6,153 research outputs found
Anomalous and Diboson Resonances at the LHC
We propose novel collider searches which can significantly improve the LHC
reach to new gauge bosons with mixed anomalies with the electroweak (EW)
gauge group. Such a necessarily acquires a Chern-Simons coupling to the EW
gauge bosons and these couplings can drive both exotic decays into
if the new gauge boson is sufficiently light, as well as decays
into EW gauge bosons.While the exotic decay rate of the heavy into
is too small to be observed at the LHC, for a light , we show
the potential of a lepton jet search in association with a photon to probe the
rare decay .Comment: 17 pages, 4 figures. v2: equation corrected, main results in Section
4 unchanged, accepted for publication in JHE
Leptonic Pion Decay And Physics Beyond The Electroweak Standard Model
The ratio of branching ratios in leptonic pion decay is a powerfully
sensitive probe of new interactions beyond the electroweak standard model. This
is due to the chirality suppression of the standard model amplitude for the
decay, which results in a precise prediction for the ratio, and suppressed
amplitudes for new contributions to interfere with. We calculate, including QCD
corrections, the contributions to arising from a broad selection of
standard model extensions to which it is sensitive, including: R-parity
violating interactions in supersymmetric theories, theories with light
(electroweak scale) leptoquark degrees of freedom, non-minimal models of extra
doublet Higgs bosons, models in which the quarks and leptons are composite both
with and without supersymmetry, and models with strong TeV scale gravitational
interactions. Comparing with existing measurements of we provide
limits on each of these classes of models; our calculations also represent
state of the art theoretical benchmarks against which the results from the
upcoming round of leptonic pion decay experiments may be compared.Comment: 31 pages, 3 figure
Opportunistic Spectrum Sharing using Dumb Basis Patterns: The Line-of-Sight Interference Scenario
We investigate a spectrum-sharing system with non-severely faded mutual
interference links, where both the secondary-to-primary and
primary-to-secondary channels have a Line-of-Sight (LoS) component. Based on a
Rician model for the LoS channels, we show, analytically and numerically, that
LoS interference hinders the achievable secondary user capacity. This is caused
by the poor dynamic range of the interference channels fluctuations when a
dominant LoS component exists. In order to improve the capacity of such system,
we propose the usage of an Electronically Steerable Parasitic Array Radiator
(ESPAR) antenna at the secondary terminals. An ESPAR antenna requires a single
RF chain and has a reconfigurable radiation pattern that is controlled by
assigning arbitrary weights to M orthonormal basis radiation patterns. By
viewing these orthonormal patterns as multiple virtual dumb antennas, we
randomly vary their weights over time creating artificial channel fluctuations
that can perfectly eliminate the undesired impact of LoS interference. Because
the proposed scheme uses a single RF chain, it is well suited for compact and
low cost mobile terminals
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