Soft Supersymmetry Breaking Parameters Research Articles

SuSpect3: A C++ code for the supersymmetric and Higgs particle spectrum of the MSSM

We present the program SuSpect3 that calculates the masses and couplings of the Higgs and supersymmetric particles predicted by the Minimal Supersymmetric Standard Model (MSSM). The model is implemented in both its non-constrained version, the MSSM, and its constrained versions, such as the minimal supergravity and the gauge or anomaly mediated supersymmetry breaking models, in which the soft supersymmetry–breaking parameters obey certain universal boundary conditions at the high energy scale. The low energy parameters are then obtained using renormalization group equations and electroweak symmetry breaking, and all the dominant radiative corrections have been consistently implemented. SuSpect3 is a major rewrite, in C++ object oriented programming, of the FORTRAN code SuSpect. It includes all the features of the earlier code in an improved and updated manner, and involves new options such as compressed SUSY scenarios, an MSSM-inflation model and the possibility of using the observed Higgs mass as an input. The main features and the use of the program are explained. Program summaryProgram Title:SuSpect3CPC Library link to program files:https://doi.org/10.17632/55jv4kdrm8.1Developer's repository link:http://suspect.in2p3.frLicensing provisions: GPLv3Programming language:C++, compatible C++98, C++11, C++14, C++17Nature of problem: Supersymmetric models such as the MSSM, mSUGRA, GMSB, AMSB and others have specific parameter sets and boundary conditions. SuSpect3 translates the parameter sets of the models into predictions of the Higgs and supersymmetric particles masses. The mixing matrices of the physical states as well as the mixing angles are calculated in addition to the scale dependent parameters.Solution method: The spectrum of the Higgs and supersymmetric particles depends on the model, its supersymmetric parameter set and the Standard Model parameters. The evolution of the parameters as function of the energy scale is calculated by solving numerically the Renormalization Group Equations. Model dependent boundary conditions are applied at the appropriate scale. Electroweak symmetry breaking is calculated iteratively at the electroweak scale. The application of radiative corrections translate the scale dependent particle masses into the physical pole masses.Additional comments including restrictions and unusual features: The parameters and physical masses are defined to be real. Warnings are issued if intermediate results are unphysical.Compiles with gcc-4.8.5 and later (checked with gcc-8.1.0).

Flipped SU(5) GUT phenomenology: proton decay and mathbf {g_mu - 2}

We consider proton decay and g_mu - 2 in flipped SU(5) GUT models. We first study scenarios in which the soft supersymmetry-breaking parameters are constrained to be universal at some high scale M_{in} above the standard GUT scale where the QCD and electroweak SU(2) couplings unify. In this case the proton lifetime is typically > rsim 10^{36} years, too long to be detected in the foreseeable future, and the supersymmetric contribution to g_mu - 2 is too small to contribute significantly to resolving the discrepancy between the experimental measurement and data-driven calculations within the Standard Model. However, we identify a region of the constrained flipped SU(5) parameter space with large couplings between the 10- and 5-dimensional GUT Higgs representations where p rightarrow e^+ pi ^0 decay may be detectable in the Hyper-Kamiokande experiment now under construction, though the contribution to g_mu -2 is still small. A substantial contribution to g_mu - 2 is possible, however, if the universality constraints on the soft supersymmetry-breaking masses are relaxed. We find a ‘quadrifecta’ region where observable proton decay co-exists with a (partial) supersymmetric resolution of the g_mu - 2 discrepancy and acceptable values of m_h and the relic LSP density.

Distribution of supersymmetry μ parameter and Peccei-Quinn scale fa from the landscape

A scan of soft supersymmetry (SUSY) breaking parameters within the string theory landscape with the minimal supersymmetric standard model assumed as the low energy effective field theory---using a power-law draw to large soft terms coupled with an anthropic selection of a derived weak scale to be within a factor of 4 of our measured value---predicts a peak probability of ${m}_{h}\ensuremath{\simeq}125\text{ }\text{ }\mathrm{GeV}$ with sparticle masses typically beyond the reach of LHC Run 2. Such multiverse simulations usually assume a fixed value of the SUSY conserving superpotential $\ensuremath{\mu}$ parameter to be within the assumed anthropic range, $\ensuremath{\mu}\ensuremath{\lesssim}350\text{ }\text{ }\mathrm{GeV}$. However, depending on the assumed solution to the SUSY $\ensuremath{\mu}$ problem, the expected $\ensuremath{\mu}$ term distribution can actually be derived. In this paper, we examine two solutions to the SUSY $\ensuremath{\mu}$ problem. The first is the gravity-safe-Peccei-Quinn model based on an assumed ${\mathbb{Z}}_{24}^{R}$ discrete $R$-symmetry which allows a gravity-safe accidental, approximate Peccei-Quinn global symmetry to emerge which also solves the strong $CP$ problem. The second case is the Giudice-Masiero solution wherein the $\ensuremath{\mu}$ term effectively acts as a soft term and has a linear draw to large values. For the first case, we also present the expected landscape distribution for the Peccei-Quinn scale ${f}_{a}$; in this case, weak scale anthropics limits its range to the cosmological sweet zone of around ${f}_{a}\ensuremath{\sim}{10}^{11}\text{ }\text{ }\mathrm{GeV}$.

