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At least 451 records · Page 25
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Strong constraints on the b → sγ photon polarisation from B0 → K*0e+e-decays

An angular analysis of the B 0 → K* 0 e + e - decay is performed using a data sample corresponding to an integrated luminosity of 9 fb - 1 of pp collisions collected with the LHCb experiment. The analysis is conducted in the very low dielectron mass squared ( q 2 ) interval between 0 . 0008 and 0 . 257 GeV 2 , where the rate is dominated by the B 0 → K * 0 γ transition with a virtual photon. The fraction of longitudinal polarisation of the K * 0 meson, F L , is measured to be F L = (4 . 4 ± 2 . 6 ± 1 . 4)%, where the first uncertainty is statistical and the second systematic. The \( {A}_{\mathrm{T}}^{\mathrm{Re}} \) observable, which is related to the lepton forward-backward asymmetry, is measured to be \( {A}_{\mathrm{T}}^{\mathrm{Re}} \) = - 0 . 06 ± 0 . 08 ± 0 . 02. The \( {A}_{\mathrm{T}}^{(2)} \) and \( {A}_{\mathrm{T}}^{\mathrm{Im}} \) transverse asymmetries, which are sensitive to the virtual photon polarisation, are found to be \( {A}_{\mathrm{T}}^{(2)} \) = 0 . 11 ± 0 . 10 ± 0 . 02 and \( {A}_{\mathrm{T}}^{\mathrm{Im}} \) = 0 . 02 ± 0 . 10 ± 0 . 01. The results are consistent with Standard Model predictions and provide the world’s best constraint on the b → sγ photon polarisation.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2020

