Search

This paper investigates the decays from heavy higgsino-like weak-doublets into Z, h bosons and missing particles. When pair-produced at the LHC, the subsequent Z, h to 2l, 2b decays in the doublet decay cascade can yield 4l, 2l 2b, and 4b + MET + jets final states. Mutual observation of any two of these channels would provide information on the the associated doublets' decay branching fractions into a Z or h, thereby probing the Goldstone equivalence relation, shedding additional light on the Higgs sector of beyond the Standard Model theories, and facilitating the discrimination of various contending models, in turn. We compare the Z/h decay ratio expected in the Minimal Supersymmetric model, the Next-to Minimal Supersymmetric model and a minimal singlet-doublet dark matter model. Additionally, we conduct a full Monte Carlo analysis of the prospects for detecting the targeted final states during 14 TeV running of the LHC in the context of a representative NMSSM benchmark model., Comment: As accepted to PRD; 15 pages, 12 figures, 5 tables

We study dark matter (DM) which is cosmologically long-lived because of standard model (SM) symmetries. In these models an approximate stabilizing symmetry emerges accidentally, in analogy with baryon and lepton number in the renormalizable SM. Adopting an effective theory approach, we classify DM models according to representations of $SU(3)_C\times SU(2)_L\times U(1)_Y \times U(1)_B\times U(1)_L$, allowing for all operators permitted by symmetry, with weak scale DM and a cutoff at or below the Planck scale. We identify representations containing a neutral long-lived state, thus excluding dimension four and five operators that mediate dangerously prompt DM decay into SM particles. The DM relic abundance is obtained via thermal freeze-out or, since effectively stable DM often carries baryon or lepton number, asymmetry sharing through the very operators that induce eventual DM decay. We also incorporate baryon and lepton number violation with a spurion that parameterizes hard breaking by arbitrary units. However, since proton stability precludes certain spurions, a residual symmetry persists, maintaining the cosmological stability of certain DM representations. Finally, we survey the phenomenology of effectively stable DM as manifested in probes of direct detection, indirect detection, and proton decay., Comment: 7 pages, 1 figure, 4 tables

We explore models for the GeV Galactic Center Excess (GCE) observed by the Fermi Telescope, focusing on $\chi \chi \rightarrow f \bar f$ annihilation processes in the $Z_3$ NMSSM. We begin by examining the requirements for a simplified model (parametrized by the couplings and masses of dark matter (DM) and mediator particles) to reproduce the GCE via $\chi \chi \rightarrow f \bar f$, while simultaneously thermally producing the observed relic abundance. We apply the results of our simplified model to the $Z_3$ NMSSM for Singlino/Higgsino(S/H) or Bino/Higgsino(B/H) DM. In the case of S/H DM, we find that the DM must be be very close to a pseudoscalar resonance to be viable, and large $\tan\beta$ and positive values of $\mu$ are preferred for evading direct detection constraints while simultaneously obtaining the observed Higgs mass. In the case of B/H DM, by contrast, the situation is much less tuned: annihilation generally occurs off-resonance, and for large $\tan\beta$ direct detection constraints are easily satisfied by choosing $\mu$ sufficiently large and negative. The B/H model generally has a light, largely MSSM-like pseudoscalar with no accompanying charged Higgs, which could be searched for at the LHC., Comment: 43 pages, 6 figures, references updates to correspond to published version

We explore simplified models of mixed dark matter (DM), defined here to be a stable relic composed of a singlet and an electroweak charged state. Our setup describes a broad spectrum of thermal DM candidates that can naturally accommodate the observed DM abundance but are subject to substantial constraints from current and upcoming direct detection experiments. We identify "blind spots" at which the DM-Higgs coupling is identically zero, thus nullifying direct detection constraints on spin independent scattering. Furthermore, we characterize the fine-tuning in mixing angles, i.e. well-tempering, required for thermal freeze-out to accommodate the observed abundance. Present and projected limits from LUX and XENON1T force many thermal relic models into blind spot tuning, well-tempering, or both. This simplified model framework generalizes bino-Higgsino DM in the MSSM, singlino-Higgsino DM in the NMSSM, and scalar DM candidates that appear in models of extended Higgs sectors., Comment: 42 pages, 19 figures

