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Topcolor in the LHC Era
Ongoing LHC searches for the standard model Higgs Boson in WW or ZZ decay
modes strongly constrain the top-Higgs state predicted in many models with new
dynamics that preferentially affects top quarks. Such a state couples strongly
to top-quarks, and is therefore produced through gluon fusion at a rate that
can be greatly enhanced relative to the rate for the standard model Higgs
boson. As we discuss in this talk, a top-Higgs state with mass less than 300
GeV is excluded at 95% CL if the associated top-pion has a mass of 150 GeV, and
the constraint is even stronger if the mass of the top-pion state exceeds the
top-quark mass or if the top-pion decay constant is a substantial fraction of
the weak scale. These results have significant implications for theories with
strong top dynamics, such as topcolor-assisted technicolor, top-seesaw models,
and certain Higgsless models
Microbial electrocatalysis with Geobacter sulfurreducens biofilm on stainless steel cathodes
Stainless steel and graphite electrodes were individually addressed and polarized at−0.60V vs. Ag/AgCl in reactors filled with a growth medium that contained 25mM fumarate as the electron acceptor and no electron donor, in order to force the microbial cells to use the electrode as electron
source. When the reactor was inoculated with Geobacter sulfurreducens, the current increased and stabilized at average values around 0.75Am−2 for graphite and 20.5Am−2 for stainless steel. Cyclic voltammetry performed at the end of the experiment indicated that the reduction started at around −0.30V vs. Ag/AgCl on stainless steel. Removing the biofilm formed on the electrode surface made the current totally disappear, confirming that the G.sulfurreducens biofilm was fully responsible for the electrocatalysis of fumarate reduction. Similar current densities were recorded when the electrodes were polarized after being kept in open circuit for several days. The reasons for the bacteria presence and survival on non-connected stainless steel coupons were discussed. Chronoamperometry experiments performed at different potential values suggested that the biofilm-driven catalysis was controlled by electrochemical kinetics. The high current density obtained, quite close to the redox potential of the fumarate/succinate couple, presents stainless steel as a remarkable material to support biocathodes
Supersymmetric radiative corrections at large tan beta
In the minimal supersymmetric extension of the Standard Model (MSSM), fermion
masses and Yukawa couplings receive radiative corrections at one loop from
diagrams involving the supersymmetric particles. The corrections to the
relation between down-type fermion masses and Yukawa couplings are enhanced by
tan beta, which makes them potentially very significant at large tan beta.
These corrections affect a wide range of processes in the MSSM, including
neutral and charged Higgs phenomenology, rare B meson decays, and
renormalization of the CKM matrix. We give a pedagogical review of the sources
and phenomenological effects of these corrections.Comment: 10 pages, 1 figure, to appear in the proceedings of 30 Years of
Supersymmetry, Minneapolis, Minnesota, October 13-27, 2000; references adde
Search for new physics via CP violation in $B_{d,s} \to l^+ l^-
It is shown that in the approximation of =1 the CP violation
in decays vanishes in SM. In a 2HDM with CP violating
phases and MSSM the CP asymmetries depend on the parameters of models and can
be as large as 40% for and 3% for . An observation of CP
asymmetry in the decays would unambiguously signal the existence of new
physics.Comment: shortened version, latex, 10 pages, 2 figures, comments adde
Oxygenic phototrophic biofilms for improved cathode performance in microbial fuel cells
The rate of oxygen reduction reaction in the cathodic chambers of microbial fuel cells (MFCs) is a typical limiting aspect of its performance. Recently, research on biocathodes has gained more interest as it allows circumventing the utilisation of exogenous and unstable mediators at a lower cost. It is shown here that the growth of oxygenic phototrophs as a biofilm, increases the current output by two fold. This was possible by forcing the biofilm to grow onto the cathode, thus, producing the oxygen directly where it was consumed. This enhancement of the cathodic efficiency was stable for over 30. days. © 2013 Elsevier B.V
Axiomatic geometrical optics, Abraham-Minkowski controversy, and photon properties derived classically
By restating geometrical optics within the field-theoretical approach, the
classical concept of a photon (and, more generally, any elementary excitation)
in arbitrary dispersive medium is introduced, and photon properties are
calculated unambiguously. In particular, the canonical and kinetic momenta
carried by a photon, as well as the two corresponding energy-momentum tensors
of a wave, are derived from first principles of Lagrangian mechanics. As an
example application of this formalism, the Abraham-Minkowski controversy
pertaining to the definitions of these quantities is resolved for linear waves
of arbitrary nature, and corrections to the traditional formulas for the photon
kinetic energy-momentum are found. Several other applications of axiomatic
geometrical optics to electromagnetic waves are also presented
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