128 research outputs found
FlexibleSUSY -- A spectrum generator generator for supersymmetric models
We introduce FlexibleSUSY, a Mathematica and C++ package, which generates a
fast, precise C++ spectrum generator for any SUSY model specified by the user.
The generated code is designed with both speed and modularity in mind, making
it easy to adapt and extend with new features. The model is specified by
supplying the superpotential, gauge structure and particle content in a SARAH
model file; specific boundary conditions e.g. at the GUT, weak or intermediate
scales are defined in a separate FlexibleSUSY model file. From these model
files, FlexibleSUSY generates C++ code for self-energies, tadpole corrections,
renormalization group equations (RGEs) and electroweak symmetry breaking (EWSB)
conditions and combines them with numerical routines for solving the RGEs and
EWSB conditions simultaneously. The resulting spectrum generator is then able
to solve for the spectrum of the model, including loop-corrected pole masses,
consistent with user specified boundary conditions. The modular structure of
the generated code allows for individual components to be replaced with an
alternative if available. FlexibleSUSY has been carefully designed to grow as
alternative solvers and calculators are added. Predefined models include the
MSSM, NMSSM, ESSM, USSM, R-symmetric models and models with right-handed
neutrinos.Comment: 56 pages, 3 figures, 3 tables; v3: correcting typos, matches version
accepted for publication by CP
FlexibleSUSY – a meta spectrum generator for supersymmetric models
AbstractFlexibleSUSY is a software package that takes as input descriptions of (non-)minimal supersymmetric models written in Wolfram/Mathematica and generates a set of spectrum generator libraries and executables, with the aid of SARAH. The design goals are precision, reliability, modularity, speed, and readability of the code. The boundary conditions are independent C++ objects that are plugged into the boundary value problem solver together with the model objects. This clean separation makes it easy to adapt the generated code for individual projects. The current status of the interface and implementation is sketched
Higgs mass prediction in the MSSM at three-loop level in a pure context
The impact of the three-loop effects of order on the
mass of the light CP-even Higgs boson in the MSSM is studied in a pure
context. For this purpose, we implement the results of
Kant et al. into the C++ module Himalaya and link it to FlexibleSUSY, a
Mathematica and C++ package to create spectrum generators for BSM models. The
three-loop result is compared to the fixed-order two-loop calculations of the
original FlexibleSUSY and of FeynHiggs, as well as to the result based on an
EFT approach. Aside from the expected reduction of the renormalization scale
dependence with respect to the lower order results, we find that the three-loop
contributions significantly reduce the difference from the EFT prediction in
the TeV-region of the SUSY scale . Himalaya can be linked also to other
two-loop codes, thus allowing for the elevation of these
codes to the three-loop level.Comment: 32 pages, 8 figures, 1 table [version submitted to EPJC
Higgs mass predictions of public NMSSM spectrum generators
The publicly available spectrum generators for the NMSSM often lead to
different predictions for the mass of the standard model-like Higgs boson even
if using the same renormalization scheme and two-loop accuracy. Depending on
the parameter point, the differences can exceed 5 GeV, and even reach 8 GeV for
moderate superparticle masses of up to 2 TeV. It is shown here that these
differences can be traced back to the calculation of the running standard model
parameters entering all calculations, to the approximations used in the
two-loop corrections included in the different codes, and to different choices
for the renormalization conditions and scales. In particular, the importance of
the calculation of the top Yukawa coupling is pointed out.Comment: 24 pages, no figures; v2: slightly extended discussion, matches
version accepted for publication by CP
Mass spectrum prediction in non-minimal supersymmetric models
Supersymmetry is an attractive extension of the Standard Model (SM) of particle physics. The minimal supersymmetric extension (MSSM) provides gauge coupling unification, a dark matter candidate particle and can explain the breaking of the electroweak symmetry dynamically. However, it suffers from the little hierarchy and the mu-problem.
Non-minimal supersymmetric extensions of the SM with a larger particle content or a higher symmetry can evade the problems of the MSSM. Such models may be well-motivated by Grand Unified Theories (GUTs) and can provide a rich new phenomenology with an extended Higgs sector, exotic particles, additional interactions and a close connection to String Theory. Interesting examples are the Next-to Minimal Supersymmetric Standard Model (NMSSM), which is motivated by the mu-problem, and the Exceptional Supersymmetric Standard Model (E6SSM), which is inspired by E6 GUTs.
For phenomenological investigations of supersymmetric (SUSY) models the pole mass spectrum must be calculated from the fundamental model parameters. This task, however, is non-trivial as the spectrum must be consistent with measured low-energy observables (fine-structure constant, Z boson pole mass, muon decay etc.) as well as electroweak symmetry breaking and potential universality conditions on the soft supersymmetry breaking parameters at the GUT scale.
