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At least 721 records · Page 40
All sourcesNASA NTRSDOE OSTI
DOE OSTI2024

Determination of short- and long-distance contributions in B 0 → K * 0 μ + μ − decays

An amplitude analysis of the B 0 → K * 0 μ + μ − decay is presented. The analysis is based on data collected by the LHCb experiment from proton-proton collisions at s = 7 , 8 and 13 TeV, corresponding to an integrated luminosity of 4.7 fb − 1 . For the first time, Wilson coefficients and nonlocal hadronic contributions are accessed directly from the unbinned data, where the latter are parametrized as a function of q 2 with a polynomial expansion. Wilson coefficients and nonlocal hadronic parameters are determined under two alternative hypotheses: the first relies on experimental information alone, while the second one includes information from theoretical predictions for the nonlocal contributions. Both models obtain similar results for the parameters of interest. The overall level of compatibility with the Standard Model is evaluated to be between 1.8 and 1.9 standard deviations when looking at the C 9 Wilson coefficient alone, and between 1.3 and 1.4 standard deviations when considering the full set of C 9 , C 10 , C 9 ′ and C 10 ′ Wilson coefficients. The ranges reflect the theoretical assumptions made in the analysis. © 2024 CERN, for the LHCb Collaboration 2024 CERN

Aaij, R. (ORCID:0000000305331952)↗
DOE OSTI2023

Observation of a Resonant Structure near the D s + D s - Threshold in the B + → D s + D s - K + Decay

An amplitude analysis of the B + → $D^{+}_{s}$ $D^{-}_{s}$ ⁢K + decay is carried out to study for the first time its intermediate resonant contributions, using proton-proton collision data collected with the LHCb detector at center-of-mass energies of 7, 8, and 13 TeV. A near-threshold peaking structure, referred to as X⁡(3960), is observed in the $D^{+}_{s}$ $D^{-}_{s}$ invariant-mass spectrum with significance greater than 12 standard deviations. The mass, width, and the quantum numbers of the structure are measured to be 3956 ± 5 ± 10 MeV, 43 ± 13 ± 8 MeV, and J P⁢C = 0 ++ , respectively, where the first uncertainties are statistical and the second systematic. The properties of the new structure are consistent with recent theoretical predictions for a state composed of c$\overline{c}$s$\overline{s}$ quarks. Evidence for an additional structure is found around 4140 MeV in the $D^{+}_{s}$ $D^{-}_{s}$ invariant mass, which might be caused either by a new resonance with the 0 ++ assignment or by a J/ψ⁢Φ ↔ $D^{+}_{s}$ $D^{-}_{s}$ coupled-channel effect.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2023

Observation of New Ω c 0 States Decaying to the Ξ c + K - Final State

Two new excited states, Ω c (3185) 0 and Ω c ⁢(3327) 0 , are observed in the $Ξ^{+}_{c}$K - invariant-mass spectrum using proton-proton collision data collected by the LHCb experiment, corresponding to an integrated luminosity of 9 fb -1 . Five previously observed excited $Ω^{0}_{c}$ states are confirmed, namely Ω c ⁢(3000) 0 , Ω c ⁢(3050) 0 , Ω c⁢ (3065) 0 , Ω c⁢ (3090) 0 , and Ω c⁢ (3119) 0 . The masses and widths of these seven states are measured with the highest precision to date.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2024

Superfluorescence from Electron-Hole Plasma at Moderate Temperatures of 175 K

Superfluorescence, a cooperative coherent spontaneous emission, is of great importance to the understanding of many-body correlation in optical processes. Even though superfluorescence has been demonstrated in many diverse systems, it is hard to observe in electron-hole plasma (EHP) due to its rapid dephasing and hence needs strong magnetic fields or complex microcavities. Herein, we report the first experimental observation of superfluorescence from EHP up to a moderate temperature of 175 K without external stimuli in a coupled metal halide perovskite quantum dots film. The EHP exhibits macroscopic quantum coherence through spontaneous synchronization. The coherence of the excited state decays by superfluorescence, which is redshifted 40 meV from the spontaneous emission with a ~1700 times faster decay rate and exhibits quadratic fluence dependence. Notably, the excited state population's delayed growth and abrupt decay, which are strongly influenced by the pump fluence and the Burnham-Chiao ringing, are the characteristics of the superfluorescence. Our findings will open up a new frontier for cooperative emission and light beam-based technologies.

CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS↗
DOE OSTI2024

Amplitude Analysis of the B 0 → K * 0 μ + μ − Decay

An amplitude analysis of the B 0 → K * 0 μ + μ − decay is presented using a dataset corresponding to an integrated luminosity of 4.7 fb − 1 of p p collision data collected with the LHCb experiment. For the first time, the coefficients associated to short-distance physics effects, sensitive to processes beyond the standard model, are extracted directly from the data through a q 2 -unbinned amplitude analysis, where q 2 is the μ + μ − invariant mass squared. Long-distance contributions, which originate from nonfactorizable QCD processes, are systematically investigated, and the most accurate assessment to date of their impact on the physical observables is obtained. The pattern of measured corrections to the short-distance couplings is found to be consistent with previous analyses of b - to s -quark transitions, with the largest discrepancy from the standard model predictions found to be at the level of 1.8 standard deviations. The global significance of the observed differences in the decay is 1.4 standard deviations. © 2024 CERN, for the LHCb Collaboration 2024 CERN

Aaij, R. (ORCID:0000000305331952)↗
DOE OSTI2021

Ground electronic state description of thiourea coordination in homoleptic Zn 2+ , Ni 2+ and Co 2+ complexes using sulfur K -edge X-ray absorption spectroscopy

Sulfur K-edge X-ray absorption spectroscopy (XAS) was employed to experimentally characterize the coordinative bond between the thiourea (TU) or thiocarbamide ligand and transition metal (TM) ions Zn 2+ , Co 2+ and Ni 2+ in distorted tetrahedral and octahedral homoleptic coordination environments. Comparisons of XAS spectra of the free TU ligand and [Zn(TU) 4 ] 2+ , [Co(TU) 4 ] 2+ and [Ni(TU) 6 ] 2+ complexes clearly identify spectral features unique to TM 2+ –S(TU) bonding. Quantitative analysis of pre-edge intensities describes the covalency of Ni 2+ —S(TU) and Co 2+ —S(TU) bonding to be at most 21% and 9% as expressed by the S 3p contributions per TM 3d electron hole. Using relevant Ni 2+ complexes with dithiocarbamate and thioether ligands, we evaluated the empirical S 1s → 3p transition dipole integrals developed for S-donor ligands and their dependence on heteroatom substitutions. With the aid of density functional theory-based ground electronic state calculations, we found evidence for the need of using a transition dipole that is dependent on the presence of conjugated heteroatom (N) substitution in these S-donor ligands.

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEA↗
DOE OSTI2020

Multiplicity dependence of $\pi$, K, and p production in pp collisions at $\sqrt{s}$ = 13 TeV

This paper presents the measurements of π ± , K ± , p and $\bar{p}$ transverse momentum (p T ) spectra as a function of charged-particle multiplicity density in proton–proton (pp) collisions at $\sqrt{s}$ = 13TeV with the ALICE detector at the LHC. Such study allows us to isolate the center-of-mass energy dependence of light-flavour particle production. The measurements reported here cover a p T range from 0.1 to 20 GeV / c and are done in the rapidity interval | y| < 0.5. The p T -differential particle ratios exhibit an evolution with multiplicity, similar to that observed in pp collisions at $\sqrt{s}$ = 7 TeV, which is qualitatively described by some of the hydrodynamical and pQCD-inspired models discussed in this paper. Furthermore, the p T -integrated hadron-to-pion yield ratios measured in pp collisions at two different center-of-mass energies are consistent when compared at similar multiplicities. This also extends to strange and multi-strange hadrons, suggesting that, at LHC energies, particle hadrochemistry scales with particle multiplicity the same way under different collision energies and colliding systems.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2020

Materials Data on K(BH)3 by Materials Project

K(BH)3 is Parent of FeAs superconductors-derived structured and crystallizes in the cubic Fm-3m space group. The structure is zero-dimensional and consists of twenty-four boranediylradical molecules and eight potassium molecules.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on K(CoSe)2 by Materials Project

KCo2Se2 is alpha bismuth trifluoride-derived structured and crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. K1+ is bonded in a body-centered cubic geometry to eight equivalent Se2- atoms. All K–Se bond lengths are 3.41 Å. Co+1.50+ is bonded to four equivalent Se2- atoms to form a mixture of edge and corner-sharing CoSe4 tetrahedra. All Co–Se bond lengths are 2.35 Å. Se2- is bonded in a 8-coordinate geometry to four equivalent K1+ and four equivalent Co+1.50+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on K(OsO3)2 by Materials Project

