Supersymmetry Breaking Parameters Research Articles

The heavy gravitino, naturalness, and sizable anomaly mediation

We consider the situation in which $m_{3/2}\sim O(100{\rm TeV})$ for solving the gravitino problem and the other supersymmetry(SUSY) breaking parameters are $O(1{\rm TeV})$ for the naturalness. We point out that the anomaly mediation cancels out the renormalization group contribution to the gaugino masses and the sfermion masses other than the stop masses at a scale which is called the mirage scale. The situation is similar to the mirage mediation, in which special boundary conditions for the SUSY breaking parameters are required, though for the stop masses and the up-type Higgs mass, such cancellation at the mirage scale does not happen. Despite no cancellation for the up-type Higgs mass, we show that the little hierarchy problem becomes less severe in this situation. One advantage of this situation over the mirage mediation is that the stop mixing parameter $A_t$ can be larger and therefore, smaller stop mass is sufficient for 125 GeV Higgs. When the mirage scale is around TeV scale, the SUSY breaking parameters induced by the gravity mediation at the grand unification scale can be observed directly by the TeV scale experiments.

The 126 GeV Higgs boson mass and naturalness in (deflected) mirage mediation

We study the mass of the lightest CP-even Higgs boson in the deflected mirage mediation that is a quite general framework of the mediation of supersymmetry breaking, incorporating the case where all of the modulus-, the anomaly- and the gauge-mediated contributions to the soft supersymmetry breaking parameters become sizable. We evaluate the degree of tuning the so-called μ parameter required for realizing a correct electroweak symmetry breaking and study how to accomplish both the observed Higgs boson mass and the relaxed fine-tuning. We identify the parameter space favored from such a perspective and show the superparticle mass spectrum with some input parameters inside the indicated region. The results here would be useful when we aim to prove the communication between the visible and the hidden sectors in supergravity and superstring models based on the recent observations.

Next-to-minimal SOFTSUSY

We describe an extension to the SOFTSUSY program that provides for the calculation of the sparticle spectrum in the Next-to-Minimal Supersymmetric Standard Model (NMSSM), where a chiral superfield that is a singlet of the Standard Model gauge group is added to the Minimal Supersymmetric Standard Model (MSSM) fields. Often, a Z3 symmetry is imposed upon the model. SOFTSUSY can calculate the spectrum in this case as well as the case where general Z3 violating (denoted as ▪) terms are added to the soft supersymmetry breaking terms and the superpotential. The user provides a theoretical boundary condition for the couplings and mass terms of the singlet. Radiative electroweak symmetry breaking data along with electroweak and CKM matrix data are used as weak-scale boundary conditions. The renormalisation group equations are solved numerically between the weak scale and a high energy scale using a nested iterative algorithm. This paper serves as a manual to the NMSSM mode of the program, detailing the approximations and conventions used. Program SummaryProgram title: SOFTSUSYCatalogue identifier: ADPM_v4_0Program summary URL:http://cpc.cs.qub.ac.uk/summaries/ADPM_v4_0.htmlProgram obtainable from: CPC Program Library, Queen’s University, Belfast, N. IrelandLicensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.htmlNo. of lines in distributed program, including test data, etc.: 154886No. of bytes in distributed program, including test data, etc.: 1870890Distribution format: tar.gzProgramming language: C++, fortran.Computer: Personal computer.Operating system: Tested on Linux 3.x.Word size: 64 bitsClassification: 11.1, 11.6.Does the new version supersede the previous version?: YesCatalogue identifier of previous version: ADPM_v3_0Journal reference of previous version: Comput. Phys. Comm. 183 (2012) 785Nature of problem: Calculating supersymmetric particle spectrum and mixing parameters in the next-to-minimal supersymmetric standard model. The solution to the renormalisation group equations must be consistent with boundary conditions on supersymmetry breaking parameters, as well as on the weak-scale boundary condition on gauge couplings, Yukawa couplings and the Higgs potential parameters.Solution method: Nested iterative algorithm and numerical minimisation of the Higgs potential.Reasons for new version: Major extension to include the next-to-minimal supersymmetric standard model.Summary of revisions: Added additional supersymmetric and supersymmetry breaking parameters associated with the additional gauge singlet. Electroweak symmetry breaking conditions are significantly changed in the next-to-minimal mode, and some sparticle mixing changes. An interface to NMSSMTools has also been included. Some of the object structure has also changed, and the command line interface has been made more user friendly.Restrictions: SOFTSUSY will provide a solution only in the perturbative regime and it assumes that all couplings of the model are real (i.e. CP-conserving). If the parameter point under investigation is non-physical for some reason (for example because the electroweak potential does not have an acceptable minimum), SOFTSUSY returns an error message.Running time: A few seconds per parameter point.

