We study the phenomenology of generic supergravity models in which gravity mediation naturally competes with gauge mediation as the origin of supergravity-breaking. This class of hybrid models has been recently motivated in string inspired constructions and differs from usual gauge mediated supersymmetry breaking models in having messenger masses of order of the GUT scale. In these scenarios the gravitino can be the lightest supersymmetric particle in wide regions of the parameter space and therefore a potential candidate for dark matter. We investigate this possibility, imposing the WMAP bound on its relic abundance and taking into account constraints from Big Bang nucleosynthesis. We show that in these constructions viable gravitino dark matter can be obtained in specific regions of the parameter space, featuring large values of tan(beta) and where the supersymmetry breaking mechanism is dominated by gauge mediation.
We study general conditions for the gravitino to be the lightest supersymmetric particle (LSP) in models with gravity mediated supersymmetry breaking. We find that the decisive quantities are the Kaehler potential K and the gauge kinetic function f. In constrained MSSM (CMSSM) type models, the gravitino LSP occurs if the gaugino mass at the GUT scale is greater than approximately 2.5 gravitino masses. This translates into \sqrt{K"}/f' < 0.2, where the derivatives are taken with respect to the dominant SUSY breaking field. This requirement can easily be satisfied in string-motivated setups.
We revisit the F-term hybrid inflation model in supergravity. In particular, we point out that a constant term in the superpotential has significant effects on the inflaton dynamics. It is shown that the hybrid inflation model suffers from several potential problems: tuning of the initial condition, gravitino overproduction and formation of cosmic strings, for both minimal and non-minimal Kahler potentials. These problems can only be avoided in gauge-mediated SUSY breaking models where the gravitino is relatively light and the constant term in the superpotential is not important. Implications …
It was recently found that the decay of inflaton and the SUSY breaking field produces many gravitinos in the gravity mediation scenario. These discoveries led to an exclusion of many inflation models such as chaotic, (smooth) hybrid, topological and new inflation models. Under these circumstances we searched for a successful inflation model and found that the ``inverted'' hybrid inflation models can solve the gravitino overproduction problem by their distinctive shape of the potential. Furthermore, we found that this inflation model simultaneously can explain the observed baryon asymmetry thro…
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…
It is known that supersymmetric hybrid inflation model may require severe tunings on the initial condition for large gravitino mass of order 100 - 1000 TeV due to the constant term in the superpotential. We propose a modified hybrid inflation model, where the constant term is suppressed during inflation and generated after inflation by replacing a constant term with dynamical field. In this modified model, successful inflation consistent with large gravitino mass takes place without severe tunings on the initial condition. Constraint from cosmic strings is also relaxed.
The gravitino dark matter hypothesis in the brane cosmology is studied. The theoretical framework is the CMSSM for particle physics and RS II brane model for gravity. It is found that the gravitino can play the role of dark matter in the universe and we determine what the gravitino mass should be for different values of the five-dimensional Planck mass. An upper bound is obtained for the latter.
We propose a novel reformulation of supersymmetric (more precisely $μ$-) hybrid inflation based on a local U(1) or any suitable extension of the minimal supersymmetric standard model (MSSM) which also resolves the $μ$ problem. We employ a suitable Kahler potential which effectively yields quartic inflation with non-minimal coupling to gravity. Imposing the gravitino Big Bang Nucleosynthesis (BBN) constraint on the reheat temperature ($T_r \lesssim 10^6$ GeV) and requiring a neutralino LSP, the tensor to scalar ratio ($r$) has a lower bound $r \gtrsim 0.004$. The U(1) symmetry breaking scale li…
We propose a retrofitted gravity mediation model which alleviates the gravitino overproduction from decays of an inflaton and a supersymmetry breaking field. In the model, we introduce an approximate U(1) symmetry under which the supersymmetry breaking field is charged, although it is broken by a mass term of messenger fields to generate gaugino masses of order the weak scale. In a low-scale inflation model, we find regions in which the gravitino overproduction problem is avoided.
