International Journal of Modern Physics A

We review particle physics model building in type IIB string theory and F-theory. This is a region in the landscape where in principle many of the key ingredients required for a realistic model of particle physics can be combined successfully. We begin by reviewing moduli stabilization within this framework and its implications for supersymmetry breaking. We then review model building tools and developments in the weakly coupled type IIB limit, for both local D3-branes at singularities and global models of intersecting D7-branes. Much of recent model building work has been in the strongly coupled regime of F-theory due to the presence of exceptional symmetries which allow for the construction of phenomenologically appealing Grand Unified Theories. We review both local and global F-theory model building starting from the fundamental concepts and tools regarding how the gauge group, matter sector and operators arise, and ranging to detailed phenomenological properties explored in the literature.

In view of classification of the quiver 4d supersymmetric gauge theories, we discuss the characterization of the quivers with superpotential associated to a QFT which, in some corner of its parameter space, looks like a gauge theory with gauge group G. The basic idea is that the Abelian category of (finite-dimensional) representations of the Jacobian algebra should enjoy what we call the Ringel property of type G; in particular, should contain a universal "generic" subcategory, which depends only on the gauge group G, capturing the universality of the gauge sector. More precisely, there is a family of "light" subcategories , indexed by points λ ∈ N, where N is a projective variety whose irreducible components are copies of ℙ¹ in one-to-one correspondence with the simple factors of G. If λ is the generic point of the ith irreducible component, is the universal subcategory corresponding to the ith simple factor of G. Matter, on the contrary, is encoded in the subcategories where {λ_a} is a finite set of closed points in N.

In particular, for a Gaiotto theory there is one such family of subcategories, , for each maximal degeneration of the corresponding surface Σ, and the index variety N may be identified with the degenerate Gaiotto surface itself: generic light subcategories correspond to cylinders, while closed-point subcategories to "fixtures" (spheres with three punctures of various kinds) and higher-order generalizations. The rules for "gluing" categories are more general than the geometric gluing of surfaces, allowing for a few additional exceptional theories which are not of the Gaiotto class. We include several examples and some amusing consequence, as the characterization in terms of quiver combinatorics of asymptotically free theories.

Decoupling of a heavy flavor in QCD is discussed in a pedagogical way. First we consider a simpler case: decoupling of muons in QED. All calculations are done up to two loops.

In this work, we investigate the quantum theory of the Kalb–Ramond fields propagating in D-dimensional de Sitter space–times using the dynamic invariant method developed by Lewis and Riesenfeld [J. Math. Phys.10, 1458 (1969)] to obtain the solution of the time-dependent Schrödinger equation. The wave function is written in terms of a c-number quantity satisfying the Milne–Pinney equation, whose solution can be expressed in terms of two independent solutions of the respective equation of motion. We obtain the exact solution for the quantum Kalb–Ramond field in the de Sitter background and discuss its relation with the Cremmer–Scherk–Kalb–Ramond model.

In this paper, we will deform an ABJ theory in harmonic superspace without breaking any supersymmetry. We will analyze the ABJ theory and show that it retains the full supersymmetry. We will then analyze the gauge fixing and ghost terms for this model in various gauges. We will also analyze the corresponding BRST and anti-BRST symmetries of this model.

Symplectic unitary representations for the Galilei group are studied. The formalism is based on the noncommutative structure of the star-product, and using group theory approach as a guide, a consistent physical theory in phase space is constructed. The state of a quantum mechanics system is described by a quasi-probability amplitude that is in association with the Wigner function. As a result, the Schrödinger and Pauli–Schrödinger equations are derived in phase space. As an application, the Landau problem in phase space is studied. This shows how this method of quantum mechanics in phase space is to be brought to the realm of spatial noncommutative theories.

The CKM matrix describing quark mixing with three generations can be parametrized by three mixing angles and one CP-violating phase. In most of the parametrizations, the CP-violating phase chosen is not a directly measurable quantity and is parametrization dependent. In this work, we propose to use experimentally measurable CP-violating quantities, α, β or γ in the unitarity triangle as the phase in the CKM matrix, and construct explicit α, β and γ parametrizations. Approximate Wolfenstein-like expressions are also suggested. Since β is most accurately measured among these three phase angles, we consider β parametrization as the best one to use.