Charm Production Cross Section Research Articles

Energy dependence of charm production cross section at high energies

Charm production cross-sections estimated from data obtained in the “Pamir” and other cosmic ray experiments are compared with accelerator data. The strong increase of the charm production cross-section with energy, essential for the explanation of cosmic ray data, is analyzed from a theoretical point of view.

γγ Production of heavy flavour at LEP

The measurements of the experiments ALEPH, DELPHI, L3 and OPAL on heavy quark production in two-photon collisions are presented. The total and differential cross sections for inclusive charm production have been measured at LEP 2 energies. The gluon content of the photon is important to describe the data. The total cross section of inclusive bottom production is three times larger than the QCD prediction.

Feasibility study for the detection of D0 → K−π+ decays in Pb–Pb collisions at LHC with ALICE

The ALICE experiment at the CERN LHC collider is devoted to the study of heavy-ion collisions at a centre of mass energy of 5.5 TeV per nucleon. The study of open charm production in nucleus–nucleus collisions at the LHC allows investigation of the mechanisms of heavy quark production and energy loss in the hot and dense medium formed in the early stage of the collision. In addition, the open charm production cross section is the natural normalization for the study of J/ψ production. The reconstruction of exclusive hadronic decays of charm particles is the only way to obtain a direct measurement of their transverse momentum distribution. We present the results of a feasibility study for the detection of D0 → K−π+ decays in Pb–Pb collisions with ALICE.

Unintegrated gluon in the photon and heavy quark production

The unintegrated gluon density in the photon is determined, using the Kimber-Martin-Ryskin prescription . In addition, a model of the unintegrated gluon is proposed, based on the saturation model extended to the large-x region. These gluon densities are applied to obtain cross sections for charm and bottom production in gamma-p and gamma-gamma collisions using the k_t factorization approach. We investigate both direct and resolved photon contributions and make comparison with the results from the collinear approach and the experimental data. An enhancement of the cross section due to inclusion of non-zero transverse momenta of the gluons is found. The charm production cross section is consistent with the data. The data exceed our conservative estimate for bottom production in gamma-p collisions, but theoretical uncertainties are too large to claim a significant inconsistency. A substantial discrepancy between theory and the experiment is found for gamma gamma -> b bbar X, not being cured by the k_t factorization approach.

A limit on charm produced cosmic ray muon and atmospheric neutrino fluxes

An analysis of cosmic ray muon data at high energies can be used to draw an information on charm production. An empirical model discribing experiment data is proposed. The model is based on the data on behavior of inclusive cross-sections for charm production received in accelerator experiments and ideas on charm production at high energies in the frames of some modern theoretical models based on QCD. Fluxes of neutrinos produced in the atmosphere in decays of charmed particles are calculated. These fluxes can be considered at least as an upper limit on prompt atmospheric neutrino fluxes.

Measurement of the charm structure function F2,cγ of the photon at LEP

The production of charm quarks is studied in deep-inelastic electron–photon scattering using data recorded by the OPAL detector at LEP at nominal e +e − centre-of-mass energies from 183 to 209 GeV. The charm quarks have been identified by full reconstruction of charged D ★ mesons using their decays into D 0 π with the D 0 observed in two decay modes with charged particle final states, K π and K πππ. The cross-section σ D ★ for production of charged D ★ in the reaction e +e −→e +e −D ★ X is measured in a restricted kinematical region using two bins in Bjorken x, 0.0014< x<0.1 and 0.1< x<0.87. From σ D ★ the charm production cross-section σ( e + e −→ e + e − c c ̄ X) and the charm structure function of the photon F 2,c γ are determined in the region 0.0014< x<0.87 and 5< Q 2<100 GeV 2 . For x>0.1 the perturbative QCD calculation at next-to-leading order agrees perfectly with the measured cross-section. For x<0.1 the measured cross-section is 43.8±14.3±6.3±2.8 pb with a next-to-leading order prediction of 17.0 +2.9 −2.3 pb.