We investigate supersymmetric hybrid inflation in a realistic model based on the gauge symmetry $SU(4)_c \times SU(2)_L \times SU(2)_R$. The minimal supersymmetric standard model (MSSM) $μ$ term arises, following Dvali, Lazarides, and Shafi, from the coupling of the MSSM electroweak doublets to a gauge singlet superfield which plays an essential role in inflation. The primordial monopoles are inflated away by arranging that the $SU(4)_c \times SU(2)_L \times SU(2)_R$ symmetry is broken along the inflationary trajectory. The interplay between the (above) $μ$ coupling, the gravitino mass, and th…
It has been recently shown that it is possible to excite gravitinos in an expanding background due to a time varying scalar field oscillating at the bottom of the inflationary potential. The two components of the gravitino, namely helicity 1/2 and helicity 3/2, are excited differently due to the presence of different time varying mass scales in the problem. In this paper we analyse the production of both the helicities in a multi-chiral scenario, in particular focusing on a general model of hybrid inflation. Fermion production in hybrid models is very much different from that of the chaotic mo…
We investigate compatibility of the pure gravity mediation (or the minimal split supersymmetry) with chaotic inflation models in supergravity. We find that an approximate Z2 parity of the inflaton is useful to suppress gravitino production from thermal bath and to obtain consistent inflation dynamics. We discuss production of the lightest supersymmetric particle through the decay of the inflaton with the approximate Z2 symmetry and find that a large gravitino mass is favored to avoid the overproduction of the lightest supersymmetric particle, while a lower gravitino mass requires tuning of par…
We study models with contributions of similar size to the soft masses from anomaly- and gravity mediation, thereby curing the tachyonic slepton problem of anomaly mediation. A possible origin of this hybrid setup in a 5-dimensional brane world is briefly discussed. The absence of excessive flavor violation is explained by alignment. The gravitino can be heavy enough so that the gravitino problem of supersymmetric theories with leptogenesis is avoided. The model has a characteristic signature: It predicts the distinctive gaugino mass pattern of anomaly mediation and, at the same time, O(1) slep…
The simplest model of pure gravity mediation contains only two free parameters: the gravitino mass and \tanβ. Scalar masses are universal at some high energy renormalization scale and gaugino masses are determined through anomalies and depend on the gravitino mass and the gauge couplings. This theory requires a relatively large gravitino mass (m_{3/2}\gtrsim 300\,TeV) and a limited range in \tan β\simeq 1.7--2.5. Here we generalize the theory to allow for non-universality in the Higgs soft masses. This introduces zero, one or two new free parameters associated with Higgs soft masses. This gene…
We study the consequences of the gravitino decay into dark matter. We suppose that the lightest neutralino is the main component of dark matter. In our framework gravitino is heavy enough to decay before Big Bang Nucleosynthesis starts. We consider a model coming from a five dimensional supergravity compactified on $S^1/Z_2$ with gravity in the bulk and matter localized on tensionless branes at the orbifold fixed points. We require that the dark matter, which is produced thermally and in the decay of Kaluza-Klein modes of gravitino, has an abundance compatible with observation. We deduce from …
We examine dark matter production rates in supersymmetric axion models typified by the mass hierarchy m_gravitino << m_neutralino << m_axino. In such models, one expects the dark matter to be composed of an axion/gravitino admixture. After presenting motivation for how such a mass hierarchy might arise, we examine dark matter production in the SUSY Kim-Shifman-Vainshtein-Zakharov (KSVZ) model, the SUSY Dine-Fischler-Srednicki-Zhitnitsky (DFSZ) model and a hybrid model containing contributions from both KSVZ and DFSZ. Gravitinos can be produced thermally and also non-thermally from axino, saxio…
We consider models of Pure Gravity Mediation in which scalar mass universality is imposed at the grand unified scale and gaugino masses are generated through loops. The minimal model requires a very restricted range for $\tan β\approx 2-3$ and scalar masses (set by the gravitino mass) of order 300 TeV - 1.5 PeV in order to obtain a Higgs mass near 126 GeV. Here we augment the minimal model with one or more sets of vector multiplets (either a ${10}$ and $\bar {10}$ pair or one or more $5$ and $\bar 5$ pairs). If coupled to the MSSM Higgs, these allow for radiative electroweak symmetry breaking …
