24,763 research outputs found

    Heavy QQ(bar) "Fireball" Annihilation to Multiple Vector Bosons

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    Drawing analogy of replacing the nucleon by heavy chiral quark QQ, the pion by Goldstone boson GG, and πNN\pi NN coupling by GQQGQQ coupling, we construct a statistical model for QQˉnGQ\bar Q \to nG annihilation, i.e. into nn longitudinal weak bosons. This analogy is becoming prescient since the LHC direct bound mQ>611m_Q > 611 GeV implies strong Yukawa coupling. Taking mQ(1,2)m_Q \in (1, 2) TeV, the mean number ranges from 6 to over 10, with negligible two or three boson production. With individual tt' or bb' decays suppressed either by phase space or quark mixing, and given the strong Yukawa coupling, QQˉnVLQ\bar Q\to nV_L is the likely outcome for very heavy QQˉQ\bar Q production at the LHC.Comment: 4 pages, 1 figur

    Search for Bottom Counterparts of X(3872) and Y(4260) via π+πΥ\pi^+\pi^-\Upsilon

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    The X(3872) and Y(4260), both discovered in π+πJ/ψ\pi^+\pi^- J/\psi mode, are rather unusual: XcX(3872)X_c\equiv X(3872) is very narrow, while YcY(4260)Y_c \equiv Y(4260) has large Ycπ+πJ/ψY_c\to \pi^+\pi^-J/\psi width. Many models for their composition have been suggested, but perhaps discovering their bottom counterparts could shed much light on the issue. The narrow state, XbX_b may be searched for at the Tevatron via ppˉπ+πΥ+Xp\bar p \to \pi^+\pi^-\Upsilon + X, with the LHC much more promising. The state YbY_b can be searched for at B factories via radiative return e+eγISR+π+πΥe^+e^- \to \gamma_{\rm ISR} + \pi^+\pi^-\Upsilon on Υ(5S)\Upsilon(5S), or by e+eπ+πΥe^+e^- \to \pi^+\pi^-\Upsilon direct scan.Comment: 4 pages, no figures, presented at ICHEP 200

    ElectroWeak BaryoGenesis via Top Transport

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    We study electroweak baryogenesis driven by the top quark in two Higgs doublet model that allows flavor-changing neutral Higgs couplings. Taking Higgs sector couplings and the additional top Yukawa coupling ρtt\rho_{tt} to be O\mathcal{O}(1), one naturally has first order electroweak phase transition and sufficient CPCP violation to fuel the cosmic baryon asymmetry. Even if ρtt\rho_{tt} vanishes, the favor-changing coupling ρtc\rho_{tc} can still achieve baryogenesis. Phenomenological consequences such as tcht\to ch, τμγ\tau \to \mu\gamma, electron electric dipole moment, hγγh\to\gamma\gamma, and hhhhhh coupling are discussed. The extra scalars H0H^0, A0A^0 and H±H^\pm are sub-TeV in mass, and can be searched for at the LHC.Comment: 5 pages, 3 figures, to appear in proceedings of EPS-HEP2017 held July 2017 in Venic

    Effects of New Physics on CP Violation in B Decays

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    We discuss two models with 1 extra CP phase in bsb\leftrightarrow s transition. The CP phase arg(VtsVtb)\arg (V_{t^\prime s}V_{t^\prime b}) with fourth generations, previously ignored, could impact on bs+b\to s\ell^+\ell^-, ΔmBs\Delta m_{B_s} and sin2ΦBs\sin2\Phi_{B_s}, but does not affect EM and strong penguins. With SUSY at TeV scale, a right-handed ``sb~1\widetilde{sb}_{1}'' squark can be driven light by flavor mixing. It does not affect bs+b\to s\ell^+\ell^-, but can generate SϕKS<0S_{\phi K_S} < 0 while giving SηKSsin2ΦBd0.74S_{\eta^\prime K_S} \sim \sin2\Phi_{B_d} \cong0.74. BsB_s mixing and sin2ΦBs\sin2\Phi_{B_s} would likely be large, and SKSπ0γ0S_{K_S\pi^0\gamma}\neq 0 in B0K0γB^0\to K^{*0}\gamma is promising.Comment: 3 pages, 3 figures. Talk presented at EPS2003 Conference, Aachen, Germany, July 200

