Based on the results from numerous astrophysics experiments, it is currently believed that the majority of matter in the Universe is in some unknown form, known as dark matter. In the past it has been common to model dark matter as a massive particle with weak interactions - either from existing Standard Model forces or from new forces - and often as past of a more complicated theory. In this article, an alternative is presented in which dark matter is in the form of a massive particle with no explicit interactions. It is demonstrated that, in the presence of strongly warped extra dimensions the inherent gravitational interactions of such a particle are sufficient to produce the observed abundance of dark matter without violating existing experimental constraints.
Recently, it has been demonstrated that radion mediated supersymmetry breaking gives the same spectrum as Scherk-Schwarz supersymmetry breaking, and can be interpreted as a dynamical realization of it. We make this connection explicit by exhibiting the direct transformation from one theory to the other. We then use the extreme UV softness of Scherk-Schwarz theories to calculate the one-loop soft masses of matter fields. We do not find any cutoff sensitive ``Kaluza-Klein mediated'' contributions.
In the context of a warped extra-dimension with Standard Model fields in the bulk, we obtain the general flavor structure of the Radion couplings to fermions and show that the result is independent on the particular nature of the Higgs mechanism (bulk or brane localized). These couplings will be generically misaligned with respect to the fermion mass matrix when the fermion bulk mass parameters are not all degenerate. When the Radion is light enough, the generic size of these tree-level flavor changing couplings will be strongly constrained by the experimental bounds on $ΔF=2$ processes. At th…
We point out that in supersymmetric theories with extra dimensions, radius stabilization can give rise to a VEV for the $F$ component of the radius modulus. This gives an important contribution to supersymmetry breaking of fields that propagate in the bulk. A particularly attractive class of models is obtained if the standard-model gauge fields propagate in the bulk, while the quark and lepton fields are localized on a brane. This leads to gaugino mediated supersymmetry breaking without the need for singlets in the hidden sector. We analyze a simple explicit model in which this idea is realize…
We review the equivalence of two approaches to study theories with gauge fields in extra spatial dimensions, namely the ``4D'' approach (with KK states) and the ``5D'' approach (with matching to the 4D theory at the compactification scale). In particular, we reiterate that there are two different power-law scalings of ``effective'' gauge couplings. In a supersymmetric framework with SUSY breaking in the radius modulus, i.e., the field which fixes the size of the extra dimensions, these two approaches seem to give gaugino masses at loop-level (with a possible enhancement due to large number of …
We revisit the case of scalar dark matter interacting just gravitationally with the Standard Model (SM) particles in an extra-dimensional Randall-Sundrum scenario. We assume that both, the dark matter and the Standard Model, are localized in the TeV brane and only interact via gravitational mediators, namely the graviton Kaluza-Klein modes and the radion. We analyze in detail the dark matter annihilation channel into two on-shell KK-gravitons, and contrary to previous studies which overlooked this process, we find that it is possible to obtain the correct relic abundance for dark matter masses…
We study for the first time the possibility that Dark Matter (represented by particles with spin $0,1/2$ or $1$) interacts gravitationally with Standard Model particles in an extra-dimensional Clockwork/Linear Dilaton model. We assume that both, the Dark Matter and the Standard Model, are localized in the IR-brane and only interact via gravitational mediators, namely the Kaluza-Klein (KK) graviton and the radion/KK-dilaton modes. We analyse in detail the Dark Matter annihilation channel into Standard Model particles and into two on-shell Kaluza-Klein towers (either two KK-gravitons, or two rad…
We study the spin-dependence of Dark Matter (DM) particles which interact gravitationally with the Standard Model (SM) in an extra-dimensional Randall-Sundrum scenario. We assume that both the Dark Matter and the Standard Model are confined to the TeV (Infra-red) brane and only interact via gravitational mediators, namely Kaluza-Klein gravitons and the radion. We analyze the different DM annihilation channels and find that it is possible to achieve the presently observed relic abundance of Dark Matter, $Ω_{\rm DM}$, within the freeze-out mechanism for DM particles of spin 0, 1/2 and 1. We stud…
In the usual 5-dimensional Randall-Sundrum scenario with warped geometry of the extra compact dimension, the Goldberger-Wise mechanism for stabilisation of the radius of compactification can lead to a scalar field called the radion. The radion can have implications in TeV-scale physics, which can be especially noticeable if its vacuum expectation value (vev) is not far above a TeV. However a large mass of the first graviton excitation, which seems to be suggested by recent search limit, tends to make the radion vev, far too large in the minimal model. We show that this is not the case if a Gau…
We consider the Minimal Gauge Mediated Model (MGMM) with either fundamental or antisymmetric messenger multiplets and study consequences of messenger-matter mixing. It is shown that constraints on relevant coupling constants and mixing parameters coming from the existing experimental limits on lepton flavor violation and FCNC processes allow a wide range of $\tanβ$ in MGMM with mixing.
