55 research outputs found
Down Type Isosinglet Quarks in ATLAS
We evaluate the discovery reach of the ATLAS experiment for down type
isosinglet quarks, , using both their neutral and charged decay channels,
namely the process with subsequent decays resulting in
, and final states.
The integrated luminosity required for observation of a heavy quark is
estimated for a mass range between 600 and 1000 GeV using the combination of
results from different search channels.Comment: 12 page
Avenues of cognition of nongravitational local gauge field theories
This controbution is devoted to present basic fearures of a unifying local gauge field theory, prevailing up to a mass scale of approximately 10 16 GeV , allowing the neglect of gravitational curvature effects – indicated by the attribute : ’nongravitational’ in the title above
Nonlinear QED and Physical Lorentz Invariance
The spontaneous breakdown of 4-dimensional Lorentz invariance in the
framework of QED with the nonlinear vector potential constraint
A_{\mu}^{2}=M^{2}(where M is a proposed scale of the Lorentz violation) is
shown to manifest itself only as some noncovariant gauge choice in the
otherwise gauge invariant (and Lorentz invariant) electromagnetic theory. All
the contributions to the photon-photon, photon-fermion and fermion-fermion
interactions violating the physical Lorentz invariance happen to be exactly
cancelled with each other in the manner observed by Nambu a long ago for the
simplest tree-order diagrams - the fact which we extend now to the one-loop
approximation and for both the time-like (M^{2}>0) and space-like (M^{2}<0)
Lorentz violation. The way how to reach the physical breaking of the Lorentz
invariance in the pure QED case taken in the flat Minkowskian space-time is
also discussed in some detail.Comment: 16 pages, 2 Postscript figures to be published in Phys. Rev.
Thermodynamic instabilities in one dimensional particle lattices: a finite-size scaling approach
One-dimensional thermodynamic instabilities are phase transitions not
prohibited by Landau's argument, because the energy of the domain wall (DW)
which separates the two phases is infinite. Whether they actually occur in a
given system of particles must be demonstrated on a case-by-case basis by
examining the (non-) analyticity properties of the corresponding transfer
integral (TI) equation. The present note deals with the generic Peyrard-Bishop
model of DNA denaturation. In the absence of exact statements about the
spectrum of the singular TI equation, I use Gauss-Hermite quadratures to
achieve a single-parameter-controlled approach to rounding effects; this allows
me to employ finite-size scaling concepts in order to demonstrate that a phase
transition occurs and to derive the critical exponents.Comment: 5 pages, 6 figures, subm. to Phys. Rev.
Conservation laws and scattering for de Sitter classical particles
Starting from an intrinsic geometric characterization of de Sitter timelike
and lightlike geodesics we give a new description of the conserved quantities
associated with classical free particles on the de Sitter manifold. These
quantities allow for a natural discussion of classical pointlike scattering and
decay processes. We also provide an intrinsic definition of energy of a
classical de Sitter particle and discuss its different expressions in various
local coordinate systems and their relations with earlier definitions found in
the literature.Comment: 25 pages, 1 figur
An updated analysis of eps'/eps in the standard model with hadronic matrix elements from the chiral quark model
We discuss the theoretical and experimental status of the CP violating ratio
eps'/eps. We revise our 1997 standard-model estimate-based on hadronic matrix
elements computed in the chiral quark model up to O(p^4) in the chiral
expansion-by including an improved statistical analysis of the uncertainties
and updated determination of the Cabibbo-Kobayashi-Maskawa elements and other
short-distance parameters. Using normal distributions for the experimental
input data we find Re eps'/eps = (2.2 \pm 0.8) x 10^{-3}, whereas a flat
scanning gives 0.9 x 10^{-3} < Re eps'/eps < 4.8 x 10^{-3}. Both results are in
agreement with the current experimental data. The key element in our estimate
is, as before, the fit of the Delta I=1/2 rule, which allows us to absorb most
of the theoretical uncertainties in the determination of the model-dependent
parameters in the hadronic matrix elements. Our semi-phenomenological approach
leads to numerical stability against variations of the renormalization scale
and scheme dependence of the short- and long-distance components. The same
dynamical mechanism at work in the selection rule also explains the larger
value obtained for \ratio with respect to other estimates. A coherent picture
of K -> pi pi decays is thus provided.Comment: 15 pages, 11 figures, RevTeX, discussion updated, refs adde
Moduli in Exceptional SUSY Gauge Theories
The low energy structures of N=1 supersymmetric models with E_6, F_4 and E_7
gauge groups and fundamental irrep matter contents are studied herein. We
identify sets of gauge invariant composites which label all flat directions in
the confining/Higgs phases of these theories. The impossibility of mapping
several of these primary operators rules out previously conjectured exceptional
self duals reported in the literature.Comment: 20 pages, harvmac and tables macro
Sterile Neutrinos in E_6 and a Natural Understanding of Vacuum Oscillation Solution to the Solar Neutrino Puzzle
If Nature has chosen the vacuum oscillation solution to the Solar neutrino
puzzle, a key theoretical challenge is to understand the extreme smallness of
the () required for the purpose.
We find that in a class of models such as [SU(3)]^3 or its parent group E_6,
which contain one sterile neutrino, for each family, the is proportional to the cube of the lepton Yukawa
coupling. Therefore fitting the atmospheric neutrino data then predicts the
mass difference square to be , where the atmospheric neutrino data is assumed to be
solved via the oscillation. This provides a natural
explanation of the vacuum oscillation solution to the solar neutrino problem.Comment: 7 pages, UMD-PP-99-109; new references added; no other chang
Heavy quark supermultiplet excitations
Lorentz covariant wave functions for meson and baryon supermultiplets are
simply derived by boosting representations corresponding to
multiquark systems at rest.Comment: 12 pages (Revtex), UTAS-PHYS-93-4
Leptogenesis and Neutrino Oscillations Within A Predictive G(224)/SO(10)-Framework
A framework based on an effective symmetry that is either G(224)= SU(2)_L x
SU(2)_R xSU(4)^c or SO(10) has been proposed (a few years ago) that
successfully describes the masses and mixings of all fermions including
neutrinos, with seven predictions, in good accord with the data. Baryogenesis
via leptogenesis is considered within this framework by allowing for natural
phases (~ 1/20-1/2) in the entries of the Dirac and Majorana mass-matrices. It
is shown that the framework leads quite naturally, for both thermal as well as
non-thermal leptogenesis, to the desired magnitude for the baryon asymmetry.
This result is obtained in full accord with the observed features of the
atmospheric and solar neutrino oscillations, as well as with those of the quark
and charged lepton masses and mixings, and the gravitino-constraint. Hereby one
obtains a unified description of fermion masses, neutrino oscillations and
baryogenesis (via leptogenesis) within a single predictive framework.Comment: Efficiency factor updated, some clarifications and new references
added. 19 page
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