101 research outputs found
EVIDENCE-BASED RELATIONSHIP BETWEEN THE LEVELS OF IL-6, VECF, sFas, FasL AND ENDOSTATIN IN PATIENTS WITH OVARIAN NEOPLASMS
The paper deals with the study of the factors that regulate apoptosis and angiogenesis, by using biomolecular methods in patients with ovarian neoplasms. The investigation of these factors will furnish insights into the essence of the abnormalities underlying these diseases
Photon & Axion Oscillation In a Magnetized Medium: A Covariant Treatment
Pseudoscalar particles, with almost zero mass and very weak coupling to the
visible matter, arise in many extensions of the standard model of particle
physics. Their mixing with photons in the presence of an external magnetic
field leads to many interesting astrophysical and cosmological consequences.
This mixing depends on the medium properties, the momentum of the photon and
the background magnetic field. Here we give a general treatment of
pseudoscalar-photon oscillations in a background magnetic field, taking the
Faraday term into account. We give predictions valid in all regimes, under the
assumption that the frequency of the wave is much higher than the plasma
frequency of the medium. At sufficiently high frequencies, the Faraday effect
is negligible and we reproduce the standard pseudoscalar-photon mixing
phenomenon. However at low frequencies, where Faraday effect is important, the
mixing formulae are considerably modified. We explicitly compute the
contribution due to the longitudinal mode of the photon and show that it is
negligible.Comment: 16 pages, no figure
libepa -- a C++/Python library for calculations of cross sections of ultraperipheral collisions
The library provides a set of C++/Python functions for computing cross
sections of ultraperipheral collisions of high energy particles under the
equivalent photons approximation. Cross sections are represented through
multiple integrals over the phase space. The integrals are calculated through
recurrent application of algorithms for one dimensional integration. The paper
contains an introduction to the theory of ultraperipheral collisions, discusses
the library approach and provides a few examples of calculations.Comment: 25 pages, 6 figures, 1 table. See the arXiv archive for supplementary
materials (code
Weak interaction corrections to muon pair production via the photon fusion at the LHC
Analytical formulas describing the correction due to the boson exchange
to the cross section of the reaction are
presented. When the invariant mass of the produced muon pair and its total transverse momentum is large, the correction is
of the order of 20%.Comment: 17 pages, 5 figure
On production of heavy charged particles in fusion at planned colliders
Production of heavy fermions in ultraperipheral collisions () and the semiexclusive reaction () is considered. Differential
and total cross sections for the energies of the planned colliders are
presented.Comment: 8 pages, 4 figures, 2 table
scattering at the LHC with the lepton pair production and one proton tagging
Analytical formulas for the cross section of the reaction are presented. Fiducial cross sections are compared with those
measured recently by the ATLAS collaboration.Comment: 12 pages, 1 figur
Moderate Supersymmetric CP Violation
It is well known that supersymmetry (SUSY) gives neutron and electron
electric dipole moments ( and ) which are too large by about
. If we assume a SUSY model cannot contain fine-tunings or large mass
scales, then one must require that the SUSY breaking mechanism give real soft
breaking parameters, in which case the minimal SUSY model has no violation
other than from the CKM matrix (besides possible strong violating
effects). We show that in non-minimal SUSY models, a moderate amount of
violation can be induced through one loop corrections to the scalar potential,
giving an effective phase of order , and thus implying and
can be near their current experimental bounds . This moderate amount
of SUSY violation could also prove important for models of electroweak
baryogenesis. We illustrate our results with a specific model.Comment: 19pp plain LATEX, 1 fig (by EMAIL request), TRI-PP-93-86. (Some
clarifying comments about renormalizability added--version to appear in Phys.
Rev. D
Cosmological constraints on R-parity violation from neutrino decay
If the neutrino mass is non-zero, as hinted by several experiments, then
R-parity-violating supersymmetric Yukawa couplings can drive a heavy neutrino
decay into lighter states. The heavy neutrino may either decay radiatively into
a lighter neutrino, or it may decay into three light neutrinos through a
Z-mediated penguin. For a given mass of the decaying neutrino, we calculate its
lifetime for the various modes, each mode requiring certain pairs of
R-parity-violating couplings be non-zero. We then check whether the calculated
lifetimes fall in zones allowed or excluded by cosmological requirements. For
the latter case, we derive stringent new constraints on the corresponding
products of R-parity-violating couplings for given values of the decaying
neutrino mass.Comment: 13 pages, Latex, uses axodraw.sty; version to appear in Physical
Review
Solving the mu problem with a heavy Higgs boson
We discuss the generation of the mu-term in a class of supersymmetric models
characterized by a low energy effective superpotential containing a term lambda
S H_1 H_2 with a large coupling lambda~2. These models generically predict a
lightest Higgs boson well above the LEP limit of 114 GeV and have been shown to
be compatible with the unification of gauge couplings. Here we discuss a
specific example where the superpotential has no dimensionful parameters and we
point out the relation between the generated mu-term and the mass of the
lightest Higgs boson. We discuss the fine-tuning of the model and we find that
the generation of a phenomenologically viable mu-term fits very well with a
heavy lightest Higgs boson and a low degree of fine-tuning. We discuss
experimental constraints from collider direct searches, precision data, thermal
relic dark matter abundance, and WIMP searches finding that the most natural
region of the parameter space is still allowed by current experiments. We
analyse bounds on the masses of the superpartners coming from Naturalness
arguments and discuss the main signatures of the model for the LHC and future
WIMP searches.Comment: Extended discussion of the LHC phenomenology, as published on JHEP
plus an addendum on the existence of further extremal points of the
potential. 47 pages, 16 figure
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