Gauge-mediated Supersymmetry Breaking Research Articles

Searches for supersymmetry at CMS in final states with photons

Four searches for supersymmetry at CMS in final states with photons are discussed in this article. The data analyzed corresponds to up to 19.7fb-1 and was recorded at centre-of-mass energies of 7 and 8 TeV by the CMS experiment. Searches in final states with photons are sensitive to various scenarios for physics beyond the standard model, especially gauge mediated supersymmetry breaking. To increase the sensitivity for various classes of models, four analyses with different selections and background estimation methods are performed. Wino-like neutralino mixing scenarios are probed in final states with at least one photon and jets, while final states with at least two photons are most sensitive to bino-like neutralino mixing scenarios. A higgsino-like neutralino scenario is studied by selecting two photons with an invariant mass close to the Higgs mass. While all of these analyses explore events with high missing transverse energy, a fourth analysis covers also final states with two photons and low missing transverse energy. No excess of data over the standard model expectation is observed, and upper limits on various signal cross sections are calculated.

Disappearing charged tracks in association with displaced leptons from supersymmetry

In this note we discuss a characteristic collider signature of models of gauge mediated supersymmetry breaking in which the selectron and smuon are mass-degenerate co-NLSP. In these models, all processes involving superpartners give rise to two NLSP selectrons or smuons, each of which subsequently decays to a nearly massless LSP gravitino and an electron or a muon. In a large region of the parameter space, the NLSPs travel macroscopic distances, of the order 0.1 – 1000 mm, before they decay. Hence, these models give rise to collider signatures involving charged tracks that end at vertices, which are inside the detector volume but displaced with respect to the original collision point, from which an electron or a muon is emitted. In order to probe this class of models we propose a search for disappearing charged tracks in association with displaced electrons or muons.

Low-scale gauge mediation with a 100 TeV gravitino

We propose a new framework of low-scale gauge-mediated supersymmetry (SUSY) breaking with a gravitino mass of O(100) TeV. The usual 4D gauge mediation models predict a light gravitino and suffer from cosmological problems. In our framework, a heavy gravitino in gauge mediation is realized with a flat extra-dimension, whose compactification scale is around the grand unified theory scale. Superparticle masses of the visible sector from gravity/anomaly mediation are suppressed, and they are purely generated by usual gauge mediation on the visible brane. Importantly, the Higgs Bmu-term vanishes at the leading order, which enables us to obtain the suitable mu-Bmu relation for the electroweak symmetry breaking. We discuss such models considering two possibilities of the SUSY breaking source: 1) Scherk-Schwarz SUSY breaking which we call Scherk-Schwarz Gauge Mediation and 2) gravitational SUSY breaking localized on a hidden brane. In the case 2), the cosmological moduli problem may be relaxed as well.

Axino dark matter and baryon number asymmetry production by the Q-ball decay in gauge mediation

We investigate the Q-ball decay into the axino dark matter in the gauge-mediated supersymmetry breaking. In our scenario, the Q ball decays mainly into nucleons and partially into axinos to account respectively for the baryon asymmetry and the dark matter of the universe. The Q ball decays well before the big bang nucleosynthesis so that it is not affected by the decay. We show the region of the parameters which realizes this scenario.

Search for supersymmetry in electroweak production with photons and large missing transverse energy in pp collisions at s=8TeV

Results are reported from a search for supersymmetry with gauge-mediated supersymmetry breaking in electroweak production. Final states with photons and large missing transverse energy (MET) were examined. The data sample was collected in pp collisions at sqrt(s) = 8 TeV with the CMS detector at the LHC and corresponds to 7.4 inverse femtobarns. The analysis focuses on scenarios in which the lightest neutralino has bino- or wino-like components, resulting in decays to photons and gravitinos, where the gravitinos escape undetected. The data were obtained using a specially designed trigger with dedicated low thresholds, providing good sensitivity to signatures with photons, MET, and low hadronic energy. No excess of events over the standard model expectation is observed. The results are interpreted using the model of general gauge mediation. With the wino mass fixed at 10 GeV above that of the bino, wino masses below 710 GeV are excluded at 95% confidence level. Constraints are also set in the context of two simplified models, for which the analysis sets the lowest cross section limits on the electroweak production of supersymmetric particles.

