14 research outputs found
Exclusive double-diffractive production of open charm in proton-proton and proton-antiproton collisions
We calculate differential cross sections for exclusive double diffractive
(EDD) production of open charm in proton-proton and proton-antiproton
collisions. Sizeable cross sections are found. The EDD contribution constitutes
about 1 % of the total inclusive cross section for open charm production. A few
differential distributions are shown and discussed. The EDD contribution falls
faster both with transverse momentum of the quark/antiquark and the invariant mass than in the inclusive case.Comment: 11 pages, 7 figure
Elastic double diffractive production of axial-vector \chi_c(1^{++}) mesons and the Landau-Yang theorem
We discuss exclusive elastic double diffractive axial-vector \chi_c(1^{+})
meson production in proton-antiproton collisions at the Tevatron. The amplitude
for the process is derived within the k_t-factorisation approach with
unintegrated gluon distribution functions (UGDFs). We show that the famous
Landau-Yang theorem is not applicable in the case of off-shell gluons.
Differential cross sections for different UGDFs are calculated. We compare
exclusive production of \chi_c(1^+) and \chi_c(0^+). The contribution of
\chi_c(1^+) to the J/\Psi + \gamma channel is smaller than that of the
\chi_c(0^+) decay, but not negligible and can be measured. The numerical value
of the ratio of the both contributions is almost independent of UGDFs modeling.Comment: 14 pages, 5 figures, a numerical error corrected, discussions
extended, conclusions unchange
Diagonalization of the neutralino mass matrix and boson-neutralino interaction
We analyze a connection between neutralino mass sign, parity and structure of
the neutralino-boson interaction. Correct calculation of spin-dependent and
spin-independent contributions to neutralino-nuclear scattering should consider
this connection. A convenient diagonalization procedure, based on the
exponetial parametrization of unitary matrix, is suggested.Comment: 21 pages, RevTex
Fine structure of anomalous dimensions in N=4 super Yang-Mills theory
Anomalous dimensions of high-twist Wilson operators in generic gauge theories
occupy a band of width growing logarithmically with their conformal spin. We
perform a systematic study of its fine structure in the autonomous SL(2)
subsector of the dilatation operator of planar N=4 super Yang-Mills theory
which is believed to be integrable to all orders in 't Hooft coupling. We
resort in our study on the framework of the Baxter equation to unravel the
properties of the ground state trajectory and the excited trajectories in the
spectrum. We use two complimentary approaches in our analysis based on the
asymptotic solution of the Baxter equation and on the semiclassical expansion
to work out the leading asymptotic expression for the trajectories in the upper
and lower part of the band and to find how they are modified by the
perturbative corrections.Comment: 34 pages; v2: minor corrections, reference adde