6,856 research outputs found
Contributions to the width difference in the neutral system from hadronic decays
Recent studies of several multi-body meson decays have revealed that
the final states are dominantly -even. However, the small value of the
width difference between the two physical eigenstates of the
- system indicates that the total widths of decays to
-even and -odd final states should be the same to within about a
percent. The known contributions to the width difference from hadronic
decays are discussed, and it is shown that an apparent excess of
quasi--even modes is balanced, within current uncertainty, by interference
effects in quasi-flavour-specific decays. Decay modes which may significantly
affect the picture with improved measurements are considered.Comment: 17 pages including 3 tables. v2: Updated with published version
including new comments in summar
Observation of the rare decay B+ -> K+Ï0Ï0 and measurement of the quasi-two-body contributions B+ -> K*(892)+Ï0, B+ -> f0(980)K+, and B+ -> Ïc0K+
We report an analysis of charmless hadronic decays of charged B mesons to the final state K(+) pi(0)pi(0), using a data sample of (470.9 +/- 2.8) x 10(6) B (B) over bar events collected with the BABAR detector at the Y(4S) resonance. We observe an excess of signal events, with a significance above 10 standard deviations including systematic uncertainties, and measure the branching fraction and CP asymmetry to be B(B(+) -> K(+) pi(0)pi(0)) = (16.2 +/- 1.2 +/- 1.5) x 10(-6) and A(CP)(B(+) -> K(+) pi(0)pi(0)) = -0.06 +/- 0.06 +/- 0.04, where the uncertainties are statistical and systematic, respectively. Additionally, we study the contributions of the B(+) -> K*(892)(+) pi(0), B(+) -> f(0)(980)K(+), and B(+) -> chi(c0)K(+) quasi-two-body decays. We report the world's best measurements of the branching fraction and CP asymmetry of the B(+) -> K(+) pi(0)pi(0) and B(+) -> K(+)(892)(+) pi(0) channels
Translational Entanglement of Dipole-Dipole Interacting Atoms in Optical Lattices
We propose and investigate a realization of the position- and
momentum-correlated Einstein-Podolsky-Rosen (EPR) states [Phys. Rev. 47, 777
(1935)] that have hitherto eluded detection. The realization involves atom
pairs that are confined to adjacent sites of two mutually shifted optical
lattices and are entangled via laser-induced dipole-dipole interactions. The
EPR "paradox" with translational variables is then modified by
lattice-diffraction effects, and can be verified to a high degree of accuracy
in this scheme.Comment: 4 pages, 3 figures, to be published in PR
Distinct subpopulations of enteric neuronal progenitors defined by time of development, sympathoadrenal lineage markers and Mash-1-dependence
Enteric and sympathetic neurons have previously been proposed to be lineally related. We present independent lines of evidence that suggest that enteric neurons arise from at least two lineages, only one of which expresses markers in common with sympathoadrenal cells. In the rat, sympathoadrenal markers are expressed, in the same order as in sympathetic neurons, by a subset of enteric neuronal precursors, which also transiently express tyrosine hydroxylase. If this precursor pool is eliminated in vitro by complement-mediated lysis, enteric neurons continue to develop; however, none of these are serotonergic. In the mouse, the Mash-1â/â mutation, which eliminates sympathetic neurons, also prevents the development of enteric serotonergic neurons. Other enteric neuronal populations, however, including those that contain calcitonin gene related peptide are present. Enteric tyrosine hydroxylase-containing cells co-express Mash-1 and are eliminated by the Mash-1â/â mutation, consistent with the idea that in the mouse, as in the rat, these precursors generate serotonergic neurons. Serotonergic neurons are generated early in development, while calcitonin gene related peptide-containing enteric neurons are generated much later. These data suggest that enteric neurons are derived from at least two progenitor lineages. One transiently expresses sympathoadrenal markers, is Mash-1-dependent, and generates early-born enteric neurons, some of which are serotonergic. The other is Mash-1-independent, does not express sympathoadrenal markers, and generates late-born enteric neurons, some of which contain calcitonin gene related peptide
Measurement of the Bs0-Bs0 oscillation frequency ÎŽms in Bs0âDs-(3)Ï decays
The Bs0-Bs0 oscillation frequency ÎŽms 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 Bs0âDs-Ï+ and Bs0âDs-Ï+Ï-Ï + signal decays are reconstructed, with average decay time resolutions of 44 fs and 36 fs, respectively. An oscillation signal with a statistical significance of 4.6Ï is observed. The measured oscillation frequency is ÎŽm s=17.63±0.11(stat)±0.02(syst)ps -1
First determination of the content of and updated determination of the contents of and
Quantum-correlated decays collected by the CLEO-c
experiment are used to perform a first measurement of , the
fractional -even content of the self-conjugate decay , obtaining a value of . An important
input to the measurement comes from the use of
and decays to tag the signal mode. This same
technique is applied to the channels and , yielding and
, where the first uncertainty is
statistical and the second systematic. These measurements are consistent with
those of an earlier analysis, based on -eigenstate tags, and can be
combined to give values of and
. The results will enable the three modes to
be included in a model-independent manner in measurements of the unitarity
triangle angle using decays, and in time-dependent
studies of violation and mixing in the system.Comment: Minor revisions following journal acceptanc
First observation of Bs0 â D*s2+XÎŒ-Îœ decays
Using data collected with the LHCb detector in protonâproton collisions at a centre-of-mass energy of 7 TeV, the semileptonic decays B0sâD+sXÎŒâÎœ and B0sâD0K+XÎŒâÎœ are detected. Two structures are observed in the D0K+ mass spectrum at masses consistent with the known Ds1(2536)+ and Dâs22573)+ mesons. The measured branching fractions relative to the total B0s semileptonic rate are B(B0sâDâ+s2XÎŒâÎœ)/B(B0sâXÎŒâÎœ) = (3.3±1.0±0.4)%, and B(B0sâD+s1XÎŒâÎœ)/B(B0sâXÎŒâÎœ) = (5.4±1.2±0.5)%, where the ïŹrst uncertainty is statistical and the second is systematic. This is the ïŹrst observation of the Dâ+s2 state in B0s decays; we also measure its mass and width
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
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