54,091 research outputs found
CP violation with a dynamical Higgs
We determine the complete set of independent gauge and gauge-Higgs CP-odd
effective operators for the generic case of a dynamical Higgs, up to four
derivatives in the chiral expansion. The relation with the linear basis of
dimension six CP-odd operators is clarified. Phenomenological applications
include bounds inferred from electric dipole moment limits, and from present
and future collider data on triple gauge coupling measurements and Higgs
signals.Comment: 41 pages, 3 figures; V2: citations added, typos corrected, version
published on JHE
Neutrinoless double-beta decay. A brief review
In this brief review we discuss the generation of Majorana neutrino masses
through the see-saw mechanism, the theory of neutrinoless double-beta decay,
the implications of neutrino oscillation data for the effective Majorana mass,
taking into account the recent Daya Bay measurement of theta_13, and the
interpretation of the results of neutrinoless double-beta decay experiments.Comment: 22 page
Number and length of attractors in a critical Kauffman model with connectivity one
The Kauffman model describes a system of randomly connected nodes with
dynamics based on Boolean update functions. Though it is a simple model, it
exhibits very complex behavior for "critical" parameter values at the boundary
between a frozen and a disordered phase, and is therefore used for studies of
real network problems. We prove here that the mean number and mean length of
attractors in critical random Boolean networks with connectivity one both
increase faster than any power law with network size. We derive these results
by generating the networks through a growth process and by calculating lower
bounds.Comment: 4 pages, no figure, no table; published in PR
Spectral Evolution of Two High-Energy Gamma-Ray Bursts
The prompt emission of the gamma-ray bursts is found to be very energetic,
releasing ~10^51 ergs in a flash. However, their emission mechanism remains
unclear and understanding their spectra is a key to determining the emission
mechanism. Many GRB spectra have been analyzed in the sub-MeV energy band, and
are usually well described with a smoothly broken power-law model. We present a
spectral analysis of two bright bursts (GRB910503 and GRB930506), using BATSE
and EGRET spectra that cover more than four decades of energy (30 keV - 200
MeV). Our results show time evolutions of spectral parameters (low-energy &
high-energy photon indices and break energy) that are difficult to reconcile
with a simple shock-acceleration model.Comment: 8 pages, 2 figures, to appear in the proceedings of "Astrophysical
Particle Acceleration in Geospace and Beyond", Chattanooga, 2002, AGU
monograp
Neutral current (anti)neutrino scattering: relativistic mean field and superscaling predictions
We evaluate the neutral current quasi-elastic neutrino cross section within
two nuclear models: the SuSA model, based on the superscaling behavior of
electron scattering data, and the RMF model, based on relativistic mean field
theory. We also estimate the ratio and
compare with the MiniBooNE experimental data, performing a fit of the
parameters and within the two models. Finally, we present our
predictions for antineutrino scattering.Comment: 15 pages, 4 figure
Disentangling a dynamical Higgs
The pattern of deviations from Standard Model predictions and couplings is
different for theories of new physics based on a non-linear realization of the
gauge symmetry breaking and those assuming a linear
realization. We clarify this issue in a model-independent way via its effective
Lagrangian formulation in the presence of a light Higgs particle, up to first
order in the expansions: dimension-six operators for the linear expansion and
four derivatives for the non-linear one. Complete sets of pure gauge and
gauge-Higgs operators are considered, implementing the renormalization
procedure and deriving the Feynman rules for the non-linear expansion. We
establish the theoretical relation and the differences in physics impact
between the two expansions. Promising discriminating signals include the
decorrelation in the non-linear case of signals correlated in the linear one:
some pure gauge versus gauge-Higgs couplings and also between couplings with
the same number of Higgs legs. Furthermore, anomalous signals expected at first
order in the non-linear realization may appear only at higher orders of the
linear one, and vice versa. We analyze in detail the impact of both type of
discriminating signals on LHC physics.Comment: Version published in JHE
Few-anyon systems in a parabolic dot
The energy levels of two and three anyons in a two-dimensional parabolic
quantum dot and a perpendicular magnetic field are computed as power series in
1/|J|, where J is the angular momentum. The particles interact repulsively
through a coulombic (1/r) potential. In the two-anyon problem, the reached
accuracy is better than one part in 10^5. For three anyons, we study the
combined effects of anyon statistics and coulomb repulsion in the ``linear''
anyonic states.Comment: LaTeX, 6 pages, 4 postscript figure
- …