A minimal supersymmetric SU(5) missing-partner model

We explore a missing-partner model based on the minimal SU(5) gauge group with mathbf{75} , mathbf{50} and overline{mathbf{50 }} Higgs representations, assuming a super-GUT CMSSM scenario in which soft supersymmetry-breaking parameters are universal at some high scale M_{mathrm{in}} above the GUT scale M_{mathrm{GUT}}. We identify regions of parameter space that are consistent with the cosmological dark matter density, the measured Higgs mass and the experimental lower limit on tau (p rightarrow K^+ nu ). These constraints can be satisfied simultaneously along stop coannihilation strips in the super-GUT CMSSM with tan beta sim 3.5–5 where the input gaugino mass m_{1/2} sim 15–25 TeV, corresponding after strong renormalization by the large GUT Higgs representations between M_{mathrm{in}} and M_{mathrm{GUT}} to m_{mathrm{LSP}}, m_{{tilde{t}}_1} sim 2.5–5 TeV and m_{{tilde{g}}} sim 13–20 TeV, with the light-flavor squarks significantly heavier. We find that tau (p rightarrow K^+ nu ) lesssim 3 times 10^{34} years throughout the allowed range of parameter space, within the range of the next generation of searches with the JUNO, DUNE and Hyper-Kamiokande experiments.

Constraining Affleck-Dine leptogenesis after thermal inflation

Affleck-Dine leptogenesis after thermal inflation along the LHu direction requires mL2+mHu2 < 0 up to the AD scale (|L|≃|Hu|∼ 109 GeV). We renormalised this condition from the AD scale to the soft supersymmetry breaking scale by solving the renormalisation group equations perturbatively in the Yukawa couplings to obtain a semi-analytic constraint on the soft supersymmetry breaking parameters, which is much stronger than the tree-level result. We also used a fully numerical method to renormalise the baryogenesis condition and constrained the Minimal Supersymmetric Cosmological Model using the resulting baryogenesis condition and other constraints, specifically, electroweak symmetry breaking, the observed Higgs mass, and the axion and axino dark matter abundance.

Sgoldstino signature in hh, W+W\u2212 and ZZ spectra at the LHC

In a supersymmetric extension of the Standard Model of particle physics (SM) with low scale of supersymmetry breaking, sgoldstino of (sub)TeV mass can be observed at the Large Hadron Collider (LHC) as a peak in diboson mass spectra. Moreover, as a singlet with respect to the SM gauge group, scalar sgoldstino can mix with the SM-like Higgs boson and interfere in all neutral channels providing with the promising signatures of new physics if superpartners are heavy. Sgoldstino couplings to the SM particles are determined by the pattern of soft supersymmetry breaking parameters. Here we concentrate on the cases with a noticeable sgoldstino contribution to di-Higgs channel. Having found a phenomenologically viable region in the model parameter space where scalar sgoldstino, produced at the LHC in gluon fusion, decays into a pair of the lightest Higgs boson we give predictions for corresponding cross section. Using the results of the LHC searches for scalar resonances we place bounds on the supersymmetry breaking scale sqrt{F} in this region of parameter space. Remarkably, in this region sgoldstino may also be observed in W+W− and ZZ channels, yielding independent signatures, since their signal strengths are related to that of di-Higgs channel.

Supersymmetric proton decay revisited

Encouraged by the advent of a new generation of underground detectors – JUNO, DUNE and Hyper-Kamiokande – that are projected to improve significantly on the present sensitivities to various baryon decay modes, we revisit baryon decay in the minimal supersymmetric SU(5) GUT. We discuss the phenomenological uncertainties associated with hadronic matrix elements and the value of the strong coupling alpha _s – which are the most important – the weak mixing angle theta _W, quark masses including one-loop renormalization effects, quark mixing and novel GUT phases that are not visible in electroweak interaction processes. We apply our analysis to a variety of CMSSM, super- and sub-GUT scenarios in which soft supersymmetry-breaking parameters are assumed to be universal at, above and below the GUT scale, respectively. In many cases, we find that the next generation of underground detectors should be able to probe models with sparticle masses that are {{mathcal {O}}}(10) TeV, beyond the reach of the LHC.

