Charm Production Cross Section Research Articles

Constraining hadronization processes with charmed baryons in pp and p–Pb collisions with ALICE

The latest measurements of D0, D+ and Ds+ mesons with the final measurements of Λc+,Ξc0,+, Σc0,++, and the first measurement of Ωcc baryons performed with the ALICE detector at midrapidity in pp collisions √S = 5.02 TeV and √S = 13 TeV are presented. Furthermore, the recent Λc+/D0 yield ratio, measured down to pT = 0 in p-Pb collisions are discussed. Finally, the first measurements of charm fragmentation fractions and charm production cross section at midrapidity per unit of rapidity are shown for both pp and p-Pb collisions using all measured charm ground state hadrons.

Track and vertex reconstruction using moving emulsion blocks and a silicon pixel tracker for particles induced by 400 GeV/c protons on a thick target

The SHiP-charm experiment is designed to measure the charm production cross section, including cascade production, of 400 GeV/c protons hitting a thick, SHiP-like target. For the detection of production and decay of heavy charmed particles, emulsion films are employed in a multilayered moving target, forming an emulsion cloud chamber. While the emulsion films provide excellent spatial resolution they do not provide timing information, integrate all events, and quickly get saturated. For the charm measurement the emulsion target is thus moving at a constant speed during data-taking. A first optimization run at the CERN SPS has been performed in 2018, with the purpose to develop the required analysis tools and to fine-tune the detector layout. We report on the experiment design, track reconstruction in the pixel tracker and the track matching with the moving emulsion detector.

Charm production and hadronisation in ALICE

Heavy-flavour production is an active and highly interesting field of research. Since charm and beauty quarks are predominantly produced in the hard scattering process of colliding nuclei, they serve as unique probes to study the quark-gluon plasma in \PbPb{} collisions. In addition, recent investigations of hadronisation mechanisms have revealed interesting and unexpected features when comparing measurements in \ee{} and in hadronic collisions as in \pp{}, \pPb{} and \PbPb{}. This article summarises the latest results of charm production measured by the ALICE Collaboration. For the first time, \Scnullpp{} and \Onull{} were measured in hadronic collisions and production measurements of the \Lc{} and \Xcnull{} are now included in the computation of the charm production cross section.

Charm-quark fragmentation fractions and production cross section at midrapidity in pp collisions at the LHC

Recent $p_{\rm T}$-integrated cross section measurements of the ground-state charm mesons and baryons, D$^{\rm 0}$, D$^+$, D$_{\rm s}^{+}$, $\Lambda_{\rm c}^{+}$, and $\Xi_{\rm c}^0$, are used to evaluate the charm fragmentation fractions and production cross section per unit of rapidity at midrapidity ($|y|<0.5$), in pp collisions at $\sqrt{s} = 5.02$ TeV at the LHC. The latter is ${\rm d} \sigma^{\rm c \overline{c}}/{\rm d} y|_{|y| < 0.5}$ =1165 $\pm 44(\rm{stat})^{+134}_{-101}(\rm{syst})$ $\mu b$. These measurements were obtained for the first time in hadronic collisions at the LHC including the charm baryon states, recently measured by ALICE at midrapidity. The charm fragmentation fractions differ significantly from the values measured in e$^+$e$^-$ and ep collisions, providing evidence of the dependence of the parton-to-hadron fragmentation fractions on the collision system, indicating that the assumption of their universality is not supported by the measured cross sections. An increase of a factor of about 3.3 for the fragmentation fraction for the $\Lambda_{\rm c}^{+}$ with a significance of $5\,\sigma$ between the values obtained in pp collisions and those obtained in e$^+$e$^-$ (ep) collisions is reported. The fragmentation fraction for the $\Xi_{\rm c}^0$ was obtained for the first time in any collision system. The measured fragmentation fractions were used to update the $\rm c \overline{c}$ cross sections per unit of rapidity at $|y|<0.5$ at $\sqrt{s} = 2.76$ and 7 TeV, which are about 40% higher than the previously published results. The data were compared with perturbative-QCD calculations and lie at the upper edge of the theoretical bands.

