Observation of the decay B0 -> D0K+K- with the LHCb detector at CERN

The first observation of the decay mode B0 -> D0K+K- is presented using 0.62 fb-1 of data collected by the LHCb detector in 2011. The branching fraction is measured with respect to the topologically similar decay mode, B0 -> D0π+π-. The ratio of branching fractions is measured to be B(B0 -> D0K+K-) / B(B0 -> D0π+π-) = 0.056 ± 0.011 ± 0.007, where the first uncertainty is statistical and the second is systematic. Using the world average value for the denominator yields B(B0 -> D0K+K-) = (4.7 ± 0.9 ± 0.6 ± 0.5) x 10-5, where the third uncertainty is from B(B0 -> D0π+π-). Secondly, evidence for the B0s -> D0K+K- decay mode is presented. The branching fraction ratio with respect to B0 -> D0K+K- is found to be B(B0s -> D0K+K-) / B(B0 -> D0K+K-) = 0.90 ± 0.27 ± 0.20, where the first uncertainty is statistical and the second is systematic

First observation of Bs0 → D*s2+Xμ-ν decays

Using data collected with the LHCb detector in proton–proton collisions at a centre-of-mass energy of 7 TeV, the semileptonic decays B0s→D+sXμ−ν and B0s→D0K+Xμ−ν are detected. Two structures are observed in the D0K+ mass spectrum at masses consistent with the known Ds1(2536)+ and D∗s22573)+ mesons. The measured branching fractions relative to the total B0s semileptonic rate are B(B0s→D∗+s2Xμ−ν)/B(B0s→Xμ−ν) = (3.3±1.0±0.4)%, and B(B0s→D+s1Xμ−ν)/B(B0s→Xμ−ν) = (5.4±1.2±0.5)%, where the first uncertainty is statistical and the second is systematic. This is the first observation of the D∗+s2 state in B0s decays; we also measure its mass and width

Measurement of the Bs0-Bs0 oscillation frequency δms in Bs0→Ds-(3)π decays

The Bs0-Bs0 oscillation frequency δms is measured with 36 pb-1 of data collected in pp collisions at s=7TeV by the LHCb experiment at the Large Hadron Collider. A total of 1381 Bs0→Ds-π+ and Bs0→Ds-π+π-π + signal decays are reconstructed, with average decay time resolutions of 44 fs and 36 fs, respectively. An oscillation signal with a statistical significance of 4.6σ is observed. The measured oscillation frequency is δm s=17.63±0.11(stat)±0.02(syst)ps -1

Absolute luminosity measurements with the LHCb detector at the LHC

Absolute luminosity measurements are of general interest for colliding-beam experiments at storage rings. These measurements are necessary to determine the absolute cross-sections of reaction processes and are valuable to quantify the performance of the accelerator. Using data taken in 2010, LHCb has applied two methods to determine the absolute scale of its luminosity measurements for proton-proton collisions at the LHC with a centre-of-mass energy of 7 TeV. In addition to the classic ''van der Meer scan'' method a novel technique has been developed which makes use of direct imaging of the individual beams using beam-gas and beam-beam interactions. This beam imaging method is made possible by the high resolution of the LHCb vertex detector and the close proximity of the detector to the beams, and allows beam parameters such as positions, angles and widths to be determined. The results of the two methods have comparable precision and are in good agreement. Combining the two methods, an overal precision of 3.5% in the absolute luminosity determination is reached. The techniques used to transport the absolute luminosity calibration to the full 2010 data-taking period are presented

Observation of the suppressed ADS modes B± → [π±K-/+ π+π-]D K± and B± → [π± K-/+π+π-]Dπ±

An analysis of and B± → DK± and B± → Dπ± decays is presented where the D meson is reconstructed in the four-body final state K± π-/+π+π-. Using LHCb data corresponding to an integrated luminosity of 1.0 fb-1, first observations are made of the suppressed ADS modes B± →[π± K-/+π+π-]DK± and B± → [π± K-/+π+π-]Dπ± with a significance of 5.1 sigma and greater than 10 sigma, respectively. Measurements of CP asymmetries and CP-conserving ratios of partial widths from this family of decays are also performed. The magnitude of the ratio between the suppressed and favoured B± → DK ± amplitudes is determined to be rKB = 0.097 ± 0.011

First evidence of direct CP violation in charmless two-body decays of Bs0 mesons

Using a data sample corresponding to an integrated luminosity of 0.35  fb-1 collected by LHCb in 2011, we report the first evidence of CP violation in the decays of Bs0 mesons to K±π∓ pairs, ACP(Bs0→Kπ)= 0.27±0.08(stat)±0.02(syst), with a significance of 3.3σ. Furthermore, we report the most precise measurement of CP violation in the decays of B0 mesons to K±π∓ pairs, ACP(B0→Kπ)=-0.088±0.011(stat)±0.008(syst), with a significance exceeding 6σ

