36,670 research outputs found
Spin Observables in Transition-Distribution-Amplitude Studies
Exclusive hadronic reactions with a massive lepton pair (l^+l^-) in the final
state will be measured with PANDA at GSI-FAIR and with Compass at CERN, both in
p+p-bar -> l^+l^-+pi and pi+N -> N'+l^+l^-. Similarly, electroproduction of a
meson in the backward region will be studied at JLAB. We discuss here how the
spin structure of the amplitude for such processes will enable us to
disentangle various mechanisms. For instance, target-transverse-spin
asymmetries are specific of a partonic description, where the amplitude is
factorised in terms of baryon to meson or meson to baryon Transition
Distribution Amplitudes (TDAs) as opposed to what is expected from
baryon-exchange contributions.Comment: Contributed to the 19th International Spin Physics Symposium (SPIN
2010), September 27 - October 2, 2010, Juelich, Germany. 8 pages, 7 figures,
uses jpconf.cls, jpconf11.clo, iopams.sty (included
Status of the joint LIGO--TAMA300 inspiral analysis
We present the status of the joint search for gravitational waves from
inspiraling neutron star binaries in the LIGO Science Run 2 and TAMA300 Data
Taking Run 8 data, which was taken from February 14 to April 14, 2003, by the
LIGO and TAMA collaborations. In this paper we discuss what has been learned
from an analysis of a subset of the data sample reserved as a ``playground''.
We determine the coincidence conditions for parameters such as the coalescence
time and chirp mass by injecting simulated Galactic binary neutron star signals
into the data stream. We select coincidence conditions so as to maximize our
efficiency of detecting simulated signals. We obtain an efficiency for our
coincident search of 78 %, and show that we are missing primarily very distant
signals for TAMA300. We perform a time slide analysis to estimate the
background due to accidental coincidence of noise triggers. We find that the
background triggers have a very different character from the triggers of
simulated signals.Comment: 10 page, 8 figures, accepted for publication in Classical and Quantum
Gravity for the special issue of the GWDAW9 Proceedings ; Corrected typos,
minor change
Vetoes for Inspiral Triggers in LIGO Data
Presented is a summary of studies by the LIGO Scientific Collaboration's
Inspiral Analysis Group on the development of possible vetoes to be used in
evaluation of data from the first two LIGO science data runs. Numerous
environmental monitor signals and interferometer control channels have been
analyzed in order to characterize the interferometers' performance. The results
of studies on selected data segments are provided in this paper. The vetoes
used in the compact binary inspiral analyses of LIGO's S1 and S2 science data
runs are presented and discussed.Comment: Submitted to Classical and Quantum Gravity for the GWDAW-8
proceeding
Fluctuation characteristics of the TCV snowflake divertor measured with high speed visible imaging
Tangentially viewing fast camera footage of the low-field side snowflake
minus divertor in TCV is analysed across a four point scan in which the
proximity of the two X-points is varied systematically. The motion of
structures observed in the post- processed movie shows two distinct regions of
the camera frame exhibiting differing patterns. One type of motion in the outer
scrape-off layer remains present throughout the scan whilst the other, apparent
in the inner scrape-off layer between the two nulls, becomes increasingly
significant as the X-points contract towards one another. The spatial structure
of the fluctuations in both regions is shown to conform to the equilibrium
magnetic field. When the X-point gap is wide the fluctuations measured in the
region between the X-points show a similar structure to the fluctuations
observed above the null region, remaining coherent for multiple toroidal turns
of the magnetic field and indicating a physical connectivity of the
fluctuations between the upstream and downstream regions. When the X-point gap
is small the fluctuations in the inner scrape-off layer between the nulls are
decorrelated from fluctuations upstream, indicating local production of
filamentary structures. The motion of filaments in the inter-null region
differs, with filaments showing a dominantly poloidal motion along magnetic
flux surfaces when the X-point gap is large, compared to a dominantly radial
motion across flux-surfaces when the gap is small. This demonstrates an
enhancement to cross-field tranport between the nulls of the TCV low-field-side
snowflake minus when the gap between the nulls is small.Comment: Accepted for publication in Plasma Physics and Controlled Fusio
The magnetic field of the double-lined spectroscopic binary system HD 5550
(Abridged) In the framework of the BinaMicS project, we have begun a study of
the magnetic properties of a sample of intermediate-mass and massive
short-period binary systems, as a function of binarity properties. We report in
this paper the characterisation of the magnetic field of HD 5550, a
double-lined spectroscopic binary system of intermediate-mass, using
high-resolution spectropolarimetric Narval observations of HD 5550. We first
fit the intensity spectra using Zeeman/ATLAS9 LTE synthetic spectra to estimate
the effective temperatures, microturbulent velocities, and the abundances of
some elements of both components, as well as the light-ratio of the system. We
then fit the least-square deconvolved profiles to determine the radial and
projected rotational velocities of both stars. We then analysed the shape and
evolution of the LSD profiles using the oblique rotator model to
characterise the magnetic fields of both stars.
We confirm the Ap nature of the primary, previously reported in the
literature, and find that the secondary displays spectral characteristics
typical of an Am star. While a magnetic field is clearly detected in the lines
of the primary, no magnetic field is detected in the secondary, in any of our
observation. If a dipolar field were present at the surface of the Am star, its
polar strength must be below 40 G. The faint variability observed in the Stokes
profiles of the Ap star allowed us to propose a rotation period of
d, close to the orbital period (6.82 d),
suggesting that the star is synchronised with its orbit. By fitting the
variability of the profiles, we propose that the Ap component hosts a
dipolar field inclined with the rotation axis at an angle
and a polar strength G. The field strength is
the weakest known for an Ap star.Comment: 13 pages, 12 figures, accepted for publication in Astronomy &
Astrophysic
An alternative heavy Higgs mass limit
After commenting on the present value of the Higgs particle mass from
radiative corrections, we explore the phenomenological implications of an
alternative, non-perturbative renormalization of the scalar sector where the
mass of the Higgs particle does not represent a measure of observable
interactions at the Higgs mass scale. In this approach the Higgs particle could
be very heavy, even heavier than 1 TeV, and remain nevertheless a relatively
narrow resonance.Comment: 17 pages. Version accepted for publication in Journal of Physics
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