Gauge-mediated SUSY Breaking Models Research Articles

Charms of strongly interacting conformal gauge mediation

By extending a previously proposed conformal gauge mediation model, we construct a gauge-mediated SUSY breaking (GMSB) model where a SUSY-breaking scale, a messenger mass, the μ-parameter and the gravitino mass in a minimal supersymmetric (SUSY) Standard Model (MSSM) are all explained by a single mass scale, a R-symmetry breaking scale. We focus on a low scale SUSY-breaking scenario with the gravitino mass m3/2 = mathcal{O}(1)mathrm{eV} , which is free from the cosmological gravitino problem and relaxes the fine-tuning of the cosmological constant. Both the messenger and SUSY-breaking sectors are subject to a hidden strong dynamics with the conformality above the messenger mass threshold (and hence the name of the model “strongly interacting conformal gauge mediation”). In our model, the Higgs B-term is suppressed and a large tan β is predicted, resulting in the relatively light second CP-even Higgs and the CP-odd Higgs with a sizable production cross section. These Higgs bosons can be tested at future LHC experiments.

New type of charged Q -ball dark matter in gauge mediated SUSY breaking models

We examined the viability of a new type of charged $Q$-ball dark matter scenario. We considered the case where the relics can be treated as ordinary ions, to which we applied the observational constraint from the MICA experiment, where no trail of heavy ionlike object is observed in $1{0}^{9}$ year-old ancient muscovite mica. We have found that the allowed parameter region exists but is smaller than the neutral $Q$-ball dark matter case. We have also discussed whether our scenario is actually consistent with Affleck-Dine mechanism.

Can thermal inflation be consistent with baryogenesis in gauge-mediated SUSY breaking models?

Thermal inflation is an attractive idea to dilute cosmic density of unwanted particles such as moduli fields which cause cosmological difficulties. However, it also dilutes preexisting baryon asymmetry and some viable baryogenesis is necessary for a cosmologically consistent scenario. We investigate whether the Affleck-Dine mechanism can produce baryon asymmetry enough to survive after the dilution in gauge-mediated SUSY breaking models. Flat directions except for $LH_u$ flat direction cannot provide such huge baryon number because of Q-ball formation. We show that although the $LH_u$ flat direction is special in terms of having $\mu$-term which prevents Q-ball formation, it cannot explain the observed baryon asymmetry either.

Long-Lived Gluinos and Stable Axinos.

In this Letter we present a novel version of "long-lived" gluinos in supersymmetric models with the gluino lightest ordinary supersymmetric particle (LOSP) and the axino lightest supersymmetric particle. Within certain ranges of the axion decay constant f_{a}<1×10^{10} GeV, the gluino mass bounds are reduced to less than 1000GeV. The best limits can be obtained by looking for decaying R hadrons in the detector where the gluino decays to a gluon and axino in the calorimeters. Supersymmetry (SUSY) models with a gluino LOSP can occur over a significant region of parameter space in either mirage mediation or general gauge-mediated SUSY breaking models. The gluino LOSP is not constrained by cosmology, but in this scenario the axion or axino may be a good dark matter candidate.

ChargedQ-balls in gauge mediated SUSY breaking models

It is known that after Affleck-Dine baryogenesis, spatial inhomogeneities of Affleck-Dine field grow into non-topological solitons called Q-balls. In gauge mediated SUSY breaking models, sufficiently large Q-balls with baryon charge are stable while Q-balls with lepton charge can always decay into leptons. For a Q-ball that carries nonzero $B$ and $L$ charges, the difference between the baryonic component and the leptonic component in decay rate may induce nonzero electric charge on the Q-ball. This implies that charged Q-ball, also called gauged Q-ball, may emerge in our universe. In this paper, we investigate two complex scalar fields, a baryonic scalar field and a leptonic one, in an Abelian gauge theory. We find stable solutions of gauged Q-balls for different baryon and lepton charges. Those solutions shows that a Coulomb potential arises and the Q-ball becomes electrically charged as expected. It is energetically favored that some amount of leptonic component decays, but there is an upper bound on its amount due to the Coulomb force. The baryonic decay also becomes possible by virtue of electrical repulsion and we find the condition to suppress it so that the charged Q-balls can survive in the universe.

