337 research outputs found
Systematics of heavy quarkonia from Regge trajectories on and planes
In this paper we show that heavy quarckonium states, similar to light mesons,
form Regge trajectories in and 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
Associative production of B_c and D mesons at LHC
It is shown that the study of correlations in the associative production of
B_c and D mesons at LHC allows to obtain the essential information about the
B_c production mechanism.Comment: 14 pages, 10 figures. Some misprints have been removed in the last
version. The reference to CTEQ pdf has been adde
Central exclusive production of scalar \chi_c meson at the Tevatron, RHIC and LHC energies
We calculate several differential distributions for exclusive double
diffractive production in proton-antiproton collisions at the
Tevatron and in proton-proton collisions at RHIC and LHC in terms of
unintegrated gluon distributions (UGDFs) within the -factorisation
approach. The uncertainties of the Khoze-Martin-Ryskin approach are discussed
in detail. The transition vertex is calculated as
a function of gluon virtualities applying the standard pNRQCD technique. The
off-shell effects are discussed and quantified. They lead to a reduction of the
cross section by a factor 2--5, depending on the position in the phase space
and UGDFs. Different models of UGDFs are used and the results are shown and
discussed. The cross section for diffractive component depends strongly on
UGDFs. We calculate also the differential distributions for the fusion mechanism. The integrated cross section for
photon-photon fusion is much smaller than that of diffractive origin. The two
components have very different dependence on momentum transfers in
the nucleon lines as well as azimuthal-angle correlations between both outgoing
nucleons.Comment: 34 pages, 23 figures, 2 table
An Exact Approach to the Oscillator Radiation Process in an Arbitrarily Large Cavity
Starting from a solution of the problem of a mechanical oscillator coupled to
a scalar field inside a reflecting sphere of radius , we study the behaviour
of the system in free space as the limit of an arbitrarily large radius in the
confined solution. From a mathematical point of view we show that this way of
facing the problem is not equivalent to consider the system {\it a} {\it
priori} embedded in infinite space. In particular, the matrix elements of the
transformation turning the system to principal axis, do not tend to
distributions in the limit of an arbitrarily large sphere as it should be the
case if the two procedures were mathematically equivalent. Also, we introduce
"dressed" coordinates which allow an exact description of the oscillator
radiation process for any value of the coupling, strong or weak. In the case of
weak coupling, we recover from our exact expressions the well known decay
formulas from perturbation theory.Comment: 27 page
Diffractive charm photoproduction at HERA ep-collider
The cross section of the -meson diffractive photoproduction at the HERA
collider has been calculated in the framework of perturbatively motivated model
for the different kinematic regions. The camparison between the different
Pomeron models has been performed.Comment: 9 pages, 3 figure
Scanning the Quark-Gluon Plasma with Charmonium
We suggest the variation of charmonium suppression with Feynman x_F in heavy
ion collisions as a novel and sensitive probe for the properties of the matter
created in such reactions. In contrast to the proton-nucleus case where nuclear
suppression is weakest at small x_F, final state interactions with the comoving
matter create a minimum at x_F=0, which is especially deep and narrow if a
quark-gluon plasma is formed. While a particularly strong effect is predicted
at SPS, at the higher RHIC energy it overlaps with the expected sharp variation
with x_F of nuclear effects and needs comparison with proton-nucleus data. If
thermal enhancement of J/\Psi production takes over at the energies of RHIC and
LHC, it will form an easily identified peak, rather than dip in x_F dependence.
We predict a steep dependence on centrality and suggest that this new probe is
complementary to the dependence on transverse energy, and is more sensitive to
a scenario of final state interactions.Comment: 5 pages including 3 figures. Stylistic and clarifying corrections are
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