General focus point in the MSSM

The minimal supersymmetric extension of the Standard Model (SM) is a well motivated scenario for physics beyond the SM, which allows a perturbative description of the theory up to scales of the order of the Grand Unification scale, where gauge couplings unify. The Higgs mass parameter is insensitive to the ultraviolet physics and is only sensitive to the scale of soft supersymmetry breaking parameters. Present collider bounds suggest that the characteristic values of these parameters may be significantly larger than the weak scale. Large values of the soft breaking parameters, however, induce large radiative corrections to the Higgs mass parameter and therefore the proper electroweak scale may only be obtained by a fine tuned cancellation between the square of the holomorphic \mu-parameter and the Higgs supersymmetry breaking square mass parameter. This can only be avoided if there is a correlation between the scalar and gaugino mass parameters, such that the Higgs supersymmetry breaking parameter remains of the order of the weak scale. The scale at which this happens is dubbed as focus point. In this article, we define the general conditions required for this to happen, for different values of the messenger scale at which supersymmetry breaking is transmitted to the observable sector, and for arbitrary boundary conditions of the sfermion, gaugino, and Higgs mass parameters. Specific supersymmetry breaking scenarios in which these correlations may occur are also discussed.

Implications of improved Higgs mass calculations for supersymmetric models.

We discuss the allowed parameter spaces of supersymmetric scenarios in light of improved Higgs mass predictions provided by FeynHiggs 2.10.0. The Higgs mass predictions combine Feynman-diagrammatic results with a resummation of leading and subleading logarithmic corrections from the stop/top sector, which yield a significant improvement in the region of large stop masses. Scans in the pMSSM parameter space show that, for given values of the soft supersymmetry-breaking parameters, the new logarithmic contributions beyond the two-loop order implemented in FeynHiggs tend to give larger values of the light CP-even Higgs mass, M_h, in the region of large stop masses than previous predictions that were based on a fixed-order Feynman-diagrammatic result, though the differences are generally consistent with the previous estimates of theoretical uncertainties. We re-analyse the parameter spaces of the CMSSM, NUHM1 and NUHM2, taking into account also the constraints from CMS and LHCb measurements of mathrm{BR}(B_s rightarrow mu ^+mu ^-)and ATLAS searches for /!!!E_T events using 20/fb of LHC data at 8 TeV. Within the CMSSM, the Higgs mass constraint disfavours {tan beta }lesssim 10, though not in the NUHM1 or NUHM2.

Decoupling of the right-handed neutrino contribution to the Higgs mass in supersymmetric models

Recently, it has been argued that in the supersymmetric extension of the seesaw-extended Standard Model, heavy right-handed neutrinos and sneutrinos may give corrections as large as a few GeV to the mass of the lightest neutral CP-even Higgs boson, even if the soft supersymmetry-breaking parameters are of order the electroweak scale. The presence of such large corrections would render precise Higgs masses incalculable from measurable low-energy parameters. We show that this is not the case: decoupling is preserved in the appropriate sense and right-handed (s)neutrinos, if they exist, have negligible impact on the physical Higgs masses.

Top polarization and stop mixing from boosted jet substructure

Top polarization is an important probe of new physics that couples to the top sector, and which may be discovered at the 14 TeV LHC. Taking the example of the MSSM, we argue that top polarization measurements can put a constraint on the soft supersymmetry breaking parameter A t . In light of the recent discovery of a Higgs-like boson of mass ∼ 125 GeV, a large A t is a prediction of many supersymmetric models. To this end, we develop a detector level analysis methodology for extracting polarization information from hadronic tops using boosted jet substructure. We show that with 100 fb−1 of data, left and right 600 GeV stops can be distinguished to 4σ, and 800 GeV stops can be distinguished to 3σ.

