The interaction of $\rm{K}^{-}$ with protons is characterised by the presence of several coupled channels, systems like ${\rm \overline{K}^0}$n and $\pi\Sigma$ with a similar mass and the same quantum numbers as the $\rm{K}^{-}$p state. The strengths of these couplings to the $\rm{K}^{-}$p system are of crucial importance for the understanding of the nature of the $\Lambda(1405)$ resonance and of the attractive $\rm{K}^{-}$p strong interaction. In this article, we present measurements of the $\rm{K}^{-}$p correlation functions in relative momentum space obtained in pp collisions at $\sqrt{s}~=~13$ TeV, in p-Pb collisions at $\sqrt{s_{\mathrm{NN}}}~=~5.02$ TeV, and (semi)peripheral Pb-Pb collisions at $\sqrt{s_{\mathrm{NN}}}~=~5.02$ TeV. The emitting source size, composed of a core radius anchored to the $\rm{K}^{+}$p correlation and of a resonance halo specific to each particle pair, varies between 1 and 2 fm in these collision systems. The strength and the effects of the ${\rm \overline{K}^0}$n and $\pi\Sigma$ inelastic channels on the measured $\rm{K}^{-}$p correlation function are investigated in the different colliding systems by comparing the data with state-of-the-art models of chiral potentials. A novel approach to determine the conversion weights $\omega$, necessary to quantify the amount of produced inelastic channels in the correlation function, is presented. In this method, particle yields are estimated from thermal model predictions, and their kinematic distribution from blast-wave fits to measured data. The comparison of chiral potentials to the measured $\rm{K}^{-}$p interaction indicates that, while the $\pi\Sigma-\rm{K}^{-}$p dynamics is well reproduced by the model, the coupling to the ${\rm \overline{K}^0}$n channel in the model is currently underestimated.
K$^+$p (K$^+$p $\oplus$ K$^-\overline{\mathrm p}$) correlation function in pp collisions at $\sqrt{s}=13$ TeV.
K$^+$p (K$^+$p $\oplus$ K$^-\overline{\mathrm p}$) correlation function in p-Pb collisions at $\sqrt{s_{\mathrm {NN}}}=5.02 $ TeV (0-20%).
K$^+$p (K$^+$p $\oplus$ K$^-\overline{\mathrm p}$) correlation function in p-Pb collisions at $\sqrt{s_{\mathrm{NN}}}=5.02$ TeV (20-40%).
Hadronic resonances are used to probe the hadron gas produced in the late stage of heavy-ion collisions since they decay on the same timescale, of the order of 1 to 10 fm/$c$, as the decoupling time of the system. In the hadron gas, (pseudo)elastic scatterings among the products of resonances that decayed before the kinetic freeze-out and regeneration processes counteract each other, the net effect depending on the resonance lifetime, the duration of the hadronic phase, and the hadronic cross sections at play. In this context, the $\Sigma(1385)^{\pm}$ particle is of particular interest as models predict that regeneration dominates over rescattering despite its relatively short lifetime of about 5.5 fm/$c$. The first measurement of the $\Sigma(1385)^{\pm}$ resonance production at midrapidity in Pb-Pb collisions at $\sqrt{s_{\mathrm{NN}}}= 5.02$ TeV with the ALICE detector is presented in this Letter. The resonances are reconstructed via their hadronic decay channel, $\Lambda\pi$, as a function of the transverse momentum ($p_{\rm T}$) and the collision centrality. The results are discussed in comparison with the measured yield of pions and with expectations from the statistical hadronization model as well as commonly employed event generators, including PYTHIA8/Angantyr and EPOS3 coupled to the UrQMD hadronic cascade afterburner. None of the models can describe the data. For $\Sigma(1385)^{\pm}$, a similar behaviour as ${\rm K}^{*} (892)^{0}$ is observed in data unlike the predictions of EPOS3 with afterburner.