We present a successful realization of supersymmetric $μ$-hybrid inflation model based on a gauged $U(1)_{B-L}$ extension of the minimal supersymmetric standard model, with the soft supersymmetry breaking terms are playing an important role. Successful non-thermal leptogenesis with gravitino dark matter yields a reheat temperature in the range $2 \times 10^{7} \lesssim T_R \lesssim 5 \times 10^{9}$ GeV. This corresponds to the predictions $2 \times 10^{-18} \lesssim r\lesssim 4 \times 10^{-13}$ for the tensor to scalar ratio, and $-2 \times 10^{-6} \lesssim dn_s/d\ln k \lesssim -5 \times 10^{-…
We consider supersymmetric models where anomaly and gravity mediation give comparable contributions to the soft terms and discuss how this can be realized in a five-dimensional brane world. The gaugino mass pattern of anomaly mediation is preserved in such a hybrid setup. The flavorful gravity-mediated contribution cures the tachyonic slepton problem of anomaly mediation. The supersymmetric flavor puzzle is solved by alignment. We explicitly show how a working flavor-tachyon link can be realized with Abelian flavor symmetries and give the characteristic signatures of the framework, including O…
We consider compactifications induced by the gravitino field of eleven dimensional supergravity. Such compactifications are not trivial in the sense that the gravitino profiles are not related to pure bosonic ones by means of a supersymmetry transformation. The basic property of such backgrounds is that they admit $ψ$-torsion although they have vanishing Riemann tensor. Thus, these backgrounds may be considered also as solutions of the teleparallel formulation of supergravity. We construct two classes of solutions, one with both antisymmetric three-form field, gravity and gravitino and one wit…
We study the production of spin 1/2 gravitinos in a thermal Universe. Taking into account supersymmetry breaking due to the finite thermal energy density of the Universe, there is a large enhancement in the cross section of production of these gravitino states. We consider gravitinos with zero temperature masses of 0.1 eV, 1 keV, 100 GeV and 30 TeV as representative of gauge mediated, gravity mediated and anomaly mediated supersymmetry breaking scenarios. We find that the abundance of gravitinos produced in the early Universe is very high for gravitinos of mass 1 keV and 100 GeV. The gravitino…
To solve the fine-tuning problem in $μ$-Term Hybrid Inflation, we will realize the supersymmetry scenario with the TeV-scale supersymmetric particles and intermediate-scale gravitino from anomaly mediation, which can be consistent with the WMAP and Planck experiments. Moreover, we for the first time propose the $μ$-term hybrid inflation in no-scale supergravity. With four Scenarios for the $SU(3)_C\times SU(2)_L\times SU(2)_R\times U(1)_{B-L}$ model, we show that the correct scalar spectral index $n_s$ can be obtained, while the tensor-to-scalar ratio $r$ is prediced to be tiny, about $10^{-10…
It is known that gravitinos are non-thermally produced in inflaton decay processes, which excludes many inflation models for a wide range of the gravitino mass. We find that the constraints from the gravitino overproduction can be greatly relaxed if the supersymmetry breaking field is much lighter than the inflaton, and if the dynamical scale of the supersymmetry breaking is higher than the inflaton mass. In particular, we show that many inflation models then become consistent with the pure gravity mediation with O(100)TeV gravitino which naturally explains the recently observed Higgs boson ma…
Moduli, modulini and the gravitino have gravitational-strength interactions, and thermal collisions after reheating create all of them with roughly the same abundance. With their mass of order $100\GeV$, corresponding to gravity-mediated supersymmetry breaking, this leads to the well-known bound $γT\sub R\lsim 10^9\GeV$ on the reheat temperature, where $γ\leq 1$ is the entropy dilution factor. The vacuum fluctuation also creates these particles, with abundance determined by the solution of the equation for the mode function. Taking the equation in each case to be the one corresponding to a fre…
We propose the gravitino dark matter in the gravity mediated supersymmetry breaking scenario. The mass hierarchies between the gravitino and other superparticles can be achieved by the nontrivial Kähler metric of the supersymmetry breaking field. As a concrete model, we consider the five-dimensional supergravity model in which moduli are stabilized, and then one of the moduli induces the slow-roll inflation. It is found that the relic abundance of the gravitino and the Higgs boson mass reside in the allowed range without a severe fine-tuning.
