Norimi Yokozaki

Implications of the 750 GeV Diphoton Excess in Gaugino Mediation

The 750 GeV diphoton excess reported by ATLAS and CMS indicates the presence of several pairs of the vectorlike matter multiplets around TeV scale. If that is the case, radiative corrections from the

Diphoton excess from hidden U(1) gauge symmetry with large kinetic mixing

SU(3)

Splitting mass spectra and muon g − 2 in Higgs-anomaly mediation

gauge interaction significantly change from those of the minimal supersymmetric standard model, and the infrared-free nature of the gauge interaction leads to characteristic supersymmetry mass spectra: a ratio of a squark mass to the gluino mass, and scalar trilinear couplings are enhanced at the low-energy scale. Consequently, even in gaugino mediation models, the Higgs boson mass of 125 GeV is explained with the fairly light gluino of 2\char21{}3 TeV, which can be accessible at the LHC.

Muon g 2 in anomaly mediated SUSY breaking

Abstract We show that the 750 GeV diphoton excess can be explained by introducing vector-like quarks and hidden fermions charged under a hidden U(1) gauge symmetry, which has a relatively large coupling constant as well as a significant kinetic mixing with U(1) Y . With the large kinetic mixing, the standard model gauge couplings unify around 10 17 GeV , suggesting the grand unified theory without too rapid proton decay. Our scenario predicts events with a photon and missing transverse momentum, and its cross section is related to that for the diphoton excess through the kinetic mixing. We also discuss other possible collider signatures and cosmology, including various ways to evade constraints on exotic stable charged particles. In some cases where the 750 GeV diphoton excess is due to diaxion decays, our scenario also predicts triphoton and tetraphoton signals.

Nambu-Goldstone Boson Hypothesis for Squarks and Sleptons in Pure Gravity Mediation

Abstract We propose a scenario where only the Higgs multiplets have direct couplings to a supersymmetry (SUSY) breaking sector. The standard model matter multiplets as well as the gauge multiples are sequestered from the SUSY breaking sector; therefore, their masses arise via anomaly mediation at the high energy scale with a gravitino mass of ∼ 100 TeV . Due to renormalization group running effects from the Higgs soft masses, the masses of the third generation sfermions become O ( 10 ) TeV at the low energy scale, while the first and second generation sfermion masses are O ( 0.1 - 1 ) TeV , avoiding the tachyonic slepton problem and flavor changing neutral current problem. With the splitting mass spectrum, the muon g − 2 anomaly is explained consistently with the observed Higgs boson mass of 125 GeV. Moreover, the third generation Yukawa couplings are expected to be unified in some regions.

Gravitational waves from domain walls and their implications

A bstractMotivated by two experimental facts, the muon g − 2 anomaly and the observed Higgs boson mass around 125 GeV, we propose a simple model of anomaly mediation, which can be seen as a generalization of mixed modulus-anomaly mediation. In our model, the discrepancy of the muon g − 2 and the Higgs boson mass around 125 GeV are easily accommodated. The required mass splitting between the strongly and weakly interacting SUSY particles are naturally achieved by the contribution from anomaly mediation. This model is easily consistent with SU(5) or SO(10) grand unified theory.

Enhanced axion–photon coupling in GUT with hidden photon

A bstractWe point out that a hypothesis of squarks and sleptons being Nambu-Goldstone (NG) bosons is consistent with pure gravity mediation or minimal split supersymmetry (SUSY). As a concrete example, we consider a SUSY E7/SU(5) × U(1)3 non-linear sigma model in the framework of pure gravity mediation. The model accommodates three families of the quark and lepton chiral multiplets as (pseudo) NG multiplets of the Kähler manifold, which may enable us to understand the origin and number of the families. We point out that squarks in the first and second generations are likely to be as light as a few TeV if the observed baryon asymmetry is explained by the thermal leptogenesis; therefore, these colored particles can be discovered at the LHC Run-2 or at the high luminosity LHC.

Muon g − 2 in MSSM gauge mediation revisited

Abstract We evaluate the impact of domain-wall annihilation on the currently ongoing and planned gravitational wave experiments, including a case in which domain walls experience a frictional force due to interactions with the ambient plasma. We show the sensitivity reach in terms of physical parameters, namely, the wall tension and the annihilation temperature. We find that a Higgs portal scalar, which stabilizes the Higgs potential at high energy scales, can form domain walls whose annihilation produces a large amount of gravitational waves within the reach of the advanced LIGO experiment (O5). Domain wall annihilation can also generate baryon asymmetry if the scalar is coupled to either SU(2)L gauge fields or the ( B − L ) current. This is a variant of spontaneous baryogenesis, but it naturally avoids the isocurvature constraint due to the scaling behavior of the domain-wall evolution. We delineate the parameter space where the domain-wall baryogenesis works successfully and discuss its implications for the gravitational wave experiments.

An extended gauge mediation for muon

Abstract We show that the axion coupling to photons can be enhanced in simple models with a single Peccei–Quinn field, if the gauge coupling unification is realized by a large kinetic mixing χ = O ( 0.1 ) between hypercharge and unbroken hidden U(1)H. The key observation is that the U(1)H gauge coupling should be rather strong to induce such large kinetic mixing, leading to enhanced contributions of hidden matter fields to the electromagnetic anomaly. We find that the axion–photon coupling is enhanced by about a factor of 10–100 with respect to the GUT-axion models with E / N = 8 / 3 .

(g-2)

Abstract The Higgs boson of 125 GeV requires large stop masses, leading to the large μ-parameter in most cases of gauge mediation. On the other hand, the explanation for the muon g − 2 anomaly needs small slepton and neutralino/chargino masses. Such disparity in masses may be obtained from a mass splitting of colored and non-colored messenger fields. However, even if the required small slepton and neutralino/chargino masses are realized, all parameter regions consistent with the muon g − 2 are excluded by the recent updated ATLAS result on the wino search in the case that the messenger fields are in 5 + 5 ¯ representations of S U ( 5 ) . It is also revealed that the messenger fields in 10 + 10 ‾ or 24 representation can not explain the muon g − 2 anomaly. We show, giving a simple example model, that the above confliction is solved if there is an additional contribution to the Higgs soft mass which makes the μ-parameter small. We also show that the required Higgs B-term for the electroweak symmetry breaking is consistently generated by radiative corrections from gaugino loops.