KOs2O6 crystallizes in the cubic Fd-3m space group. The structure is three-dimensional. K1+ is bonded to six equivalent O2- atoms to form KO6 octahedra that share corners with twelve equivalent OsO6 octahedra. The corner-sharing octahedral tilt angles are 70°. All K–O bond lengths are 3.16 Å. Os+5.50+ is bonded to six equivalent O2- atoms to form OsO6 octahedra that share corners with six equivalent KO6 octahedra and corners with six equivalent OsO6 octahedra. The corner-sharing octahedra tilt angles range from 41–70°. All Os–O bond lengths are 1.93 Å. O2- is bonded in a distorted bent 150 degrees geometry to one K1+ and two equivalent Os+5.50+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on K(OsO3)2 by Materials Project

KOs2O6 crystallizes in the triclinic P-1 space group. The structure is three-dimensional. K1+ is bonded in a 11-coordinate geometry to eleven O2- atoms. There are a spread of K–O bond distances ranging from 2.73–3.21 Å. There are two inequivalent Os+5.50+ sites. In the first Os+5.50+ site, Os+5.50+ is bonded to six O2- atoms to form a mixture of edge and corner-sharing OsO6 octahedra. The corner-sharing octahedra tilt angles range from 38–45°. There are a spread of Os–O bond distances ranging from 1.93–1.99 Å. In the second Os+5.50+ site, Os+5.50+ is bonded to six O2- atoms to form a mixture of edge and corner-sharing OsO6 octahedra. The corner-sharing octahedra tilt angles range from 38–45°. There are a spread of Os–O bond distances ranging from 1.89–1.96 Å. There are six inequivalent O2- sites. In the first O2- site, O2- is bonded in a 2-coordinate geometry to two equivalent K1+ and two equivalent Os+5.50+ atoms. In the second O2- site, O2- is bonded in a 3-coordinate geometry to one K1+ and two Os+5.50+ atoms. In the third O2- site, O2- is bonded in a 2-coordinate geometry to three equivalent K1+ and two Os+5.50+ atoms. In the fourth O2- site, O2- is bonded in a 2-coordinate geometry to two equivalent K1+ and two equivalent Os+5.50+ atoms. In the fifth O2- site, O2- is bonded in a 2-coordinate geometry to two equivalent K1+ and two Os+5.50+ atoms. In the sixth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one K1+ and two Os+5.50+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on K(NiS)2 by Materials Project

KNi2S2 is alpha bismuth trifluoride-derived structured and crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. K1+ is bonded in a body-centered cubic geometry to eight equivalent S2- atoms. All K–S bond lengths are 3.31 Å. Ni+1.50+ is bonded to four equivalent S2- atoms to form a mixture of edge and corner-sharing NiS4 tetrahedra. All Ni–S bond lengths are 2.26 Å. S2- is bonded in a 4-coordinate geometry to four equivalent K1+ and four equivalent Ni+1.50+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on K(RuO2)4 by Materials Project

KRu4O8 crystallizes in the tetragonal I4/m space group. The structure is three-dimensional. K1+ is bonded in a body-centered cubic geometry to eight equivalent O2- atoms. All K–O bond lengths are 2.96 Å. Ru+3.75+ is bonded to six O2- atoms to form a mixture of edge and corner-sharing RuO6 octahedra. The corner-sharing octahedral tilt angles are 53°. There are a spread of Ru–O bond distances ranging from 1.95–2.07 Å. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a trigonal planar geometry to three equivalent Ru+3.75+ atoms. In the second O2- site, O2- is bonded in a 5-coordinate geometry to two equivalent K1+ and three equivalent Ru+3.75+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on K(NiSe)2 by Materials Project

KNi2Se2 is alpha bismuth trifluoride-derived structured and crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. K1+ is bonded in a body-centered cubic geometry to eight equivalent Se2- atoms. All K–Se bond lengths are 3.40 Å. Ni+1.50+ is bonded to four equivalent Se2- atoms to form a mixture of edge and corner-sharing NiSe4 tetrahedra. All Ni–Se bond lengths are 2.39 Å. Se2- is bonded in a 8-coordinate geometry to four equivalent K1+ and four equivalent Ni+1.50+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on K(FeSb3)4 by Materials Project

