Ratio Of Production Cross Sections Research Articles

Multiplicity dependence of σψ(2S)/σJ/ψ in pp collisions at s\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ \\sqrt{s} $$\\end{document} = 13 TeV

The ratio of production cross-sections of ψ(2S) over J/ψ mesons as a function of charged-particle multiplicity in proton-proton collisions at a centre-of-mass energy s\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ \\sqrt{s} $$\\end{document} = 13 TeV is measured with a data sample collected by the LHCb detector, corresponding to an integrated luminosity of 658 pb−1. The ratio is measured for both prompt and non-prompt ψ(2S) and J/ψ mesons. When there is an overlap between the rapidity ranges over which multiplicity and charmonia production are measured, a multiplicity-dependent modification of the ratio is observed for prompt mesons. No significant multiplicity dependence is found when the ranges do not overlap. For non-prompt production, the ψ(2S)-to-J/ψ production ratio is roughly independent of multiplicity, irrespective of the rapidity range over which the multiplicity is measured. The results are compared to predictions of the co-mover model and agree well except in the low multiplicity region. The ratio of production cross-sections of ψ(2S) over J/ψ mesons are cross-checked with other measurements in di-lepton channels and found to be compatible.

ψ(2S) Suppression in Pb-Pb Collisions at the LHC

The production of the ψ(2S) charmonium state was measured with ALICE in Pb-Pb collisions at sNN=5.02 TeV, in the dimuon decay channel. A significant signal was observed for the first time at LHC energies down to zero transverse momentum, at forward rapidity (2.5<y<4). The measurement of the ratio of the inclusive production cross sections of the ψ(2S) and J/ψ resonances is reported as a function of the centrality of the collisions and of transverse momentum, in the region pT<12 GeV/c. The results are compared with the corresponding measurements in pp collisions, by forming the double ratio [σψ(2S)/σJ/ψ]Pb−Pb/[σψ(2S)/σJ/ψ]pp. It is found that in Pb-Pb collisions the ψ(2S) is suppressed by a factor of ∼2 with respect to the J/ψ. The ψ(2S) nuclear modification factor RAA was also obtained as a function of both centrality and pT. The results show that the ψ(2S) resonance yield is strongly suppressed in Pb-Pb collisions, by a factor of up to ∼3 with respect to pp. Comparisons of cross section ratios with previous Super Proton Synchrotron findings by the NA50 experiment and of RAA with higher-pT results at LHC energy are also reported. These results and the corresponding comparisons with calculations of transport and statistical models address questions on the presence and properties of charmonium states in the quark-gluon plasma formed in nuclear collisions at the LHC. © 2024 CERN, for the ALICE Collaboration 2024 CERN

Charm production and fragmentation fractions at midrapidity in pp collisions at s\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ \\sqrt{\ extrm{s}} $$\\end{document} = 13 TeV

Measurements of the production cross sections of prompt D0, D+, D*+, Ds+\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ {\ extrm{D}}_{\ extrm{s}}^{+} $$\\end{document}, Λc+\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ {\\Lambda}_{\ extrm{c}}^{+} $$\\end{document}, and Ξc+\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ {\\Xi}_{\ extrm{c}}^{+} $$\\end{document} charm hadrons at midrapidity in proton-proton collisions at s\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ \\sqrt{s} $$\\end{document} = 13 TeV with the ALICE detector are presented. The D-meson cross sections as a function of transverse momentum (pT) are provided with improved precision and granularity. The ratios of pT-differential meson production cross sections based on this publication and on measurements at different rapidity and collision energy provide a constraint on gluon parton distribution functions at low values of Bjorken-x (10−5–10−4). The measurements of Λc+\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ {\\Lambda}_{\ extrm{c}}^{+} $$\\end{document} (Ξc+\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ {\\Xi}_{\ extrm{c}}^{+} $$\\end{document}) baryon production extend the measured pT intervals down to pT = 0(3) GeV/c. These measurements are used to determine the charm-quark fragmentation fractions and the cc¯\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ \ extrm{c}\\overline{\ extrm{c}} $$\\end{document} production cross section at midrapidity (|y| < 0.5) based on the sum of the cross sections of the weakly-decaying ground-state charm hadrons D0, D+, Ds+\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ {\ extrm{D}}_{\ extrm{s}}^{+} $$\\end{document}, Λc+\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ {\\Lambda}_{\ extrm{c}}^{+} $$\\end{document}, Ξc0\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ {\\Xi}_{\ extrm{c}}^0 $$\\end{document} and, for the first time, Ξc+\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ {\\Xi}_{\ extrm{c}}^{+} $$\\end{document}, and of the strongly-decaying J/ψ mesons. The first measurements of Ξc+\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ {\\Xi}_{\ extrm{c}}^{+} $$\\end{document} and Σc0,++\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ {\\Sigma}_{\ extrm{c}}^{0,++} $$\\end{document} fragmentation fractions at midrapidity are also reported. A significantly larger fraction of charm quarks hadronising to baryons is found compared to e+e− and ep collisions. The cc¯\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ \ extrm{c}\\overline{\ extrm{c}} $$\\end{document} production cross section at midrapidity is found to be at the upper bound of state-of-the-art perturbative QCD calculations.