On the distribution of stable de Sitter vacua

The possible existence of (meta-) stable de Sitter vacua in string theory is of fundamental importance. So far, there are no fully stable solutions where all effects are under perturbative control. In this paper we investigate the presence of stable de Sitter vacua in type II string theory with non-geometric fluxes. We introduce a systematic method for solving the equations of motion at the origin of moduli space, by expressing the fluxes in terms of the supersymmetry breaking parameters. As a particular example, we revisit the geometric type IIA compactifications, and argue that non-geometric fluxes are necessary to have (isotropically) stable de Sitter solutions. We also analyse a class of type II compactifications with non-geometric fluxes, and study the distribution of (isotropically) stable de Sitter points in the parameter space. We do this through a random scan as well as through a complementary analysis of two-dimensional slices of the parameter space. We find that the (isotropically) stable de Sitter vacua are surprisingly rare, and organise themselves into thin sheets at small values of the cosmological constant.

TeV scale mirage mediation in NMSSM

We study the next-to-minimal supersymmetric standard model. We consider soft supersymmetry breaking parameters, which are induced by the mirage mediation mechanism of supersymmetry breaking. We concentrate on the mirage mediation, where the so-called mirage scale is the TeV scale. In this scenario, we can realize the up-type Higgs soft mass of O(200) GeV, while other masses such as gaugino masses and stop masses are heavy such as 1 TeV or more. Cancellation between the effective \mu-term and the down-type Higgs soft mass ameliorates the fine-tuning in the electroweak symmetry breaking even for \mu=O(500) GeV. The mixing between the doublet and singlet Higgs bosons is suppressed by (\lambda/\kappa)/tan\beta. Then the lightest doublet Higgs mass naturally reaches 125 GeV lifted by the new quartic coupling. The higgsino and singlino are light and their linear combination is the lightest superparticle.

SuSeFLAV 1.2: Program for supersymmetric mass spectra with seesaw mechanism and rare lepton flavor violating decays

Accurate supersymmetric spectra are required to confront data from direct and indirect searches of supersymmetry. SuSeFLAV11http://cts.iisc.ernet.in/Suseflav/main.html. is a numerical tool capable of computing supersymmetric spectra precisely for various supersymmetric breaking scenarios applicable even in the presence of flavor violation. The program solves MSSM RGEs with complete 3×3 flavor mixing at 2-loop level and one loop finite threshold corrections to all MSSM parameters by incorporating radiative electroweak symmetry breaking conditions. The program also incorporates the Type-I seesaw mechanism with three massive right handed neutrinos at user defined mass scales and mixing. It also computes branching ratios of flavor violating processes such as lj→liγ, lj→3li, b→sγ and supersymmetric contributions to flavor conserving quantities such as (gμ−2). A large choice of executables suitable for various operations of the program are provided. Program summaryProgram title: SuSeFLAVCatalogue identifier: AEOD_v1_0Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEOD_v1_0.htmlProgram obtainable from: CPC Program Library, Queen’s University, Belfast, N. IrelandLicensing provisions: GNU General Public LicenseNo. of lines in distributed program, including test data, etc.: 76552No. of bytes in distributed program, including test data, etc.: 582787Distribution format: tar.gzProgramming language: Fortran 95.Computer: Personal Computer, Work-Station.Operating system: Linux, Unix.Classification: 11.6.Nature of problem:Determination of masses and mixing of supersymmetric particles within the context of MSSM with conserved R-parity with and without the presence of Type-I seesaw. Inter-generational mixing is considered while calculating the mass spectrum. Supersymmetry breaking parameters are taken as inputs at a high scale specified by the mechanism of supersymmetry breaking. RG equations including full inter-generational mixing are then used to evolve these parameters up to the electroweak breaking scale. The low energy supersymmetric spectrum is calculated at the scale where successful radiative electro-weak symmetry breaking occurs. At weak scale standard model fermion masses, gauge couplings are determined including the supersymmetric radiative corrections. Once the spectrum is computed, the program proceeds to various lepton flavor violating observables (e.g., BR(μ→eγ), BR(τ→μγ) etc.) at the weak scale.Solution method:Two loop RGEs with full 3×3 flavor mixing for all supersymmetry breaking parameters are used to compute the low energy supersymmetric mass spectrum. An adaptive step size Runge–Kutta method is used to solve the RGEs numerically between the high scale and the electroweak breaking scale. Iterative procedure is employed to get the consistent radiative electroweak symmetry breaking condition. The masses of the supersymmetric particles are computed at 1-loop order. The third generation SM particles and the gauge couplings are evaluated at the 1-loop order including supersymmetric corrections. A further iteration of the full program is employed such that the SM masses and couplings are consistent with the supersymmetric particle spectrum.Additional comments:Several executables are presented for the user.Running time:0.2 s on a Intel(R) Core(TM) i5 CPU 650 with 3.20 GHz.

