In the reaction p p → 3π + 3π − 2227 events, and in the reaction p p → 3π + 3π − π 0 6578 events have been analyzed. The general characteristics of the reactions, such as total cross sections, angular and momentum distributions, the production of ϱ, f, ω and η mesons, and angular correlations are presented.
No description provided.
THETA being the angle between PI+ and P (or PI- and PBAR) in CMS.
THETA being the angle between PI+ and P (or PI- and PBAR) in CMS.
Absolute cross sections for Compton scattering from protons have been determined at 180° for the backscattered photon at incident laboratory photon energies of 98 and 132 MeV. For the difference between the electric and the magnetic polarizability of the proton a value of (7.03 − 2.37 +2.49 − 2.05 +2.14 ) × 10 −4 fm 3 has been derived using the predictions from calculations based on relativistic dispersion relations.
No description provided.
The total cross section of the pp→ pp η reaction has been measured at incident proton energies of 1.265, 1.3, 1.4 and 1.5 GeV by detecting the two photons from the η decay in the PINOT spectrometer. The data are compared with other near-threshold measurements and with the predictions of existing theoretical calculations.
Value given at 1263 MeV assumes energy 2 MeV lower than nominal value. This uncertainty only affects this lowest energy point.
The doubly-differential cross sections for the pp → ppη and pd → ηX reactions have been measured at incident proton energies of 1.3 and 1.5 GeV. The ratio of the pd to pp -induced cross sections varies from about 8–10 at 1.3 GeV to 4.5–6 at 1.5 GeV in the η kinetic energy interval 100 MeV ⩽ T η ⩽220 MeV. Information on the pn → ηX reaction has been extracted from these measurements within the framework of a simple folding model.
No description provided.
No description provided.
No description provided.
We present results on Λc+ production in 29-GeV e+e− annihilation. The Λc+ are observed via their semileptonic decays to Λe+X and Λμ+X. With radiative corrections, we find σ(e+e−→Λc+X)〉BΛc+→eΛX)= 1.5±0.6±0.5 pb or 0.0038±0.0015±0.0012 Λc+→Λe+X decay per hadronic event, and σ(e+e−Λc+X)B(Λc+→μΛX)= 1.4±1.4±0.4 pb or 0.0035±0.0035±0.0011 Λc+→Λμ+X decay per hadronic event. These results can be used to place constraints on the predictions of various production models.
Cross sections * branching ratio for LAMBDA/C+ production in LAMBDA E+ decay channel.
Cross sections * branching ratio for LAMBDA/C+ production in LAMBDA MU+ decay channel.
The production of strange hadrons (K$^{0}_{\rm S}$, $\Lambda$, $\Xi^{\pm}$, and $\Omega^{\pm}$), baryon-to-meson ratios ($\Lambda/{\rm K}^0_{\rm S}$, $\Xi/{\rm K}^0_{\rm S }$, and $\Omega/{\rm K}^0_{\rm S}$), and baryon-to-baryon ratios ($\Xi/\Lambda$, $\Omega/\Lambda$, and $\Omega/\Xi$) associated with jets and the underlying event were measured as a function of transverse momentum ($p_{\rm T}$) in pp collisions at $\sqrt{s} = 13$ TeV and p-Pb collisions at $\sqrt{s_{\rm NN}} = 5.02$ TeV with the ALICE detector at the LHC. The inclusive production of the same particle species and the corresponding ratios are also reported. The production of multi-strange hadrons, $\Xi^{\pm}$ and $\Omega^{\pm}$, and their associated particle ratios in jets and in the underlying event are measured for the first time. In both pp and p-Pb collisions, the baryon-to-meson and baryon-to-baryon yield ratios measured in jets differ from the inclusive particle production for low and intermediate hadron $p_{\rm T}$ (0.6$-$6 GeV/$c$). Ratios measured in the underlying event are in turn similar to those measured for inclusive particle production. In pp collisions, the particle production in jets is compared with PYTHIA 8 predictions with three colour-reconnection implementation modes. None of them fully reproduces the data in the measured hadron $p_{\rm T}$ region. The maximum deviation is observed for $\Xi^{\pm}$ and $\Omega^{\pm}$, which reaches a factor of about six. In p-Pb collisions, there is no significant event-multiplicity dependence for particle production in jets, in contrast to what is observed in the underlying event. The presented measurements provide novel constraints on hadronisation and its Monte Carlo description. In particular, they demonstrate that the fragmentation of jets alone is insufficient to describe the strange and multi-strange particle production in hadronic collisions at LHC energies.
