Conceivable Lorentzviolating effects in the neutrino sector remain a research area of great general interest, as they touch upon the very foundations on which the Standard Model and our general understanding of fundamental interactions are laid. Here, we investigate the relation of Lorentz violation in the neutrino sector in light of the fact that neutrinos and the corresponding lefthanded charged leptons form [Formula: see text] doublets under the electroweak gauge group. Lorentzviolating effects thus cannot be fully separated from questions related to gauge invariance. The model dependence of the effective interaction Lagrangians used in various recent investigations is explored with a special emphasis on neutrino splitting, otherwise known as the neutrinopair Cerenkov radiation and vacuumpair emission (electron–positronpair Cerenkov radiation). We highlight two scenarios in which Lorentzviolating effects do not necessarily also break electroweak gauge invariance. The first of these involves a restricted set of gauge transformations, a subgroup of [Formula: see text], while in the second where differential Lorentz violation is exclusively introduced by the mixing of the neutrino flavor and mass eigenstates. Our study culminates in a model which fully preserves [Formula: see text] gauge invariance, involves flavordependent Lorentzbreaking parameters, and still allows for Cerenkovtype decays to proceed.
more »
« less
Physical effects of the gravitational Θparameter
We describe the effect of the gravitational [Formula: see text]parameter on the behavior of the stretched horizon of a black hole in [Formula: see text]dimensions. The gravitational [Formula: see text]term is a total derivative, however, it affects the transport properties of the horizon. In particular, the horizon acquires a thirdorder parity violating, dimensionless transport coefficient which affects the way localized perturbations scramble on the horizon. In the context of the gauge/gravity duality, the [Formula: see text]term induces a nontrivial contact term in the energy–momentum tensor of a [Formula: see text]dimensional largeN gauge theory, which admits a dual gravity description. As a consequence, the dual gauge theory in the presence of the [Formula: see text]term acquires the same thirdorder parity violating transport coefficient.
more »
« less
 Award ID(s):
 1620610
 NSFPAR ID:
 10107114
 Date Published:
 Journal Name:
 International Journal of Modern Physics D
 Volume:
 25
 Issue:
 12
 ISSN:
 02182718
 Page Range / eLocation ID:
 1644022
 Format(s):
 Medium: X
 Sponsoring Org:
 National Science Foundation
More Like this


null (Ed.)This article discusses some of the history of parityviolation experiments that culminated in the Q weak experiment, which provided the first determination of the proton's weak charge [Formula: see text]. The guiding principles necessary to the success of that experiment are outlined, followed by a brief description of the Q weak experiment. Several consistent methods used to determine [Formula: see text] from the asymmetry measured in the Q weak experiment are explained in detail. The weak mixing angle sin 2 θ w determined from [Formula: see text] is compared with results from other experiments. A description of the procedure for using the [Formula: see text] result on the proton to set TeVscale limits for new parityviolating semileptonic physics beyond the Standard Model (BSM) is presented. By also considering atomic parityviolation results on cesium, the article shows how this result can be generalized to set limits on BSM physics, which couples to any combination of valence quark flavors. Finally, the discovery space available to future weakcharge measurements is explored.more » « less

In this paper, we extend the nonAbelian mirror proposal of two of the authors from twodimensional gauge theories with connected gauge groups to the case of [Formula: see text] gauge groups with discrete theta angles. We check our proposed extension by counting and comparing vacua in mirrors to the known dual twodimensional [Formula: see text] gauge theories. The mirrors in question are Landau–Ginzburg orbifolds, and for mirrors to [Formula: see text] gauge theories, the critical loci of the mirror superpotential often intersect fixedpoint loci, so that to count vacua, one must take into account the twisted sector contributions. This is a technical novelty relative to the mirrors of gauge theories with connected gauge groups, for which critical loci do not intersect fixedpoint loci and so no orbifold twisted sector contributions are pertinent. The vacuum computations turn out to be a rather intricate test of the proposed mirrors, in particular as untwisted sector states in the mirror to one theory are often exchanged with twisted sector states in the mirror to the dual. In cases with nontrivial IR limits, we also check that the central charges computed from the Landau–Ginzburg mirrors match those expected for the IR SCFTs.more » « less

A bstract We consider a holographic model of strongly interacting plasma with a gravitational anomaly. In this model, we compute parityodd responses of the system at finite temperature and chemical potential to external electromagnetic and gravitational fields. Working within the linearized fluid/gravity duality, we performed the calculation up to the third order in gradient expansion. Besides reproducing the chiral magnetic (CME) and vortical (CVE) effects we also obtain gradient corrections to the CME and CVE due to the gravitational anomaly. Additionally, we find energymomentum and current responses to the gravitational field similarly determined by the gravitational anomaly. The energymomentum response is the first purely gravitational transport effect that has been related to quantum anomalies in a holographic theory.more » « less

Using a result of Longo and Xu, we show that the anomaly arising from a cyclic permutation orbifold of order 3 of a holomorphic conformal net [Formula: see text] with central charge [Formula: see text] depends on the “gravitational anomaly” [Formula: see text]. In particular, the conjecture that holomorphic permutation orbifolds are nonanomalous and therefore a stronger conjecture of Müger about braided crossed [Formula: see text]categories arising from permutation orbifolds of completely rational conformal nets are wrong. More generally, we show that cyclic permutations of order [Formula: see text] are nonanomalous if and only if [Formula: see text] or [Formula: see text]. We also show that all cyclic permutation gaugings of [Formula: see text] arise from conformal nets.more » « less