332 research outputs found
Study of the decay
The decay is studied
in proton-proton collisions at a center-of-mass energy of TeV
using data corresponding to an integrated luminosity of 5
collected by the LHCb experiment. In the system, the
state observed at the BaBar and Belle experiments is
resolved into two narrower states, and ,
whose masses and widths are measured to be where the first uncertainties are statistical and the second
systematic. The results are consistent with a previous LHCb measurement using a
prompt sample. Evidence of a new
state is found with a local significance of , whose mass and width
are measured to be and , respectively. In addition, evidence of a new decay mode
is found with a significance of
. The relative branching fraction of with respect to the
decay is measured to be , where the first
uncertainty is statistical, the second systematic and the third originates from
the branching fractions of charm hadron decays.Comment: All figures and tables, along with any supplementary material and
additional information, are available at
https://cern.ch/lhcbproject/Publications/p/LHCb-PAPER-2022-028.html (LHCb
public pages
Consensus guidelines for the use and interpretation of angiogenesis assays
The formation of new blood vessels, or angiogenesis, is a complex process that plays important roles in growth and development, tissue and organ regeneration, as well as numerous pathological conditions. Angiogenesis undergoes multiple discrete steps that can be individually evaluated and quantified by a large number of bioassays. These independent assessments hold advantages but also have limitations. This article describes in vivo, ex vivo, and in vitro bioassays that are available for the evaluation of angiogenesis and highlights critical aspects that are relevant for their execution and proper interpretation. As such, this collaborative work is the first edition of consensus guidelines on angiogenesis bioassays to serve for current and future reference
Measurement of the ratios of branching fractions and
The ratios of branching fractions
and are measured, assuming isospin symmetry, using a
sample of proton-proton collision data corresponding to 3.0 fb of
integrated luminosity recorded by the LHCb experiment during 2011 and 2012. The
tau lepton is identified in the decay mode
. The measured values are
and
, where the first uncertainty is
statistical and the second is systematic. The correlation between these
measurements is . Results are consistent with the current average
of these quantities and are at a combined 1.9 standard deviations from the
predictions based on lepton flavor universality in the Standard Model.Comment: All figures and tables, along with any supplementary material and
additional information, are available at
https://cern.ch/lhcbproject/Publications/p/LHCb-PAPER-2022-039.html (LHCb
public pages
Conceptual Design Report: Scientific Instrument Single Particles, Clusters, and Biomolecules (SPB)
VII. Time-resolved diffraction imaging
The excellent transverse coherence of XFEL radiation allows high-resolution imaging to be performed without lenses. The short-duration XFEL pulses also permit time-resolved measurements using pump-probe techniques. Of particular interest is the study of irreversible dynamic processes, which is made possible by the extreme pulse energy of XFELs
Design of the mirror optical systems for coherent diffractive imaging at the SPB/SFX instrument of the European XFEL
The high degree of spatial coherence and extreme pulse energies available at x-ray free electron laser (XFEL) sources naturally support coherent diffractive imaging applications. In order to optimally exploit these unique properties, the optical systems at XFELs must be highly transmissive, focus to appropriate sizes matched to the scale of samples to be investigated and must minimally perturb the wavefront of the XFEL beam. We present the design and simulated performance of two state-of-the-art KirkpatrikâBaez mirror systems that form the primary foci of the single particles, clusters and biomolecules and serial femtosecond crystallography (SPB/SFX) instrument of the European XFEL. The two systems, presently under construction, will produce 1 ÎŒm and 100 nm scale foci across a 3â16 keV photon energy range. Targeted applications include coherent imaging of weakly scattering, often biological, specimens
Coherent Diffractive Imaging of Biological Samples at Synchrotron and Free Electron Laser Facilities
Coherent X-ray diffractive imaging (CXDI) is a new imaging technique that offers the potential to image non-crystalline materials to sub-nanometer resolutions. Here we review the progress in CXDI of biological samples at both synchrotron and free electron laser (FEL) sources. We outline the experimental design of a CXDI experiment and summarize the iterative phase retrieval techniques that are used to produce images from the measured diffraction patterns. We describe a selection of key experiments performed in bio-imaging with CXDI from synchrotron sources, and we discuss the proof-of-principle experiments performed at FLASH at DESY in Hamburg. Finally, we show through simulation that for realistic parameters of hard X-ray FELs a resolution of a few nanometers may be achieved for individual biological objects imaged with single pulses of FEL radiation. Furthermore, we revise how this resolution may be improved to the sub-nanometer range if we image multiple copies of samples with a reproducible structure
Tracking of non-repetitive processes with full field hard X-ray MHz rate single bunch imaging
We report on the successful observation of shockwave propagation in liquid media induced by the focused optical laser. Shockwave was generated by absorption of laser power in water mixed with Nile blue dye. The whole process was imaged by full-field propagation based hard X-ray imaging technique at MHz single bunch mode in ESRF ID19 beamline. We found the optimal parameters such as the laser power density shape of the water-air interface and concentration of dye, under which the fairly repeatable generation of the liquid jet has been achieved. The observed speed of jet was in excess of 126m/s, which makes such jet an interesting candidate for the sample delivery at European XFEL. Moreover, with the fine time tuning of the pump laser in the sheet capillary, we observed the evidence of the shockwave propagating at the speed ~1.5km/s. This work opens up possibilities for full field MHz imaging of non-repetitive processes at European XFEL, where due to better signal to noise ratio the quantitative imaging can be performed in micron- to nano-scale spatial resolution while simultaneously reaching time resolutions down to fs regio
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