Abstract
We consider the effects of non-universalities among sfermion generations in models of Pure Gravity Mediation (PGM). In PGM models and in many models with strongly stabilized moduli, the gravitino mass may be O(100) TeV, whereas gaugino masses, generated through anomalies at 1-loop, remain relatively light O(1) TeV. In models with scalar mass universality, input scalar masses are generally very heavy (m_0 \simeq m_{3/2}) resulting in a mass spectrum resembling that in split supersymmetry. However, if one adopts a no-scale or partial no-scale structure for the K\"ahler manifold, sfermion masses may vanish at the tree level. It is usually assumed that the leading order anomaly mediated contribution to scalar masses appears at 2-loops. However, there are at least two possible sources for 1-loop scalar masses. These may arise if Pauli-Villars fields are introduced as messengers of supersymmetry breaking. We consider the consequences of a spectrum in which the scalar masses associated with the third generation are heavy (order m_{3/2}) with 1-loop scalar masses for the first two generations. A similar spectrum is expected to arise in GUT models based on E_7/SO(10) where the first two generations of scalars act as pseudo-Nambu-Goldstone bosons. Explicit breaking of this symmetry by the gauge couplings then generates one-loop masses for the first two generations. In particular, we show that it may be possible to reconcile the g_mu - 2 discrepancy with potentially observable scalars and gauginos at the LHC.
Highlights
The mass of the recently discovered Higgs boson [1,2] is light enough that it can be accommodated in supersymmetry, it is near the upper limit of simple models like the CMSSM [3,4,5,6,7,8,9,10,11,12,13]. This large Higgs mass and the lack of a e-mail: jlevans@umn.edu evidence for supersymmetric particles at the LHC [14,15,16,17] have put severe constraints on the simplest models of supersymmetry [18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35,36,37,38,39,40] including the CMSSM. Since both the LHC constraints on the superpartners and the observed Higgs mass favor heavier sfermion masses [14,15,16,17], it could be that nature does have a mass splitting among the supersymmetric particles as is the case in split supersymmetry [41,42,43,44,45], pure gravity mediation (PGM) [46,47,48,49,50,51], and models with strongly stabilized moduli [52,53,54,55,56,57,58]
Simple models like PGM have many advantages, there are some drawbacks to heavy sfermions
The deviation in (g − 2)μ has little hope of being explained, in this case. Since both of these experimental difficulties hinge on the masses of the first two generations, while the Higgs mass depends primarily on the third generation masses, there may be hope of simultaneously getting all of these nice features
Summary
Since both the LHC constraints on the superpartners and the observed Higgs mass favor heavier sfermion masses [14,15,16,17], it could be that nature does have a mass splitting among the supersymmetric particles as is the case in split supersymmetry [41,42,43,44,45], pure gravity mediation (PGM) [46,47,48,49,50,51], and models with strongly stabilized moduli [52,53,54,55,56,57,58]. In the case of full scalar mass universality, the theory can be described in terms of two free parameters, the gravitino mass, m3/2 and tan β the ratio of the Higgs vacuum expectation values These models placed a rather strict constraint on tan β = 1.7–2.5. A similar suppression of the first and second generation sfermion masses can be realize from a no-scale-like geometry for the Kähler potential [79,80] This geometry can arise from a brane separation where on one brane we have the SUSY breaking fields as well as the Higgs boson and third generation fields and on the other we have the first and second generations fields. In the case of no-scale-like boundary conditions this can be accomplished if the Pauli–Villars fields, which regularize the low-scale theory, interact with supersymmetry breaking generating a one-loop soft masses [83,84].
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