The production cross sections of B$^0_\mathrm{s}$ and B$^+$ mesons are reported in proton-proton (pp) collisions recorded by the CMS experiment at the CERN LHC with a center-of-mass energy of 5.02 TeV. The data sample corresponds to an integrated luminosity of 302 pb$^{-1}$. The cross sections are based on measurements of the B$^0_\mathrm{s}$$\to$ J/$ψ(μ^+μ^-)ϕ$(1020) (K$^+$K$^-$) and B$^+$$\to$ J/$ψ(μ^+μ^-)$K$^+$ decay channels. Results are presented in the transverse momentum ($p_\mathrm{T}$) range 7-50 GeV/$c$ and the rapidity interval $\lvert y \rvert$$\lt$ 2.4 for the B mesons. The measured $p_\mathrm{T}$-differential cross sections of B$^+$ and B$^0_\mathrm{s}$ in pp collisions are well described by fixed-order plus next-to-leading logarithm perturbative quantum chromodynamics calculations. Using previous PbPb collision measurements at the same nucleon-nucleon center-of-mass energy, the nuclear modification factors, $R_\mathrm{AA}$, of the B mesons are determined. For $p_\mathrm{T}$$\lt$ 10 GeV/$c$, both mesons are found to be suppressed in PbPb collisions (with $R_\mathrm{AA}$ values significantly below unity), with less suppression observed for the B$^0_\mathrm{s}$ mesons. In this $p_\mathrm{T}$ range, the $R_\mathrm{AA}$ values for the B$^+$ mesons are consistent with those for inclusive charged hadrons and D$^0$ mesons. Below 10 GeV/$c$, both B$^+$ and B$^0_\mathrm{s}$ are found to be less suppressed than either inclusive charged hadrons or D$^0$ mesons, with the B$^0_\mathrm{s}$$R_\mathrm{AA}$ value consistent with unity. The $R_\mathrm{AA}$ values found for the B$^+$ and B$^0_\mathrm{s}$ are compared to theoretical calculations, providing constraints on the mechanism of bottom quark energy loss and hadronization in the quark-gluon plasma, the hot and dense matter created in ultrarelativistic heavy ion collisions.
The B+ meson $p_{\rm{T}}$-dependent production cross section in pp collisions. The measurment was carried out inside a fiducial region respecting ($p_{\rm{T}}$<10 & 1.5<|y|<2.4) and ($p_{\rm{T}}$>10 & |y|<2.4). The luminosity is 302.3 pb^{-1}.
The Bs meson $p_{\rm{T}}$-dependent production cross section in pp collisions. The measurment was carried out inside a fiducial region respecting (pT<10 & 1.5<|y|<2.4) and ($p_{\rm{T}}$>10 & |y|<2.4). The luminosity is 302.3 pb^{-1}.
The B+ meson $p_{\rm{T}}$-dependent RAA in PpPp. The measurment was carried out inside a fiducial region respecting ($p_{\rm{T}}$<10 & 1.5<|y|<2.4) and ($p_{\rm{T}}$>10 & |y|<2.4).
The correlations between event-by-event fluctuations of symmetry planes are measured in Pb--Pb collisions at a centre-of-mass energy per nucleon pair $\sqrt{s_{\mathrm{NN}}}$ = 5.02 TeV recorded by the ALICE detector at the Large Hadron Collider. This analysis is conducted using the Gaussian Estimator technique, which is insensitive to biases from correlations between different flow amplitudes. The study presents, for the first time, the centrality dependence of correlations involving up to five different symmetry planes. The correlation strength varies depending on the harmonic order of the symmetry plane and the collision centrality. Comparisons with measurements from lower energies indicate no significant differences within uncertainties. Additionally, the results are compared with hydrodynamic model calculations. Although the model predictions provide a qualitative explanation of the experimental results, they overestimate the data for some observables. This is particularly true for correlators that are sensitive to the non-linear response of the medium to initial-state anisotropies in the collision system. As these new correlators provide unique information -- independent of flow amplitudes -- their usage in future model developments can further constrain the properties of the strongly-interacting matter created in ultrarelativistic heavy-ion collisions.