Materials Data on K(V5S8)2 by Materials Project

K(V5S8)2 is Orthorhombic Perovskite-like structured and crystallizes in the monoclinic P2 space group. The structure is three-dimensional. there are two inequivalent K1+ sites. In the first K1+ site, K1+ is bonded in a distorted q6 geometry to ten S2- atoms. There are a spread of K–S bond distances ranging from 3.16–3.32 Å. In the second K1+ site, K1+ is bonded in a distorted q6 geometry to ten S2- atoms. There are a spread of K–S bond distances ranging from 3.16–3.32 Å. There are twelve inequivalent V+3.10+ sites. In the first V+3.10+ site, V+3.10+ is bonded to six S2- atoms to form a mixture of corner, edge, and face-sharing VS6 octahedra. The corner-sharing octahedra tilt angles range from 49–55°. There are a spread of V–S bond distances ranging from 2.27–2.54 Å. In the second V+3.10+ site, V+3.10+ is bonded to six S2- atoms to form a mixture of corner, edge, and face-sharing VS6 octahedra. The corner-sharing octahedra tilt angles range from 44–54°. There are a spread of V–S bond distances ranging from 2.27–2.51 Å. In the third V+3.10+ site, V+3.10+ is bonded to six S2- atoms to form a mixture of corner, edge, and face-sharing VS6 octahedra. The corner-sharing octahedra tilt angles range from 49–55°. There are a spread of V–S bond distances ranging from 2.27–2.53 Å. In the fourth V+3.10+ site, V+3.10+ is bonded to six S2- atoms to form a mixture of corner, edge, and face-sharing VS6 octahedra. The corner-sharing octahedra tilt angles range from 44–54°. There are a spread of V–S bond distances ranging from 2.27–2.51 Å. In the fifth V+3.10+ site, V+3.10+ is bonded to six S2- atoms to form a mixture of corner, edge, and face-sharing VS6 octahedra. The corner-sharing octahedra tilt angles range from 49–54°. There are a spread of V–S bond distances ranging from 2.25–2.61 Å. In the sixth V+3.10+ site, V+3.10+ is bonded to six S2- atoms to form a mixture of corner, edge, and face-sharing VS6 octahedra. The corner-sharing octahedra tilt angles range from 49–55°. There are a spread of V–S bond distances ranging from 2.27–2.61 Å. In the seventh V+3.10+ site, V+3.10+ is bonded to six S2- atoms to form a mixture of corner, edge, and face-sharing VS6 octahedra. The corner-sharing octahedra tilt angles range from 49–54°. There are a spread of V–S bond distances ranging from 2.25–2.61 Å. In the eighth V+3.10+ site, V+3.10+ is bonded to six S2- atoms to form a mixture of corner, edge, and face-sharing VS6 octahedra. The corner-sharing octahedra tilt angles range from 49–55°. There are a spread of V–S bond distances ranging from 2.27–2.61 Å. In the ninth V+3.10+ site, V+3.10+ is bonded to six S2- atoms to form a mixture of corner and edge-sharing VS6 octahedra. The corner-sharing octahedra tilt angles range from 44–50°. There are a spread of V–S bond distances ranging from 2.31–2.45 Å. In the tenth V+3.10+ site, V+3.10+ is bonded to six S2- atoms to form a mixture of corner and edge-sharing VS6 octahedra. The corner-sharing octahedra tilt angles range from 44–50°. There are a spread of V–S bond distances ranging from 2.31–2.45 Å. In the eleventh V+3.10+ site, V+3.10+ is bonded to six S2- atoms to form a mixture of corner and edge-sharing VS6 octahedra. The corner-sharing octahedra tilt angles range from 44–50°. There are a spread of V–S bond distances ranging from 2.31–2.46 Å. In the twelfth V+3.10+ site, V+3.10+ is bonded to six S2- atoms to form a mixture of corner and edge-sharing VS6 octahedra. The corner-sharing octahedra tilt angles range from 44–50°. There are a spread of V–S bond distances ranging from 2.31–2.45 Å. There are sixteen inequivalent S2- sites. In the first S2- site, S2- is bonded in a 4-coordinate geometry to one K1+ and four V+3.10+ atoms. In the second S2- site, S2- is bonded to four V+3.10+ atoms to form distorted edge-sharing SV4 trigonal pyramids. In the third S2- site, S2- is bonded in a 4-coordinate geometry to one K1+ and three V+3.10+ atoms. In the fourth S2- site, S2- is bonded in a 4-coordinate geometry to one K1+ and three V+3.10+ atoms. In the fifth S2- site, S2- is bonded in a 4-coordinate geometry to one K1+ and three V+3.10+ atoms. In the sixth S2- site, S2- is bonded in a 4-coordinate geometry to one K1+ and three V+3.10+ atoms. In the seventh S2- site, S2- is bonded in a 5-coordinate geometry to five V+3.10+ atoms. In the eighth S2- site, S2- is bonded in a 5-coordinate geometry to five V+3.10+ atoms. In the ninth S2- site, S2- is bonded in a 5-coordinate geometry to five V+3.10+ atoms. In the tenth S2- site, S2- is bonded in a 5-coordinate geometry to five V+3.10+ atoms. In the eleventh S2- site, S2- is bonded in a 4-coordinate geometry to one K1+ and three V+3.10+ atoms. In the twelfth S2- site, S2- is bonded in a 4-coordinate geometry to one K1+ and three V+3.10+ atoms. In the thirteenth S2- site, S2- is bonded in a 4-coordinate geometry to one K1+ and three V+3.10+ atoms. In the fourteenth S2- site, S2- is bonded in a 4-coordinate geometry to one K1+ and three V+3.10+ atoms. In the fifteenth S2- site, S2- is bonded in a 4-coordinate geometry to one K1+ and four V+3.10+ atoms. In the sixteenth S2- site, S2- is bonded to four V+3.10+ atoms to form distorted edge-sharing SV4 trigonal pyramids.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on K(SnAu2)2 by Materials Project

KAu4Sn2 crystallizes in the tetragonal I-4c2 space group. The structure is three-dimensional. K is bonded in a 8-coordinate geometry to eight equivalent Au atoms. There are four shorter (3.46 Å) and four longer (3.57 Å) K–Au bond lengths. Au is bonded in a 10-coordinate geometry to two equivalent K, four equivalent Au, and four equivalent Sn atoms. There are a spread of Au–Au bond distances ranging from 2.80–3.08 Å. There are a spread of Au–Sn bond distances ranging from 2.82–3.04 Å. Sn is bonded in a 8-coordinate geometry to eight equivalent Au atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on K(MoO2)4 by Materials Project

