4,036 research outputs found
Site-Specific Bioorthogonal Labeling of a G Protein-Coupled Receptor at a Genetically Encoded Azido Amino Acid
Resolving the A_{FB}^b puzzle in an extra dimensional model with an extended gauge structure
It is notorious that, contrary to all other precision electroweak data, the
forward-backward asymmetry for b quarks measured in Z decays at LEP1
is nearly three standard deviations away from the predicted value in the
Standard Model; significant deviations also occur in measurements of the
asymmetry off the Z pole. We show that these discrepancies can be resolved in a
variant of the Randall-Sundrum extra-dimensional model in which the gauge
structure is extended to to allow for
relatively light Kaluza-Klein excitations of the gauge bosons. In this
scenario, the fermions are localized differently along the extra dimension, in
order to generate the fermion mass hierarchies, so that the electroweak
interactions for the heavy third generation fermions are naturally different
from the light fermion ones. We show that the mixing between the Z boson with
the Kaluza-Klein excitations allows to explain the anomaly without
affecting (and even improving) the agreement of the other precision
observables, including the partial decay width, with experimental
data. Some implications of this scenario for the ILC are summarized.Comment: 23 pages, 5 figure
Non-standard neutrino interactions in the Zee-Babu model
We investigate non-standard neutrino interactions (NSIs) in the Zee--Babu
model. The size of NSIs predicted by this model is obtained from a full scan
over the parameter space, taking into account constraints from low-energy
experiments such as searches for lepton flavor violation (LFV) and the
requirement to obtain a viable neutrino mass matrix. The dependence on the
scale of new physics as well as on the type of the neutrino mass hierarchy is
discussed. We find that NSIs at the source of a future neutrino factory may be
at an observable level in the nu_e to nu_tau and/or nu_mu to nu_tau channels.
In particular, if the doubly charged scalar of the model has a mass in reach of
the LHC and if the neutrino mass hierarchy is inverted, a highly predictive
scenario is obtained with observable signals at the LHC, in upcoming neutrino
oscillation experiments, in LFV processes, and for NSIs at a neutrino factory.Comment: 9 pages, 4 figure
An event-driven probabilistic model of sound source localization using cochlea spikes
This work presents a probabilistic model that estimates the location of sound sources using the output spikes of a silicon cochlea such as the Dynamic Audio Sensor. Unlike previous work which estimated the source locations directly from the interaural time differences (ITDs) extracted from the timing of the cochlea spikes, the spikes are used instead to support a distribution model of the ITDs representing possible locations of sound sources. Results on noisy single speaker recordings show average accuracies of approximately 80% on detecting the correct source locations and an estimation lag of <;100ms
Non-Standard Neutrino Interactions from a Triplet Seesaw Model
We investigate non-standard neutrino interactions (NSIs) in the triplet
seesaw model featuring non-trivial correlations between NSI parameters and
neutrino masses and mixing parameters. We show that sizable NSIs can be
generated as a consequence of a nearly degenerate neutrino mass spectrum. Thus,
these NSIs could lead to quite significant signals of lepton flavor violating
decays such as \mu^- \to e^- \nu_e anti\nu_\mu and \mu^+ \to e^+ anti\nu_e
\nu_\mu at a future neutrino factory, effects adding to the uncertainty in
determination of the Earth matter density profile, as well as characteristic
patterns of the doubly charged Higgs decays observable at the Large Hadron
Collider.Comment: 4 pages, 3 figures and 1 table; v2: minor corrections, Sect. IV
revise
Non-Standard Interaction Effects at Reactor Neutrino Experiments
We study non-standard interactions (NSIs) at reactor neutrino experiments,
and in particular, the mimicking effects on \theta_13. We present generic
formulas for oscillation probabilities including NSIs from sources and
detectors. Instructive mappings between the fundamental leptonic mixing
parameters and the effective leptonic mixing parameters are established. In
addition, NSI corrections to the mixing angles \theta_13 and \theta_12 are
discussed in detailed. Finally, we show that, even for a vanishing \theta_13,
an oscillation phenomenon may still be observed in future short baseline
reactor neutrino experiments, such as Double Chooz and Daya Bay, due to the
existences of NSIs.Comment: 17 pages, 5 figures, version to appear in PL
Dissociation of H2 molecule on the {\beta}-Ga2O3 (100)B surface: The critical role of oxygen vacancy
We systematically study the dissociation of H2 molecules on the {\beta}-Ga2O3
(100)B surface, with the influences of surface oxygen vacancy being considered.
After introducing the surface oxygen vacancy, the nearest topmost O(I) atom
becomes very active, and hydrogen molecules become much easier to dissociate.Comment: 6 pages, 5 figure
Modified Zee mass matrix with zero-sum condition
We modify the Zee mass matrix by adding a real one parameter perturbation
which is purely diagonal and trace-less. We show that in this way we can
explain both solar and atmospheric neutrino oscillation data. There is a
correlation between the deviation from strict maximality of , with the emergence of a small but non-zero . We calculate
how big a value can get when we restrict ourselves within the allowed
regions of solar and atmospheric neutrino masses and mixing angles. We also
discuss the impact of a permutation symmetry on our mass matrix and show
how a small can emerge when this permutation symmetry
between the second and the third generation is broken.Comment: Version to appear in Physics Letters B. (17 pages
Sequential Transphosphorylation of the BRI1/BAK1 Receptor Kinase Complex Impacts Early Events in Brassinosteroid Signaling
SummaryBrassinosteroids (BRs) regulate plant development through a signal transduction pathway involving the BRI1 and BAK1 transmembrane receptor kinases. The detailed molecular mechanisms of phosphorylation, kinase activation, and oligomerization of the BRI1/BAK1 complex in response to BRs are uncertain. We demonstrate that BR-dependent activation of BRI1 precedes association with BAK1 in planta, and that BRI1 positively regulates BAK1 phosphorylation levels in vivo. BRI1 transphosphorylates BAK1 in vitro on specific kinase-domain residues critical for BAK1 function. BAK1 also transphosphorylates BRI1, thereby quantitatively increasing BRI1 kinase activity toward a specific substrate. We propose a sequential transphosphorylation model in which BRI1 controls signaling specificity by direct BR binding followed by substrate phosphorylation. The coreceptor BAK1 is then activated by BRI1-dependent transphosphorylation and subsequently enhances signaling output through reciprocal BRI1 transphosphorylation. This model suggests both conservation and distinct differences between the molecular mechanisms regulating phosphorylation-dependent kinase activation in plant and animal receptor kinases
Combining Direct & Indirect Kaon CP Violation to Constrain the Warped KK Scale
The Randall-Sundrum (RS) framework has a built in protection against flavour
violation, but still generically suffers from little CP problems. The most
stringent bound on flavour violation is due to epsilon_K, which is inversely
proportional to the fundamental Yukawa scale. Hence the RS epsilon_K problem
can be ameliorated by effectively increasing the Yukawa scale with a bulk
Higgs, as was recently observed in arXiv:0810.1016. We point out that
incorporating the constraint from epsilon'/\epsilon_K, which is proportional to
the Yukawa scale, raises the lower bound on the KK scale compared to previous
analyses. The bound is conservatively estimated to be 5.5 TeV, choosing the
most favorable Higgs profile, and 7.5 TeV in the two-site limit. Relaxing this
bound might require some form of RS flavour alignment. As a by-product of our
analysis, we also provide the leading order flavour structure of the theory
with a bulk Higgs.Comment: 15 pages, 2 figure
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