337 research outputs found
A test of the BFKL resummation at ILC
We consider the exclusive production of rho^0 meson pairs in gamma^*gamma^*
scattering in the Regge limit of QCD as a probe of BFKL resummation effects and
we show the feasibility of the measurement of this process at the ILC.Comment: To appear in the proceedings of the School on QCD, low-x physics,
saturation and diffraction, Copanello Calabria, Italy, July 1-14 200
Production of rho meson pair in gamma* gamma* collisions
We have shown that the lowest order QCD amplitude, i.e. the quark exchange
contribution, to the forward production of a pair of longitudinally polarized
rmesons in the scattering of two virtual photons gamma (Q1) gamma (Q2) rho rho
factorizes in two different ways: the part with transverse photons is described
by the QCD factorization formula involving the generalized distribution
amplitude of two final rho mesons, whereas the part with longitudinally
polarized photons takes the QCD factorized form with the gamma rho transition
distribution amplitude. Perturbative expressions forthese, in general,
non-perturbative functions are obtained in terms of the rho meson distribution
amplitude.Comment: International Workshop on Diffraction in High-Energy Physics
-DIFFRACTION 2006 - September 5-10 2006 Adamantas, Milos island, Greec
Noise and deviation effects in a bichromatic Raman white light cavity
We analyze the effects of noise and parameter deviations in a bichromatic
Raman type white light cavity, with potential applications in precision
measurements such as gravitational wave detection. The results show that the
dispersion variation induced by parameter deviation can be controlled within
. The laser phase noise decreases the dispersion magnitude while the
amplitude noise increases it. Although we can always adjust the parameters to
satisfy the white light condition, both noises make the cavity transmission
curve uneven.Comment: 5 pages, 3 figure
Photoproduction of a \pi \rho Pair and Transversity GPDs
We demonstrate that the chiral-odd transversity generalized parton
distributions (GPDs) of the nucleon can be accessed through the exclusive
photoproduction process gamma + N -> pi + rho + N', in the kinematics where the
meson pair has a large invariant mass and the final nucleon has a small
transverse momentum, provided the vector meson is produced in a transversely
polarized state. We calculate perturbatively the scattering amplitude at
leading order in alpha_s: We build a simple model for the dominant transversity
GPD HT (x; chi; t) based on the concept of double distribution. Counting rates
estimates show that the experiment looks feasible with the real photon beam
characteristics expected at JLab@12 GeV, in low Q2 leptoproduction at Jlab@12
GeV and in the COMPASS experiment.Comment: Latex, 7 pages, 4 .eps figs, Invited talk at the 4th Workshop on
Exclusive Reactions at High Momentum Transfer May 18-21, 2010 Thomas
Jefferson National Accelerator Facility, Newport News, Virginia US
Chiral-odd transversity GPDs from a leading twist hard amplitude
The chiral-odd transversity generalized parton distributions (GPDs) of the
nucleon can be accessed experimentally through the exclusive photoproduction
process gamma + N -> pi + rho + N', in the kinematics where the meson pair has
a large invariant mass and the final nucleon has a small transverse momentum,
provided the vector meson is produced in a transversally polarized state. We
calculate perturbatively the scattering amplitude at leading order in alpha_s.
We build a simple model for the dominant transversity GPD H_T(x,xi,t) based on
the concept of double distribution. We estimate the unpolarized differential
cross section for this process in the kinematics of the Jlab and COMPASS
experiments. Counting rates show that the experiment looks feasible with the
real photon beam characteristics expected at JLab@12 GeV, and with the quasi
real photon beam in the COMPASS experiment.Comment: 5 pages, to appear in the proceedings of 18th International Workshop
on Deep-Inelastic Scattering and Related Subjects (DIS 2010), Florence,
Italy, 19-23 Apr 201
On chiral-odd Generalized Parton Distributions
While the chiral-even content of the nucleon is better and better studied,
the chiral-odd transversity generalized parton distributions (GPDs) remain
almost unknown. These GPDs can be accessed experimentally through the exclusive
photoproduction process gamma + N -> pi + rho + N', in the kinematics where the
meson pair has a large invariant mass and the final nucleon has a small
transverse momentum, provided the vector meson is produced in a transversally
polarized state. We calculate perturbatively the scattering amplitude at
leading order in alpha_s. We build a simple model for the dominant transversity
GPD H_T(x,xi,t) based on the concept of double distribution. We estimate the
unpolarized differential cross section for this process in the kinematics of
the Jlab and COMPASS experiments. Counting rates show that the experiment looks
feasible with the real and quasi real photon beam characteristics expected at
JLab@12 GeV, and with the quasi real photon beam in the COMPASS experiment.Comment: 5 pages, to appear in the proceedings of 35th International
Conference on High Energy Physics, (ICHEP 2010), Paris, France, July 22-28,
201
Towards the theory of coherent hard dijet production on hadrons and nuclei
We carry out a detailed calculation of the cross section of pion diffraction
dissociation into two jets with large transverse momenta, originating from a
hard gluon exchange between the pion constituents. Both the quark and the gluon
contribution are considered and in the latter case we present calculations both
in covariant and in axial gauges. We find that the standard collinear
factorization does not hold in this reaction. The structure of non-factorizable
contributions is discussed and the results are compared with the experimental
data. Our conclusion is that the existing theoretical uncertainties do not
allow, for the time being, for a quantitative extraction of the pion
distribution amplitude.Comment: 45 pages, latex, 17 figures, final version to appear in Nuclear
Physics
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