Measurements of the double differential cross sections for ππ and pπ production in pp collisions at the CERN ISR are presented for 5 c.m. energies s = 22, 30, 44, 53, 62 GeV . Charge and transverse momentum correlations are also reported.
The analyzing powers of π+ and π− were measured using an incident 22−GeV/c transversely polarized proton beam at the Brookhaven Alternating Gradient Synchrotron. A magnetic spectrometer measured π± inclusive asymmetries on a hydrogen and a carbon target. An elastic polarimeter with a CH2 target measured pp elastic-scattering asymmetries to determine the beam polarization using published data for the pp elastic analyzing power. Using the beam polarization determined from the elastic polarimeter and asymmetries from the inclusive spectrometer, analyzing powers AN for π± were determined in the xF and pT ranges (0.45–0.8) and (0.3–1.2 GeV/c), respectively. The analyzing power results are similar in both sign and character to other measurements at 200 and 11.7 GeV/c, confirming the expectation that high-energy pion inclusive analyzing powers remain large and relatively energy independent. This suggests that pion inclusive polarimetry may be a suitable method for measuring future beam polarizations at BNL RHIC or DESY HERA. Analyzing powers of π+ and π− produced on hydrogen and carbon targets are the same. Various models to explain inclusive analyzing powers are also discussed.
Mid-rapidity production of $\pi^{\pm}$, $\rm{K}^{\pm}$ 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/$\pi$) and kaon-to-pion (K/$\pi$) ratios, with similar measurements in Pb-Pb collisions at $\sqrt{s_{\rm{NN}}}$ = 2.76 TeV show no significant energy dependence. Blast-wave fits of the $p_{\rm{T}}$ spectra indicate that in the most central collisions radial flow is slightly larger at 5.02 TeV with respect to 2.76 TeV. Particle ratios (p/$\pi$, K/$\pi$) as a function of $p_{\rm{T}}$ show pronounced maxima at $p_{\rm{T}}$ $\approx$ 3 GeV/$c$ in central Pb-Pb collisions. At high $p_{\rm{T}}$, particle ratios at 5.02 TeV are similar to those measured in pp collisions at the same energy and in Pb-Pb collisions at $\sqrt{s_{\rm{NN}}}$ = 2.76 TeV. Using the pp reference spectra measured at the same collision energy of 5.02 TeV, the nuclear modification factors for the different particle species are derived. Within uncertainties, the nuclear modification factor is particle species independent for high $p_{\rm{T}}$ and compatible with measurements at $\sqrt{s_{\rm{NN}}}$ = 2.76 TeV. The results are compared to state-of-the-art model calculations, which are found to describe the observed trends satisfactorily.
$p_{T}$-distributions of pions ($\pi^{+}+\pi^{-}$) measured in Pb-Pb collisions at $\sqrt{s_{NN}}$ = 5.02 TeV.
$p_{T}$-distributions of pions ($\pi^{+}+\pi^{-}$) measured in pp collisions at $\sqrt{s}$ = 5.02 TeV.
$p_{T}$-distributions of kaons ($K^{+}+K^{-}$) measured in Pb-Pb collisions at $\sqrt{s_{NN}}$ = 5.02 TeV.
In high-energy collisions, the spatio-temporal size of the particle production region can be measured using the Bose-Einstein correlations of identical bosons at low relative momentum. The source radii are typically extracted using two-pion correlations, and characterize the system at the last stage of interaction, called kinetic freeze-out. In low-multiplicity collisions, unlike in high-multiplicity collisions, two-pion correlations are substantially altered by background correlations, e.g. mini-jets. Such correlations can be suppressed using three-pion cumulant correlations. We present the first measurements of the size of the system at freeze-out extracted from three-pion cumulant correlations in pp, p-Pb and Pb-Pb collisions at the LHC with ALICE. At similar multiplicity, the invariant radii extracted in p-Pb collisions are found to be 5-15% larger than those in pp, while those in Pb-Pb are 35-55% larger than those in p-Pb. Our measurements disfavor models which incorporate substantially stronger collective expansion in p-Pb as compared to pp collisions at similar multiplicity.
Mixed charge C3 and c3 in pp collisions projected against 1 of a mixed-charge pair invariant relative momentum.
Same charge C3 and c3 in pp collisions projected against Q3.
Same charge C3 and c3 in p Pb collisions projected against Q3.
