Results on $\phi$ meson production in inelastic p+p collisions at CERN SPS energies are presented. They are derived from data collected by the NA61/SHINE fixed target experiment, by means of invariant mass spectra fits in the $\phi \to K^+K^-$ decay channel. They include the first ever measured double differential spectra of $\phi$ mesons as a function of rapidity $y$ and transverse momentum $p_T$ for proton beam momenta of 80 GeV/c and 158 GeV/c, as well as single differential spectra of $y$ or $p_T$ for beam momentum of 40 GeV/c. The corresponding total $\phi$ yields per inelastic p+p event are obtained. These results are compared with existing data on $\phi$ meson production in p+p collisions. The comparison shows consistency but superior accuracy of the present measurements. The emission of $\phi$ mesons in p+p reactions is confronted with that occurring in Pb+Pb collisions, and the experimental results are compared with model predictions. It appears that none of the considered models can properly describe all the experimental observables.
Double differential multiplicity of $\phi$ mesons produced in minimum bias p+p collisions at beam momentum of 158 GeV/c, as a function of transverse momentum $p_T$ and rapidity $y$.
Double differential multiplicity of $\phi$ mesons produced in minimum bias p+p collisions at beam momentum of 80 GeV/c, as a function of transverse momentum $p_T$ and rapidity $y$.
Transverse momentum $p_T$ spectrum of $\phi$ mesons produced in minimum bias p+p collisions at beam momentum of 40 GeV/c, in a broad rapidity $y$ bin of (0, 1.5).
Inclusive production of $\Lambda$-hyperons was measured with the large acceptance NA61/SHINE spectrometer at the CERN SPS in inelastic p+p interactions at beam momentum of 158~\GeVc. Spectra of transverse momentum and transverse mass as well as distributions of rapidity and x$_{_F}$ are presented. The mean multiplicity was estimated to be $0.120\,\pm0.006\;(stat.)\,\pm 0.010\;(sys.)$. The results are compared with previous measurements and predictions of the EPOS, UrQMD and FRITIOF models.
Double-differential yield $\frac{d^2n}{dydp_{_T}}$.
Double-differential yield $\frac{d^2n}{dydm_{_T}}$.
Double-differential yields, $\frac{d^{2}n}{x_{_F}p_{_T}}$ and $f_n(x_{_F},p_{T})$, for $x_{_F}<0$.
We present experimental results on inclusive spectra and mean multiplicities of negatively charged pions produced in inelastic p+p interactions at incident projectile momenta of 20, 31, 40, 80 and 158 GeV/c ($\sqrt{s} = $ 6.3, 7.7, 8.8, 12.3 and 17.3 GeV, respectively). The measurements were performed using the large acceptance NA61/SHINE hadron spectrometer at the CERN Super Proton Synchrotron. Two-dimensional spectra are determined in terms of rapidity and transverse momentum. Their properties such as the width of rapidity distributions and the inverse slope parameter of transverse mass spectra are extracted and their collision energy dependences are presented. The results on inelastic p+p interactions are compared with the corresponding data on central Pb+Pb collisions measured by the NA49 experiment at the CERN SPS. The results presented in this paper are part of the NA61/SHINE ion program devoted to the study of the properties of the onset of deconfinement and search for the critical point of strongly interacting matter. They are required for interpretation of results on nucleus-nucleus and proton-nucleus collisions.
Transverse momentum spectra of $\pi^-$ mesons produced in inelastic $p p$ interactions at 20 GeV in various rapidity ranges.
Transverse momentum spectra of $\pi^-$ mesons produced in inelastic $p p$ interactions at 20 GeV in various rapidity ranges.
Transverse momentum spectra of $\pi^-$ mesons produced in inelastic $p p$ interactions at 20 GeV in various rapidity ranges.