Semi-empirical parameterization of HI/p L-shell X-ray production cross section ratios in Bi for Heavy Ion PIXE

Quantitative analysis of materials from Heavy Ion PIXE spectra remains impeded by the lack of reliable X-ray production cross section (XPCS) data. Although efforts at experimental Heavy Ion induced XPCS measurements still continue, Multiple Ionisation (MI) effects, which are not fully described by theory, render simulations of heavy ion PIXE data unreliable for large Z1/Z2 collisions, especially at low energies. This is also exacerbated by the random selection of projectile-target combinations for measured and reported experimental data available to validate theory. This study explored heavy ion induced X-ray production cross section deviations from those induced by protons at the same ion velocity. This enabled evaluations of the degree to which cross sections are enhanced through MI effects, with the aim of predicting XPCS due to heavy ion impact. The evaluation was carried out through the scaling of experimental heavy ion to theoretical proton cross section ratios (R), which were then used for the interpolation of XPCS in the same target element for ‘missing’ projectiles within the range of evaluation. Here we present measurements of heavy ion induced total L-shell XPCS in Bi, carried out to determine HI/p MI induced deviations due to C, F, Cl and Ti projectiles at an ion velocity range of (0.2–1.0) MeV/nucleon.

{{J}/psi } and {{D}} ^0 production in sqrt{s_{scriptscriptstyle text {NN}}} =68.5,text {GeV} PbNe collisions

The first measurement of {{J}/psi } and {{D}} ^0 production in PbNe collisions by the LHCb experiment in its fixed-target configuration is reported. The production of {{J}/psi } and {{D}} ^0 mesons is studied with a beam of lead ions with an energy of 2.5,text {TeV} per nucleon colliding on gaseous neon targets at rest, corresponding to a nucleon-nucleon centre-of-mass energy of sqrt{s_{scriptscriptstyle text {NN}}} =68.5,text {GeV} . The {{J}/psi }/{{D}} ^0 production cross-section ratio is studied as a function of rapidity, transverse momentum and collision centrality. These data are compared with measurements from ptext {Ne} collisions at the same energy and show no difference in the observed {{J}/psi } suppression trend when comparing ptext {Ne} and PbNe peripheral collisions with PbNe central collisions.

HiggsTools: BSM scalar phenomenology with new versions of HiggsBounds and HiggsSignals

