Heavy-flavour Production Cross Sections Research Articles

The impact of the LHCb B± production cross-section on parton distribution functions and determining the mass of heavy quarks

In this work, the impact of recent measurements of heavy-flavour production in pp collisions on parton distribution functions (PDFs) and their uncertainties is studied. In this regard, the absolute and normalised cross sections of beauty hadron production measured by LHCb at center-of-mass energy of 7 TeV and 13 TeV are separately included in the next-to-leading order (NLO) global QCD analysis together with the measurements of the inclusive and heavy-flavour production cross sections at HERA. It is illustrated that the heavy-flavour data of the LHCb experiment impose additional constraints on the PDFs, especially on the gluon distribution at low partonic fractions x of the proton momentum. One of the most important results of the present analysis is the significant reduction of the gluon uncertainties in the region less than x=10−4 that can play a crucial rule in many areas of high energy physics investigations.

Impact of heavy-flavour production cross sections measured by the LHCb experiment on parton distribution functions at low x

The impact of recent measurements of heavy-flavour production in deep inelastic $ep$ scattering and in $pp$ collisions on parton distribution functions is studied in a QCD analysis in the fixed-flavour number scheme at next-to-leading order. Differential cross sections of charm- and beauty-hadron production measured by LHCb are used together with inclusive and heavy-flavour production cross sections in deep inelastic scattering at HERA. The heavy-flavour data of the LHCb experiment impose additional constraints on the gluon and the sea-quark distributions at low partonic fractions $x$ of the proton momentum, down to $x \sim 5 \times 10^{-6}$. This kinematic range is currently not covered by other experimental data in perturbative QCD fits.

Open-charm production as a function of charged particle multiplicity in pp collisions at = 7 TeV with ALICE

Heavy quarks (charm and beauty) are an effective tool to investigate the properties of the Quark-Gluon Plasma created in heavy-ion collisions as they are produced in initial hard scattering processes and as they experience all the stages of the medium evolution. The measurement of heavy-flavour production cross sections in pp collisions at the LHC, besides providing a reference for heavy-ion studies, allows one to test perturbative QCD calculations. A brief review of ALICE results on the production of heavy-flavoured hadrons measured from fully reconstructed hadronic decay topologies in pp collisions at = 7 TeV is presented. Furthermore, heavy-flavour production was also studied as a function of the particle multiplicity in pp collisions. This could provide insight into multi-parton scatterings. A measurement of the inclusive J/ψ yield as a function of the charged-particle pseudorapidity density was performed by the ALICE Collaboration at the LHC in pp collisions at = 7 TeV. An increase of the J/ψ yield with increasing multiplicity was observed. In this context, the study of the yield of D mesons as a function of the charged-particle multiplicity could provide a deeper insight into charm-quark production in pp collisions. We will present the first results obtained for prompt D0, D+, and D*+ mesons using hadronic decay channels at midrapidity in pp collisions at = 7 TeV as a function of the charged-particle multiplicity. The prompt D-meson yields as a function of multiplicity are measured in different pT intervals. These yields will be compared to the results obtained for inclusive and non-prompt J/ψ.

Heavy Flavour Cross Section Measurements with the ATLAS Detector

ATLAS measurements of heavy flavour production cross sections are presented from proton-proton collisions at the LHC at a centre-of-mass energy of 7 TeV. These make use of b-hadron decays to D⁎μX, inclusive charm meson production, inclusive electron and muon production from semileptonic heavy flavour decays, and reconstruction of secondary decay vertices to tag b-jets. The results are compared with next-to-leading-order QCD calculations.

Measurement of heavy-flavour production in proton–proton collisions at [formula omitted] with ALICE

The measurement of the heavy-flavour production cross sections in pp collisions at the LHC will allow to test perturbative QCD calculations in a new energy domain. Moreover, within the physics program of the ALICE experiment, it will provide the reference for the study of medium effects in Pb–Pb collisions, where heavy quarks are regarded as sensitive probes of parton–medium interaction dynamics. We present the status and first preliminary results of charm and beauty production measurements with the ALICE experiment, using hadronic D meson decays and semi-leptonic D and B meson decays, including the first cross section measurement of muons from heavy flavour decays at forward rapidity. We also describe the preliminary cross section measurement for J / ψ production, obtained using the di-electron decay channel at central rapidity and the di-muon decay channel at forward rapidity.

Heavy flavour production cross-sections from fixed target to collider energies

We review the hadro-production data presently available on charm and beauty absolute production cross-sections, collected by experiments at CERN, DESY and Fermilab. After correcting the published values, in particular for the ‘time evolution’ of the branching ratios, the measurements are compared to LO pQCD calculations performed with Pythia, as a function of the collision energy, using the latest parametrizations of the parton distribution functions. We then estimate, including nuclear effects on the parton densities, the charm and beauty production cross-sections relevant for future measurements at SPS, RHIC and LHC energies, in proton–proton and nucleus–nucleus collisions. We also compare some indirect charm measurements, done using leptonic decays, to the others and we briefly address the importance of beauty production as a feed-down mechanism of J/ψ production.

Nuclear structure functions and heavy flavour leptoproduction off the nucleus at small x in perturbative QCD

Nuclear structure functions and cross-sections for heavy flavour production in lepton-nucleus collisions are investigated in the low $x$ region accessible now or in the near future. The scattering on a heavy nucleus is described by the sum of fan diagrams of BFKL pomerons, which is exact in the high-colour limit. The initial condition for the evolution at $x=0.01$ is taken from a saturation model, which reproduces the experimental data on the proton. The $A$ dependence of the structure functions is well described by a power factor $A^\alpha$, with $\alpha$ reaching values as low as 1/2 at extremely low $x$. The total cross-sections for heavy flavour production reach values of the order of mb, and the corresponding transverse momentum distributions are sizeable up to transverse momenta larger than the initial large scale $\sqrt{Q^2+4m_f^2}$.

Complete O( αS) corrections to heavy-flavour structure functions in electroproduction

The complete O( α S) QCD corrections to the virtual-photon cross sections for heavy-flavour production in deep-elastic electron-proton scattering are presented. These results are then used to calculate the O( α S) corrections to the heavy-flavour contributions to the structure functions F 2( x, Q 2, m 2) and F L( x, Q 2, m 2). We examine these corrections in the x and Q 2 range appropriate for c- and b-quark production at HERA. Our results are also compared with the O( α S) plus O( α S 2) corrections for massless quarks.