Muon g − 2 and related phenomenology in constrained vector-like extensions of the MSSM

Journal of High Energy Physics, May 2017

We analyze two minimal supersymmetric constrained models with low-energy vector-like matter preserving gauge coupling unification. In one we add to the MSSM spectrum a pair \( \mathbf{5}+\overline{\mathbf{5}} \) of SU(5), in the other a pair \( \mathbf{10}+\overline{\mathbf{10}} \). We show that the muon g−2 anomaly can be explained in these models while retaining perturbativity up to the unification scale, satisfying electroweak and flavor precision tests and current LHC data. We examine also some related phenomenological features of the models, including Higgs mass, fine-tuning, dark matter and several LHC signatures. We stress that, at least for the \( \mathbf{5}+\overline{\mathbf{5}} \) model, the parameter space consistent with g − 2 is entirely in reach of the LHC with a moderate increase in luminosity with respect to the current data set.

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Muon g − 2 and related phenomenology in constrained vector-like extensions of the MSSM

Received: February 2 and related phenomenology in constrained vector-like extensions of the MSSM Arghya Choudhury 0 1 3 4 6 7 8 9 Luc Darme 0 1 3 5 6 7 8 9 Leszek Roszkowski 0 1 3 5 4 6 7 8 9 Enrico Maria Sessolo 0 1 3 5 6 7 8 9 Sebastian Trojanowski 0 1 2 3 5 6 7 8 9 Open Access 0 1 3 6 7 8 9 c The Authors. 0 1 3 6 7 8 9 0 University of Manchester 1 Hicks Building, She eld S3 7RH, U.K 2 Department of Physics and Astronomy, University of California 3 University of She eld 4 Consortium for Fundamental Physics, Department of Physics and Astronomy 5 National Centre for Nuclear Research 6 2 is entirely in reach of the LHC 7 Frederick Reines Hall , Irvine, CA 92697 , U.S.A 8 Hoz_a 69 , 00-681 Warsaw , Poland 9 Schuster Building , Manchester, M13 9PL, U.K We analyze two minimal supersymmetric constrained models with low-energy vector-like matter preserving gauge coupling uni cation. In one we add to the MSSM spectrum a pair 5 + 5 of SU(5), in the other a pair 10 + 10. We show that the muon 2 anomaly can be explained in these models while retaining perturbativity up to the uni cation scale, satisfying electroweak and We examine also some related phenomenological features of the models, including Higgs ne-tuning, dark matter and several LHC signatures. We stress that, at least for the 5 + 5 model, the parameter space consistent with g with a moderate increase in luminosity with respect to the current data set. Supersymmetry Phenomenology 1 Introduction 2 The models The 5-plet LD model The 10-plet QUE model 2.3 Boundary conditions 3 Low energy phenomenology 3.1 3.2 3.3 Gaugino and scalar mass spectra Bounds from perturbativity and physicality 3.5 Bounds from electroweak precision tests 4 The (g 2) anomaly in VL models 5 Numerical results Muon g-2 benchmark points Dark matter and direct detection 6 Summary and conclusions A Soft Lagrangian and mass matrices C Approximate formulas for (g 2) D Scan range E Collider constraints B Leptonic rotation matrices and electroweak precision observables Introduction The lack of convincing signals of beyond the Standard Model (BSM) physics at the LHC has severely constrained many scenarios for new physics. More precisely, the idea, mainly motivated by the hierarchy problem, that BSM physics should be found around or just above the electroweak symmetry breaking (EWSB) scale seems to be now under strain in many frameworks, including low scale supersymmetry (SUSY). Direct searches for the sparticles of the Minimal Supersymmetric Standard Model (MSSM) by CMS [1{4] and ATLAS [5{8] have now pushed the gluino mass bound to 1.7{1.9 TeV for most choices of spectrum and decay cascade,1 each of the light generation squarks to 1 TeV and above, and the lightest stop to 700{800 GeV and above. On the other hand, SUSY masses at, or actually above, the 1 TeV range show the greatest consistency with the Higgs boson mass at 125 GeV, especially in models de ned at the scale of Grand Uni cation (GUT) and motivated by supergravity, like the Constrained MSSM (CMSSM) and the Non-Universal Higgs Mass (NUHM) model. In these models the favored parameter space shows sparticles in the range of a few TeV (see, e.g., [10]), somewhat decoupled from the EWSB scale, so that all precision observables are expected to yield values in agreement with the Standard Model (SM) within the present experimental sensitivity. As a bonus, one obtains a naturally embedded dark matter (DM) candidate, the lightest neutralino, which can easily satisfy the relic density constraint and yields signatures in reach of present and future direct and indirect DM searches. By and large precision observables and rare meson decays have been measured in recent years to be in good or even excellent agreement with the SM. However, there exist some long-standing anomalies that point to the existence of BSM physics close to the EWSB scale. The most outstanding and thoroughly studied among them is arguably the anomalous magnetic moment of the muon, (g 2) , which shows a deviation from the SM value at more than 3 [11, 12]. The anomaly will soon be either con rmed or falsi ed by the New Muon g-2 experiment at Fermilab [13, 14], which is projected to reach a sensitivity of 7 to possible BSM e ects. In SUSY, deviations from the SM value of (g 2) are mainly due to the contributions of smuon-neutralino and sneutrino-chargino loops, and require these states to be relatively light. Direct searches for these particles, at LEP rst and now at the LHC, constrain them above the few hundred GeV range, but even when recent direct LHC bounds are taken into account, the (g 2) anomaly can be easily explained in the framework of the MSSM [15{ 19]. It is much harder, however, to accommodate the discrepancy in GUT-constrained models. In particular, the bounds from direct squark and gluino searches at the LHC already exclude [20] the parameter space that would lead to the correct value of (g 2) in the CMSSM and the NUHM. The simplest, although (...truncated)


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Arghya Choudhury, Luc Darmé, Leszek Roszkowski, Enrico Maria Sessolo, Sebastian Trojanowski. Muon g − 2 and related phenomenology in constrained vector-like extensions of the MSSM, Journal of High Energy Physics, 2017, pp. 72, Volume 2017, Issue 5, DOI: 10.1007/JHEP05(2017)072