2,982 research outputs found
String Inspired Singlet Extensions of the Minimal Supersymmetric Standard Model
The only allowed Higgs superpotential term at stringy tree level in the
string derived Singlet Extensions of the Minimal Supersymmetric Standard Model
(SEMSSM) is h S H_d H_u, which leads to an additional global U(1) symmetry in
the Higgs potential. We propose the string inspired SEMSSM where the global
U(1) symmetry is broken by the additional superpotential terms or supersymmetry
breaking soft terms that can be obtained naturally due to the instanton effects
or anomalous U(1)_A gauge symmetry. In these models, we can solve the \mu
problem and the fine-tuning problem for the lightest CP-even Higgs boson mass
in the MSSM, generate the baryon asymmetry via electroweak baryogenesis, and
predict the new Higgs physics which can be tested at the LHC and ILC.Comment: RevTex4, 5 pages, 2 tables, comments and references added, version to
appear in PL
Target-Space Duality in Heterotic and Type I Effective Lagrangians
We study the implications of target-space duality symmetries for low-energy
effective actions of various four-dimensional string theories. In the heterotic
case such symmetries can be incorporated in simple orbifold examples. At
present a similar statement cannot be made about the simplest type IIB
orientifolds due to an obstruction at the level of gravitational anomalies.
This fact confirms previous doubts concerning a conjectured heterotic-type IIB
orientifold duality and shows that target-space symmetries can be a powerful
tool in studying relations between various string theories at the level of the
effective low-energy action. Contraints on effective Lagrangians from these
symmetries are discussed in detail. In particular, we consider ways of
extending T-duality to include additional corrections to the Kaehler potential
in heterotic string models with N=2 subsectors.Comment: 30 pages, LaTeX2
Hybrid-bias and displacement emulators for field-level modelling of galaxy clustering in real and redshift space
Recently, hybrid bias expansions have emerged as a powerful approach to
modelling the way in which galaxies are distributed in the Universe. Similarly,
field-level emulators have recently become possible thanks to advances in
machine learning and -body simulations. In this paper we explore whether
both techniques can be combined to provide a field-level model for the
clustering of galaxies in real and redshift space. Specifically, here we will
demonstrate that field-level emulators are able to accurately predict all the
operators of a -order hybrid bias expansion. The precision achieved
in real and redshift space is similar to that obtained for the nonlinear matter
power spectrum. This translates to roughly 1-2\% precision for the power
spectrum of a BOSS and a Euclid-like galaxy sample up to Mpc.
Remarkably, this combined approach also delivers precise predictions for
field-level galaxy statistics. Despite all these promising results, we detect
several areas where further improvements are required. Therefore, this work
serves as a road-map for the developments required for a more complete
exploitation of upcoming large-scale structure surveys.Comment: 13 pages, 9 figure
Scales of Gaugino Condensation and Supersymmetry Breaking in Nonstandard M-Theory Embeddings
We investigate the formation of dynamical gaugino condensates and
supersymmetry breaking in the compactifications of Horava-Witten theory with
perturbative nonstandard embeddings. Specific models are considered where the
underlying massless charged states of the condensing sector are determined by
the spectra of and orbifolds with nonstandard
embeddings. We find among them viable examples where gaugino condensation is
triggered on the wall with the weakest gauge coupling at . In all
these cases the magnitude of the condensate formed is below the energy scales
at which extra dimensions are resolved, and so justifies the analysis of
condensation in an effective 4-dimensional framework. We make some comments
concerning the size of the largest extra dimension in the models considered. We
discuss racetrack scenarios in the framework of perturbative nonstandard
embeddings.Comment: 28 pages, 7 figures, Latex file; typos correcte
5D Super Yang-Mills Theory in 4D Superspace, Superfield Brane Operators, and Applications to Orbifold GUTs
A manifestly gauge invariant formulation of 5-dimensional supersymmetric
Yang-Mills theories in terms of 4d superfields is derived. It relies on a
supersymmetry and gauge-covariant derivative operator in the direction.