$p_{\rm{T}}$-differential yield of $\Sigma^{*+}$ + cc in Pb-Pb collisions with centre-of-mass energy/nucleon=5.02 TeV (0-10% multiplicity class).
$p_{\rm{T}}$-differential yield of $\Sigma^{*+}$ + cc in Pb-Pb collisions with centre-of-mass energy/nucleon=5.02 TeV (30-50% multiplicity class).
$p_{\rm{T}}$-differential yield of $\Sigma^{*+}$ + cc in Pb-Pb collisions with centre-of-mass energy/nucleon=5.02 TeV (50-90% multiplicity class).
The production of the W$^\pm$ bosons measured in p$-$Pb collisions at a centre-of-mass energy per nucleon$-$nucleon collision $\sqrt{s_{NN}} = 8.16$ TeV and Pb$-$Pb collisions at $\sqrt{s_{NN}} = 5.02$ TeV with ALICE at the LHC is presented. The W$^\pm$ bosons are measured via their muonic decay channel, with the muon reconstructed in the pseudorapidity region $-4 < \eta^\mu_{\rm lab} < -2.5$ with transverse momentum $p_{\rm T}^\mu > 10$ GeV/$c$. While in Pb$-$Pb collisions the measurements are performed in the forward ($2.5 < y^\mu_{\rm cms} < 4$) rapidity region, in p$-$Pb collisions, where the centre-of-mass frame is boosted with respect to the laboratory frame, the measurements are performed in the backward ($-4.46 < y^\mu_{\rm cms} < -2.96$) and forward ($2.03 < y^\mu_{\rm cms} < 3.53$) rapidity regions. The W$^{-}$ and W$^{+}$ production cross sections, lepton-charge asymmetry, and nuclear modification factors are evaluated as a function of the muon rapidity. In order to study the production as a function of the p$-$Pb collision centrality, the production cross sections of the W$^{-}$ and W$^{+}$ bosons are combined and normalised to the average number of binary nucleon$-$nucleon collision $\langle N_\mathrm{coll} \rangle$. In Pb$-$Pb collisions, the same measurements are presented as a function of the collision centrality. Study of the binary scaling of the W$^\pm$-boson cross sections in p$-$Pb and Pb$-$Pb collisions is also reported. The results are compared with perturbative QCD (pQCD) calculations, with and without nuclear modifications of the Parton Distribution Functions (PDFs), as well as with available data at the LHC. Significant deviations from the theory expectations are found in the two collision systems, indicating that the measurements can provide additional constraints for the determination of nuclear PDF (nPDFs) and in particular of the light-quark distributions.
d$\sigma$ / d$y$ of muons from W decays in p-Pb, in full fiducial region
d$\sigma$ / d$y$ of muons from W decays in p-Pb, in rapidity bins
Lepton-charge asymmetry $A_{ch} = \frac{N_{\mu^+} - N_{\mu^-}}{N_{\mu^+} + N_{\mu^-}}$ in p-Pb
This article presents measurements of the groomed jet radius and momentum splitting fraction in pp collisions at $\sqrt{s}=5.02$ TeV with the ALICE detector at the Large Hadron Collider. Inclusive charged-particle jets are reconstructed at midrapidity using the anti-$k_{\rm{T}}$ algorithm for transverse momentum $60< p_{\mathrm{T}}^{\rm{ch\; jet}}<80$ GeV/$c$. We report results using two different grooming algorithms: soft drop and, for the first time, dynamical grooming. For each grooming algorithm, a variety of grooming settings are used in order to explore the impact of collinear radiation on these jet substructure observables. These results are compared to perturbative calculations that include resummation of large logarithms at all orders in the strong coupling constant. We find good agreement of the theoretical predictions with the data for all grooming settings considered.