In this Report we discuss the four complementary searches for the identity of dark matter: direct detection experiments that look for dark matter interacting in the lab, indirect detection experiments that connect lab signals to dark matter in our own and other galaxies, collider experiments that elucidate the particle properties of dark matter, and astrophysical probes sensitive to non-gravitational interactions of dark matter. The complementarity among the different dark matter searches is discussed qualitatively and illustrated quantitatively in several theoretical scenarios. Our primary conclusion is that the diversity of possible dark matter candidates requires a balanced program based on all four of those approaches., Comment: Snowmass 2013 CF4 Working Group Report

Isospin-violating dark matter (IVDM) generalizes the standard spin-independent scattering parameter space by introducing one additional parameter, the neutron-to-proton coupling ratio f_n/f_p. In IVDM the implications of direct detection experiments can be altered significantly. We review the motivations for considering IVDM and present benchmark models that illustrate some of the qualitatively different possibilities. IVDM strongly motivates the use of a variety of target nuclei in direct detection experiments., Comment: LaTeX, 5 pages, 4 figures. v2: minor figure revisions

We briefly review the motivations and features of focus point supersymmetry and in particular the focus point region of the CMSSM. Applying the constraint that the neutralino is a thermal relic, we examine current and projected collider and dark matter constraints on the focus point region. We demonstrate that the focus point region is currently constrained by multiple dark matter experiments, and future sensitivy on multiple fronts will probe large portions of the parameter space., Comment: 4 pages, 1 figure

We consider models of xenophobic dark matter, in which isospin-violating dark matter-nucleon interactions significantly degrade the response of xenon direct detection experiments. For models of near-maximal xenophobia, with neutron-to-proton coupling ratio $f_n / f_p \approx -0.64$, and dark matter mass near 8 GeV, the regions of interest for CoGeNT and CDMS-Si and the region of interest identified by Collar and Fields in CDMS-Ge data can be brought into agreement. This model may be tested in future direct, indirect, and collider searches. Interestingly, because the natural isotope abundance of xenon implies that xenophobia has its limits, we find that this xenophobic model may be probed in the near future by xenon experiments. Near-future data from the LHC and Fermi-LAT may also provide interesting alternative probes of xenophobic dark matter., Comment: 15 pages, 4 figures

In supersymmetric models with minimal particle content and without left-right squark mixing, the conventional wisdom is that the 125.6 GeV Higgs boson mass implies top squark masses of O(10) TeV, far beyond the reach of colliders. This conclusion is subject to significant theoretical uncertainties, however, and we provide evidence that it may be far too pessimistic. We evaluate the Higgs boson mass, including the dominant three-loop terms at O(\alpha_t \alpha_s^2), in currently viable models. For multi-TeV stops, the three-loop corrections can increase the Higgs boson mass by as much as 3 GeV and lower the required stop mass to 3 to 4 TeV, greatly improving prospects for supersymmetry discovery at the upcoming run of the LHC and its high-luminosity upgrade., Comment: 4 pages; v2: enhanced discussion of comparison with other results, added reference; v3: published version

We determine the prospects for direct and indirect detection of thermal relic neutralinos in supersymmetric theories with multi-TeV squarks and sleptons. We consider the concrete example of the focus point region of minimal supergravity, but our results are generically valid for all models with decoupled scalars and mixed Bino-Higgsino or Higgsino-like dark matter. We determine the parameter space consistent with a 125 GeV Higgs boson including 3-loop corrections in the calculation of the Higgs mass. These corrections increase m_h by 1-3 GeV, lowering the preferred scalar mass scale and decreasing the fine-tuning measure in these scenarios. We then systematically examine prospects for dark matter direct and indirect detection. Direct detection constraints do not exclude these models, especially for \mu < 0. At the same time, the scenario generically predicts spin-independent signals just beyond current bounds. We also consider indirect detection with neutrinos, gamma rays, anti-protons, and anti-deuterons. Current IceCube neutrino constraints are competitive with direct detection, implying bright prospects for complementary searches with both direct and indirect detection., Comment: 22 pages, 11 figures; v2: added references, published version

