Shinji Hirano

D3 / D7 inflationary model and M theory

A proposal is made for a cosmological D3-D7 model with a constant magnetic flux along the D7 world volume. It describes an

String theory and hybrid inflation / acceleration

mathcal{N}=2

Summing up all genus free energy of ABJM matrix model

gauge model with Fayet-Iliopoulos terms and the potential of the hybrid P-term inflation. The motion of the D3-brane towards D7 in a phase with spontaneously broken supersymmetry provides a period of slow-roll inflation in the de Sitter valley, the role of the inflaton being played by the distance between D3- and D7-branes. After tachyon condensation a supersymmetric ground state is formed: a D3-D7 bound state corresponding to an Abelian non-linear (non-commutative) instanton. In this model the existence of a non-vanishing cosmological constant is associated with the resolution of the instanton singularity. We discuss a possible embedding of this model into a compactified M-theory setup.

The partition function of ABJ theory

We find a description of hybrid inflation in (3+1)-dimensions using brane dynamics of Hanany-Witten type. P-term inflation/acceleration of the universe with the hybrid potential has a slow-roll de Sitter stage and a waterfall stage which leads towards an = 2 supersymmetric ground state. We identify the slow-roll stage of inflation with a non-supersymmetric `Coulomb phase with Fayet-Iliopoulos term. This stage ends when the mass squared of one of the scalars in the hypermultiplet becomes negative. At that moment the brane system starts undergoing a phase transition via tachyon condensation to a fully Higgsed supersymmetric vacuum which is the absolute ground state of P-term inflation. A string theory/cosmology dictionary is provided, which leads to constraints on parameters of the brane construction from cosmological experiments. We display a splitting of mass levels reminiscent of the Zeeman effect due to spontaneous supersymmetry breaking.

Degradation mechanism of zinc oxide varistors under dc bias

The localization technique allows us to compute the free energy of the U(N)ku2009×u2009U(N)−k Chern-Simons-matter theory dual to type IIA strings on AdS4u2009×u2009CP3 from weak to strong ’t Hooft coupling λu2009=u2009N/k at finite N, as demonstrated by Drukker, Mariño, and Putrov. In this note we study further the free energy at large ’t Hooft coupling with the aim of testing AdS/CFT at the quantum gravity level and, in particular, sum up allthe1/N corrections, apart from the worldsheet instanton contributions. The all genus partition function takes a remarkably simple form — the Airy function,

Branes ending on branes in a tachyon model

{text{Ai}}left( {{{left( {{{{pi {k^2}}} left/ {{sqrt {2} }} right.}} right)}^{{{2} left/ {3} right.}}}{lambda_{text{ren}}}} right)

Observations on open and closed string scattering amplitudes at high energies

, with the renormalized ’t Hooft coupling λren.

Metamorphosis of tachyon profile in unstable D9-branes

This article has been accepted for publication in . Prog. Theor. Exp. Phys. (2013) 053B04 ndoi: 10.1093/ptep/ptt014. Published by Oxford University Press.

Giant gravitons on AdS4 × \mathbb{C} P3 and their holographic three-point functions

The degradation mechanism of ZnO varistors under dc bias is investigated from the viewpoint of the time dependence of leakage current under dc biasing, the voltage‐current characteristics, and the thermally stimulated current and dielectric properties before and after dc biasing test. The experimental results are analyzed on the basis of the Schottky barriers which control current transport in varistors at the grain boundary regions. The increase in leakage current is expressed as J = Au2009exp (Bt0.3) (u2009J is the leakage current; A and B are constants, and t the biasing time) and is attributed to the deformation of the Schottky barriers. The deformation corresponds to the lowering of the barrier height and decrease in the depletion width. This is due to the uneven distribution of positive charges caused by the migration of donor ions. In case of the degradation of varistors under long term dc bias, the deformation is mainly due to decrease in the depletion width. Taking into account the electric field due to ...

ABJ theory in the higher spin limit

In a tachyon model proposed by Minahan and Zwiebach and derived in the boundary string field theory, we construct various new solutions which correspond to nontrivial brane configurations in string theory. Our solutions include Dp-D(p−2) bound states, (F, Dp) bound states, string junctions, D(p−2)-branes ending on a Dp-brane, D(p−2)-branes suspended between parallel Dp-branes and their non-commutative generalizations. We find the Bogomolnyi bounds and the BPS equations for some of our solutions, and check the physical consistency of our solutions with the D-brane picture by looking at the distributions of their energies and RR-charges in space. We also give conjectures for a few other brane configurations.