Akin Wingerter

A Mini-landscape of exact MSSM spectra in heterotic orbifolds

We explore a “fertile patch” of the heterotic landscape based on a 6-II orbifold with SO(10) and E6 local GUT structures. We search for models allowing for the exact MSSM spectrum. Our result is that of order 100 out of a total 3 × 10 4 inequivalent models satisfy this requirement.

Tribimaximal mixing from small groups

Current experimental data on the neutrino parameters is in good agreement with tribimaximal mixing and may indicate the presence of an underlying family symmetry. For 76 flavor groups, we perform a systematic scan for models: The particle content is that of the Standard Model plus up to three flavon fields, and the effective Lagrangian contains all terms of mass dimension <=6. We find that 44 groups can accommodate models that are consistent with experiment at 3 sigma, and 38 groups can have models that are tribimaximal. For one particular group, we look at correlations between the mixing angles and make a prediction for theta13 that will be testable in the near future. We present the details of a model with theta12=33.9, theta23=40.9, theta13=5.1 to show that the recent tentative hints of a non-zero theta13 can easily be accommodated. The smallest group for which we find tribimaximal mixing is T7. We argue that T7 and T13 are as suited to produce tribimaximal mixing as A4 and should therefore be considered on equal footing. In the appendices, we present some new mathematical methods and results that may prove useful for future model building efforts.

Low energy supersymmetry from the heterotic string landscape

We study possible correlations between properties of the observable and hidden sectors in heterotic string theory. Specifically, we analyze the case of the Z6-II orbifold compactification which produces a significant number of models with the spectrum of the supersymmetric standard model. We find that requiring realistic features does affect the hidden sector such that hidden sector gauge group factors SU(4) and SO(8) are favored. In the context of gaugino condensation, this implies low energy supersymmetry breaking.

Exploring the SO(32) heterotic string

We give a complete classification of N orbifold compactification of the heterotic SO(32) string theory and show its potential for realistic model building. The appearance of spinor representations of SO(2n) groups is analyzed in detail. We conclude that the heterotic SO(32) string constitutes an interesting part of the string landscape both in view of model constructions and the question of heterotic-type I duality.

Geometry of rank reduction

We show how one can obtain geometric scaling properties from the Balitsky-Kovchegov (BK) equation. We start by explaining how, this property arises for the b-independent BK equation. We show that it is possible to extend this model to the full BK equation including momentum transfer. The saturation scale behaves like max(q, QT) where q is the momentum transfer and QT a typical scale of the target. Geometric scaling 1 expresses the fact that the DIS HERA data depend of the virtuality Q 2 and the rapidity Y = log(1/x) only through the ratio Q/Q s (Y) where Q s is an energy-dependent scale. On another side, a lot of research have been done during the last ten years to obtain a description of the saturation effects in the high-energy limit of QCD, leading to the Balitsky-Kovchegov equation 2. This equation supplements the BFKL 3 equation in including the contributions from fan diagrams. It has recently been shown in the framework of the impact-parameter independent BK equation that one can infer geometric scaling from the asymptotic solutions of the evolution equation. We shall explain how we have extended these properties of geometric scaling to the case of the full BK equation. Our analysis is performed in momentum space where we also introduce a new form of the BK equation. We shall discuss the properties of the saturation scale and its momentum-transfer dependence. Let us thus start our analysis by considering the case of the impact-parameter independent BK equation: N (x, y) = N (|x−y|). If we go to momentum space using ˜ N (k) = 1 2π d 2 r r 2 e ik.r N (r) = ∞ 0 dr r J 0 (kr)N (r), a On leave from the fundamental theoretical physics group of the University ofLì ege.We introduce continuous Wilson lines to reduce the rank of the gauge group in orbifold constructions. In situations where the orbifold twist can be realized as a rotation in the root lattice of a grand unified group we derive an appealing geometric picture of the symmetry breakdown. This symmetry breakdown is smooth and corresponds to a standard field theory Higgs mechanism. The embedding into heterotic string theory is discussed.

Yukawa unification predictions for the LHC

This paper is divided into two parts. In the first part we analyze the consequences, for the LHC, of gauge and third family Yukawa coupling unification with a particular set of boundary conditions defined at the GUT scale. We perform a global chi^2 analysis including the observables M_W, M_Z, G_F, 1/alpha_em, alpha_s(M_Z), M_t,m_b(m_b), M_tau, BR(B -> X_s gamma), BR(B_s -> mu^+ mu^-) and M_h. The fit is performed in the MSSM in terms of 9 GUT scale parameters, while tan beta and mu are fixed at the weak scale. Good fits suggest an upper bound on the gluino mass, M_gluino \lesssim 2 TeV. This constraint comes predominantly from fitting the bottom quark and Higgs masses (assuming a 125 GeV Higgs). Gluinos should be visible at the LHC in the 14 TeV run but they cannot be described by the typical simplified models. This is because the branching ratios for gluino -> t tbar neutralino, b bbar neutralino, t bbar chargino^-, b tbar chargino^+, g neutralino are comparable. Stops and sbottoms may also be visible. Charginos and neutralinos can be light with the LSP predominantly bino-like. In the second part of the paper we analyze a complete three family model and discuss the quality of the global chi^2 fits and the differences between the third family analysis and the full three family analysis for overlapping observables. We note that the light Higgs in our model couples to matter like the Standard Model Higgs. Any deviation from this would rule out this model.

Reconciling Grand Unification with Strings by Anisotropic Compactifications

We analyze gauge coupling unification in the context of heterotic strings on anisotropic orbifolds. This construction is very much analogous to effective five-dimensional orbifold grand unified theory field theories. Our analysis assumes three fundamental scales: the string scale

Higgs mechanism in heterotic orbifolds

{M}_{\mathrm{S}}

Gauge Coupling Unification and Light Exotica in String Theory

, a compactification scale

A Scan for Models of Neutrino Mixing from Non-Abelian Discrete Symmetries

{M}_{\mathrm{C}}