The codes HiggsBounds and HiggsSignals compare model predictions of BSM models with extended scalar sectors to searches for additional scalars and to measurements of the detected Higgs boson at 125GeV. We present a unification and extension of the functionalities provided by both codes into the new HiggsTools framework. The codes have been re-written in modern C++ with native Python and Mathematica interfaces for easy interactive use. We discuss the user interface for providing model predictions, now part of the new sub-library HiggsPredictions, which also provides access to many cross sections and branching ratios for reference models such as the SM. HiggsBounds now implements experimental limits purely through json data files, can better handle clusters of BSM particles of similar masses (even for complicated search topologies), and features an improved handling of mass uncertainties. Moreover, it now contains an extended list of Higgs-boson pair production searches and doubly-charged Higgs boson searches. In HiggsSignals, the treatment of different types of measurements has been unified, both in the χ2 computation and in the data file format used to implement experimental results. Program summaryProgram title:HiggsToolsCPC Library link to program files:https://doi.org/10.17632/b25smy28cj.1Developer's repository link:https://gitlab.com/higgsbounds/higgstoolsLicensing provisions: GPLv3Programming language:C++, Python, MathematicaJournal reference of previous version: P. Bechtle, O. Brein, S. Heinemeyer, G. Weiglein, K.E. Williams, Comput. Phys. Commun. 182 (2011), 2605-2631Does the new version supersede the previous version?: YesReasons for the new version: This version extends the functionality of the previous versions and is re-written in modern C++.Summary of revisions: List of included Higgs-boson searches and Higgs-boson rate measurements has been expanded.Nature of problem: Determine whether a parameter point of a given model is excluded or allowed by LEP and LHC Higgs boson search results, and whether this model point is in agreement with the LHC Higgs-boson rate measurements.Solution method: Exclusion by Higgs boson searches: The most sensitive channel from LEP and LHC searches is determined and subsequently applied to test this parameter point for each Higgs boson of the model under consideration. The test requires as input, model predictions for the Higgs boson masses, branching ratios and ratios of production cross sections with respect to reference values. Agreement with LHC Higgs-boson rate measurements: A χ2 value is calculated based on the available LHC rate measurements. This calculation requires as input model predictions for the Higgs boson(s) at ∼125 GeV.Additional comments including restrictions and unusual features: Assumes that the narrow width approximation is applicable in the model under consideration and that the model does not predict a significant change to the signature of the background processes or the kinematical distributions of the signal cross sections.

Impact of parton energy loss and nPDFs on J/ψ production in proton-nucleus collisions

The impact of parton energy loss and nuclear parton distribution functions (nPDFs) on J/ψ production in proton-nucleus collisions are investigated by means of the E866, LHC and RHIC experimental data. By the recent EPPS21 nPDFs, a leading order phenomenological analysis of J/ψ production cross-section ratios is performed for E866 experimental data with considering the parton energy loss effect following Landau-Pomeranchuk-Migdal (LPM) regime. The gluon transport coefficient qˆg extracted from the E866 data in 0.20<xF<0.65 region is qˆg=0.35±0.01 GeV2/fm with χ2/ndf=1.01, which indicates that the significantly better-constrained gluon distributions provided by EPPS21 contribute to accurately determining the gluon energy loss. It is founded that for E866 data in 0.20<xF<0.65 the depletion induced by cc¯ energy loss is the largest, gluon energy loss is the second, and quark energy loss is the smallest. In addition, it can be seen that for LHC and RHIC experiment the role of nPDFs and gluon energy loss on J/ψ production are both significant, which indicates that operating more precise measurements at LHC and RHIC in the future can facilitate significantly better-constrained gluon energy loss and nPDFs.

Observation of the B_{c}^{+} Meson in Pb-Pb and pp Collisions at sqrt[s_{NN}]=5.02 TeV and Measurement of its Nuclear Modification Factor.

The B_{c}^{+} meson is observed for the first time in heavy ion collisions. Data from the CMS detector are used to study the production of the B_{c}^{+} meson in lead-lead (Pb-Pb) and proton-proton (pp) collisions at a center-of-mass energy per nucleon pair of sqrt[s_{NN}]=5.02 TeV, via the B_{c}^{+}→(J/ψ→μ^{+}μ^{-})μ^{+}ν_{μ} decay. The B_{c}^{+} nuclear modification factor, derived from the Pb-Pb-to-pp ratio of production cross sections, is measured in two bins of the trimuon transverse momentum and of the Pb-Pb collision centrality. The B_{c}^{+} meson is shown to be less suppressed than quarkonia and most of the open heavy-flavor mesons, suggesting that effects of the hot and dense nuclear matter created in heavy ion collisions contribute to its production. This measurement sets forth a promising new probe of the interplay of suppression and enhancement mechanisms in the production of heavy-flavor mesons in the quark-gluon plasma.