K(MoO2)4 crystallizes in the monoclinic P2/c space group. The structure is three-dimensional. there are two inequivalent K1+ sites. In the first K1+ site, K1+ is bonded in a body-centered cubic geometry to eight O2- atoms. There are a spread of K–O bond distances ranging from 3.08–3.25 Å. In the second K1+ site, K1+ is bonded in a distorted body-centered cubic geometry to eight O2- atoms. There are a spread of K–O bond distances ranging from 3.03–3.27 Å. There are four inequivalent Mo+3.75+ sites. In the first Mo+3.75+ site, Mo+3.75+ is bonded to six O2- atoms to form a mixture of corner and edge-sharing MoO6 octahedra. The corner-sharing octahedra tilt angles range from 50–56°. There are a spread of Mo–O bond distances ranging from 2.12–2.18 Å. In the second Mo+3.75+ site, Mo+3.75+ is bonded to six O2- atoms to form a mixture of corner and edge-sharing MoO6 octahedra. The corner-sharing octahedra tilt angles range from 46–53°. There are a spread of Mo–O bond distances ranging from 2.03–2.17 Å. In the third Mo+3.75+ site, Mo+3.75+ is bonded to six O2- atoms to form a mixture of corner and edge-sharing MoO6 octahedra. The corner-sharing octahedra tilt angles range from 46–56°. There are a spread of Mo–O bond distances ranging from 1.99–2.16 Å. In the fourth Mo+3.75+ site, Mo+3.75+ is bonded to six O2- atoms to form a mixture of corner and edge-sharing MoO6 octahedra. The corner-sharing octahedra tilt angles range from 50–55°. There are a spread of Mo–O bond distances ranging from 1.97–2.16 Å. There are eight inequivalent O2- sites. In the first O2- site, O2- is bonded in a 5-coordinate geometry to two K1+ and three Mo+3.75+ atoms. In the second O2- site, O2- is bonded in a trigonal planar geometry to three Mo+3.75+ atoms. In the third O2- site, O2- is bonded in a 3-coordinate geometry to two K1+ and three Mo+3.75+ atoms. In the fourth O2- site, O2- is bonded in a 3-coordinate geometry to two K1+ and three Mo+3.75+ atoms. In the fifth O2- site, O2- is bonded in a distorted trigonal planar geometry to three Mo+3.75+ atoms. In the sixth O2- site, O2- is bonded in a distorted trigonal planar geometry to three Mo+3.75+ atoms. In the seventh O2- site, O2- is bonded in a distorted trigonal planar geometry to three Mo+3.75+ atoms. In the eighth O2- site, O2- is bonded in a 5-coordinate geometry to two K1+ and three Mo+3.75+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on K(GeSe2)2 by Materials Project

K(GeSe2)2 crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional. there are two inequivalent K1+ sites. In the first K1+ site, K1+ is bonded in a 7-coordinate geometry to seven Se2- atoms. There are a spread of K–Se bond distances ranging from 3.38–3.95 Å. In the second K1+ site, K1+ is bonded in a 7-coordinate geometry to seven Se2- atoms. There are a spread of K–Se bond distances ranging from 3.37–3.98 Å. There are four inequivalent Ge+3.50+ sites. In the first Ge+3.50+ site, Ge+3.50+ is bonded to four Se2- atoms to form a mixture of corner and edge-sharing GeSe4 tetrahedra. There are a spread of Ge–Se bond distances ranging from 2.38–2.47 Å. In the second Ge+3.50+ site, Ge+3.50+ is bonded to four Se2- atoms to form corner-sharing GeSe4 tetrahedra. There are a spread of Ge–Se bond distances ranging from 2.35–2.47 Å. In the third Ge+3.50+ site, Ge+3.50+ is bonded to four Se2- atoms to form a mixture of corner and edge-sharing GeSe4 tetrahedra. There are a spread of Ge–Se bond distances ranging from 2.40–2.46 Å. In the fourth Ge+3.50+ site, Ge+3.50+ is bonded to four Se2- atoms to form corner-sharing GeSe4 tetrahedra. There are two shorter (2.63 Å) and two longer (2.64 Å) Ge–Se bond lengths. There are eight inequivalent Se2- sites. In the first Se2- site, Se2- is bonded in a 2-coordinate geometry to one K1+ and two Ge+3.50+ atoms. In the second Se2- site, Se2- is bonded in a 2-coordinate geometry to two K1+ and two Ge+3.50+ atoms. In the third Se2- site, Se2- is bonded in a 4-coordinate geometry to two K1+ and two Ge+3.50+ atoms. In the fourth Se2- site, Se2- is bonded in a 3-coordinate geometry to three K1+ and two Ge+3.50+ atoms. In the fifth Se2- site, Se2- is bonded in a distorted trigonal non-coplanar geometry to one K1+ and two Ge+3.50+ atoms. In the sixth Se2- site, Se2- is bonded in a 3-coordinate geometry to one K1+ and two Ge+3.50+ atoms. In the seventh Se2- site, Se2- is bonded in a 2-coordinate geometry to three equivalent K1+ and two Ge+3.50+ atoms. In the eighth Se2- site, Se2- is bonded in a 2-coordinate geometry to one K1+ and two Ge+3.50+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on K(MoO2)4 by Materials Project

