Charged-particle angular correlations in XeXe collisions at $\sqrt{s_{_\mathrm{NN}}}=$ 5.44 TeV

The CMS collaboration Sirunyan, Albert M ; Tumasyan, Armen ; Adam, Wolfgang ; et al.
Phys.Rev.C 100 (2019) 044902, 2019.
Inspire Record 1716441 DOI 10.17182/hepdata.88276

Azimuthal correlations of charged particles in xenon-xenon collisions at a center-of-mass energy per nucleon pair of $ \sqrt{s_{_\mathrm{NN}}} =$ 5.44 TeV are studied. The data were collected by the CMS experiment at the LHC with a total integrated luminosity of 3.42 $\mu$b$^{-1}$. The collective motion of the system formed in the collision is parameterized by a Fourier expansion of the azimuthal particle density distribution. The azimuthal anisotropy coefficients $v_{2}$, $v_{3}$, and $v_{4}$ are obtained by the scalar-product, two-particle correlation, and multiparticle correlation methods. Within a hydrodynamic picture, these methods have different sensitivities to non-collective and fluctuation effects. The dependence of the Fourier coefficients on the size of the colliding system is explored by comparing the xenon-xenon results with equivalent lead-lead data. Model calculations that include initial-state fluctuation effects are also compared to the experimental results. The observed angular correlations provide new constraints on the hydrodynamic description of heavy ion collisions.

24 data tables

Elliptic-flow coefficients $v_2$ based on the two-particle correlations technique, as functions of transverse momentum and in bins of centrality. The results correspond to the range $|\eta| < 2.4$.

Elliptic-flow coefficients $v_2$ based on the scalar-product technique, as functions of transverse momentum and in bins of centrality. The results correspond to the range $|\eta| < 0.8$.

Elliptic-flow coefficients $v_2$ based on the four-particle correlations technique, as functions of transverse momentum and in bins of centrality. The results correspond to the range $|\eta| < 2.4$.

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Measurement of beauty production via non-prompt ${\rm D}^{0}$ mesons in Pb-Pb collisions at $\sqrt{s_{\rm NN}}$ = 5.02 TeV

The ALICE collaboration Acharya, Shreyasi ; Adamova, Dagmar ; Adler, Alexander ; et al.
CERN-EP-2022-015, 2022.
Inspire Record 2025044 DOI 10.17182/hepdata.135987

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 hadronization 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.

3 data tables

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.


Measurement of $\psi$(2S) production as a function of charged-particle pseudorapidity density in pp collisions at $\sqrt{s}$ = 13 TeV and p-Pb collisions at $\sqrt{s_{\rm NN}}$ = 8.16 TeV with ALICE at the LHC

The ALICE collaboration
CERN-EP-2022-064, 2022.
Inspire Record 2070433 DOI 10.17182/hepdata.135830

Charmonium production in pp collisions at center-of-mass energy of $\sqrt{s}$ = 13 TeV and p-Pb collisions at center-of-mass energy per nucleon pair of $\sqrt{s_{\rm NN}}$ = 8.16 TeV is studied as a function of charged-particle pseudorapidity density with ALICE. Ground and excited charmonium states (J/$\psi$, $\psi$(2S)) are measured from their dimuon decays in the interval of rapidity in the center-of-mass frame $2.5 < y_{\rm cms} < 4.0$ for pp collisions, and $2.03 < y_{\rm cms} < 3.53$ and $-4.46 < y_{\rm cms} < -2.96$ for p-Pb collisions. The charged-particle pseudorapidity density is measured around midrapidity ($|\eta|<1.0$). In pp collisions, the measured charged-particle multiplicity extends to about six times the average value, while in p-Pb collisions at forward (backward) rapidity a multiplicity corresponding to about three (four) times the average is reached. The $\psi$(2S) yield increases with the charged-particle pseudorapidity density. The ratio of $\psi$(2S) over J/$\psi$ yield does not show a significant multiplicity dependence in either colliding system, suggesting a similar behavior of J/$\psi$ and $\psi$(2S) yields with respect to charged-particle pseudorapidity density. The results are also compared with model calculations.

6 data tables

Ratio of measured PSI(2S) cross section in charged-particle multiplicity intervals and integrated in multiplicity.