$$X(3872)$$transport in heavy-ion collisions

AbstractThe production of the $$X(3872)$$ X ( 3872 ) particle in heavy-ion collisions has been contemplated as an alternative probe of its internal structure. To investigate this conjecture, we perform transport calculations of the $$X(3872)$$ X ( 3872 ) through the fireball formed in nuclear collisions at the LHC. Within a kinetic-rate equation approach as previously used for charmonia, the formation and dissociation of the $$X(3872)$$ X ( 3872 ) is controlled by two transport parameters, i.e., its inelastic reaction rate and thermal-equilibrium limit in the evolving hot QCD medium. While the equilibrium limit is controlled by the charm production cross section in primordial nucleon-nucleon collisions (together with the spectra of charm states in the medium), the structure information is encoded in the reaction rate. We study how different scenarios for the rate affect the centrality dependence and transverse-momentum ($$p_T$$ p T ) spectra of the $$X(3872)$$ X ( 3872 ) . Larger reaction rates associated with the loosely bound molecule structure imply that it is formed later in the fireball evolution than the tetraquark and thus its final yields are generally smaller by around a factor of two, which is qualitatively different from most coalescence model calculations to date. The $$p_T$$ p T spectra provide further information as the later decoupling time within the molecular scenario leads to harder spectra caused by the blue-shift from the expanding fireball.

On the Dominant Role of Charm Production in the Forward Kinematic Region According to Cosmic-Ray Experiments

A phenomenon of abnormally weak absorption of very-high-energy cosmic-ray hadrons in lead is discussed. This phenomenon was first observed in Tien-Shan high-altitude experiments in hadronic cores of extensive air showers and has encouraged to introduce the hypothesis of a so-called long-flying or penetrating cosmic-ray component. A similar effect was detected later with deep uniform lead X-ray emulsion chambers (XREC) at the Pamirs. Experiments, which are sensitive to the production of charmed hadrons in the forward kinematic region (xLab ≳ 0.1), have been carried out at the Tien-Shan and Pamirs with exposing two-storey XRECs with large air gaps to prove explanation of the experimental results with high charm production cross section $${\sigma _{pp \to c\bar c}} \sim 8$$ at xLab ≳ 0.1 at ⟨ELab⟩ ∼ 75 TeV. This $${\sigma _{pp \to c\bar c}}$$ value makes it possible to reproduce the experimental hadron-absorption curve observed with XRECs, including curve’s bending at a depth of ∼70 c.u.

Charm and Beauty Production Cross-Section Measurements in Deep Inelastic Electron-Proton Scattering at HERA

The open charm and beauty production cross-sections in the deep inelastic ep scattering (DIS) at HERA from the H1 and ZEUS Collaborations are combined. Reduced cross-sections are obtained in the kinematic range of negative four-momentum transfer squared of a photon 2.5≤ Q2 ≤2000 GeV2 and the Bjorken scaling variable 3×10¬5 ≤ xBj ≤5×10¬2. The different charm- and beauty-tagging methods are used for the heavy-flavor production study in DIS. The combined method accounts for the correlations of systematic uncertainties, as well as statistical uncertainties among the different datasets. Perturbative QCD (pQCD) calculations are compared to the measured combined data. A NLO QCD analysis is performed using these data together with the combined inclusive deep inelastic scattering cross-sections from HERA. The running charm- and beauty-quark masses are determined as mc(mc) = 1,290+0,046−0,041(exp /fit)+0,062−0,014(model)+0,03−0,031(parametrization) GeV and mb(mb) = 4,049+0,104−0,109(exp /fit)+0,090−0,032(model)+0,001−0,031(parametrization) GeV.

Rescattering effects in antiproton-induced exclusive J/$ \psi$ and $ \psi^{{\prime}}_{}$ production on the deuteron

On the basis of the generalized eikonal approximation we study the exclusive reactions $\bar p d \to J/\psi\, n$ and $\bar p d \to \psi^\prime\, n$ in vicinity of the thresholds for charmonium production on a free proton target. It is shown that the rescattering of the incoming antiproton and outgoing charmonium on the spectator neutron leads to a depletion of the charmonium production at low- and to an enhancement at high transverse momenta. This is in qualitative agreement with previous studies of hard proton knockout in proton-deuteron collisions. We analyze different physical sources of uncertainty which may influence the extraction of the total charmonium-neutron cross section. The color transparency effect for the incoming $\bar p$ largely compensates the influence of charmonium rescattering both at low and high transverse momenta. Different choices of the deuteron wave function lead to significant uncertainties at high transverse momenta. As an outcome of the calculations of charmonium production, we also provide predictions on the production of open charm hadrons due to the dissociation of the charmonium on the neutron. It is shown that the open charm production cross section is proportional to the total charmonium-nucleon cross section and quite stable with respect to the variation of other parameters of the model. We thus suggest that open charm channels are most suited for future studies of charmonium-nucleon interactions at PANDA with a deuteron target.