K(MoO2)4 crystallizes in the tetragonal P4/n space group. The structure is three-dimensional. there are two inequivalent K1+ sites. In the first K1+ site, K1+ is bonded in a body-centered cubic geometry to eight O2- atoms. There are four shorter (3.01 Å) and four longer (3.16 Å) K–O bond lengths. In the second K1+ site, K1+ is bonded in a body-centered cubic geometry to eight O2- atoms. There are four shorter (3.08 Å) and four longer (3.12 Å) K–O bond lengths. There are two inequivalent Mo+3.75+ sites. In the first Mo+3.75+ site, Mo+3.75+ is bonded to six O2- atoms to form a mixture of corner and edge-sharing MoO6 octahedra. The corner-sharing octahedra tilt angles range from 48–55°. There are a spread of Mo–O bond distances ranging from 2.07–2.15 Å. In the second Mo+3.75+ site, Mo+3.75+ is bonded to six O2- atoms to form a mixture of corner and edge-sharing MoO6 octahedra. The corner-sharing octahedra tilt angles range from 48–53°. There are a spread of Mo–O bond distances ranging from 2.00–2.16 Å. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded in a 5-coordinate geometry to two K1+ and three Mo+3.75+ atoms. In the second O2- site, O2- is bonded in a trigonal planar geometry to three Mo+3.75+ atoms. In the third O2- site, O2- is bonded in a distorted trigonal planar geometry to three Mo+3.75+ atoms. In the fourth O2- site, O2- is bonded in a 5-coordinate geometry to two K1+ and three Mo+3.75+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on K(FeS)2 by Materials Project

KFe2S2 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. K is bonded in a body-centered cubic geometry to eight equivalent S atoms. All K–S bond lengths are 3.31 Å. Fe is bonded to four equivalent S atoms to form a mixture of edge and corner-sharing FeS4 tetrahedra. All Fe–S bond lengths are 2.19 Å. S is bonded in a 8-coordinate geometry to four equivalent K and four equivalent Fe atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on K(CrS2)2 by Materials Project

K(CrS2)2 crystallizes in the hexagonal P-6m2 space group. The structure is two-dimensional and consists of one K(CrS2)2 sheet oriented in the (0, 0, 1) direction. K1+ is bonded in a 6-coordinate geometry to six equivalent S2- atoms. All K–S bond lengths are 3.09 Å. Cr+3.50+ is bonded to six S2- atoms to form edge-sharing CrS6 octahedra. There are three shorter (2.35 Å) and three longer (2.46 Å) Cr–S bond lengths. There are two inequivalent S2- sites. In the first S2- site, S2- is bonded in a distorted trigonal non-coplanar geometry to three equivalent Cr+3.50+ atoms. In the second S2- site, S2- is bonded to three equivalent K1+ and three equivalent Cr+3.50+ atoms to form a mixture of distorted edge, face, and corner-sharing SK3Cr3 octahedra. The corner-sharing octahedral tilt angles are 39°.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on K(WO3)3 by Materials Project