We show that a 125 GeV Higgs boson and percent-level fine-tuning are simultaneously attainable in the MSSM, with no additional fields and supersymmetry breaking generated at the GUT scale. The Higgs mass is raised by large radiative contributions from top squarks with significant left-right mixing, and naturalness is preserved by the focus point mechanism with large $A$-terms, which suppresses large log-enhanced sensitivities to variations in the fundamental parameters. The focus point mechanism is independent of almost all supersymmetry-breaking parameters, but is predictive in the top sector, requiring the GUT-scale relation $m_{H_u}^2 : m_{\bar{U}_3}^2 : m_{Q_3}^2 : A_t^2 = 1 : 1+x - 3y : 1-x : 9y$, where $x$ and $y$ are constants. We derive this condition analytically and then investigate three representative models through detailed numerical analysis. The models generically predict heavy superpartners, but dark matter searches in the case of non-unified gaugino masses are promising, as are searches for top squarks and gluinos with top and bottom-rich cascade decays at the LHC. This framework may be viewed as a simple update to mSUGRA/CMSSM to accommodate both naturalness and current Higgs boson constraints, and provides an ideal framework for presenting new results from LHC searches., Comment: 18 pages, 8 figures

We derive bounds on the dark matter annihilation cross-section for low-mass (5-20 GeV) dark matter annihilating primarily to up or down quarks, using the Fermi-LAT bound on gamma-rays from Milky Way satellites. For models in which dark matter-Standard Model interactions are mediated by particular contact operators, we show that these bounds can be directly translated into bounds on the dark matter-proton scattering cross-section. For isospin-violating dark matter, these constraints are tight enough to begin to constrain the parameter-space consistent with experimental signals of low-mass dark matter. We discuss possible models that can evade these bounds., Comment: 6 pages, 2 figures, LaTeX, some clarifications and minor errors corrected, citations added

Recent results from Higgs boson and supersymmetry searches at the Large Hadron Collider provide strong new motivations for supersymmetric theories with heavy superpartners. We reconsider focus point supersymmetry (FP SUSY), in which all squarks and sleptons may have multi-TeV masses without introducing fine-tuning in the weak scale with respect to variations in the fundamental SUSY-breaking parameters. We examine both FP SUSY and its familiar special case, the FP region of mSUGRA/CMSSM, and show that they are beautifully consistent with all particle, astroparticle, and cosmological data, including Higgs boson mass limits, null results from SUSY searches, electric dipole moments, b -> s gamma, B_s -> mu^+ mu^-, the thermal relic density of neutralinos, and dark matter searches. The observed deviation of the muon's anomalous magnetic moment from its standard model value may also be explained in FP SUSY, although not in the FP region of mSUGRA/CMSSM. In light of recent data, we advocate refined searches for FP SUSY and related scenarios with heavy squarks and sleptons, and we present a simplified parameter space to aid such analyses., Comment: v3: 20 pages, 20 figures, minor numerical error in relic density calculation corrected, fixed contours in figure 5

Searches for dark matter scattering off nuclei are typically compared assuming that the dark matter's spin-independent couplings are identical for protons and neutrons. This assumption is neither innocuous nor well motivated. We consider isospin-violating dark matter (IVDM) with one extra parameter, the ratio of neutron to proton couplings, and include the isotope distribution for each detector. For a single choice of the coupling ratio, the DAMA and CoGeNT signals are consistent with each other and with current XENON constraints, and they unambiguously predict near future signals at XENON and CRESST. We provide a quark-level realization of IVDM as WIMPless dark matter that is consistent with all collider and low-energy bounds., Comment: 5 pages; v2: added references and fixed figures for Mac users; v3: published version; v4: fixed erroneous Ar values in table I

In this paper we reconsider the derivation of anomaly mediated supersymmetry breaking. We work in a general formalism where the F-term of the conformal compensator superfield is arbitrary. This allows for a continuous interpolation between the original derivation and a more recent Dine-Seiberg derivation of anomaly mediation. We show that the physical soft parameters are independent of the compensator F-term and results of two formalisms agree. Finally, we discuss the role of supersymmetric and non-supersymmetric thresholds in the effective low energy Lagrangian as well as the effects of explicit small mass parameters (such as mu-term) on the superpartner spectrum., Comment: 19 pages; v3, published version

