Nuclear modification factor of D0 mesons in PbPb collisions at sqrt(s[NN]) = 5.02 TeV

The CMS collaboration Sirunyan, Albert M ; Tumasyan, Armen ; Adam, Wolfgang ; et al.
Phys.Lett.B 782 (2018) 474-496, 2018.
Inspire Record 1616207 DOI 10.17182/hepdata.79053

The transverse momentum ($p_\mathrm{t}$) spectrum of prompt D$^0$ mesons and their antiparticles has been measured via the hadronic decay channels D$^0 \to \mathrm{K}^- \pi^+$ and $\overline{\mathrm{D}}^0 \to \mathrm{K}^+ \pi^-$ in pp and PbPb collisions at a centre-of-mass energy of 5.02 TeV per nucleon pair with the CMS detector at the LHC. The measurement is performed in the D$^0$ meson $p_\mathrm{t}$ range of 2-100 GeV and in the rapidity range of $|y| < $1. The pp (PbPb) dataset used for this analysis corresponds to an integrated luminosity of 27.4 pb$^{-1}$ (530 $\mu$b$^{-1}$). The measured D$^0$ meson $p_\mathrm{t}$ spectrum in pp collisions is well described by perturbative QCD calculations. The nuclear modification factor, comparing D$^0$ meson yields in PbPb and pp collisions, was extracted for both minimum-bias and the 10% most central PbPb interactions. For central events, the D$^0$ meson yield in the PbPb collisions is suppressed by a factor of 5-6 compared to the pp reference in the $p_\mathrm{t}$ range of 6-10 GeV. For D$^0$ mesons in the high-$p_\mathrm{t}$ range of 60-100 GeV, a significantly smaller suppression is observed. The results are also compared to theoretical calculations.

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First measurement of large area jet transverse momentum spectra in heavy-ion collisions

The CMS collaboration Sirunyan, Albert M ; Tumasyan, Armen ; Adam, Wolfgang ; et al.
JHEP 05 (2021) 284, 2021.
Inspire Record 1848440 DOI 10.17182/hepdata.93881

Jet production in lead-lead (PbPb) and proton-proton (pp) collisions at a nucleon-nucleon center-of-mass energy of 5.02 TeV is studied with the CMS detector at the LHC, using PbPb and pp data samples corresponding to integrated luminosities of 404 $\mu$b$^{-1}$ and 27.4 pb$^{-1}$, respectively. Jets with different areas are reconstructed using the anti-$k_\mathrm{T}$ algorithm by varying the distance parameter $R$. The measurements are performed using jets with transverse momenta ($p_\mathrm{T}$) greater than 200 GeV and in a pseudorapidity range of $|\eta|$$\lt$ 2. To reveal the medium modification of the jet spectra in PbPb collisions, the properly normalized ratio of spectra from PbPb and pp data is used to extract jet nuclear modification factors as functions of the PbPb collision centrality, $p_\mathrm{T}$ and, for the first time, as a function of $R$ up to 1.0. For the most central collisions, a strong suppression is observed for high-$p_\mathrm{T}$ jets reconstructed with all distance parameters, implying that a significant amount of jet energy is scattered to large angles. The dependence of jet suppression on $R$ is expected to be sensitive to both the jet energy loss mechanism and the medium response, and so the data are compared to several modern event generators and analytic calculations. The models considered do not fully reproduce the data.

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Version 2
Charged-particle nuclear modification factors in PbPb and pPb collisions at sqrt(s[NN)]=5.02 TeV

The CMS collaboration Khachatryan, Vardan ; Sirunyan, Albert M ; Tumasyan, Armen ; et al.
JHEP 04 (2017) 039, 2017.
Inspire Record 1496050 DOI 10.17182/hepdata.77101

The spectra of charged particles produced within the pseudorapidity window abs(eta) < 1 at sqrt(s[NN]) = 5.02 TeV are measured using 404 inverse microbarns of PbPb and 27.4 inverse picobarns of pp data collected by the CMS detector at the LHC in 2015. The spectra are presented over the transverse momentum ranges spanning 0.5 < pt < 400 GeV in pp and 0.7 < pt < 400 GeV in PbPb collisions. The corresponding nuclear modification factor, R[AA], is measured in bins of collision centrality. The R[AA] in the 5% most central collisions shows a maximal suppression by a factor of 7-8 in the pt region of 6-9 GeV. This dip is followed by an increase, which continues up to the highest pt measured, and approaches unity in the vicinity of pt = 200 GeV. The R[AA] is compared to theoretical predictions and earlier experimental results at lower collision energies. The newly measured pp spectrum is combined with the pPb spectrum previously published by the CMS Collaboration to construct the pPb nuclear modification factor, R[pA], up to 120 GeV. For pt > 20 GeV, R[pA] exhibits weak momentum dependence and shows a moderate enhancement above unity.