Centrality dependence of $\langle\cos[6(\Psi_3-\Psi_2)]\rangle$ in Pb--Pb collisions at $\sqrt{s_{\rm NN}} = 5.02$ TeV.
Centrality dependence of $\langle\cos[4(\Psi_4-\Psi_2)]\rangle$ in Pb--Pb collisions at $\sqrt{s_{\rm NN}} = 5.02$ TeV.
Centrality dependence of $\langle\cos[8(\Psi_4-\Psi_2)]\rangle$ in Pb--Pb collisions at $\sqrt{s_{\rm NN}} = 5.02$ TeV.
Details of the nuclear structure of $^{\rm 129}$Xe, such as the quadrupole deformation and the nuclear diffuseness, are studied by extensive measurements of anisotropic-flow-related observables in Xe--Xe collisions at a centre-of-mass energy per nucleon pair $\sqrt{s_{_{\mathrm{NN}}}}~=~5.44$ TeV with the ALICE detector at the LHC. The results are compared with those from Pb--Pb collisions at $\sqrt{s_{_{\mathrm{NN}}}}~=~5.02$ TeV for a baseline, given that the $^{\rm 208}$Pb nucleus exhibits a very weak deformation. Furthermore, comprehensive comparisons are performed with a state-of-the-art hybrid model using IP-Glasma+MUSIC+UrQMD. It is found that among various IP-Glasma+MUSIC+UrQMD calculations with different values of nuclear parameters, the one using a nuclear diffuseness parameter of $a_0=0.492$ and a nuclear quadrupole deformation parameter of $β_2=0.207$ provides a better description of the presented flow measurements. These studies represent the first systematic exploration of nuclear structure at TeV energies, utilizing a comprehensive set of anisotropic flow observables. The measurements serve as a critical experimental benchmark for rigorously testing the interplay between nuclear structure inputs and heavy-ion theoretical models.
Charged particle $v_2\{2, \left | \Delta\eta \right | > 1.0\}$ as a function of centrality in Xe$-$Xe and Pb$-$Pb collisions at $\sqrt{s_\mathrm{NN}}$ = 5.44 TeV and $\sqrt{s_\mathrm{NN}}$ = 5.02 TeV, respectively.
Charged particle $v_2\{4\}$ as a function of centrality in Xe$-$Xe and Pb$-$Pb collisions at $\sqrt{s_\mathrm{NN}}$ = 5.44 TeV and $\sqrt{s_\mathrm{NN}}$ = 5.02 TeV, respectively.
Ratio between Xe$-$Xe and Pb$-$Pb charged particle $v_2\{2, \left | \Delta\eta \right | > 1.0\}$ as a function of centrality.
The pseudorapidity ($\eta$) distributions of charged hadrons are measured using data collected at the highest ever nucleon-nucleon center-of-mass energy of $\sqrt{s_\mathrm{NN}}$ = 5.36 TeV for collisions of lead-lead ions. The data were recorded by the CMS experiment at the LHC in 2022 and correspond to an integrated luminosity of 0.30 $\pm$ 0.03 $\mu$b$^{-1}$. Using the CMS silicon pixel detector, the yields of primary charged hadrons produced in the range $\vert\eta\vert$$\lt$ 2.6 are reported. The evolution of the midrapidity particle density as a function of collision centrality is also reported. In the 5% most central collisions, the charged-hadron $\eta$ density in the range $\vert\eta\vert$ $\lt$ 0.5 is found to be 2032 $\pm$ 91 (syst), with negligible statistical uncertainty. This result is consistent with an extrapolation from nucleus-nucleus collision data at lower center-of-mass energies. Comparisons are made to various Monte Carlo event generators and to previous measurements of lead-lead and xenon-xenon collisions at similar collision energies. These new data detail the dependence of particle production on the collision energy, initial collision geometry, and the size of the colliding nuclei.
Charged-hadron $\mathrm{d}N_{\mathrm{ch}}/\mathrm{d}\eta$ distributions in PbPb collisions at 5.36 TeV for events in the 0--80%, 0--5% and 50--55% centrality class.
