527 research outputs found
QCD sum rules analysis of the rare B_c \rar X\nu\bar{\nu} decays
Taking into account the gluon correction contributions to the correlation
function, the form factors relevant to the rare B_c \rar X \nu\bar{\nu}
decays are calculated in the framework of the three point QCD sum rules, where
stands for axial vector particle, , and vector particles,
. The total decay width as well as the branching ratio of these
decays are evaluated using the dependent expressions of the form factors.
A comparison of our results with the predictions of the relativistic
constituent quark model is presented.Comment: 21 Pages, 2 Figures and 5 Table
Scanning Fourier Spectroscopy: A microwave analog study to image transmission paths in quantum dots
We use a microwave cavity to investigate the influence of a movable absorbing
center on the wave function of an open quantum dot. Our study shows that the
absorber acts as a position-selective probe, which may be used to suppress
those wave function states that exhibit an enhancement of their probability
density near the region where the impurity is located. For an experimental
probe of this wave function selection, we develop a technique that we refer to
as scanning Fourier spectroscopy, which allows us to identify, and map out, the
structure of the classical trajectories that are important for transmission
through the cavity.Comment: 4 pages, 5 figure
Light cone QCD sum rules study of the semileptonic heavy and transitions to and baryons
The semileptonic decays of heavy spin--1/2, and
baryons to the light spin-- 1/2, and baryons are investigated
in the framework of the light cone QCD sum rules. In particular, using the most
general form of the interpolating currents for the heavy baryons as well as the
distribution amplitudes of the and baryons, we calculate all
form factors entering the matrix elements of the corresponding effective
Hamiltonians in full QCD. Having calculated the responsible form factors, we
evaluate the decay rates and branching fractions of the related transitions.Comment: 30 Pages, 5 Figures and 18 Table
Extragalactic Sources for Ultra High Energy Cosmic Ray Nuclei
In this article we examine the hypothesis that the highest energy cosmic rays
are complex nuclei from extragalactic sources. Under reasonable physical
assumptions, we show that the nearby metally rich starburst galaxies (M82 and
NGC 253) can produce all the events observed above the ankle. This requires
diffusion of particles below eV in extragalactic magnetic fields nG. Above eV, the model predicts the presence of
significant fluxes of medium mass and heavy nuclei with small rate of change of
composition. Notwithstanding, the most salient feature of the
starburst-hypothesis is a slight anisotropy induced by iron debris just before
the spectrum-cutoff.Comment: To appear in Phys. Rev. D, reference adde
Unparticle physics effects in (Lambda_b -> Lambda + missing energy) processes
We study unparticle physics effects in (Lambda_b -> Lambda + missing energy)
decay with polarized and baryons. The sensitivity of the
branching ratio of this decay and polarizations of (Lambda_b) and (Lambda)
baryons on the scale dimension d_U and effective cut-off parameter (Lambda_U)
are discussed.Comment: 17 pages, 6 figure
Conversations on grief and hope: A collaborative autoethnographic account exploring the lifeworlds of international youth engaged with climate action
This paper explores the lifeworlds of international youth involved in climate and/or environmental social action, narratives that have been largely absent from a literature that has tended to focus on ‘traditional’ youth activists located in the urban Global North. Written as a novel collaborative autoethnography involving youth as co-authors, the paper a) collectively reflects on the stories of youth from different countries and cultures on their journeys towards climate action, and b) foregrounds an emotional framing to examine these experiences. The youth co-authors, whose experiences are the focus of this paper, form part of innovative international Youth Advisory Board, set up to provide peer support to youth new to climate and environmental social action, as part of our British Academy Youth Futures-funded participatory action research project. We examine the youth’s narratives exploring opportunities and barriers they have navigated, their inspirations and the intersections with a range of other socio-cultural factors
Prediction of Neutrino Fluxes in the NOMAD Experiment
The method developed for the calculation of the flux and composition of the
West Area Neutrino Beam used by NOMAD in its search for neutrino oscillations
is described. The calculation is based on particle production rates computed
using a recent version of FLUKA and modified to take into account the cross
sections measured by the SPY and NA20 experiments. These particles are
propagated through the beam line taking into account the material and magnetic
fields they traverse. The neutrinos produced through their decays are tracked
to the NOMAD detector. The fluxes of the four neutrino flavours at NOMAD are
predicted with an uncertainty of about 8% for nu(mu) and nu(e), 10% for
antinu(mu), and 12% for antinu(e). The energy-dependent uncertainty achieved on
the R(e, mu) prediction needed for a nu(mu)->nu(e) oscillation search ranges
from 4% to 7%, whereas the overall normalization uncertainty on this ratio is
4.2%.Comment: 43 pages, 20 figures. Submitted to Nucl. Phys.
A Study of Strange Particles Produced in Neutrino Neutral Current Interactions in the NOMAD Experiment
Results of a detailed study of strange particle production in neutrino
neutral current interactions are presented using the data from the NOMAD
experiment. Integral yields of neutral strange particles (K0s, Lambda,
Lambda-bar) have been measured. Decays of resonances and heavy hyperons with an
identified K0s or Lambda in the final state have been analyzed. Clear signals
corresponding to K* and Sigma(1385) have been observed. First results on the
measurements of the Lambda polarization in neutral current interactions have
been obtained.Comment: Accepted for publication in Nuclear Physics B as a rapid
communicatio
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