We consider the astrophysical bounds on a new form of dark matter, the so called Gravity-mediated Dark Matter. In this scenario, dark matter communicates with us through a mediator sector composed of gravitational resonances, namely a new scalar (radion) and a massive spin-two resonance (massive graviton). We consider specific models motivated by natural electroweak symmetry breaking or weak-scale dark matter in the context of models in warped extra-dimensions and their composite duals. The main Dark Matter annihilation mechanism is due to the interactions of KK gravitons to gauge bosons that …
The inclusive branching ratio $B \to X_sγ$ and the anomalous magnetic moment $g_μ-2$ of the muon are accurately calculated within a minimal gauge-mediated SUSY-breaking model which naturally generates a large $\tanβ$. The predictions are in somewhat better agreement with current experiments, and new data will soon critically test these predictions. Predictions for $B \to X_s\ell^+\ell^-$ branching ratios and asymmetries, to be tested at future colliders, are also presented.
This Letter addresses a provocative question: ``Can the standard electroweak Higgs doublets and their color-triplet partners be the messengers of a low energy gauge-mediated SUSY breaking?" Such a possibility does not seem to be immediately ruled out. If so, it can lead to a very economical scheme with clear-cut predictions quite distinct from those of the conventional gauge-mediated scenario. Namely, we get (i) a single light Higgs below the original SUSY- breaking scale; (ii) tan(beta) = 1; (iii) flavor non-universal, but automatically flavor-conserving soft scalar masses; (iv) a light color…
We study various modifications to the minimal models of gauge mediated supersymmetry breaking. We argue that, under reasonable assumptions, the structure of the messenger sector is rather restricted. We investigate the effects of possible mixing between messenger and ordinary squark and slepton fields and, in particular, violation of universality. We show that acceptable values for the $μ$ and $B$ parameters can naturally arise from discrete, possibly horizontal, symmetries. We claim that in models where the supersymmetry breaking parameters $A$ and $B$ vanish at tree level, $\tanβ$ could be l…
The Minimal Supersymmetric Standard Model with gauge mediated supersymmetry breaking and trilinear R-parity violation is applied to the description of neutrinoless double beta decay. A detailed study of limits on the parameter space coming from the B to (X,gamma) processes by using the recent CLEO results is performed. The importance of two-nucleon and pion-exchange realizations of neutrinoless double beta decay together with gluino and neutralino contributions to this process are addressed. We have deduced new limits on the trilinear R-parity breaking parameter lambda_{111}' from the non-obse…
We investigate the experimental implications of the minimal gauge-mediated low energy supersymmetry breaking (GMLESB) model for Fermilab Tevatron collider experiments. We map out the regions of parameter space of this model that have already been excluded by collider searches and by limits on $b\to sγ$. We use ISAJET to compute the cross sections for a variety of topological signatures which include photons in assocation with multiple leptons, jets and missing transverse energy. The reach in the parameter $Λ$, which fixes the scale of sparticle masses, is estimated to be $\sim 60$, 100 and 135…
We present an extensive analysis of gauge-mediated supersymmetry breaking models with minimal and non-minimal flavour violation. We first demonstrate that low-energy, precision electroweak, and cosmological constraints exclude large "collider-friendly" regions of the minimal parameter space. We then discuss various possibilities how flavour violation, although naturally suppressed, may still occur in gauge-mediation models. The introduction of non-minimal flavour violation at the electroweak scale is shown to relax the stringent experimental constraints, so that benchmark points, that are also…
We calculate the inclusive branching ratio for B--> X_s gamma, the inclusive branching ratios and asymmetries for B--> X_s l+ l- and the anomalous magnetic moment g-2 of the muon, within a minimal gauge-mediated SUSY-breaking model which naturally generates a large ratio tan(beta) of Higgs field vacuum expectation values. These predictions are highly correlated with each other, depending on only two fundamental parameters: the superpartner mass scale and the logarithm of a common messenger mass. The predictions for B--> X_s gamma decay and g-2 are in somewhat better agreement with current expe…
