Phase Diagram of the Two-Flavor Schwinger Model at Zero Temperature.

We examine the phase structure of the two-flavor Schwinger model as a function of the θ angle and the two masses, m_{1} and m_{2}. In particular, we find interesting effects at θ=π: along the SU(2)-invariant line m_{1}=m_{2}=m, in the regime where m is much smaller than the charge g, the theory undergoes logarithmic renormalization group flow of the Berezinskii-Kosterlitz-Thouless type. As a result, dimensional transmutation takes place, leading to a nonperturbatively small mass gap ∼e^{-Ag^{2}/m^{2}}. The SU(2)-invariant line lies within a region of the phase diagram where the charge conjugation symmetry is spontaneously broken and whose boundaries we determine numerically. Our numerical results are obtained using the Hamiltonian lattice gauge formulation that includes the mass shift m_{lat}=m-g^{2}a/4 dictated by the discrete chiral symmetry.

The Link between Activities of Hepatic 11beta-Hydroxysteroid Dehydrogenase-1 and Monoamine Oxidase-A in the Brain Following Repeated Predator Stress: Focus on Heightened Anxiety.

We investigated the presence of a molecular pathway from hepatic 11-ßHSD-1 to brain MAO-A in the dynamics of plasma corticosterone involvement in anxiety development. During 14 days following repeated exposure of rats to predator scent stress for 10 days, the following variables were measured: hepatic 11-ßHSD-1 and brain MAO-A activities, brain norepinephrine, plasma corticosterone concentrations, and anxiety, as reflected by performance on an elevated plus maze. Anxiety briefly decreased and then increased after stress exposure. This behavioral response correlated inversely with plasma corticosterone and with brain MAO-A activity. A mathematical model described the dynamics of the biochemical variables and predicted the factor(s) responsible for the development and dynamics of anxiety. In the model, hepatic 11-ßHSD-1 was considered a key factor in defining the dynamics of plasma corticosterone. In turn, plasma corticosterone and oxidation of brain ketodienes and conjugated trienes determined the dynamics of brain MAO-A activity, and MAO-A activity determined the dynamics of brain norepinephrine. Finally, plasma corticosterone was modeled as the determinant of anxiety. Solution of the model equations demonstrated that plasma corticosterone is mainly determined by the activity of hepatic 11-ßHSD-1 and, most importantly, that corticosterone plays a critical role in the dynamics of anxiety following repeated stress.

Critical Field Theories with OSp(1|2M) Symmetry.

In the paper [L. Fei et al., J. High Energy Phys. 09 (2015) 076JHEPFG1029-847910.1007/JHEP09(2015)076] a cubic field theory of a scalar field σ and two anticommuting scalar fields, θ and θ[over ¯], was formulated. In 6-ε dimensions it has a weakly coupled fixed point with imaginary cubic couplings where the symmetry is enhanced to the supergroup OSp(1|2). This theory may be viewed as a "UV completion" in 2

Spectrum of Majorana Quantum Mechanics with O(4)

We study the quantum mechanics of three-index Majorana fermions ψ^{abc} governed by a quartic Hamiltonian with O(N)^{3} symmetry. Similarly to the Sachdev-Ye-Kitaev model, this tensor model has a solvable large-N limit dominated by the melonic diagrams. For N=4 the total number of states is 2^{32}, but they naturally break up into distinct sectors according to the charges under the U(1)×U(1) Cartan subgroup of one of the O(4) groups. The biggest sector has vanishing charges and contains over 165 million states. Using a Lanczos algorithm, we determine the spectrum of the low-lying states in this and other sectors. We find that the absolute ground state is nondegenerate. If the SO(4)^{3} symmetry is gauged, it is known from earlier work that the model has 36 states and a residual discrete symmetry. We study the discrete symmetry group in detail; it gives rise to degeneracies of some of the gauge singlet energies. We find all the gauge singlet energies numerically and use the results to propose exact analytic expressions for them.

Effects of compactification in D-brane inflation.

In D3-brane inflation, the inflaton potential receives important contributions from sources in the compact space, such as fluxes, other D-branes, and orientifold planes. Most previous analyses have considered only the effects of sources near to the inflationary D3-brane, but in fact distant sources do not generically decouple and can critically influence the dynamics during inflation. We provide a systematic method for incorporating the effects of arbitrary distant sources as perturbations to the local supergravity background. We use this approach to obtain the structure of the potential for a D3-brane in a warped throat geometry attached to a general compact space. A significant, and well-known, contribution to this potential arises from quantum effects involved in the stabilization of the compactification volume. Our method automatically captures these effects, encoding them in a suitable flux background.

A delicate universe: compactification obstacles to D-brane inflation.

We investigate whether explicit models of warped D-brane inflation are possible in string compactifications. To this end, we study the potential for D3-brane motion in a warped conifold that includes holomorphically embedded D7-branes involved in moduli stabilization. The presence of the D7-branes significantly modifies the inflaton potential. We construct an example based on a very simple and symmetric embedding due to Kuperstein, z1= const, in which it is possible to fine-tune the potential so that slow-roll inflation can occur. The resulting model is rather delicate: inflation occurs in the vicinity of an inflection point, and the cosmological predictions are extremely sensitive to the precise shape of the potential.