Measurements Of Heavy-flavour Production Research Articles

Heavy-flavour production as a function of event activity in pp collisions with the ALICE experiment

Due to their large masses, the production of heavy-flavour quarks can be computed perturbatively, thus providing a powerful tool to test the corresponding QCD calculations. Additionally, measurements of heavy-flavour hadrons are useful to reveal the details of heavy-quark fragmentation in pp collisions at LHC energies. Event-activity-dependent measurements of heavy-flavour production may shed light on the mechanisms of interplay between soft and hard processes. In this contribution, we present recent measurements of the ALICE experiment on charm-hadron production as a function of charged-particle multiplicity in pp collisions at various energies, including the measurements of charm baryon-to-meson production yield ratios. New results of D-meson production as a function of the transverse spherocity of the event, as well as of the transverse event-activity classifier RT, are also presented.

Recent heavy-flavour measurements with ALICE

In this contribution, an overview on the latest results of the ALICE Collaboration on the production of heavy-flavour hadrons in pp and Pb–Pb collision systems will be presented. Due to their large masses, heavy quarks are produced on shorter time scales than the typical QGP formation time, thus they participate to the system evolution and interact with the medium constituents making the heavy-flavour quarks a perfect probe to investigate the QGP properties. Heavy-flavour production measurements in pp collisions are a needed reference for Pb–Pb studies, to study the hadronization mechanisms in small colliding systems and to test perturbative QCD calculations at the LHC energies. The results presented report charm and beauty cross section measurements with an unprecedented precision down to very low momentum. In addition, results on heavy-flavour production highlight the non-universality of heavy-quark fragmentation fractions among different collision systems and energy scales.

Measurements of heavy-flavor production as a function of multiplicity with ALICE at the LHC

In this contribution, the production of heavy-flavor hadrons as a function of multiplicity, via the study of the \mathbf{D}𝐃-meson and heavy-flavor hadron decay leptons self-normalized yields in pp collisions at the center of mass energy \bm{\sqrt{s} = 13}𝐬=13 TeV is discussed. Comparisons are made with similar measurements of J/\bm{\psi}𝛙 at \bm{\sqrt{s} = 13}𝐬=13 TeV and various model calculations. The \mathbf{\Lambda_{c}^{+}/D^{0}}𝚲𝐜+/𝐃0 and \mathbf{D^{+}_{s}/D^{0}}𝐃𝐬+/𝐃0 yield ratios in different multiplicity intervals in pp collisions at \bm{\sqrt{s} = 13}𝐬=13 TeV are also reported. In addition, the ALICE measurement of \mathbf{\Lambda_{c}^{+}}𝚲𝐜+ production in p–Pb collisions at \bm{\sqrt{s_{{NN}}}}𝐬𝐍𝐍 = 5.02 TeV down to transverse momentum (\bm{p_{T}}𝐩𝐓) = 0 GeV/\bm{c}𝐜 is presented. Finally, the nuclear modification factor is shown for open charm hadrons at \bm{\sqrt{s} = 5.02}𝐬=5.02 TeV in p–Pb collisions. Finally, measurements of the elliptic flow of heavy-flavor hadron decay leptons in p–Pb systems are presented, which hint towards a possible collective behaviour in high multiplicity p–Pb collisions.

Latest results on [formula omitted] and D production in pp and Pb-Pb collisions at [formula omitted] with ALICE at the LHC

The measurement of heavy-flavour production is a powerful tool to study the medium formed in high-energy heavy-ion collisions. Produced in hard scattering processes on a timescale shorter than the formation time of the Quark Gluon Plasma (QGP), they experience the whole evolution of the medium interacting with its constituents. The measurement of charm-hadron production allows testing the mechanisms of in-medium parton energy loss. Moreover, the study of charm-baryon production in heavy-ion collisions, and in particular the baryon-to-meson ratio, provides unique information on hadronisation mechanisms, constraining the role of coalescence. In this contribution, the ALICE results on open charmed meson and baryon production in large and small systems will be presented with a focus on the recent measurements of Λc+/D0 and Ds+/D0 ratios in central and peripheral Pb–Pb collisions and on the new results obtained for the same ratios in proton-proton collisions as a function of the charged particle multiplicity. The prospects for the Ξc0 analysis will also be discussed.

