994 research outputs found
Odd C-P contributions to diffractive processes
We investigate contributions to diffractive scattering, which are odd under
C- and P-parity. Comparison of p- and p-p scattering indicates that
these odderon contributions are very small and we show how a diquark clustering
in the proton can explain this effect. A good probe for the odderon exchange is
the photo- and electroproduction of pseudo-scalar mesons. We concentrate on the
pi^0 and show that the quasi elastic pi^0-production is again strongly
suppressed for a diquark structure of the proton whereas the cross sections for
diffractive proton dissociation are larger by orders of magnitude and rather
independent of the proton structure.Comment: 18 pages, LaTex2e, graphicx package, 14 eps figures include
Log(1/x) Gluon Distribution and Structure Functions in the Loop-Loop Correlation Model
We consider the interaction of the partonic fluctuation of a scalar
``photon'' with an external color field to calculate the leading and
next-to-leading order gluon distribution of the proton following the work done
by Dosch-Hebecker-Metz-Pirner. We relate these gluon distributions to the short
and long distance behavior of the cross section of an adjoint dipole scattering
off a proton. The leading order result is a constant while the next-to-leading
order result shows a ln(1/x) enhancement at small x. To get numerical results
for the gluon distributions at the initial scale Q^2_0=1.8 GeV^2, we compute
the adjoint dipole-proton cross section in the loop-loop correlation model.
Quark distributions at the same initial scale are parametrized according to
Regge theory. We evolve quark and gluon distributions to higher Q^2 values
using the DGLAP equation and compute charm and proton structure functions in
the small-x region for different Q^2 values.Comment: 13 pages, 10 figures,revised version,references added, typos
corrected, to be published in Eur. Phys. Journal
Conducting a Fraud Examination on Your Fraud Examination Students
The purpose of this paper is to discuss a fraud examination that occurred during a fraud examination course. The examination was not what one would first imagine. It was not an examination conducted by the students as part of the course requirements. Instead, it was an examination performed by the instructor on his students.
This paper will note how the investigation of the students relates to common components of frauds, attributes of the perpetrators, investigation methods utilized, the final resolution of this investigation, and what I might do different in future investigations
Kinematical and Dynamical Aspects of Higher-Spin Bound-State Equations in Holographic QCD
In this paper we derive holographic wave equations for hadrons with arbitrary
spin starting from an effective action in a higher-dimensional space asymptotic
to anti-de Sitter (AdS) space. Our procedure takes advantage of the local
tangent frame, and it applies to all spins, including half-integer spins. An
essential element is the mapping of the higher-dimensional equations of motion
to the light-front Hamiltonian, thus allowing a clear distinction between the
kinematical and dynamical aspects of the holographic approach to hadron
physics. Accordingly, the non-trivial geometry of pure AdS space encodes the
kinematics, and the additional deformations of AdS space encode the dynamics,
including confinement. It thus becomes possible to identify the features of
holographic QCD which are independent of the specific mechanisms of conformal
symmetry breaking. In particular, we account for some aspects of the striking
similarities and differences observed in the systematics of the meson and
baryon spectra.Comment: 43 page
Hadron Spectroscopy and Dynamics from Light-Front Holography and Conformal Symmetry
To a first semiclassical approximation one can reduce the multi-parton
light-front problem in QCD to an effective one-dimensional quantum field
theory, which encodes the fundamental conformal symmetry of the classical QCD
Lagrangian. This procedure leads to a relativistic light-front wave equation
for arbitrary spin which incorporates essential spectroscopic and
non-perturbative dynamical features of hadron physics. The mass scale for
confinement and higher dimensional holographic mapping to AdS space are also
emergent properties of this framework.Comment: 11 pages, 6 figures. Invited plenary talk, presented by GdT at the
13th International Conference on Meson-Nucleon Physics and the Structure of
the Nucleon (MENU 2013), Rome, September 30 - October 4, 201
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