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Photoproduction of low-$p_{\rm T}$ J/$\psi$ from peripheral to central Pb$-$Pb collisions at 5.02 TeV

The ALICE collaboration Acharya, Shreyasi ; Adamova, Dagmar ; Adler, Alexander ; et al.
Phys.Lett.B 846 (2023) 137467, 2023.
Inspire Record 2071183 DOI 10.17182/hepdata.134024

An excess of J/$\psi$ yield at very low transverse momentum ($p_{\rm T} < 0.3$ GeV/$c$), originating from coherent photoproduction, is observed in peripheral and semicentral hadronic Pb$-$Pb collisions at a center-of-mass energy per nucleon pair of $\sqrt{s_{\rm NN}} = 5.02$ TeV. The measurement is performed with the ALICE detector via the dimuon decay channel at forward rapidity ($2.5<y<4$). The nuclear modification factor at very low $p_{\rm T}$ and the coherent photoproduction cross section are measured as a function of centrality down to the 10% most central collisions. These results extend the previous study at $\sqrt{s_{\rm NN}} = 2.76$ TeV, confirming the clear excess over hadronic production in the $p_{\rm T}$ range 0$-$0.3 GeV/$c$ and the centrality range 70$-$90%, and establishing an excess with a significance greater than 5$\sigma$ also in the 50$-$70% and 30$-$50% centrality ranges. The results are compared with earlier measurements at $\sqrt{s_{\rm NN}} = 2.76$ TeV and with different theoretical predictions aiming at describing how coherent photoproduction occurs in hadronic interactions with nuclear overlap.

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Measurement of inclusive jet cross-sections in pp and PbPb collisions at sqrt(s[NN])=2.76 TeV

The CMS collaboration Khachatryan, Vardan ; Sirunyan, Albert M ; Tumasyan, Armen ; et al.
Phys.Rev.C 96 (2017) 015202, 2017.
Inspire Record 1487278 DOI 10.17182/hepdata.77601

Inclusive jet spectra from pp and PbPb collisions at a nucleon-nucleon center-of-mass energy of 2.76 TeV, collected with the CMS detector at the LHC, are presented. Jets are reconstructed with three different distance parameters (R = 0.2, 0.3, and 0.4) for transverse momentum (pT) greater than 70 GeV and pseudorapidity abs(eta) < 2. Next-to-leading-order quantum chromodynamic calculations with non-perturbative corrections are found to over-predict jet production cross sections in pp for small distance parameters. The jet nuclear modification factors for PbPb compared to pp collisions, show a steady decrease from peripheral to central events, along with a weak dependence on the jet pT. They are found to be independent of the distance parameter in the measured kinematic range.

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Version 2
J/psi Production in sqrt (s_NN)= 200 GeV Cu+Cu Collisions

The PHENIX collaboration Adare, A. ; Afanasiev, S. ; Aidala, Christine Angela ; et al.
Phys.Rev.Lett. 101 (2008) 122301, 2008.
Inspire Record 776624 DOI 10.17182/hepdata.57327

Yields for J/psi production in Cu+Cu collisions at sqrt (s_NN)= 200 GeV have been measured by the PHENIX experiment over the rapidity range |y| < 2.2 at transverse momenta from 0 to beyond 5 GeV/c. The invariant yield is obtained as a function of rapidity, transverse momentum and collision centrality, and compared with results in p+p and Au+Au collisions at the same energy. The Cu+Cu data provide greatly improved precision over existing Au+Au data for J/psi production in collisions with small to intermediate numbers of participants, providing a key constraint that is needed for disentangling cold and hot nuclear matter effects.

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K$^{*}$(892)$^{\pm}$ resonance production in Pb$-$Pb collisions at $\sqrt{s_{\rm NN}}$ = 5.02 TeV

The ALICE collaboration Acharya, Shreyasi ; Adamova, Dagmar ; Aglieri Rinella, Gianluca ; et al.
Phys.Rev.C 109 (2024) 044902, 2024.
Inspire Record 2692205 DOI 10.17182/hepdata.150017

The production of K$^*$(892)$^\pm$ meson resonance is measured at midrapidity ($|y|<0.5$) in Pb-Pb collisions at $\sqrt{s_{\rm NN}}=5.02$ TeV using the ALICE detector at the LHC. The resonance is reconstructed via its hadronic decay channel K$^*$(892)$^\pm \rightarrow \rm{K^0_S \pi^\pm}$. The transverse momentum distributions are obtained for various centrality intervals in the $p_{\rm T}$ range of 0.4-16 GeV/$c$. The reported measurements of integrated yields, mean transverse momenta, and particle yield ratios are consistent with previous ALICE measurements for K$^*$(892)$^0$. The $p_{\rm T}$-integrated yield ratio 2K$^*$(892)$^\pm$/($\rm{K^+ + K^-}$) in central Pb-Pb collisions shows a significant suppression (9.3$\sigma$) relative to pp collisions. Thermal model calculations overpredict the particle yield ratio. Although both simulations consider the hadronic phase, only HRG-PCE accurately represents the measurements, whereas MUSIC+SMASH tends to overpredict them. These observations, along with the kinetic freeze-out temperatures extracted from the yields of light-flavored hadrons using the HRG-PCE model, indicate a finite hadronic phase lifetime, which increases towards central collisions. The $p_{\rm T}$-differential yield ratios 2K$^*$(892)$^\pm$/($\rm{K^+ + K^-}$) and 2K$^*$(892)$^\pm$/($\rm{\pi^+ + \pi^-}$) are suppressed by up to a factor of five at $p_{\rm T}<2$ GeV/$c$ in central Pb-Pb collisions compared to pp collisions at $\sqrt{s} =$ 5.02 TeV. Both particle ratios and are qualitatively consistent with expectations for rescattering effects in the hadronic phase. The nuclear modification factor shows a smooth evolution with centrality and is below unity at $p_{\rm T}>8$ GeV/$c$, consistent with measurements for other light-flavored hadrons. The smallest values are observed in most central collisions, indicating larger energy loss of partons traversing the dense medium.