Search for supersymmetry in events with large missing transverse momentum, jets, and at least one tau lepton in 20 fb−1 of s $$ \sqrt{s} $$ = 8 TeV proton-proton collision data with the ATLAS detector

A search for supersymmetry (SUSY) in events with large missing transverse momentum, jets, at least one hadronically decaying tau lepton and zero or one additional light leptons (electron/muon), has been performed using 20.3 fb$^{-1}$ of proton-proton collision data at $\sqrt{s} = 8$ TeV recorded with the ATLAS detector at the Large Hadron Collider. No excess above the Standard Model background expectation is observed in the various signal regions and 95% confidence level upper limits on the visible cross section for new phenomena are set. The results of the analysis are interpreted in several SUSY scenarios, significantly extending previous limits obtained in the same final states. In the framework of minimal gauge-mediated SUSY breaking models, values of the SUSY breaking scale $\Lambda$ below 63 TeV are excluded, independently of tan$\beta$. Exclusion limits are also derived for an mSUGRA/CMSSM model, in both the R-parity-conserving and R-parity-violating case. A further interpretation is presented in a framework of natural gauge mediation, in which the gluino is assumed to be the only light coloured sparticle and gluino masses below 1090 GeV are excluded.

Searches for heavy long-lived sleptons and R-hadrons with the ATLAS detector in pp collisions at [formula omitted

A search for long-lived particles is performed using a data sample of 4.7 fb−1 from proton–proton collisions at a centre-of-mass energy s=7 TeV collected by the ATLAS detector at the LHC. No excess is observed above the estimated background and lower limits, at 95% confidence level, are set on the mass of the long-lived particles in different scenarios, based on their possible interactions in the inner detector, the calorimeters and the muon spectrometer. Long-lived staus in gauge-mediated SUSY-breaking models are excluded up to a mass of 300 GeV for tanβ=5–20. Directly produced long-lived sleptons are excluded up to a mass of 278 GeV. R-hadrons, composites of gluino (stop, sbottom) and light quarks, are excluded up to a mass of 985 GeV (683 GeV, 612 GeV) when using a generic interaction model. Additionally two sets of limits on R-hadrons are obtained that are less sensitive to the interaction model for R-hadrons. One set of limits is obtained using only the inner detector and calorimeter observables, and a second set of limits is obtained based on the inner detector alone.

Searches for heavy long-lived sleptons andR-hadrons with the ATLAS detector

A search for long-lived particles is performed using a data sample of 4.7 fb−1 from proton-proton collisions at a centre-of-mass energy √s = 7 TeV collected by the ATLAS detector at the LHC. No excess is observed above the estimated background and lower limits, at 95% confidence level, are set on the mass of the long-lived particles in different scenarios, based on their possible interactions in the inner detector, the calorimeters and the muon spectrometer. Long-lived staus in gauge-mediated SUSY-breaking models are excluded up to a mass of 300 GeV for tan β = 5 − 20. Directly produced long-lived sleptons are excluded up to a mass of 278 GeV. R -hadrons, composites of gluino (stop, sbottom) and light quarks, are excluded up to a mass of 985 GeV (683 GeV, 612 GeV) when using a generic interaction model. Additionally two sets of limits on R -hadrons are obtained that are less sensitive to the interaction model for R -hadrons. One set of limits is obtained using only the inner detector and calorimeter observables, and a second set of limits is obtained based on the inner detector alone. The full paper can be found in [1].

Peccei-Quinn extended gauge-mediation model with vector-like matter and 125 GeV Higgs

We construct a gauge-mediated SUSY breaking model with vector-like matters combined with the Peccei-Quinn mechanism to solve the strong CP problem. The Peccei-Quinn symmetry plays an essential role for generating sizable masses for the vector-like matters and the $\mu$-term without introducing dangerous CP angle. The model naturally explains both the 125GeV Higgs mass and the muon anomalous magnetic moment. The stabilization of the Peccei-Quinn scalar and the cosmology of the saxion and axino are also discussed.

