Rubin-LSST

Abstract:

We report a measurement of time-integrated CP-violation asymmetries in the resonant substructure of the three-body decay D0 to Ks pi+ pi- using CDF II data corresponding to 6.0 invfb of integrated luminosity from Tevatron ppbar collisions at sqrt(s) = 1.96 TeV. The charm mesons used in this analysis come from D*+(2010) to D0 pi+ and D*-(2010) to D0bar pi-, where the production flavor of the charm meson is determined by the charge of the accompanying pion. We apply a Dalitz-amplitude analysis for the description of the dynamic decay structure and use two complementary approaches, namely a full Dalitz-plot fit employing the isobar model for the contributing resonances and a model-independent bin-by-bin comparison of the D0 and D0bar Dalitz plots. We find no CP-violation effects and measure an asymmetry of ACP = (-0.05 +- 0.57 (stat) +- 0.54 (syst))% for the overall integrated CP-violation asymmetry, consistent with the standard model prediction.

Abstract:

In this paper, a measurement of τ polarization in W → τν decays is presented. It is measured from the energies of the decay products in hadronic τ decays with a single final state charged particle. The data, corresponding to an integrated luminosity of 24 pb⁻¹, were collected by the ATLAS experiment at the Large Hadron Collider in 2010. The measured value of the τ polarization is Pτ = −1.06±0.04 (stat) ^+0.05−0.07 (syst), in agreement with the Standard Model prediction, and is consistent with a physically allowed 95 % CL interval [−1,−0.91]. Measurements of τ polarization have not previously been made at hadron colliders.

Abstract:

This letter reports on a search for hypothetical heavy neutrinos, N, and right-handed gauge bosons, W R , in events with high transverse momentum objects which include two reconstructed leptons and at least one hadronic jet. The results were obtained from data corresponding to an integrated luminosity of 2.1 fb −1 collected in proton–proton collisions at √ s = 7 TeV with the ATLAS detector at the CERN Large Hadron Collider. No excess above the Standard Model background expectation is observed. Excluded mass regions for Majorana and Dirac neutrinos are presented using two approaches for interactions that violate lepton and lepton-flavor numbers. One approach uses an effective operator framework, the other approach is guided by the Left– Right Symmetric Model. The results described in this letter represent the most stringent limits to date on the masses of heavy neutrinos and W R bosons obtained in direct searches.

Abstract:

Dispersion in the interstellar medium is a well known phenomenon that follows a simple relationship, which has been used to predict the time delay of dispersed radio pulses since the late 1960s. We performed wide-band simultaneous observations of four pulsars with LOFAR (at 40-190 MHz), the 76-m Lovell Telescope (at 1400 MHz) and the Effelsberg 100-m Telescope (at 8000 MHz) to test the accuracy of the dispersion law over a broad frequency range. In this paper we present the results of these observations which show that the dispersion law is accurate to better than 1 part in 105 across our observing band. We use this fact to constrain some of the properties of the interstellar medium along the line-of-sight and use the lack of any aberration or retardation effects to determine upper limits on emission heights in the pulsar magnetosphere. We also discuss the effect of pulse profile evolution on our observations, and the implications that it could have for precision pulsar timing projects such as the detection of gravitational waves with pulsar timing arrays. © 2012 ESO.