Angelantonj, Carlo Partouche, Hervé Pradisi, Gianfranco

The moduli space of toroidal type I vacua, which are consistent at the non-perturbative level, is composed of independent branches characterized by the number (0, 16 or 32) of rigid branes sitting on top of orientifold planes. This structure persists also when supersymmetry is spontaneously broken à la Scherk–Schwarz. We show that all the component...

Partouche, Hervé de Vaulchier, Balthazar

When supersymmetry is spontaneously broken at tree level, the spectrum of the heterotic string compactified on orbifolds of tori contains an infinite number of potentially tachyonic modes. We show that this implies instabilities of Minkowski spacetime, when the scale of supersymmetry breaking is of the order of the string scale. We derive the phase...

Kehagias, Alexandros Partouche, Herve

We discuss the Casimir effect in heterotic string theory. This is done by considering a Z_2 twist acting on one external compact direction and three internal coordinates. The hyperplanes fixed by the orbifold generator G realize the two infinite parallel plates. For the latter to behave as "conducting material", we implement in a modular invariant ...

Matsumoto, Shigeki Shirai, Satoshi Takeuchi, Michihisa
Published in
Journal of High Energy Physics

Electroweak-interacting massive particles (EWIMPs) exist in a broad class of new physics models beyond the Standard Model. Searching for such particles is one of most primary goal at the LHC and future colliders. The EWIMP generally affects the LHC signatures through quantum corrections even without direct productions. By measuring the Standard Mod...

Addazi, Andrea Ketov, Sergei V. Khlopov, Maxim Yu.
Published in
The European Physical Journal C

We study production of gravitino and Polonyi particles in the minimal Starobinsky-Polonyi N=1\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\mathcal {N}=1$$\end{docume...

Coudarchet, Thibaut Partouche, Herve

We analyze quantum no-scale regimes (QNSR) in perturbative heterotic string compactified on tori, with total spontaneous breaking of supersymmetry. We show that for marginal deformations initially at any point in moduli space, the dynamics of a flat, homogeneous and isotropic universe can always be attracted to a QNSR. This happens independently of...

Florakis, Ioannis

We review recent progress in addressing the decompactification problem of gauge couplings in the context of heterotic string theory with spontaneous supersymmetry breaking. This problem is particularly relevant in large volume scenarios where quantum corrections to gauge couplings typically explode and the theory is driven to the non-perturbative r...

Coudarchet, Thibaut Fleming, Claude Partouche, Herve

We show that in generic no-scale models in string theory, the flat, expanding cosmological evolutions found at the quantum level can be attracted to a "quantum no-scale regime", where the no-scale structure is restored asymptotically. In this regime, the quantum effective potential is dominated by the classical kinetic energies of the no-scale modu...

Bellazzini, Brando
Published in
Journal of High Energy Physics

We derive positivity bounds for scattering amplitudes of particles with arbitrary spin using unitarity, analyticity and crossing symmetry. The bounds imply the positivity of certain low-energy coefficients of the effective action that controls the dynamics of the light degrees of freedom. We show that low-energy amplitudes strictly softer than O(p4...