Wilson lines and a canonical basis of SU(4) heterotic standard models

The spontaneous breaking of SU(4) heterotic standard models by Z_3 x Z_3 Wilson lines to the MSSM with three right-handed neutrino supermultiplets and gauge group SU(3)_C x SU(2)_L x U(1) x U(1) is explored. The two-dimensional subspace of the Spin(10) Lie algebra that commutes with su(3)_C + su(2)_L is analyzed. It is shown that there is a unique basis for which the initial soft supersymmetry breaking parameters are uncorrelated and for which the U(1) x U(1) field strengths have no kinetic mixing at any scale. If the Wilson lines "turn on" at different scales, there is an intermediate regime with either a left-right or a Pati-Salam type model. We compute their spectra directly from string theory, and adjust the associated mass parameter so that all gauge parameters exactly unify. A detailed analysis of the running gauge couplings and soft gaugino masses is presented.

Phenomenological MSSM interpretation of LHC results using rernormalization group invariants

The LHC has started to constrain supersymmetry-breaking parameters by setting bounds on possible colored particles at the weak scale. Moreover, constraints from Higgs physics, flavor physics, the anomalous magnetic moment of the muon, as well as from searches at LEP and the Tevatron have set additional bounds on these parameters. Renormalization group invariants provide a very useful way of representing the allowed parameter space by making a direct connection with the values of these parameters at the messenger scale. Using a general approach, based on the phenomenological minimal supersymmetric standard model parametrization of the soft supersymmetry-breaking parameters, we analyze the current experimental constraints to determine the probability distributions for the renormalization group invariants. As examples of their application, we use these distributions to analyze the question of gaugino mass unification and to probabilistically determine the parameters of general and minimal gauge mediation with arbitrary Higgs mass parameters at the messenger scale.

Supersymmetric seesaw inflation

Supersymmetric Unified theories which incorporate a renormalizable Type I seesaw mechanism for small neutrino masses can also provide slow roll inflection point inflation along a flat direction associated with a gauge invariant combination of the Higgs, slepton and right handed sneutrino superfields. Inflationary parameters are related to the Majorana and Dirac couplings responsible for neutrino masses with the scale of inflation set by a right-handed neutrino mass $M_{\nu^c} \sim 10^6-10^{12}$ GeV. Tuning of the neutrino Dirac and Majorana superpotential couplings and soft Susy breaking parameters is required to enforce flatness of the inflationary potential. In contrast to previous inflection point inflation models the cubic term is dominantly derived from superpotential couplings rather than soft A-terms. Thus since $M_{\nu^c}>>M_{Susy}$ the tuning condition is almost independent of the soft supersymmetry breaking parameters and therefore more stable. The required fine tuning is also less stringent than for Minimal SUSY Standard Model (MSSM) inflation or Dirac neutrino 'A-term" inflation scenarios due to the much larger value of the inflaton mass. Reheating proceeds via `instant preheating' which rapidly dumps all the inflaton energy into a MSSM mode radiation bath giving a high reheat temperature $T_{rh} \approx M_{\nu^c}^{3/4}\, 10^{6}$ GeV $\sim 10^{11}- 10^{15} $ GeV. Thus our scenario requires large gravitino mass $> 50 $ TeV to avoid a gravitino problem. The `instant preheating' and Higgs component of the inflaton also imply a `non-thermal' contribution to Leptogenesis due to facilitated production of right handed neutrinos during inflaton decay. We derive the tuning conditions for the scenario to work in the realistic New Minimal Supersymmetric SO(10) GUT and show that they can be satisfied by realistic fits.