Improved constraints on parton distributions using LHCb, ALICE and HERA heavy-flavour measurements and implications for the predictions for prompt atmospheric-neutrino fluxes

The impact of measurements of heavy-flavour production in deep inelastic ep scattering and in pp collisions on parton distribution functions is studied in a QCD analysis at next-to-leading order. Recent combined results of inclusive and heavy-flavour produc- tion cross sections in deep inelastic scattering at HERA are investigated together with heavy-flavour production measurements at the LHC. Differential cross sections of charm- and beauty-hadron production measured by the LHCb collaboration at the centre-of-mass energies of 5, 7 and 13 TeV as well as the recent measurements of the ALICE experiment at the centre-of-mass energies of 5 and 7 TeV are explored. These data impose additional constraints on the gluon and the sea-quark distributions at low partonic fractions x of the proton momentum, down to x ≈ 10−6. The impact of the resulting parton distribution function in the predictions for the prompt atmospheric-neutrino fluxes is studied.

First Measurement of Charm Production in its Fixed-Target Configuration at the LHC.

The first measurement of heavy-flavor production by the LHCb experiment in its fixed-target mode is presented. The production of J/ψ and D^{0} mesons is studied with beams of protons of different energies colliding with gaseous targets of helium and argon with nucleon-nucleon center-of-mass energies of sqrt[s_{NN}]=86.6 and 110.4GeV, respectively. The J/ψ and D^{0} production cross sections in pHe collisions in the rapidity range [2, 4.6] are found to be σ_{J/ψ}=652±33(stat)±42(syst) nb/nucleon and σ_{D^{0}}=80.8±2.4(stat)±6.3(syst) μb/nucleon, where the first uncertainty is statistical and the second is systematic. No evidence for a substantial intrinsic charm content of the nucleon is observed in the large Bjorken-x region.

Measurement of heavy flavor production and azimuthal anisotropy in small and large systems with ATLAS

Heavy-flavor hadron production and collective motion in A+A collisions provide insight into the energy loss mechanism and transport properties of heavy quarks in the QGP. The same measurements in p+A collisions serve as an important baseline for understanding the observations in A+A collisions. For example, detailed studies of heavy-flavor hadron azimuthal anisotropy in p+A collisions may help to address whether the observed long-range “ridge” correlation arises from hard or semi-hard processes, or if it is the result of mechanisms unrelated to the initial hardness scale. These proceedings summarize heavy-flavor hadron production, via their semi-leptonic decay to muons in 2.76 TeV Pb+Pb and pp collisions, non-prompt J/ψ in 5.02 TeV Pb+Pb and pp collisions, and prompt D0 mesons in 8.16 TeV p+Pb collisions using ATLAS detector at the LHC. Azimuthal anisotropy of heavy-flavor hadrons is studied via their decay muons in 2.76 TeV Pb+Pb and 8.16 TeV p+Pb collisions, and via non-prompt J/ψ in 5.02 TeV Pb+Pb collisions. Strong suppression of heavy-flavor hadron production and azimuthal anisotropy are observed in Pb+Pb collisions, while significant azimuthal anisotropy of heavy-flavor muons is observed in p+Pb collisions, without evidence of the modification of their production rates.

Measurement of heavy-flavour production, correlations and jets with ALICE

In this article, recent ALICE measurements of the RAA and v2 of electrons at mid-rapidity (|y|<0.6) and muons at forward rapidity (2.5<y<4), from semi-leptonic decays of heavy-flavour hadrons in Pb–Pb collisions at [see formula in PDF] = 5.02 TeV are shown. The results of D-tagged jet production cross-section in pp collisions at √s =7 TeV are presented. In addition, the azimuthal correlation of D mesons with charged particles in p–Pb collisions at [see formula in PDF] = 5.02 TeV, and electrons from semi-leptonic decays of heavyflavour hadrons with charged particles in p–Pb and Pb–Pb collisions at [see formula in PDF] = 5.02 TeV are reported.

