from hundreds of MeV/$c$ up to 20 GeV/$c$. The results in Pb-Pb collisions are presented as a function of the collision centrality, in the range 0$-$90%. The comparison of the $p_{\rm{T}}$-integrated particle ratios, i.e. proton-to-pion (p/$π$) and kaon-to-pion (K/$π$) ratios, with similar measurements in…
The yield ratios of negatively to positively charged pions ($π^-/π^+$), negatively to positively charged kaons ($K^-/K^+$), and anti-protons to protons ($\bar p/p$) produced in mid-rapidity interval in central gold-gold (Au-Au) collisions, central lead-lead (Pb-Pb) collisions, and inelastic (INEL) or non-single-diffractive (NSD) proton-proton ($pp$) collisions, as well as in forward rapidity region in INEL $pp$ collisions are analyzed in the present work. Over an energy range from a few GeV to above 10 TeV, the chemical potentials of light flavor particles (pion, kaon, and proton) and quarks (…
A set of measurements of azimuthal asymmetries in the production of pairs of identified hadrons in deep-inelastic scattering of muons on transversely polarised $^6$LiD (deuteron) and NH$_3$ (proton) targets is presented. All available data collected in the years 2002-2004 and 2007/2010 with the COMPASS spectrometer using a muon beam of 160 GeV/$c$ at the CERN SPS were analysed. The asymmetries provide access to the transversity distribution functions via a fragmentation function that in principle may be independently obtained from $e^+e^-$ annihilation data. Results are presented, discussed an…
Preliminary results for mean negatively charged pion multiplicities $\langle π^- \rangle$ using the $h^-$ method are presented for central Ar+Sc collisions at 13, 19, 30, 40, 75 and 150\textit{A} GeV/c beam momentum. The data were recorded by the NA61/SHINE detector at the CERN SPS. Starting with rapidity distributions ${dn}/{dy}$ the procedure of obtaining total multiplicities is presented. The mean number of wounded nucleons $\langle W\rangle$ extracted from the Glissando MC model is used to calculate the ratio $\langle π^- \rangle/\langle W\rangle.$ The results are compared to those from ot…
We report a new measurement of negatively charged pion directed flow $v_1$ relative to the spectator plane for Pb+Pb collisions at the beam energy 40A GeV recorded by the NA49 experiment at CERN. $v_1$ is reported as a function of rapidity and transverse momentum in different classes of collision centrality. The projectile spectator plane is estimated using transverse segmentation of the NA49 forward hadron calorimeter. The new results extend the NA49 data for $v_1$, which was previously measured only relative to the participant plane, and complement recent preliminary data by the NA61/SHINE c…
NA61/SHINE is a large acceptance fixed target experiment at the CERN SPS which studies final hadronic states in interactions between various particles and nuclei. The main topic of this contribution are preliminary results for mean negatively charged pion multiplicities $\langle π^{-} \rangle$ from central Ar+Sc and Be+Be collisions. The data were taken recently by the NA61/SHINE collaboration for a wide range of beam momenta. Measured rapidity distributions $\frac{dn}{dy}$ were extrapolated to unmeasured regions to obtain total multiplicities $\langle π^{-} \rangle$. A new scheme to calculate…
Results are presented for directed flow of negatively charged pions measured relative to the spectator plane in Pb+Pb collisions at the beam energy 40A GeV recorded by the NA49 experiment at CERN. The measure-ments were performed as a function of rapidity and transverse momentum in two classes of collision centrality. The projectile spectator symmetry plane is estimated using the transverse segmentation of the forward hadron calorimeters. Analysis details related to event selection and particle dentification are provided along with a description of the procedure used to apply corrections for t…
Beam-Target Double Spin Asymmetry A_LT in Charged Pion Production from Deep Inelastic Scattering on a Transversely Polarized He-3 Target at 1.4<Q^2<2.7 GeV^2
Rapidity-dependent transverse momentum spectra of negatively charged pions measured at different rapidities in proton-proton collisions at the Super Proton Synchrotron (SPS) at various energies within its Beam Energy Scan (BES) program are investigated by using one- and two-component standard distributions where the chemical potential and spin property of particles are implemented. The rapidity spectra are described by a double-Gaussian distribution. At the stage of kinetic freeze-out, the event patterns are structured by the scatter plots in the three-dimensional subspaces of velocity, moment…