KFe4Sb12 crystallizes in the cubic Im-3 space group. The structure is three-dimensional. K1+ is bonded to twelve equivalent Sb1- atoms to form KSb12 cuboctahedra that share faces with eight equivalent FeSb6 octahedra. All K–Sb bond lengths are 3.45 Å. Fe+2.75+ is bonded to six equivalent Sb1- atoms to form FeSb6 octahedra that share corners with six equivalent FeSb6 octahedra and faces with two equivalent KSb12 cuboctahedra. The corner-sharing octahedral tilt angles are 53°. All Fe–Sb bond lengths are 2.58 Å. Sb1- is bonded in a 2-coordinate geometry to one K1+, two equivalent Fe+2.75+, and two equivalent Sb1- atoms. There are one shorter (2.99 Å) and one longer (3.02 Å) Sb–Sb bond lengths.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on K(GeAs)3 by Materials Project

KGe3As3 crystallizes in the orthorhombic Pnma space group. The structure is three-dimensional. K1+ is bonded in a 6-coordinate geometry to six As3- atoms. There are a spread of K–As bond distances ranging from 3.34–3.74 Å. There are three inequivalent Ge+2.67+ sites. In the first Ge+2.67+ site, Ge+2.67+ is bonded to four As3- atoms to form corner-sharing GeAs4 tetrahedra. There are a spread of Ge–As bond distances ranging from 2.45–2.50 Å. In the second Ge+2.67+ site, Ge+2.67+ is bonded in a distorted trigonal non-coplanar geometry to three As3- atoms. All Ge–As bond lengths are 2.52 Å. In the third Ge+2.67+ site, Ge+2.67+ is bonded in a water-like geometry to two equivalent As3- atoms. Both Ge–As bond lengths are 2.57 Å. There are three inequivalent As3- sites. In the first As3- site, As3- is bonded to three equivalent K1+ and three Ge+2.67+ atoms to form distorted AsK3Ge3 octahedra that share corners with two equivalent AsK2Ge3 square pyramids, edges with four equivalent AsK3Ge3 octahedra, and edges with three equivalent AsK2Ge3 square pyramids. In the second As3- site, As3- is bonded to two equivalent K1+ and three Ge+2.67+ atoms to form distorted AsK2Ge3 square pyramids that share corners with two equivalent AsK3Ge3 octahedra, edges with three equivalent AsK3Ge3 octahedra, and edges with two equivalent AsK2Ge3 square pyramids. The corner-sharing octahedral tilt angles are 19°. In the third As3- site, As3- is bonded in a rectangular see-saw-like geometry to one K1+ and three Ge+2.67+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Characterizing Polyoxovanadate‐Alkoxide Clusters Using Vanadium K‐Edge X‐Ray Absorption Spectroscopy

Abstract A number of technologies would benefit from developing inorganic compounds and materials with specific electronic and magnetic exchange properties. Unfortunately, designing compounds with these properties is difficult because metal⋅⋅⋅metal coupling schemes are hard to predict and control. Fully characterizing communication between metals in existing compounds that exhibit interesting properties could provide valuable insight and advance those predictive capabilities. One such class of molecules are the series of Lindqvist iron‐functionalized and hexavanadium polyoxovanadate‐alkoxide clusters, which we characterized here using V K‐edge X‐ray absorption spectroscopy. Substantial changes in the pre‐edge peak intensities were observed that tracked with the V 3 d ‐electron count. The data also suggested substantial delocalization between the vanadium cations. Meanwhile, the Fe III cations were electronically isolated from the polyoxovanadate core.

Meyer, Rachel L.↗
DOE OSTI2022

A measurement of the K + → π + μ + μ – decay

A sample of 2.8 × 10 4 K + → π + μ + μ – candidates with negligible background was collected by the NA62 experiment at the CERN SPS in 2017–2018. The model-independent branching fraction is measured to be (9.15 ± 0.08) × 10 –8 , a factor three more precise than previous measurements. The decay form factor is presented as a function of the squared dimuon mass. A measurement of the form factor parameters and their uncertainties is performed using a description based on Chiral Perturbation Theory at O(p 6 ).

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