519 research outputs found
On Generalized Self-Duality Equations Towards Supersymmetric Quantum Field Theories Of Forms
We classify possible `self-duality' equations for p-form gauge fields in
space-time dimension up to D=16, generalizing the pioneering work of Corrigan
et al. (1982) on Yang-Mills fields (p=1) for D from 5 to 8. We impose two
crucial requirements. First, there should exist a 2(p+1)-form T invariant under
a sub-group H of SO(D). Second, the representation for the SO(D) curvature of
the gauge field must decompose under H in a relevant way. When these criteria
are fulfilled, the `self-duality' equations can be candidates as gauge
functions for SO(D)-covariant and H-invariant topological quantum field
theories. Intriguing possibilities occur for dimensions greater than 9, for
various p-form gauge fields.Comment: 20 pages, Late
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Highest-weight representations of Brocherd`s algebras
General features of highest-weight representations of Borcherd`s algebras are described. to show their typical features, several representations of Borcherd`s extensions of finite-dimensional algebras are analyzed. Then the example of the extension of affine- su(2) to a Borcherd`s algebra is examined. These algebras provide a natural way to extend a Kac-Moody algebra to include the hamiltonian and number-changing operators in a generalized symmetry structure
Solving Gauge Invariant Systems without Gauge Fixing: the Physical Projector in 0+1 Dimensional Theories
The projector onto gauge invariant physical states was recently constructed
for arbitrary constrained systems. This approach, which does not require gauge
fixing nor any additional degrees of freedom beyond the original ones---two
characteristic features of all other available methods for quantising
constrained dynamics---is put to work in the context of a general class of
quantum mechanical gauge invariant systems. The cases of SO(2) and SO(3) gauge
groups are considered specifically, and a comprehensive understanding of the
corresponding physical spectra is achieved in a straightforward manner, using
only standard methods of coherent states and group theory which are directly
amenable to generalisation to other Lie algebras. Results extend by far the few
examples available in the literature from much more subtle and delicate
analyses implying gauge fixing and the characterization of modular space.Comment: 32 pages, LaTeX fil
Rayleigh-Lidar Determinations of the Vertical Wavelength of Mesospheric Gravity Wave
Atmospheric structures have been observed in the Rayleigh lidar data acquired between 1993 and 2004 at Utah State University (USU). The observations pertain to the density and temperature in the mesosphere between 45 and 90 km altitude. The structures referred to arise from monochromatic Atmospheric Gravity Waves (AGWs). Previous analysis of these data have searched for and found a spectrum with a peak in the vertical wavelength 12â16 km. It has been suggested by other researchers using other types of data that there may be another peak in the spectrum at shorter wavelengths. For this study the lidar data were re- analyzed to search for such waves. To do this, the altitude resolution was reduced from 3 km to 600 m. This enabled the shortest wavelength AGW that can be examined to be reduced from 6 km to ~1.2 km, thereby significantly extending the spectrum investigated. Two additional peaks in the spectrum were found at 1.25â1.75 and 3.0â4.0 km
Triplet Leptogenesis in Left-Right Symmetric Seesaw Models
We discuss scalar triplet leptogenesis in a specific left-right symmetric
seesaw model. We show that the Majorana phases that are present in the model
can be effectively used to saturate the existing upper limit on the
CP-asymmetry of the triplets. We solve the relevant Boltzmann equations and
analyze the viability of triplet leptogenesis. It is known for this kind of
scenario that the efficiency of leptogenesis is maximal if there exists a
hierarchy between the branching ratios of the triplet decays into leptons and
Higgs particles. We show that triplet leptogenesis typically favors branching
ratios with not too strong hierarchies, since maximal efficiency can only be
obtained at the expense of suppressed CP-asymmetries.Comment: 16 pages, 5 figures, published versio
Resource allocation in auditory processing of emphatically stressed stimuli in aphasia
Kimelman and McNeil (1987) suggested that improved auditory comprehension for emphatically stressed information might be attributed to recruitment of additional processing resources. This study investigated effects of emphatic stress when it was applied to target words during a semantic judgement task on the auditory processing of non-stressed targets for a lexical decision task. Response time and accuracy were analysed for this dual-task experiment. It was first established that the stimuli contained appropriately placed stressed lexical items and that all subjects benefited from the emphatic stress. Next it was established that all subjects were able to voluntarily trade processing resources in the dual task under investigation, and were able to generate a performance operating curve (POC). Normal subjects showed the predicted performance decrement on the non-stressed word in the context of the preceding stressed word; subjects with aphasia did not. Results are discussed relative to resource allocation theory with normal subjects, and a working memory explanation for aphasic subjects' performance
Color embeddings, charge assignments, and proton stability in unified gauge theories
Three problems in hypothetical unified theories of electromagnetic, weak, and strong interactions are discussed here. First, the problem of embedding color in any simple gauge group is solved, and a complete classification of theories where the fermion color is restricted to 1^c, 3^c, and 3^c of SU_3^c is given. Generalizations are also indicated. Second, an unbroken U_1 generated by electric charge is embedded into each of the above theories and the charge assignments analyzed. Third, the general problem of stabilizing the proton by a suitable atomic mass number A is studied for the same set of theories. It is always possible to define A if the gauge group is not too small. In many of these theories there must be fermions with weird values of A: leptons with Aâ 0 and quarks with Aâ 1/3. Examples are discussed. Some future directions of research are indicated
A SUSY SO(10) GUT with an Intermediate Scale
We examine a superpotential for an SO(10) GUT and show that if the parameters
of the superpotential are in a certain region, the SO(10) GUT has an
intermediate symmetry which breaks down to the group of the
Standard Model at an intermediate scale GeV. In the model by the
breakdown of the symmetry right-handed neutrinos acquire mass of the
intermediate scale through a renormalizable Yukawa coupling.Comment: 36 pages, LaTeX, I fixed several mistakes as follows. 1. delete
Appendix D because there was a mistake and if I fix it, it becomes nothing
interesting. 2. matrix M(2,1,\pm 1/2) at the last half of the section 4 is
changed. COnsequent result is not essentially changed. 3. several typological
errors are fixe
Mersenne Primes, Polygonal Anomalies and String Theory Classification
It is pointed out that the Mersenne primes and associated
perfect numbers play a significant role in string
theory; this observation may suggest a classification of consistent string
theories.Comment: 10 pages LaTe
See-Saw Masses for Quarks and Leptons in SU(5)
We build on a recent paper by Grinstein, Redi and Villadoro, where a see-saw
like mechanism for quark masses was derived in the context of spontaneously
broken gauged flavour symmetries. The see-saw mechanism is induced by heavy
Dirac fermions which are added to the Standard Model spectrum in order to
render the flavour symmetries anomaly-free. In this letter we report on the
embedding of these fermions into multiplets of an SU(5) grand unified theory
and discuss a number of interesting consequences.Comment: 15 pages, 4 figures (v3: outline restructured, modified mechanism to
cancel anomalies
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