Observation of neutral current charm production inνμFescattering at the Fermilab Tevatron

We report on the first observation of open charm production in neutral current deep inelastic neutrino scattering as seen in the NuTeV detector at Fermilab. The production rate is shown to be consistent with a pure gluon-Z0 boson production model, and the observed level of charm production is used to determine the effective charm mass. As part of our analysis, we also obtain a new measurement for the proton-nucleon charm production cross section at s=38.8 GeV. Received 28 August 2000DOI:https://doi.org/10.1103/PhysRevD.64.012002©2001 American Physical Society

Experimental estimation of the charm-production cross section in pp interactions at 70 GeV/c with the aid of the SVD setup

Charmed-particle production in pp interactions at 70 GeV/c was studied with the SVD setup at the IHEP accelerator (Protvino). The experimental procedure used and the data-selection methods are described. Data obtained by using a quickly cycling bubble chamber and a magnetic spectrometer are analyzed. The number of inelastic-interaction events recorded in the chamber is 109000, with the charge multiplicity being nch/4. The corresponding statistics are 4.96 event/µb. Part of the events were recorded in the magnetic spectrometer. Three three-prong decays of charged particles near the primary vertex are found on the films, two of these being recorded with the spectrometer. All three are interpreted as D− decays. Two neutral decays observed simultaneously in the chamber and in the spectrometer are interpreted as \(\bar D^0 \) decays. The total cross section for \(c\bar c\) production in the Feynman variable region −1<xF<+1 is estimated at \(\sigma (c\bar c) = 1.6_{ - 0.7}^{ + 1.1} (stat.) \pm 0.3(syst.)\mu b\). The cross-section values and the mean values 〈|xF|〉 and 〈p⊥〉 for D mesons are compared with other experimental results in the energy range 58–800 GeV. The data of this experiment are compatible with the cross-section estimates obtained in the beam-dump experiment at 70 GeV and with those predicted by perturbative QCD.

Measurements of the cross sections for open charm and beauty production in γγ collisions at [formula omitted]–202 GeV

The production of c and b quarks γγ collisions is studied with the L3 detector at LEP with 410 pb −1 of data, collected at centre-of-mass energies from 189 GeV to 202 GeV. Hadronic final states containing c and b quarks are identified by detecting electrons or muons from their semileptonic decays. The cross sections σ( e + e −→ e + e − c c ̄ X) and σ( e + e −→ e + e − b b ̄ X) are measured and compared to next-to-leading order perturbative QCD calculations. The cross section of b production is measured in γγ collisions for the first time. It is in excess of the QCD prediction by a factor of three.

Measurement of the charm production cross section in γγ collisions at LEP

Open charm production in gamma-gamma collisions is studied with data collected at e+e- centre-of-mass energies from 189 GeV to 202 GeV corresponding to a total integrated luminosity of 410 pb-1. The charm cross section sigma(gamma gamma ---> c c~ X) is measured for the first time as a function of the two-photon centre-of-mass energy in the interval from 5 GeV to 70 GeV and is compared to NLO QCD calculations.

Measurement of the gluon parton distribution function at smallxwith neutrino telescopes

We analyze the possibility that neutrino telescopes may provide an experimental determination of the slope lambda of the gluon distribution in the proton at momentum fractions x smaller than the accelerator reach. The method is based on a linear relation between lambda and the spectral index (slope) of the down-going atmospheric muon flux above 100 TeV, for which there is no background. Considering the uncertainties in the charm production cross section and in the cosmic ray composition, we estimate the error on the measurement of lambda through this method, excluding the experimental error of the telescopes, to be ~ +/- 0.2

Bottom and charm production at LHC and RHIC

We study b b ̄ and c c ̄ production and the influence of nuclear shadowing at LHC and RHIC energies. We find a significant reduction in the production cross section of both charm and bottom at RHIC and LHC. Bound states such as ϒ and J/ Ψ are suppressed by this reduction in the charm production cross sections. Therefore, J/ Ψ suppression may not be useful as a signature for the quark gluon plasma.

