arXiv subjects
Publications and source records attributed to Kazuya Yonekura.
We demonstrate that the supersymmetry is dynamically broken in the four-dimensional SU(N) gauge theory coupled to a strongly-coupled superconformal theory T_N. This is a direct generalization of the model of supersymmetry breaking on deformed moduli space in supersymmetric QCD with an SU(2) gauge group.
The coefficient tau_{RR} of the two-point function of the superconformal U(1)_R currents of N=2 SCFTs in three-dimensions is recently shown to be obtained by differentiating the partition function on a squashed three-sphere with respect to the squashing parameter. With this method, we compute the tau_{RR} for N=2 Wess-Zumino models and SQCD numerically for small number of flavors and analytically in the large number limit. We study the behavior of tau_{RR} under an RG flow by adding superpotentials to the theories. While the tau_{RR} decreases for the gauge theories, we find an N=2 Wess-Zumino model whose tau_{RR} increases along the RG flow. Since tau_{RR} is proportional to the coefficient C_T of the two-point correlation function of the stress-energy tensors for N=2 superconformal field theories, this rules out the possibility of C_T being a measure of the degrees of freedom which monotonically decreases along RG flows in three-dimensions.
We study perturbative behavior of free energies on a d-dimensional sphere S^d for theories with marginal interactions. The free energies are interpreted as the "dilaton effective action" with the dilaton having a nontrivial background vacuum expectation value. We compute the dependence of the free energies on the radius of the sphere by using dimensional regularization. It is shown that the first (second) derivative of the free energies in odd (even) dimensions with respect to the radius of the sphere are proportional to the square of the beta functions of coupling constants. The result is consistent with the c, F and a-theorems in two, three, four and six dimensions. The result is also used to rule out a large class of scale invariant theories which are not conformally invariant.
We consider low scale gauge mediation models with a very light gravitino m_{3/2}~16 eV, in the light of recent experimental hints on the Higgs boson mass. The light gravitino is very interesting since there is no gravitino over-production problem, but it seems difficult to explain the Higgs boson mass of ~125 GeV. This is because of the conflict between the light gravitino mass and heavy SUSY particle masses needed for producing the relatively heavy Higgs boson mass. We consider two possible extensions in this paper: a singlet extension of the Higgs sector, and strongly coupled gauge mediation. We show that there is a large parameter space, in both scenarios, where the Higgs boson mass of ~125 GeV is explained without any conflict with such a very light gravitino.
Naive dimensional analysis (NDA) is a widely used ansatz to estimate coupling constants among composite states emerging from dynamics of a strongly coupled gauge theory. However, the validity of NDA is still unclear because of the difficulty in calculating these quantities in strongly coupled theories. We examine the NDA ansatz using gauge/string duality, by estimating glueball coupling constants from gravitational description. The NDA scaling rule for coupling constants of some types of glueballs is verified and extended by both generic estimation and numerical calculations. The scaling rule verified in this article can be applied to some class of quiver gauge theories as well, not just to gauge theories with a single gauge group $SU(N_c)$.
The trace anomaly of the energy-momentum tensor is usually quoted in the form which is proportional to the beta function of the theory. However, there are in general many definitions of gauge couplings depending on renormalization schemes, and hence many beta functions. In particular, N=1 supersymmetric pure Yang-Mills has the holomorphic gauge coupling whose beta function is one-loop exact, and the canonical gauge coupling whose beta function is given by the Novikov-Shifman-Vainshtein-Zakharov beta function. In this paper, we study which beta function should appear in the trace anomaly in N=1 pure Yang-Mills. We calculate the trace anomaly by employing the N=4 regularization of N=1 pure Yang-Mills. It is shown that the trace anomaly is given by one-loop exact form if the composite operator appearing in the trace anomaly is renormalized in a preferred way. This result gives the simplest resolution to the anomaly puzzle in N=1 pure Yang-Mills. The most important point is to examine in which scheme the quantum action principle is valid, which is crucial in the derivation of the trace anomaly.
We show that the upper bound on the lightest Higgs mass in the MSSM is relaxed by introducing a singlet which couples to the Higgs fields, even at a large tan beta region, preferable for explaining the muon anomalous magnetic moment. In the models of a singlet extension, it is known that the upper bound is relaxed by a tree-level contribution, especially at small tan beta region. For large tan beta, however, the requirement for the perturbativity on the singlet-Higgs coupling up to the GUT scale prevents the lightest Higgs from obtaining a large tree-level mass. We construct an explicit UV complete model which allows large singlet-Higgs coupling at low energy without disturbing the perturbativity. The UV completion can be applied for any singlet extension of the MSSM. Moreover, we point out that the radiative correction from the singlet-Higgs coupling becomes dominant, and the lightest Higgs mass can be easily as heavy as 130 GeV if this coupling is large enough even for large tan beta.
We study the Coulomb phase of N=1 SU(2)^3 gauge theory coupled to one trifundamental field, and generalizations thereof. The moduli space of vacua is always one-dimensional with multiple unbroken U(1) fields. We find that the N=1 Seiberg-Witten curve which encodes the U(1) couplings is given by the double cover of a Riemann surface branched at the poles and the zeros of a meromorphic function.
Recently, the CDF collaboration reports an anomaly in dijet mass distribution in association with a lepton and missing energy. We discuss a possibility that the origin of the lepton and missing energy comes not from a W boson but a new boson particle, which is also responsible for the dijet mass peak. We show that such a situation can be realized in the framework of the minimal supersymmetric standard model and the dijet anomaly can be explained.