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Version 2
Suppression of Upsilon(1S), Upsilon(2S) and Upsilon(3S) production in PbPb collisions at sqrt(s[NN]) = 2.76 TeV

The CMS collaboration Khachatryan, Vardan ; Sirunyan, Albert M ; Tumasyan, Armen ; et al.
Phys.Lett.B 770 (2017) 357-379, 2017.
Inspire Record 1495866 DOI 10.17182/hepdata.77220

The production yields of Upsilon(1S), Upsilon(2S), and Upsilon(3S) quarkonium states are measured through their decays into muon pairs in the CMS detector, in PbPb and pp collisions at the centre-of-mass energy per nucleon pair of 2.76 TeV. The data correspond to integrated luminosities of 166 inverse microbarns and 5.4 inverse picobarns for PbPb and pp collisions, respectively. Differential production cross sections are reported as functions of Upsilon rapidity y up to 2.4, and transverse momentum pT up to 20 GeV/c. A strong centrality-dependent suppression is observed in PbPb relative to pp collisions, by factors of up to approximately 2 and 8, for the Upsilon(1S) and Upsilon(2S) states, respectively. No significant dependence of this suppression is observed as a function of y or pT. The Upsilon(3S) state is not observed in PbPb collisions, which corresponds to a suppression for the centrality-integrated data by at least a factor of approximately 7 at a 95% confidence level. The observed suppression is in agreement with theoretical scenarios modeling the sequential melting of quarkonium states in a quark gluon plasma.

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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.
JHEP 12 (2022) 126, 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 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.

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Version 2
Measurement of prompt $\rm{D_{s}^{+}}$-meson production and azimuthal anisotropy in Pb-Pb collisions at $\sqrt{s_{\rm NN}} = 5.02$ TeV

The ALICE collaboration Acharya, Shreyasi ; Adamova, Dagmar ; Adler, Alexander ; et al.
Phys.Lett.B 827 (2022) 136986, 2022.
Inspire Record 1946931 DOI 10.17182/hepdata.127980

The production yield and angular anisotropy of prompt ${D_s^+}$ mesons were measured as a function of transverse momentum ($p_{ T}$) in Pb-Pb collisions at a centre-of-mass energy per nucleon pair $\sqrt{s_{ NN}} = 5.02$ TeV collected with the ALICE detector at the LHC. ${D_s^+}$ mesons and their charge conjugates were reconstructed at midrapidity ($|y|<0.5$) from their hadronic decay channel ${D_s^+ \to \phi \pi^+}$, with ${\phi \to K^-K^+}$, in the $p_{ T}$ intervals $2<p_{ T}<50$ GeV/$c$ and $2<p_{ T}<36$ GeV/$c$ for the 0-10% and 30-50% centrality intervals. For $p_{ T}>10$ GeV/$c$, the measured ${D_s^+}$-meson nuclear modification factor $R_{ AA}$ is consistent with the one of non-strange D mesons within uncertainties, while at lower $p_{ T}$ a hint for a ${D_s^+}$-meson $R_{ AA}$ larger than that of non-strange D mesons is seen. The enhanced production of ${D_s^+}$ relative to non-strange D mesons is also studied by comparing the $p_{ T}$-dependent ${D_s^+/D^0}$ production yield ratios in Pb-Pb and in pp collisions. The ratio measured in Pb-Pb collisions is found to be on average higher than that in pp collisions in the interval $2<p_{ T} <8$ GeV/$c$ with a significance of 2.3$\sigma$ and 2.4$\sigma$ for the 0-10% and 30-50% centrality intervals. The azimuthal anisotropy coefficient $v_2$ of prompt ${D_s^+}$ mesons was measured in Pb-Pb collisions in the 30-50% centrality interval and is found to be compatible with that of non-strange D mesons. The main features of the measured $R_{ AA}$, ${D_s^+/D^0}$ ratio, and $v_2$ as a function of $p_{ T}$ are described by theoretical calculations of charm-quark transport in a hydrodynamically expanding quark-gluon plasma including hadronisation via charm-quark recombination with light quarks from the medium. The $p_{ T}$-integrated production yield of ${D_s^+}$ mesons is compatible with the prediction of the statistical hadronisation model.

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