K(WO3)3 crystallizes in the triclinic P1 space group. The structure is three-dimensional. there are two inequivalent K1+ sites. In the first K1+ site, K1+ is bonded to twelve O2- atoms to form distorted KO12 cuboctahedra that share edges with twelve WO6 octahedra and faces with two equivalent KO12 cuboctahedra. There are a spread of K–O bond distances ranging from 3.23–3.48 Å. In the second K1+ site, K1+ is bonded to twelve O2- atoms to form distorted KO12 cuboctahedra that share edges with twelve WO6 octahedra and faces with two equivalent KO12 cuboctahedra. There are a spread of K–O bond distances ranging from 3.22–3.48 Å. There are six inequivalent W+5.67+ sites. In the first W+5.67+ site, W+5.67+ is bonded to six O2- atoms to form WO6 octahedra that share corners with six WO6 octahedra and edges with four KO12 cuboctahedra. The corner-sharing octahedra tilt angles range from 5–32°. There are a spread of W–O bond distances ranging from 1.93–2.00 Å. In the second W+5.67+ site, W+5.67+ is bonded to six O2- atoms to form WO6 octahedra that share corners with six WO6 octahedra and edges with four KO12 cuboctahedra. The corner-sharing octahedra tilt angles range from 5–33°. There are a spread of W–O bond distances ranging from 1.90–1.97 Å. In the third W+5.67+ site, W+5.67+ is bonded to six O2- atoms to form WO6 octahedra that share corners with six WO6 octahedra and edges with four KO12 cuboctahedra. The corner-sharing octahedra tilt angles range from 5–32°. There are a spread of W–O bond distances ranging from 1.92–1.96 Å. In the fourth W+5.67+ site, W+5.67+ is bonded to six O2- atoms to form WO6 octahedra that share corners with six WO6 octahedra and edges with four KO12 cuboctahedra. The corner-sharing octahedra tilt angles range from 5–33°. There are a spread of W–O bond distances ranging from 1.92–1.96 Å. In the fifth W+5.67+ site, W+5.67+ is bonded to six O2- atoms to form WO6 octahedra that share corners with six WO6 octahedra and edges with four KO12 cuboctahedra. The corner-sharing octahedra tilt angles range from 6–33°. There are a spread of W–O bond distances ranging from 1.94–2.01 Å. In the sixth W+5.67+ site, W+5.67+ is bonded to six O2- atoms to form WO6 octahedra that share corners with six WO6 octahedra and edges with four KO12 cuboctahedra. The corner-sharing octahedra tilt angles range from 6–32°. There are a spread of W–O bond distances ranging from 1.90–1.97 Å. There are eighteen inequivalent O2- sites. In the first O2- site, O2- is bonded in a linear geometry to two W+5.67+ atoms. In the second O2- site, O2- is bonded in a bent 150 degrees geometry to two K1+ and two W+5.67+ atoms. In the third O2- site, O2- is bonded in a distorted bent 150 degrees geometry to two K1+ and two W+5.67+ atoms. In the fourth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to two K1+ and two W+5.67+ atoms. In the fifth O2- site, O2- is bonded in a linear geometry to two W+5.67+ atoms. In the sixth O2- site, O2- is bonded in a bent 150 degrees geometry to two K1+ and two W+5.67+ atoms. In the seventh O2- site, O2- is bonded in a bent 150 degrees geometry to two K1+ and two W+5.67+ atoms. In the eighth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to two K1+ and two W+5.67+ atoms. In the ninth O2- site, O2- is bonded in a linear geometry to two W+5.67+ atoms. In the tenth O2- site, O2- is bonded in a linear geometry to two W+5.67+ atoms. In the eleventh O2- site, O2- is bonded in a distorted bent 150 degrees geometry to two K1+ and two W+5.67+ atoms. In the twelfth O2- site, O2- is bonded in a bent 150 degrees geometry to two K1+ and two W+5.67+ atoms. In the thirteenth O2- site, O2- is bonded in a bent 150 degrees geometry to two K1+ and two W+5.67+ atoms. In the fourteenth O2- site, O2- is bonded in a linear geometry to two W+5.67+ atoms. In the fifteenth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to two K1+ and two W+5.67+ atoms. In the sixteenth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to two K1+ and two W+5.67+ atoms. In the seventeenth O2- site, O2- is bonded in a bent 150 degrees geometry to two K1+ and two W+5.67+ atoms. In the eighteenth O2- site, O2- is bonded in a linear geometry to two W+5.67+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on K(FeTe)2 by Materials Project

