2,506 research outputs found
Improved unitarity constraints in Two-Higgs-Doublet-Models
Two-Higgs-Doublet-Models (THDMs) are among the simplest extensions of the
standard model and are intensively studied in the literature. Using on-shell
parameters such as the masses of the additional scalars as input, corresponds
often to large quartic couplings in the underlying Lagrangian. Therefore, it is
important to check if these couplings are for instance in agreement with
perturbative unitarity. The common approach for doing this check is to consider
the two-particle scattering matrix of scalars in the large centre-of-mass
energy limit where only point interactions contribute. We show that this is not
always a valid approximation: the full calculation including all tree-level
contributions at finite energy can lead to much more stringent constraints. We
show how the allowed regions in the parameter space are affected. In
particular, the light Higgs window with a second Higgs below 125 GeV completely
closes for large values of the breaking parameter . We also
compare against the loop corrected constraints, which use also the large
approximation, and find that (effective) cubic couplings are often
more important than radiative corrections.Comment: 8 pages, 6 figure
The Higgs mass in the CP violating MSSM, NMSSM, and beyond
We discuss the automatised calculation of the Higgs mass in renormalisable
supersymmetric models with complex parameters at the two-loop level. Our setup
is based on the public codes SARAH and SPheno, which can now compute the
two-loop corrections to masses of all neutral scalars in such theories. The
generic ansatz for these calculations and the handling of the `Goldstone Boson
catastrophe' is described. It is shown that we find perfect agreement with
other existing two-loop calculations performed in the DR-bar scheme. We also
use the functionality to derive results for the MSSM and NMSSM not available
before: the Higgs mass in the constrained version of the complex MSSM, and the
impact of CP phases in the two-loop corrections beyond order alpha-strong
alpha-top for the scale invariant NMSSM are briefly analysed.Comment: 19 pages, 14 figure
On the two-loop corrections to the Higgs masses in the NMSSM
We discuss the impact of the two-loop corrections to the Higgs mass in the
NMSSM beyond . For this purpose we use the
combination of the public tools SARAH and SPheno to include all contributions
stemming from superpotential parameters. We show that the corrections in the
case of a heavy singlet are often MSSM-like and reduce the predicted mass of
the SM-like state by about 1 GeV as long as is moderately large. For
larger values of the additional corrections can increase the SM-like
Higgs mass. If a light singlet is present the additional corrections become
more important even for smaller values of and can even dominate the
ones involving the strong interaction. In this context we point out that
important effects are not reproduced quantitatively when only including
corrections known from the MSSM.Comment: 23 pages, 11 figure
Dirac Gauginos and the 125 GeV Higgs
We investigate the mass, production and branching ratios of a 125 GeV Higgs
in models with Dirac gaugino masses. We give a discussion of naturalness, and
describe how deviations from the Standard Model in the key Higgs search
channels can be simply obtained. We then perform parameter scans using a SARAH
package upgrade, which produces SPheno code that calculates all relevant
quantities, including electroweak precision and flavour constraint data, to a
level of accuracy previously impossible for this class of models. We study
three different variations on the minimal Dirac gaugino extension of the
(N)MSSM.Comment: 32 pages, 9 figure
Supersymmetric and non-supersymmetric models without catastrophic Goldstone bosons
The calculation of the Higgs mass in general renormalisable field theories
has been plagued by the so-called "Goldstone Boson Catastrophe", where light
(would-be) Goldstone bosons give infra-red divergent loop integrals. In
supersymmetric models, previous approaches included a workaround that
ameliorated the problem for most, but not all, parameter space regions; while
giving divergent results everywhere for non-supersymmetric models! We present
an implementation of a general solution to the problem in the public code
SARAH, along with new calculations of some necessary loop integrals and generic
expressions. We discuss the validation of our code in the Standard Model, where
we find remarkable agreement with the known results. We then show new
applications in Split SUSY, the NMSSM, the Two-Higgs-Doublet Model, and the
Georgi-Machacek model. In particular, we take some first steps to exploring
where the habit of using tree-level mass relations in non-supersymmetric models
breaks down, and show that the loop corrections usually become very large well
before naive perturbativity bounds are reached.Comment: 45 pages, 12 figure
Shedding light on the anomalies with a dark sector
The LHCb collaboration has recently reported on some anomalies in
transitions. In addition to discrepancies with the Standard Model (SM)
predictions in some angular observables and branching ratios, an intriguing
hint for lepton universality violation was found. Here we propose a simple
model that extends the SM with a dark sector charged under an additional
gauge symmetry. The spontaneous breaking of this symmetry gives rise to a
massive boson, which communicates the SM particles with a valid dark
matter candidate, while solving the anomalies with contributions to
the relevant observables.Comment: 9 pages, 4 figures. Few typos corrected, references adde
The Higgs Mass in the MSSM at two-loop order beyond minimal flavour violation
Soft supersymmetry-breaking terms provide a wealth of new potential sources
of flavour violation, which are tightly constrained by precision experiments.
This has posed a challenge to construct flavour models which both explain the
structure of the Standard Model Yukawa couplings and also predict soft-breaking
patterns that are compatible with these constraints. While such models have
been studied in great detail, the impact of flavour violating soft terms on the
Higgs mass at the two-loop level has been assumed to be small or negligible. In
this letter, we show that large flavour violation in the up-squark sector can
give a positive or negative mass shift to the SM-like Higgs of several GeV,
without being in conflict with other observations. We investigate in which
regions of the parameter space these effects can be expected.Comment: 8 pages, 9 figure
Global digital data sets of soil type, soil texture, surface slope and other properties: Documentation of archived data tape
The file structure and coding of four soils data sets derived from the Zobler (1986) world soil file is described. The data were digitized on a one-degree square grid. They are suitable for large-area studies such as climate research with general circulation models, as well as in forestry, agriculture, soils, and hydrology. The first file is a data set of codes for soil unit, land-ice, or water, for all the one-degree square cells on Earth. The second file is a data set of codes for texture, land-ice, or water, for the same soil units. The third file is a data set of codes for slope, land-ice, or water for the same units. The fourth file is the SOILWRLD data set, containing information on soil properties of land cells of both Matthews' and Food and Agriculture Organization (FAO) sources. The fourth file reconciles land-classification differences between the two and has missing data filled in
Dark matter scenarios in a constrained model with Dirac gauginos
We perform the first analysis of Dark Matter scenarios in a constrained model
with Dirac Gauginos. The model under investigation is the Constrained Minimal
Dirac Gaugino Supersymmetric Standard model (CMDGSSM) where the Majorana mass
terms of gauginos vanish. However, -symmetry is broken in the Higgs sector
by an explicit and/or effective -term. This causes a mass splitting
between Dirac states in the fermion sector and the neutralinos, which provide
the dark matter candidate, become pseudo-Dirac states. We discuss two
scenarios: the universal case with all scalar masses unified at the GUT scale,
and the case with non-universal Higgs soft-terms. We identify different regions
in the parameter space which fullfil all constraints from the dark matter
abundance, the limits from SUSY and direct dark matter searches and the Higgs
mass. Most of these points can be tested with the next generation of direct
dark matter detection experiments.Comment: 28 pages, 11 figures; v2: minor changes, title modified; matches
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