High-momentum two-particle correlations are a useful tool for studying jet-quenching effects in the quark-gluon plasma. Angular correlations between neutral-pion triggers and charged hadrons with transverse momenta in the range 4--12~GeV/$c$ and 0.5--7~GeV/$c$, respectively, have been measured by the PHENIX experiment in 2014 for Au$+$Au collisions at $\sqrt{s_{_{NN}}}=200$~GeV. Suppression is observed in the yield of high-momentum jet fragments opposite the trigger particle, which indicates jet suppression stemming from in-medium partonic energy loss, while enhancement is observed for low-momentum particles. The ratio and differences between the yield in Au$+$Au collisions and $p$$+$$p$ collisions, $I_{AA}$ and $\Delta_{AA}$, as a function of the trigger-hadron azimuthal separation, $\Delta\phi$, are measured for the first time at the Relativistic Heavy Ion Collider. These results better quantify how the yield of low-$p_T$ associated hadrons is enhanced at wide angle, which is crucial for studying energy loss as well as medium-response effects.
Per-trigger jet-pair yield as a function of $\Delta\phi$ for selected $\pi^0$ trigger and charged-hadron-associated $p_T$ combinations (${{p_{T,\pi^0}} \otimes p_{T,h}}$) in Au$+$Au collisions. Systematic uncertainties for background subtraction and global scale uncertainties are given.
Integrated away-side $I_{AA}$ as a function of $p_T^h$. Systematic uncertainties for background subtraction and global scale uncertainties are given.
Differential away-side a function of Deltaphi 0%-20% collisions. Systematic uncertainties for background subtraction and global scale uncertainties are given.
Weakly interacting massive particles (WIMPs) may interact with a virtual pion that is exchanged between nucleons. This interaction channel is important to consider in models where the spin-independent isoscalar channel is suppressed. Using data from the first science run of the LUX-ZEPLIN dark matter experiment, containing 60 live days of data in a 5.5~tonne fiducial mass of liquid xenon, we report the results on a search for WIMP-pion interactions. We observe no significant excess and set an upper limit of $1.5\times10^{-46}$~cm$^2$ at a 90% confidence level for a WIMP mass of 33~GeV/c$^2$ for this interaction.
WIMP-Pion interaction cross section at the 90% CL
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
First measurements of hadron(h)$-\Lambda$ azimuthal angular correlations in p$-$Pb collisions at $\sqrt{s_{\rm NN}}$ = 5.02 TeV using the ALICE detector at the Large Hadron Collider are presented. These correlations are used to separate the production of associated $\Lambda$ baryons into three different kinematic regions, namely those produced in the direction of the trigger particle (near-side), those produced in the opposite direction (away-side), and those whose production is uncorrelated with the jet axis (underlying event). The per-trigger associated $\Lambda$ yields in these regions are extracted, along with the near- and away-side azimuthal peak widths, and the results are studied as a function of associated particle $p_{\rm T}$ and event multiplicity. Comparisons with the DPMJET event generator and previous measurements of the $\phi(1020)$ meson are also made. The final results indicate that strangeness production in the highest multiplicity p$-$Pb collisions is enhanced relative to low multiplicity collisions in both the jet-like regions and the underlying event. The production of $\Lambda$ relative to charged hadrons is also enhanced in the underlying event when compared to the jet-like regions. Additionally, the results hint that strange quark production in the away-side of the jet is modified by soft interactions with the underlying event.
Azimuthal distribution of the per-trigger h-$\Lambda$ yield with trigger transverse momentum between 4 and 8 GeV/c and associated transverse momentum between 1.5 and 2.5 GeV/c for 0-20% multiplicity class p-Pb collisions
Azimuthal distribution of the per-trigger h-$\Lambda$ yield with trigger transverse momentum between 4 and 8 GeV/c and associated transverse momentum between 1.5 and 2.5 GeV/c for 20-50% multiplicity class p-Pb collisions
Azimuthal distribution of the per-trigger h-$\Lambda$ yield with trigger transverse momentum between 4 and 8 GeV/c and associated transverse momentum between 1.5 and 2.5 GeV/c for 50-80% multiplicity class p-Pb collisions
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.
The first measurement of $_{\Lambda}^{3}\mathrm{H}$ and $^3_ {\overline{\Lambda}}\overline{\mathrm{H}}$ differential production with respect to transverse momentum and centrality in Pb$-$Pb collisions at $\sqrt{s_{\mathrm{NN}}}=5.02$~TeV is presented. The $_{\Lambda}^{3}\mathrm{H}$ has been reconstructed via its two-charged-body decay channel, i.e., $_{\Lambda}^{3}\mathrm{H} \rightarrow {}^{3}\mathrm{He} + \pi^{-}$. A Blast-Wave model fit of the $p_{\rm T}$-differential spectra of all nuclear species measured by the ALICE collaboration suggests that the $_{\Lambda}^{3}\mathrm{H}$ kinetic freeze-out surface is consistent with that of other nuclei. The ratio between the integrated yields of $_{\Lambda}^{3}\mathrm{H}$ and $^3\mathrm{He}$ is compared to predictions from the statistical hadronisation model and the coalescence model, with the latter being favoured by the presented measurements.