We analise phenomenological implications of two Higgs doublet models with Higgs flavour changing neutral currents suppressed in the quark sector by small entries of the Cabibbo-Kokayashi-Maskawa matrix. This suppression occurs in a natural way since it is the result of a symmetry applied to the Lagrangian. These type of models were proposed some time ago by Branco Grimus and Lavoura. Our results clearly show that these class of models allow for new physical scalars, with masses which are reachable at the LHC. The imposed symmetry severely reduces the number of free parameters and allows for pr…
We examine the reach of the CERN LHC pp collider for supersymmetric models where the dominant contribution to soft SUSY breaking parameters arises from the superconformal anomaly. In the simplest viable anomaly mediated SUSY breaking (AMSB) model, tachyonic slepton squared masses are made positive by adding a universal contribution m_0^2 to all scalars. We use the event generator ISAJET to generate AMSB signal events as a function of model parameter space. Assuming an integrated luminosity of 10 fb-1, the LHC can reach to values of $m_{\tg}\sim 2.3$ TeV for low values of $m_0$, where the dilep…
Diagnostic signals of the minimal model of anomaly mediated supersymmetry breaking are discussed in the context of a $\sqrt{s}$ = 1 TeV $e^+e^-$ linear collider.
We compare the effectiveness of two hypotheses, Natural Flavour Conservation (NFC) and Minimal Flavour Violation (MFV), in suppressing the strength of flavour-changing neutral-currents (FCNCs) in models with more than one Higgs doublet. We show that the MFV hypothesis, in its general formulation, is more stable in suppressing FCNCs than the hypothesis of NFC alone when quantum corrections are taken into account. The phenomenological implications of the two scenarios are discussed analysing meson-antimeson mixing observables and the rare decays B -> mu+ mu-. We demonstrate that, introducing fla…
In gauge-mediated SUSY breaking models, messengers transmit SUSY breaking from a partially hidden sector to the standard model sector via common standard model gauge interactions. The minimal set of messengers has quantum numbers of a $5 + \bar 5$ of SU(5); identical to the quantum numbers of the minimal Higgs sector of an SU(5) GUT. We show in a simple model with messenger masses of order the GUT scale that Higgs - messenger mixing quite naturally leads to a low energy MSSM with gluinos as the lightest supersymmetric particles [LSP]. We study the phenomenological consequences of such a model.
We embed the S-MSSM -- a singlet extension of the minimal supersymmetric standard model with an explicit mu-term and supersymmetric mass term -- in a gauge-mediated supersymmetry breaking scheme. We find that by absolving the singlet of its responsibility for solving the mu-problem, we are instead able to solve the little hierarchy problem naturally. Specifically, we find that even with a minimal embedding of the S-MSSM into a gauge-mediated scheme, we can easily raise the lightest Higgs mass above 114 GeV, while keeping top squarks below the TeV scale, maintaining perturbative unification of …
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 non-minimal flavour-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 flavour-violating supersymmetric particle production at hadron colliders with those related to gluino production, and s…
If SUSY is discovered at the LHC, the task will immediately turn to determining the model of SUSY breaking. Here, we employ a Mixed Modulus-Anomaly Mediated SUSY Breaking (MMAMSB) model with very similar LHC phenomenology to the more conventionally studied Constrained Minimal SUSY Model (CMSSM) and minimal Anomaly Mediated SUSY Breaking (mAMSB) models. We then study whether the models can be distinguished and measured. If we only fit to the various mass edges and mass end-points from cascade decay chains that are normally studied, a unique determination and measurement of the model is problema…
In this letter we demonstrate a new source for large flavor-changing neutral currents within the minimal supersymmetric standard model. At moderate to large tan(beta), it is no longer possible to diagonalize the masses of the quarks in the same basis as their Yukawa couplings. This generates large flavor-violating couplings of the form $\bar b_R d_L H$ and $\bar b_R s_L H$ where H is any of the three neutral, physical Higgs bosons. These new couplings lead to rare processes in the B system such as $B^0 -> μ^+ μ^-$ decay and B-Bbar mixing. We show that the latter is anomalously suppressed, whil…
We present results of our study of tan(beta)-enhanced loop corrections in the Minimal Supersymmetric Standard Model (MSSM) with Minimal Flavour Violation (MFV). We demonstrate that these corrections induce flavour changing neutral current (FCNC) gluino couplings which have a large impact on the Wilson coefficient C_8 of the chromomagnetic operator. To illustrate the phenomenological consequences of this gluino-squark contribution to C_8, we briefly discuss its effect on the mixing-induced CP asymmetry in the decay B_d -> phi K_S.