R-parity violating decays of Bino neutralino LSPs at the LHC

The R-parity violating decays of Bino neutralino LSPs are analyzed within the context of the B − L MSSM “heterotic standard model”. These LSPs correspond to statistically determined initial soft supersymmetry breaking parameters which, when evolved using the renormalization group equations, lead to an effective theory satisfying all phenomenological requirements; including the observed electroweak vector boson masses and the Higgs mass. The explicit RPV decay channels of these LSPs into standard model particles, the analytic and numerical decay rates and the associated branching ratios are presented. The analysis of these quantities breaks into two separate calculations; first, for Bino neutralino LSPs with mass larger than MW± and, second, when the Bino neutralino mass is smaller than the electroweak scale. The RPV decay processes in both of these regions is analyzed in detail. The decay lengths of these RPV interactions are discussed. It is shown that for heavy Bino neutralino LSPs the vast majority of these decays are “prompt”, although a small, but calculable, number correspond to “displaced” decays of various lengths. The situation is reversed for light Bino LSPs, only a small number of which can RPV decay promptly. The relation of these results to the neutrino hierarchy — either normal or inverted — is discussed in detail.

Hide and Seek with Massive Fields in Modulus Mediation.

We study the modulus mediation of supersymmetry breaking motivated by superstring theory. We show that the renormalization group running of the soft supersymmetry breaking parameters due to the interactions of massive fields is canceled by the threshold corrections at one-loop order, if their mass is given by nonperturbative dynamics controlled by the same modulus that mediates supersymmetry breaking and a sum rule of the modular weights holds for the Yukawa couplings. As an example, we discuss order reduction of lepton flavor violation in the supersymmetric seesaw mechanism, which revives the parameter space already excluded.

Sizable stop mixing in flavored gauge mediation models with discrete non-Abelian symmetries

We analyze a minimal flavored gauge mediation model in which the electroweak Higgs and messenger doublets are embedded in multiplets of a discrete non-Abelian symmetry. In this scenario, the minimal Higgs-messenger sector that is consistent with the 125 GeV Higgs mass has two vectorlike pairs of messenger fields. This scenario is obtained in a specific limit of the superpotential interactions of the Higgs-messenger fields and the matter fields. Due to the structure of the messenger-matter Yukawa couplings in this limit, sizable stop mixing and flavor-diagonal soft supersymmetry breaking parameters are achieved. In most of the parameter space, the masses of the colored superpartners are at most in the 5-6 TeV range.

R-parity violating decays of Wino chargino and wino neutralino LSPs and NLSPs at the LHC

The R-parity violating decays of both Wino chargino and Wino neutralino LSPs are analyzed within the context of the B − L MSSM “heterotic standard model”. These LSPs correspond to statistically determined initial soft supersymmetry breaking parameters which, when evolved using the renormalization group equations, lead to an effective theory satisfying all phenomenological requirements; including the observed electroweak vector boson and Higgs masses. The explicit decay channels of these LSPs into standard model particles, the analytic and numerical decay rates and the associated branching ratios are presented. The decay lengths of these RPV interactions are discussed. It is shown that the vast majority of these decays are “prompt”, although a small, but calculable, number correspond to “displaced vertices” of various lengths. It is demonstrated that for a Wino chargino LSP, the NLSP is the Wino neutralino with a mass only slightly higher than the LSP — and vice-versa. As a consequence, we show that both the Wino chargino and Wino neutralino LSP/NLSP R-parity violating decays should be simultaneously observable at the CERN LHC.

The R-parity violating decays of charginos and neutralinos in the B-L MSSM

The B − L MSSM is the MSSM with three right-handed neutrino chiral multiplets and gauged B − L symmetry. The B − L symmetry is broken by the third family right-handed sneutrino acquiring a VEV, thus spontaneously breaking R-parity. Within a natural range of soft supersymmetry breaking parameters, it is shown that a large and uncorrelated number of initial values satisfy all present phenomenological constraints; including the correct masses for the W±, Z0 bosons, having all sparticles exceeding their present lower bounds and giving the experimentally measured value for the Higgs boson. For this “valid” set of initial values, there are a number of different LSPs, each occurring a calculable number of times. We plot this statistically and determine that among the most prevalent LSPs are chargino and neutralino mass eigenstates. In this paper, the R-parity violating decay channels of charginos and neutralinos to standard model particles are determined, and the interaction vertices and decay rates computed analytically. These results are valid for any chargino and neutralino, regardless of whether or not they are the LSP. For chargino and neutralino LSPs, we will — in a subsequent series of papers — present a numerical study of their RPV decays evaluated statistically over the range of associated valid initial points.

