1,552 research outputs found
Coupling spans of the Higgs-like boson
Using the LHC and Tevatron data, we set upper and lower limits on the total
width of the Higgs-like boson. The upper limit is based on the well-motivated
assumption that the Higgs coupling to a W or Z pair is not much larger than in
the Standard Model. These width limits allow us to convert the rate
measurements into ranges for the Higgs couplings to various particles. A
corollary of the upper limit on the total width is an upper limit on the
branching fraction of exotic Higgs decays. Currently, this limit is 47% at the
95% CL if the electroweak symmetry is broken only by doublets.Comment: 18 pages, 2 figures; v2: Minor clarifications, references adde
New and Improved Superstring Phenomenology
Recent developments in string theory have important implications for
cosmology. Topics discussed here are inflation, the cosmological constant,
smoothing of cosmological singularities, and dark matter from parallel
universes. Talk presented at the International Workshop on Particle Physics and
the Early Universe (COSMO-98), 15-20 Nov, Asilomar, Monterey, CA.Comment: 9 page
Ultrahigh-energy neutrino flux as a probe of large extra-dimensions
A suppression in the spectrum of ultrahigh-energy (UHE, >= 10^{18} eV)
neutrinos will be present in extra-dimensional scenarios, due to enhanced
neutrino-antineutrino annihilation processes with the supernova relic
neutrinos. In the n>4 scenario, being n the number of extra dimensions,
neutrinos can not be responsible for the highest energy events observed in the
UHE cosmic ray spectrum. A direct implication of these extra-dimensional
interactions would be the absence of UHE neutrinos in ongoing and future
neutrino telescopes.Comment: JCAP accepted version. Included 5, 6 and 7 extra-dimensional cases,
and 2 new figures. The conclusion remains unchanged that UHE neutrino flux
would be suppressed in large extra-dimensional model
Beyond the Standard Model
Six major frameworks have emerged attempting to describe particle physics
beyond the Standard Model. Despite their different theoretical genera, these
frameworks have a number of common phenomenological features and problems.
While it will be possible (and desirable) to conduct model-independent searches
for new physics at the LHC, it is equally important to develop robust methods
to discriminate between BSM 'look-alikes'.Comment: 10 pages, 5 figures, Lectures given at the 2009 European School of
High-Energy Physics, Bautzen, Germany, 14-27 Jun 200
Moriond Electroweak 2006: Theory Summary
A concise look at the big picture of particle physics, including the status
of the Standard Model, neutrinos, supersymmetry, extra dimensions and
cosmology. Based upon the theoretical summary presented at the XLIst Rencontres
de Moriond on Electroweak Interactions and Unified Theories, La Thuile, 11-18
March 2006.Comment: 12 pages, 5 figure
The Standard Model: Alchemy and Astrology
An brief unconventional review of Standard Model physics, containing no
plots.Comment: 12 pages, 0 figures, review talk from "Physics at LHC", Krakow, 3-8
July 200
The Shape of Gravity
In a nontrivial background geometry with extra dimensions, gravitational
effects will depend on the shape of the Kaluza-Klein excitations of the
graviton. We investigate a consistent scenario of this type with two positive
tension three-branes separated in a five-dimensional Anti-de Sitter geometry.
The graviton is localized on the ``Planck'' brane, while a gapless continuum of
additional gravity eigenmodes probe the {\it infinitely} large fifth dimension.
Despite the background five-dimensional geometry, an observer confined to
either brane sees gravity as essentially four-dimensional up to a
position-dependent strong coupling scale, no matter where the brane is located.
We apply this scenario to generate the TeV scale as a hierarchically suppressed
mass scale. Arbitrarily light gravitational modes appear in this scenario, but
with suppressed couplings. Real emission of these modes is observable at future
colliders; the effects are similar to those produced by {\it six} large
toroidal dimensions.Comment: 8 pages, 1 figur
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