Charged-hadron $\mathrm{d}N_{\mathrm{ch}}/\mathrm{d}\eta$ in PbPb collisions at 5.36 TeV at midrapidity as a function of event centrality.
Charged-hadron $\mathrm{d}N_{\mathrm{ch}}/\mathrm{d}\eta/2A$ in PbPb collisions at 5.36 TeV at midrapidity as a function of event centrality.
This Letter presents a search for highly ionizing magnetic monopoles in 262$~\mu$b$^{-1}$ of ultraperipheral Pb+Pb collision data at $\sqrt{s_{_\textrm{NN}}}=5.36$ TeV collected by the ATLAS detector at the LHC. A new methodology that exploits the properties of clusters of hits reconstructed in the innermost silicon detector layers is introduced to study highly ionizing particles in heavy-ion data. No significant excess above the background, which is estimated using a data-driven technique, is observed. Using a nonperturbative semiclassical model, upper limits at 95% confidence level are set on the cross-section for pair production of monopoles with a single Dirac magnetic charge in the mass range of 20-150 GeV. The search significantly improves on the previous cross-section limits for production of low-mass monopoles in ultraperipheral Pb+Pb collisions.
Expected and observed cross-section upper limits computed using the CL$_{s}$ method for $|q_{m}| = 1 g_{\textrm{D}}$ and assuming FPA model
Measurements of fiducial and total inclusive cross sections for W and Z boson production are presented in proton-proton collisions at $\sqrt{s}$ = 5.02 and 13 TeV. Electron and muon decay modes ($\ell$ = e or $\mu$) are studied in the data collected with the CMS detector in 2017, in dedicated runs with reduced instantaneous luminosity. The data sets correspond to integrated luminosities of 298 $\pm$ 6 pb$^{-1}$ at 5.02 TeV and 206 $\pm$ 5 pb$^{-1}$ at 13 TeV. Measured values of the products of the total inclusive cross sections and the branching fractions at 5.02 TeV are $\sigma$(pp $\to$ W+X) $\mathcal{B}$(W $\to$$\ell\nu$) = 7300 $\pm$ 10 (stat) $\pm$ 60 (syst) $\pm$ 140 (lumi) pb, and $\sigma$(pp $\to$ Z+X) $\mathcal{B}$(Z $\to$$\ell^+\ell^-$) = 669 $\pm$ 2 (stat) $\pm$ 6 (syst) $\pm$ 13 (lumi) pb for the dilepton invariant mass in the range of 60-120 GeV. The corresponding results at 13 TeV are 20480 $\pm$ 10 (stat) $\pm$ 170 (syst) $\pm$ 470 (lumi) pb and 1952 $\pm$ 4 (stat) $\pm$ 18 (syst) $\pm$ 45 (lumi) pb. The measured values agree with cross section calculations at next-to-next-to-leading-order in perturbative quantum chromodynamics. Fiducial and total inclusive cross sections, ratios of cross sections of W$^+$ and W$^-$ production as well as inclusive W and Z boson production, and ratios of these measurements at 5.02 and 13 TeV are reported.
Distributions of $m_T$ in the $W^{+}$ signal selection for e final states for the pp collisions at $\sqrt{s}=$ 5TeV after the maximum likelihood fit. The EW backgrounds include the contributions from DY, $W\to\tau\nu$, and diboson processes.
Distributions of $m_T$ in the $W^{+}$ signal selection for mu final states for the pp collisions at $\sqrt{s}=$ 5TeV after the maximum likelihood fit. The EW backgrounds include the contributions from DY, $W\to\tau\nu$, and diboson processes.
Distributions of $m_T$ in the $W^{+}$ signal selection for e final states for the pp collisions at $\sqrt{s}=$ 13TeV after the maximum likelihood fit. The EW backgrounds include the contributions from DY, $W\to\tau\nu$, and diboson processes.