Combination and QCD Analysis of Charm and Beauty Production Cross-section Measurements in Deep Inelastic $ep$ Scattering at HERA

Measurements of open charm and beauty production cross sections in ep deep inelastic scattering (DIS) at HERA from the H1 and ZEUS collaborations are combined. Reduced cross sections are obtained in a restricted kinematic range. Perturbative QCD calculations are compared to the combined data. Next-to-leading order QCD analysis is performed using these data together with combined inclusive HERA DIS cross sections.

Combination and QCD analysis of charm and beauty production cross-section measurements in deep inelastic ep scattering at HERA

Measurements of open charm and beauty production cross sections in deep inelastic ep scattering at HERA from the H1 and ZEUS Collaborations are combined. Reduced cross sections are obtained in the kinematic range of negative four-momentum transfer squared of the photon 2.5~hbox {GeV}^2le Q^2 le 2000, hbox {GeV}^2 and Bjorken scaling variable 3 cdot 10^{-5} le x_mathrm{Bj} le 5 cdot 10^{-2}. The combination method accounts for the correlations of the statistical and systematic uncertainties among the different datasets. Perturbative QCD calculations are compared to the combined data. A next-to-leading order QCD analysis is performed using these data together with the combined inclusive deep inelastic scattering cross sections from HERA. The running charm- and beauty-quark masses are determined as m_c(m_c) = 1.290^{+0.046}_{-0.041} mathrm{(exp/fit)}{}^{+0.062}_{-0.014} mathrm{(model)}{}^{+0.003}_{-0.031} mathrm{(parameterisation)} GeV and m_b(m_b) = 4.049^{+0.104}_{-0.109} mathrm{(exp/fit)}{}^{+0.090}_{-0.032} mathrm{(model)}{}^{+0.001}_{-0.031} mathrm{(parameterisation)}~mathrm{GeV}.

The ratio R = dσL/dσT in heavy-quark pair leptoproduction as a probe of linearly polarized gluons in unpolarized proton

We study the Callan–Gross ratio R=dσL/dσT in heavy-quark pair leptoproduction, lN→l′QQ¯X, as a probe of linearly polarized gluons inside unpolarized proton, where dσT (dσL) is the differential cross section of the γ⁎N→QQ¯X process initiated by a transverse (longitudinal) virtual photon. Note first that the maximal value for the quantity R allowed by the photon-gluon fusion with unpolarized gluons is large, about 2. We calculate the contribution of the transverse-momentum dependent gluonic counterpart of the Boer–Mulders function, h1⊥g, describing the linear polarization of gluons inside unpolarized proton. Our analysis shows that the maximum value of the ratio R depends strongly on the gluon polarization; it varies from 0 to Q24m2 depending on h1⊥g. We conclude that the Callan–Gross ratio in heavy-quark pair leptoproduction is predicted to be large and very sensitive to the contribution of linearly polarized gluons. For this reason, future measurements of the longitudinal and transverse components of the charm and bottom production cross sections at the proposed EIC and LHeC colliders seem to be very promising for determination of the linear polarization of gluons inside unpolarized proton.

Mapping the dominant regions of the phase space associated with cc¯ production relevant for the prompt atmospheric neutrino flux

We present a detailed mapping of the dominant kinematical domains contributing to the prompt atmospheric neutrino flux at high neutrino energies by studying its sensitivity to the cuts on several kinematical variables crucial for charm production in cosmic ray scattering in the atmosphere. This includes the maximal center-of-mass energy for proton-proton scattering, the longitudinal momentum fractions of partons in the projectile (cosmic ray) and target (nucleus of the atmosphere), the Feynman $x_F$ variable and the transverse momentum of charm quark/antiquark. We find that the production of neutrinos with energies larger than $E_{\nu} >$ 10$^7$ GeV is particularly sensitive to the center-of-mass energies larger than the ones at the LHC and to the longitudinal momentum fractions in the projectile 10$^{-8}$ $< x <$ 10$^{-5}$. Clearly, these are regions where we do not control the parton, in particular gluon, densities. We also analyse the characteristic theoretical uncertainties in the charm production cross section coming from its QCD modelling. The precision data on the prompt atmospheric neutrino flux can efficiently constrain the mechanism of heavy quark production and underlying QCD dynamics in kinematical ranges beyond the reach of the current collider measurements.

