Complementarity of dark matter searches in the phenomenological MSSM

The idea of "Natural SUSY", understood as a supersymmetric scenario where the fine-tuning is as mild as possible, is a reasonable guide to explore supersymmetric phenomenology. In this paper, we re-examine this issue in the context of the MSSM including several improvements, such as the mixing of the fine-tuning conditions for different soft terms and the presence of potential extra fine-tunings that must be combined with the electroweak one. We give tables and plots that allow to easily evaluate the fine-tuning and the corresponding naturalness bounds for any theoretical model defined at any high-energy (HE) scale. Then, we analyze in detail the complete fine-tuning bounds for the unconstrained MSSM, defined at any HE scale. We show that Natural SUSY does not demand light stops. Actually, an average stop mass below 800 GeV is disfavored, though one of the stops might be very light. Regarding phenomenology, the most stringent upper bound from naturalness is the one on the gluino mass, which typically sets the present level fine-tuning at O(1%). However, this result presents a strong dependence on the HE scale. E.g. if the latter is 10 7 GeV the level of fine-tuning is ∼ four times less severe. Finally, the most robust result of Natural SUSY is by far that Higgsinos should be rather light, certainly below 700 GeV for a fine-tuning of O(1%) or milder. Incidentally, this upper bound is not far from 1 TeV, which is the value required if dark matter is made of Higgsinos.

Section: Jhep06(2015)070mentioning

confidence: 99%

What is a natural SUSY scenario?

Casas

Moreno

Robles

et al. 2015

“…Several groups have advocated the use of the pMSSM for interpretation of LHC results [33][34][35][36][37][38][39][40][41][42][43][44][45][46][47][48][49][50][51][52]. Most of these studies use estimated experimental efficiencies and acceptances for pMSSM points, and compare them to the model-independent limits from a selection of LHC searches to constrain the pMSSM parameter space.…”

Section: Jhep10(2015)134mentioning

confidence: 99%

Summary of the ATLAS experiment’s sensitivity to supersymmetry after LHC Run 1 — interpreted in the phenomenological MSSM

Aad

Bergeås

Brenner

et al. 2015

100

169

A summary of the constraints from the ATLAS experiment on R-parityconserving supersymmetry is presented. Results from 22 separate ATLAS searches are considered, each based on analysis of up to 20.3 fb −1 of proton-proton collision data at centre-of-mass energies of √ s = 7 and 8 TeV at the Large Hadron Collider. The results are interpreted in the context of the 19-parameter phenomenological minimal supersymmetric standard model, in which the lightest supersymmetric particle is a neutralino, taking into account constraints from previous precision electroweak and flavour measurements as well as from dark matter related measurements. The results are presented in terms of constraints on supersymmetric particle masses and are compared to limits from simplified models. The impact of ATLAS searches on parameters such as the dark matter relic density, the couplings of the observed Higgs boson, and the degree of electroweak fine-tuning is also shown. Spectra for surviving supersymmetry model points with low fine-tunings are presented. The ATLAS collaboration 58 Keywords: Hadron-Hadron Scattering IntroductionDuring the first run of the Large Hadron Collider (LHC), the ATLAS [1] and CMS [2] Collaborations performed a wide range of searches for supersymmetry (SUSY) [3][4][5][6][7][8][9][10][11], using proton-proton (pp) collision data at centre-of-mass energies ( √ s) of 7 and 8 TeV. SUSY, a theoretically favoured framework for extending the Standard Model (SM), is able to address some of its unanswered questions, particularly the hierarchy problem [12][13][14][15], which is related to the fine-tuning needed to obtain the correct mass for the observed Higgs boson. SUSY can also provide credible dark matter candidates [16,17] and can improve the unification of the electroweak and strong interactions [18][19][20][21][22][23][24][25][26].The minimal supersymmetric extension of the Standard Model (MSSM) [27][28][29][30][31] predicts partners for each of the SM states. It predicts a pair of scalar partners -one for each fermion chirality -for each of the SM quarks and leptons. These spin-zero partner particles are known as squarks (q) and sleptons (˜ ) respectively. In the first two generations the pair of chiral partners is largely unmixed, so the mass states can be labelledẽ L andẽ R , where the L and R subscripts denote the scalar partners of the left-and right-handed Standard Model fermion states respectively. In the third generation of quarks and leptons the mixing between the scalars is larger, and the mixed states are labelled by their mass indices e.g.t 1 and t 2 , wheret 1 is lighter by construction. Each state in the SM gluon colour octet has a spinhalf partner known as a gluinog. There are a total of eight spin-half partners of the electroweak gauge and Higgs bosons: the neutral bino (superpartner of the U(1) gauge field); the winos, which are a charged pair and a neutral particle (superpartners of the W bosons of the SU(2) L gauge fields); and the Higgsinos, which are two neutral particles and a charged pai...

“…Large |µ| is often considered in works involving global analyses of parameter space for unified models like CMSSM [80]. It has also been explored in pMSSM related studies [81] or a similar analysis involving vacuum stability as in ref. [82].…”

Section: Jhep11(2014)161mentioning

confidence: 99%

Exploring MSSM for charge and color breaking and other constraints in the context of Higgs@125 GeV

Chattopadhyay

Dey

2014

Exploring MSSM parameter space after the discovery of Higgs Boson at 125 GeV naturally demands large top-squark mixing or large trilinear coupling parameter A t in particular, so as to avoid excessively heavy squark, specially for the universal models like CMSSM. We study stability of electroweak symmetry breaking vacua in possible presence of deeper charge-color symmetry breaking minima within MSSM. Besides stable vacua, we consider scenarios characterized by the presence of global CCB minima, with SM like charge and color conserving vacuum, having stability over cosmologically large lifetime (long-lived states). We allow vacuum expectation values for both stop as well as sbottom fields, since these belong to the third generation of sfermions with larger Yukawa couplings that have immediate effect on the tunneling time. Moreover, for large µ regions, radiative corrections to Higgs boson mass from bottom-squark loop is quite significant. Regions of MSSM parameters space become viable for large A t and large µ zones which are generically excluded via the traditional analytical CCB constraints. For a large value of tan β, safe vacua associated with large values of |µ| and |A t | are predominantly long-lived and may be associated with relatively light stop masses. We also identify low µ regions associated with long-lived states. Both the above zones can be friendly to muon g − 2 constraint. We also impose constraints from Br(B → X s γ) and Br(B s → µ + µ − ). We do the analysis for a moderate and a large tan β. We choose an example parameter point in the gaugino mass plane of M 1 , M 2 that satisfies the dark matter constraints, basically a decoupled sector with respect to CCB.