1,400 research outputs found
Towards the Theory of Diffractive DIS
The large rapidity gap events, observed at HERA, have changed considerably
our physical picture of deep inelastic scattering during the past years. We
review the present theoretical understanding of diffractive DIS with emphasis
on the close relation to inclusive DIS. This includes success and limitations
of the leading twist description, the connection between diffractive and
inclusive parton distributions in the semiclassical approach, the colour
structure of the proton and comparison with data. The progress report concludes
with a list of open questions.Comment: 19 pages, 8 figures; presented at `New Trends in HERA Physics',
Ringberg Workshop, June 199
Combined analysis of diffractive and inclusive structure functions in the semiclassical framework
Small-x DIS is described as the scattering of a partonic fluctuation of the
photon off a superposition of target color fields. Diffraction occurs if the
emerging partonic state is in a color singlet. Introducing a specific model for
the averaging over all relevant color field configurations, both diffractive
and inclusive parton distributions at some low scale Q_0^2 can be calculated. A
conventional DGLAP analysis results in a good description of diffractive and
inclusive structure functions at higher values of Q^2.Comment: 3 pages LaTeX, 3 figures, talk presented at the 7th International
Workshop on Deep Inelastic Scattering and QCD (DIS99), Zeuthen, Germany,
April 19-23, 199
Quark Lepton Mass Hierarchies and the Baryon Asymmetry
The mass hierarchies of quarks and charged leptons as well as a large
\n_\m-\n_\t mixing angle are naturally explained by the Frogatt-Nielsen
mechanism with a nonparallel family structure of chiral charges. We extend this
mechanism to right-handed neutrinos. Their out-of-equilibrium decay generates a
cosmological baryon asymmetry whose size is quantized in powers of the
hierarchy parameter \e^2. For the simplest hierarchy pattern the neutrino
mass \bar{m}_\n= (m_{\n_\m}m_{\n_\t})^{1/2} \sim 10^{-2} eV, which is
inferred from present indications for neutrino oscillations, implies a baryon
asymmetry . The corresponding baryogenesis temperature is
GeV.Comment: 7 page
Neutrino masses and the baryon asymmetry
Due to sphaleron processes in the high-temperature symmetric phase of the
standard model the cosmological baryon asymmetry is related to neutrino
properties. For hierarchical neutrino masses, with broken at the
unification scale GeV, the observed baryon
asymmetry can be naturally explained by the decay of
heavy Majorana neutrinos. We illustrate this mechanism with two models of
neutrino masses, consistent with the solar and atmospheric neutrino anomalies,
which are based on the two symmetry groups and
.
We also review related cosmological bounds on Majorana neutrino masses and
the use of Boltzmann equations.Comment: 45 pages, 12 figure
High- Jets in Diffractive Electroproduction
The diffractive production of high- jets in deep-inelastic
scattering is studied in the semiclassical approach. The -spectra of
and diffractive final states are found to be
qualitatively different. For final states, which are produced by
`hard' colour-singlet exchange, the -spectrum is much softer than
for final states, where the colour neutralization is `soft'.
Furthermore, the two different final states can be clearly distinguished by
their diffractive mass distributions.Comment: 9 pages, latex, 5 figure
Quantum mechanics of baryogenesis
The cosmological baryon asymmetry can be explained as remnant of heavy
Majorana neutrino decays in the early universe. We study this
out-of-equilibrium process by means of Kadanoff-Baym equations which are solved
in a perturbative expansion. To leading order the problem is reduced to solving
a set of Boltzmann equations for distribution functions.Comment: 12 pages, 2 figures, typos corrected. To be published in Physics
Letter
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