Fine tuning in the constrained exceptional supersymmetric standard model

Athron, Peter; Binjonaid, Maien; King, Stephen F.

doi:10.1103/physrevd.87.115023

Cited by 30 publications

(35 citation statements)

References 94 publications

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“…The interaction between the extra singlet superfield, whose vacuum expectation value (VEV) breaks the U(1) ′ , and the two Higgs doublets helps to increase the mass of the SM-like Higgs at the tree level. This contribution is the same as in the next-to-MSSM (NMSSM) [17][18][19][20]. In addition, the SM-like Higgs boson mass is also enhanced by the U(1) ′ D-term contribution [21,22].…”

Section: Introductionmentioning

confidence: 48%

Dark matter in U(1) extensions of the MSSM with gauge kinetic mixing

2017

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The gauge kinetic mixing in general is allowed in models with multiple Abelian gauge groups. In this paper, we investigate the gauge kinetic mixing in the framework of U(1) extensions of the MSSM. It enlarges the viable parameter space, and has an important effect on the particle mass spectrum as well as the Z 2 coupling with matters. The SM-like Higgs boson mass can be enhanced with a nonzero kinetic mixing parameter and the muon g − 2 tension is slightly less severe than in the case of no mixing. We present the results from both benchmark analysis and global parameter scan. Various theoretical and phenomenological constraints have been considered. The recent LHC searches for the Z 2 boson are important for the case of large positive kinetic mixing where the Z 2 coupling is enhanced, and severely constrain scenarios with M Z 2 < 2.8 TeV. The viable dark matter candidate predicted by the model is either the neutralino or the right-handed sneutrino. Cosmological constraints from dark matter searches play a significant role in excluding the parameter space. Portions of the parameter space with relatively low sparticle mass spectrum can be successfully explored in the LHC run-2 as well as future linear colliders and dark matter searches.

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Section: Introductionmentioning

confidence: 48%

Dark matter in U(1) extensions of the MSSM with gauge kinetic mixing

2017

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“…With the current CMS experimental mass limit for the Z in the E 6 SSM of M Z 2.08 TeV [7] it is clear that there is already a significant, perhaps dominant, amount of fine-tuning due to the Z mass limit, and furthermore this source of fine-tuning increasing quadratically with M Z will rapidly overtake the logarithmic fine-tuning due to the stop mass limits, as the experimental mass limits of both types of particles increases in the future. This was first pointed out in [8] and has been discussed quantitatively [9] in the framework of the constrained E 6 SSM [10], where it has been verified that this new source of fine-tuning dominates over all other sources.…”

Section: Introductionmentioning

confidence: 68%

LittleZ′models

2013

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We propose a new class of models called Little Z models in order to reduce the fine-tuning due to the current experimental limits on the Z mass in E 6 inspired supersymmetric models, where the Higgs doublets are charged under the extra U (1) gauge group. The proposed Little Z models allow a lower mass Z due to the spontaneously broken extra U (1) gauge group having a reduced gauge coupling. We show that reducing the value of the extra gauge coupling relaxes the experimental limits, leading to the possibility of low mass Z resonances, for example down to 200 GeV, which may yet appear in LHC searches. Although the source of tree level fine-tuning due to the Z mass is reduced in Little Z models, it typically does so at the expense of increasing the vacuum expectation value of the U (1) -breaking standard model singlet field, reducing the fine-tuning to similar levels to that in the Minimal Supersymmetric Standard Model.

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“…Radiative corrections can accommodate m h 125 GeV but only at the expense of either 1. having top squark masses beyond the TeV scale along with large mixing [29], or else 2. enlarging the MSSM to contain additional contributions to m h [30,31,32]. The first of these possibilities again seems in violation of naturalness limits which according to many studies require mt 1,2 , mb 1 500 GeV [33,34,35,36].…”

Section: Introductionmentioning

confidence: 99%

How conventional measures overestimate electroweak fine-tuning in supersymmetric theory

2013

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The lack of evidence for superparticles at the CERN LHC, along with the rather high value of the Higgs boson mass, has sharpened the perception that what remains of supersymmetric model parameter space suffers a high degree of electroweak fine-tuning (EWFT). We compare three different measures of fine-tuning in supersymmetric models. 1. ∆ HS measures a subset of terms containing large log contributions to m Z (and m h ) that are inevitable in models defined at scales much higher than the electroweak scale. 2. The traditional ∆ BG measures fractional variation in m Z against fractional variation of model parameters and allows for correlations among high scale parameters which are not included in ∆ HS . 3. The model-independent ∆ EW measures how naturally a model can generate the measured value of m Z = 91.2 GeV (or m h ) in terms of weak scale parameters alone. We hypothesize an overarching Ultimate Theory (UTH) wherein the high scale soft terms are all correlated. The UTH might be contained within the more general effective SUSY theories which are popular in the literature. In the case of ∆ HS , EWFT can be grossly overestimated by neglecting additional non-independent terms which lead to large cancellations. In the case of ∆ BG , EWFT can be overestimated by applying the measure to the effective theories instead of to the UTH. The measure ∆ EW allows for the possibility of parameter correlations which should be present in the UTH and, since it is model-independent, provides the same value of EWFT for the effective theories as should occur for the UTH. We find that the well-known mSUGRA/CMSSM model is fine-tuned under all three measures so that it is unlikely to contain the UTH. The non-universal Higgs model NUHM2 appears fine-tuned with ∆ HS,BG 10 3 . But since ∆ EW can be as small as 7 (corresponding to 14% fine-tuning), it may contain the UTH for parameter ranges which allow for low true EWFT. *

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Fine tuning in the constrained exceptional supersymmetric standard model

Cited by 30 publications

References 94 publications

Dark matter in U(1) extensions of the MSSM with gauge kinetic mixing

Dark matter in U(1) extensions of the MSSM with gauge kinetic mixing

LittleZ′models

How conventional measures overestimate electroweak fine-tuning in supersymmetric theory

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