We propose a new swampland conjecture stating that the limit of vanishing gravitino mass corresponds to the massless limit of an infinite tower of states and to the consequent breakdown of the effective field theory. We test our proposal in large classes of models coming from compactification of string theory to four dimensions, where we identify the Kaluza-Klein nature of the tower of states becoming light. We point out a general relation between the gravitino mass and abelian gauge coupling in models with extended supersymmetry, which can survive also in examples with minimal supersymmetry. …
We investigate the leptogenesis via decays of heavy Majorana neutrinos which are produced non-thermally in inflaton decays. We make a comprehensive study on the leptogenesis assuming various supersymmetric (SUSY) models for hybrid, new and topological inflations. For an estimation of the lepton asymmetry we adopt the Froggatt-Nielsen mechanism for mass matrices of quarks and leptons. We find that all of these models are successful to produce the lepton asymmetry enough to explain the baryon number in the present universe. Here we impose low reheating temperatures such as $T_R \lesssim 10^8$ Ge…
We present a solution to the gravitino problem, which arises in the NMSSM, allowing for sparticle spectra from ordinary gravity-mediated supersymmetry breaking with weak-scale gravitino dark matter. The coupling, which links the singlet to the MSSM sector, enhances the tree-level Higgs mass, providing an attractive explanation why the observed Higgs boson is so heavy. The same coupling induces very efficient pair-annihilation processes of the neutralino NLSP. Its relic abundance can be sufficiently suppressed to satisfy the strong constraints on late decaying relics from primordial nucleosynth…
We extend the swampland from effective field theories (EFTs) inconsistent with quantum gravity to EFTs inconsistent with quantum supergravity. This enlarges the swampland to include EFTs that become inconsistent when the gravitino is quantized. We propose the Gravitino Swampland Conjecture: the gravitino sound speed must be non-vanishing in all EFTs that are low energy limits of quantum supergravity. This seemingly simple statement has important consequences for both theories and observations. The conjecture is consistent with and supported by the KKLT and LVS scenarios for moduli stabilizatio…
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 can…
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…
We study the consequences of the gravitino decay into dark matter. We suppose that the lightest neutralino is the main component of dark matter. In our framework gravitino is heavy enough to decay before Big Bang Nucleosynthesis starts. We consider a model coming from a five dimensional supergravity compactified on $S^1/Z_2$ with gravity in the bulk and matter localized on tensionless branes at the orbifold fixed points. We require that the dark matter, which is produced thermally and in the decay of Kaluza-Klein modes of gravitino, has an abundance compatible with observation. We deduce from …
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…
We consider $μ$-term hybrid inflation which, in its minimal format with gravity mediated supersymmetry breaking, leads to split supersymmetry. The MSSM $μ$-term in this framework is larger than the gravitino mass $m_G$, and successful inflation requires $m_G$ (and hence also $|μ|$) $\gtrsim 5 \times 10^7$ GeV, such that the gravitino decays before the LSP neutralino freezes out. Assuming universal scalar masses of the same order as $m_G$, this leads to split supersymmetry. The LSP wino with mass $\simeq$ 2 TeV is a plausible dark matter candidate, the gluino may be accessible at the LHC, and t…
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…
We investigate O'Raifeartaigh-type models for F-term supersymmetry breaking in gauge mediation scenarios in the presence of gravity. It is pointed out that the vacuum structure of those models is such that in metastable vacua gravity mediation contribution to scalar masses is always suppressed to the level below 1 percent, almost sufficient for avoiding FCNC problem. Close to that limit, gravitino mass can be in the range 10-100 GeV, opening several interesting possibilities for gauge mediation models, including Giudice-Masiero mechanism for mu and Bmu generation. Gravity sector can include st…