When evolution is the solution to pollution : key principles, and lessons from rapid repeated adaptation of killifish (Fundulus heteroclitus) populations

© The Author(s), 2017. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Evolutionary Applications 10 (2017): 762–783, doi:10.1111/eva.12470.For most species, evolutionary adaptation is not expected to be sufficiently rapid to buffer the effects of human-mediated environmental changes, including environmental pollution. Here we review how key features of populations, the characteristics of environmental pollution, and the genetic architecture underlying adaptive traits, may interact to shape the likelihood of evolutionary rescue from pollution. Large populations of Atlantic killifish (Fundulus heteroclitus) persist in some of the most contaminated estuaries of the United States, and killifish studies have provided some of the first insights into the types of genomic changes that enable rapid evolutionary rescue from complexly degraded environments. We describe how selection by industrial pollutants and other stressors has acted on multiple populations of killifish and posit that extreme nucleotide diversity uniquely positions this species for successful evolutionary adaptation. Mechanistic studies have identified some of the genetic underpinnings of adaptation to a well-studied class of toxic pollutants; however, multiple genetic regions under selection in wild populations seem to reflect more complex responses to diverse native stressors and/or compensatory responses to primary adaptation. The discovery of these pollution-adapted killifish populations suggests that the evolutionary influence of anthropogenic stressors as selective agents occurs widely. Yet adaptation to chemical pollution in terrestrial and aquatic vertebrate wildlife may rarely be a successful “solution to pollution” because potentially adaptive phenotypes may be complex and incur fitness costs, and therefore be unlikely to evolve quickly enough, especially in species with small population sizes.National Science Foundation Grant Numbers: DEB-1265282, OCE-1314567, DEB-1120263; National Institutes of Environmental Health Sciences Grant Numbers: R01ES021934-01, P42ES007381; Postdoctoral Research Program at the US Environmental Protection (US EPA); Office of Research and Development; Oak Ridge Institute for Science and Education (ORISE) Grant Number: DW92429801; US Department of Energ

Measurement of b-hadron branching fractions for two-body decays into charmless charged hadrons

Based on data corresponding to an integrated luminosity of 0.37 fb−1 collected by the LHCb experiment in 2011, the following ratios of branching fractions are measured: B(B0→π+π−)/B(B0→K+π−)=0.262±0.009±0.017,(fs/fd)⋅B(B0s→K+K−)/B(B0→K+π−)=0.316±0.009±0.019,(fs/fd)⋅B(B0s→π+K−)/B(B0→K+π−)=0.074±0.006±0.006,(fd/fs)⋅B(B0→K+K−)/B(B0s→K+K−)=0.018+0.008−0.007±0.009,(fs/fd)⋅B(B0s→π+π−)/B(B0→π+π−)=0.050+0.011−0.009±0.004,B(Λ0b→pπ−)/B(Λ0b→pK−)=0.86±0.08±0.05, where the first uncertainties are statistical and the second systematic. Using the current world average of B(B0→K+π−) and the ratio of the strange to light neutral B meson production f s /f d measured by LHCb, we obtain: B(B0→π+π−)=(5.08±0.17±0.37)×10−6,B(B0s→K+K−)=(23.0±0.7±2.3)×10−6,B(B0s→π+K−)=(5.4±0.4±0.6)×10−6,B(B0→K+K−)=(0.11+0.05−0.04±0.06)×10−6,B(B0s→π+π−)=(0.95+0.21−0.17±0.13)×10−6. The measurements of B(B0s→K+K−) , B(B0s→π+K−) and B(B0→K+K−) are the most precise to date. The decay mode B0s→π+π− is observed for the first time with a significance of more than 5σ

Strong constraints on the rare decays Bs0 -> μ+μ- and B0 -> μ+μ-

A search for Bs0→μ+μ- and B0→μ+μ- decays is performed using 1.0  fb-1 of pp collision data collected at √s=7  TeV 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

Search for the rare decays B0s→μ+μ− and B0→μ+μ−

A search for the decays and B0→μ+μ− is performed with 0.37 fb−1 of pp collisions at collected by the LHCb experiment in 2011. The upper limits on the branching fractions are and B(B0→μ+μ−)<3.6×10−9 at 95% confidence level. A combination of these results with the LHCb limits obtained with the 2010 dataset leads to and B(B0→μ+μ−)<3.2×10−9 at 95% confidence level