Ratio of measured PSI(2S) cross section in charged-particle multiplicity intervals and integrated in multiplicity.

Ratio of measured PSI(2S) cross section in charged-particle multiplicity intervals and integrated in multiplicity.

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Kinematic dependence of azimuthal anisotropies in $p$ $+$ Au, $d$ $+$ Au, $^3$He $+$ Au at $\sqrt{s_{_{NN}}}$ = 200 GeV 

The PHENIX collaboration Acharya, U.A. ; Adare, A. ; Aidala, C. ; et al.
Phys.Rev.C 105 (2022) 024901, 2022.
Inspire Record 2026169 DOI 10.17182/hepdata.132366

There is strong evidence for the formation of small droplets of quark-gluon plasma in $p/d/^{3}$He+Au collisions at the Relativistic Heavy Ion Collider (RHIC) and in $p$+$p$/Pb collisions at the Large Hadron Collider. In particular, the analysis of data at RHIC for different geometries obtained by varying the projectile size and shape has proven insightful. In the present analysis, we find excellent agreement with the previously published PHENIX at RHIC results on elliptical and triangular flow with an independent analysis via the two-particle correlation method, which has quite different systematic uncertainties and an independent code base. In addition, the results are extended to other detector combinations with different kinematic (pseudorapidity) coverage. These results provide additional constraints on contributions from nonflow and longitudinal decorrelations.

59 data tables

$v_2$ vs $p_T$, p+Au at 200 GeV, 0-5% central, BBCS-FVTXS-CNT detector combination

$v_2$ vs $p_T$, d+Au at 200 GeV, 0-5% central, BBCS-FVTXS-CNT detector combination

$v_2$ vs $p_T$, 3He+Au at 200 GeV, 0-5% central, BBCS-FVTXS-CNT detector combination

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Net-proton number fluctuations and the Quantum Chromodynamics critical point

The STAR collaboration Adam, J. ; Adam, J. ; Adamczyk, L. ; et al.
Phys.Rev.Lett. 126 (2021) 092301, 2021.
Inspire Record 1850675 DOI 10.17182/hepdata.101068

Non-monotonic variation with collision energy ($\sqrt{s_{\rm NN}}$) of the moments of the net-baryon number distribution in heavy-ion collisions, related to the correlation length and the susceptibilities of the system, is suggested as a signature for the Quantum Chromodynamics (QCD) critical point. We report the first evidence of a non-monotonic variation in kurtosis times variance of the net-proton number (proxy for net-baryon number) distribution as a function of \rootsnn with 3.1$\sigma$ significance, for head-on (central) gold-on-gold (Au+Au) collisions measured using the STAR detector at RHIC. Data in non-central Au+Au collisions and models of heavy-ion collisions without a critical point show a monotonic variation as a function of $\sqrt{s_{\rm NN}}$.

10 data tables

Event-by-event net-proton multiplicity distributions for central (0-5$\%$) Au+Au collisions from $\sqrt{s_{NN}} = 7.7 - 200 GeV. The distributions are normalised to total number of events. The distributions are not corrected for proton and antiproton detection efficiency.

Cumulants of net-proton distributions in Au+Au collisions for nine energies from $\sqrt{s_{NN}} = 7.7 - 200 GeV for 0-5$\%$ and 70-80$\%$ centrality.

Cumulant ratios C3/C2 and C4/C2 of net-proton distributions in Au+Au collisions for eight energies from $\sqrt{s_{NN}} = 7.7 - 62.4 GeV for 0-5$\%$ centrality. Also given are the derivative of the polynomial fits to the C3/C2 and C4/C2 vs energy at each energy and the Skellam baselines for the ratios.

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Closing in on critical net-baryon fluctuations at LHC energies: cumulants up to third order in Pb$-$Pb collisions

The ALICE collaboration
CERN-EP-2022-111, 2022.
Inspire Record 2092559 DOI 10.17182/hepdata.135800

Fluctuation measurements are important sources of information on the mechanism of particle production at LHC energies. This article reports the first experimental results on third-order cumulants of the net-proton distributions in Pb$-$Pb collisions at a center-of-mass energy $\sqrt{s_{\rm NN}} = 5.02$ TeV recorded by the ALICE detector. The results on the second-order cumulants of net-proton distributions at $\sqrt{s_{\rm NN}} = 2.76$ and $5.02$ TeV are also discussed in view of effects due to the global and local baryon number conservation. The results demonstrate the presence of long-range rapidity correlations between protons and antiprotons. Such correlations originate from the early phase of the collision. The experimental results are compared with HIJING and EPOS model calculations, and the dependence of the fluctuation measurements on the phase-space coverage is examined in the context of lattice quantum chromodynamics (LQCD) and hadron resonance gas (HRG) model estimations. The measured third-order cumulants are consistent with zero within experimental uncertainties of about 4% and are described well by LQCD and HRG predictions.

