10,976 research outputs found
Consequences of Leading-Logarithm Summation for the Radiative Breakdown of Standard-Model Electroweak Symmetry
In the empirically sensible limit in which QCD, t-quark Yukawa, and
scalar-field-interaction coupling constants dominate all other Standard-Model
coupling constants, we sum all leading-logarithm terms within the perturbative
expansion for the effective potential that contribute to the extraction of the
Higgs boson mass via radiative electroweak symmetry breaking. A Higgs boson
mass of 216 GeV emerges from such terms, as well as a scalar-field-interaction
coupling constant substantially larger than that anticipated from conventional
spontaneous symmetry breaking. The sum of the effective potential's leading
logarithms is shown to exhibit a local minimum in the limit if the
QCD coupling constant is sufficiently strong, suggesting (in a multiphase
scenario) that electroweak physics may provide the mechanism for choosing the
asymptotically-free phase of QCD.Comment: latex using aip proceedings class. 8 page write-out of presentation
at MRST 2003 Conference (Syracuse
Imaging Transport Resonances in the Quantum Hall Effect
We use a scanning capacitance probe to image transport in the quantum Hall
system. Applying a DC bias voltage to the tip induces a ring-shaped
incompressible strip (IS) in the 2D electron system (2DES) that moves with the
tip. At certain tip positions, short-range disorder in the 2DES creates a
quantum dot island in the IS. These islands enable resonant tunneling across
the IS, enhancing its conductance by more than four orders of magnitude. The
images provide a quantitative measure of disorder and suggest resonant
tunneling as the primary mechanism for transport across ISs.Comment: 4 pages, 4 figures, submitted to PRL. For movies and additional
infomation, see http://electron.mit.edu/scanning/; Added scale bars to
images, revised discussion of figure 3, other minor change
Higher Order Stability of a Radiatively Induced 220 GeV Higgs Mass
The effective potential for radiatively broken electroweak symmetry in the
single Higgs doublet Standard Model is explored to four sequentially subleading
logarithm-summation levels (5-loops) in the dominant Higgs self-interaction
couplant . We augment these results with all contributing leading
logarithms in the remaining large but sub-dominant Standard Model couplants
(t-quark, QCD and gauge couplants) as well as next to
leading logarithm contributions from the largest of these, the t-quark and QCD
couplants. Order-by-order stability is demonstrated for earlier leading
logarithm predictions of an order 220 GeV Higgs boson mass in conjunction with
fivefold enhancement of the value for over that anticipated from
conventional spontaneous symmetry breaking.Comment: revtex, 6 pages. Analysis and text is expanded in revised versio
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