17,370 research outputs found
No-Lose `Theorem' for Parity Violating Nucleon-Nucleon Scattering Experiments
A purely left-chiral model of the weak interactions is used to show that the
total parity-violating asymmetry in quark-quark scattering must grow with
increasing energy. In the absence of other new physics, non-observation of a
large asymmetry can therefore be used to infer an upper bound on the mass scale
for new right-chiral weak vector bosons. Applying this idea to actual
nucleon-nucleon scattering requires more involved calculations, as the dominant
contribution appears to come from a component of diquark-quark scattering
related to, but not identical to, wavefunction-mixing. Earlier criticism of
this model by Simonius and Unger is refuted and a new calculation is proposed
as an additional check on the result. Finally, we argue that the so-called
`spin crisis' does not affect our conclusions. (Talk given at the BNL workshop
on future directions in particle and nuclear physics at multi-GeV hadron beam
facilities, March 4--6, 1993.)Comment: 8 pages, LaTeX, Los Alamos preprint LA-UR-93-153
Physical Degrees of Freedom for Gauge Fields and the Issue of Spin
The conflict between the physical degrees of freedom of gauge bosons and the
Lorentz group irreps naturally used to describe their couplings to matter
fields are illustrated and discussed, and applied to issues of linear and
angular momentum.Comment: 10pp., no figures, to appear in PACSpin2011 (Cairns, 20-24 June,
2011) conf. proc. (AIP
No Strings Attached: Potential vs. Interaction Energy In QCD
In infrared-stable fixed-point field theories, the interaction energy of a
test particle is proportional to the non-relativistic (heavy source)
coordinate-space potential derived from the field strength produced by that
source. This is no longer true in ultraviolet-stable fixed-point field theories
(UVSFPFT) as they may not have a finite infrared fixed point. This leads to the
possibility that UVSFPFTs may have quite conventional field strength
distributions despite the unusual spatial dependence expected for the
interaction energy.Comment: 4 pages, LaTeX, no figures, uses sprocl.sty, to appear in the
Proceedings of the Int'l Workshop on Quark Confinement and the Hadron
Spectrum II (June 26-29, 1996, Villa Olmo, Como, Italy), ed. N. Brambill
Origin of spontaneous violation of the Lorentz symmetry: Vortices in the cosmos
By carefully studying the (1,0)+(0,1) representation space for massive
particles we point to the existence of certain inherent tachyonic dispersion
relations: E^2= p^2-m^2. We put forward an interpretation that exploits these
``negative mass squared'' solutions; rotational invariance is spontaneously
broken. Relevance of these results to the vortices in the cosmos is pointed
out.
NOTE: Just as "negative energy solutions'' of Dirac equation are
re-interpreted as antiparticles, similarly the possibility exists for
re-interpreting the tachyonic dispersion relations of all (j,0)+(0,j)
representation spaces via spontaneous Lorentz symmetry breaking. In Mod. Phys.
Lett. A8:2623-2630,1993 we exhibited this explicitly for the j=1 representation
space. The interest in this old subject has grown markedly in recent years as
is evident from numerous theoretical and phenomenological works on the subject.
With this observation, we make this replacement of our paper fourteen years
after its initial publication. The Abstract and main text remain unaltered. The
title is changed to reflect the underlying physics more closely.Comment: This is an exact copy of the published paper with an extended
bibliography and a revised title. A brief note is added to point out a
systematic way to spontaneously break Lorentz symmetr
Pion LINAC as an Energy-Tagged Neutrino Source
The energy spectrum and flux of neutrinos from a linear pion accelerator are
calculated analytically under the assumption of a uniform accelerating
gradient. The energy of a neutrino from this source reacting in a detector can
be determined from timing and event position information.Comment: 16 pages, 4 figures. Replacement of Section II.D and minor
corrections elsewhere. The basic point and conclusions of the paper are
unchanged. Phys. Rev. ST Accel. Beams 11,124701 (2008); Erratum submitte
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