Groomed jet momentum splitting fraction $z_{{\mathrm{g}}}$ $60<p_{\mathrm{T}}^{\mathrm{ch\;jet}}<80$ GeV/$c$, soft drop $z_{\mathrm{cut}}=0.1, \beta=0$. Note: The first bin corresponds to the Soft Drop untagged fraction. For the "trkeff" and "generator" systematic uncertainty sources, the signed systematic uncertainty breakdowns ($\pm$ vs. $\mp$), denote correlation across bins (both within this table, and across tables). For the remaining sources ("unfolding") no correlation information is specified ($\pm$ is always used).
Groomed jet momentum splitting fraction $z_{{\mathrm{g}}}$ $60<p_{\mathrm{T}}^{\mathrm{ch\;jet}}<80$ GeV/$c$, soft drop $z_{\mathrm{cut}}=0.1, \beta=1$. Note: The first bin corresponds to the Soft Drop untagged fraction. For the "trkeff" and "generator" systematic uncertainty sources, the signed systematic uncertainty breakdowns ($\pm$ vs. $\mp$), denote correlation across bins (both within this table, and across tables). For the remaining sources ("unfolding") no correlation information is specified ($\pm$ is always used).
Groomed jet momentum splitting fraction $z_{{\mathrm{g}}}$ $60<p_{\mathrm{T}}^{\mathrm{ch\;jet}}<80$ GeV/$c$, soft drop $z_{\mathrm{cut}}=0.1, \beta=2$. Note: The first bin corresponds to the Soft Drop untagged fraction. For the "trkeff" and "generator" systematic uncertainty sources, the signed systematic uncertainty breakdowns ($\pm$ vs. $\mp$), denote correlation across bins (both within this table, and across tables). For the remaining sources ("unfolding") no correlation information is specified ($\pm$ is always used).
The multiplicity dependence of jet production in pp collisions at the centre-of-mass energy of $\sqrt{s} = 13\ \mathrm{TeV}$ is studied for the first time. Jets are reconstructed from charged particles using the anti-$k_\mathrm{T}$ algorithm with resolution parameters $R$ varying from $0.2$ to $0.7$. The jets are measured in the pseudorapidity range $|\eta_{\rm jet}|< 0.9-R$ and in the transverse momentum range $5<p_\mathrm{T,jet}^{\rm ch}<140\ \mathrm{GeV}/c$. The multiplicity intervals are categorised by the ALICE forward detector V0. The $p_{\mathrm{T}}$ differential cross section of charged-particle jets are compared to leading order (LO) and next-to-leading order (NLO) perturbative quantum chromodynamics (pQCD) calculations. It is found that the data are better described by the NLO calculation, although the NLO prediction overestimates the jet cross section below $20\ \mathrm{GeV}/c$. The cross section ratios for different $R$ are also measured and compared to model calculations. These measurements provide insights into the angular dependence of jet fragmentation. The jet yield increases with increasing self-normalised charged-particle multiplicity. This increase shows only a weak dependence on jet transverse momentum and resolution parameter at the highest multiplicity. While such behaviour is qualitatively described by the present version of PYTHIA, quantitative description may require implementing new mechanisms for multi-particle production in hadronic collisions.
Inclusive charged-particle jet cross sections in pp collisions at $\sqrt{s}$ = 13 TeV using the anti-kT algorithm for different jet resolution parameters R from 0.2 to 0.7, with UE subtraction. Statistical uncertainties are displayed as vertical error bars. The total systematic uncertainties are shown as solid boxes around the data points.
Ratio of charged-particle jet cross section for resolution parameter R = 0.2 to other radii R = X, with X ranging from 0.3 to 0.7, after UE subtraction. Data are compared with LO (PYTHIA) and NLO (POWHEG+PYTHIA8) predictions as shown in the bottom panels. The systematic uncertainties of the cross section ratios from data are indicated by solid boxes around data points in the upper panel and shaded bands around unity in the mid and lower panels. No uncertainties are shown for theoretical predictions for better visibility.
Charged-particle jet yields in different V0M multiplicity percentile intervals for resolution parameters R varied from 0.2 to 0.7 in pp collisions at s = 13 TeV. Statistical and total systematic uncertainties are shown as vertical error bars and boxes around the data points, respectively.
