Expectations for the muon g-2 in simplified models with dark matter

We investigate simplified models of new physics that can accommodate the measured value of the anomalous magnetic moment of the muon and the relic density of dark matter. We define a set of renormalizable, SU(2)$\times$U(1) invariant extensions of the Standard Model, each comprising an inert $Z_2$-odd scalar field and one or more vector-like pairs of colorless fermions that communicate to the muons through Yukawa-type interactions. The new sectors are classified according to their transformation properties under the Standard Model gauge group and all models are systematically confronted with a variety of experimental constraints: LEP mass bounds, direct LHC searches, electroweak precision observables, and direct searches for dark matter. We show that scenarios featuring only one type of new fermions become very predictive once the relic density and collider constraints are taken into account, as in this case $g-2$ is not enhanced by chirality flip. Conversely, for models where an additional source of chiral-symmetry violation is generated via fermion mixing, the constraints are much looser and new precision experiments with highly suppressed systematic uncertainties may be required to test the parameter space.Comment: 38 pages, 12 figures. Added constraints from CMS soft opposite-sign leptons and ATLAS h to gamma gamma. References added, typos fixed. Matches published versio

Gauge contribution to the 1/NF1/N_F expansion of the Yukawa coupling beta function

We provide a closed analytical form for the gauge contribution to the beta function of a generic Yukawa coupling in the limit of large $N_F$, where $N_F$ is the number of heavy vector-like fermions charged under an abelian or non-abelian gauge group. The resummed expression is finite and for the abelian case presents a pole at the same location as for the corresponding gauge beta function. When applied to new physics scenarios characterized by large Yukawa couplings, the contribution calculated here can cure their pathological UV behavior and make the couplings asymptotically free.Comment: 18 pages, 4 figures. Added clarification on our choice of gauge, which was previously stated incorrectly. Typos fixed. References adde

MSSM fits to the ATLAS 1 lepton excess

We use the framework of the p19MSSM to perform a fit to the mild excesses over the Standard Model background recently observed in three bins of the ATLAS 1-lepton + (b-)jets + MET search. We find a few types of spectra that can fit the emerging signal and at the same time are not excluded by other LHC searches. They can be grouped roughly in two categories. The first class is characterized by the presence of one stop or stop and sbottoms with mass in the ballpark of 700-800 GeV and a neutralino LSP of mass around 400 GeV, with or without the additional presence of an intermediate chargino. In the second type of scenarios the stop, lightest chargino, sbottom if present, and the neutralino are about or heavier than ~650 GeV and the signal originates from cascade decays of squarks of the 1st and 2nd generation, which should have a mass of 1.1-1.2 TeV. For the best-fit scenarios, we compare the global chi-squared with respect to several ATLAS and CMS searches with the corresponding chi-squared of the Standard Model expectation, showing that the putative signal is also favored globally with respect to the background only hypothesis. We point out that if the observed excess persists in the next round of data, it should be accompanied by associated significant excesses in all-hadronic final state searches.Comment: 21 pages, 2 figures. Added recast of CMS 1-lepton search. Added global analysis of chi-squared contributions from all implemented searches. Added references. Matches published versio

The discreet charm of higgsino dark matter - a pocket review

We give a brief review of the current constraints and prospects for detection of higgsino dark matter in low-scale supersymmetry. In the first part we argue, after performing a survey of all potential dark matter particles in the MSSM, that the (nearly) pure higgsino is the only candidate emerging virtually unscathed from the wealth of observational data of recent years. In doing so by virtue of its gauge quantum numbers and electroweak symmetry breaking only, it maintains at the same time a relatively high degree of model-independence. In the second part we properly review the prospects for detection of a higgsino-like neutralino in direct underground dark matter searches, collider searches, and indirect astrophysical signals. We provide estimates for the typical scale of the superpartners and fine tuning in the context of traditional scenarios where the breaking of supersymmetry is mediated at about the scale of Grand Unification and where strong expectations for a timely detection of higgsinos in underground detectors are closely related to the measured 125 GeV mass of the Higgs boson at the LHC.Comment: 30 pages, 7 figures. Invited review for Advances in High Energy Physics. v3: References added, matches published versio