Study of dijet events with large rapidity separation in proton-proton collisions at sqrt{s} = 2.76 TeV

The cross sections for inclusive and Mueller-Navelet dijet production are measured as a function of the rapidity separation between the jets in proton-proton collisions at sqrt{s} = 2.76 TeV for jets with transverse momentum pT> 35 GeV and rapidity |y| < 4.7. Various dijet production cross section ratios are also measured. A veto on additional jets with pT> 20 GeV is introduced to improve the sensitivity to the effects of the Balitsky-Fadin-Kuraev-Lipatov (BFKL) evolution. The measurement is compared with the predictions of various Monte Carlo models based on leading-order and next-to-leading-order calculations including the Dokshitzer-Gribov-Lipatov-Altarelli-Parisi leading-logarithm (LL) parton shower as well as the LL BFKL resummation.

Comparison of 3ΛH/4ΛH production cross-section via (K−, π0) reaction at J-PARC

Recent heavy-ion collision experiments reported a surprisingly short lifetime for the hypertriton, which has been recognized as the hypertriton lifetime puzzle. Our J-PARC E73 experiment contributes to solve this puzzle with an independent experimental method by employing 3He(K−, π0) 3ΛH reaction. In this contribution, we will demonstrate our capability to provide 3ΛH binding energy information by deriving the production cross section ratio, σ3ΛH/σ4ΛH. The production cross section data for 3ΛH and 4ΛH are already available as the pilot run of E73 experiment and data analysis is in progress.

Quantitation of the production cross-section and transition probabilities of the L and M X-ray series in the Au(0) and Au(3+) atomic environments using Total-reflection X-ray fluorescence

This work presents the quantitation of the effects that different chemical environments induced in the transition probabilities of their L and M series spectra working in the particular geometrical and analytical conditions imposed by the Total-reflection X-Ray Fluorescence (TXRF) spectrometry. The evaluated chemical environments were metallic Au(0) and chloride Au(3+) phases, with different oxidation states and different crystal field surroundings. Lines Ll, Lα, Lη, Lβ, Lγ and the overlapped Mα and Mβ, named as Mαβ, were evaluated. Transition probabilities and production cross-section ratios were calculated for both gold environments. The absolute transition probabilities were evaluated as the intensity of each line versus the sum of the set of intensities investigated, i.e. Au L and M lines. Achieved results show significant differences between both gold chemical states and environments higher than uncertainties. TXRF has proven to be sensitive to the transition probabilities induced by different atomic environments. Intensity variations with decrements of −7.3% for Lβ line and increments of 96% for Mαβ lines were measured. In parallel, the same phenomenon observed for gold has been observed qualitatively and for the first time by TXRF in three different phases of lead, metallic Pb(0), nitrate Pb(2+) and sulfide Pb(2+). The achieved results corroborate the ability of TXRF to investigate the, different oxidation states, differents crystalline phases, different environments and in a general way, the different chemical surrounding effect. Finally, the existence of a possible enhancement effect in the Au Mαβ line due to a secondary excitation by the presence of Cl Kα secondary excitation was also checked. Results indicate that the observed change of Mαβ intensities between metallic gold and gold chloride are not due to the Cl Kα enhancement effect.

Measurement of nuclear effects on \u03c8(2S) production in p-Pb collisions at sqrt{s_{mathrm{NN}}} = 8.16 TeV

Inclusive ψ(2S) production is measured in p-Pb collisions at the centre-of-mass energy per nucleon-nucleon pair sqrt{s_{mathrm{NN}}} = 8.16 TeV, using the ALICE detector at the CERN LHC. The production of ψ(2S) is studied at forward (2.03 < ycms< 3.53) and backward (−4.46 < ycms< −2.96) centre-of-mass rapidity and for transverse momentum pT< 12 GeV/c via the decay to muon pairs. In this paper, we report the integrated as well as the ycms- and pT-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 pT, 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 [σψ(2S)/σJ/ψ]pPb/[σψ(2S)/σJ/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}}} = 5.02 TeV.