KFe2Te2 is Parent of FeAs superconductors-derived structured and crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. K is bonded in a body-centered cubic geometry to eight equivalent Te atoms. All K–Te bond lengths are 3.58 Å. Fe is bonded in a 8-coordinate geometry to four equivalent Fe and four equivalent Te atoms. All Fe–Fe bond lengths are 2.74 Å. All Fe–Te bond lengths are 2.64 Å. Te is bonded in a 8-coordinate geometry to four equivalent K and four equivalent Fe atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on K(FeSe)2 by Materials Project

KFe2Se2 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. K is bonded in a body-centered cubic geometry to eight equivalent Se atoms. All K–Se bond lengths are 3.40 Å. Fe is bonded to four equivalent Se atoms to form a mixture of distorted edge and corner-sharing FeSe4 tetrahedra. All Fe–Se bond lengths are 2.49 Å. Se is bonded in a 8-coordinate geometry to four equivalent K and four equivalent Fe atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2021

The cross-section measurement for the 3 H($e, e'K^+)nnΛ$ reaction

The small binding energy of the hypertriton leads to predictions of the non-existence of bound hypernuclei for isotriplet three-body systems such as nnΛ. However, invariant mass spectroscopy at GSI has reported events that may be interpreted as the bound nnΛ state. The nnΛ state was sought by missing-mass spectroscopy via the (e, e'K + ) reaction at Jefferson Lab’s experimental Hall A. The present experiment has higher sensitivity to the nnΛ-state investigation in terms of better precision by a factor of about three. The analysis shown in this article focuses on the derivation of the reaction cross-section for the 3 H(γ*, K + )X reaction. Events that were detected in an acceptance, where a Monte Carlo simulation could reproduce the data well (|δp/p| < 4%), were analyzed to minimize the systematic uncertainty. No significant structures were observed with the acceptance cuts, and the upper limits of the production cross-section of the nnΛ state were obtained to be 21 and $31 nbsr -1 at the 90% confidence level when theoretical predictions of (-B Λ , Γ) = (0.25, 0.8) MeV and (0.55, 4.7) MeV, respectively, were assumed. The cross-section result provides valuable information for examining the existence of nnΛ.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2022

Spectroscopic study of a possible $Λnn$ resonance and a pair of $ΣNN$ states using the $(e,e'K^+)$ reaction with a tritium target

Here, a mass spectroscopy experiment with a pair of nearly identical high resolution spectrometers and a tritium target was performed in Hall A at Jefferson Lab. Utilizing the (e,e'K + ) reaction, enhancements, which may correspond to a possible $\Lambda$nn resonance and a pair of ΣNN states, were observed with an energy resolution of about 1.21 MeV (σ), although greater statistics are needed to make definitive identifications. An experimentally measured Λnn state may provide a unique constraint in determining the Λn interaction, for which no scattering data exist. In addition, although bound A = 3 and 4 Σ hypernuclei have been predicted, only an A = 4 Σ hypernucleus ($^4_Σ$He) was found, utilizing the (K - ,π - ) reaction on a 4 He target. The possible bound ΣNN state is likely a Σ 0 nn state, although this has to be confirmed by future experiments.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2022

Combined analysis of Belle and Belle II data to determine the CKM angle φ 3 using B + → D($ {K}_S^0 $h + h – )h + decays