Dimuon and charm production in nucleus-nucleus collisions at the CERN-SPS

Muon pair production in p-A, S-U and Pb-Pb collisions has been studied by the NA38 and NA50 collaborations at the CERN SPS. In this paper we present an analysis of the dimuon invariant mass region between the $\phi$ and the J/ $\psi$ . In p-A collisions we find that, after the subtraction of the combinatorial background due to $\pi$ and K decays, the superposition of dimuons from semi-leptonic decays of D mesons and from the Drell-Yan process reproduces well the measured mass and transverse momentum spectra. The yield of open charm dimuons required to fit our data leads to a charm production cross section in good agreement with previous measurements. A linear extrapolation of the p-A sources with the product of the mass numbers of the projectile and target nuclei, $A\times B$ , underestimates the dimuon yield measured in S-U and Pb-Pb collisions. The excess increases with the number of participant nucleons, and the ratio between the observed dimuon yield and the expected sources reaches a factor 2 for central Pb-Pb interactions. The kinematical distributions of the measured dimuon excess are compatible with those expected from the open charm contribution.

Inclusive charm production in two-photon collisions at LEP

The cross section of charm production in γγ collisions σ(e +e −→e +e −c c ̄ X) is measured at LEP with the L3 detector at centre-of-mass energies from 91 GeV to 183 GeV. Charmed hadrons are identified by electrons and muons from semileptonic decays. The direct process γγ→c c ̄ is found to be insufficient to describe the data. The measured cross section values and event distributions require contributions from resolved processes, which are sensitive to the gluon density in the photon.

Total charm production cross section and production asymmetries in 340 GeV/ c Σ −-nucleus interactions

CERN experiment WA89 uses a Σ − beam at 340 GeV/c to study the production of charmed particles. Based on the reconstruction of all final charm states from the full data sample of our '93 and '94 beamtimes the total cc-cross section has been determined. Production of particles which have a light quark in common with the beam is compared to production of those which do not. Considerable production asymmetries between D − and D + , D - s and D + s , and Λ c and ¯Ac are observed.

Charm and beauty production in high energy cosmic ray interaction with air nuclei

We calculate the A-dependences of open charm and beauty production cross sections on air nuclear targets taking into account the difference of quark and gluon distributions in free and bound nucleons. The results are presented for the cases of nucleon, 14 N and iron beams. For the case of heavy flavour production at high energies, if σ ~ A α , the values of α are smaller than unity.

Secondary decays in atmospheric charm contributions to the flux of muons and muon neutrinos

We present a calculation of the fluxes of muons and muon neutrinos from the decays of pions and kaons that are themselves the decay products of charmed particles produced in the atmosphere by cosmic ray-air collisions. Using the perturbative cross section for charm production, these lepton fluxes are two to three orders of magnitude smaller than the fluxes from the decays of pions and kaons directly produced in cosmic ray-air collisions. Intrinsic charm models do not significantly alter our conclusions for E < 10 3 GeV. Models with a charm cross section enhanced in the region above an incident cosmic ray energy of 10 3 GeV give enhanced lepton fluxes above 10 4 GeV, a region in which prompt muons dominate over the secondary decay contributions.

Charm and bottom quark production cross sections near threshold

The cross sections for charm and bottom quark production in the threshold region are discussed. We consider the effects of an all order resummation of initial state soft-plus-virtual gluon radiation on the total cross sections compared to the order $\alpha_s^3$ results.

Cross section for charm production in proton-nucleon collisions at 70 GeV according to the results of a beam-dump experiment with the IHEP-JINR neutrino detector

Cross section for charm production in proton-nucleon collisions at 70 GeV according to the results of a beam-dump experiment with the IHEP-JINR neutrino detector

Open charm production at HERA

Measurements of charm production cross sections in electron-proton collisions at low Q2 are reviewed for various kinematic regimes. The dependence of the differential cross section on the D* transverse momentum and rapidity is presented and compared to next to leading order QCD calculations. First results on inclusive D0 and D*+ production in deep inelastic ep scattering are reported for data collected by the H1 and ZEUS experiments at HERA in 1994. The first measurement of the charm contribution Fcc̄2 to the proton structure function for 6 × 10−4 < xBj < 7.5 × 10−3 is discussed. First evidence for diffractive production of D*+ mesons both in photoproduction and in deep-inelastic interactions at HERA is presented.