The ALICE collaboration reports the measurement of the inclusive J/psi yield as a function of charged particle pseudorapidity density dN_{ch}/deta in pp collisions at sqrt{s} = 7 TeV at the LHC. J/psi particles are detected for p_t > 0, in the rapidity interval |y| < 0.9 via decay into e+e-, and in the interval 2.5 < y < 4.0 via decay into mu+mu- pairs. An approximately linear increase of the J/psi yields normalized to their event average (dN_{J/psi}/dy)/<dN_{J/psi}/dy> with (dN_{ch}/deta)/<dN_{ch}/deta> is observed in both rapidity ranges, where dN_{ch}/deta is measured within |eta| < 1 and p_t > 0. In the highest multiplicity interval with <dN_{ch}/deta(bin)> = 24.1, corresponding to four times the minimum bias multiplicity density, an enhancement relative to the minimum bias J/psi yield by a factor of about 5 at 2.5 < y < 4 (8 at |y| < 0.9) is observed.
The relative J/psi yield (dN_(j/psi)/dy)/<dN_(j/psi)/dy> in the di-electron channel as a function of the relative charged particle multiplicity density (dN_(ch)/deta)/<dN_(ch)/deta>.
The relative J/psi yield (dN_(j/psi)/dy)/<dN_(j/psi)/dy> in the di-muon channel as a function of the relative charged particle multiplicity density (dN_(ch)/deta)/<dN_(ch)/deta>.
Dijet angular distributions from the first LHC pp collisions at center-of-mass energy sqrt(s) = 7 TeV have been measured with the ATLAS detector. The dataset used for this analysis represents an integrated luminosity of 3.1 pb-1. Dijet $\chi$ distributions and centrality ratios have been measured up to dijet masses of 2.8 TeV, and found to be in good agreement with Standard Model predictions. Analysis of the $\chi$ distributions excludes quark contact interactions with a compositeness scale $\Lambda$ below 3.4 TeV, at 95% confidence level, significantly exceeding previous limits.
CHI distribution for mass bin 340 to 520 GeV.
CHI distribution for mass bin 520 to 800 GeV.
CHI distribution for mass bin 800 to 1200 GeV.
Invariant pT spectra and rapidity densities covering a large rapidity range(-0.1 < y < 3.5) are presented for $\pi^{\pm}$ and $K^{\pm}$ mesons from central Au+Au collisions at $\sqrt{s_{NN}}$ = 62.4 GeV. The mid-rapidity yields of meson particles relative to their anti-particles are found to be close to unity ($\pi^-/\pi^+ \sim 1$, $K^-/K^+ \sim 0.85$) while the anti-proton to proton ratio is $\bar{p}/p \sim 0.49$. The rapidity dependence of the $\pi^-/\pi^+$ ratio is consistent with a small increase towards forward rapidities while the $K^-/K^+$ and $\bar{p}/p$ ratios show a steep decrease to $\sim$ 0.3 for kaons and 0.022 for protons at $y\sim 3$. It is observed that the kaon production relative to its own anti-particle as well as to pion production in wide rapidity and energy ranges shows an apparent universal behavior consistent with the baryo-chemical potential, as deduced from the $\bar{p}/p$ ratio, being the driving parameter.