We consider the minimal supersymmetric standard model within a scenario of large $\tanβ$ and heavy squarks and gluinos, with masses of the heavy neutral Higgs bosons below the TeV scale. We allow for the presence of a large, model independent, source of lepton flavor violation (LFV) in the slepton mass matrix in the $τ-μ$ sector by the mass insertion approximation. We constrain the parameter space using the $τ$ LFV decays together with the $B$-mesons physics observables, the anomalous magnetic moment of the muon and the dark matter relic density. We further impose the exclusion limit on spin-i…
We study the signatures of minimal anomaly mediated supersymmetry breaking in an e^- gamma collider. We demonstrate that the associated production of a sneutrino with the lightest chargino leads to a substantially large signal size. The background is negligibly small, though. Even more interestingly, a measurement of the fundamental supersymmetry breaking parameters could be possible.
We study squark flavour violation in the anomaly mediated supersymmetry broken (AMSB) minimal supersymmetric standard model. Analytical expressions for the three-generational squark mass matrices are derived. We show that the anomaly-induced soft breaking terms have a decreasing amount of squark flavour violation when running from the GUT to the weak scale. Taking into account inter-generational squark mixing, we work out non-trivial constraints from B -> Xs gamma and Bs -> mu mu, which complement each other, as well as B -> tau nu decays. We further identify a region of parameter space where …
Recent LHC data significantly extend the exclusion limits for supersymmetric particles, particularly in the jets plus missing transverse momentum channels. The most recent such data have so far been interpreted by the experiment in only two different supersymmetry breaking models: the constrained minimal supersymmetric standard model (CMSSM) and a simplified model with only squarks and gluinos and massless neutralinos. We compare kinematical distributions of supersymmetric signal events predicted by the CMSSM and anomaly mediated supersymmetry breaking (mAMSB) before calculating exclusion limi…
We show that in a minimal extension of the MSSM by means of an extra U(1) gauge group, the negative mass-squared problem characteristic of the Anomaly Mediated Supersymmetry Breaking scenario is naturally solved by means of Fayet-Iliopoulos D-terms. We derive a set of sum rules for the sparticle masses which are consequences of the resulting framework.
It is known that in the absence of a gauge singlet field, a specific class of supersymmetry (SUSY) breaking non-holomorphic (NH) terms can be soft breaking in nature so that they may be considered along with the Minimal Supersymmetric Standard Model (MSSM) and beyond. There have been studies related to these terms in minimal supergravity based models. Consideration of an F-type SUSY breaking scenario in the hidden sector with two chiral superfields however showed Planck scale suppression of such terms. In an unbiased point of view for the sources of SUSY breaking, the NH terms in a phenomenolo…
Despite their appealing features, models with gauge-mediated supersymmetry breaking (GMSB) typically present a high degree of fine-tuning, due to the initial absence of the top trilinear scalar couplings, $A_t=0$. In this paper, we carefully evaluate such a tuning, showing that is worse than per mil in the minimal model. Then, we examine some existing proposals to generate $A_t\neq 0$ term in this context. We find that, although the stops can be made lighter, usually the tuning does not improve (it may be even worse), with some exceptions, which involve the generation of $A_t$ at one loop or t…
In the so-called Planckian Interacting Dark Matter (PIDM) scenario, superheavy dark matter particles are produced after inflation by gravity-mediated interactions through the freeze-in mechanism. In the minimal PIDM model, the absence of any additional direct coupling with Standard Model particles is assumed. However, for scalar dark matter particles there is no symmetry that suppresses the Higgs portal coupling. In this paper, we therefore study the impact of a non-zero interaction with the Higgs field on the PIDM paradigm for scalar dark matter. In particular, we fully explore the model para…
We classify the variety of low-energy supersymmetric signatures that can be probed at future colliders. We focus on phenomena associated with the minimal supersymmetric extension of the Standard Model. The structure of the supersymmetry-breaking introduces additional model assumptions. The approaches considered here are supergravity-mediated and gauge-mediated supersymmetry-breaking. Alternative phenomenologies arising in non-minimal and/or R-parity-violating approaches are also briefly examined.