Search for supersymmetry in events with large missing transverse momentum, jets, and at least one tau lepton in 7 TeV proton-proton collision data with the ATLAS detector

A search for supersymmetry (SUSY) in events with large missing transverse momentum, jets, and at least one hadronically decaying tau lepton, with zero or one additional light lepton (e/mu), has been performed using 4.7 fb-1 of proton-proton collision data at sqrt(s) = 7 TeV recorded with the ATLAS detector at the Large Hadron Collider. No excess above the Standard Model background expectation is observed and a 95% confidence level visible cross-section upper limit for new phenomena is set. In the framework of gauge-mediated SUSY-breaking models, lower limits on the mass scale Lambda are set at 54 TeV in the regions where the stau is the next-to-lightest SUSY particle (tan(beta) > 20). These limits provide the most stringent tests to date of GMSB models in a large part of the parameter space considered.

Search forZγevents with large missing transverse energy inpp¯collisions ats=1.96 TeV

We present the first search for supersymmetry (SUSY) in Zgamma final states with large missing transverse energy using data corresponding to an integrated luminosity of 6.2 fb-1 collected with the D0 experiment in ppbar collisions at sqrt(s)=1.96 TeV. This signature is predicted in gauge-mediated SUSY-breaking models, where the lightest neutralino is the next-to-lightest supersymmetric particle (NLSP) and is produced in pairs, possibly through decay from heavier supersymmetric particles. The NLSP can decay either to a Z boson or a photon and an associated gravitino that escapes detection. We exclude this model at the 95% C.L. for SUSY breaking scales of Lambda < 87 TeV, corresponding to neutralino masses of < 151 GeV.

Higgs mass, muong−2, and LHC prospects in gauge mediation models with vectorlike matters

Recently the ATLAS and CMS collaborations presented preliminary results of Standard Model Higgs searches and reported excesses of events for a Higgs boson at 124-126 GeV. Such a Higgs mass can be naturally realized, simultaneously explaining the muon g-2 anomaly, in gauge-mediated SUSY breaking models with extra vector-like matters. Upper bounds are obtained on the gluino mass, m_{\tilde g}\lesssim 1.2 (1.8) TeV, and on the extra vector-like quark mass, M_{Q'} \lesssim 1.0 (1.8) GeV, in the parameter region where the Higgs boson mass is 124-126 GeV and the muon g-2 is consistent with the experimental value at the 1 sigma (2 sigma) level. The LHC prospects are explored in the parameter region. It is found that some of the regions are already excluded by the LHC, and most of the parameter space is expected to be covered at \sqrt{s} = 14 TeV. A study on the extra vector-like quarks, especially current bounds on their masses and prospects for future searches, is also included.

Higgs mass and muon anomalous magnetic moment in the U(1)- extended MSSM

We study phenomenological aspects of the minimal SUSY standard model with extra U(1) gauge symmetry. We find that the lightest Higgs boson mass can be increased up to 125 GeV without introducing a large SUSY scale or large $A$-terms, in the frameworks of the CMSSM and gauge-mediated SUSY-breaking models. This scenario can simultaneously explain the discrepancy of the muon anomalous magnetic moment (muon $g\ensuremath{-}2$) at the $1\ensuremath{\sigma}$ level in both of the frameworks, U(1)-extended CMSSM/GMSB models. In the CMSSM case, the dark matter abundance can also be explained.

NMSSM in gauge-mediated SUSY breaking without domain wall problem

A problem of the gauge-mediated SUSY breaking model is its difficulty to generate a natural value of μ/Bμ, while the NMSSM is a natural framework to solve the μ/Bμ-problem. The NMSSM in gauge-mediated SUSY breaking in its original form does not work well since the singlet field cannot develop a desired vacuum expectation value. It also suffers from the cosmological domain wall problem. We study an extension of the model to include additional vector-like matter, which is charged under the hidden QCD. It is shown that this simple extension solves both the problems. We study phenomenological and cosmological implications of this extended models. The lightest Higgs mass can be as large as 130–140 GeV for some model points.

