5,991 research outputs found
Space based microlensing planet searches
The discovery of extra-solar planets is arguably the most exciting
development in astrophysics during the past 15 years, rivalled only by the
detection of dark energy. Two projects unite the communities of exoplanet
scientists and cosmologists: the proposed ESA M class mission EUCLID and the
large space mission WFIRST, top ranked by the Astronomy 2010 Decadal Survey
report. The later states that: "Space-based microlensing is the optimal
approach to providing a true statistical census of planetary systems in the
Galaxy, over a range of likely semi-major axes". They also add: "This census,
combined with that made by the Kepler mission, will determine how common
Earth-like planets are over a wide range of orbital parameters". We will
present a status report of the results obtained by microlensing on exoplanets
and the new objectives of the next generation of ground based wide field imager
networks. We will finally discuss the fantastic prospect offered by space based
microlensing at the horizon 2020-2025.Comment: 8 pages, Proceedings to the ROPACS meeting "Hot Planets and Cool
Stars" (Nov. 2012, Garching), invited contributio
Measurement of J/Psi production in continuum e+e- annihilations near the Upsilon(4s) with BABAR detector
Charmed-B decays at BaBar
We present recent results on charmed-B decays using data collected by the BaBa
Measurement of the CKM-angle gamma at BABAR
The authors present the results of the measurements employed by the BABAR Collaboration, to determine the value of the Cabibbo-Kobayashi-Maskawa (CKM) CP-violating phase {gamma} ({triple_bond} arg [-V{sub ud}V*{sub ub}/V{sub cd}V*{sub cb}]). These measurements are based on the studies performed with the charged B-decays B{sup -} {yields} {tilde D}{sup 0} K{sup -}, B{sup -} {yields} {tilde D}*{sup 0} K*{sup -}, where {tilde D}{sup 0} indicates either a D{sup 0} or a {bar D}{sup 0} meson. A sample of about 230 million B{bar B} pairs collected by the BABAR detector [1], at the PEP-II asymmetric-energy e{sup +}e{sup -} collider at SLAC, is used
Recent results from BABAR
We present recent results on bottomonium spectroscopy, rare neutral D mesons decays, and semi-leptonic Bs mesons decays. They are based on datasets collected at the Υ(2S), Υ(3S), and Υ(4S) resonances and slightly below and above
(up to twice the Λb mass) by the BABAR detector at the PEP-II storage rings at SLAC from year 2000 to 2008. All the results presented here are preliminary. A search of ηb(1S) and ηb(2S) quarkonia is performed in radiative transitions using an experimental technique employing converted γ rays in the Υ(2S) and Υ(3S) decays. The hb(1P) state is searched in the Υ(3S) → hb(1P)π0/π+π− decays, and an evidence of signal is seen in the channel with a neutral pion. A search of the rare FCNC D0 → γγ decay is presented and the channel D0 → π0π0 is accurately measured. Finally, we present a study of the semi-leptonic branching ratio of the Bs mesons and of the fs fraction, the production of Bs mesons. It is based on the very last BABAR dataset collected in 2008 and corresponding to an energy scan above the Υ(4S) resonances performed at PEP-II
Predictions of selected flavour observables within the Standard Model
This letter gathers a selection of Standard Model predictions issued from the
metrology of the CKM parameters performed by the CKMfitter group. The selection
includes purely leptonic decays of neutral and charged B, D and K mesons. In
the light of the expected measurements from the LHCb experiment, a special
attention is given to the radiative decay modes of B mesons as well as to the
B-meson mixing observables, in particular the semileptonic charge asymmetries
a^d,s_SL which have been recently investigated by the D0 experiment at
Tevatron. Constraints arising from rare kaon decays are addressed, in light of
both current results and expected performances of future rare kaon experiments.
All results have been obtained with the CKMfitter analysis package, featuring
the frequentist statistical approach and using Rfit to handle theoretical
uncertainties.Comment: 8 pages, 1 figure, 2 tables. Typos corrected and discussion of
agreement between SM and data update
Observation of the Decay B^-→D_s^((*)+)K^-ℓ^-ν̅ _ℓ
We report the observation of the decay B^- → D_s^((*)+)K^-ℓ^-ν̅ _ℓ based on 342  fb^(-1) of data collected at the Υ(4S) resonance with the BABAR detector at the PEP-II e^+e^- storage rings at SLAC. A simultaneous fit to three D_s^+ decay chains is performed to extract the signal yield from measurements of the squared missing mass in the B meson decay. We observe the decay B^- → D_s^((*)+)K^-ℓ^-ν̅ _ℓ with a significance greater than 5 standard deviations (including systematic uncertainties) and measure its branching fraction to be B(B^- → D_s^((*)+)K^-ℓ^-ν̅ _ℓ)=[6.13_(-1.03)^(+1.04)(stat)±0.43(syst)±0.51(B(D_s))]×10^(-4), where the last error reflects the limited knowledge of the D_s branching fractions
Exploring the parameter space of texture 4 zero quark mass matrices
We have attempted to extend the parameter space of the elements of the
texture 4 zero Hermitian quark mass matrices, to include the case of `weak
hierarchy' amongst them along with the usually considered `strong hierarchy'
case. This has been carried out by giving wide variation to the hierarchy
defining parameters D_U and D_D, having implications for the structural
features of the mass matrices. We find that not only the weakly hierarchical
mass matrices are able to reproduce the strongly hierarchical mixing angles but
also both the phases having their origin in the mass matrices have to be non
zero to achieve compatibility of these matrices with recent quark mixing data.
Further noting the difference between the exclusive and inclusive values of
V_ub, we have carried out separate analyses corresponding to these.Comment: 13 pages, 4 figures, version accepted for publication in Journal Of
Physics
Preliminary results for RR Lyrae stars and Classical Cepheids from the Vista Magellanic Cloud (VMC) Survey
The Vista Magellanic Cloud (VMC, PI M.R. Cioni) survey is collecting
-band time series photometry of the system formed by the two Magellanic
Clouds (MC) and the "bridge" that connects them. These data are used to build
-band light curves of the MC RR Lyrae stars and Classical Cepheids and
determine absolute distances and the 3D geometry of the whole system using the
-band period luminosity (), the period - luminosity - color ()
and the Wesenhiet relations applicable to these types of variables. As an
example of the survey potential we present results from the VMC observations of
two fields centered respectively on the South Ecliptic Pole and the 30 Doradus
star forming region of the Large Magellanic Cloud. The VMC -band light
curves of the RR Lyrae stars in these two regions have very good photometric
quality with typical errors for the individual data points in the range of
0.02 to 0.05 mag. The Cepheids have excellent light curves (typical
errors of 0.01 mag). The average magnitudes derived for both types
of variables were used to derive relations that are in general good
agreement within the errors with the literature data, and show a smaller
scatter than previous studies.Comment: 7 pages, 6 figure. Accepted for publication in Astrophysics and Space
Science. Following a presentation at the conference "The Fundamental Cosmic
Distance Scale: State of the Art and the Gaia Perspective", Naples, May 201
Note on the generalized Hansen and Laplace coefficients
Recently, Breiter et al (2004) reported the computation of Hansen
coefficients for non integer values of . In fact, the
Hansen coefficients are closely related to the Laplace , and
generalized Laplace coefficients (Laskar and Robutel, 1995)
that do not require to be integers. In particular, the coefficients
X_0^{\g,m} have very simple expressions in terms of the usual Laplace
coefficients b_{\g+2}^{(m)}, and all their properties derive easily from the
known properties of the Laplace coefficients.Comment: 9/11/200
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