Measurements of prompt charm production cross-sections in pp collisions at sqrt{s}=5 TeV

Production cross-sections of prompt charm mesons are measured using data from pp collisions at the LHC at a centre-of-mass energy of 5 TeV. The data sample corresponds to an integrated luminosity of 8.60 ± 0.33 pb−1 collected by the LHCb experiment. The production cross-sections of D0, D+, Ds+, and D∗+ mesons are measured in bins of charm meson transverse momentum, pT, and rapidity, y. They cover the rapidity range 2.0 < y < 4.5 and transverse momentum ranges 0 < pT< 10 GeV/c for D0 and D+ and 1 < pT< 10 GeV/c for Ds+ and D∗+ mesons. The inclusive cross-sections for the four mesons, including charge-conjugate states, within the range of 1 < pT< 8 GeV/c are determined to beσpp→D0X=1004±3±54μb,σpp→D+X=402±2±30μb,σpp→Ds+X=170±4±16μb,σpp→D∗+X=421±5±36μb,\\documentclass[12pt]{minimal}\t\t\t\t\\usepackage{amsmath}\t\t\t\t\\usepackage{wasysym}\t\t\t\t\\usepackage{amsfonts}\t\t\t\t\\usepackage{amssymb}\t\t\t\t\\usepackage{amsbsy}\t\t\t\t\\usepackage{mathrsfs}\t\t\t\t\\usepackage{upgreek}\t\t\t\t\\setlength{\\oddsidemargin}{-69pt}\t\t\t\t\\begin{document}$$ \\begin{array}{l}\\sigma \\left( pp\\to {D}^0X\\right)=1004\\pm 3\\pm 54\\mu \\mathrm{b},\\\\ {}\\sigma \\left( pp\\to {D}^{+}X\\right)=402\\pm 2\\pm 30\\mu \\mathrm{b},\\\\ {}\\sigma \\left( pp\\to {D}_s^{+}X\\right)=170\\pm 4\\pm 16\\mu \\mathrm{b},\\\\ {}\\sigma \\left( pp\\to {D}^{\\ast +}X\\right)=421\\pm 5\\pm 36\\mu \\mathrm{b},\\end{array} $$\\end{document}where the uncertainties are statistical and systematic, respectively.

Charmed particles production in pA -interactions at $\surd s = 11.8$ √ s = 11 . 8 GeV

The results of the SERP-E-184 experiment at the U-70 accelerator (IHEP, Protvino) are presented. Interactions of the 70GeV proton beam with carbon, silicon and lead targets were studied to detect decays of charmed \(D^{0}\), \(\bar{D}^{0}\), \(D^{+}\), \(D^{-}\) mesons and \(\Lambda_{c}^{+}\) baryon near their production threshold. Measurements of lifetimes and masses have shown a good agreement with PDG data. The inclusive cross-sections of charm production and their A-dependences have been obtained. The yields of these particles are compared with the theoretical predictions and the data of other experiments. The measured cross-section of the total open charm production ( \(\sigma_{\rm tot}(c\bar{c}) = 7.1 \pm 2.3({\rm stat}) \pm 1.4({\rm syst})\) μb/nucleon) at the collision c.m. energy \(\surd s = 11.8\) GeV is well above the QCD model predictions. The contributions of different kinds of charmed particles to the total cross-section of the open charm production in proton-nucleus interactions vary with energy.

Heavy-flavour production in pp collisions and correlations in pp and p-Pb collisions measured with ALICE at the LHC

Thanks to its excellent tracking and particle identification performance, the ALICE detector is capable of measuring D mesons at mid-rapidity via their hadronic decay channels down to very low transverse momentum. We show an extension of the prompt D0 pT-differential cross section measurement down to zero transverse momentum, which allows us to determine the pT-integrated charm production cross section at mid-rapidity in pp collisions at . We also present measurements of azimuthal correlations of prompt D0, D+ and D*+ mesons with charged hadrons in pp collisions at and p-Pb collisions at and compare the results with expectations from models.

Prompt atmospheric neutrino fluxes: perturbative QCD models and nuclear effects

We evaluate the prompt atmospheric neutrino flux at high energies using three different frameworks for calculating the heavy quark production cross section in QCD: NLO perturbative QCD, $k_T$ factorization including low-$x$ resummation, and the dipole model including parton saturation. We use QCD parameters, the value for the charm quark mass and the range for the factorization and renormalization scales that provide the best description of the total charm cross section measured at fixed target experiments, at RHIC and at LHC. Using these parameters we calculate differential cross sections for charm and bottom production and compare with the latest data on forward charm meson production from LHCb at $7$ TeV and at $13$ TeV, finding good agreement with the data. In addition, we investigate the role of nuclear shadowing by including nuclear parton distribution functions (PDF) for the target air nucleus using two different nuclear PDF schemes. Depending on the scheme used, we find the reduction of the flux due to nuclear effects varies from $10\%$ to $50 \%$ at the highest energies. Finally, we compare our results with the IceCube limit on the prompt neutrino flux, which is already providing valuable information about some of the QCD models.