Leading order corrections to the Bethe-Heitler process in the γp→l+l−p reaction

The ratio of di-lepton production cross sections on a proton, using the $\gamma p\rightarrow l^+ l^- p$ process, above and below di-muon production threshold allows to extract the effective lepton-proton interaction, which is required to be identical for electrons and muons if lepton universality is exact. To test for a scenario of broken universality at the percent level, of the size which could explain the different proton charge radii extracted from electron scattering and from muonic hydrogen spectroscopy, we evaluate all one-loop QED corrections to this process, including the full lepton mass dependencies. We furthermore show that two-photon exchange processes with both photons attached to the proton line vanish after averaging over di-lepton angles, and estimate the relatively small radiation off the proton. We compare the full one-loop calculation with a soft-photon approximation of the same order, and present estimates for a planned experiment.

Production of muons from heavy-flavour hadron decays in pp collisions at sqrt{s} = 5.02 TeV

Production cross sections of muons from semi-leptonic decays of charm and beauty hadrons were measured at forward rapidity (2.5 < y < 4) in proton-proton (pp) collisions at a centre-of-mass energy sqrt{s} = 5.02 TeV with the ALICE detector at the CERN LHC. The results were obtained in an extended transverse momentum interval, 2 < pT< 20 GeV/c, and with an improved precision compared to previous measurements performed in the same rapidity interval at centre-of-mass energies sqrt{s} = 2.76 and 7 TeV. The pT- and y-differential production cross sections as well as the pT-differential production cross section ratios between different centre-of-mass energies and different rapidity intervals are described, within experimental and theoretical uncertainties, by predictions based on perturbative QCD.

Heavy quarkonia production at energies available at the CERN Large Hadron Collider and future electron-ion colliding facilities using basis light-front quantization wave functions

We study exclusive charmonium and bottomonium production in ultra-peripheral heavy-ion collisions and electron-ion collisions within the dipole picture. We employ heavy quarkonium light-front wavefunctions obtained within the basis light-front quantization framework, which has some features of the light-front holographic QCD. We focus on comparison with measurements of exclusive charmonium and bottomonium production in ultraperipheral $pp$, $p$Pb and PbPb collisions at LHC and find reasonable agreement with the cross sections. We also discuss the coherent production cross-section ratios of excited states to the ground state for charmonium and bottomonium, which exhibit insensitivity to the dipole model parameters. We show that electron-ion collisions provide an opportunity for a quantitative study of heavy quarkonium structure.

Exploring jet profiles in Pb-Pb collisions at 5.02 TeV with the ALICE detector

In this contribution, we present measurements of inclusive jet production with the ALICE detector in Pb-Pb collisions at sNN=5.02TeV. Production cross sections of charged particle jets and fully reconstructed jets are measured with jet resolution parameters R = 0.2 and 0.3. To quantify the medium induced parton energy loss, jet nuclear modification factors (RAA) are measured by utilizing POWHEG+Pythia8 predictions as reference cross section in pp collisions. We also calculate the ratio of jet production cross sections for jets reconstructed with different cone radii to explore the jet radial profile in Pb-Pb collisions. The ratios of jet cross sections are compared to a pp reference predicted by POWHEG+Pythia8 and in-medium energy loss model prediction by the JEWEL Monte Carlo event generator.

Proton PDFs constraints from measurements using the ATLAS experiment

High-precision measurements of Standard Model (SM) processes provide information on different aspects contributing to the process, such as parton distribution functions (PDFs), and comparisons with the current precision reached theoretically on the calculations of the cross sections of such processes. This document describes ATLAS measurements, performed at different centre-of-mass energies, of vector boson (W and Z) cross sections and cross-section ratios. It also discusses measurements of ratios of Z-boson and top-quark pair production cross sections, which provide important information on the proton PDFs. Finally, a measurement involving the di-lepton decay channel of top-quark pairs at 8 TeV is presented, because of its direct sensitivity to the gluon PDF.

