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Item type:Publication, Production of ω mesons in pp collisions at √s=7TeV(Institute for Ionics, 2020-12-01)Abstract The invariant differential cross section of inclusive $$\omega (782)$$ ω ( 782 ) meson production at midrapidity ( $$|y|<0.5$$ | y | < 0.5 ) in pp collisions at $$\sqrt{s}=7\,\hbox {TeV}$$ s = 7 TeV was measured with the ALICE detector at the LHC over a transverse momentum range of $$2< p_{\mathrm {T}}< 17\,\hbox {GeV}/c$$ 2 < p T < 17 GeV / c . The $$\omega $$ ω meson was reconstructed via its $$\omega \rightarrow \pi ^+\pi ^-\pi ^0$$ ω → π + π - π 0 decay channel. The measured $$\omega $$ ω production cross section is compared to various calculations: PYTHIA 8.2 Monash 2013 describes the data, while PYTHIA 8.2 Tune 4C overestimates the data by about 50%. A recent NLO calculation, which includes a model describing the fragmentation of the whole vector-meson nonet, describes the data within uncertainties below $$6\,\hbox {GeV}/c$$ 6 GeV / c , while it overestimates the data by up to 50% for higher $$p_{\mathrm {T}}$$ p T . The $$\omega /\pi ^0$$ ω / π 0 ratio is in agreement with previous measurements at lower collision energies and the PYTHIA calculations. In addition, the measurement is compatible with transverse mass scaling within the measured $$p_{\mathrm {T}}$$ p T range and the ratio is constant with $$C^{\omega /\pi ^{0}}= 0.67 \pm 0.03 \text {~(stat)~} \pm 0.04 \text {~(sys)~}$$ C ω / π 0 = 0.67 ± 0.03 (stat) ± 0.04 (sys) above a transverse momentum of $$2.5\,\hbox {GeV}/c$$ 2.5 GeV / c . - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Measurement of nuclear effects on ψ(2S) production in p-Pb collisions at √sNN = 8.16 TeV(Springer, 2020-07-01)A bstract Inclusive ψ (2S) production is measured in p-Pb collisions at the centre-of-mass energy per nucleon-nucleon pair $$ \sqrt{s_{\mathrm{NN}}} $$ s NN = 8 . 16 TeV, using the ALICE detector at the CERN LHC. The production of ψ (2S) is studied at forward (2 . 03 < y cms < 3 . 53) and backward ( − 4 . 46 < y cms < − 2 . 96) centre-of-mass rapidity and for transverse momentum p T < 12 GeV/ c via the decay to muon pairs. In this paper, we report the integrated as well as the y cms - and p T -differential inclusive production cross sections. Nuclear effects on ψ (2S) production are studied via the determination of the nuclear modification factor that shows a strong suppression at both forward and backward centre-of-mass rapidities. Comparisons with corresponding results for inclusive J/ ψ show a similar suppression for the two states at forward rapidity (p-going direction), but a stronger suppression for ψ (2S) at backward rapidity (Pb-going direction). As a function of p T , no clear dependence of the nuclear modification factor is found. The relative size of nuclear effects on ψ (2S) production compared to J/ ψ is also studied via the double ratio of production cross sections [ σ ψ (2S) /σ J /ψ ]pPb / [ σ ψ (2S) /σ J /ψ ] pp between p-Pb and pp collisions. The results are compared with theoretical models that include various effects related to the initial and final state of the collision system and also with previous measurements at $$ \sqrt{s_{\mathrm{NN}}} $$ s NN = 5 . 02 TeV.1 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Dielectron production in proton-proton and proton-lead collisions at sNN =5.02 TeV(American Physical Society, 2020-11-25)The first measurements of dielectron production at midrapidity $(\left|{\ensuremath{\eta}}_{\mathrm{e}}\right|<0.8)$ in proton--proton and proton--lead collisions at $\sqrt{{s}_{\mathrm{NN}}}=5.02\phantom{\rule{0.16em}{0ex}}\mathrm{TeV}$ at the LHC are presented. The dielectron cross section is measured with the ALICE detector as a function of the invariant mass ${m}_{\mathrm{ee}}$ and the pair transverse momentum ${p}_{\mathrm{T},\mathrm{ee}}$ in the ranges ${m}_{\mathrm{ee}}<3.5$ $\mathrm{GeV}/{c}^{2}$ and ${p}_{\mathrm{T},\mathrm{ee}}<8$ $\mathrm{GeV}/c$, in both collision systems. In proton--proton collisions, the charm and beauty cross sections are determined at midrapidity from a fit to the data with two different event generators. This complements the existing dielectron measurements performed at $\sqrt{s}=7$ and 13 TeV. The slope of the $\sqrt{s}$ dependence of the three measurements is described by FONLL calculations. The dielectron cross section measured in proton--lead collisions is in agreement, within the current precision, with the expected dielectron production without any nuclear matter effects for ${\mathrm{e}}^{+}{\mathrm{e}}^{\ensuremath{-}}$ pairs from open heavy-flavor hadron decays. For the first time at LHC energies, the dielectron production in proton--lead and proton--proton collisions are directly compared at the same $\sqrt{{s}_{\mathrm{NN}}}$ via the dielectron nuclear modification factor ${R}_{\mathrm{pPb}}$. The measurements are compared to model calculations including cold nuclear matter effects, or additional sources of dielectrons from thermal radiation. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Inclusive J/ψ production at midrapidity in pp collisions at √s = 13 TeV(Springer Science and Business Media Deutschland GmbH, 2021-12-01)We report on the inclusive $$\text {J}/\psi $$ J / ψ production cross section measured at the CERN Large Hadron Collider in proton–proton collisions at a center-of-mass energy $$\sqrt{s}~=~13$$ s = 13 TeV. The $$\text {J}/\psi $$ J / ψ mesons are reconstructed in the $$\text {e}^{+}\text {e}^{-}$$ e + e - decay channel and the measurements are performed at midrapidity ( $$|y|<0.9$$ | y | < 0.9 ) in the transverse-momentum interval $$0 0 < p T < 40 GeV/ $$c$$ c , using a minimum-bias data sample corresponding to an integrated luminosity $$L_{\text {int}} = 32.2~\text {nb}^{-1}$$ L int = 32.2 nb - 1 and an Electromagnetic Calorimeter triggered data sample with $$L_{\text {int}} = 8.3~\mathrm {pb}^{-1}$$ L int = 8.3 pb - 1 . The $$p_{\mathrm{T}}$$ p T -integrated $$\text {J}/\psi $$ J / ψ production cross section at midrapidity, computed using the minimum-bias data sample, is $$\text {d}\sigma /\text {d}y|_{y=0} = 8.97\pm 0.24~(\text {stat})\pm 0.48~(\text {syst})\pm 0.15~(\text {lumi})~\mu \text {b}$$ d σ / d y | y = 0 = 8.97 ± 0.24 ( stat ) ± 0.48 ( syst ) ± 0.15 ( lumi ) μ b . An approximate logarithmic dependence with the collision energy is suggested by these results and available world data, in agreement with model predictions. The integrated and $$p_{\mathrm{T}}$$ p T -differential measurements are compared with measurements in pp collisions at lower energies and with several recent phenomenological calculations based on the non-relativistic QCD and Color Evaporation models.3 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Centrality dependence of J/ψ and ψ(2S) production and nuclear modification in p-Pb collisions at √sNN = 8.16 TeV(Springer Science and Business Media Deutschland GmbH, 2021-02-01)The inclusive production of the J/ψ and ψ(2S) charmonium states is studied as a function of centrality in p-Pb collisions at a centre-of-mass energy per nucleon pair $$ \sqrt{s_{\mathrm{NN}}} $$ s NN = 8.16 TeV at the LHC. The measurement is performed in the dimuon decay channel with the ALICE apparatus in the centre-of-mass rapidity intervals −4.46 < ycms< −2.96 (Pb-going direction) and 2.03 < ycms< 3.53 (p-going direction), down to zero transverse momentum (pT). The J/ψ and ψ(2S) production cross sections are evaluated as a function of the collision centrality, estimated through the energy deposited in the zero degree calorimeter located in the Pb-going direction. The pT-differential J/ψ production cross section is measured at backward and forward rapidity for several centrality classes, together with the corresponding average 〈pT〉 and $$ \left\langle {p}_{\mathrm{T}}^2\right\rangle $$ p T 2 values. The nuclear effects affecting the production of both charmonium states are studied using the nuclear modification factor. In the p-going direction, a suppression of the production of both charmonium states is observed, which seems to increase from peripheral to central collisions. In the Pb-going direction, however, the centrality dependence is different for the two states: the nuclear modification factor of the J/ψ increases from below unity in peripheral collisions to above unity in central collisions, while for the ψ(2S) it stays below or consistent with unity for all centralities with no significant centrality dependence. The results are compared with measurements in p-Pb collisions at $$ \sqrt{s_{\mathrm{NN}}} $$ s NN = 5.02 TeV and no significant dependence on the energy of the collision is observed. Finally, the results are compared with theoretical models implementing various nuclear matter effects. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Measurement of K⁎(892)± production in inelastic pp collisions at the LHC(Elsevier B.V., 2022-05-10)The first results on K⁎(892)± resonance production in inelastic pp collisions at LHC energies of s=5.02, 8, and 13 TeV are presented. The K⁎(892)± has been reconstructed via its hadronic decay channel K⁎(892)→±KS0+π± with the ALICE detector. Measurements of transverse momentum distributions, pT-integrated yields, and mean transverse momenta for charged K⁎(892) are found to be consistent with previous ALICE measurements for neutral K⁎(892) within uncertainties. For pT>1 GeV/c the K⁎(892)± transverse momentum spectra become harder with increasing centre-of-mass energy from 5.02 to 13 TeV, similar to what previously observed for charged kaons and pions. For pT<1 GeV/c the K⁎(892)± yield does not evolve significantly and the abundance of K⁎(892)± relative to K is rather independent of the collision energy. The transverse momentum spectra, measured for K⁎(892)± at midrapidity in the interval 0 < pT<15 GeV/c, are not well described by predictions of different versions of PYTHIA 6, PYTHIA 8 and EPOS-LHC event generators. These generators reproduce the measured pT-integrated K⁎±/K ratios and describe well the momentum dependence for pT<2 GeV/c.