$\frac{1}{2\pi p_{\mathrm{T}}}\frac{\mathrm{d}^2N}{\mathrm{d}p_{\mathrm{T}}\mathrm{d}y}$ versus $p_{\mathrm{T}}$ for $\mathrm{\pi}^{+}$ in $\mathrm{Au}-\mathrm{Au}$ at $\sqrt{s_{\mathrm{NN}}}=62.4\,\mathrm{Ge\!V}$ near $y=-0.2-0.0$ for $0-10$% central
$\frac{1}{2\pi p_{\mathrm{T}}}\frac{\mathrm{d}^2N}{\mathrm{d}p_{\mathrm{T}}\mathrm{d}y}$ versus $p_{\mathrm{T}}$ for $\mathrm{\pi}^{+}$ in $\mathrm{Au}-\mathrm{Au}$ at $\sqrt{s_{\mathrm{NN}}}=62.4\,\mathrm{Ge\!V}$ near $y=0.0-0.2$ for $0-10$% central
$\frac{1}{2\pi p_{\mathrm{T}}}\frac{\mathrm{d}^2N}{\mathrm{d}p_{\mathrm{T}}\mathrm{d}y}$ versus $p_{\mathrm{T}}$ for $\mathrm{\pi}^{+}$ in $\mathrm{Au}-\mathrm{Au}$ at $\sqrt{s_{\mathrm{NN}}}=62.4\,\mathrm{Ge\!V}$ near $y=0.7-0.9$ for $0-10$% central
Transverse momentum spectra of protons and anti-protons measured in the rapidity range 0<y<3.1 from 0-10% central Au+Au collisions at sqrt{s_{NN}}=62.4 GeV are presented. The rapidity densities, dN/dy, of protons, anti-protons and net-protons N()p-N(pbar) have been deduced from the spectra over a rapidity range wide enough to observe the expected maximum net-baryon density. From mid-rapidity to y=1 the net-proton yield is roughly constant (dN/dy ~ 10),but rises to dN/dy ~25 at 2.3<y<3.1. The mean rapidity loss is 2.01 +-0.16 units from beam rapidity. The measured rapidity distributions are compared to model predictions. Systematics of net-baryon distributions and rapidity loss vs. collision energy are discussed.
$\frac{1}{2\pi p_{\mathrm{T}}}\frac{\mathrm{d}^2N}{\mathrm{d}p_{\mathrm{T}}\mathrm{d}y}$ versus $p_{\mathrm{T}}$ for $\mathrm{p}$ in $\mathrm{Au}-\mathrm{Au}$ at $\sqrt{s_{\mathrm{NN}}}=62.4\,\mathrm{Ge\!V}$ near $y=-0.1-0.1$
$\frac{1}{2\pi p_{\mathrm{T}}}\frac{\mathrm{d}^2N}{\mathrm{d}p_{\mathrm{T}}\mathrm{d}y}$ versus $p_{\mathrm{T}}$ for $\overline{\mathrm{p}}$ in $\mathrm{Au}-\mathrm{Au}$ at $\sqrt{s_{\mathrm{NN}}}=62.4\,\mathrm{Ge\!V}$ near $y=-0.1-0.1$
$\frac{1}{2\pi p_{\mathrm{T}}}\frac{\mathrm{d}^2N}{\mathrm{d}p_{\mathrm{T}}\mathrm{d}y}$ versus $p_{\mathrm{T}}$ for $\mathrm{p}$ in $\mathrm{Au}-\mathrm{Au}$ at $\sqrt{s_{\mathrm{NN}}}=62.4\,\mathrm{Ge\!V}$ near $y=0.4-0.9$
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 to 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.
PHI transverse momentum spectra at incident energy 20 GeV/nucleon integrated over the rapidity range 0 to 1.8.
PHI transverse momentum spectra at incident energy 30 GeV/nucleon integrated over the rapidity range 0 to 1.8.
PHI transverse momentum spectra at incident energy 40 GeV/nucleon integrated over the rapidity range 0 to 1.5.
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.
Transverse mass spectra for pion production in the central rapidity region for collisions at 20 GeV per nucleon.
Transverse mass spectra for pion production in the central rapidity region for collisions at 30 GeV per nucleon.
Transverse mass spectra for kaon production in the central rapidity region for collisions at 20 GeV per nucleon.
New results on the production of charged pions 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. Pions are identified by energy loss measurement in a large TPC tracking system which covers a major fraction of the production phase space. Inclusive invariant cross sections are given on a grid of nearly 300 bins per charge over intervals from 0 to 2 GeV/c in transverse momentum and from 0 to 0.85 in Feynman x. The results are compared to existing data in overlapping energy ranges.
Double differential cross sections for PI+ and PI- in P P interactions at 158 GeV.
Double differential cross sections for PI+ and PI- in P P interactions at 158 GeV.
Double differential cross sections for PI+ and PI- in P P interactions at 158 GeV.
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