58 research outputs found
Product Group S-Confinement in SUSY Gauge Theories
We propose a new set of s-confining theories with product gauge groups and no
tree-level superpotential, based on a model with one antisymmetric matter field
and four flavors of quarks. For each product group we find a set of
gauge-invariant operators which satisfy the 't Hooft anomaly matching
conditions, and we identify the dynamically generated superpotential which
reproduces the classical constraints between operators. Several of these
product gauge theories confine without breaking chiral symmetry, even in cases
where the classical moduli space is quantum-modified. These results may be
useful for composite model building, particularly in cases where small meson
operators are absent, or for theories with multiple natural energy scales, and
may provide new ways to break supersymmetry dynamically.Comment: 28 pages, 8 tables, one appendi
A High Quality Composite Axion
The strong CP problem is a compelling motivation for physics beyond the
Standard Model. The most popular solutions invoke a global Peccei-Quinn
symmetry, but are challenged by quantum gravitational corrections which are
thought to be incompatible with global symmetries, arguing that realistic
theories contain additional structure. We explore a construction in which the
Peccei-Quinn symmetry is protected to arbitrary order by virtue of a
supersymmetric, confining
product gauge group, achieving for an model
with GeV. This construction leads to low energy
predictions such as a gauge symmetry, and for engineers a
naturally order ~TeV value for the parameter of the MSSM.Comment: 17 pages, 2 figures, 3 table
Kaluza-Klein gluons at 100 TeV: NLO corrections
We explore the reach of a 100 TeV proton collider to discover KK gluons in a
warped extra dimension. These particles are templates for color adjoint vectors
that couple dominantly to the top quark. We examine their production rate at
NLO in the six-flavor m-ACOT scheme for a variety of reference models defining
their coupling to quarks, largely inspired by the RS model of a warped extra
dimension. In agreement with previous calculations aimed at lower energy
machines, we find that the NLO corrections are typically negative, resulting in
a -factor of around 0.7 (depending on the model) and with a residual scale
dependence on the order of , greater than the variation from the
scale exhibited by the na\"{i}ve LO estimate.Comment: 33 pages, 5 figures, 2 table
The Flavor of Cosmology
We discuss the cosmology of models in which the standard model Yukawa
couplings depend on scalar field(s), often referred to as flavons. We find that
thermal corrections of the flavon potential tend to decrease the Yukawa
couplings, providing an important input to model-building. Working in the
specific framework of Froggatt-Nielsen models, we compute the abundance of
flavons in the early universe generated both via freeze-in and from coherent
oscillations induced by thermal corrections to their potential, and discuss
constraints on flavon models from cosmology. We find that cosmology places
important constraints on theories containing flavons even for regions of
parameter space inaccessible to collider searches.Comment: 26 pages, 5 figures, 5 appendice
Neutralizing Topological Obstructions to Bubbles of Nothing
Theories with compact extra dimensions can exhibit a vacuum instability known
as a bubble of nothing. These decay modes can be obstructed if the internal
manifold is stabilized by fluxes, or if it carries Wilson lines for background
gauge fields, or if the instanton is incompatible with the spin structure. In
each of these cases the decay can proceed by adding dynamical charged membranes
or gauge fields. We give a general, bottom-up procedure for constructing
approximate bubble of nothing solutions in models with internal spheres
stabilized by flux and study the influence of the brane tension on the
tunneling exponent, finding two branches of solutions that merge at a minimal
superextremal value of the tension. In the case of Wilson operators and
incompatible fermions, the relevant bubble is shown to be the Euclidean
Reissner-Nordstrom black hole, and the ordinary decay exponent is modified by
effects. We examine the Dirac operator on this background and comment
on the relevance for models of supergravity with gauged -symmetry.Comment: 29 pages, 9 figure
The Molecular Migdal Effect
Nuclear scattering events with large momentum transfer in atomic, molecular,
or solid-state systems may result in electronic excitations. In the context of
atomic scattering by dark matter (DM), this is known as the Migdal effect, but
the same effect has also been studied in molecules in the chemistry and neutron
scattering literature. Here we present two distinct Migdal-like effects from DM
scattering in molecules, which we collectively refer to as the molecular Migdal
effect: a center-of-mass recoil, equivalent to the standard Migdal treatment,
and a non-adiabatic coupling resulting from corrections to the Born-Oppenheimer
approximation. The molecular bonds break spherical symmetry, leading to large
daily modulation in the Migdal rate from anisotropies in the matrix elements.
Our treatment reduces to the standard Migdal effect in atomic systems but does
not rely on the impulse approximation or any semiclassical treatments of
nuclear motion, and as such may be extended to models where DM scatters through
a long-range force. We demonstrate all of these features in a few simple toy
models of diatomic molecules, namely , N, and CO, and find
total molecular Migdal rates competitive with those in semiconductors for the
same target mass. We discuss how our results may be extended to more realistic
targets comprised of larger molecules which could be deployed at the kilogram
scale.Comment: v1: 15+2 pages, 7 figure
Experimental Investigation of Project Orion Crew Exploration Vehicle Aeroheating in AEDC Tunnel 9
An investigation of the aeroheating environment of the Project Orion Crew Entry Vehicle has been performed in the Arnold Engineering Development Center Tunnel 9. The goals of this test were to measure turbulent heating augmentation levels on the heat shield and to obtain high-fidelity heating data for assessment of computational fluid dynamics methods. Laminar and turbulent predictions were generated for all wind tunnel test conditions and comparisons were performed with the data for the purpose of helping to define uncertainty margins for the computational method. Data from both the wind tunnel test and the computational study are presented herein
A composite axion from a supersymmetric product group
A global symmetry is protected from gravitational effects in
the s-confining product group theory with
matter. If the family symmetry is gauged and an appropriate tree-level
superpotential is added, then the dynamically generated superpotential
spontaneously breaks and
produces a QCD axion. Small values of the -violating parameter are
then possible without any fine-tuning, as long as the product group is suitably
large. By introducing a second copy of the s-confining product group
also coupled to the gauged , we find that values as small as are
consistent with , even under the pessimistic assumption
that the dominant contribution to the axion quality is at tree level.Comment: 16 pages, 3 figures, 4 tables, 2 appendice
- …