Erratum to: Measurements of prompt charm production cross-sections in pp collisions at s = 13 $$ \sqrt{s}=13 $$ TeV

C. Baesso, M. Cruz Torres, C. Gobel, J. Molina Rodriguez are associated to Universidade Federal do Rio de Janeiro (UFRJ), Rio de Janeiro, Brazil Y. Xie, J. Yu are associated to Center for High Energy Physics, Tsinghua University, Beijing, China D. A. Milanes, I. A. Monroy, J. A. Rodriguez Lopez are associated to LPNHE, Universite Pierre et Marie Curie, Universite Paris Diderot, CNRS/IN2P3, Paris, France O. Grunberg, M. Hes, C. Vos, R. Waldi are associated to Physikalisches Institut, Ruprecht-Karls-Universitat Heidelberg, Heidelberg, Germany T. Likhomanenko, A. Malinin, V. Shevchenko, A. Ustyuzhanin are associated to Institute of Theoretical and Experimental Physics (ITEP), Moscow, Russia D. Derkach, E. Khairullin, T. Likhomanenko, A. Ustyuzhanin are associated to Institute of Theoretical and Experimental Physics (ITEP), Moscow, Russia F. Martinez Vidal, A. Oyanguren, P. Ruiz Valls, C. Sanchez Mayordomo are associated to Universitat de Barcelona, Barcelona, Spain C. J. G. Onderwater is associated to Nikhef National Institute for Subatomic Physics, Amsterdam, The Netherlands Deceased (T. M. Karbach)

Measurement of D⁎±, D± and [formula omitted] meson production cross sections in pp collisions at [formula omitted] with the ATLAS detector

The production of D⁎±, D± and Ds± charmed mesons has been measured with the ATLAS detector in pp collisions at s=7 TeV at the LHC, using data corresponding to an integrated luminosity of 280 nb−1. The charmed mesons have been reconstructed in the range of transverse momentum 3.5<pT(D)<100 GeV and pseudorapidity |η(D)|<2.1. The differential cross sections as a function of transverse momentum and pseudorapidity were measured for D⁎± and D± production. The next-to-leading-order QCD predictions are consistent with the data in the visible kinematic region within the large theoretical uncertainties. Using the visible D cross sections and an extrapolation to the full kinematic phase space, the strangeness-suppression factor in charm fragmentation, the fraction of charged non-strange D mesons produced in a vector state, and the total cross section of charm production at s=7 TeV were derived.

Measurements of prompt charm production cross-sections in pp collisions at s = 13 $$ \sqrt{s}=13 $$ TeV

Production cross-sections of prompt charm mesons are measured with the first data from $pp$ collisions at the LHC at a centre-of-mass energy of $13\,\mathrm{TeV}$. The data sample corresponds to an integrated luminosity of $4.98 \pm 0.19\,\mathrm{pb}^{-1}$ collected by the LHCb experiment. The production cross-sections of $D^{0}$, $D^{+}$, $D_{s}^{+}$, and $D^{*+}$ mesons are measured in bins of charm meson transverse momentum, $p_{\mathrm{T}}$, and rapidity, $y$, and cover the range $0 < p_{\mathrm{T}} < 15\,\mathrm{GeV}/c$ and $2.0 < y < 4.5$. The ratios of the integrated cross-sections between charm mesons agree with previously measured fragmentation fractions. The inclusive $c\overline{c}$ cross-section within the range of $0 < p_{\mathrm{T}} < 8\,\mathrm{GeV}/c$ is found to be \[ \sigma(pp \to c\overline{c}X) = 2940 \pm 3 \pm 180 \pm 160\,\mu\mathrm{b} \] where the uncertainties are due to statistical, systematic and fragmentation fraction uncertainties, respectively.

Charmed particles production in pA-interactions at 70 GeV

The results of the SERP-E-184 experiment at the U-70 accelerator (IHEP, Protvino) are presented. Interactions of the 70 GeV proton beam with carbon, silicon and lead targets were studied to detect decays of charmed $D^0$, $\bar D^0$, $D^+$, $D^-$ mesons and $\Lambda_c^+$ baryon near their production threshold. Measurements of lifetimes and masses have shown a good agreement with PDG data. The inclusive cross sections of charm production and their A-dependencies have been obtained. The yields of these particles are compared with the theoretical predictions and the data of other experiments. The measured cross section of the total open charm production $\sigma(c\bar c) = 7.1 \pm 2.3(stat) \pm 1.4(syst)$ $\mu$b/nucleon at the collision c.m. energy $\surd s$ = 11.8 GeV is well above the QCD model predictions. The contributions of different kinds of charmed particles to the total cross section of the open charm production in proton-nucleus interactions vary with energy.