$p_{\rm T}$-differential density of inclusive ${\rm K}_{\rm S}^{0}$ and $\Lambda$ ($\overline{\Lambda}$) in pp collisions at $\sqrt{s} = 13$ TeV.
$p_{\rm T}$-differential densities of ${\rm K}_{\rm S}^{0}$ and $\Lambda$ ($\overline{\Lambda}$) in jets and the underlying event in pp collisions at $\sqrt{s} = 13$ TeV.
$p_{\rm T}$-differential density of inclusive $\Xi^{\pm}$ in pp collisions at $\sqrt{s} = 13$ TeV.
The production of inclusive, prompt and non-prompt J/$\psi$ was studied for the first time at midrapidity ($ -1.37 < y_{\rm cms} < 0.43$) in p$-$Pb collisions at $\sqrt{s_{\rm NN}} = 8.16$ TeV with the ALICE detector at the LHC. The inclusive J/$\psi$ mesons were reconstructed in the dielectron decay channel in the transverse momentum ($p_{\rm T}$) interval $0 < p_{\rm T} < 14$ GeV/$c$ and the prompt and non-prompt contributions were separated on a statistical basis for $p_{\rm T} > 2$ GeV/$c$. The study of the J/$\psi$ mesons in the dielectron channel used for the first time in ALICE online single-electron triggers from the Transition Radiation Detector, providing a data sample corresponding to an integrated luminosity of $689 \pm 13 \mu{\rm b}^{-1}$. The proton$-$proton reference cross section for inclusive J/$\psi$ was obtained based on interpolations of measured data at different centre-of-mass energies and a universal function describing the $p_{\rm T}$-differential J/$\psi$ production cross sections. The $p_{\rm T}$-differential nuclear modification factors $R_{\rm pPb}$ of inclusive, prompt, and non-prompt J/$\psi$ are consistent with unity and described by theoretical models implementing only nuclear shadowing.
d$^2\sigma$/d$y$d$p_{\rm T}$ in bins of $p_{\mathrm{T}}^{J/\psi}$ for inclusive J/$\psi$ in p--Pb collisions at $\sqrt{s_{NN}}$ = 8.16 TeV.
Nuclear modification factor ($R_{pPb}$) of inclusive J/$\psi$ in p--Pb collisions at $\sqrt{s_{NN}}$ = 8.16 TeV at midrapidity.
$p_\mathrm{T}$ integrated nuclear modification factor ($R_{pPb}$) of inclusive J/$\psi$ in p--Pb collisions at $\sqrt{s_{NN}}$ = 8.16 TeV at midrapidity.
The interactions of kaons (K) and antikaons ($\mathrm{\overline{K}}$) with few nucleons (N) were studied so far using kaonic atom data and measurements of kaon production and interaction yields in nuclei. Some details of the three-body KNN and $\mathrm{\overline{K}}$NN dynamics are still not well understood, mainly due to the overlap with multi-nucleon interactions in nuclei. An alternative method to probe the dynamics of three-body systems with kaons is to study the final state interaction within triplet of particles emitted in pp collisions at the Large Hadron Collider, which are free from effects due to the presence of bound nucleons. This Letter reports the first femtoscopic study of p$-$p$-$K$^+$ and p$-$p$-$K$^-$ correlations measured in high-multiplicity pp collisions at $\sqrt{s}$ = 13 TeV by the ALICE Collaboration. The analysis shows that the measured p$-$p$-$K$^+$ and p$-$p$-$K$^-$ correlation functions can be interpreted in terms of pairwise interactions in the triplets, indicating that the dynamics of such systems is dominated by the two-body interactions without significant contributions from three-body effects or bound states.
The (p-p)-K$^+$ correlation function obtained using the data-driven approach.
The p-(p-K$^+$) correlation function obtained using the data-driven approach.
Lower-order contributions to the p-p-K$^+$ correlation function obtained using the data-driven approach.
