119279570
Dark matter and Higgs bosons in the MSSM
A bstractWe investigate dark matter (DM) in the context of the minimal supersymmetric extension of the standard model (MSSM). We scan through the MSSM parameter space and search for solutions that (a) are consistent with the Higgs discovery and other collider searches; (b) satisfy the flavor constraints from B physics; (c) give a DM candidate with the correct thermal relic density; and (d) are allowed by the DM direct detection experiments. For the surviving models with our parameter scan, we find the following features: (1) The DM candidate is largely a Bino-like neutralino with non-zero but less than 20% Wino and Higgsino fractions; (2) The relic density requirement clearly pins down the solutions from the Z and Higgs resonances (Z, h, H, A funnels) and co-annihilations; (3) Future direct search experiments will likely fully cover the Z, h funnel regions, and H, A funnel regions as well except for the “blind spots”; (4) Future indirect search experiments will be more sensitive to the CP-odd Higgs exchange due to its s-wave nature; (5) The branching fraction for the SM-like Higgs decay to DM can be as high as 10%, while those from heavier Higgs decays to neutralinos and charginos can be as high as 20%. We show that collider searches provide valuable information complementary to what may be obtained from direct detections and astroparticle observations. In particular, the Z- and h-funnels with a predicted low LSP mass should be accessible at future colliders. Overall, the Higgs bosons may play an essential role as the portal to the dark sector.
119237150
Exotic decays of the 125 GeV Higgs boson
We perform an extensive survey of non-standard Higgs decays that are consistent with the 125 GeV Higgs-like resonance. Our aim is to motivate a large set of new experimental analyses on the existing and forthcoming data from the Large Hadron Collider (LHC). The explicit search for exotic Higgs decays presents a largely untapped discovery opportunity for the LHC collaborations, as such decays may be easily missed by other searches. We emphasize that the Higgs is uniquely sensitive to the potential existence of new weakly coupled particles and provide a unified discussion of a large class of both simplified and complete models that give rise to characteristic patterns of exotic Higgs decays. We assess the status of exotic Higgs decays after LHC Run 1. In many cases we are able to set new nontrivial constraints by reinterpreting existing experimental analyses. We point out that improvements are possible with dedicated analyses and perform some preliminary collider studies. We prioritize the analyses according to their theoretical motivation and their experimental feasibility. This document is accompanied by a website that will be continuously updated with further information: this http URL
119240667
Radiative return for heavy Higgs boson at a muon collider
Higgs boson properties could be studied with a high accuracy at a muon collider via the $s$-channel resonant production. We consider the situation where the center-of-mass energy of the muon collider is off the resonance above the Higgs mass. We discuss the discovery potential for a generic heavy Higgs boson and compare different production mechanisms, including the ``radiative return,'' $Z$-boson associated production and heavy Higgs pair production. These production mechanisms do not sensitively rely on a priori knowledge of the heavy Higgs boson mass. We include various types of two-Higgs-doublet models for the comparison. We conclude that the radiative return process could provide an important option for both the heavy Higgs discovery and direct measurement of invisible decays at a high energy muon collider.
117360716
Diagnosis of a New Neutral Gauge Boson at the LHC and ILC for Snowmass 2013
A U(1)' or Z' is generic in many scenarios of physics beyond the Standard Model, such as string theory compactifications, GUTs, extra-dimensions, compositeness, dynamical electroweak symmetry breaking, dark-sector models, etc. We study the potential of probing a TeV-scale Z' with electroweak couplings in future experiments. In particular, we focus on two scenarios: (1) If a Z' is discovered at the LHC, what is the potential of measuring its mass and width and to distinguish between benchmark models utilizing various observables, especially asymmetries, at a high luminosity LHC and the ILC. (2) If the Z' is not accessible as a clear resonance signal, what is the exclusion reach at the ILC.
55815228
Muon Collider Higgs Factory for Snowmass 2013
Author(s): Alexahin, Y; Ankenbrandt, CM; Cline, DB; Conway, A; Cummings, MA; Benedetto, VD; Eichten, E; Gatto, C; Grinstein, B; Gunion, J; Han, T; Hanson, G; Hill, CT; Ignatov, F; Johnson, RP; Lebedev, V; Lipton, R; Liu, Z; Markiewicz, T; Mazzacane, A; Mokhov, N; Nagaitsev, S; Neuffer, D; Palmer, M; Purohit, MV; Raja, R; Striganov, S; Summers, D; Terentiev, N; Wenzel, H | Abstract: We propose the construction of, and describe in detail, a compact Muon Collider s-channel Higgs Factory.