We consider the simplest class of the R-invariant gauge mediation model with the gravitino mass in the one to ten keV range. We show that the entropy production from the supersymmetry breaking sector makes the gravitino into a warm dark matter candidate. We also discuss that the gluino mass can be lighter than the wino mass even when the messenger sector satisfies the GUT relations at the GUT scale.
Recently, Komargodski and Seiberg have proposed a new type of supercurrent multiplet which contains the energy-momentum tensor and the supersymmetry current consistently. In this paper we study quantum properties of the supercurrent in renormalizable field theories. We point out that the new supercurrent gives a quite simple resolution to the classic problem, called the anomaly puzzle, that the Adler-Bardeen theorem applied to an R-symmetry current is inconsistent with all order corrections to $β$ functions. We propose an operator equation for the supercurrent in all orders of perturbation theory, and then perform several consistency checks of the equation. The operator equation we propose is consisitent with the one proposed by Shifman and Vainshtein, if we take some care in interpreting the meaning of non-conserved currents.
A large class of non-minimal gauge mediation models, such as (semi-)direct gauge mediation, predict a hierarchy between the masses of the supersymmetric standard model gauginos and those of scalar particles. We perform a comprehensive study of these non-minimal gauge mediation models, including mass calculations in semi-direct gauge mediation, to illustrate these features, and discuss the phenomenology of the models. We point out that the cosmological gravitino problem places stringent constraints on mass splittings, when the Bino is the NLSP. However, the GUT relation of the gaugino masses is broken unlike the case of minimal gauge mediation, and an NLSP other than the Bino (especially the gluino NLSP) becomes possible, relaxing the cosmological constraints. We also discuss the collider signals of the models.
If the supersymmetry (SUSY) is a solution to the hierarchy problem, it is puzzling that any SUSY particle has not been discovered yet. We show that there is a low-scale conformal gauge mediation model which contains all necessary ingredients, i.e. not only a SUSY-breaking dynamics and a gauge mediation mechanism, but also a candidate for the dark matter. The model has only one free parameter, that is, the mass for messengers. In this model, the dark matter is provided by a composite particle in the SUSY-breaking sector, and the observed value of the dark matter density uniquely fixes the mass of messengers at the order of 10^2 TeV. Then, the sfermion and gaugino masses are fixed to be of order 10^2~10^3 GEV without any arbitrariness, thus the SUSY particles are expected not to be discovered at the Tevatron or LEP, while having a discovery possibility at the LHC.
In a recent work, a model of gauge mediation with sequestered supersymmetry (SUSY) breaking was proposed. In this model, the mass of the gravitino is O(100) GeV without causing the flavor-changing neutral-current problem. In contrast to traditional gauge mediation, the gravitino is not the lightest SUSY particle and the neutralino is the candidate of the dark matter. In this paper, we investigate phenomenological aspects of this model and discuss the possibility of the direct detection of the dark matter. In particular, we focus on the light neutralino case and find that the light-Higgsino scenario such as the focus point is interesting, taking account of the recent CDMS result.
In a class of direct gauge mediation with a perturbatively stable SUSY breaking vacuum, gaugino masses vanish at the leading order of SUSY breaking F-term. We study the allowed parameter space of the gauge mediation models. By imposing a Tevatron bound on the lightest chargino mass m_{{\tilde χ}^\pm_1} > 270 GeV and a warm dark-matter mass bound on the light gravitino mass m_{3/2} < 16 eV, we find that almost all the parameter space is excluded. Near future experiments may completely exclude, or possibly discover, the scenario.
Direct gauge mediation models using the Intriligator-Seiberg-Shih (ISS) metastable vacua suffer from the Landau pole problem of the standard model gauge couplings and the existence of R symmetry forbidding gaugino masses. These problems may be solved by using the recently proposed SUSY breaking models in a conformal window of the vector-like $SU(N_C)$ gauge theory with gauge singlets. In this paper we propose a model of gauge mediation based on the SUSY-breaking model in the conformal window, and study the dynamics for the SUSY breaking. In the model, there are massive vector-like bifundamental fields charged under both $SU(N_C)$ and the standard model gauge group, and our model can be regarded as a semi-direct gauge mediation model. The color number $N_C$ can be small to avoid the Landau pole problem, and the R symmetry is also broken under a reasonable assumption on the strong dynamics of the model. The model possesses only one free parameter, and the gaugino and sfermion masses are naturally of the same order.
We propose a mechanism for relaxing a constraint on the number of messengers in low-scale gauge mediation models. The Landau pole problem for the standard-model gauge coupling constants in the low-scale gauge mediation can be circumvented by using our mechanism. An essential ingredient is a large positive anomalous dimension of messenger fields given by a large Yukawa coupling in a conformal field theory at high energies. The positive anomalous dimension reduces the contribution of the messengers to the beta function of the standard-model gauge couplings.
A new class of models of dynamical supersymmetry breaking is proposed. The models are based on SU(N_C) gauge theories with N_F(<N_C) flavors of quarks and singlets. Dynamically generated superpotential exibits runaway behavior. By embedding the models into conformal field theories at high energies, the runaway potential is stabilized by strong quantum corrections to the Kahler potential. The quantum corrections are large but nevertheless can be controlled due to superconformal symmetry of the theories.