The direct detection of dark matter through its elastic scattering off nucleons is among the most promising methods for establishing the particle identity of dark matter. The current bound on the spin-independent scattering cross section is sigma^SI < 10 zb for dark matter masses m_chi ~ 100 GeV, with improved sensitivities expected soon. We examine the implications of this progress for neutralino dark matter. We work in a supersymmetric framework well-suited to dark matter studies that is simple and transparent, with models defined in terms of four weak-scale parameters. We first show that robust constraints on electric dipole moments motivate large sfermion masses mtilde > 1 TeV, effectively decoupling squarks and sleptons from neutralino dark matter phenomenology. In this case, we find characteristic cross sections in the narrow range 1 zb < sigma^SI < 40 zb for m_chi > 70 GeV. As sfermion masses are lowered to near their experimental limit mtilde ~ 400 GeV, the upper and lower limits of this range are extended, but only by factors of around two, and the lower limit is not significantly altered by relaxing many particle physics assumptions, varying the strange quark content of the nucleon, including the effects of galactic small-scale structure, or assuming other components of dark matter. Experiments are therefore rapidly entering the heart of dark matter-favored supersymmetry parameter space. If no signal is seen, supersymmetric models must contain some level of fine-tuning, and we identify and analyze several possibilities. Barring large cancellations, however, in a large and generic class of models, if thermal relic neutralinos are a significant component of dark matter, experiments will discover them as they probe down to the zeptobarn scale., Comment: 35 pages, 11 figures; v2: references added, figures extended to 2 TeV neutralino masses, XENON100 results included, published version

Flavor physics may help us understand theories beyond the standard model. In the context of supersymmetry, if we can measure the masses and mixings of sleptons and squarks, we may learn something about supersymmetry and supersymmetry breaking. Here we consider a hybrid gauge-gravity supersymmetric model in which the observed masses and mixings of the standard model leptons are explained by a U(1) x U(1) flavor symmetry. In the supersymmetric sector, the charged sleptons have reasonably large flavor mixings, and the lightest is metastable. As a result, supersymmetric events are characterized not by missing energy, but by heavy metastable charged particles. Many supersymmetric events are therefore fully reconstructible, and we can reconstruct most of the charged sleptons by working up the long supersymmetric decay chains. We obtain promising results for both masses and mixings, and conclude that, given a favorable model, precise measurements at the LHC may help shed light not only on new physics, but also on the standard model flavor parameters., Comment: 24 pages; v2: fixed a typo in our computer program that led to some miscalculated branching ratios, various clarifications and minor improvements, conclusions unchanged, published version

We determine the widths of three-body decays of sleptons, $\tilde{l}^- \to \tilde{l}^{\pm} l^- l^{\mp}, \tilde{l}^- \nu \bar{\nu}, \tilde{l}^- q \bar{q}$, in the presence of arbitrary slepton flavor violation and left-right mixing. These decays are important in scenarios in which the lightest supersymmetric particle is the gravitino, a generic possibility in models with gauge- and gravity-mediated supersymmetry breaking. Three-body decays have been discussed previously assuming flavor conservation and left-right mixing in only the stau sector. Flavor violation and general left-right mixing open up many new decay channels, which provide new avenues for precision mass measurements and may play an essential role in solving the standard model flavor problem. We present results for toy models with two-generation mixing, and discuss the implementation of these results in SPICE, a program that simplifies collider event simulations of flavor-violating supersymmetric models., Comment: 25 pages, 5 figures; v2: published version

We describe SPICE: Simulation Package for Including Flavor in Collider Events. SPICE takes as input two ingredients: a standard flavor-conserving supersymmetric spectrum and a set of flavor-violating slepton mass parameters, both of which are specified at some high "mediation" scale. SPICE then combines these two ingredients to form a flavor-violating model, determines the resulting low-energy spectrum and branching ratios, and outputs HERWIG and SUSY LesHouches files, which may be used to generate collider events. The flavor-conserving model may be any of the standard supersymmetric models, including minimal supergravity, minimal gauge-mediated supersymmetry breaking, and anomaly-mediated supersymmetry breaking supplemented by a universal scalar mass. The flavor-violating contributions may be specified in a number of ways, from specifying charges of fields under horizontal symmetries to completely specifying all flavor-violating parameters. SPICE is fully documented and publicly available, and is intended to be a user-friendly aid in the study of flavor at the Large Hadron Collider and other future colliders., Comment: 31 pages, 3 figures, SPICE can be downloaded from http://hep.ps.uci.edu/~spice; v2: published version