3,494 research outputs found
Coherent pion production by neutrinos on nuclei
The main part of coherent pion production by neutrinos on nuclei is
essentially determined by PCAC, provided that the leptonic momentum transferred
square Q^2 remains sufficiently small. We give the formulas for the charged and
neutral current cross sections, including also the small non-PCAC transverse
current contributions and taking into account the effect of the \mu^- mass. Our
results are compared with the experimental ones and other theoretical
treatments.Comment: 18 pages, 4 figure
From the Birkhoff-Gustavson normalization to the Bertrand-Darboux integrability condition
The Bertrand-Darboux integrability condition for a certain class of perturbed
harmonic oscillators is studied from the viewpoint of the
Birkhoff-Gustavson(BG)-normalization: By solving an inverse problem of the
BG-normalization on computer algebra, it is shown that if the perturbed
harmonic oscillators with a homogeneous-{\it cubic} polynomial potential and
with a homogeneous-{\it quartic} polynomial potentials admit the same
BG-normalization up to degree-4 then both oscillators satisfy the
Bertrand-Darboux integrability condition.Comment: 23 pages, LaTeX (iop.sty), typos and Appendix adde
Light Gluino Constituents of Hadrons and a Global Analysis of Hadron Scattering Data
Light strongly interacting supersymmetric particles may be treated as
partonic constituents of nucleons in high energy scattering processes. We
construct parton distribution functions for protons in which a light gluino is
included along with standard model quark, antiquark, and gluon constituents. A
global analysis is performed of a large set of data from deep-inelastic lepton
scattering, massive lepton pair and vector boson production, and hadron jet
production at large values of transverse momentum. Constraints are obtained on
the allowed range of gluino mass as a function of the value of the strong
coupling strength alpha_s(M_Z) determined at the scale of the Z boson mass. We
find that gluino masses as small as 10 GeV are admissible provided that
alpha_s(M_Z) \ge 0.12. Current hadron scattering data are insensitive to the
presence of gluinos heavier than ~ 100 - 150 GeV.Comment: 31 pages, 12 figures, RevTe
Stein structures: existence and flexibility
This survey on the topology of Stein manifolds is an extract from our recent
joint book. It is compiled from two short lecture series given by the first
author in 2012 at the Institute for Advanced Study, Princeton, and the Alfred
Renyi Institute of Mathematics, Budapest.Comment: 29 pages, 11 figure
LHC as and Collider
We propose an experiment at the LHC with leading neutron production.The
latter can be used to extract from it the total cross-sections. With
two leading neutrons we can get access to the total
cross-sections. In this note we give some estimates and discuss related
problems and prospects.Comment: 22 pages, 18 figures, 8 tables, to be publishe
Review of factorization breaking in diffractive photoproduction of dijets
After the final analyses of the H1 and ZEUS collaborations for the
diffractive photoproduction of dijets have appeared, we have recalculated these
cross sections in next-to-leading order (NLO) of perturbative QCD to see
whether they can be interpreted consistently. The results of these calculations
are compared to the data of both collaborations. We find that at NLO the cross
sections disagree with the data, showing that factorization breaking occurs at
this order. If direct and resolved contributions are both suppressed by the
same amount, the global suppression factor depends on the transverse-energy cut
and is 0.42 for the H1 and 0.71 for the ZEUS analysis. However, by suppressing
only the resolved contribution by a factor of approximately three, also
reasonably good agreement with all the data is found. The size of the
factorization breaking effects for resolved photons agrees with
absorptive-model predictions.Comment: 22 pages, 2 tables, 8 figures. Invited brief review for Modern
Physics Letters
Factorization Breaking in Dijet Photoproduction with a Leading Neutron
The production of dijets with a leading neutron in ep-interactions at HERA is
calculated in leading order and next-to-leading order of perturbative QCD using
a pion-exchange model. Differential cross sections for deep-inelastic
scattering (DIS) and photoproduction are presented as a function of several
kinematic variables. By comparing the theoretical predictions for DIS dijets to
recent H1 data, the pion flux factor together with the parton distribution
functions of the pion is determined. The dijet cross sections in
photoproduction show factorization breaking if compared to the H1
photoproduction data. The suppression factor is S = 0.48 (0.64) for resolved
(global) suppression.Comment: 16 pages, 5 figure
Testing the dynamics of high energy scattering using vector meson production
I review work on diffractive vector meson production in photon-proton
collisions at high energy and large momentum transfer, accompanied by proton
dissociation and a large rapidity gap. This process provides a test of the high
energy scattering dynamics, but is also sensitive to the details of the
treatment of the vector meson vertex.
The emphasis is on the description of the process by a solution of the
non-forward BFKL equation, i.e. the equation describing the evolution of
scattering amplitudes in the high-energy limit of QCD. The formation of the
vector meson and the non-perturbative modeling needed is also briefly
discussed.Comment: 17 pages, 8 figures. Brief review to appear in Mod. Phys. Lett.
The energy dependence of the hard exclusive diffractive processes in pQCD as the function of momentum transfer
We predict the dependence on energy of photo(electro) production processes:
with large rapidity gap at small x and large
momentum transferred to in pQCD. Here V is a heavy quarkonium
() or longitudinally polarized light vector meson (in the
electroproduction processes), etc. In the kinematics of HERA we calculate the
dependence on energy of cross sections of these processes as the function of
momentum transfer , photon virtuality and/or quarkonium mass. In the
kinematical region the nontrivial energy dependence
of the cross section for the vector meson production due to the photon
scattering off a parton follows within QCD from the summing of the double
logarithmic terms. In the second regime within DGLAP
approximation in all orders of perturbation theory the
elastic cross section is energy independent. We show that the correct account
of the double logarithmic terms and of the gluon radiation including
kinematical constraints removes the disagreement between pQCD calculations and
recent HERA experimental data. The explicit formula for the dependence of the
differential cross section of these
processes on is obtained. We show that perturbative Pomeron
type behavior may reveal itself only at energies significantly larger than
those available at HERA. In addition we evaluate the energy dependence of DCVS
processes.Comment: 22 pages, 4 figure
Non-global logarithms and jet algorithms in high-pT jet shapes
We consider jet-shape observables of the type proposed recently, where the
shapes of one or more high-pT jets, produced in a multi-jet event with definite
jet multiplicity, may be measured leaving other jets in the event unmeasured.
We point out the structure of the full next-to-leading logarithmic resummation
specifically including resummation of non-global logarithms in the leading-Nc
limit and emphasising their properties. We also point out differences between
jet algorithms in the context of soft gluon resummation for such observables.Comment: 22 pages, 4 figures. Title and a few words changed. Several typos
corrected. Version accepted by JHE
- …