We consider the Affleck-Dine baryogenesis comprehensively in the minimal supersymmetric standard model with gauge-mediated supersymmetry breaking. Considering the high temperature effects, we see that the Affleck-Dine field is naturally deformed into the form of the Q ball. In the natural scenario where the initial amplitude of the field and the A-terms are both determined by the nonrenormalizable superpotential, we obtain a narrow allowed region in the parameter space in order to explain the baryon number and the dark matter of the universe simultaneously. Therefore, the Affleck-Dine baryogen…
We study in some detail the next-to-minimal supersymmetric standard model with gauge mediation of supersymmetry breaking. We find that it is feasible to spontaneously generate values of the Higgs mass parameters $μ$ and $B_μ$ consistent with radiative electroweak symmetry breaking. The model has a phenomenologically viable particle spectrum. Messenger sneutrinos with mass in the range 6 to 25 TeV can serve as cold dark matter. It is also possible to evade the cosmological domain wall problem in this scenario.
We have considered neutralino to be the lightest supersymmetric particle (LSP) in the framework of minimal Anomaly Mediated Supersymmetric (mAMSB) model. We have studied variation of neutralino mass with the supersymmetric parameters. Considering these neutralinos to be the candidates for weakly interacting massive particle (WIMP) or cold dark matter (CDM), we have calculated the neutralino nucleon scalar cross-sections and compared them with DAMA-NaI neutralino direct detection search results. From this study we observe that the mAMSB model results cannot explain the allowed region in WIMP ma…
We constrain the parameter space of the minimal and gaugino-assisted anomaly mediation, and gaugino mediation models by requiring that the electroweak vacuum corresponds to the deepest minimum of the scalar potential. In the framework of anomaly mediation models we find strong lower bounds on slepton and squark masses. In the gaugino mediation models the mass spectrum is forced to be at the TeV scale. We find extensive regions of the parameter space which are ruled out, even at low tan(beta). The implications of these results on the g-2 of the muon are also analyzed.
We consider the prospects for the direct detection of dark matter in pure gravity meditation (PGM) models of supersymmetry breaking. Minimal PGM models require only two parameters, the gravitino mass, $m_{3/2}$, which sets the UV mass for all scalar masses, and $\tanβ$. Gaugino masses are generated through anomaly mediation. Typically the lightest supersymmetric state (the dark matter candidate) is a wino. Here, we consider a one-parameter extension of the minimal model by allowing the Higgs soft masses to deviate from universality. For simplicity, we take these to be equal and use the $μ$-ter…
In this thesis we examine three different models in the MSSM context, all of which have significant supergravity anomaly contributions to their soft masses. These models are the so-called Minimal, Hypercharged, and Gaugino Anomaly Mediated Supersymmetry Breaking models. We explore some of the string theoretical motivations for these models and proceed by understanding how they would appear at the Large Hadron Collider (LHC). Our major results include calculating the LHC reach for each model's parameter space and prescribing a method for distinguishing the models after the collection of 100 fb^…
We consider the Minimal Gauge Mediated Model (MGMM) with either fundamental or antisymmetric messenger multiplets and study consequences of messenger-matter mixing. We find that in these models, unlike MGMM without mixing, wide range of $\tanβ$ is allowed. It is shown that existing experimental limits on processes with lepton flavor violation, and on $K^0-\bar{K}^0$, $D^0-\bar{D}^0$ and $B^0-\bar{B}^0$ - mixing place significant constraints on relevant coupling constants and mixing parameters. On the other hand, the contributions of the messenger-matter mixing to the rates of $τ\to eγ$, $τ\to …
Anomaly mediation models are well motivated supersymmetry breaking scenarios which appear as alternatives to the mSUGRA paradigm. These models are quite compelling from the theoretical point of view and it is therefore important to test if they are also viable models for phenomenology. We perform a study of these models in the light of all standard flavour, collider and dark matter constraints, including also the recent Higgs boson measurements for the mass and signal strengths in the different decay channels. The minimal AMSB scenario can satisfy in part of its parameter space the dark matter…