The production cross sections of $\mathrm {D^0}$, $\mathrm {D^+}$, and $\mathrm {\Lambda_{c}^{+}}$ hadrons originating from beauty-hadron decays (i.e. non-prompt) were measured for the first time at midrapidity in proton$-$lead (p$-$Pb) collisions at the center-of-mass energy per nucleon pair of $\sqrt{s_{\mathrm{NN}}} = 5.02$ TeV. Nuclear modification factors ($R_{\mathrm {pPb}}$) of non-prompt $\mathrm {D^0}$, $\mathrm {D^+}$, and $\mathrm {\Lambda_{c}^{+}}$ are calculated as a function of the transverse momentum ($p_{\mathrm T}$) to investigate the modification of the momentum spectra measured in p$-$Pb collisions with respect to those measured in proton$-$proton (pp) collisions at the same energy. The $R_{\mathrm {pPb}}$ measurements are compatible with unity and with the measurements in the prompt charm sector, and do not show a significant $p_{\mathrm T}$ dependence. The $p_{\mathrm T}$-integrated cross sections and $p_{\mathrm T}$-integrated $R_{\mathrm {pPb}}$ of non-prompt $\mathrm {D^0}$ and $\mathrm {D^+}$ mesons are also computed by extrapolating the visible cross sections down to $p_{\mathrm T}$ = 0. The non-prompt D-meson $R_{\mathrm {pPb}}$ integrated over $p_{\mathrm T}$ is compatible with unity and with model calculations implementing modification of the parton distribution functions of nucleons bound in nuclei with respect to free nucleons. The non-prompt $\mathrm {\Lambda_{c}^{+}/D^{0}}$ and $\mathrm{D^+/D^0}$ production ratios are computed to investigate hadronisation mechanisms of beauty quarks into mesons and baryons. The measured ratios as a function of $p_{\mathrm T}$ display a similar trend to that measured for charm hadrons in the same collision system.
Non-prompt $\mathrm{D}^0$ $p_\mathrm{{T}}$-differential production cross section $\mathrm{d}^2\sigma/\mathrm{d}p_\mathrm{T}\mathrm{d}y$ in p--Pb collisions at $\sqrt{{s_\mathrm{NN}}}=5.02~\mathrm{{TeV}}$ in the rapidity interval $-0.96 < y_{\mathrm{cms}} < 0.04$.
Non-prompt $\mathrm{D}^+$ $p_\mathrm{{T}}$-differential production cross section $\mathrm{d}^2\sigma/\mathrm{d}p_\mathrm{T}\mathrm{d}y$ in p--Pb collisions at $\sqrt{{s_\mathrm{NN}}}=5.02~\mathrm{{TeV}}$ in the rapidity interval $-0.96 < y_{\mathrm{cms}} < 0.04$.
Non-prompt $\Lambda_{c}^{+}$ $p_\mathrm{{T}}$-differential production cross section $\mathrm{d}^2\sigma/\mathrm{d}p_\mathrm{T}\mathrm{d}y$ in p--Pb collisions at $\sqrt{{s_\mathrm{NN}}}=5.02~\mathrm{{TeV}}$ in the rapidity interval $-0.96 < y_{\mathrm{cms}} < 0.04$.
High-energy nuclear collisions create a quark-gluon plasma, whose initial condition and subsequent expansion vary from event to event, impacting the distribution of the event-wise average transverse momentum ($P([p_{\mathrm{T}}])$). Distinguishing between contributions from fluctuations in the size of the nuclear overlap area (geometrical component) and other sources at fixed size (intrinsic component) presents a challenge. Here, these two components are distinguished by measuring the mean, variance, and skewness of $P([p_{\mathrm{T}}])$ in $^{208}$Pb+$^{208}$Pb and $^{129}$Xe+$^{129}$Xe collisions at $\sqrt{s_{{\mathrm{NN}}}} = 5.02$ and 5.44 TeV, respectively, using the ATLAS detector at the LHC. All observables show distinct changes in behavior in ultra-central collisions, where the geometrical variations are suppressed as the overlap area reaches its maximum. These results demonstrate a new technique to disentangle geometrical and intrinsic fluctuations, enabling constraints on initial condition and properties of the quark-gluon plasma, such as the speed of sound.
