800 research outputs found
Classical kinematics for Lorentz violation
Classical point-particle relativistic lagrangians are constructed that
generate the momentum-velocity and dispersion relations for quantum wave
packets in Lorentz-violating effective field theory.Comment: 6 pages, accepted for publication in Physics Letters
Cross Sections and Lorentz Violation
The derivation of cross sections and decay rates in the Lorentz-violating
standard-model extension is discussed. General features of the physics are
described, and some conceptual and calculational issues are addressed. As an
illustrative example, the cross section for the specific process of
electron-positron pair annihilation into two photons is obtained.Comment: 17 page
Spontaneous Lorentz Violation and Nonpolynomial Interactions
Gauge-noninvariant vector field theories with superficially nonrenormalizable
nonpolynomial interactions are studied. We show that nontrivial relevant and
stable theories have spontaneous Lorentz violation, and we present a large
class of asymptotically free theories. The Nambu-Goldstone modes of these
theories can be identified with the photon, with potential experimental
implications.Comment: 10 pages, accepted in Physics Letters
Principles for a unified picture of fermions
It is shown that a chiral SU(2) model can break Lorentz symmetry
spontaneously at the Lagrangian level when gauge bosons become massive. This
model seems to propose the principles and conceptual foundations leading to a
unified picture of fermions, and may reduce the standard theory to a far
simpler form. The model suggests describing leptons and quarks as
quasi-excitations, while electromagnetic and strong interactions as secondary
interactions mediated by Nambu-Goldstone bosons originating from spontaneous
violations of global SU(2) and rotational symmetries. Both the possibility of
observing Lorentz-violating phenomena and their magnitudes are discussed. The
model also provides an alternative scenario for baryon and lepton asymmetries
of the Universe.Comment: 11 pages, 1 figure, no change made from the previous version except
for updating the e-mail addres
Riemann-Finsler geometry and Lorentz-violating kinematics
Effective field theories with explicit Lorentz violation are intimately
linked to Riemann-Finsler geometry. The quadratic single-fermion restriction of
the Standard-Model Extension provides a rich source of pseudo-Riemann-Finsler
spacetimes and Riemann-Finsler spaces. An example is presented that is
constructed from a 1-form coefficient and has Finsler structure complementary
to the Randers structure.Comment: 19 page
Nonequilibrium Neutrino Oscillations in the Early Universe with an Inverted Neutrino-Mass Hierarchy
The annihilation of electron-positron pairs around one second after the big
bang distorts the Fermi-Dirac spectrum of neutrino energies. We determine the
distortions assuming neutrino mixing with an inverted neutrino-mass hierarchy.
Nonequilibrium thermodynamics, the Boltzmann equation, and numerical
integration are used to achieve the results. The various types of neutrino
behavior are established as a function of masses and mixing angles.Comment: 9 pages in Latex with 6 figures (10 postscript files
Nonpolynomial Normal Modes of the Renormalization Group in the Presence of a Constant Vector Potential Background
We examine the renormalization group flow in the vicinity of the free-field
fixed point for effective field theories in the presence of a constant,
nondynamical vector potential background. The interaction with this vector
potential represents the simplest possible form of Lorentz violation. We search
for any normal modes of the flow involving nonpolynomial interactions. For
scalar fields, the inclusion of the vector potential modifies the known modes
only through a change in the field strength renormalization. For fermionic
theories, where an infinite number of particle species are required in order
for nonpolynomial interactions to be possible, we find no evidence for any
analogous relevant modes. These results are consistent with the idea that the
vector potential interaction, which may be eliminated from the action by a
gauge transformation, should have no physical effects.Comment: 12 page
Lorentz Violation and the Yukawa Potential
We analyze Lorentz violations in the bosonic sector of a Yukawa-type quantum
field theory. The nonrelativistic potential may be determined to all orders in
the Lorentz violation, and we find that only specific types of modifications to
the normal Yukawa potential can be generated. The influence of this modified
potential on scattering and bounds states is calculated. These results could be
relevant to the search for new macroscopic forces, which may not necessarily be
Lorentz invariant.Comment: 10 page
Analogue Models for T and CPT Violation in Neutral-Meson Oscillations
Analogue models for CP violation in neutral-meson systems are studied in a
general framework. No-go results are obtained for models in classical mechanics
that are nondissipative or that involve one-dimensional oscillators. A complete
emulation is shown to be possible for a two-dimensional oscillator with
rheonomic constraints, and an explicit example with spontaneous T and CPT
violation is presented. The results have implications for analogue models with
electrical circuits.Comment: 9 page
Lorentz and CPT Tests in Matter and Antimatter
A review of recent theoretical work investigating tests of Lorentz and CPT
symmetry in atomic and particle systems is presented. A variety of tests in
matter and antimatter are discussed, including measurements of anomalous
magnetic moments in Penning traps, comparisons of atomic-clock transitions,
high-precision spectroscopic measurements of hydrogen and antihydrogen,
experiments with muons, experiments with mesons, and tests of Lorentz symmetry
with a spin-polarized torsion pendulum.Comment: 8 pages. Talk presented at POSITRON 03, Sandbjerg, Denmark, July 200
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