Yukawa coupling unification inSO(10)with positiveμand a heavier gluino

The $t\mathrm{\text{\ensuremath{-}}}b\mathrm{\text{\ensuremath{-}}}\ensuremath{\tau}$ unification with positive Higgs mass parameter $\ensuremath{\mu}$ in the minimal supersymmetric standard model prefers ``just so'' Higgs splitting and a light gluino $\ensuremath{\lesssim}500\text{ }\text{ }\mathrm{GeV}$ which appears to be ruled out by the recent LHC searches. We reanalyze constraints on soft supersymmetry breaking parameters in this scenario, allowing independent splittings among squarks and Higgs doublets at the grand unification scale, and show that it is possible to obtain $t\mathrm{\text{\ensuremath{-}}}b\mathrm{\text{\ensuremath{-}}}\ensuremath{\tau}$ unification and satisfy experimental constraints on gluino mass without raising supersymmetry breaking scale to very high value $\ensuremath{\sim}20\text{ }\text{ }\mathrm{TeV}$. We discuss the origin of independent squark and Higgs splittings in realistic $SO(10)$ models. Just so Higgs splitting can be induced without significantly affecting the $t\mathrm{\text{\ensuremath{-}}}b\mathrm{\text{\ensuremath{-}}}\ensuremath{\tau}$ unification in $SO(10)$ models containing Higgs fields transforming as $10+\overline{126}+126+210$. This splitting arises in the presence of nonuniversal boundary conditions from mixing between 10 and other Higgs fields. Similarly, if additional matter fields are introduced then their mixing with the matter multiplet 16 is shown to generate the squark splitting required to raise the gluino mass within the $t\mathrm{\text{\ensuremath{-}}}b\mathrm{\text{\ensuremath{-}}}\ensuremath{\tau}$ unified models with positive $\ensuremath{\mu}$.

Phenomenology of anomaly-mediated supersymmetry-breaking scenarios with nonminimal flavor violation

In minimal anomaly-mediated supersymmetry-breaking models, tachyonic sleptons are avoided by introducing a common scalar mass similar to the one introduced in minimal supergravity. This may lead to nonminimal flavor-violating interactions, e.g., in the squark sector. In this paper, we analyze the viable anomaly-mediated supersymmetry-breaking parameter space in the light of the latest limits on low-energy observables and LHC searches, complete our analytical calculations of flavor-violating supersymmetric particle production at hadron colliders with those related to gluino production, and study the phenomenological consequences of nonminimal flavor violation in anomaly-mediated supersymmetry-breaking scenarios at the LHC. Related cosmological aspects are also briefly discussed.

Light stau phenomenology and the Higgs γγ rate

Abstract Recently, an excess of events consistent with a Higgs boson with mass of about 125 GeV was reported by the CMS and ATLAS experiments. This Higgs boson mass is consistent with the values that may be obtained in minimal supersymmetric extensions of the Standard Model (SM), with both stop masses less than a TeV and large mixing. The apparently enhanced photon production rate associated with this potential Higgs signal may be the result of light staus with large mixing. Large stau mixing and large coupling of the staus to the SM-like Higgs boson may be obtained for large values of tan β and moderate to large values of the Higgsino mass parameter, μ. We study the phenomenological properties of this scenario, including precision electroweak data, the muon anomalous magnetic moment, Dark Matter, and the evolution of the soft supersymmetry-breaking parameters to high energies. We also analyze the possible collider signatures of light third generation sleptons and demonstrate that it is possible to find evidence of their production at the 8 TeV and the 14 TeV LHC. The most promising channel is stau and tau sneutrino associated production, with the sneutrino decaying into a W boson plus a light stau.

