3,203 research outputs found

### Observation potential for \chi_b at the Tevatron and LHC

We confirm the results of previous works that the internal motion of quarks
inside charmonium mesons increases the cross section of the process $e^+e^-\to$J/\psi\eta_c$. We also show, that this effect increases the widths of the
scalar meson decay into two vector ones and state that the decays$\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 $(n,M^2)$ and $(M^2,J)$ planes

In this paper we show that heavy quarckonium states, similar to light mesons,
form Regge trajectories in $(n,M^2)$ and $(M^2,J)$ 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

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 $B_{c}$ meson in a semi-relativistic quark model using the shifted large-N expansion method

We calculate the $c\bar{b}$ 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 $c\bar{b}$ 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

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

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

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

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