3,258 research outputs found
Cosmology in a supersymmetric model with gauged
We consider salient cosmological features of a supersymmetric model which is
Left-Right symmetric and therefore possessing gauged symmetry. The
requirement of breaking parity and also obtaining charge preserving vacua
introduces some unique features to this model (MSLRM), resulting in a
preference for non-thermal Leptogenesis. Assuming that the model preserves TeV
scale supersymmetry, we show that the vacuum structure generically possesses
domain walls, which can serve two important purposes. They can signal a
secondary inflation required to remove unwanted relics such as gravitino and
moduli and also generate lepton asymmetry by a mechanism similar to electroweak
baryogenesis. The requirement of disappearance of domain walls imposes
constraints on the soft parameters of the theory, testable at the TeV scale. We
also propose an alternative model with spontaneous parity violation
(MSLR\rlap/P). Incorporating the same cosmological considerations in this case
entails constraints on a different set of soft parameters.Comment: 18 pages. Minor changes in text, but conclusion remains same.
Published in Phys. Rev.
Dislocation interactions and crack nucleation in a fatigued near-alpha titanium alloy
Dislocation interactions at the crack nucleation site were investigated in near-alpha titanium alloy Ti-6242Si subjected to low cycle fatigue. Cyclic plastic strain in the alloy resulted in dislocation pile-ups in the primary alpha grains, nucleated at the boundaries between the primary alpha and the two-phase regions. These two phase regions provided a barrier to slip transfer between primary alpha grains. We suggest that crack nucleation occurred near the basal plane of primary alpha grains by the subsurface double-ended pile-up mechanism first conceived by Tanaka and Mura. Superjogs on the basal dislocations were observed near the crack nucleation location. The two phase regions showed direct transmission of dislocations between secondary alpha plates, transmitted through the beta ligaments as , which then decompose into dislocation networks in the beta. The beta ligaments themselves do not appear to form an especially impenetrable barrier to slip, in agreement with the micropillar and crystal plasticity investigations of Zhang et al
Harold Jeffreys's Theory of Probability Revisited
Published exactly seventy years ago, Jeffreys's Theory of Probability (1939)
has had a unique impact on the Bayesian community and is now considered to be
one of the main classics in Bayesian Statistics as well as the initiator of the
objective Bayes school. In particular, its advances on the derivation of
noninformative priors as well as on the scaling of Bayes factors have had a
lasting impact on the field. However, the book reflects the characteristics of
the time, especially in terms of mathematical rigor. In this paper we point out
the fundamental aspects of this reference work, especially the thorough
coverage of testing problems and the construction of both estimation and
testing noninformative priors based on functional divergences. Our major aim
here is to help modern readers in navigating in this difficult text and in
concentrating on passages that are still relevant today.Comment: This paper commented in: [arXiv:1001.2967], [arXiv:1001.2968],
[arXiv:1001.2970], [arXiv:1001.2975], [arXiv:1001.2985], [arXiv:1001.3073].
Rejoinder in [arXiv:0909.1008]. Published in at
http://dx.doi.org/10.1214/09-STS284 the Statistical Science
(http://www.imstat.org/sts/) by the Institute of Mathematical Statistics
(http://www.imstat.org
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