63 research outputs found
Mass spectra and leptonic decay widths of heavy quarkonia
A nonrelativistic Hamiltonian with plausible spin dependent corrections is
proposed for the quarkonia below their respective strong decay thresholds. With
only six free parameters this model reproduces the nine known masses of the
bottomonia within about 1 MeV, the six known masses of the charmonia within a
few MeV and the five known leptonic decay widths of the states within
about {20 %}. The model is then used to predict the masses of the remaining 43
quarkonia (some of them for the first time) and of the leptonic decay widths of
the two states. Comparison with some other models is made.Comment: Latex file, 19 pages; Zs. f. Ph. C in prin
Twist decomposition of proton structure from BFKL and BK amplitudes
An analysis of twist composition of Balitsky-Kovchegov (BK) amplitude is
performed in the double logarithmic limit. In this limit the BK evolution of
color dipole -- proton scattering is equivalent to BFKL evolution which follows
from vanishing of the Bartels vertex in the collinear limit. We perform twist
decomposition of the BFKL/BK amplitude for proton structure functions and find
compact analytic expressions that provide accurate approximations for higher
twist amplitudes. The BFKL/BK higher twist amplitudes are much smaller than
those following from eikonal saturation models.Comment: 10 pages, 5 figure
On relevance of triple gluon fusion in hadroproduction
A contribution to hadroproduction is analyzed in which the meson
production is mediated by three-gluon partonic state, with two gluons coming
from the target and one gluon from the projectile. This mechanism involves
double gluon density in one of the protons, hence this contribution enters at a
non-leading twist. It is, however, relevant due to an enhancement factor coming
from large double gluon density at small~. We calculate the three-gluon
contribution to hadroproduction within perturbative QCD in the
-factorization framework. Results are obtained for differential
-dependent cross-sections for all polarizations and for the sum
over the polarization components. The rescattering contribution is found to
provide a significant correction to the standard leading twist cross-section at
the energies of the Tevatron or the LHC at moderate . We suggest
production in proton-nucleus collision as a possible probe of the triple gluon
mechanism.Comment: 20 pp, 9 figure
On multiple gluon exchange in J/psi hadroproduction
We consider a contribution to J/psi hadroproduction in which the meson
production is mediated by three-gluon partonic state, with two gluons coming
from the target and one gluon from the projectile. This mechanism involves
double gluon density and thus it enters at a non-leading twist, but it is
enhanced at large energies due to large double gluon density at small x. The
three-gluon contribution to J/psi hadroproduction is calculated within
perturbative QCD in the k_T factorization framework, and it is found to provide
a significant correction to the standard leading twist cross-section at the
energies of the Tevatron or the LHC. The results are given as differential
p_T-dependent cross-sections for J/psi polarization components.Comment: 6 pages, 2 figures, talk given at XXII. International Workshop on
Deep-Inelastic Scattering and Related Subjects, 28 April - 2 May 2014,
Warsaw, Polan
Diffractive heavy vector meson production from the BFKL equation
Diffractive heavy vector meson photoproduction accompanied by proton
dissociation is studied for arbitrary momentum transfer. The process is
described by the non-forward BFKL equation, for which a complete analytical
solution is found, giving the scattering amplitude. The impact of non-leading
corrections to the BFKL equation is also analysed. Results are compared to the
HERA data on J/psi production.Comment: 20 pages, 8 figures, version to appear in EPJC. Discussion of
infrared details expande
Twist expansion of differential cross-sections of forward Drell-Yan process
Forward Drell-Yan process at the LHC is a sensitive tool for investigating
higher twist effects in QCD. The expansion of all Drell-Yan structure functions
is performed assuming GBW saturation model and the saturation scale plays the
role of the hadronic scale of OPE. We show that the Lam-Tung relation is broken
at twist 4. The results open the way for a forthcoming analysis of multiple
scattering and higher twist effects.Comment: 4 pages, 2 figures, talk presented at the International Workshop on
Diffraction in High-Energy Physics Primosten (Croatia), September 10 - 16,
201
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