Programs, which calculate the SUSY mass spectrum consistent with constraints of this kind are called spectrum generators.
In this thesis four different contributions to the prediction of mass spectra and model parameters in non-minimal SUSY models are presented. (i) One-loop matching corrections of the E6SSM gauge and Yukawa couplings to the SM are calculated to increase the precision of the mass spectrum prediction in the constrained E6SSM. (ii) The beta-functions of vacuum expectation values (VEVs) are calculated in a general and supersymmetric gauge theory at the one- and two-loop level. The results enable an accurate calculation of the renormalization group running of the VEVs in non-minimal SUSY models. (iii) An NMSSM extension of Softsusy, a spectrum generator for the MSSM, is implemented. It represents a precise alternative to the already existing spectrum generator NMSPEC. (iv) FlexibleSUSY is presented, a general framework which creates a fast, modular and precise spectrum generator for any user-defined SUSY model. It represents a generalization of the hand-written SUSY spectrum generators and allows the study of a large variety of new SUSY models easily with high precision
FlexibleSUSY: Precise automated calculations in any BSM theory
FlexibleSUSY is a software package for various calculations in any model of
physics beyond the standard model (not just any supersymmetric model).
FlexibleSUSY can solve boundary value problems and uses this to find
parameters and calculate the Higgs and BSM
particle masses, as well as other observables. FlexibleSUSY is designed to be
adaptable, fast, precise and reliable. We describe FlexibleSUSY with particular
emphasis on recent developments and the state of the art Higgs mass
calculations it can perform. We also show some applications to illustrate how
it can be used to obtain interesting physics results with the highest precision
possible and with remarkable speed.Comment: 4 pages plus title page, 1 figure. Contribution to proceedings of
ICHEP 2018, the 39th International Conference on High Energy Physic
Precision tools and models to narrow in on the 750 GeV diphoton resonance
The hints for a new resonance at 750 GeV from ATLAS and CMS have triggered a
significant amount of attention. Since the simplest extensions of the standard
model cannot accommodate the observation, many alternatives have been
considered to explain the excess. Here we focus on several proposed
renormalisable weakly-coupled models and revisit results given in the
literature. We point out that physically important subtleties are often missed
or neglected. To facilitate the study of the excess we have created a
collection of 40 model files, selected from recent literature, for the
Mathematica package SARAH. With SARAH one can generate files to perform
numerical studies using the tailor-made spectrum generators FlexibleSUSY and
SPheno. These have been extended to automatically include crucial higher order
corrections to the diphoton and digluon decay rates for both CP-even and CP-odd
scalars. Additionally, we have extended the UFO and CalcHep interfaces of
SARAH, to pass the precise information about the effective vertices from the
spectrum generator to a Monte-Carlo tool. Finally, as an example to demonstrate
the power of the entire setup, we present a new supersymmetric model that
accommodates the diphoton excess, explicitly demonstrating how a large width
can be obtained. We explicitly show several steps in detail to elucidate the
use of these public tools in the precision study of this model.Comment: 184 pages, 24 figures; model files available at
http://sarah.hepforge.org/Diphoton_Models.tar.gz; v2: added a few
clarifications and reference
FlexibleDecay: An automated calculator of scalar decay widths
We present FlexibleDecay, a tool to calculate decays of scalars in a broad
class of BSM models. The tool aims for high precision particularly in the case
of Higgs boson decays. In the case of scalar and pseudoscalar Higgs boson
decays the known higher order SM QED, QCD and EW effects are taken into account
where possible. The program works in a modified scheme that
exhibits a decoupling property with respect to heavy BSM physics, with BSM
parameters themselves treated in the -scheme
allowing for an easy connection to high scale tests for, e.g., perturbativity
and vacuum stability, and the many observable calculations readily available in
programs. Pure BSM effects are taken into
account at the leading order, including all one-loop contributions to
loop-induced processes. The program is implemented as an extension to
FlexibleSUSY, which determines the mass spectrum for arbitrary BSM models, and
does not require any extra configuration from the user. We compare our
predictions for Higgs decays in the SM, singlet extended SM, type II THDM,
CMSSM and MRSSM, as well as for squark decays in the CMSSM against a selection
of publicly available tools. The numerical differences between our and other
programs are explained. The release of FlexibleDecay officially deprecates the
old effective couplings routines in FlexibleSUSY.Comment: 44 pages, 3 figures, 11 tables; version published in CP
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