We study gravitational particle production of the massive spin-$3/2$ Rarita-Schwinger field, and its close relative, the gravitino, in FRW cosmological spacetimes. For masses lighter than the value of the Hubble expansion rate after inflation, $m_{3/2} \lesssim H$, we find catastrophic gravitational particle production, wherein the number of gravitationally produced particles is divergent, caused by a transient vanishing of the helicity-1/2 gravitino sound speed. In contrast with the conventional gravitino problem, the spectrum of produced particles is dominated by those with momentum at the U…
We consider super-gravity models in which the lightest supersymmetric particle (LSP) is a stable gravitino. The next-to-lightest supersymmetric particle (NLSP) freezes out with its thermal relic density and then decays after $(10^5-10^{10})$ sec, injecting high-energy photons into the cosmic plasma. These photons heat up the electron plasma which then thermalizes with the cosmic microwave background (CMB) via Compton scattering, bremsstrahlung and double-Compton scattering. Contrary to previous studies which assume instantaneous energy injection, we solve the full kinetic equation for the phot…
In the supersymmetric standard model there exist pure gravity contributions to the soft mass parameters which arise via the superconformal anomaly. We consider the low-energy phenomenology with a mass spectrum dominated by the anomaly-induced contributions. In a well-defined minimal model we calculate electroweak symmetry breaking parameters, scalar masses, and the full one-loop splitting of the degenerate Wino states. The most distinctive features are gaugino masses proportional to the corresponding gauge coupling beta-functions, the possibility of a Wino as the lightest supersymmetric partic…
We review some recent trends in the inflationary model building, the supersymmetry (SUSY) breaking, the gravitino Dark Matter (DM) and the Primordial Black Holes (PBHs) production in supergravity. The Starobinsky inflation can be embedded into supergravity when the inflaton belongs to the massive vector multiplet associated with a (spontaneously broken) $U(1)$ gauge symmetry. The SUSY and R-symmetry can be also spontaneously broken after inflation by the (standard) Polonyi mechanism. Polonyi particles and gravitinos are super heavy and can be copiously produced during inflation via the Schwing…
Successful models of Pure Gravity Mediation (PGM) with radiative electroweak symmetry breaking can be expressed with as few as two free parameters which can be taken as the gravitino mass and $\tan β$. These models easily support a 125-126 GeV Higgs mass at the expense of a scalar spectrum in the multi-TeV range and a much lighter wino as the lightest supersymmetric particle. In these models, it is also quite generic that the Higgs mixing mass parameter, $μ$, which is determined by the minimization of the Higgs potential is also in the multi-TeV range. For $μ> 0$, the thermal relic density of …
In $μ$-hybrid inflation a nonzero inflaton vacuum expectation value induced by supersymmetry breaking is proportional to the gravitino mass $m_{3/2}$, which can be exploited to resolve the minimal supersymmetric standard model $μ$ problem. We show how this scenario can be successfully implemented with $m_{3/2} \sim 1-100$ TeV and reheat temperature as low as $10^6$ GeV by employing a minimal renormalizable superpotential coupled with a well defined non-minimal Kähler potential. The tensor-to-scalar ratio $r$, a canonical measure of primordial gravity waves in most cases is less than or of the …
Supersymmetry, Large Extra Dimensions and the Gravitino Conjecture
Max-Planck-Institut für Physik（马克斯·普朗克物理研究所）；Arnold Sommerfeld Center for Theoretical Physics, Ludwig-Maximilians-Universität München（慕尼黑大学阿诺德·索末菲理论物理中心）；Department of Physics and Astronomy “Ettore Majorana”, University of Catania（卡塔尼亚大学埃托雷·马约拉纳物理与天文学系）；INFN-Sezione di Catania（意大利国家核物理研究所卡塔尼亚分部）
We study a version of Starobinsky-like inflation in no-scale supergravity (SUGRA) where a Polonyi term in the hidden sector breaks supersymmetry (SUSY) after inflation, providing a link between the gravitino mass and inflation. We extend the theory to the visible sector and calculate the soft-SUSY breaking parameters depending on the modular weights in the superpotential and choice of Kähler potential. We are led to either no-scale SUGRA or pure gravity mediated SUSY breaking patterns, but with inflationary constraints on the Polonyi term setting a strict upper bound on the gravitino mass $m_…
We explore scenarios in which the graviton is not a fundamental degree of freedom at short distances but merely emerges as an effective degree of freedom at long distances. In general, the scale of such graviton `compositeness', Lambda_g, can only be probed by measuring gravitational forces at short distances, which becomes increasingly difficult and eventually impossible as the distance is reduced. Here, however, we point out that if supersymmetry is an underlying symmetry, the gravitino can be used as an alternative probe to place a limit on Lambda_g in a collider environment, by demonstrati…