    (Vector) Glueballs and Charmonium Decay Revisited

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    From the 0++0^{++} glueball candidate we argue that the 11^{--} glueball OO to be near in mass to J/ψJ/\psi. This is supported by the recent null search for ψρπ,KKˉ\psi^\prime \to \rho\pi, K^*\bar K, while absence of distortion in the energy scan of J/ψρπJ/\psi \to \rho\pi indicates that ΓOΓJ/ψ\Gamma_O \gg \Gamma_{J/\psi}. OO may also play a role in the OZI violating pˉpϕγ,ϕπ\bar p p \to \phi\gamma, \phi\pi production puzzle.Comment: 3 pages, latex (with sprocl.sty), no figures; talk presented at DPF96, Minneapolis, August 10-15, 199

    P5P_5' Anomaly for Top: tZtZ' Production at LHC

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    The P5P_5' anomaly uncovered by the LHCb experiment in BKμμB \to K^*\mu\mu angular observables has motivated a possible ZZ' boson that couples to left-handed bsb \to s transitions, where a model would be gauged LμLτL_\mu - L_\tau symmetry, but direct search for such a ZZ' is not promising. Less constrained is an analogous ZZ' coupling to right-handed tct \to c transitions. Motivated by this, we study cgtZcg \to tZ' associated production at LHC, both for a generic model, and in LμLτL_\mu - L_\tau with a vector-like U quark. We also study ccˉZc\bar c \to Z' production that exists within the model. Both processes can be probed already with LHC Run 2 data, all the way up to the HL-LHC with discovery potential.Comment: 6 pages, 8 figures. Talk presented at the APS Division of Particles and Fields Meeting (DPF 2017), July 31-August 4, 2017, Fermilab. C17073

    On the gauge features of gravity on a Lie algebroid structure

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    We present the geometric formulation of gravity based on the mathematical structure of a Lie Algebroid. We show that this framework provides the geometrical setting to describe the gauge propriety of gravity.Comment: We corrected a mistake in Eq (8). This equation is only part of the review presented in the introduction and does not effect the rest of the pape

    Possibility of Large FSI Phases in Light of BKπB\to K\pi & ππ\pi\pi Data

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    After briefly reviewing how data indicated that factorization seems to work in observed two body charmless modes, {\it if one takes \gamma \gtap 90^\circ}, we point out that the K0π0K^0\pi^0 mode seems too large. This and other hints suggest that perhaps not only γ\gamma is large, but rescattering phase δ\delta could be sizable as well.Comment: 3 pages, 1 eps figure included. To appear in Proceedings of ICHEP2000, Osaka, Japan, 27 July - 2 August 200

    Strongly Enhanced Gilbert Damping in 3d Transition Metal Ferromagnet Monolayers in Contact with Topological Insulator Bi2Se3

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    Engineering Gilbert damping of ferromagnetic metal films is of great importance to exploit and design spintronic devices that are operated with an ultrahigh speed. Based on scattering theory of Gilbert damping, we extend the torque method originally used in studies of magnetocrystalline anisotropy to theoretically determine Gilbert dampings of ferromagnetic metals. This method is utilized to investigate Gilbert dampings of 3d transition metal ferromagnet iron, cobalt and nickel monolayers that are contacted by the prototypical topological insulator Bi2Se3. Amazingly, we find that their Gilbert dampings are strongly enhanced by about one order in magnitude, compared with dampings of their bulks and free-standing monolayers, owing to the strong spin-orbit coupling of Bi2Se3. Our work provides an attractive route to tailoring Gilbert damping of ferromagnetic metallic films by putting them in contact with topological insulators.Comment: 5 figures; 18 page

    On processing development for fabrication of fiber reinforced composite, part 2

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    Fiber-reinforced composite laminates are used in many aerospace and automobile applications. The magnitudes and durations of the cure temperature and the cure pressure applied during the curing process have significant consequences for the performance of the finished product. The objective of this study is to exploit the potential of applying the optimization technique to the cure cycle design. Using the compression molding of a filled polyester sheet molding compound (SMC) as an example, a unified Computer Aided Design (CAD) methodology, consisting of three uncoupled modules, (i.e., optimization, analysis and sensitivity calculations), is developed to systematically generate optimal cure cycle designs. Various optimization formulations for the cure cycle design are investigated. The uniformities in the distributions of the temperature and the degree with those resulting from conventional isothermal processing conditions with pre-warmed platens. Recommendations with regards to further research in the computerization of the cure cycle design are also addressed
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