10,272 research outputs found
Efficient structural symmetry breaking for constraint satisfaction problems
Symmetry breaking for constraint satisfaction
problems (CSPs) has attracted considerable attention
in recent years. Various general schemes have been proposed to eliminate symmetries. In general, these schemes may take exponential space or time to eliminate all the symmetries. We identify several classes of CSPs that encompass many practical problems and for which symmetry breaking for various forms of value and variable interchangeability is tractable using dedicated search procedures or symmetry-breaking constraints that allow nogoods and their symmetrically equivalent solutions to be stored and checked efficiently
Strong CP problem, axions, and cosmological implications of CP violation
In this talk, I present a pedagogical and historical review related to the CP
symmetry. It includes the weak CP violation, the strong CP problem, "invisible"
axions and cosmology, and Type-II leptogenesis.Comment: 21 pages of LaTeX file with 12 figures. Talk presented at Corfu,
Greec
Partially Supersymmetric Composite Higgs Models
We study the idea of the Higgs as a pseudo-Goldstone boson within the
framework of partial supersymmetry in Randall-Sundrum scenarios and their CFT
duals. The Higgs and third generation of the MSSM are composites arising from a
strongly coupled supersymmetric CFT with global symmetry SO(5) spontaneously
broken to SO(4), whilst the light generations and gauge fields are elementary
degrees of freedom whose couplings to the strong sector explicitly break the
global symmetry as well as supersymmetry. The presence of supersymmetry in the
strong sector may allow the compositeness scale to be raised to ~10 TeV without
fine tuning, consistent with the bounds from precision electro-weak
measurements and flavour physics. The supersymmetric flavour problem is also
solved. At low energies, this scenario reduces to the "More Minimal
Supersymmetric Standard Model" where only stops, Higgsinos and gauginos are
light and within reach of the LHC.Comment: 28 pages. v2 minor changes and Refs. adde
The Dispirited Case of Gauged Dark Matter
We explore the constraints and phenomenology of possibly the simplest
scenario that could account at the same time for the active neutrino masses and
the dark matter in the Universe within a gauged symmetry, namely
right-handed neutrino dark matter. We find that null searches from lepton and
hadron colliders require dark matter with a mass below 900 GeV to annihilate
through a resonance. Additionally, the very strong constraints from high-energy
dilepton searches fully exclude the model for . We further explore the phenomenology in the high mass region
(i.e. masses ) and highlight theoretical
arguments, related to the appearance of a Landau pole or an instability of the
scalar potential, disfavoring large portions of this parameter space.
Collectively, these considerations illustrate that a minimal extension of the
Standard Model via a local symmetry with a viable thermal dark
matter candidate is difficult to achieve without fine-tuning. We conclude by
discussing possible extensions of the model that relieve tension with collider
constraints by reducing the gauge coupling required to produce the correct
relic abundance.Comment: 21 pages, 8 figures. v2: References added. Matches the published
versio
Open boundary Quantum Knizhnik-Zamolodchikov equation and the weighted enumeration of Plane Partitions with symmetries
We propose new conjectures relating sum rules for the polynomial solution of
the qKZ equation with open (reflecting) boundaries as a function of the quantum
parameter and the -enumeration of Plane Partitions with specific
symmetries, with . We also find a conjectural relation \`a la
Razumov-Stroganov between the limit of the qKZ solution and refined
numbers of Totally Symmetric Self Complementary Plane Partitions.Comment: 27 pages, uses lanlmac, epsf and hyperbasics, minor revision
Space group symmetry fractionalization in a chiral kagome Heisenberg antiferromagnet
The anyonic excitations of a spin-liquid can feature fractional quantum
numbers under space-group symmetries. Detecting these fractional quantum
numbers, which are analogs of the fractional charge of Laughlin quasiparticles,
may prove easier than the direct observation of anyonic braiding and
statistics. Motivated by the recent numerical discovery of spin-liquid phases
in the kagome Heisenberg antiferromagnet, we theoretically predict the pattern
of space group symmetry fractionalization in the kagome lattice chiral spin
liquid. We provide a method to detect these fractional quantum numbers in
finite-size numerics which is simple to implement in DMRG. Applying these
developments to the chiral spin liquid phase of a kagome Heisenberg model, we
find perfect agreement between our theoretical prediction and numerical
observations.Comment: 5 pages plus appendi
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