5,731 research outputs found

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

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

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

Using an effective potential approach, we compute two-loop radiative
corrections to the MSSM lightest ${\cal CP}$-even Higgs boson mass $M_{h^0}$ to
${\cal O}(\alpha_t^2)$ for arbitrary left-right top-squark mixing and
$\tan\beta$. We find that these corrections can increase $M_{h^0}$ by as much
as 5 GeV; assuming a SUSY scale of 1 TeV, the upper bound on the Higgs boson
mass is $M_{h^0}\approx 129\pm 5$ GeV for the top quark pole mass $175\pm 5$
GeV. We also derive an analytical approximation formula for $M_{h^0}$ 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 $h \to W^*W^*$ Decays at the Upgraded Fermilab Tevatron

We study the observability of a Standard Model-like Higgs boson at an
upgraded Fermilab Tevatron via the mode $h \to W^*W^*$. We concentrate on the
main channel $gg \to h \to W^*W^* \to l \nu l \nu$. We also find the mode
$q\bar q'\to W h \to W W^*W^* \to l^\pm \nu l^\pm \nu jj$ 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 fb$^{-1}$ the
signal should be observable at a 3$\sigma$ 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

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

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