Flavor and Collider Signatures of Asymmetric Dark Matter

We consider flavor constraints on, and collider signatures of, Asymmetric Dark Matter (ADM) via higher dimension operators. In the supersymmetric models we consider, R-parity violating (RPV) operators carrying B-L interact with n dark matter (DM) particles X through an interaction of the form W = X^n O_{B-L}, where O_{B-L} = q l d^c, u^c d^c d^c, l l e^c. This interaction ensures that the lightest ordinary supersymmetric particle (LOSP) is unstable to decay into the X sector, leading to a higher multiplicity of final state particles and reduced missing energy at a collider. Flavor-violating processes place constraints on the scale of the higher dimension operator, impacting whether the LOSP decays promptly. While the strongest limitations on RPV from n-\bar{n} oscillations and proton decay do not apply to ADM, we analyze the constraints from meson mixing, mu-e conversion, mu -> 3 e and b -> s l^+ l^-. We show that these flavor constraints, even in the absence of flavor symmetries, allow parameter space for prompt decay to the X sector, with additional jets and leptons in exotic flavor combinations. We study the constraints from existing 8 TeV LHC SUSY searches with (i) 2-6 jets plus missing energy, and (ii) 1-2 leptons, 3-6 jets plus missing energy, comparing the constraints on ADM-extended supersymmetry with the usual supersymmetric simplified models.Comment: 63 pages, 26 figures, 10 tables, revtex

Kinematic Cusps: Determining the Missing Particle Mass at Colliders

In many extensions of the SM, neutral massive stable particles (dark matter candidates) are produced at colliders in pairs due to an exact symmetry called a "parity". These particles escape detection, rendering their mass measurement difficult. In the pair production of such particles via a specific ("antler") decay topology, kinematic cusp structures are present in the invariant mass and angular distributions of the observable particles. Together with the end-points, such cusps can be used to measure the missing particle mass and the intermediate particle mass in the decay chain. Our simulation of a benchmark scenario in a Z' supersymmetric model shows that the cusp feature survives under the consideration of detector simulation and the standard model backgrounds. This technique for determining missing particle masses should be invaluable in the search for new physics at the LHC and future lepton colliders.Comment: final version in Phys. Lett.

On Models of New Physics for the Tevatron Top A_FB

CDF has observed a top forward-backward asymmetry discrepant with the Standard Model prediction at 3.4 \sigma. We analyze models that could generate the asymmetry, including flavor-violating W's, horizontal Z'_Hs, triplet and sextet diquarks, and axigluons. We consider the detailed predictions of these models for the invariant mass and rapidity distributions of the asymmetry at the parton level, comparing against the unfolded parton-level CDF results. While all models can reproduce the asymmetry with the appropriate choice of mass and couplings, it appears at first examination that the extracted parton-level invariant mass distribution for all models are in conflict with Tevatron observations. We show on closer examination, however, that t tbar events in Z'_H and W' models have considerably lower selection efficiencies in high invariant mass bins as compared to the Standard Model, so that W', Z'_H, and axigluon models can generate the observed asymmetry while being consistent with the total cross-section and invariant mass spectrum. Triplet and sextet models have greater difficulty producing the observed asymmetry while remaining consistent with the total cross-section and invariant mass distribution. To more directly match the models and the CDF results, we proceed to decay and reconstruct the tops, comparing our results against the "raw" CDF asymmetry and invariant mass distributions. We find that the models that successfully generate the corrected CDF asymmetry at the parton level reproduce very well the more finely binned uncorrected asymmetry. Finally, we discuss the early LHC reach for discovery of these models, based on our previous analysis [arXiv:1102.0018].Comment: 29 pages, 14 figures, 2 table

Closing the Wedge: Search Strategies for Extended Higgs Sectors with Heavy Flavor Final States

We consider search strategies for an extended Higgs sector at the high-luminosity LHC14 utilizing multi-top final states. In the framework of a Two Higgs Doublet Model, the purely top final states ($t\bar t, \, 4t$) are important channels for heavy Higgs bosons with masses in the wedge above $2\,m_t$ and at low values of $\tan\beta$, while a $2 b 2t$ final state is most relevant at moderate values of $\tan \beta$. We find, in the $t\bar t H$ channel, with $H \rightarrow t \bar t$, that both single and 3 lepton final states can provide statistically significant constraints at low values of $\tan \beta$ for $m_A$ as high as $\sim 750$ GeV. When systematics on the $t \bar t$ background are taken into account, however, the 3 lepton final state is more powerful, though the precise constraint depends fairly sensitively on lepton fake rates. We also find that neither $2b2t$ nor $t \bar t$ final states provide constraints on additional heavy Higgs bosons with couplings to tops smaller than the top Yukawa due to expected systematic uncertainties in the $t \bar t$ background.Comment: Added a Fig. and updated references. Matches journal version. 31 pages, 11 figure

Moduli Stabilization and Supersymmetry Breaking in Deflected Mirage Mediation

We present a model of supersymmetry breaking in which the contributions from gravity/modulus, anomaly, and gauge mediation are all comparable. We term this scenario "deflected mirage mediation," which is a generalization of the KKLT-motivated mirage mediation scenario to include gauge mediated contributions. These contributions deflect the gaugino mass unification scale and alter the pattern of soft parameters at low energies. In some cases, this results in a gluino LSP and light stops; in other regions of parameter space, the LSP can be a well-tempered neutralino. We demonstrate explicitly that competitive gauge-mediated terms can naturally appear within phenomenological models based on the KKLT setup by addressing the stabilization of the gauge singlet field which is responsible for the masses of the messenger fields. For viable stabilization mechanisms, the relation between the gauge and anomaly contributions is identical in most cases to that of deflected anomaly mediation, despite the presence of the Kahler modulus. Turning to TeV scale phenomenology, we analyze the renormalization group evolution of the supersymmetry breaking terms and the resulting low energy mass spectra. The approach sets the stage for studies of such mixed scenarios of supersymmetry breaking at the LHC.Comment: 33 pages, 8 figures. Published version in Journal of High Energy Physic