As is well known, the gravitational degrees of freedom contained in $R+ζR^{2}$ (super)gravity lead to Starobinsky's potential, in a one-field setting for inflationary Cosmology that appears favored by Planck data. In this letter we discuss another interesting aspect of this model, related to gravitino production, with emphasis on the corresponding mass spectrum. Assuming that supersymmetry is broken at a very high scale, Super Heavy Gravitino Dark Matter (SHGDM) and Starobinsky's inflation can be coherently unified in a $R+ζR^{2}$ supergravity. Gravitinos are assumed to be the Lightest Supersy…
Standard Big Bang nucleosynthesis at baryonic density as inferred by WMAP implies a primordial Li7 abundance factor of two to three larger than that inferred by observations of low--metallicity halo stars. Recent observations of Li6 in halo stars suggest a pre--galactic origin of this isotope, which is exceedingly difficult to explain by putative high redshift cosmic ray populations. We investigate if one or both of these lithium problems may be solved by late decaying relic particles in the Constrained Minimal Supersymmetric Standard Model (CMSSM) coupled to gravity. Assuming that the graviti…
We investigate the possibility that the hot thermal phase of the early universe is ignited in consequence of the B-L phase transition, which represents the cosmological realization of the spontaneous breaking of the Abelian gauge symmetry associated with B-L, the difference between baryon number B and lepton number L. Prior to the B-L phase transition, the universe experiences a stage of hybrid inflation. Towards the end of inflation, the false vacuum of unbroken B-L decays, which entails tachyonic preheating as well as the production of cosmic strings. The dynamics of the B-L breaking Higgs f…
We present a novel mechanism of supersymmetry breaking embeddable in string theory and simultaneously sharing the main advantages of (sequestered) gravity and gauge mediation. It is driven by a Scherk-Schwarz deformation along a compact extra dimension, transverse to a D-brane stack supporting the supersymmetric extension of the Standard Model. This fixes the magnitude of the gravitino mass, together with that of the gauginos of a bulk gauge group, at a scale as high as $10^{10}$ GeV. Supersymmetry breaking is mediated to the observable sector dominantly by gauge interactions using massive mes…
We revisit the hybrid inflation model gauged by $U(1)_{B-L}$ extension of the Minimal Supersymmetric Standard Model (MSSM) in a no-scale background. Considering a single predictive framework, we study inflation, leptogenesis, gavitino cosmology, and the stochastic background of gravitational waves produced by metastable cosmic strings. The spontaneous breaking of $U(1)_{B-L}$ at the end of inflation produces a network of metastable cosmic strings while, the interaction between $U(1)_{B-L}$ Higgs field and the neutrinos generate heavy Majorana masses for the right-handed neutrinos. The heavy Ma…
The gauge-mediated model of supersymmetry breaking implies that stable non-topological solitons, Q-balls, could form in the early universe and comprise the dark matter. It is shown that the inclusion of the effects from gravity-mediation set an upper limit on the size of Q-balls. When in a dense baryonic environment Q-balls grow until reaching this limiting size at which point they fragment into two equal-sized Q-balls. This Q-splitting process will rapidly destroy a neutron star that absorbs even one Q-ball. The new limits on Q-ball dark matter require an ultralight gravitino m_3/2 < keV, nat…
We consider an MSSM extension with anomaly mediation as the source of supersymmetry-breaking, and a U(1) symmetry which solves the tachyonic slepton problem, and introduces both the see-saw mechanism for neutrino masses, and the Higgs mu-term. We compare its spectra with those from so-called minimal anomaly mediated supersymmetry breaking. We find a Standard Model-like Higgs of mass 125 GeV with a gravitino mass of 140 TeV and tan(beta)=16. However, the muon anomalous magnetic moment is 3 sigma away from the experimental value. The model naturally produces a period of hybrid inflation, which c…
