Inclusive D* Production in Photon-Photon Collisions at Next-to-Leading Order QCD

The next-to-leading order cross section for the inclusive production of charm quarks in gamma-gamma collisions is calculated as a function of the transverse momentum pT and the rapidity y in approaches using massive or massless charm quarks. For the direct cross section we derive the massless limit from the massive theory with the result that this limit differs from the massless version with MSbar factorization by finite corrections. Subtracting or adding these corrections allows us to compare the two approaches on equal footing. We establish massless and massive versions with 3 and 4 initial flavours which are shown to approach the massless approximations very fast with increasing pT. With these results we calculate the inclusive D* cross section in gamma-gamma collisions using realistic evolved fragmentation functions with appropriate factorization scales and compare with recent data for dsigma/dpT from three LEP collaborations after single- and double-resolved contributions have been added.Comment: 27 pages, 8 figures, LaTe

LARGE LOGARITHM BEHAVIOUR OF e^+e^- JET CROSS SECTIONS AND EVENT SHAPE DISTRIBUTIONS IN O(alpha_s^2)

We have calculated the leading and next-to-leading logarithm coefficients of $O(\alpha_s^2)$ $e^+e^-$ annihilation jet cross sections, thrust distribution and energy-energy correlation in the two-jet limit when the jet resolution and the event shape variables vanish. We have compared our results with expectations based on leading logarithm approximations used to resum the pertubative cross sections where this is possible. There is good agreement for the leading and next-to-leading coefficients of jet cross sections in the Durham scheme. Also for the thrust distribution and energy-energy correlation we find results which are consistent with the leading logarithm predictions.Comment: 22 pages, uuencoded postscript, no figure

Inclusive D* production in gamma-gamma collisions: including the single-resolved contribution with massive quarks

We have calculated the next-to-leading order cross section for the inclusive production of charm quarks as a function of the transverse momentum p_T and the rapidity in two approaches using massive or massless charm quarks. For the single-resolved cross section we have derived the massless limit from the massive theory. We find that this limit differs from the genuine massless version with MS-bar factorization by finite corrections. By adjusting subtraction terms we establish a massive theory with MS-bar subtraction which approaches the massless theory very fast with increasing transverse momentum. With these results and including the equivalent results for the direct cross section obtained previously as well as double-resolved contributions, we calculate the inclusive D*+- cross section in gamma-gamma collisions using realistic evolved non-perturbative fragmentation functions and compare with recent data from the LEP collaborations ALEPH, L3 and OPAL. We find good agreement.Comment: 34 pages including postscript figure

b-Hadron production in the general-mass variable-flavour-number scheme and LHC data

We study inclusive b-hadron production in pp collisions at the LHC at different center-of-mass energies and compare with experimental data from the LHCb and CMS collaborations. Our predictions for cross sections differential in the transverse momentum and (pseudo-)rapidity agree with data within uncertainties due to renormalization scale variations. A small tension is found if data and theory predictions are compared for cross section ratios at different center-of-mass energies.Comment: 22 pages. Replaced LHCb data: now match with revised version (v9) of arXiv:1612.0514

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Spherical Orbifolds for Cosmic Topology

Harmonic analysis is a tool to infer cosmic topology from the measured astrophysical cosmic microwave background CMB radiation. For overall positive curvature, Platonic spherical manifolds are candidates for this analysis. We combine the specific point symmetry of the Platonic manifolds with their deck transformations. This analysis in topology leads from manifolds to orbifolds. We discuss the deck transformations of the orbifolds and give eigenmodes for the harmonic analysis as linear combinations of Wigner polynomials on the 3-sphere. These provide new tools for detecting cosmic topology from the CMB radiation.Comment: 17 pages, 9 figures. arXiv admin note: substantial text overlap with arXiv:1011.427

Study of heavy meson production in p-Pb collisions at S\sqrt{S}=5.02 TeV in the general-mass variable-flavour-number scheme

We study inclusive charm and bottom production, for both D and B mesons, in p-Pb collisions at the LHC. Numerical results for p_T-differential production cross sections are obtained at next-to-leading-order in the general-mass variable-flavor-number scheme. We compare our results with recent data from ALICE, LHCb and CMS at a center-of-mass energy of 5 TeV and find good agreement. A comparison with p-p cross sections does not reveal the presence of nuclear initial-state interaction effects that could be expected to become visible as deviations of the ratio of p-Pb and p-p cross sections from one.Comment: 20 pages, extended discussion, agrees with published version in Nucl.Phys.