Energy loss effect of incoming gluons from J/ψ production in p-A collisions**Supported by National Natural Science Foundation of China (11405043, 11575052)

The energy loss effect of incoming gluons from J/ψ production in p-A (or d-A) collisions is investigated by means of the E866, RHIC and LHC experimental data. The gluon mean energy loss per unit path length dE/dL = 2.18 ± 0.14 GeV/fm is extracted by fitting the E866 experimental data for J/ψ production cross section ratios RW(Fe)/Be(xF). The obtained result indicates that the incoming gluons lose more energy than the incident quarks. By comparing the theoretical results with E866, RHIC, and LHC experimental data, it is found that the nuclear suppression due to the incident gluon (quark) energy loss reduces (increases) with the increase of the kinematic variable xF (or y). The energy loss effect of incoming gluons plays an important role in the suppression of J/ψ production in a wide energy range from to , and the influence of incident quark energy loss can be ignored for high energies (such as at RHIC and LHC energy).

Measurement of W± and Z-boson production cross sections in pp collisions at s=13 TeV with the ATLAS detector

Measurements of the $W^{\pm} \rightarrow \ell^{\pm} \nu$ and $Z \rightarrow \ell^+ \ell^-$ production cross sections (where $\ell^{\pm}=e^{\pm},\mu^{\pm}$) in proton-proton collisions at $\sqrt{s}=13$ TeV are presented using data recorded by the ATLAS experiment at the Large Hadron Collider, corresponding to a total integrated luminosity of 81 pb$^{-1}$ The total inclusive $W^{\pm}$-boson production cross sections times the single-lepton-flavour branching ratios are $\sigma_{W^+}^{tot}= 11.83 \pm 0.02 (stat) \pm 0.32 (sys) \pm 0.25 (lumi)$ nb and $\sigma_{W^-}^{tot} = 8.79 \pm 0.02 (stat) \pm 0.24 (sys) \pm 0.18 (lumi)$ nb for $W^+$ and $W^-$, respectively. The total inclusive $Z$-boson production cross section times leptonic branching ratio, within the invariant mass window $66 < m_{\ell\ell} < 116$ GeV, is $\sigma_{Z}^{tot} = 1.981 \pm 0.007 (stat) \pm 0.038 (sys) \pm 0.042 (lumi)$ nb. The $W^+$, $W^-$, and $Z$-boson production cross sections and cross-section ratios within a fiducial region defined by the detector acceptance are also measured. The cross-section ratios benefit from significant cancellation of experimental uncertainties, resulting in $\sigma_{W^+}^{fid}/\sigma_{W^-}^{fid} = 1.295 \pm 0.003 (stat) \pm 0.010 (sys)$ and $\sigma_{W^{\pm}}^{fid}/\sigma_{Z}^{fid} = 10.31 \pm 0.04 (stat) \pm 0.20 (sys)$. Theoretical predictions, based on calculations accurate to next-to-next-to-leading order for quantum chromodynamics and to next-to-leading order for electroweak processes and which employ different parton distribution function sets, are compared to these measurements.

Measurement of vector boson plusD*(2010)+meson production inp¯pcollisions ats=1.96 TeV

A measurement of vector boson ($V$) production in conjunction with a $D^{*}(2010)^+$ meson is presented. Using a data sample corresponding to $9.7\, {\rm fb}^{-1}$ of ^Mproton-antiproton collisions at center-of-mass energy $\sqrt{s}=1.96\rm~ TeV$ produced by the Fermilab Tevatron, we reconstruct $V+D^{*+}$ samples with the CDF~II detector. The $D^{*+}$ is fully reconstructed in the $D^{*}(2010)^+ \rightarrow D^{0}(\to K^-\pi^+)\pi^+$ decay mode. This technique is sensitive to the associated production of vector boson plus charm or bottom mesons. We measure the ratio of production cross sections $\sigma(W+D^{*})/\sigma(W)$ = $[1.75\pm 0.13 {\rm (stat)}\pm 0.09 {\rm (syst)}]\% $ and $\sigma(Z+D^{*})/\sigma(Z)$ = $[1.5\pm 0.4 {\rm (stat)} \pm 0.2 {\rm (syst)}]\% $ and perform a differential measurement of $d\sigma(W+D^{*})/dp_T(D^{*})$. Event properties are utilized to determine the fraction of $V+D^{*}(2010)^+$ events originating from different production processes. The results are in agreement with the predictions obtained with the {\sc pythia} program, limiting possible contribution from non-standard-model physics processes.