Bulk entanglement and its shape dependence

We study bulk entanglement entropy in even spacetime dimensions using the heat kernel method, which captures the universal piece of entanglement entropy, a logarithmically divergent term in even dimensions. In four dimensions, we perform explicit calculations for various shapes of boundary subregions. In particular, for a cusp subregion with an arbitrary opening angle, we find that the bulk entanglement entropy always encodes the same universal information about the boundary theories as the leading entanglement entropy in the large N limit, up to a fixed proportional constant. By smoothly deforming a circle in the boundary, we find that to leading order of the deformations, the bulk entanglement entropy shares the same shape dependence as the leading entanglement entropy and hence the same physical information can be extracted from both cases. This establishes an interesting local/nonlocal relation for holographic $$\mathrm {CFT}_3$$ CFT 3 . However, the result does not hold for higher dimensional holographic theories.

On the Higgs mass fine-tuning problem with multi-Higgs doublet models

With no conclusive signal till date of the minimal supersymmetric and extra-dimensional models at the Large Hadron Collider (LHC), the issue of naturalness of the Higgs mass still calls for attention. One way to achieve that is to introduce additional bosonic degrees of freedom and rely on fine-tuning thereafter. That is, to arrange for a cancellation between various parameters so that the coefficient of the quadratically divergent term in the Higgs mass is vanishing or small to a manageable level. In this work, we explore the possibility of doing so using two- and three-Higgs doublet models. We consider different versions of the same and fold in various relevant constraints accordingly. The study reveals that the quadratically divergent mass term of the 125 GeV Higgs can be exactly canceled in most of the models considered here. However, the same does not hold for the nonstandard scalars owing to the applied constraints.

PHOTON-NEUTRINO INTERACTION IN θ-EXACT COVARIANT MODEL: PHENOMENOLOGY AND QUANTUM PROPERTIES

We construct the theta-exact covariant noncommutative model and obtain various closed constraints on the noncommutative scale from inelastic neutrino-nucleon scatterings, from plasmon decay into neutrino pair, from the Big Bang Nucleosynthesis and from the reheating phase after inflation, respectively. We find neutrino two-point function in a closed form and decoupling of the UV divergent term from softened UV/IR mixing term. Deformed dispersion relations at low energies are capable to account for the recent results from the OPERA collaboration on the superluminal speed of the muon neutrinos.

TWO-FORM GRAVITY AND THE GENERATION OF SPACE-TIME

In the framework of the two-form gravity, which is classically equivalent to the Einstein gravity, the one-loop effective potential for the conformal factor of metric is calculated in the finite volume and in the finite temperature by choosing a temporal gauge condition. There appears a quartically divergent term which cannot be removed by the renormalization of the cosmological term and we find there is only one nontrivial minimum in the effective potential. If the cutoff scale has a physical meaning, e.g. the Planck scale coming from string theory, this minimum might explain why the space-time is generated, i.e. why the classical metric has a nontrivial value.

ONE-LOOP STRING CORRECTIONS TO GAUGE CHARGE

We derive explicit formulae in terms of ϑ-functions for calculating the one-loop string corrections to the low-energy gauge group charges of the Z3 orbifold. An operator-expansion motivated regularization scheme, which resolves the “0/0” ambiguity arising in such calculations, is proposed and analyzed. An appearance of a special “quadratic-divergent” term, not predicted by a naive field-theoretic analysis, is discussed. Finally we numerically estimate the influence of the massive string states on the renormalization group calculations of the gauge charge.