This formulation allows for a systematic study of higher-derivative operators
by combining invariant 4d superfield expressions under the additional
restriction of 5d Lorentz symmetry. In cases where the 5d theory is
compactified on a gauge-symmetry-breaking orbifold, the formalism can be used
for a simple discussion of possible brane operators invariant under the
restricted symmetry of the fixed points. This is particularly relevant to
recently constructed grand unified theories in higher dimensions (orbifold
GUTs). Several applications, including proton decay operators and
brane-localized mass terms, are discussed.Comment: 14 pages LaTeX, minor corrections, final version to appear in Nuclear
Physics
The F-Landscape: Dynamically Determining the Multiverse
We evolve our Multiverse Blueprints to characterize our local neighborhood of
the String Landscape and the Multiverse of plausible string, M- and F-theory
vacua. Building upon the tripodal foundations of i) the Flipped SU(5) Grand
Unified Theory (GUT), ii) extra TeV-Scale vector-like multiplets derived out of
F-theory, and iii) the dynamics of No-Scale Supergravity, together dubbed
No-Scale F-SU(5), we demonstrate the existence of a continuous family of
solutions which might adeptly describe the dynamics of distinctive universes.
This Multiverse landscape of F-SU(5) solutions, which we shall refer to as the
F-Landscape, accommodates a subset of universes compatible with the presently
known experimental uncertainties of our own universe. We show that by
secondarily minimizing the minimum of the scalar Higgs potential of each
solution within the F-Landscape, a continuous hypervolume of distinct minimum
minimorum can be engineered which comprise a regional dominion of universes,
with our own universe cast as the bellwether. We conjecture that an
experimental signal at the LHC of the No-Scale F-SU(5) framework's
applicability to our own universe might sensibly be extrapolated as
corroborating evidence for the role of string, M- and F-theory as a master
theory of the Multiverse, with No-Scale supergravity as a crucial and pervasive
reinforcing structure.Comment: 15 Pages, 7 Figures, 1 Tabl
Vibrational signature of broken chemical order in a GeS2 glass: a molecular dynamics simulation
Using density functional molecular dynamics simulations, we analyze the
broken chemical order in a GeS glass and its impact on the dynamical
properties of the glass through the in-depth study of the vibrational
eigenvectors. We find homopolar bonds and the frequencies of the corresponding
modes are in agreement with experimental data. Localized S-S modes and 3-fold
coordinated sulfur atoms are found to be at the origin of specific Raman peaks
whose origin was not previously clear. Through the ring size statistics we
find, during the glass formation, a conversion of 3-membered rings into larger
units but also into 2-membered rings whose vibrational signature is in
agreement with experiments.Comment: 11 pages, 8 figures; to appear in Phys. Rev.
Generalizing Minimal Supergravity
In Grand Unified Theories (GUTs), the Standard Model (SM) gauge couplings
need not be unified at the GUT scale due to the high-dimensional operators.
Considering gravity mediated supersymmetry breaking, we study for the first
time the generic gauge coupling relations at the GUT scale, and the general
gaugino mass relations which are valid from the GUT scale to the electroweak
scale at one loop. We define the index k for these relations, which can be
calculated in GUTs and can be determined at the Large Hadron Collider and the
future International Linear Collider. Thus, we give a concrete definition of
the GUT scale in these theories, and suggest a new way to test general GUTs at
future experiments. We also discuss five special scenarios with interesting
possibilities. With our generic formulae, we present all the GUT-scale gauge
coupling relations and all the gaugino mass relations in the SU(5) and SO(10)
models, and calculate the corresponding indices k. Especially, the index k is
5/3 in the traditional SU(5) and SO(10) models that have been studied
extensively so far. Furthermore, we discuss the field theory realization of the
U(1) flux effects on the SM gauge kinetic functions in F-theory GUTs, and
calculate their indices k as well.Comment: RevTex4, 14 pages, 4 tables, references added, version in PL
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