Flavored gauge mediation in the Peccei-Quinn NMSSM

We investigate a particular version of the Peccei-Quinn (PQ) NMSSM characterized by an economical and rigidly hierarchical flavor structure and based on flavored gauge mediation and on some considerations inspired by string theory GUTs. In this way we can express the Lagrangian of the PQ NMSSM through very few parameters. The obtained model is studied numerically and confronted with the most relevant phenomenological constraints. We show that typical spectra are for the most part too heavy to be significantly probed at the LHC, but regions of the parameter space exist yielding signatures that might possibly be observed during Run II. We also calculate the fine tuning of the model. We show that, in spite of the appearance of large scales in the superpotential and soft terms, it does not exceed the tuning present in the MSSM for equivalent spectra, which is of the order of 10^4.Comment: 23 pages, 3 figures. Some clarifications added to the text, JHEP published versio

Two ultimate tests of constrained supersymmetry

We examine the prospects of using two alternative and complementary ways to explore the regions that are favored by global constraints in two simple unified supersymmetric models: the CMSSM and the NUHM. First, we consider BR(Bs->\mu\mu), which has recently been for the first time measured by LHCb. In the CMSSM we show that ultimate, but realistic, improvement in the determination of the observable to about 5-10% around the Standard Model value would strongly disfavor the A-funnel region, while not affecting much the other favored regions. Second, we show that all the favored regions of the CMSSM will be, for the most part, sensitive to direct dark matter searches in future one-tonne detectors. A signal at low WIMP mass (<=450 GeV) and low spin-independent cross section would then strongly favor the stau coannihilation region while a signal at higher WIMP mass (~800 GeV to ~1.2 TeV) would clearly point to the region where the neutralino is higgsino-like with mass ~1 TeV. A nearly complete experimental testing of the CMSSM over multi-TeV ranges of superpartner masses, far beyond the reach of direct SUSY searches at the LHC, can therefore be achievable. In the NUHM, in contrast, similar favored regions exist but a sample study reveals that even a precise determination of BR(Bs->\mu\mu) would have a much less constraining power on the model, including the A-funnel region. On the other hand, this could allow one to, by detecting in one-tonne detectors a signal for 500 GeV<m_{\chi}<800 GeV, strongly disfavor the CMSSM.Comment: 32 pages, 11 figures. Discussion of the properties of the higgsino region extended. One figure added. Version published in JHE

What next for the CMSSM and the NUHM: Improved prospects for superpartner and dark matter detection

We present an updated analysis of the CMSSM and the NUHM using the latest experimental data and numerical tools. We map out favored regions of Bayesian posterior probability in light of data from the LHC, flavor observables, the relic density and dark matter searches. We present some updated features with respect to our previous analyses: we include the effects of corrections to the light Higgs mass beyond the 2-loop order using FeynHiggs v2.10.0; we include in the likelihood the latest limits from direct searches for squarks and gluinos at ATLAS with ~20/fb; the latest constraints on the spin-independent scattering cross section of the neutralino from LUX are applied taking into account uncertainties in the nuclear form factors. We find that in the CMSSM the posterior distribution now tends to favor smaller values of Msusy than in the previous analyses. As a consequence, the statistical weight of the A-resonance region increases to about 30% of the total probability, with interesting new prospects for the 14 TeV run at the LHC. The most favored region, on the other hand, still features multi-TeV squarks and gluinos, and ~1TeV higgsino dark matter whose detection prospects by current and one-tonne detectors look very promising. The same region is predominant in the NUHM, although the A-resonance region is also present there as well as a new solution, of neutralino-stau coannihilation through the channel stau stau -> hh at very large \mu. We derive the expected sensitivity of the future CTA experiment to ~1 TeV higgsino dark matter for both models and show that the prospects for probing both models are realistically good. We comment on the complementarity of this search to planned direct detection one-tonne experiments.Comment: 37 pages, 15 figures. Appendix added showing the future constraints on the CMSSM, including an updated calculation of the sensitivity of CTA presented in arXiv:1411.521