Jason L. Evans

Relatively heavy Higgs boson in more generic gauge mediation

Abstract We discuss gauge mediation models where the doublet messengers and Higgs doublets are allowed to mix through a “charged” coupling. The charged coupling replaces messenger parity as a means of suppressing flavor changing neutral currents without introducing any unwanted CP violation. As a result of this mixing between the Higgs doublets and the messengers, relatively large A-terms are generated at the messenger scale. These large A-terms produce a distinct weak scale mass spectrum. Particularly, we show that the lightest Higgs boson mass is enhanced and can be as heavy as 125 GeV for a gluino mass as light as 2 TeV. We also show that the stops are heavier than that predicted by conventional gauge mediation models. It is also shown that these models have a peculiar slepton mass spectrum.

The moduli and gravitino (non)-problems in models with strongly stabilized moduli

In gravity mediated models and in particular in models with strongly stabilized moduli, there is a natural hierarchy between gaugino masses, the gravitino mass and moduli masses: m 1/2 ≪ m 3/2 ≪ m�. Given this hierarchy, we show that 1) moduli problems associated with excess entropy production from moduli decay and 2) problems associated with moduli/gravitino decays to neutralinos are non-existent. Placed in an inflationary context, we show that the amplitude of moduli oscillations are severely limited by strong stabilization. Moduli oscillations may then never come to dominate the energy density of the Universe. As a consequence, moduli decay to gravitinos and their subsequent decay to neutralinos need not overpopulate the cold dark matter density.

Non-universalities in pure gravity mediation

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 (m3/2≳300 TeV) and a limited range in tanβ≃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 generalization allows us to greatly increase the allowed range in tanβ and it allows one to find viable solutions with lower m3/2. The latter is important if we hope to find a low energy signal from gluinos. Some special cases of these non-universalities are suggestive of Higgs bosons as Nambu–Goldstone bosons or a partial no-scale structure for the Higgs doublets. Thus, we probe signatures at the weak scale and structures at the GUT and/or Planck scale.

Scenarios for gluino coannihilation

A bstractWe study supersymmetric scenarios in which the gluino is the next-to-lightest supersymmetric particle (NLSP), with a mass sufficiently close to that of the lightest supersymmetric particle (LSP) that gluino coannihilation becomes important. One of these scenarios is the MSSM with soft supersymmetry-breaking squark and slepton masses that are universal at an input GUT renormalization scale, but with non-universal gaugino masses. The other scenario is an extension of the MSSM to include vector-like supermultiplets. In both scenarios, we identify the regions of parameter space where gluino coannihilation is important, and discuss their relations to other regions of parameter space where other mechanisms bring the dark matter density into the range allowed by cosmology. In the case of the non-universal MSSM scenario, we find that the allowed range of parameter space is constrained by the requirement of electroweak symmetry breaking, the avoidance of a charged LSP and the measured mass of the Higgs boson, in particular, as well as the appearance of other dark matter (co)annihilation processes. Nevertheless, LSP masses mχ ≲ 8 TeV with the correct dark matter density are quite possible. In the case of pure gravity mediation with additional vector-like supermultiplets, changes to the anomaly- mediated gluino mass and the threshold effects associated with these states can make the gluino almost degenerate with the LSP, and we find a similar upper bound.

Naturalizing Supersymmetry with a Two-Field Relaxion Mechanism

A bstractWe present a supersymmetric version of a two-field relaxion model that naturalizes tuned versions of supersymmetry. This arises from a relaxion mechanism that does not depend on QCD dynamics and where the relaxion potential barrier height is controlled by a second axion-like field. During the cosmological evolution, the relaxion rolls with a nonzero value that breaks supersymmetry and scans the soft supersymmetric mass terms. Electroweak symmetry is broken after the soft masses become of order the supersymmetric Higgs mass term and causes the relaxion to stop rolling for superpartner masses up to ∼ 109 GeV. This can explain the tuning in supersymmetric models, including split-SUSY models, while preserving the QCD axion solution to the strong CP problem. Besides predicting two very weakly-coupled axion-like particles, the supersymmetric spectrum may contain an extra Goldstino, which could be a viable dark matter candidate.

Universality in pure gravity mediation with vector multiplets

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

The Lightest Higgs Boson Mass in the MSSM with Strongly Interacting Spectators

\tan \beta \approx 2-3

The super-GUT CMSSM revisited

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

SU(5) Grand Unification in Pure Gravity Mediation

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Low-scale D -term inflation and the relaxion mechanism

and