Measurements of $\rm{K}^{*}(892)^{0}$ and $\phi(1020)$ resonance production in Pb-Pb and pp collisions at $\sqrt{s_{\rm{NN}}}$ = 5.02 TeV with the ALICE detector at the Large Hadron Collider are reported. The resonances are measured at midrapidity ($|y|$ $<$ 0.5) via their hadronic decay channels and the transverse momentum ($p_{\rm{T}}$) distributions are obtained for various collision centrality classes up to $p_{\rm{T}}$ $=$ 20 GeV$/c$. The $p_{\rm{T}}$-integrated yield ratio $\rm{K}^{*}(892)^{0}$$/$K in Pb-Pb collisions shows significant suppression relative to pp collisions and decreases towards more central collisions. In contrast, the $\phi(1020)$$/$K ratio does not show any suppression. Furthermore, the measured $\rm{K}^{*}(892)^{0}$$/$K ratio in central Pb-Pb collisions is significantly suppressed with respect to the expectations based on a thermal model calculation, while the $\phi(1020)$$/$K ratio agrees with the model prediction. These measurements are an experimental demonstration of rescattering of $\rm{K}^{*}(892)^{0}$ decay products in the hadronic phase of the collisions. The $\rm{K}^{*}(892)^{0}$$/$K yield ratios in Pb-Pb and pp collisions are used to estimate the time duration between chemical and kinetic freeze-out, which is found to be $\sim$ 4-7 fm$/c$ for central collisions. The $p_{\rm{T}}$-differential ratios of $\rm{K}^{*}(892)^{0}$$/$K, $\phi(1020)$$/$K, $\rm{K}^{*}(892)^{0}$$/\pi$, $\phi(1020)$$/\pi$, $p/$$\rm{K}^{*}(892)^{0}$ and $p/$$\phi(1020)$ are also presented for Pb-Pb and pp collisions at $\sqrt{s_{\rm{NN}}}$ $=$ 5.02 TeV. These ratios show that the rescattering effect is predominantly a low-$p_{\rm{T}}$ phenomenon.
$p_{\rm T}$-distributions of $\rm{K}^{*0}$ (average of particle and anti-particle) meson measured in Pb-Pb collisions at $\sqrt{s_{NN}}$ = 5.02 TeV.
$p_{\rm T}$-distributions of $\rm{K}^{*0}$ (average of particle and anti-particle) meson measured in pp collisions at $\sqrt{s}$ = 5.02 TeV.
$p_{\rm T}$-distributions of $\phi$ meson measured in Pb-Pb collisions at $\sqrt{s_{NN}}$ = 5.02 TeV.
Transverse momentum distributions and yields for $\pi^{\pm}$, $K^{\pm}$, $p$ and $\bar{p}$ in $p+p$ collisions at $\sqrt{s}$=200 and 62.4 GeV at midrapidity are measured by the PHENIX experiment at the Relativistic Heavy Ion Collider (RHIC). These data provide important baseline spectra for comparisons with identified particle spectra in heavy ion collisions at RHIC. We present the inverse slope parameter $T_{\rm inv}$, mean transverse momentum $<p_T>$ and yield per unit rapidity $dN/dy$ at each energy, and compare them to other measurements at different $\sqrt{s}$ in $p+p$ and $p+\bar{p}$ collisions. We also present the scaling properties such as $m_T$ scaling, $x_T$ scaling on the $p_T$ spectra between different energies. To discuss the mechanism of the particle production in $p+p$ collisions, the measured spectra are compared to next-to-leading-order or next-to-leading-logarithmic perturbative quantum chromodynamics calculations.
Invariant cross sections for inclusive PI+ and PI- production in P P collisions at a centre-of-mass energy of 200 GeV. There is an additional normalization uncertainty of 9.7 PCT.
Invariant cross sections for inclusive K+ and K- production in P P collisions at a centre-of-mass energy of 200 GeV. There is an additional normalization uncertainty of 9.7 PCT.
Invariant cross sections for inclusive P and PBAR production in P P collisions at a centre-of-mass energy of 200 GeV with feed-down weak decay corrections NOT applied. There is an additional normalization uncertainty of 9.7 PCT.
