Theoretical constraints on supersymmetric models: Perturbative unitarity vs. vacuum stability

Abstract The superpotential in four-dimensional heterotic effective theories contains terms arising from holomorphic Chern-Simons invariants associated to the gauge and tangent bundles of the compactification geometry. These effects are crucial for a number of key features of the theory, including vacuum stability and moduli stabilization. Despite their importance, few tools exist in the literature to compute such effects in a given heterotic vacuum. In this work we present new techniques to explicitly determine holomorphic Chern-Simons invariants in heterotic string compactifications. The key technical ingredient in our computations are real bundle morphisms between the gauge and tangent bundles. We find that there are large classes of examples, beyond the standard embedding, where the Chern-Simons superpotential vanishes. We also provide explicit examples for non-flat bundles where it is non-vanishing and non-integer quantized, generalizing previous results for Wilson lines.

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Exploring color-octet scalar parameter space in minimal R-symmetric models

Journal of High Energy Physics ◽

10.1007/jhep11(2020)024 ◽

2020 ◽

Vol 2020 (11) ◽

Cited By ~ 1

Author(s):

Linda M. Carpenter ◽

Taylor Murphy ◽

Matthew J. Smylie

Keyword(s):

Large Hadron Collider ◽

Parameter Space ◽

Branching Fractions ◽

Hadron Collider ◽

Collider Phenomenology ◽

Decay Channels ◽

Color Octet ◽

Supersymmetric Models ◽

Three Body ◽

Displaced Vertex

Abstract In this work we study the collider phenomenology of color-octet scalars (sgluons) in minimal supersymmetric models endowed with a global continuous R symmetry. We systematically catalog the significant decay channels of scalar and pseudoscalar sgluons and identify novel features that are natural in these models. These include decays in nonstandard diboson channels, such as to a gluon and a photon; three-body decays with considerable branching fractions; and long-lived particles with displaced vertex signatures. We also discuss the single and pair production of these particles and show that they can evade existing constraints from the Large Hadron Collider, to varying extents, in large regions of reasonable parameter space. We find, for instance, that a 725 GeV scalar and a 350 GeV or lighter pseudoscalar can still be accommodated in realistic scenarios.

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Vacuum stability and symmetry breaking in left-right symmetric model

Journal of High Energy Physics ◽

10.1007/jhep12(2019)137 ◽

2019 ◽

Vol 2019 (12) ◽

Cited By ~ 2

Author(s):

Garv Chauhan

Keyword(s):

Symmetry Breaking ◽

Symmetric Model ◽

Vacuum Stability

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Neutrino masses, vacuum stability and quantum gravity prediction for the mass of the top quark

Journal of High Energy Physics ◽

10.1007/jhep01(2021)180 ◽

2021 ◽

Vol 2021 (1) ◽

Author(s):

Guillem Domènech ◽

Mark Goodsell ◽

Christof Wetterich

Keyword(s):

Quantum Gravity ◽

Top Quark ◽

Quark Mass ◽

Scalar Potential ◽

Planck Scale ◽

Neutrino Masses ◽

Top Quark Mass ◽

Vacuum Stability ◽

Intermediate Scale ◽

Yukawa Couplings

Abstract A general prediction from asymptotically safe quantum gravity is the approximate vanishing of all quartic scalar couplings at the UV fixed point beyond the Planck scale. A vanishing Higgs doublet quartic coupling near the Planck scale translates into a prediction for the ratio between the mass of the Higgs boson MH and the top quark Mt. If only the standard model particles contribute to the running of couplings below the Planck mass, the observed MH∼ 125 GeV results in the prediction for the top quark mass Mt∼ 171 GeV, in agreement with recent measurements. In this work, we study how the asymptotic safety prediction for the top quark mass is affected by possible physics at an intermediate scale. We investigate the effect of an SU(2) triplet scalar and right-handed neutrinos, needed to explain the tiny mass of left-handed neutrinos. For pure seesaw II, with no or very heavy right handed neutrinos, the top mass can increase to Mt ∼ 172.5 GeV for a triplet mass of M∆ ∼ 108GeV. Right handed neutrino masses at an intermediate scale increase the uncertainty of the predictions of Mt due to unknown Yukawa couplings of the right-handed neutrinos and a cubic interaction in the scalar potential. For an appropriate range of Yukawa couplings there is no longer an issue of vacuum stability.

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