5,731 research outputs found

    Effective potential calculation of the MSSM lightest CP-even Higgs boson mass

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    I summarize results of two-loop effective potential calculations of the lightest CP-even Higgs boson mass in the minimal supersymmetric standard model.Comment: 4 pages, 1 figur

    V-A Constraint on a Product of R-parity Violating Couplings

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    We study in the framework of R-parity violating supersymmetric theories the effect of R-parity violation due to the operator L_i L_j \bar{E_k} on the (V-A) structure of the muon decay. The precisely measured muon decay parameters can constrain a product of R-parity violating couplings: |\lambda_{232}\lambda_{131}| < 0.022 at the 90% CL, which is complementary to the previous limits obtained by the e-\mu universality in \tau decay.Comment: 8 pages, REVTEX, no figure

    Complete Two-loop Dominant Corrections to the Mass of the Lightest CP-even Higgs Boson in the Minimal Supersymmetric Standard Model

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    Using an effective potential approach, we compute two-loop radiative corrections to the MSSM lightest CP{\cal CP}-even Higgs boson mass Mh0M_{h^0} to O(αt2){\cal O}(\alpha_t^2) for arbitrary left-right top-squark mixing and tanβ\tan\beta. We find that these corrections can increase Mh0M_{h^0} by as much as 5 GeV; assuming a SUSY scale of 1 TeV, the upper bound on the Higgs boson mass is Mh0129±5M_{h^0}\approx 129\pm 5 GeV for the top quark pole mass 175±5175\pm 5 GeV. We also derive an analytical approximation formula for Mh0M_{h^0} which is good to a precision of \lsim 0.5 GeV for most of the parameter space and suitable to be further improved by including renormalization group resummation of leading and next-to-leading order logarithmic terms. Our final compact formula admits a clear physical interpretation: radiative corrections up to the two-loop level can be well approximated by a one-loop expression with parameters evaluated at the appropriate scales, plus a smaller finite two-loop threshold correction term.Comment: 34 pages, 8 figures. Minor typographic errors corrected. Add bottom Yukawa contributions in the Appendice

    Exploiting hWWh \to W^*W^* Decays at the Upgraded Fermilab Tevatron

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    We study the observability of a Standard Model-like Higgs boson at an upgraded Fermilab Tevatron via the mode hWWh \to W^*W^*. We concentrate on the main channel gghWWlνlνgg \to h \to W^*W^* \to l \nu l \nu. We also find the mode qqˉWhWWWl±νl±νjjq\bar q'\to W h \to W W^*W^* \to l^\pm \nu l^\pm \nu jj useful. We perform detector level simulations by making use of a Monte Carlo program SHW. Optimized searching strategy and kinematical cuts are developed. We find that with a c.m. energy of 2 TeV and an integrated luminosity of 30 fb1^{-1} the signal should be observable at a 3σ\sigma level or better for the mass range of 145 GeV < m_h < 180 GeV. For 95% confidence level exclusion, the mass reach is 135 GeV < m_h <190 GeV. We also present results of studying these channels with a model-independent parameterization. Further improvement is possible by including other channels. We conclude that the upgraded Fermilab Tevatron will have the potential to significantly advance our knowledge of Higgs boson physics.Comment: 23 pages; 15 figures; 5 table

    Shear-induced rigidity of frictional particles: Analysis of emergent order in stress space

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    Solids are distinguished from fluids by their ability to resist shear. In traditional solids, the resistance to shear is associated with the emergence of broken translational symmetry as exhibited by a non-uniform density pattern, which results from either minimizing the energy cost or maximizing the entropy or both. In this work, we focus on a class of systems, where this paradigm is challenged. We show that shear-driven jamming in dry granular materials is a collective process controlled solely by the constraints of mechanical equilibrium. We argue that these constraints lead to a broken translational symmetry in a dual space that encodes the statistics of contact forces and the topology of the contact network. The shear-jamming transition is marked by the appearance of this broken symmetry. We extend our earlier work, by comparing and contrasting real space measures of rheology with those obtained from the dual space. We investigate the structure and behavior of the dual space as the system evolves through the rigidity transition in two different shear protocols. We analyze the robustness of the shear-jamming scenario with respect to protocol and packing fraction, and demonstrate that it is possible to define a protocol-independent order parameter in this dual space, which signals the onset of rigidity.Comment: 14 pages, 17 figure