54185957
Colored resonant signals at the LHC: largest rate and simplest topology
We study the colored resonance production at the LHC in a most general approach. We classify the possible colored resonances based on group theory decomposition, and construct their effective interactions with light partons. The production cross section from annihilation of valence quarks or gluons may be on the order of 400–1000 pb at LHC energies for a mass of 1 TeV with nominal couplings, leading to the largest production rates for new physics at the TeV scale, and simplest event topology with dijet final states. We apply the new dijet data from the LHC experiments to put bounds on various possible colored resonant states. The current bounds range from 0.9 to 2.7 TeV. The formulation is readily applicable for future searches including other decay modes.
118650719
New Constraints on Dark Matter from CMS and ATLAS Data
Constraints on dark matter from the first CMS and ATLAS SUSY searches are investigated. It is shown that within the minimal supergravity model, the early search for supersymmetry at the LHC has depleted a large portion of the signature space in dark matter direct detection experiments. In particular, the prospects for detecting signals of dark matter in the XENON and CDMS experiments are significantly affected in the low neutralino mass region. Here the relic density of dark matter typically arises from slepton coannihilations in the early universe. In contrast, it is found that the CMS and ATLAS analyses leave untouched the Higgs pole and the Hyperbolic Branch/Focus Point regions, which are now being probed by the most recent XENON results. Analysis is also done for supergravity models with non-universal soft breaking where one finds that a part of the dark matter signature space depleted by the CMS and ATLAS cuts in the minimal SUGRA case is repopulated. Thus, observation of dark matter in the LHC depleted region of minimal supergravity may indicate non-universalities in soft breaking.
53509420
Explaining PAMELA and WMAP data through coannihilations in extended SUGRA with collider implications
The PAMELA positron excess is analyzed within the framework of nonuniversal supergravity (SUGRA) models with an extended $U(1{)}^{n}$ gauge symmetry in the hidden sector leading to neutralino dark matter with either a mixed Higgsino-wino lightest $R$-parity odd supersymmetric particle (LSP) or an essentially pure wino-dominated LSP. The Higgsino-wino LSP can produce the observed PAMELA positron excess and satisfy relic density constraints in the extended class of models due to a near degeneracy of the mass spectrum of the extended neutralino sector with the LSP mass. The simultaneous satisfaction of the WMAP relic density data and the PAMELA data is accomplished through a coannihilation mechanism (${B}_{\mathrm{Co}}\ensuremath{-}\mathrm{\text{mechanism}}$), and leads to predictions of a neutralino and a chargino in the mass range (180--200) GeV as well as low-lying sparticles accessible at colliders. We show that the models are consistent with the antiproton constraints from PAMELA as well as the photon flux data from EGRET and FERMI-LAT. Predictions for the scalar neutralino-proton cross section relevant for the direct detection of dark matter are also discussed and signatures at the LHC for these PAMELA inspired models are analyzed. It is shown that the mixed Higgsino-wino LSP model will be discoverable with as little as $1\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$ of data and is thus a prime candidate for discovery in the low luminosity runs at the LHC.
120107147
Partial wave analysis of psi-prime ---> pi+ pi- pi0 at BESII
18308235
Search for new particles in hadronic events with isolated photons
Abstract A search for the neutral Higgs boson in the processes e + e − → Z → H 0 γ → q q γ and e + e − → Z → Z ∗ H 0 → q q γγ has been performed using 2.8 million hadronic Z decays collected with the L3 detector at LEP from 1991 through 1994. No evidence for these processes has been observed. Upper limits at 95% confidence level for the corresponding cross sections have been set and the results have been compared with theoretical predictions beyond the Standard Model.
116940362
Measurement of the Probability of Gluon Splitting into Charmed Quarks in Hadronic Z Decays
We have measured the probability, $\overline{n}_{\rm{g} \rightarrow c\overline{c}}$, of a gluon splitting into a charm-quark pair using 1.7 million hadronic Z decays collected by the L3 detector. Two independent methods have been applied to events with a three-jet topology. One method relies on tagging charmed hadrons by identifying a lepton in the lowest energy jet. The other method uses a neural network based on global event shape parameters. Combining both methods, we measure $\overline{n}_{\rm{g} \rightarrow c\overline{c} } = [2.45 \pm 0.29 \pm 0.53]\$.