5,860 research outputs found
Natural Fermion Hierarchies from Random Yukawa Couplings
The Standard Model of particle physics requires Yukawa matrices with
eigenval- ues that differ by orders of magnitude. We propose a novel way to
explain this fact without any small or large parameters. The mechanism is based
on the observation that products of matrices of random order one-numbers have
hierarchical spectra. The same mechanism can easily account for the
hierarchical structure of the quark mixing matrix.Comment: 9 pages. v2: Extended and improved discussion on CKM matrix.
References added. Matches published versio
Realistic GUT Yukawa Couplings from a Random Clockwork Model
We present realistic models of flavor in SU(5) and SO(10) grand unified
theories (GUTs). The models are renormalizable and do not require any exotic
representations in order to accommodate the necessary GUT breaking effects in
the Yukawa couplings. They are based on a simple clockwork Lagrangian whose
structure is enforced with just two (one) vectorlike U(1) symmetries in the
case of SU(5) and SO(10) respectively. The inter-generational hierarchies arise
spontaneously from products of matrices with order one random entries.Comment: 18 pages, 2 figure
One-Loop Effective Action in Orbifold Compactifications
We employ the covariant background formalism to derive generic expressions
for the one-loop effective action in field theoretic orbifold
compactifications. The contribution of each orbifold sector is given by the
effective action of its fixed torus with a shifted mass matrix. We thus study
in detail the computation of the heat kernel on tori. Our formalism manifestly
separates UV sensitive (local) from UV-insensitive (nonlocal) renormalization.
To exemplify our methods, we study the effective potential of 6d gauge theory
as well as kinetic terms for gravitational moduli in 11d supergravity.Comment: 30 pages, 1 figure, 3 tables, v2: appendix on zeta function
regularization added, discussion of 6d example expanded, version to appear in
JHE
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