We present a minimal model of fermionic dark matter (DM), where a singlet Dirac fermion can interact with the Standard Model (SM) particles via the torsion field of gravitational origin. In general, torsion can be realized as an antisymmetric part of the affine connection associated with the spacetime diffeomorphism symmetry and thus can be thought of as a massive axial vector field. Because of its gravitational origin, the torsion field couples to all the fermion fields including the DM with equal strength, which makes the model quite predictive. The DM is naturally stable without any imposit…
The phenomenology associated with gauge-mediated supersymmetry breaking is presented. A renormalization group analysis of the minimal model is performed in which the constraints of radiative electroweak symmetry breaking are imposed. The resulting superpartner and Higgs boson spectra are highly correlated and depend on only a few parameters. Superpartner mass ratios and sum rules are identified which can be tested at future colliders. Some of these relations are logarithmically sensitive to the messenger scale, while others allow gauge-mediation to be distinguished from other schemes for tansm…
We derive the general resummed effective Lagrangian for Higgs-mediated flavour-changing neutral-current (FCNC) interactions in the Minimal Supersymmetric Standard Model (MSSM), without resorting to particular assumptions that rely on the squark-mass or the quark-Yukawa structure of the theory. In our derivation we also include the possibility of explicit CP violation through the Cabibbo--Kobayashi--Maskawa mixing matrix and soft supersymmetry-breaking mass terms. The advantages of our resummed FCNC effective Lagrangian are explicitly demonstrated within the context of phenomenologically motiva…
Institute of Particle and Nuclear Studies, High Energy Accelerator Research Organization (KEK)（高能加速器研究机构粒子核研究所在）；The Graduate University for Advanced Studies (SOKENDAI)（综合研究大学院大学）；Department of Physics, College of Humanities and Sciences, Nihon University（日本大学文理学部物理学科）；Center for Gravitational Physics and Quantum Information, Yukawa Institute for Theoretical Physics, Kyoto University（京都大学汤川理论物理研究所引力物理与量子信息研究中心）；Kobayashi-Maskawa Institute for the Origin of Particles and the Universe, Nagoya University（名古屋大学小林-益川粒子宇宙起源研究所）
We propose a new approach to generate messenger-matter interactions in deflected anomaly mediated SUSY breaking mechanism from typical holomorphic messenger-matter mixing terms in the Kahler potential. This approach is a unique feature of AMSB and has no analog in GMSB-type scenarios. New coupling strengths from the scaling of the (already known) Yukawa couplings always appear in this approach. With messenger-matter interactions in deflected AMSB, we can generate a realistic soft SUSY breaking spectrum for next-to-minimal supersymmetric standard model(NMSSM). Successful electroweak symmetry br…
Non-minimal simplified extensions of the Standard Model have gained considerable currency in the context of dark matter searches at the LHC, since they predict enhanced mono-Higgs and mono-$W/Z$ signatures over large parts of the parameter space. However, these non-minimal models obviously lack the simplicity and directness of the original simplified models, and are more heavily dependent on the model assumptions. We propose to classify these models generically on the basis of additional mediator(s) and dark matter particles. As an example, we take up a scenario involving multiple pseudoscalar…
We study the LHC phenomenology of the next-to-minimal model of gauge-mediated supersymmetry breaking (NMGMSB), both for Run I and Run II. The Higgs phenomenology of the model is consistent with observations: a 125 GeV Standard Model-like Higgs which mixes with singlet-like state of mass around 90 GeV that provides a 2$σ$ excess at LEP II. The model possesses regions of parameter space where a longer-lived lightest neutralino decays in the detector into a gravitino and a $b-$jet pair or a tau pair. We investigate current lower bounds on sparticle masses and the discovery potential of the model,…
We propose the hybrid gravity-gauge mediated supersymmetry breaking where the gravitino mass is about several GeV. The strong constraints on supersymmetry viable parameter space from the CMS and ATLAS experiments at the LHC can be relaxed due to the heavy colored supersymmetric particles, and it is consistent with null results in the dark matter (DM) direct search experiments such as XENON100. In particular, the possible maximal flavor and CP violations from the relatively small gravity mediation may naturally account for the recent LHCb anomaly. In addition, because the gravitino mass is arou…