We present a measurement of the Cabibbo-Kobayashi-Maskawa unitarity triangle angle φ 3 (also known as γ) using a model-independent Dalitz plot analysis of B + → D($ {K}_S^0 $h + h – )h + , where D is either a D o or D o ¯ meson and h is either a π or K. This is the first measurement that simultaneously uses Belle and Belle II data, combining samples corresponding to integrated luminosities of 711 fb –1 and 128 fb –1 , respectively. All data were accumulated from energy-asymmetric e + e – collisions at a centre-of-mass energy corresponding to the mass of the Υ(4S) resonance. We measure φ 3 = (78.4 ± 11.4 ± 0.5 ± 1.0)°, where the first uncertainty is statistical, the second is the experimental systematic uncertainty and the third is from the uncertainties on external measurements of the D-decay strong-phase parameters.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2025

Search for lepton flavor-violating decay modes B 0 → K* 0 τ ± ℓ ∓ (ℓ = e, μ) with hadronic B-tagging at Belle and Belle II

We present the results of a search for the charged-lepton-flavor violating decays B 0 → K *0 τ ± ℓ ∓ , where ℓ ∓ is either an electron or a muon. The results are based on 365 fb −1 and 711 fb −1 datasets collected with the Belle II and Belle detectors, respectively. We use an exclusive hadronic B-tagging technique, and search for a signal decay in the system recoiling against a fully reconstructed B meson. We find no evidence for B 0 → K* 0 τ ± ℓ ∓ decays and set upper limits on the branching fractions in the range of (2.9–6.4)×10 −5 at 90% confidence level.

B physics↗
DOE OSTI2023

First Direct Measurement Constraining the Ar 34 ( α , p ) K 37 Reaction Cross Section for Mixed Hydrogen and Helium Burning in Accreting Neutron Stars

The rate of the final step in the astrophysical αp process, the 34 Ar(α,p) 37 K reaction, suffers from large uncertainties due to a lack of experimental data, despite having a considerable impact on the observable light curves of x-ray bursts and the composition of the ashes of hydrogen and helium burning on accreting neutron stars. Here, we present the first direct measurement constraining the 34Ar(α,p)37K reaction cross section, using the Jet Experiments in Nuclear Structure and Astrophysics gas jet target. The combined cross section for the 34 Ar,Cl(α,p) 37 K,Ar reaction is found to agree well with Hauser-Feshbach predictions. The 34 Ar(α,2p) 36 Ar cross section, which can be exclusively attributed to the 34 Ar beam component, also agrees to within the typical uncertainties quoted for statistical models. This indicates the applicability of the statistical model for predicting astrophysical (α,p) reaction rates in this part of the αp process, in contrast to earlier findings from indirect reaction studies indicating orders-of-magnitude discrepancies. This removes a significant uncertainty in models of hydrogen and helium burning on accreting neutron stars.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2025

Observation of the ${K}^{+}\to {\pi}^{+}\nu \overline{\nu}$ decay and measurement of its branching ratio

A measurement of the ${K}^{+}\to {\pi}^{+}\nu \overline{\nu}$ decay by the NA62 experiment at the CERN SPS is presented, using data collected in 2021 and 2022. This dataset was recorded, after modifications to the beamline and detectors, at a higher instantaneous beam intensity with respect to the 2016–2018 data taking. Combining NA62 data collected in 2016–2022, a measurement $\mathcal{B} ({K}^{+}\to {\pi}^{+}\nu \overline{\nu}) = \large{(}13.0^{+3.3}_{-3.0}\large{)}$ x $10^{-11}$ of is reported. With 51 signal candidates observed and an expected background of $18^{+3}_{-2}$ events, $\mathcal{B} ({K}^{+}\to {\pi}^{+}\nu \overline{\nu})$ becomes the smallest branching ratio measured with a signal significance above 5σ.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2021

Search for a feebly interacting particle X in the decay K + → π + X

A search for the K + → π + X decay, where X is a long-lived feebly interacting particle, is performed through an interpretation of the K + → π + $\overline{vv}$ analysis of data collected in 2017 by the NA62 experiment at CERN. Two ranges of X masses, 0–110 MeV/c 2 and 154–260 MeV/c 2 , and lifetimes above 100 ps are considered. The limits set on the branching ratio, BR(K + → π + X), are competitive with previously reported searches in the first mass range, and improve on current limits in the second mass range by more than an order of magnitude.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