D meson nuclear modification factor and vn harmonics in PbPb collisions at 5.02 TeV with CMS

The measurement of heavy flavor production is a powerful tool to study the properties of the high-density QCD medium created in heavy-ion collisions as heavy quarks are sensitive to the transport properties of the medium and may interact with the QCD matter differently from light quarks. In particular, the comparison between the nuclear modification factors (RAA) of light- and heavy-flavor particles provides insights into the expected flavor dependence of in-medium parton energy loss. Furthermore, azimuthal anisotropy coefficients (vn) of heavy-flavor particles provide insights into the degree of the thermalization of the bulk medium at low pT, and unique information about the path length dependence of heavy quark energy loss at high pT. Using the large pp and PbPb samples collected at 5.02 TeV during the 2015 LHC run, high precision open charm measurements are performed with the CMS detector in a wide transverse momentum range. This allows us to set an important milestone in our understanding of the interactions between charm quarks and the medium. In this talk, the most recent results of the RAA, v2 and v3 of prompt D0 mesons in PbPb collisions at 5.02 TeV are presented and compared to the same results for charged particles (dominated by light flavor hadrons) at the same energy.

D meson nuclear modification factor in PbPb at 5.02 TeV with CMS

The measurement of heavy flavour production is a powerful tool to study the properties of the high-density QCD medium created in heavy-ion collisions as heavy quarks are sensitive to the transport properties of the medium and may interact with the QCD matter differently from light quarks. In particular, the comparison between the nuclear modification factors of light- and heavy-flavour particles provides insights into the expected flavour dependence of in-medium parton energy loss. Using the large statistics proton-proton and PbPb samples collected at 5.02 TeV during the 2015 LHC run, high precision open charm measurements are performed with the CMS detector in a wide transverse momentum range, from few GeV up to approximately 100 GeV. This allows us to set an important milestone in our understanding of energy loss phenomena. In this talk, the most recent results of nuclear modification factor of D0 mesons in PbPb collisions at 5.02 TeV are presented and compared to the charged hadron nuclear modification factor at the same energy.

B physics and Quarkonia in CMS

The heavy-flavor sector offers the opportunity to perform indirect tests of beyond the Standard Model physics through precision measurements and of quantum chromodynamics (QCD) through particle production studies. A review of recent measurements on heavy flavors from the CMS experiment is presented. Results are based on data collected during LHC Run I and Run II and include measurements of heavy flavor production and properties, rare decays, CP violation, exotic and standard quarkonia.

D0 Meson Production in Heavy Ion Collisions in CMS experiment

The measurement of heavy flavour production is a powerful tool to study the properties of the high-density QCD medium created in heavy-ion collisions as heavy quarks are sensitive to the transport properties of the medium and may interact with the QCD matter differently from light quarks. In particular, the comparison between the nuclear modification factors of light and heavy flavoured particles provides insights into the expected flavour dependence of in-medium parton energy loss. With the CMS detector, the D0 meson production is studied in pp and PbPb collisions at 2.76 and 5.02 TeV. In this talk, the nuclear modification factor of D0 meson are presented and compared to the charged hadron nuclear modification factor and theoretical calculations.

Experimental summary for heavy flavor production

Measurements of heavy flavor production in heavy-ion collisions have played an important role in understanding the properties of the quark-gluon plasma created in such collision. Due to their large masses, heavy flavor quarks present unique sensitivity to the kinematics as well as the dynamics of the hot and dense medium. In this article, a selection of recent measurements on heavy flavor production in p+p, p+A and A+A collisions at both RHIC and LHC energies will be presented. The measurements in p+p collisions serve as benchmarks to fundamental theories, and as references to similar studies in A+A collisions where the hot medium effects are present. On the other hand, the measurements in p+A collisions can help to quantify the cold nuclear matter effects which are also in effect in A+A collisions and thus need to be taken into account when interpreting the measurements in heavy-ion collisions. The experimental results from A+A collisions are discussed and compared to theoretical calculations, which can shed lights on the understanding of the quark-gluon plasma.

Open Heavy Flavor Measurements in Heavy Ion Collisions with CMS

The measurement of heavy flavor production is a powerful tool to study the properties of the high-density QCD medium created in heavy-ion collisions as heavy quarks are sensitive to the transport properties of the medium and may interact with the matter differently than light quarks. Heavy flavor jets, non-prompt J/ψ (J/ψ from B-hadron decay) and fully reconstructed B mesons have been studied in PbPb collisions at 2.76 TeV and pPb collisions at 5.02 TeV with CMS. Recently, the nuclear modification factor of prompt D0 mesons has been measured in PbPb collisions at 2.76 TeV with CMS as a function of both transverse momentum and collision centrality. These studies show that prompt D0 production is suppressed in semi-central to central PbPb collisions and the suppression is smaller at high pT. A comparison with the RAA of charged particle and non-prompt J/ψ hints a hierarchy of suppression as a function of flavor.

