Particle theory

Abstract:

Compactifications of heterotic theories on smooth Calabi-Yau manifolds remain one of the most promising approaches to string phenomenology. In two previous papers, arXiv:1106.4804 and arXiv:1202.1757, large classes of such vacua were constructed, using sums of line bundles over complete intersection Calabi-Yau manifolds in products of projective spaces that admit smooth quotients by finite groups. A total of 1012 different vector bundles were investigated which led to 202 SU(5) Grand Unified Theory (GUT) models. With the addition of Wilson lines, these in turn led, by a conservative counting, to 2122 heterotic standard models. In the present paper, we extend the scope of this programme and perform an exhaustive scan over the same class of models. A total of 1040 vector bundles are analysed leading to 35, 000 SU(5) GUT models. All of these compactifications have the right field content to induce low-energy models with the matter spectrum of the supersymmetric standard model, with no exotics of any kind. The detailed analysis of the resulting vast number of heterotic standard models is a substantial and ongoing task in computational algebraic geometry. © 2014 SISSA.

Abstract:

We present our current results for the deconfining temperatures in SO(N) gauge theories in 2+1 dimensions. SO(2N) theories may help us to understand QCD at finite chemical potential since there is a large-N orbifold equivalence between SO(2N) QCD-like theories and SU(N) QCD, and SO(2N) theories do not have the sign problem present in QCD. We show that the deconfining temperatures in these two theories match at the large-N limit. We also present results for SO(2N +1) gauge theories and compare results for SO(6) with SU(4) gauge theories, which have the same Lie algebras but different centres.

Abstract:

We present an implementation of electroweak ZZjj production in the POWHEG BOX V2 framework, an upgrade of the POWHEG BOX program which includes a number of new features that are particularly helpful for high-multiplicity processes. We consider leptonic and semi-leptonic decay modes of the Z bosons, and take non-resonant contributions and spin correlations of the final-state particles into account. In the case of decays to leptons, we also include interactions beyond the Standard Model that arise from an effective Lagrangian which includes CP conserving and violating operators up to dimension six. We find that while leptonic distributions are very sensitive to anomalous couplings, because of the small cross-section involved, these analyses are feasible only after a high-luminosity upgrade of the LHC. We consider the cases of a 14 TeV, 33 TeV and 100 TeV machine and discuss the limits that can be placed on those couplings for different luminosities. Open Access, © The Authors. Article funded by SCOAP3.