3,203 research outputs found

    Observation potential for \chi_b at the Tevatron and LHC

    Full text link
    We confirm the results of previous works that the internal motion of quarks inside charmonium mesons increases the cross section of the process e+ee^+e^-\to J/\psi\eta_c.Wealsoshow,thatthiseffectincreasesthewidthsofthescalarmesondecayintotwovectoronesandstatethatthedecays. We also show, that this effect increases the widths of the scalar meson decay into two vector ones and state that the decays \chi_{b0,2}\to2J/\psi$ can be used to detect these scalar mesons at Tevatron and LHC colliders.Comment: 13 pages, 5 figures, error in fig.3 correcte

    Systematics of heavy quarkonia from Regge trajectories on (n,M2)(n,M^2) and (M2,J)(M^2,J) planes

    Full text link
    In this paper we show that heavy quarckonium states, similar to light mesons, form Regge trajectories in (n,M2)(n,M^2) and (M2,J)(M^2,J) planes and the slope of these trajectories is independent on the quantum numbers of the mesons. This fact can be useful for the prediction of the masses of heavy quarkonia and the determination of the quantum numbers of the newly discovered states.Comment: 10 pages, 2 figures, 2 tables; some refrences are added, comparison with QCD sum rules result is presente

    Inclusive B-Meson Production at the LHC in the GM-VFN Scheme

    Full text link
    We calculate the next-to-leading-order cross section for the inclusive production of B mesons in pp collisions in the general-mass variable-flavor-number scheme, an approach which takes into account the finite mass of the b quarks. We use realistic evolved non-perturbative fragmentation functions obtained from fits to e+e- data and compare results for the transverse-momentum and rapidity distributions at a center-of-mass energy of 7 TeV with recent data from the CMS Collaboration. We find good agreement, in particular at large values of pT.Comment: Minor changes to the text, accepted for publication in Phys. Rev.

    Spectroscopy of BcB_{c} meson in a semi-relativistic quark model using the shifted large-N expansion method

    Full text link
    We calculate the cbˉc\bar{b} mass spectrum, the splitting values and some other properties in the framework of the semi-relativistic equation by applying the shifted large-N expansion technique. We use seven different central potentials together with an improved QCD-motivated interquark potentials calculated to two loops in the modified minimal-subtraction % (\bar{MS}) scheme. The parameters of these potentials are fitted to generate the semi-relativistic bound states of cbˉ c\bar{b} quarkonium system in close conformity with the experimental and the present available calculated center-of-gravity (c.o.g.) data. Calculations of the energy bound states are carried out up to third order. Our results are in excellent fit with the results of the other works.Comment: 3

    Decay eta_b->J/\psi J/\psi in light cone formalism

    Get PDF
    The decays of pseudoscalar bottomonium eta_b into a pair of vector charmonia, J/\psi J/\psi, J/\psi \psi', \psi' \psi' are considered in the light cone formalism. Relativistic and leading logarithmic radiative corrections to the amplitudes of these processes are resummed. It is shown that the small value for the branching ratio of the decay eta_b-> J/\psi J/\psi obtained within the leading order nonrelativistic QCD is a consequence of a fine-tuning between certain parameters, which is broken when relativistic and leading logarithmic radiative corrections are taken into account. As a result, the branching ratio obtained in this paper is enhanced by an order of magnitude.Comment: 7 pages, 1 figur

    Electron bremstrahlung recovery in ATLAS tracking using Dynamic Noise Adjustment

    Get PDF
    A number of approaches are being used in ATLAS reconstruction software, aiming to improve electron momentum measurement by taking into account the effects due to bremsstrahlung at various stages. One of them, designed and implemented in ATLAS, is covered in this talk. The method applies Dynamic Noise Adjustment (DNA) during the track fitting process based on the Kalman filter, and is both fast and efficien

    Centrality, Rapidity and Transverse-Momentum Dependence of Cold Nuclear Matter Effects on J/Psi Production in d+Au, Cu+Cu and Au+Au Collisions at sqrt(s_NN)=200 GeV

    Full text link
    We have carried out a wide study of Cold Nuclear Matter (CNM) effects on J/Psi production in d+Au, Cu+Cu and Au+Au collisions at sqrt(s_NN)=200 GeV. We have studied the effects of three different gluon-shadowing parametrisations, using the usual simplified kinematics for which the momentum of the gluon recoiling against the J/Psi is neglected as well as an exact kinematics for a 2 -> 2 process, namely g+g -> J/psi+g as expected from LO pQCD. We have shown that the rapidity distribution of the nuclear modification factor R_dAu, and particularly its anti-shadowing peak, is systematically shifted toward larger rapidities in the 2 -> 2 kinematics, irrespective of which shadowing parametrisation is used. In turn, we have noted differences in the effective final-state nuclear absorption necessary to fit the PHENIX d+Au data. Taking advantage of our implementation of a 2 -> 2 kinematics, we have also computed the transverse momentum dependence of the latter nuclear modification factor, which cannot be predicted with the usual simplified kinematics. All the corresponding observables have been computed for Cu+Cu and Au+Au collisions and compared to the PHENIX and STAR data. Finally, we have extracted the effective nuclear absorption from the recent measurements of R_CP in d+Au by the PHENIX collaboration.Comment: 12 pages, 14 figures, LaTeX. Version to appear in Phys. Rev. C: a few typos corrected and one comment about the EPS08 nPDF parametrisation adde
    corecore