14 data tables

Delta_eta dependence of Kappa_2(pi+-pi-)/<pi++pi>, momentum range: 0.6 < p < 1.5 GeV/c.

Delta_eta dependence of Kappa_2(K+-K-)/<K++K->, momentum range: 0.6 < p < 1.5 GeV/c.

Delta_eta dependence of Kappa_2(p-pbar)/<p+pbar>, momentum range: 0.6 < p < 1.5 GeV/c.

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Version 2
Observation of $\tau$ lepton pair production in ultraperipheral lead-lead collisions at $\sqrt{s_\mathrm{NN}}$ = 5.02 TeV

The CMS collaboration
CMS-HIN-21-009, 2022.
Inspire Record 2094321 DOI 10.17182/hepdata.129600

We present an observation of photon-photon production of $\tau$ lepton pairs in ultraperipheral lead-lead collisions. The measurement is based on a data sample with an integrated luminosity of 404 $\mu$b$^{-1}$ collected by the CMS experiment at a nucleon-nucleon center-of-mass energy of 5.02 TeV. The $\gamma\gamma\to\tau^+\tau^-$ process is observed for $\tau\tau$ events with a muon and three charged hadrons in the final state. The measured fiducial cross section is $\sigma(\gamma\gamma\to\tau^+\tau^-)$ = 4.8$\pm$ 0.6 (stat) $\pm$ 0.5 (syst) $\mu$b, in agreement with leading-order QED predictions. Using $\sigma(\gamma\gamma\to\tau^+\tau^-)$, we estimate a model-dependent value of the anomalous magnetic moment of the $\tau$ lepton of $a_\tau$ = 0.001$^{+0.055}_{-0.089}$ at a 68% confidence level.

2 data tables

$\gamma\gamma\to\tau\tau$ fiducial cross section

Limits on anomalous magnetic moment of the tau lepton


Pion, Kaon, and (Anti-)Proton Production in U+U Collisions at $\sqrt{s_{NN}}$ = 193 GeV in STAR

The STAR collaboration
2022.
Inspire Record 2129269 DOI 10.17182/hepdata.132660

We present the first measurements of transverse momentum spectra of $\pi^{\pm}$, $K^{\pm}$, $p(\bar{p})$ at midrapidity ($|y| < 0.1$) in U+U collisions at $\sqrt{s_{NN}}$ = 193 GeV with the STAR detector at the Relativistic Heavy Ion Collider (RHIC). The centrality dependence of particle yields, average transverse momenta, particle ratios and kinetic freeze-out parameters are discussed. The results are compared with the published results from Au+Au collisions at \snn = 200 GeV in STAR. The results are also compared to those from A Multi Phase Transport (AMPT) model.

20 data tables

'Identified transverse momentum spectra of $\pi^{+}$ at midrapidity (|y| < 0.1) in U+U collisions at $\sqrt{s_{\rm NN}}$ = 193 GeV'

'Identified transverse momentum spectra of $K^{+}$ at midrapidity (|y| < 0.1) in U+U collisions at $\sqrt{s_{\rm NN}}$ = 193 GeV'

'Identified transverse momentum spectra of p at midrapidity (|y| < 0.1) in U+U collisions at $\sqrt{s_{\rm NN}}$ = 193 GeV'

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Pair invariant mass to isolate background in the search for the chiral magnetic effect in Au+Au collisions at $\sqrt{s_{_{\rm NN}}}$= 200 GeV

The STAR collaboration Abdallah, M.S. ; Adam, J. ; Adamczyk, L. ; et al.
Phys.Rev.C 106 (2022) 034908, 2022.
Inspire Record 1800376 DOI 10.17182/hepdata.95210