Data from Figure 1, panel a, $\left\langle[p_{T}]\right\rangle$ vs $N_{ch}$ for Pb+Pb collisions, 0.5 $ <p_{T}< $ 5 GeV/c, $|\eta|< $ 2.5
Data from Figure 1, panel b, $\left\langle[p_{T}]\right\rangle$ vs $N_{ch}$ for Pb+Pb collisions, 0.5 $ <p_{T}< $ 5 GeV/c, $|\eta|< $ 2.5
Data from Figure 1, panel b, $\left\langle[p_{T}]\right\rangle$ vs $N_{ch}$ for Xe+Xe collisions, 0.5 $ <p_{T}< $ 5 GeV/c, $|\eta|< $ 2.5
This Letter presents the first measurement of event-by-event fluctuations of the net number (difference between the particle and antiparticle multiplicities) of multistrange hadrons $\Xi^-$ and $\overline{\Xi}^+$ and its correlation with the net-kaon number using the data collected by the ALICE Collaboration in pp, p$-$Pb, and Pb$-$Pb collisions at a center-of-mass energy per nucleon pair $\sqrt{s_{\mathrm{NN}}}=5.02\ \mathrm{TeV}$. The statistical hadronization model with a correlation over three units of rapidity between hadrons having the same and opposite strangeness content successfully describes the results. On the other hand, string-fragmentation models that mainly correlate strange hadrons with opposite strange quark content over a small rapidity range fail to describe the data.
Pearson correlation coefficient between the net-$\Xi$ number and net-K number, $\rho_{\Delta\Xi\Delta\mathrm{K}}$, in pp collisions at $\sqrt{s} = 5.02$ TeV
Pearson correlation coefficient between the net-$\Xi$ number and net-K number, $\rho_{\Delta\Xi\Delta\mathrm{K}}$, in p-Pb collisions at $\sqrt{s_{\mathrm{NN}}} = 5.02$ TeV
Pearson correlation coefficient between the net-$\Xi$ number and net-K number, $\rho_{\Delta\Xi\Delta\mathrm{K}}$, in Pb-Pb collisions at $\sqrt{s_{\mathrm{NN}}} = 5.02$ TeV
Measurements of (anti)deuteron and (anti)$^3$He production in the rapidity range $ |y| < $ 0.5 as a function of the transverse momentum and event multiplicity in Xe$-$Xe collisions at a center-of-mass energy per nucleon$-$nucleon pair of $\sqrt{s_{\rm NN}}$ = 5.44 TeV are presented. The coalescence parameters $B_2$ and $B_3$ are measured as a function of the transverse momentum per nucleon. The ratios between (anti)deuteron and (anti)$^3$He yields and those of (anti)protons and pions are reported as a function of the mean charged-particle multiplicity density, and compared with two implementations of the statistical hadronization model and with coalescence predictions. The elliptic flow of (anti)deuterons is measured for the first time in Xe$-$Xe collisions and shows features similar to those already observed in Pb$-$Pb collisions, i.e., the mass ordering at low transverse momentum and the meson$-$baryon grouping at intermediate transverse momentum. The production of nuclei is particularly sensitive to the chemical freeze-out temperature of the system created in the collision, which is extracted from a grand-canonical-ensemble-based thermal fit, performed for the first time including light nuclei along with light-flavor hadrons in Xe$-$Xe collisions. The extracted chemical freeze-out temperature $T_{\rm chem}$ = (154.2 $\pm$ 1.1) MeV in Xe$-$Xe collisions is similar to that observed in Pb$-$Pb collisions and close to the crossover temperature predicted by lattice quantum chromodynamics calculations.
Transverse momentum spectra of 3He nuclei measured in Xe--Xe collisions at centre-of-mass per nucleon-nucleon energy of 5.44 TeV, as shown in Fig. 3 (right panel).
Transverse momentum spectra of deuterons measured in Xe--Xe collisions at centre-of-mass per nucleon-nucleon energy of 5.44 TeV, as shown in Fig. 3 (left panel). Centrality class 0 to 10 percent.
Transverse momentum spectra of deuterons measured in Xe--Xe collisions at centre-of-mass per nucleon-nucleon energy of 5.44 TeV, as shown in Fig. 3 (left panel). Centrality class 10 to 20 percent.
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