In our Galaxy, light antinuclei composed of antiprotons and antineutrons can be produced through high-energy cosmic-ray collisions with the interstellar medium or could also originate from the annihilation of dark-matter particles that have not yet been discovered. On Earth, the only way to produce and study antinuclei with high precision is to create them at high-energy particle accelerators. Although the properties of elementary antiparticles have been studied in detail, the knowledge of the interaction of light antinuclei with matter is limited. We determine the disappearance probability of $^{3}\overline{\rm He}$ when it encounters matter particles and annihilates or disintegrates within the ALICE detector at the Large Hadron Collider. We extract the inelastic interaction cross section, which is then used as input to calculations of the transparency of our Galaxy to the propagation of $^{3}\overline{\rm He}$ stemming from dark-matter annihilation and cosmic-ray interactions within the interstellar medium. For a specific dark-matter profile, we estimate a transparency of about 50%, whereas it varies with increasing $^{3}\overline{\rm He}$ momentum from 25% to 90% for cosmic-ray sources. The results indicate that $^{3}\overline{\rm He}$ nuclei can travel long distances in the Galaxy, and can be used to study cosmic-ray interactions and dark-matter annihilation.
Raw primary antihelium3-to-helium3 ratio as a function of the momentum p_primary.
Raw primary antihelium3-to-helium3 ratio from Geant4-based MC simulations as a function of the momentum p_primary with default sigma_inel(3Hebar).
Raw primary antihelium3-to-helium3 ratio from Geant4-based MC simulations as a function of the momentum p_primary with sigma_inel(3Hebar)x0.5.
The production of non-prompt ${\rm D}^{0}$ mesons from beauty-hadron decays was measured at midrapidity ($\left| y \right| < 0.5$) in Pb-Pb collisions at a nucleon-nucleon center-of-mass energy of $\sqrt{s_{\rm NN}}=5.02~\mathrm{TeV}$ with the ALICE experiment at the LHC. Their nuclear modification factor ($R_{\rm AA}$), measured for the first time down to $p_{\rm T}=1~\mathrm{GeV}/c$ in the $0-10$% and $30-50$% centrality classes, indicates a significant suppression, up to a factor of about three, for $p_{\rm T} > 5~\mathrm{GeV}/c$ in the $0-10$% central Pb-Pb collisions. The data are described by models that include both collisional and radiative processes in the calculation of beauty-quark energy loss in the quark-gluon plasma, and quark recombination in addition to fragmentation as a hadronisation mechanism. The ratio of the non-prompt to prompt ${\rm D}^{0}$-meson $R_{\rm AA}$ is larger than unity for $p_{\rm T} > 4~\mathrm{GeV}/c$ in the $0-10$% central Pb-Pb collisions, as predicted by models in which beauty quarks lose less energy than charm quarks in the quark-gluon plasma because of their larger mass.
Transverse-momentum-differential production yields of non-prompt $\rm D^0$ in central (0-10%) and mid-central (30-50%) Pb-Pb collisions at $\sqrt{s_{\mathrm{NN}}}=5.02$ TeV.
The nuclear modification factor of non-prompt $\rm D^0$ as a function of transverse momentum in central (0-10%) and mid-central (30-50%) Pb-Pb collisions at $\sqrt{s_{\mathrm{NN}}}=5.02$ TeV.
The non-prompt to prompt $\rm D^0$-meson nuclear modification factor ratio as a function of transverse momentum in central (0-10%) Pb-Pb collisions at $\sqrt{s_{\mathrm{NN}}}=5.02$ TeV.
