Observation of CP violation in B±→DK± decays
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics 712:3 (2012) 203-212
Abstract:
An analysis of B±→DK± and B±→Dπ± decays is presented where the D meson is reconstructed in the two-body final states: K±π∓, K+K- and π+π-. Using 1.0 fb-1 of s=7TeV pp collisions, measurements of several observables are made including the first observation of the suppressed mode B±→[π±K∓]DK± CP violation in B±→DK± decays is observed with 5.8σ significance. © 2012 CERN.Strong constraints on the rare decays Bs0→μ +μ - and B0→μ +μ -
Physical Review Letters 108:23 (2012)
Abstract:
A search for Bs0→μ +μ - and B0→μ +μ - decays is performed using 1.0fb -1 of pp collision data collected at √s=7TeV with the LHCb experiment at the Large Hadron Collider. For both decays, the number of observed events is consistent with expectation from background and standard model signal predictions. Upper limits on the branching fractions are determined to be B(Bs0→μ +μ -)<4.5(3.8)×10 -9 and B(B0→μ +μ -)<1.0(0.81)×10 -9 at 95% (90%) confidence level. © 2012 CERN.Constraints on brittle field exhumation of the Everest-Makalu section of the Greater Himalayan Sequence: Implications for models of crustal flow
Tectonics 31:3 (2012)
Abstract:
New apatite and zircon fission track (FT) data from the summit slopes of Everest and along the Barun, Arun, Dudh Kosi, and Kangshung valleys that drain the Everest and Makalu massifs cover a vertical sample transect of almost 8000m of the Eastern Nepal Greater Himalayan Sequence (GHS). Apatite FT ages range from 0.9±0.3Ma to 3.1±0.3Ma in the GHS with ages increasing systematically with elevation. Apatite FT ages in the Everest Series and summit Ordovician limestones are much older, up to 30.5±5.1Ma. Zircon FT ages from the GHS range from 3.8±0.4Ma to 16.3±0.8Ma. The brittle exhumation rates calculated from these data show the GHS was exhumed, since ∼9Ma, at an average rate of 1.0±0.2mm/a. Pliocene exhumation rates are higher at 1.7±0.3mm/a. These values are not significantly different from the estimate of ductile exhumation rates of 1.8mm/a recorded by metamorphic minerals undergoing decompression between 18.7 and 15.6Ma but are well below the values (up to 10mm/a) used by thermomechanical models for ductile channel flow in the GHS. If representative of the GHS these models will therefore require further tuning. Higher exhumation rates in the Pliocene have also been observed in other parts of the Himalaya and points to a regional cause, likely increased erosion due to the onset of late Pliocene-Pleistocene glaciation of the high Himalaya. Copyright © 2012 by the American Geophysical Union.Measurement of Υ{hooked} production in pp collisions at √ s = 7TeV
European Physical Journal C 72:6 (2012) 1-12
Abstract:
The production of Υ{hooked}(1S), Υ{hooked}(2S) and Υ{hooked}(3S) mesons in proton-proton collisions at the centre-of-mass energy of √ s = 7TeV is studied with the LHCb detector. The analysis is based on a data sample of 25 pb-1 collected at the Large Hadron Collider. The Υ{hooked} mesons are reconstructed in the decay mode Υ{hooked}→μ+μ- and the signal yields are extracted from a fit to the μ+μ- invariant mass distributions. The differential production cross-sections times dimuon branching fractions are measured as a function of the Υ{hooked} transverse momentum pOpposite-side flavour tagging of B mesons at the LHCb experiment
European Physical Journal C 72:6 (2012) 1-16