Measurements of heavy-flavour production in p–Pb collisions with ALICE: Quark Matter 2015

The production of open heavy-flavour particles was studied in p–Pb collisions at sNN=5.02 TeV using the ALICE detector. Three separate observables were used: the hadronic decays of D mesons at mid-rapidity, and semileptonic decays of heavy-flavour hadrons to electrons and muons at mid-rapidity and forward rapidity, respectively. The most recent ALICE measurements of the nuclear modification factor, RpPb, of open charm and beauty are reported, along with the centrality and multiplicity dependence of D-meson production in p–Pb collisions.

Five things you should remember about heavy flavor measurements

Heavy quarks are important tools to study the properties of the hot and dense nuclear matter created in heavy ion collisions. They are produced very early, in the initial interactions with large momentum transfer, and are expected to interact differently from light quarks with the nuclear medium. Measurements of heavy flavor production can provide insights into transport and thermodynamics properties of the created system. In this paper, I give as a brief introduction to the experimental studies of heavy flavor production in relativistic heavy ion collisions and discuss related challenges.

Measurement of heavy-flavour production as a function of multiplicity in pp and p–Pb collisions with ALICE

In these proceedings results are presented from the measurement of open heavy-flavour production as a function of charged-particle multiplicity in pp collisions at $\sqrt {s}$ = 7 TeV and p-Pb collisions at $\sqrt {s_{\rm NN}}$=5.02 TeV recorded with the ALICE detector in 2010 and 2013, respectively. $\rm D^{0}$, $\rm D^{+}$ and $\rm D^{*+}$ mesons are reconstructed from their hadronic decay channels in the central rapidity region, and their production yields are measured in various multiplicity and $p_{\rm T}$ intervals. The per-event yields of $\rm D$ mesons in the various multiplicity intervals, normalized to their multiplicity-integrated value, and their evolution with $p_{\rm T}$ are measured for pp and p-Pb collisions to study the contribution of Multi-Parton Interactions (MPIs) to open charm production in the two systems. The nuclear modification factor of $\rm D$ mesons in p-Pb collisions, defined as the ratio of the $\rm D$-meson yields in p-Pb and pp collisions scaled by the average number of binary collisions $< N_{\rm coll}>$, is discussed in terms of its dependence on the event activity. Several experimental estimators of the event activity are used in order to assess the role of kinematic biases.

Heavy-flavour production and nuclear modification factor in Pb–Pb collisions at sNN=2.76 TeV with ALICE

The measurement of heavy-flavour production and nuclear modification factor in heavy-ion collisions provides insights into the mechanisms of parton energy loss in the hot and dense medium formed in these collisions. ALICE results on heavy-flavour decay electrons and muons and on D mesons are presented.

Heavy Flavor Results from STAR

Heavy flavor quarks are considered to be unique probes of the medium created in high energy heavy ion collisions. These proceedings report selected STAR results from various measurements of heavy flavor production, including J/ψ suppression and collectivity, Υ suppression, ratio of bottom-decay electrons to charm-decay electrons, D meson spectra and charm cross section.

Measurement of heavy-flavor production in Pb—Pb collisions at the LHC with ALICE

A Large Ion Collider Experiment (ALICE) at the Large Hadron Collider (LHC) has been built in order to study the Quark-Gluon Plasma (QGP) created in high-energy nuclear collisions. As heavy-flavor quarks are produced at the early stage of the collision, they serve as sensitive probes for the QGP. The ALICE detector with its capabilities such as particle identification, secondary vertexing and tracking in a high multiplicity environment can address, among other measurements, the heavy-flavor sector in heavy-ion collisions.We present latest results on the measurement of the nuclear modification factor of open heavy-flavors as well as on the measurement of open heavy-flavor azimuthal anisotropy v2 in Pb-Pb collisions at TeV.Open charmed hadrons are reconstructed in the hadronic decay channels D° K−−π+, D+ K−−π+π+, and D*+ D0π+ applying a secondary decay-vertex topology. Complementary measurements are performed by detecting electrons (muons) from semi-leptonic decays of open heavy-flavor hadrons in the central (forward) rapidity region.