Revisiting R-invariant direct gauge mediation

We revisit a special model of gauge mediated supersymmetry breaking, the "R-invariant direct gauge mediation." We pay particular attention to whether the model is consistent with the minimal model of the \mu-term, i.e., a simple mass term of the Higgs doublets in the superpotential. Although the incompatibility is highlighted in view of the current experimental constraints on the superparticle masses and the observed Higgs boson mass, the minimal \mu-term can be consistent with the R-invariant gauge mediation model via a careful choice of model parameters. We derive an upper limit on the gluino mass from the observed Higgs boson mass. We also discuss whether the model can explain the 3\sigma excess of the Z+jets+$E_T^{\rm miss}$ events reported by the ATLAS Collaboration.

750 GeV diphoton resonance, 125 GeV Higgs and muon g− 2 anomaly in deflected anomaly mediation SUSY breaking scenarios

We propose to interpret the 750 GeV diphoton excess in deflected anomaly mediation supersymmetry breaking scenarios, which can naturally predict couplings between a singlet field and vector-like messengers. The CP-even scalar component (S) of the singlet field can serve as the 750 GeV resonance. The messenger scale, which is of order the gravitino scale, can be as light as F_\phi \sim {\cal O}(10) TeV when the messenger species N_F and the deflection parameter d are moderately large. Such messengers can induce the large loop decay process S \to \gamma\gamma. Our results show that such a scenario can successfully accommodate the 125 GeV Higgs boson, the 750 GeV diphoton excess and the muon g-2 without conflicting with the LHC constraints. We also comment on the possible explanations in the gauge mediation supersymmetry breaking scenario.

Reconciling the muong−2, a 125 GeV Higgs boson, and dark matter in gauge mediation models

We present a class of models in the framework of gauge mediation supersymmetry breaking where the standard model is supplemented by additional U(1) symmetry which acts only on the third generation fermions. The messenger fields carry non-trivial U(1) charge and are vector-like particles under this symmetry. This leads to additional contribution to the soft supersymmetry breaking mass terms for the third generation squarks and sleptons. In this framework we show that the muon g-2 anomaly, the observed 125 GeV Higgs boson mass and the detected relic dark matter abundance (gravitino in our case) can be simultaneously accommodated. The resolution of the muon g-2 anomaly, in particular, yields the result that the first two generation squark masses, as well the gluino mass, should be <~ 2.5 TeV, which will be tested at LHC14.

Search for photonic signatures of gauge-mediated supersymmetry in 8 TeVppcollisions with the ATLAS detector

A search is presented for photonic signatures motivated by generalised models of gauge-mediated supersymmetry breaking. This search makes use of $20.3{\rm fb}^{-1}$ of proton-proton collision data at $\sqrt{s}=8$ TeV recorded by the ATLAS detector at the LHC, and explores models dominated by both strong and electroweak production of supersymmetric partner states. Four experimental signatures incorporating an isolated photon and significant missing transverse momentum are explored. These signatures include events with an additional photon, lepton, $b$-quark jet, or jet activity not associated with any specific underlying quark flavor. No significant excess of events is observed above the Standard Model prediction and model-dependent 95% confidence-level exclusion limits are set.

Summary of the searches for squarks and gluinos using s = 8 $$ \sqrt{s}=8 $$ TeV pp collisions with the ATLAS experiment at the LHC

A summary is presented of ATLAS searches for gluinos and first- and second-generation squarks in final states containing jets and missing transverse momentum, with or without leptons or b-jets, in the $\sqrt{s}$ = 8 TeV data set collected at the Large Hadron Collider in 2012. This paper reports the results of new interpretations and statistical combinations of previously published analyses, as well as a new analysis. Since no significant excess of events over the Standard Model expectation is observed, the data are used to set limits in a variety of models. In all the considered simplified models that assume R-parity conservation, the limit on the gluino mass exceeds 1150 GeV at 95% confidence level, for an LSP mass smaller than 100 GeV. Furthermore, exclusion limits are set for left-handed squarks in a phenomenological MSSM model, a minimal Supergravity/Constrained MSSM model, R-parity-violation scenarios, a minimal gauge-mediated supersymmetry breaking model, a natural gauge mediation model, a non-universal Higgs mass model with gaugino mediation and a minimal model of universal extra dimensions.

Search for supersymmetry in events with a photon, a lepton, and missing transverse momentum in pp collisions at s=8 TeV

A search for supersymmetry involving events with at least one photon, one electron or muon, and large missing transverse momentum has been performed by the CMS experiment. The data sample corresponds to an integrated luminosity of 19.7 inverse femtobarns of pp collisions at sqrt(s) = 8 TeV, produced at the CERN LHC. No excess of events is observed beyond expectations from standard model processes. The result of the search is interpreted in the context of a general model of gauge-mediated supersymmetry breaking, where the charged and neutral winos are the next-to-lightest supersymmetric particles. Within this model, winos with a mass up to 360 GeV are excluded at the 95% confidence level. Two simplified models inspired by gauge-mediated supersymmetry breaking are also examined, and used to derive upper limits on the production cross sections of specific supersymmetric processes.