The production of charged pions, kaons and (anti)protons has been measured at mid-rapidity ($-0.5 y 0$) in p-Pb collisions at $\sqrt{s_{\rm NN}}=5.02$ TeV using the ALICE detector at the LHC. Exploiting particle identification capabilities at high transverse momentum ($p_{\rm T}$), the previously published $p_{\rm T}$ spectra have been extended to include measurements up to 20 GeV/$c$ for seven event multiplicity classes. The $p_{\rm T}$ spectra for pp collisions at $\sqrt{s}=7$ TeV, needed to interpolate a pp reference spectrum, have also been extended up to 20 GeV/$c$ to measure the nuclear modification factor ($R_{\rm pPb}$) in non-single diffractive p-Pb collisions. At intermediate transverse momentum ($2 p_{\rm T} 10$\,GeV/$c$) the proton-to-pion ratio increases with multiplicity in p-Pb collisions, a similar effect is not present in the kaon-to-pion ratio. The $p_{\rm T}$ dependent structure of such increase is qualitatively similar to those observed in pp and heavy-ion collisions. At high $p_{\rm T}$ ($>10$ GeV/$c$), the particle ratios are consistent with those reported for pp and Pb-Pb collisions at the LHC energies. At intermediate $p_{\rm T}$ the (anti)proton $R_{\rm pPb}$ shows a Cronin-like enhancement, while pions and kaons show little or no nuclear modification. At high $p_{\rm T}$ the charged pion, kaon and (anti)proton $R_{\rm pPb}$ are consistent with unity within statistical and systematic uncertainties.
pT-differential invariant yield of charged pions in p-Pb collisions with centre-of-mass energy/nucleon=5.02 TeV, measured for different V0A multiplicity classes. The first uncertainty is statistical, the second one is the total systematic uncertainty, while the third one is the uncorrelated systematic uncertainty which is multiplicity dependent.
pT-differential invariant yield of charged pions in p-Pb collisions with centre-of-mass energy/nucleon=5.02 TeV, measured for NSD events. The first uncertainty is statistical, the second one is the total systematic uncertainty, while the third one is the uncorrelated systematic uncertainty which is multiplicity dependent.
pT-differential invariant yield of charged kaons in p-Pb collisions with centre-of-mass energy/nucleon=5.02 TeV, measured for different V0A multiplicity classes. The first uncertainty is statistical, the second one is the total systematic uncertainty, while the third one is the uncorrelated systematic uncertainty which is multiplicity dependent.
The NA61/SHINE experiment at the CERN SPS is performing a uniqe study of the phase diagram of strongly interacting matter by varying collision energy and nuclear mass number of colliding nuclei. In central Pb+Pb collisions the NA49 experiment found structures in the energy dependence of several observables in the CERN SPS energy range that had been predicted for the transition to a deconfined phase. New measurements of NA61/SHINE find intriguing similarities in p+p interactions for which no deconfinement transition is expected at SPS energies. Possible implications will be discussed.
We present a comparative study of inclusive and semi-inclusive pion production in pp collisions at 102 and 400 GeV/ c . In particular, we examine the correlation between transverse and longitudinal momentum variables and the energy dependence of invariant cross sections.
No description provided.
The production of K$^{*}$(892)$^{0}$ and $\phi$(1020) mesons has been measured in p-Pb collisions at $\sqrt{s_{\mathrm{NN}}}$ = 5.02 TeV. K$^{*0}$ and $\phi$ are reconstructed via their decay into charged hadrons with the ALICE detector in the rapidity range $-0.5 < y <0$. The transverse momentum spectra, measured as a function of the multiplicity, have p$_{\mathrm{T}}$ range from 0 to 15 GeV/$c$ for K$^{*0}$ and from 0.3 to 21 GeV/$c$ for $\phi$. Integrated yields, mean transverse momenta and particle ratios are reported and compared with results in pp collisions at $\sqrt{s}$ = 7 TeV and Pb-Pb collisions at $\sqrt{s_{\mathrm{NN}}}$ = 2.76 TeV. In Pb-Pb and p-Pb collisions, K$^{*0}$ and $\phi$ probe the hadronic phase of the system and contribute to the study of particle formation mechanisms by comparison with other identified hadrons. For this purpose, the mean transverse momenta and the differential proton-to-$\phi$ ratio are discussed as a function of the multiplicity of the event. The short-lived K$^{*0}$ is measured to investigate re-scattering effects, believed to be related to the size of the system and to the lifetime of the hadronic phase.
$p_{\rm T}$-differential yield of (K$^{*0}$ + $\overline{K^{*0}}$)/2 in p-Pb collisions with centre-of-mass energy/nucleon=5.02 TeV (NSD). Additional systematic error: +- 3.1% (normalization).
$p_{\rm T}$-differential yield of (K$^{*0}$ + $\overline{K^{*0}}$)/2 in p-Pb collisions with centre-of-mass energy/nucleon=5.02 TeV (0-20% multiplicity class).
$p_{\rm T}$-differential yield of (K$^{*0}$ + $\overline{K^{*0}}$)/2 in p-Pb collisions with centre-of-mass energy/nucleon=5.02 TeV (20-40% multiplicity class).
Forum