Transverse momentum distributions of (anti)hypertriton in 0-10% V0M centrality class
Transverse momentum distributions of (anti)hypertriton in 10-30% V0M centrality class
Transverse momentum distributions of (anti)hypertriton in 30-50% V0M centrality class
A comprehensive study of the local and nonlocal amplitudes contributing to the decay $B^0\rightarrow K^{*0}(\to K^+\pi^-) \mu^+\mu^-$ is performed by analysing the phase-space distribution of the decay products. The analysis is based on $pp$ collision data corresponding to an integrated luminosity of 8.4fb$^{-1}$ collected by the LHCb experiment. This measurement employs for the first time a model of both one-particle and two-particle nonlocal amplitudes, and utilises the complete dimuon mass spectrum without any veto regions around the narrow charmonium resonances. In this way it is possible to explicitly isolate the local and nonlocal contributions and capture the interference between them. The results show that interference with nonlocal contributions, although larger than predicted, only has a minor impact on the Wilson Coefficients determined from the fit to the data. For the local contributions, the Wilson Coefficient $C_9$, responsible for vector dimuon currents, exhibits a $2.1\sigma$ deviation from the Standard Model expectation. The Wilson Coefficients $C_{10}$, $C_{9}'$ and $C_{10}'$ are all in better agreement than $C_{9}$ with the Standard Model and the global significance is at the level of $1.5\sigma$. The model used also accounts for nonlocal contributions from $B^{0}\to K^{*0}\left[\tau^+\tau^-\to \mu^+\mu^-\right]$ rescattering, resulting in the first direct measurement of the $b s\tau\tau$ vector effective-coupling $C_{9\tau}$.
Signal parameter results. See Table 1 in README.pdf in the attached resources for an explicit mapping between text-based parameter names and their symbolic representations in the main paper.
Total covariance matrix including both statistical and systematic effects. See Sec. 5 in the main paper for a description of the dominant systematic uncertainties. See Table 1 in README.pdf in the attached resources for an explicit mapping between text-based parameter names and their symbolic representations in the main paper.
Statistical covariance matrix. See Table 1 in README.pdf in the attached resources for an explicit mapping between text-based parameter names and their symbolic representations in the main paper.
The transverse momentum ($p_{\rm T}$) differential production cross section of the promptly produced charm-strange baryon $\Xi_{\rm c}^{0}$ (and its charge conjugate $\overline{\Xi_{\rm c}^{0}}$) is measured at midrapidity via its hadronic decay into ${\rm \pi^{+}}\Xi^{-}$ in p$-$Pb collisions at a centre-of-mass energy per nucleon$-$nucleon collision $\sqrt{s_{\mathrm{NN}}}~=~5.02$ TeV with the ALICE detector at the LHC. The $\Xi_{\rm c}^{0}$ nuclear modification factor ($R_{\rm pPb}$), calculated from the cross sections in pp and p$-$Pb collisions, is presented and compared with the $R_{\rm pPb}$ of $\Lambda_{\rm c}^{+}$ baryons. The ratios between the $p_{\rm T}$-differential production cross section of $\Xi_{\rm c}^{0}$ baryons and those of $\mathrm {D^0}$ mesons and $\Lambda_{\rm c}^{+}$ baryons are also reported and compared with results at forward and backward rapidity from the LHCb Collaboration. The measurements of the production cross section of prompt $\Xi^0_{\rm c}$ baryons are compared with a model based on perturbative QCD calculations of charm-quark production cross sections, which includes only cold nuclear matter effects in p$-$Pb collisions, and underestimates the measurement by a factor of about 50. This discrepancy is reduced when the data is compared with a model that includes string formation beyond leading-colour approximation or in which hadronisation is implemented via quark coalescence. The $p_{\rm T}$-integrated cross section of prompt $\Xi^0_{\rm c}$-baryon production at midrapidity extrapolated down to $p_{\rm T}$ = 0 is also reported. These measurements offer insights and constraints for theoretical calculations of the hadronisation process. Additionally, they provide inputs for the calculation of the charm production cross section in p$-$Pb collisions at midrapidity.
Prompt $\Xi_\mathrm{c}^0$ productions cross-section as a function of $p_\mathrm{T}$ in p–Pb collisions at $\sqrt{s_\mathrm{NN}} = 5.02$ TeV.