GMSB with light stops

Gauge mediated supersymmetry breaking (GMSB) is an elegant mechanism to transmit supersymmetry breaking from the hidden to the MSSM observable sector, which solves the supersymmetric avor problem. However the smallness of the generated stop mixing requires superheavy stops to reproduce the experimental value of the Higgs mass. A possible way out is to extend the MSSM Higgs sector with singlets and/or triplets providing extra tree-level corrections to the Higgs mass. Singlets will not get any soft mass from GMSB and triplets will contribute to the parameter which could be an issue. In this paper we explore the second possibility by introducing extra supersymmetric triplets with hypercharges Y = (0; 1), with a tree-level custodial SU(2)L SU(2)R global symmetry in the Higgs sector protecting the parameter: a supersymmetric generalization of the Georgi-Machacek model, dubbed as supersymmetric custodial triplet model (SCTM). The renormalization group running from the messenger to the electroweak scale mildly breaks the custodial symmetry. We will present realistic low-scale scenarios (with the NLSP being a Bino-like neutralino or the right-handed stau) based on general (non-minimal) gauge mediation and consistent with all present experimental data. Their main features are: i) Light ( 1 TeV) stops; ii) Exotic couplings (H W Z and H W W ) absent in the MSSM and proportional to the triplets VEV, v ; and, iii) A possible (measurable) universality breaking of the Higgs couplings WZ = rWW=rZZ6 1.

Focus point gauge mediation with incomplete adjoint messengers and gauge coupling unification

As the mass limits on supersymmetric particles are gradually pushed to higher values due to their continuing non-observation at the CERN LHC, looking for focus point regions in the supersymmetric parameter space, which shows considerably reduced fine-tuning, is increasingly more important than ever. We explore this in the context of gauge mediated supersymmetry breaking with messengers transforming in the adjoint representation of the gauge group, namely, octet of color SU(3) and triplet of weak SU(2). A distinctive feature of this scenario is that the focus point is achieved by fixing a single combination of parameters in the messenger sector, which is invariant under the renormalization group evolution. Because of this invariance, the focus point behavior is well under control once the relevant parameters are fixed by a more fundamental theory. The observed Higgs boson mass is explained with a relatively mild fine-tuning Δ=60–150. Interestingly, even in the presence of incomplete messenger multiplets of the SU(5) GUT group, the gauge couplings still unify perfectly, but at a scale which is one or two orders of magnitude above the conventional GUT scale. Because of this larger unification scale, the colored Higgs multiplets become too heavy to trigger proton decay at a rate larger than the experimentally allowed limit.

Yukawa unification and sparticle spectroscopy in gauge mediation models

We explore the implications of t-b-tau (and b-tau) Yukawa coupling unification condition on the fundamental parameter space and sparticle spectroscopy in the minimal gauge mediated supersymmetry breaking (mGMSB) model. We find that this scenario prefers values of the CP-odd Higgs mass m_A > 1 TeV, with all colored sparticle masses above 3 TeV. These predictions will be hard to test at LHC13 but they may be testable at HE-LHC 33 TeV or a 100 TeV collider. Both t-b-tau and b-tau Yukawa coupling unifications prefer a relatively light gravitino with mass < 30 eV, which makes it a candidate hot dark matter particle. However, it cannot account for more than 15 % of the observed dark matter density.

IceCube potential for detecting Q-ball dark matter in gauge mediation

We study |$Q$|-ball dark matter in gauge-mediated supersymmetry breaking, and seek the possibility of detection in the IceCube experiment. We find that the |$Q$| balls would be the dark matter in the parameter region different from that for gravitino dark matter. In particular, the |$Q$| ball is a good dark matter candidate for low reheating temperature, which may be suitable for the Affleck–Dine baryogenesis and|$/$|or nonthermal leptogenesis. Dark matter |$Q$| balls are detectable by IceCube-like experiments in the future, which is a peculiar feature compared to the case of gravitino dark matter.