This article presents the first measurement of the interaction between charm hadrons and nucleons. The two-particle momentum correlations of $\mathrm{pD^-}$ and $\mathrm{\overline{p}D}^+$ pairs are measured by the ALICE Collaboration in high-multiplicity pp collisions at $\sqrt{s} = 13~\mathrm{TeV}$. The data are compatible with the Coulomb-only interaction hypothesis within (1.1-1.5)$\sigma$. The level of agreement slightly improves if an attractive nucleon(N)$\overline{\mathrm{D}}$ strong interaction is considered, in contrast to most model predictions which suggest an overall repulsive interaction. This measurement allows for the first time an estimation of the 68% confidence level interval for the isospin $\mathrm{I}=0$ inverse scattering length of the $\mathrm{N\overline{D}}$ state ${f_{0,~\mathrm{I}=0}^{-1} \in [-0.4,0.9]~\mathrm{fm^{-1}}}$, assuming negligible interaction for the isospin $\mathrm{I}=1$ channel.
$\mathrm{pD^-}$ $\oplus$ $\mathrm{\overline{p}D^+}$ momentum correlation function as a function of the relative momentum in the particle-pair rest frame $k^*$ in high-multiplicity (0-0.17%) pp collisions at $\sqrt{s}=13$ TeV.
$1\sigma$ confidence interval for the $\mathrm{N\overline{D}}$ inverse scattering length for the isospin $\mathrm{I}=0$ channel, $f_{0,~\mathrm{I}=0}^{-1}$, as a function of the effective source radius $R_\mathrm{eff}$.
Best fit for the $\mathrm{N\overline{D}}$ inverse scattering length for the isospin $\mathrm{I}=0$ channel, $f_{0,~\mathrm{I}=0}^{-1}$, as a function of the effective source radius $R_\mathrm{eff}$.
We present the first measurement of event-by-event fluctuations in the kaon sector in Pb-Pb collisions at $\sqrt {s_{\rm NN}}=$ 2.76 TeV with the ALICE detector at the LHC. The robust fluctuation correlator $\nu_{\rm dyn}$ is used to evaluate the magnitude of fluctuations of the relative yields of neutral and charged kaons, as well as the relative yields of charged kaons, as a function of collision centrality and selected kinematic ranges. While the correlator $\nu_{\rm dyn}[\rm K^+,\rm K^-]$ exhibits a scaling approximately in inverse proportion of the charged particle multiplicity, $\nu_{\rm dyn}[\rm K_S^0,\rm K^{\pm}]$ features a significant deviation from such scaling. Within uncertainties, the value of $\nu_{\rm dyn}[\rm K_S^0,\rm K^{\pm}]$ is independent of the selected transverse momentum interval, while it exhibits a pseudorapidity dependence. The results are compared with HIJING, AMPT and EPOS-LHC predictions, and are further discussed in the context of the possible production of disoriented chiral condensates in central Pb-Pb collisions.
The production of J/$\psi$ is measured as a function of charged-particle multiplicity at forward rapidity in proton$-$proton (pp) collisions at center-of-mass energies $\sqrt{s} =$ 5.02 and 13 TeV. The J/$\psi$ mesons are reconstructed via their decay into dimuons in the rapidity interval (2.5 $< y <$ 4.0), whereas the charged-particle multiplicity density (${\rm d}N_{\rm{ch}}/{\rm d}\eta$) is measured at midrapidity $(|\eta| < 1)$. The production rate as a function of multiplicity is reported as the ratio of the yield in a given multiplicity interval to the multiplicity-integrated one. This observable shows a linear increase with charged-particle multiplicity normalized to the corresponding average value for inelastic events (${{\rm d}N_{\rm ch}/{\rm d}\eta}/{\langle {\rm d}N_{\rm ch}/{\rm d}\eta \rangle}$), at both the colliding energies. Measurements are compared with available ALICE results at midrapidity and theoretical model calculations. First measurement of the mean transverse momentum ($\langle p_{\mathrm{T}}\rangle$) of J/$\psi$ in pp collisions exhibits an increasing trend as a function of ${{\rm d}N_{\rm ch}/{\rm d}\eta}/{\langle {\rm d}N_{\rm ch}/{\rm d}\eta \rangle}$ showing a saturation towards high charged-particle multiplicities.
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