Study of the production of Λ_b^0 band ~0 hadrons in pp collisions and first measurement of the Λ_b^0→J/ψpK^- branching fraction

The product of the ∧0/b （-B/0） differential production cross-section and the branching fraction of the decay ∧0/b→ J/ψ pK-（-B/0→ J/ψ-K＊（892）0）is measured as a function of the beauty hadron transverse momentum, PT, and rapidity, y. The kinematic region of the measurements is pT〈20 GeV/c and 2.0 〈g〈4.5.The measurements use a data sample corresponding to an integrated luminosity of 3fb-1 collected by the LHCb detector in pp collisions at centre-of-mass energies √s=7 TeV in 2011 and √s=8 TeV in 2012. Based on previous LHCb results of the fragmentation fraction ratio,f∧0/b/fd,the branching fraction of the decay ∧0/b→ J/ψ pK-is measured to be B（∧0/b→ J/ψ pK-）=（3.17±0.04±0.07±0.34＋0.45/-0.28）×10-4,where the first uncertainty is statistical, the second is systematic, the third is due to the uncertainty on the branching fraction of the decay -B/0 →J/ψ-K＊（892）0,and the fourth is due to the knowledge of f∧0/b/fd.The sum of the asymmetries in the production and decay between ∧0/b and ∧0/bis also measured as a function of PT and y.The previously published branching fraction of ∧0/b→ J/ψ pπ-,relative to that of ∧0/b→ J/ψ pK-,is updated. The branching fractions of ∧0/b→P＋c（→ J/ψp）K-are determined.

Measurement of the integrated luminosity of the Phase 2 data of the Belle Ⅱ experiment

From April to July 2018,a data sample at the peak energy of the T(4 S) resonance was collected with the Belle Ⅱ detector at the SuperKEKB electron-positron collider.This is the first data sample of the Belle Ⅱ experiment.Using Bhabha and digamma events,we measure the integrated luminosity of the data sample to be(496.3±0.3±3.0) pb-1,where the first uncertainty is statistical and the second is systematic.This work provides a basis for future luminosity measurements at Belle Ⅱ.

Enhancement of photocatalytic and photoelectrochemical properties of TiO_(2) nanotubes sensitized by SILAR-Deposited PbS nanoparticles

The aim of this work is to improve the photocatalytic and photoelectrochemical properties of TiO_(2) nanotubes(TiO_(2)-NTAs)by sensitizing them with PbS nanoparticles(NPs)prepared by the Successive Ionic Layer Adsorption and Reaction method(SILAR).The Microstructure,surface morphology,phase composition and optical properties of the prepared structure were characterized using X-ray diffraction(XRD),scanning electron microscopy(SEM),transmission electron microscopy(TEM and High-resolution mode HRTEM)and X-ray photoelectron spectroscopy(XPS).The TiO_(2) NTAs were loaded by PbS NPs,which contents increase by increasing the number of SILAR cycles.The PbS NPs,which have a size in the order of ~20 nm,were found to be uniformly distributed in the TiO_(2) NTAs without damaging the tubular ordered structure.The photocatalytic activity of the PbS/TiO_(2) NTAs system,toward Amido Black(AB),showed significant enhancement compared to the bare untreated TiO_(2) NTs.At 30 SILAR deposition cycles the PbS-NPs/TiO_(2) NTAs structure is able to remove 75% of BA under simulated solar light,considerably higher than the 40% removal obtained with unloaded TiO_(2) NTAs.A significant improvement of the Photoelectrochemical(PEC)efficiency has been also demonstrated for the PbS-NPs/TiO_(2) NTAs hybrid system.This improvement is mainly related to visible-light harvesting and reduced recombination of photo-generated electron-hole pairs due to the synergistic effect of the heterojunction and to the wellorganized morphology of the TiO_(2) NTAs.