Wh plus missing-E_T signature from gaugino pair production at the LHC

In SUSY models with heavy squarks and gaugino mass unification, the gaugino pair production reaction pp-> \tw_1^\pm\tz_2 dominates gluino pair production for m_{\tg}\agt 1 TeV at LHC with \sqrt{s}=14 TeV (LHC14). For this mass range, the two-body decays \tw_1\to W\tz_1 and \tz_2\to h\tz_1 are expected to dominate the chargino and neutralino branching fractions. By searching for \ell b\bar{b}+MET events from \tw_1^\pm\tz_2 production, we show that LHC14 with 100 fb^{-1} of integrated luminosity becomes sensitive to chargino masses in the range m_{\tw_1}\sim 450-550 GeV corresponding to m_{\tg}\sim 1.5-2 TeV in models with gaugino mass unification. For 10^3 fb^{-1}, LHC14 is sensitive to the Wh channel for m_{\tw_1}\sim 300-800 GeV, corresponding to m_{\tg}\sim 1-2.8 TeV, which is comparable to the reach for gluino pair production followed by cascade decays. The Wh+MET search channel opens up a new complementary avenue for SUSY searches at LHC, and serves to point to SUSY as the origin of any new physics discovered via multijet and multilepton + MET channels.Comment: 5 pages with 4 .eps figure

Testing the gaugino AMSB model at the Tevatron via slepton pair production

Gaugino AMSB models-- wherein scalar and trilinear soft SUSY breaking terms are suppressed at the GUT scale while gaugino masses adopt the AMSB form-- yield a characteristic SUSY particle mass spectrum with light sleptons along with a nearly degenerate wino-like lightest neutralino and quasi-stable chargino. The left- sleptons and sneutrinos can be pair produced at sufficiently high rates to yield observable signals at the Fermilab Tevatron. We calculate the rate for isolated single and dilepton plus missing energy signals, along with the presence of one or two highly ionizing chargino tracks. We find that Tevatron experiments should be able to probe gravitino masses into the ~55 TeV range for inoAMSB models, which corresponds to a reach in gluino mass of over 1100 GeV.Comment: 14 pages including 6 .eps figure

Same-Sign Diboson Signature from Supersymmetry Models with Light Higgsinos at the LHC

In supersymmetric models with light Higgsinos (which are motivated by electroweak naturalness arguments), the direct production of Higgsino pairs may be difficult to search for at the LHC due to the low visible energy release from their decays. However, the wino pair production reaction [?] -\u3e ([?]) + ([?]) also occurs at substantial rates and leads to final states including equally oppositesign and same-sign diboson production. We propose a novel search channel for LHC14 based on the same-sign diboson plus missing ET final state which contains only modest jet activity. Assuming gaugino mass unification, and an integrated luminosity [?] 100 fb-1, this search channel provides a reach for supersymmetry well beyond that from usual gluino pair production

Radiatively-driven natural supersymmetry at the LHC

Radiatively-driven natural supersymmetry (RNS) potentially reconciles the Z and Higgs boson masses close to ∼ 100 GeV with gluinos and squarks lying beyond the TeV scale. Requiring no large cancellations at the electroweak scale in constructing MZ = 91.2 GeV while maintaining a light Higgs scalar with mh ≃ 125 GeV implies a sparticle mass spectrum including light higgsinos with mass ∼ 100−300 GeV, electroweak gauginos in the 300−1200 GeV range, gluinos at 1−4 TeV and top/bottom squarks in the 1-4 TeV range (probably beyond LHC reach), while first/second generation matter scalars can exist in the 5-30 TeV range (far beyond LHC reach). We investigate several characteristic signals for RNS at LHC14. Gluino pair production yields a reach up to [?] ∼ 1.7 TeV for 300 fb−1. Wino pair production — pp → [?] and [?] - leads to a unique same-sign diboson (SSdB) signature accompanied by modest jet activity from daughter higgsino decays; this signature provides the best reach up to [?] ∼ 2.1 TeV within this framework. Wino pair production also leads to final states with (WZ → 3[?]) + [?] as well as 4[?] + [?] which give confirmatory signals up to [?] ∼ 1.4 TeV. Directly produced light higgsinos yield a clean, soft trilepton signature (due to very low visible energy release) which can be visible, but only for a not-too-small a [?] mass gap. The clean SSdB signal - as well as the distinctive mass shape of the dilepton mass distribution from [?] decays if this is accessible - will mark the presence of light higgsinos which are necessary for natural SUSY. While an e+e- collider operating with [?] ~ 600 GeV should unequivocally reveal the predicted light higgsinos, the RNS model with m1/2 [?] 1 TeV may elude all LHC14 search strategies even while maintaining a high degree of electroweak naturalness

Mass spectrum of 1−−1^{--} heavy quarkonium

We calculate the masses and leptonic decay widths of the bottomonium $b\bar b$ and charmonium $c\bar c$ states in a constituent quark model where the Cornell-like potential and spin-dependent interaction are employed, with all model parameters predetermined by studying ground and first radial excited states of S- and P-wave heavy quarkonium mesons. By comparing the theoretical predictions for $J^{PC}=1^{--}$ quarkonium states with experimental data and considering possible mixtures of $nS$ and $(n-1)D$ states, we provide tentative assignments for all observed $J^{PC}=1^{--}$ heavy quarkonia. The work suggests that the $\Upsilon$(10860) and $\Upsilon$(11020) are $b\bar b$ $5S-4D$ mixture states, and the $\psi$(4360) and $\psi$(4415) are largely $4S$ and $3D$ $c\bar c$ states respectively. The $\psi$(4260) may not be accommodated with the conventional meson picture in the present work

Mixed axion/neutralino cold dark matter in supersymmetric models

We consider supersymmetric (SUSY) models wherein the strong CP problem is solved by the Peccei-Quinn (PQ) mechanism with a concommitant axion/axino supermultiplet. We examine R-parity conserving models where the neutralino is the lightest SUSY particle, so that a mixture of neutralinos and axions serve as cold dark matter. The mixed axion/neutralino CDM scenario can match the measured dark matter abundance for SUSY models which typically give too low a value of the usual thermal neutralino abundance, such as models with wino-like or higgsino-like dark matter. The usual thermal neutralino abundance can be greatly enhanced by the decay of thermally-produced axinos to neutralinos, followed by neutralino re-annihilation at temperatures much lower than freeze-out. In this case, the relic density is usually neutralino dominated, and goes as \sim (f_a/N)/m_{axino}^{3/2}. If axino decay occurs before neutralino freeze-out, then instead the neutralino abundance can be augmented by relic axions to match the measured abundance. Entropy production from late-time axino decays can diminish the axion abundance, but ultimately not the neutralino abundance. In mixed axion/neutralino CDM models, it may be possible to detect both a WIMP and an axion as dark matter relics. We also discuss possible modifications of our results due to production and decay of saxions. In the appendices, we present expressions for the Hubble expansion rate and the axion and neutralino relic densities in radiation, matter and decaying-particle dominated universes.Comment: 31 pages including 21 figure