2,156 research outputs found
Boosting Higgs decays into gamma and a Z in the NMSSM
In this work we present the computation of the Higgs decay into a photon and
a boson at one-loop level in the framework of the Next-to-Minimal
Supersymmetric Standard Model (NMSSM). The numerical evaluation of this decay
width was performed within the framework of the SloopS code, orginally
developped for the Minimal Supersymmetric Standard Model (MSSM) but which was
recently extended to deal with the NMSSM. Thanks to the high level of
automation of SloopS all contributions from the various sector of the NMSSM are
consistently taken into account, in particular the non-diagonal chargino and
sfermion contributions. We then explored the NMSSM parameter space, using
HiggsBounds and HiggsSignals, to investigate to which extent these signal can
be enhanced.Comment: 14 pages, 3 figures, typos fixed, matches the public version, results
and conclusions unchange
One-loop renormalisation of the NMSSM in SloopS : 1. the neutralino-chargino and sfermion sectors
We have completed the one-loop renormalisation of the Next-to-Minimal
Supersymmetric Standard Model (NMSSM) allowing for and comparing between
different renormalisation schemes. A special attention is paid to on-shell
schemes. We study a variety of these schemes based on alternative choices of
the physical input parameters. In this paper we present our approach to the
renormalisation of the NMSSM and report on our results for the
neutralino-chargino and sfermion sectors. We will borrow some results from our
study of the Higgs sector whose full discussion is left for a separate
publication. We have implemented the set up for all the sectors of the NMSSM
within \sloops, a code for the automatic computation of one-loop corrections
initially developed for the standard model and the MSSM. Among the many
applications that allows the code, we present here the one-loop corrections to
neutralino masses and to partial widths of neutralinos and charginos into final
states with one gauge boson. One-loop electroweak and QCD corrections to the
partial widths of third generation sfermions into a fermion and a chargino or a
neutralino are also computed.Comment: 44 page
L'énumération dans la copie
Nous nous sommes interrogées sur les difficultés rencontrées par les élèves dans la tâche de copie. Nous avons tenté de déterminer le rôle de l’énumération dans la copie ; pour cela, nous avons mis en place une expérimentation qui nous a permis de mettre en avant les stratégies adoptées par quelques élèves issus d’une classe de CE1
The Sumatran earthquake impact on Earth Rotation from satellite gravimetric measurements
From the satellite gravity field measurements (mission GRACE and LAGEOS) we computed the changes in inertia moments of the Earth, which have followed the gigantic Sumatra Earthquake of December 26, 2004. Our approach is based upon the geoid height variations, which has been caused by the Earthquake. According to those gravimetric data, the pole was shifted up to 2 mas towards 90 degree East and the length of day dropped up to -5 microseconds. The phase obtained for the pole shift contradicts that one derived from seismic model
Contribution Ă l'Ă©tude de la valeur nutritive de quelques plantes naturellement abondantes en Corse
Observation of the Earth’s nutation by the VLBI: how accurate is the geophysical signal
International audienceWe compare nutation time series determined by several International VLBI Service for geodesy and astrometry (IVS) analysis centers. These series were made available through the International Earth Rotation and Reference Systems Service (IERS). We adjust the amplitudes of the main nutations, including the free motion associated with the free core nutation (FCN). Then, we discuss the results in terms of physics of the Earth’s interior. We find consistent FCN signals in all of the time series, and we provide corrections to IAU 2000A series for a number of nutation terms with realistic errors. It appears that the analysis configuration or the software packages used by each analysis center introduce an error comparable to the amplitude of the prominent corrections. We show that the inconsistencies between series have significant consequences on our understanding of the Earth’s deep interior, especially for the free inner core resonance: they induce an uncertainty on the FCN period of about 0.5 day, and on the free inner core nutation (FICN) period of more than 1000 days, comparable to the estimated period itself. Though the FCN parameters are not so much affected, a 100% error shows up for the FICN parameters and prevents from geophysical conclusions
Searching for gravitational waves with the LIGO and Virgo interferometers
The first generation of ground-based interferometric gravitational wave
detectors, LIGO, GEO and Virgo, have operated and taken data at their design
sensitivities over the last few years. The data has been examined for the
presence of gravitational wave signals. Presented here is a comprehensive
review of the most significant results. The network of detectors is currently
being upgraded and extended, providing a large likelihood for observations.
These future prospects will also be discussed.Comment: 33 pages, 4 figures, published in Comptes Rendus Physiqu
On the background estimation by time slides in a network of gravitational wave detectors
Time shifting the outputs of Gravitational Wave detectors operating in
coincidence is a convenient way to estimate the background in a search for
short duration signals. However this procedure is limited as increasing
indefinitely the number of time shifts does not provide better estimates. We
show that the false alarm rate estimation error saturates with the number of
time shifts. In particular, for detectors with very different trigger rates
this error saturates at a large value. Explicit computations are done for 2
detectors, and for 3 detectors where the detection statistic relies on the
logical ``OR'' of the coincidences of the 3 couples in the network.Comment: accepted for publication in CQ
Coincidence and coherent data analysis methods for gravitational wave bursts in a network of interferometric detectors
Network data analysis methods are the only way to properly separate real
gravitational wave (GW) transient events from detector noise. They can be
divided into two generic classes: the coincidence method and the coherent
analysis. The former uses lists of selected events provided by each
interferometer belonging to the network and tries to correlate them in time to
identify a physical signal. Instead of this binary treatment of detector
outputs (signal present or absent), the latter method involves first the
merging of the interferometer data and looks for a common pattern, consistent
with an assumed GW waveform and a given source location in the sky. The
thresholds are only applied later, to validate or not the hypothesis made. As
coherent algorithms use a more complete information than coincidence methods,
they are expected to provide better detection performances, but at a higher
computational cost. An efficient filter must yield a good compromise between a
low false alarm rate (hence triggering on data at a manageable rate) and a high
detection efficiency. Therefore, the comparison of the two approaches is
achieved using so-called Receiving Operating Characteristics (ROC), giving the
relationship between the false alarm rate and the detection efficiency for a
given method. This paper investigates this question via Monte-Carlo
simulations, using the network model developed in a previous article.Comment: Spelling mistake corrected in one author's nam
Comparison of filters for detecting gravitational wave bursts in interferometric detectors
Filters developed in order to detect short bursts of gravitational waves in
interferometric detector outputs are compared according to three main points.
Conventional Receiver Operating Characteristics (ROC) are first built for all
the considered filters and for three typical burst signals. Optimized ROC are
shown for a simple pulse signal in order to estimate the best detection
efficiency of the filters in the ideal case, while realistic ones obtained with
filters working with several ``templates'' show how detection efficiencies can
be degraded in a practical implementation. Secondly, estimations of biases and
statistical errors on the reconstruction of the time of arrival of pulse-like
signals are then given for each filter. Such results are crucial for future
coincidence studies between Gravitational Wave detectors but also with neutrino
or optical detectors. As most of the filters require a pre-whitening of the
detector noise, the sensitivity to a non perfect noise whitening procedure is
finally analysed. For this purpose lines of various frequencies and amplitudes
are added to a Gaussian white noise and the outputs of the filters are studied
in order to monitor the excess of false alarms induced by the lines. The
comparison of the performances of the different filters finally show that they
are complementary rather than competitive.Comment: 32 pages (14 figures), accepted for publication in Phys. Rev.
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