IFAE

About: IFAE is a other organization based out in Barcelona, Spain. It is known for research contribution in the topics: Large Hadron Collider & Galaxy. The organization has 664 authors who have published 1270 publications receiving 51097 citations. The organization is also known as: Instituto de Fisica de Altas Energias & IFAE.

MAGIC observations and multiwavelength properties of the quasar 3C 279 in 2007 and 2009

Abstract: Context. 3C 279, the first quasar discovered to emit VHE gamma-rays by the MAGIC telescope in 2006, was reobserved by MAGIC in January 2007 during a major optical flare and from December 2008 to April 2009 following an alert from the Fermi space telescope on an exceptionally high gamma-ray state. Aims. The January 2007 observations resulted in a detection on January 16 with significance 5.4 sigma, corresponding to a F (>150 GeV) (3.8 +/- 0.8) x 10(-11) ph cm(-2) s(-1) while the overall data sample does not show significant signal. The December 2008-April 2009 observations did not detect the source. We study the multiwavelength behaviour of the source at the epochs of MAGIC observations, collecting quasi-simultaneous data at optical and X-ray frequencies and for 2009 also gamma-ray data from Fermi. Methods. We study the light curves and spectral energy distribution of the source. The spectral energy distributions of three observing epochs (including the February 2006, which has been previously published) are modelled with one-zone inverse Compton models and the emission on January 16, 2007 also with two zone model and with a lepto-hadronic model. Results. We find that the VHE gamma-ray emission detected in 2006 and 2007 challenges standard one-zone model, based on relativistic electrons in a jet scattering broad line region photons, while the other studied models fit the observed spectral energy distribution more satisfactorily.

Assessing lepton-flavour non-universality from B →K ∗ ℓℓ angular analyses

Abstract: The B → K ∗ μμ decay exhibits deviations with respect to Standard Model expectations and the measurement of the ratio R K hints at a violation of lepton-flavour universality in B → Kll transitions. Both effects can be understood in model-independent fits as a short-distance contribution to the Wilson coefficient C 9μ , with some room for similar contributions in other Wilson coefficients for b → sμμ transitions. We discuss how a full angular analysis of B → K ∗ ee and its comparison with B → K ∗ μμ could improve our understanding of these anomalies and help confirming their interpretation in terms of short-distance New Physics. We discuss several observables of interest in this context and provide predictions for them within the Standard Model as well as within several New Physics benchmark scenarios. We pay special attention to the sensitivity of these observables to hadronic uncertainties from SM contributions with charm loops.

Cosmological constraints from multiple probes in the Dark Energy Survey

Abstract: The combination of multiple observational probes has long been advocated as a powerful technique to constrain cosmological parameters, in particular dark energy. The Dark Energy Survey has measured 207 spectroscopically confirmed type Ia supernova light curves, the baryon acoustic oscillation feature, weak gravitational lensing, and galaxy clustering. Here we present combined results from these probes, deriving constraints on the equation of state, w, of dark energy and its energy density in the Universe. Independently of other experiments, such as those that measure the cosmic microwave background, the probes from this single photometric survey rule out a Universe with no dark energy, finding w=-0.80_{-0.11}^{+0.09}. The geometry is shown to be consistent with a spatially flat Universe, and we obtain a constraint on the baryon density of Ω_{b}=0.069_{-0.012}^{+0.009} that is independent of early Universe measurements. These results demonstrate the potential power of large multiprobe photometric surveys and pave the way for order of magnitude advances in our constraints on properties of dark energy and cosmology over the next decade.

First experimental tests with a CdTe photon counting pixel detector hybridized with a Medipix2 readout chip

Abstract: We present preliminary tests of hybrid pixel detectors consisting of the Medipix2 readout chip bump-bonded to a 1-mm-thick CdTe pixel detector. This room temperature imaging system for single photon counting has been developed within the Medipix2 European Collaboration for various imaging applications with X-rays and gamma rays, including dental radiography, mammography, synchrotron radiation, nuclear medicine, and radiation monitoring in nuclear facilities. The Medipix2 + CdTe hybrid detector features 256 /spl times/ 256 square pixels, a pitch of 55 /spl mu/m, a sensitive area of 14/spl times/14 mm/sup 2/. We analyzed the quality of the detector and bump-bonding and the response to nuclear radiation of the first CdTe hybrids. The CdTe pixel detectors, with Pt ohmic contacts, showed an ohmic response when negatively biased up to less than 60 V (electrons collection mode). Tests were also performed in holes collection mode, where a nonresistive behavior was observed above +15 V. We performed a series of imaging tests at low voltage bias with gamma radioactive sources and with an X-ray tube. Under uniform irradiation, we observed for all detectors the presence of numerous, stable structures in the form of small circles of about 200 /spl mu/m diameter, with the central pixels showing a reduced counting efficiency with respect to the periphery (in electrons counting regime). Also long filament structures have been observed. Further investigations will reveal whether they are due to an intrinsic detector response (e.g., due to Te inclusions) or to the bump-bonding process.

Angular analysis of B d 0 → K∗μ+μ− decays in pp collisions at s√=8 TeV with the ATLAS detector

Abstract: An angular analysis of the decay B-d(0) -> K*mu(+)mu(-) is presented, based on proton-proton collision data recorded by the ATLAS experiment at the LHC. The study is using 20.3 fb(-1) of integra ...