Anatomy of new SUSY breaking holographic RG flows

We find and thoroughly study new supergravity domain wall solutions which are holographic realizations of supersymmetry breaking strongly coupled gauge theories. We set ourselves in an N=2 gauged supergravity with a minimal content in order to reproduce a dual N=1 effective SCFT which has a U(1)_R symmetry, a chiral operator whose components are responsible for triggering the RG flow, and an additional U(1)_F symmetry. We present a full three dimensional parameter space of solutions, which generically break supersymmetry. Some known solutions are recovered for specific sets of values of the parameters, with the new solutions interpolating between them. The generic backgrounds being singular, we provide a stability test of their dual theories by showing that there are no tachyonic resonances in the two point correlators. We compute the latter by holographic renormalization. We also carefully analyze the appearance of massless modes, such as the dilaton and the R axion, when the respective symmetries are spontaneously broken, and their lifting when the breaking is explicit. We further comment on the application of such class of backgrounds as archetypes of strongly coupled hidden sectors for gauge mediation of supersymmetry breaking. In particular, we show that it is possible to model in this way all types of hierarchies between the visible sector gaugino and sfermion masses.

Q-ball dark matter and baryogenesis in high-scale inflation

We investigate the scenario that one flat direction creates baryon asymmetry of the universe, while Q balls from another direction can be the dark matter in the gauge-mediated supersymmetry breaking for high-scale inflation. Isocurvature fluctuations are suppressed by the fact that the Affleck–Dine field stays at around the Planck scale during inflation. We find that the dark matter Q balls can be detected in IceCube-like experiments in the future.

Affleck-Dine baryogenesis and dark matter production after high-scale inflation

The discovery of the primordial B-mode polarization by the BICEP2 experiment indicates inflation with a relatively high energy scale. Taking this indication into account, we propose consistent scenarios to account for the observed baryon and dark matter densities in gravity- and gauge-mediated supersymmetry breaking models. The baryon asymmetry is explained by the Afflck-Dine mechanism, which requires relatively low reheating temperature to avoid a sizable baryonic isocurvature perturbation. The low reheating temperature then requires nonthermal production of dark matter to account for the correct relic density of dark matter. Our scenarios can account for the observations of baryon and dark matter density in gravity and gauge mediation and predict some parameters, including the mass of dark matter.

Weighing the light gravitino mass with weak lensing surveys

We explore the discovery potential of light gravitino mass m_{3/2} by combining future cosmology surveys and collider experiments. The former probe the imprint of light gravitinos in the cosmic matter density field, whereas the latter search signatures of a supersymmetry breaking mechanism. Free-streaming of light gravitinos suppresses the density fluctuations at galactic and sub-galactic length scales, where weak gravitational lensing can be used as a powerful probe. We perform numerical simulations of structure formation to quantify the effect. We then run realistic ray-tracing simulations of gravitational lensing to measure the cosmic shear in models with light gravitino. We forecast the possible reach of future wide-field surveys by Fisher analysis; the light gravitino mass can be determined with an accuracy of m_{3/2}=4\pm 1 eV by a combination of the Hyper Suprime Cam survey and cosmic microwave background anisotropy data obtained by Planck satellite. The corresponding accuracy to be obtained by the future Large Synoptic Survey Telescope is \delta m_{3/2}=0.6 eV. Data from experiments at Large Hadron Collider at 14 TeV will provide constraint at m_{3/2} \simeq 5 eV in the minimal framework of gauge-mediated supersymmetry breaking (GMSB) model. We conclude that a large class of the GMSB model can be tested by combining the cosmological observations and the collider experiments.

Search for direct top squark pair production in events with a [Formula: see text] boson, [Formula: see text]-jets and missing transverse momentum in [Formula: see text] TeV [Formula: see text] collisions with the ATLAS detector.

A search is presented for direct top squark pair production using events with at least two leptons including a same-flavour opposite-sign pair with invariant mass consistent with the Z boson mass, jets tagged as originating from b-quarks and missing transverse momentum. The analysis is performed with proton–proton collision data at sqrt{s}=8{hbox { TeV}} collected with the ATLAS detector at the LHC in 2012 corresponding to an integrated luminosity of 20.3 fb^{-1}. No excess beyond the Standard Model expectation is observed. Interpretations of the results are provided in models based on the direct pair production of the heavier top squark state (tilde{t}_2) followed by the decay to the lighter top squark state (tilde{t}_1) via tilde{t}_2 rightarrow Ztilde{t}_1, and for tilde{t}_1 pair production in natural gauge-mediated supersymmetry breaking scenarios where the neutralino (tilde{chi }^0_1) is the next-to-lightest supersymmetric particle and decays producing a Z boson and a gravitino (tilde{G}) via the tilde{chi }^0_1 rightarrow Ztilde{G} process.