We study in some detail the spectral phenomenology of models in which supersymmetry is dynamically broken and transmitted to the supersymmetric partners of the quarks, leptons and gauge bosons, and the Higgs bosons themselves, via the usual gauge interactions. We elucidate the parameter space of what we consider to be the minimal model, and explore the regions which give rise to consistent radiative electroweak symmetry breaking. We include the weak-scale threshold corrections, and show how they considerably reduce the scale dependence of the results. We examine the sensitivity of our results …
We consider a supersymmetric model motivated by a SO(10) grand unified theory: the gauge sector near the supersymmetry scale consists of SU(3)_c x SU(2)_L x U(1)_R x U(1)_{B-L}. We embed this model in minimal gauge mediation and incorporate neutrino data via an inverse seesaw mechanism. Also in this restricted model, the additional D terms can rise the light Higgs mass in a sizable way. Therefore, it is much easier to obtain m_h \simeq 125 GeV without the need to push the supersymmetry spectrum to extremely large values as it happens in models with minimal supersymmetric standard model particl…
The parameters of the Minimal Supersymmetric Standard Model appear to require uncomfortably precise adjustment in order to reconcile the electroweak symmetry breaking scale with the lower mass limits on a neutral Higgs scalar boson. This problem can be significantly ameliorated in models with a running gluino mass parameter that is smaller than the wino mass near the scale of unification of gauge couplings. A "compressed" superpartner mass spectrum results; compared to models with unified gaugino masses, the ratios of the squark and gluino masses to the lightest superpartner mass are reduced. …
We study the generation of primordial magnetic fields, coherent over cosmologically interesting scales, by gravitational creation of charged scalar particles during the reheating period. We show that magnetic fields consistent with those detected by observation may obtained if the particle mean life τ_s is in the range 10^{-14} sec \leq τ_s \leq 10{-7} sec. We apply this mechanism to minimal gauge mediated supersymmetry-breaking models, in the case in which the lightest stau \tildeτ_1 is the next-to-lightest supersymmetric particle. We show that, for a large range of phenomenologically accepta…
Minimal Supersymmetric Standard Model with gauge mediated supersymmetry breaking has all the necessary ingredients for a successful sub-eV Hubble scale inflation $H_{\rm inf} \sim 10^{-3}-10^{-1}$ eV. The model generates the right amplitude for scalar density perturbations and a spectral tilt within the range, $0.90 \leq n_s \leq 1$. The reheat temperature is $T_{\rm R} \ls 10$ TeV, which strongly prefers electroweak baryogenesis and creates the right abundance of gravitinos with a mass $m_{3/2} \gs 100$ keV to be the dark matter.
A review of supersymmetry theory and phenomenology is presented. Topics discussed include: gravity-mediated (SUGRA) and gauge-mediated (GMSB) supersymmetry breaking models; an overview of non-universal soft-supersymmetry-breaking masses and the resulting experimental implications; the phenomenology of and constraints on the possibility that a massive gluino is the lightest supersymmetric particle; current status of the phenomenology of the Higgs bosons of the minimal and next-to-minimal supersymmetric models; and, the signals for GMSB and/or R-parity-violating models coming from delayed decays…
We present a particle physics model based on a ten-dimensional (10D) super Yang-Mills (SYM) theory compactified on magnetized tori preserving four-dimensional ${\cal N}=1$ supersymmetry. The low-energy spectrum contains the minimal supersymmetric standard model with hierarchical Yukawa couplings caused by a wavefunction localization of the chiral matter fields due to the existence of magnetic fluxes, allowing a semi-realistic pattern of the quark and the lepton masses and mixings. We show supersymmetric flavor structures at low energies induced by a moduli-mediated and an anomaly-mediated supe…
Affleck-Dine (AD) baryogenesis along a d=6 flat direction in gauge-mediated supersymmetry-breaking (GMSB) models can produce unstable Q-balls which naturally have field strength similar to the messenger scale. In this case a new kind of Q-ball is formed, intermediate between gravity-mediated and gauge-mediated type. We study in detail these new Q-ball solutions, showing how their properties interpolate between standard gravity-mediated and gauge-mediated Q-balls as the AD field becomes larger than the messenger scale. It is shown that E/Q for the Q-balls can be greater than the nucleon mass bu…