Flavor violating processes with sgoldstino pair production

In supersymmetric extensions of the Standard Model of particle physics (SM), goldstino superpartners --- scalar and pseudoscalar sgoldstinos --- can be light enough for emerging in decays of SM particles. Sgoldstino interaction with SM fields is suppressed by the scale of supersymmetry breaking in the whole theory. Hence, searches for sgoldstinos give an opportunity to probe the underlying mechanism of supersymmetry breaking. Sgoldstino couplings to SM fields are proportional to the supersymmetry breaking parameters --- MSSM soft terms --- and therefore can lead to flavor violating processes in quark and lepton sectors. We consider flavor violating processes involving sgoldstino pair production which are driven by sgoldstino couplings proportional to squark and slepton soft mass terms, \tilde{m^2_{LL}} and \tilde{m^2_{RR}}. We find that present limits on off-diagonal entries in squark and slepton squared mass matrices allow t-, b-, c-quark and \tau-lepton decays at levels available for study with existing data (BaBar, Belle, CLEOc) and in ongoing experiments (LHCb, CMS, ATLAS). In particular, we obtain the following branching ratios Br(t--> c SP)\lesssim 10^{-7}, Br(\tau--> \mu SP) \lesssim 10^{-7}, Br(B_s--> SP) \lesssim 10^{-4}, Br(B--> K^{(*)} SP) \lesssim 10^{-4}, Br(D--> SP) \lesssim 10^{-7} with sgoldstino subsequent decays into kinematically allowed pairs of SM particles \gamma\gamma, e^+e^-, \mu^+\mu^-, etc. Remarkably, the prominent signature of sgoldstino pair production is two muon pairs with pair momenta peaked at sgoldstino masses.

Neutralino-sbottom coannihilation in SU(5)

We identify within the SU(5) framework the minimum number of soft supersymmetry breaking parameters which can yield a bottom squrak (sbottom) as the next to lightest supersymmetric particle. We focus in particular on the neutralino-sbottom coannihilation scenario which gives rise to the desired neutralino dark matter relic density. We find solutions in which the sbottom mass is greater than or of order 210 GeV, while the gluino and the first two family squarks are heavier than 1 TeV. Some benchmark points which can be tested at the LHC are presented.

Supersymmetric multi-Higgs doublet model with nonlinear electroweak symmetry breaking

The electroweak symmetry is nonlinearly realized in an extension of the minimal supersymmetric standard model (MSSM) through an additional pair of constrained Higgs doublet superfields. The superpotential couplings of this constrained Higgs doublet pair to the MSSM Higgs doublet pair catalyze their vacuum expectation values. The Higgs and Higgsino-gaugino mass spectrum is presented for several choices of supersymmetry breaking and Higgs superpotential mass parameters. The additional vacuum expectation values provided by the constrained fields can produce a phenomenology quite different than that of the MSSM.

Implications of a 125 GeV Higgs for supersymmetric models

Preliminary results of the search for a Standard Model like Higgs boson at the LHC with 5 fb−1 data have just been presented by the ATLAS and CMS Collaborations and an excess of events at a mass of ≈125 GeV has been reported. If this excess of events is confirmed by further searches with more data, it will have extremely important consequences in the context of supersymmetric extensions of the Standard Model and, in particular the minimal one, the MSSM. We show that for a standard-like Higgs boson with a mass 123<Mh<127 GeV, several unconstrained or constrained (i.e. with soft supersymmetry-breaking parameters unified at the high scale) MSSM scenarios would be excluded, while the parameters of some other scenarios would be severely restricted. Examples of constrained MSSM scenarios which would be disfavoured as they predict a too light Higgs particle are the minimal anomaly and gauge mediated supersymmetry-breaking models. The gravity mediated constrained MSSM would still be viable, provided the scalar top quarks are heavy and their trilinear coupling large. Significant areas of the parameter space of models with heavy supersymmetric particles, such as split or high-scale supersymmetry, could also be excluded as, in turn, they generally predict a too heavy Higgs particle.