Revisiting flavor and CP violation in supersymmetric SU(5) with right-handed neutrinos

We revisit the minimal supersymmetric SU(5) grand unified theory with three right-handed neutrinos in which universality conditions for soft-supersymmetry breaking parameters are imposed at an input scale above the unification scale. If the Majorana masses for the neutrinos are around $10^{15}$ GeV, large mixing angles and phases in the neutrino sector lead to flavor-violation and CP-violation in the right-handed down squark and left-handed slepton sectors. Since the observed Higgs boson mass and the proton decay constraints indicate sfermions have masses larger than a few TeV, flavor and CP constraints are less restrictive. We explore the constraints on models with a universal soft-supersymmetry breaking input parameters coming from proton stability, electric dipole moments, $\mu\to e\gamma$ decays, and the Higgs mass observed at the LHC. Regions compatible with all constraints can be found if non-zero A-terms are taken.

Dark matter, sparticle spectroscopy and muon (g \u2212 2) in SU(4)c \xd7 SU(2)L \xd7 SU(2)R

We explore the sparticle mass spectra including LSP dark matter within the framework of supersymmetric SU(4)c × SU(2)L × SU(2)R (422) models, taking into account the constraints from extensive LHC and cold dark matter searches. The soft supersymmetry-breaking parameters at MGUT can be non-universal, but consistent with the 422 symmetry. We identify a variety of coannihilation scenarios compatible with LSP dark matter, and study the implications for future supersymmetry searches and the ongoing muon g-2 experiment.

Perturbative reheating in Sneutrino-Higgs cosmology

The theory of perturbative reheating in the Sneutrino-Higgs cosmology of the B-L MSSM is presented. It is shown that following an epoch of inflation consistent with all Planck2015 data, the inflaton begins to oscillate around its minimum at zero and to reheat to various species of standard model and supersymmetric matter. The perturbative decay rates to this matter are computed, both analytically and numerically. Using these results, the Hubble parameter and the relative energy densities for each matter species, including that of the inflaton, are calculated numerically. The inflaton energy density is demonstrated to vanish at an energy scale of mathcal{O} (1013) GeV, signaling the end of the period of reheating. The newly created matter background is shown to be in thermal equilibrium, with a reheating temperature of ≃ 1.13 × 1013 GeV. To allow for a B-L breaking scale sufficiently smaller than the reheating scale, we extend the statistical method of determining the soft supersymmetry breaking parameters developed in previous work. The result is that one can determine a large number of phenomenologically realistic initial conditions for which the B-L breaking scale is an order of magnitude or more smaller than the reheating scale.

The Constrained NMSSM with right-handed neutrinos

In this article, we demonstrate that the inclusion of right-handed neutrino superfields in the Next-to-Minimal Supersymmetric Standard Model (NMSSM) makes it possible to impose universality conditions on the soft supersymmetry-breaking parameters at the Grand Unification scale, alleviating many of the problems of the so-called Constrained NMSSM. We have studied the renormalization group equations of this model, showing that right-handed neutrinos greatly contribute to driving the singlet Higgs mass-squared parameter negative, which makes it considerably easier to satisfy the conditions for radiative electroweak symmetry breaking. The new fields also lead to larger values of the Standard Model Higgs mass, thus making it easier to reproduce the measured value. As a consequence, all bounds from colliders and low-energy observables can be fulfilled in wide areas of the parameter space. However, the relic density in these regions is generally too high requiring some form of late entropy production to dilute the density of the lightest supersymmetric particle.