A newly developed observable for correlations between symmetry planes, which characterize the direction of the anisotropic emission of produced particles, is measured in Pb-Pb collisions at $\sqrt{s_{\rm NN}} = 2.76$ TeV with ALICE. This so-called Gaussian Estimator allows for the first time the study of these quantities without the influence of correlations between different flow amplitudes. The centrality dependence of various correlations between two, three and four symmetry planes is presented. The ordering of magnitude between these symmetry plane correlations is discussed and the results of the Gaussian Estimator are compared with measurements of previously used estimators. The results utilizing the new estimator lead to significantly smaller correlations than reported by studies using the Scalar Product method. Furthermore, the obtained symmetry plane correlations are compared to state-of-the-art hydrodynamic model calculations for the evolution of heavy-ion collisions. While the model predictions provide a qualitative description of the data, quantitative agreement is not always observed, particularly for correlators with significant non-linear response of the medium to initial state anisotropies of the collision system. As these results provide unique and independent information, their usage in future Bayesian analysis can further constrain our knowledge on the properties of the QCD matter produced in ultrarelativistic heavy-ion collisions.
Centrality dependence of $\langle \cos[4(\Psi_{4}-\Psi_{2})]\rangle_{\mathrm{GE}}$ in Pb--Pb collisions at $\sqrt{s_{\rm NN}} = 2.76$ TeV.
Centrality dependence of $\langle \cos[6(\Psi_{6}-\Psi_{3})]\rangle_{\mathrm{GE}}$ in Pb--Pb collisions at $\sqrt{s_{\rm NN}} = 2.76$ TeV.
Centrality dependence of $\langle \cos[6(\Psi_{2}-\Psi_{3})]\rangle_{\mathrm{GE}}$ in Pb--Pb collisions at $\sqrt{s_{\rm NN}} = 2.76$ TeV.
The production of $\pi^\pm$, ${\rm K}^\pm$, and $(\overline{\rm p})$p is measured in pp collisions at $\sqrt{s}=13$ TeV in different topological regions. Particle transverse momentum ($p_{\rm T}$) spectra are measured in the ``toward'', ``transverse'', and ``away'' angular regions defined with respect to the direction of the leading particle in the event. While the toward and away regions contain the fragmentation products of the near-side and away-side jets, respectively, the transverse region is dominated by particles from the Underlying Event (UE). The relative transverse activity classifier, $R_{\rm T}=N_{\rm T}/\langle N_{\rm T}\rangle$, is used to group events according to their UE activity, where $N_{\rm T}$ is the measured charged-particle multiplicity per event in the transverse region and $\langle N_{\rm T}\rangle$ is the mean value over all the analysed events. The first measurements of identified particle $p_{\rm T}$ spectra as a function of $R_{\rm T}$ in the three topological regions are reported. The yield of high transverse momentum particles relative to the $R_{\rm T}$-integrated measurement decreases with increasing $R_{\rm T}$ in both the toward and away regions, indicating that the softer UE dominates particle production as $R_{\rm T}$ increases and validating that $R_{\rm T}$ can be used to control the magnitude of the UE. Conversely, the spectral shapes in the transverse region harden significantly with increasing $R_{\rm T}$. This hardening follows a mass ordering, being more significant for heavier particles. The $p_{\rm T}$-differential particle ratios $({\rm p+\overline{p}})/(\pi^+ +\pi^-)$ and $({\rm K^+ +K^-})/(\pi^+ +\pi^-)$ in the low UE limit $(R_{\rm T}\rightarrow 0)$ approach expectations from Monte Carlo generators such as PYTHIA 8 with Monash 2013 tune and EPOS LHC, where the jet-fragmentation models have been tuned to reproduce ${\rm e^+ e^-}$ results.
$N_{\mathrm{T}}$ probability distribution in the transverse region using events with leading particles $(p_{\mathrm{T}}^{\mathrm{leading}} \geq 5~\mathrm{GeV}/c)$ in the pseudorapidity interval $|\eta|<0.8$ in pp collisions at $\sqrt{s} = 13~\mathrm{TeV}$.
$R_{\mathrm{T}}$ probability distribution in the transverse region using events with leading particles $(p_{\mathrm{T}}^{\mathrm{leading}} \geq 5~\mathrm{GeV}/c)$ in the pseudorapidity interval $|\eta|<0.8$ in pp collisions at $\sqrt{s} = 13~\mathrm{TeV}$.
$\pi^{+}+\pi^{-}$ transverse momentum spectrum for events with $0 \leq R_{\mathrm{T}} < 5$ in the Toward region in pp collisions at $\sqrt{s} = 13~\mathrm{TeV}$.
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