$\Xi_\mathrm{c}^0~R_\mathrm{pPb}$ as a function of $p_\mathrm{T}$ in p–Pb collisions at $\sqrt{s_\mathrm{NN}} = 5.02$ TeV.
$\Xi_\mathrm{c}^0/\mathrm{D}^0$ ratio as a function of $p_\mathrm{T}$ in p–Pb collisions at $\sqrt{s_\mathrm{NN}} = 5.02$ TeV.
This Letter presents the first measurement of the impact-parameter dependent angular anisotropy in the decay of coherently photoproduced $\rho^0$ mesons. The $\rho^0$ mesons are reconstructed through their decay into pion pairs. The measured anisotropy corresponds to the amplitude of the $\cos(2\phi)$ modulation, where $\phi$ is the angle between the two vectors formed by the sum and the difference of the transverse momenta of the pions, respectively. The measurement was performed by the ALICE Collaboration at the LHC using data from ultraperipheral Pb$-$Pb collisions at a center-of-mass energy of $\sqrt{s_{\mathrm{NN}}}~=~5.02$ TeV per nucleon pair. Different impact-parameter regions are selected by classifying the events in nuclear-breakup classes. The amplitude of the $\cos(2\phi)$ modulation is found to increase by about one order of magnitude from large to small impact parameters. Theoretical calculations describe the measured $\cos(2\phi)$ anisotropy and its impact-parameter dependence as the result of a quantum interference effect at the femtometer scale, arising from the ambiguity regarding which of the nuclei is the photon source in the interaction.
Amplitudes of the $\cos(2\phi)$ modulation of the $ρ^0$ yield in ultra-peripheral Pb--Pb collisions at $\sqrt{s_{NN}}$ = 5.02 TeV in all neutron classes.
This work aims to differentiate strangeness produced from hard processes (jet-like) and softer processes (underlying event) by measuring the angular correlation between a high-momentum trigger hadron (h) acting as a jet-proxy and a produced strange hadron ($\phi(1020)$ meson). Measuring h$-\phi$ correlations at midrapidity in p$-$Pb collisions at $\sqrt{s_{\rm NN}}$ = 5.02 TeV as a function of event multiplicity provides insight into the microscopic origin of strangeness enhancement in small collision systems. The jet-like and the underlying-event-like strangeness production are investigated as a function of event multiplicity. They are also compared between a lower and higher momentum region. The evolutions of the per-trigger yields within the near-side (aligned with the trigger hadron) and away-side (in the opposite direction of the trigger hadron) jets are studied separately, allowing for the characterization of two distinct jet-like production regimes. Furthermore, the h$-\phi$ correlations within the underlying event give access to a production regime dominated by soft production processes, which can be compared directly to the in-jet production. Comparisons between h$-\phi$ and dihadron correlations show that the observed strangeness enhancement is largely driven by the underlying event, where the $\phi/\mathrm{h}$ ratio is significantly larger than within the jet regions. As multiplicity increases, the fraction of the total $\phi(1020)$ yield coming from jets decreases compared to the underlying event production, leading to high-multiplicity events being dominated by the increased strangeness production from the underlying event.
Pet-trigger h--$\phi$ and h--h pair yields within the near and away-side jet peaks as a function of charged particle multiplicity in p--Pb collisions at $\sqrt{s_{\mathrm{NN}}}$ = 5.02 TeV in the pseudorapidity region $|\eta|<0.8$. Pairs consist of a trigger hadron in the range $4.0 < p_{\mathrm{T, trig}} < 8.0 \mathrm{~GeV}/c$ and an associated $\phi$(1020) (h) in the range $1.5 < p_{\mathrm{T, assoc}} < 2.5 \mathrm{~GeV}/c$.
Pet-trigger h--$\phi$ and h--h pair yields within the near and away-side jet peaks as a function of charged particle multiplicity in p--Pb collisions at $\sqrt{s_{\mathrm{NN}}}$ = 5.02 TeV in the pseudorapidity region $|\eta|<0.8$. Pairs consist of a trigger hadron in the range $4.0 < p_{\mathrm{T, trig}} < 8.0 \mathrm{~GeV}/c$ and an associated $\phi$(1020) (h) in the range $2.5 < p_{\mathrm{T, assoc}} < 4.0 \mathrm{~GeV}/c$.
Pairwise (h--$\phi$)/(h--h) ratio vs $\langle N_{\mathrm{ch}} \rangle$ for the lower associated momentum range, $1.5 < p_{\mathrm{T, assoc}} < 2.5 \mathrm{~GeV}/c$ in p--Pb collisions at $\sqrt{s_{\mathrm{NN}}}$ = 5.02 TeV in the pseudorapidity region $|\eta|<0.8$.
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