What if supersymmetry breaking unifies beyond the GUT scale?

Abstract

We study models in which soft supersymmetry-breaking parameters of the MSSM become universal at some unification scale, M in , above the GUT scale, M GU T . We assume that the scalar masses and gaugino masses have common values, m 0 and m 1/2 respectively, at M in . We use the renormalization-group equations of the minimal supersymmetric SU(5) GUT to evaluate their evolutions down to M GU T , studying their dependences on the unknown parameters of the SU(5) superpotential. After displaying some generic examples of the evolutions of the soft supersymmetry-breaking parameters, we discuss the effects on physical sparticle masses in some specific examples. We note, for example, that near-degeneracy between the lightest neutralino and the lighter stau is progressively disfavoured as M in increases. This has the consequence, as we show in (m 1/2 , m 0 ) planes for several different values of tan β, that the stau coannihilation region shrinks as M in increases, and we delineate the regions of the (M in , tan β) plane where it is absent altogether. Moreover, as M in increases, the focus-point region recedes to larger values of m 0 for any fixed tan β and m 1/2 . We conclude that the regions of the (m 1/2 , m 0 ) plane that are commonly favoured in phenomenological analyses tend to disappear at large M in .

The super-GUT CMSSM revisited

“…We note that, for m 2 = 0 or even negative, we are able to recover solutions with A 0 = 0. However, when M in > M GUT , one does not find a focus-point region as discussed previously [80][81][82].…”

“…Correspondingly, the super-GUT CMSSM has greater scope for compatibility with the proton stability and m h constraints. We had previously noted [80][81][82] that, for probe even at the 100 TeV collider; see [154], however. On the other hand, the gluino mass can be 10 TeV, which can be probed at the 100 TeV collider [153].…”

“…Note that, if we set M in = M GUT , the above conditions are equivalent to those in the CMSSM. These parameters are evolved down to M GUT using the renormalisation-group equations (RGEs) of the minimal supersymmetric SU(5) GUT, which can be found in [80][81][82][102][103][104], with appropriate changes of notation. During the evolution, the GUT parameters in Eq.…”

“…Fewer studies have been performed for scenarios in which the soft supersymmetry-breaking parameters are universal at some other scale M in = M GUT , which might be either below the GUT scale (so-called sub-GUT or GUT-less scenarios [32,63,[74][75][76]) or above the GUT scale (so-called super-GUT scenarios [77][78][79][80][81][82][83][84]). For example, in our current state of confusion about the possible mechanism of supersymmetry breaking, and specifically in the absence of a convincing dynamical origin at M GUT , one could well imagine that the universality scale M in might lie closer to the Planck or string scale: M in > M GUT .…”

Sparticle mass spectra from SU(5) SUSY GUT models with b − τ Yukawa coupling unification

“…If the scales of the two stages are significantly separated, then one needs to take into account the evolution of the SSB terms above M GU T . Such super-GUT effects can lead to sufficiently different sparticle spectra with interesting phenomenology [9,10,17]: for example, the no-scale scenario can be made compatible with experimental constraints [18]. The breaking pattern (4) may also allow for heavier gluino masses to occur in the range of mg ∼ 0.5 − 1 TeV.…”