We compute the relic abundance of the right-handed sneutrinos in the supersymmetric F_D-term model of hybrid inflation. As well as providing a natural solution to the mu- and gravitino overabundance problems, the F_D-term model offers a new viable candidate to account for the cold dark matter in the Universe: the lightest right-handed sneutrino. In particular, the F_D-term model predicts a new quartic coupling of purely right-handed sneutrinos to the Higgs doublets that thermalizes the sneutrinos and makes them annihilate sufficiently fast to a level compatible with the current cosmic microwav…
The decay of a false vacuum of unbroken B-L symmetry is an intriguing and testable mechanism to generate the initial conditions of the hot early universe. If B-L is broken at the grand unification scale, the false vacuum phase yields hybrid inflation, ending in tachyonic preheating. The dynamics of the B-L breaking Higgs field and thermal processes produce an abundance of heavy neutrinos whose decays generate entropy, baryon asymmetry and gravitino dark matter. We study the phase transition for the full supersymmetric Abelian Higgs model. For the subsequent reheating process we give a detailed…
We present a hybrid RSI/RSII model in which we both solve the hierarchy problem and produce a continuum of KK graviton modes. In this model, four dimensional gravity can be reproduced and the radion mode can be stabilized. We then modify the hybrid gravity model to include SU(2)_L x SU(2)_R x U(1)_(B-L) bulk gauge fields. Electroweak symmetry is broken by the choice of appropriate boundary conditions. By adjusting the size of one region of the extra dimension, we show that the S parameter can be decreased while protecting the rho parameter from corrections. We find that as the S parameter is d…
In general, we can propose the hybrid supersymmetry breakings and hybrid mediations in the Supersymmetric Standard Models (SSMs). In this paper, we study the hybrid mediation for supersymmetry (SUSY) breaking. In particular, we study how to keep the good properties of gravity mediation, gauge mediation, and anomaly mediation, while solve their problems simultaneously. As an example, we consider the anomaly-gravity mediation, where all the supersymmetric particles (sparticles) obtain the SUSY breaking soft terms from the traditional gravity mediation while gauge mediation gives dominant contrib…
Pure gravity mediation (PGM), with two free parameters, is a minimalistic approach to supergravity models, yet is capable of incorporating radiative electroweak symmetry breaking, a Higgs mass in agreement with the experimental measurement, without violating any phenomenological constraints. The model may also contain a viable dark matter candidate in the form of a wino. Here, we extend the minimal model by allowing the $μ$-term to be a free parameter (equivalent to allowing the two Higgs soft masses, $m_1$ and $m_2$, to differ from other scalar masses) which are set by the gravitino mass. In …
We propose a hybrid mediation and hybrid supersymmetry breaking. In particular the RG-invariant anomaly mediation is considered. Together with additional gravity mediation the slepton tachyon problem of anomaly mediation is solved automatically. The special properties are that all of color sparticles masses fall into several TeV region due to the large $m_0$ and $m_{32}$ which are well beyond the scope of current LHC Run II limits. Unlike the gauge mediation, the dark matter candidate is still the lightest neutralino and the correct dark matter relic density can be realized within the framewor…
It is often argued that the minimal supersymmetric standard model has O(100) free parameters and the generic parameter region is already excluded by the null observation of the flavor and CP violating processes as well as the constraints from the LHC experiments. This situation naturally leads us to consider the case where all the dangerous soft supersymmetry breaking terms such as the scalar masses and scalar couplings are absent, while only the unified gaugino mass term and the mu term are non-vanishing at the grand unification scale. We revisit this simple situation taking into account the …
We consider supersymmetric models where gauge mediation provides the dominant contributions to the soft supersymmetry breaking terms while gravity mediation provides sub-dominant yet non-negligible contributions. We further assume that the gravity-mediated contributions are subject to selection rules that follow from a Froggatt-Nielsen symmetry. This class of models constitutes an example of viable and natural non-minimally flavor violating models. The constraints from mixing in the neutral K system imply that the modifications to the Standard Model predictions for mixing in the neutral B_d an…