Quark interactions with topological gluon configurations can induce local chirality imbalance and parity violation in quantum chromodynamics, which can lead to the chiral magnetic effect (CME) -- an electric charge separation along the strong magnetic field in relativistic heavy-ion collisions. The CME-sensitive azimuthal correlator observable ($\Delta\gamma$) is contaminated by background arising, in part, from resonance decays coupled with elliptic anisotropy ($v_{2}$). We report here differential measurements of the correlator as a function of the pair invariant mass ($m_{\rm inv}$) in 20-50% centrality Au+Au collisions at $\sqrt{s_{_{\rm NN}}}$= 200 GeV by the STAR experiment at RHIC. Strong resonance background contributions to $\Delta\gamma$ are observed. At large $m_{\rm inv}$ where this background is significantly reduced, the $\Delta\gamma$ value is found to be significantly smaller. An event-shape-engineering technique is deployed to determine the $v_{2}$ background shape as a function of $m_{\rm inv}$. We extract a $v_2$-independent and $m_{\rm inv}$-averaged signal $\Delta\gamma_{\rm sig}$ = (0.03 $\pm$ 0.06 $\pm$ 0.08) $\times10^{-4}$, or $(2\pm4\pm5)\%$ of the inclusive $\Delta\gamma(m_{\rm inv}>0.4$ GeV/$c^2$)$ =(1.58 \pm 0.02 \pm 0.02) \times10^{-4}$, within pion $p_{T}$ = 0.2 - 0.8~\gevc and averaged over pseudorapidity ranges of $-1 < \eta < -0.05$ and $0.05 < \eta < 1$. This represents an upper limit of $0.23\times10^{-4}$, or $15\%$ of the inclusive result, at $95\%$ confidence level for the $m_{\rm inv}$-integrated CME contribution.

9 data tables

The $m_{\rm inv}$ dependences of the OS and SS pion pair multiplicities in 20-50$\%$ Au+Au collisions at 200 GeV.

The $m_{\rm inv}$ dependences of the $\gamma_{OS}$, $\gamma_{SS}$ in 20-50$\%$ Au+Au collisions at 200 GeV.

$m_{\rm inv}$ dependences of the relative excess of OS over SS pion pairs in 20-50$\%$ Au+Au collisions at 200 GeV.

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Version 2
Invariant Jet Mass Measurements in $pp$ Collisions at $\sqrt{s} = 200$ GeV at RHIC

The STAR collaboration Abdallah, Mohamed ; Adam, Jaroslav ; Adamczyk, Leszek ; et al.
Phys.Rev.D 104 (2021) 052007, 2021.
Inspire Record 1853218 DOI 10.17182/hepdata.102953

We present the first inclusive measurements of the invariant and SoftDrop jet mass in proton-proton collisions at $\sqrt{s}=200$ GeV at STAR. The measurements are fully corrected for detector effects, and reported differentially in both the jet transverse momentum and jet radius parameter. We compare the measurements to established leading-order Monte Carlo event generators and find that STAR-tuned PYTHIA-6 reproduces the data, while LHC tunes of PYTHIA-8 and HERWIG-7 do not agree with the data, providing further constraints on parameter tuning. Finally, we observe that SoftDrop grooming, for which the contribution of wide-angle non-perturbative radiation is suppressed, shifts the jet mass distributions into closer agreement with the partonic jet mass as determined by both PYTHIA-8 and a next-to-leading-logarithmic accuracy perturbative QCD calculation. These measurements complement recent LHC measurements in a different kinematic region, as well as establish a baseline for future jet mass measurements in heavy-ion collisions at RHIC.

44 data tables

The uncorrected jet mass distribution for $R = 0.4$ anti-$k_{\rm{T}}$ jets with $20 < p_{\rm{T,jet}} < 25$ GeV$/c$.

The uncorrected jet mass distribution for $R = 0.4$ anti-$k_{\rm{T}}$ jets with $20 < p_{\rm{T,jet}} < 25$ GeV$/c$. Updated to correct a small bug that had shifted the jet mass to slightly smaller values.

The uncorrected SoftDrop groomed jet mass distribution for $R = 0.4$ anti-$k_{\rm{T}}$ jets with $20 < p_{\rm{T,jet}} < 25$ GeV$/c$.

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