Higgs mass and muon anomalous magnetic moment in supersymmetric models with vectorlike matters

We study the muon anomalous magnetic moment (muon g-2) and the Higgs boson mass in a simple extension of the minimal supersymmetric (SUSY) Standard Model with extra vector-like matters, in the frameworks of gauge mediated SUSY breaking (GMSB) models and gravity mediation (mSUGRA) models. It is shown that the deviation of the muon g-2 and a relatively heavy Higgs boson can be simultaneously explained in large tan-beta region. (i) In GMSB models, the Higgs mass can be more than 135 GeV (130 GeV) in the region where muon g-2 is consistent with the experimental value at the 2 sigma (1 sigma) level, while maintaining the perturbative coupling unification. (ii) In the case of mSUGRA models with universal soft masses, the Higgs mass can be as large as about 130 GeV when muon g-2 is consistent with the experimental value at the 2 sigma level. In both cases, the Higgs mass can be above 140 GeV if the g-2 constraint is not imposed.

SOFT LEPTOGENESIS AND GRAVITINO DARK MATTER IN GAUGE MEDIATION

In gauge mediated SUSY breaking models, the gravitino is generally the lightest SUSY particle and can be a candidate for a dark matter. However the viable abundance of the gravitino requires rather low reheating temparature. With this low reheating temparature, it is difficult to explain the baryon asymmetry of the universe with thermal leptogenesis. We consider the extended scenario of the gauge mediation, which generates A-terms. In this extended scenario, soft leptogenesis works successfully with the low reheating temperature. Therefore we can explain the baryon asymmetry and gravitino dark matter simultaneously.

WIMP dark matter in gauge-mediated SUSY breaking models and its phenomenology

We propose an extended version of the gauge-mediated SUSY breaking models where extra SU(2)L doublets and singlet field are introduced. These fields are assumed to be parity-odd under an additional matter parity. In this model, the lightest parity-odd particle among them would be dark matter in the Universe. In this Letter, we discuss direct detection of the dark matter and the collider signatures of the model.

SUPERNATURAL A-TERM INFLATION

Following Ref. 10, we explore the parameter space of the case when the supersymmetry (SUSY) breaking scale is lower, for example, in gauge mediated SUSY breaking model. During inflation, the form of the potential is V0 plus MSSM (or A-term ) inflation. We show that the model works for a wide range of the potential V0 with the soft SUSY breaking mass m ~ O(1) TeV. The implication to MSSM (or A-term) inflation is that the flat directions which is lifted by the non-renormalizable terms described by the superpotential [Formula: see text] with p = 4 and p = 5 are also suitable to be an inflaton field for λp = O(1) provided there is an additional false vacuum term V0 with appropriate magnitude. The flat directions correspond to p = 6 also works for [Formula: see text].

A lower bound on hadronic EDMs from CP violation in [formula omitted] mixing in SUSY alignment models

The SM predictions for CP violating effects in D meson systems are highly suppressed at the per mill level. Therefore, any experimental evidence for a sizable CP violation in D0–D¯0 mixing would unambiguously point towards a New Physics (NP) signal. Within supersymmetric scenarios, the popular alignment models can naturally account for large, non-standard effects in D0–D¯0 mixing. We demonstrate that, within alignment models, detectable CP violating effects in D0–D¯0 mixing would unambiguously imply a lower bound for the electric dipole moment (EDM) of hadronic systems, like the neutron EDM and the mercury EDM, in the reach of future experimental sensitivities. The simultaneous evidence of CP violation in D meson systems together with non-vanishing hadronic EDMs would strongly support the idea of SUSY alignment models and disfavour gauge-mediated SUSY breaking models, SUSY models with MFV and non-Abelian SUSY flavour models. As a byproduct of our analysis, we study the correlation between the time dependent CP asymmetry in decays to CP eigenstates Sf and the semileptonic asymmetry aSL both model independently and in SUSY alignment models.

A realistic extension of gauge-mediated SUSY-breaking model with superconformal hidden sector

The sequestering of supersymmetry (SUSY) breaking parameters, which is induced by superconformal hidden sector, is one of the solutions for the μ/Bμ problem in gauge-mediated SUSY-breaking scenario. However, it is found that the minimal messenger model does not derive the correct electroweak symmetry breaking. In this Letter we present a model which has the coupling of the messengers with the SO(10) GUT-symmetry breaking Higgs fields. The model is one of the realistic extensions of the gauge mediation model with superconformal hidden sector. It is shown that the extension is applicable for a broad range of conformality breaking scale.