Likelihood analysis of the sub-GUT MSSM in light of LHC 13-TeV data

We describe a likelihood analysis using MasterCode of variants of the MSSM in which the soft supersymmetry-breaking parameters are assumed to have universal values at some scale M_mathrm{in} below the supersymmetric grand unification scale M_mathrm{GUT}, as can occur in mirage mediation and other models. In addition to M_mathrm{in}, such ‘sub-GUT’ models have the 4 parameters of the CMSSM, namely a common gaugino mass m_{1/2}, a common soft supersymmetry-breaking scalar mass m_0, a common trilinear mixing parameter A and the ratio of MSSM Higgs vevs tan beta , assuming that the Higgs mixing parameter mu > 0. We take into account constraints on strongly- and electroweakly-interacting sparticles from sim 36/fb of LHC data at 13 TeV and the LUX and 2017 PICO, XENON1T and PandaX-II searches for dark matter scattering, in addition to the previous LHC and dark matter constraints as well as full sets of flavour and electroweak constraints. We find a preference for M_mathrm{in}sim 10^5 to 10^9 ,, mathrm {GeV}, with M_mathrm{in}sim M_mathrm{GUT} disfavoured by Delta chi ^2 sim 3 due to the mathrm{BR}(B_{s, d} rightarrow mu ^+mu ^-) constraint. The lower limits on strongly-interacting sparticles are largely determined by LHC searches, and similar to those in the CMSSM. We find a preference for the LSP to be a Bino or Higgsino with m_{tilde{chi }^0_{1}} sim 1 ,, mathrm {TeV}, with annihilation via heavy Higgs bosons H / A and stop coannihilation, or chargino coannihilation, bringing the cold dark matter density into the cosmological range. We find that spin-independent dark matter scattering is likely to be within reach of the planned LUX-Zeplin and XENONnT experiments. We probe the impact of the (g-2)_mu constraint, finding similar results whether or not it is included.

Low-mass neutralino dark matter in supergravity scenarios: phenomenology and naturalness

The latest experimental results from the LHC and dark matter (DM) searches suggest that the parameter space allowed in supersymmetric theories is subject to strong reductions. These bounds are especially constraining for scenarios entailing light DM particles. Previous studies have shown that light neutralino DM in the Minimal Supersymmetric Standard Model (MSSM), with parameters defined at the electroweak scale, is still viable when the low energy spectrum of the model features light sleptons, in which case, the relic density constraint can be fulfilled. In view of this, we have investigated the viability of light neutralinos as DM candidates in the MSSM, with parameters defined at the grand unification scale. We have analysed the optimal choices of non-universalities in the soft supersymmetry-breaking parameters for both, gauginos and scalars, in order to avoid the stringent experimental constraints. We show that light neutralinos, with a mass as low as 25 GeV, are viable in supergravity scenarios if the gaugino mass parameters at high energy are very non universal, while the scalar masses can remain of the same order. These scenarios typically predict a very small cross section of neutralinos off protons and neutrons, thereby being very challenging for direct detection experiments. However, a potential detection of smuons and selectrons at the LHC, together with a hypothetical discovery of a gamma-ray signal from neutralino annihilations in dwarf spheroidal galaxies could shed light on this kind of solutions. Finally, we have investigated the naturalness of these scenarios, taking into account all the potential sources of tuning. Besides the electroweak fine-tuning, we have found that the tuning to reproduce the correct DM relic abundance and that to match the measured Higgs mass can also be important when estimating the total degree of naturalness.

Thermal inflation with flaton chemical potential

Thermal inflation driven by a scalar field called "flaton" is a possible scenario to solve the cosmological moduli problem. We study a model of thermal inflation with a flaton chemical potential. In the presence of the chemical potential, a negative mass squared of the flaton, which is necessary to terminate the thermal inflation, is naturally induced. We identify the allowed parameter region for the chemical potential ($\mu$) and the flaton self-coupling constant to solve the cosmological moduli problem and satisfy theoretical consistencies. In general, the chemical potential is a free parameter and it can be taken to be much larger than the typical scale of soft supersymmetry breaking parameters of $\mathcal{O} (1)$ TeV. For $\mu \gtrsim 10^8$ GeV, we find that the reheating temperature after the thermal inflation can be high enough for the thermal leptogenesis scenario to be operative. This is in sharp contrast to the standard thermal inflation scenario, in which the reheating temperature is quite low and a special mechanism is necessary for generating sufficient amount of baryon asymmetry in the Universe after thermal inflation.

No-scale SU(5) super-GUTs

We reconsider the minimal SU(5) grand unified theory (GUT) in the context of no-scale supergravity inspired by string compactification scenarios, assuming that the soft supersymmetry-breaking parameters satisfy universality conditions at some input scale M_mathrm{in} above the GUT scale M_{mathrm{GUT}}. When setting up such a no-scale super-GUT model, special attention must be paid to avoiding the Scylla of rapid proton decay and the Charybdis of an excessive density of cold dark matter, while also having an acceptable mass for the Higgs boson. We do not find consistent solutions if none of the matter and Higgs fields are assigned to twisted chiral supermultiplets, even in the presence of Giudice–Masiero terms. However, consistent solutions may be found if at least one fiveplet of GUT Higgs fields is assigned to a twisted chiral supermultiplet, with a suitable choice of modular weights. Spin-independent dark matter scattering may be detectable in some of these consistent solutions.