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At least 109 records · Page 6
All sourcesNASA NTRSDOE OSTI
DOE OSTI2025

Study of Λ b 0 and Ξ b 0 Decays to Λ h + h ′ − and Evidence for C P Violation in Λ b 0 → Λ K + K − Decays

A study of Λ b 0 and Ξ b 0 decays to Λ h + h ′ − ( h ( ′ ) = π , K ) is performed using p p collision data collected by the LHCb experiment during LHC Runs 1–2, corresponding to an integrated luminosity of 9 fb − 1 . The branching fractions for these decays are measured using the Λ b 0 → Λ c + ( → Λ π + ) π − decay as a control channel. The decays Λ b 0 → Λ π + π − and Ξ b 0 → Λ K − π + are observed for the first time. For decay modes with sufficient signal yields, C P asymmetries are measured in the full and localized regions of the final-state phase space. Evidence is found for C P violation in the Λ b 0 → Λ K + K − decay, interpreted as originating primarily from an asymmetric Λ b 0 → N * + K − decay amplitude. The measured C P asymmetries for other decays are compatible with zero. © 2025 CERN, for the LHCb Collaboration 2025 CERN

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

Pattern of global spin alignment of ϕ and K*0 mesons in heavy-ion collisions

The strong force, as one of the four fundamental forces at work in the universe, governs interactions of quarks and gluons, and binds together the atomic nucleus. Notwithstanding decades of progress since Yukawa first developed a description of the force between nucleons in terms of meson exchange 1 , a full understanding of the strong interaction remains a major challenge in modern science. One remaining difficulty arises from the non-perturbative nature of the strong force, which leads to the phenomenon of quark confinement at distance scales on the order of the size of the proton. Here we show that in relativistic heavy-ion collisions, where quarks and gluons are set free over an extended volume, two species of produced vector (spin-1) mesons, namely φ and K∗0 , emerge with a surprising pattern of global spin alignment. In particular, the global spin alignment for φ is unexpectedly large, while that for K∗0 is consistent with zero. The observed spin-alignment pattern and magnitude for the φ cannot be explained by conventional mechanisms, while a model with strong force fields2, 3 accommodates the current data. This is the first time that the strong force field is experimentally supported as a key mechanism that leads to global spin alignment. We extract a quantity proportional to the intensity of the field of the strong force. Within the framework of the Standard Model, where the strong force is typically described in the quark and gluon language of Quantum Chromodynamics, the field being considered here is an effective proxy description. This is a qualitatively new class of measurement, which opens a new avenue for studying the behaviour of strong force fields via their imprint on spin alignment.

Abdallah, M. S.↗
DOE OSTI2025

Measurement of the time-integrated C P asymmetry in D 0 → K S 0 K S 0 decays using Belle and Belle II data

We measure the time-integrated C P asymmetry in D 0 → K S 0 K S 0 decays reconstructed in e + e − → c c ¯ events collected by the Belle and Belle II experiments. The corresponding data samples have integrated luminosities of 980 and 428 fb − 1 , respectively. The D 0 decays are required to originate from the D * + → D 0 π + decay, which determines the charm flavor at production time. A control sample of D 0 → K + K − decays is used to correct for production and detection asymmetries. The result, ( − 1.4 ± 1.3 ( stat ) ± 0.1 ( syst ) ) % , is consistent with previous determinations and with C P symmetry. Published by the American Physical Society 2025

Adachi, I. (ORCID:0000000322870173)↗
DOE OSTI2022

Observation of the Y(4230) and a new structure in ${\boldsymbol e^+\boldsymbol e^- \boldsymbol\rightarrow \boldsymbol K^+\boldsymbol K^-\boldsymbol J/\boldsymbol\psi}$

The cross sections of $e^+e^- \rightarrow K^+K^-J/\psi$ at center-of-mass energies from 4.127 to 4.600 GeV are measured based on 15.6 fb -1 data collected with the BESIII detector operating at the BEPCII storage ring. Two resonant structures are observed in the line shape of the cross sections. The mass and width of the first structure are measured to be ($4225.3\pm2.3\pm21.5$) MeV and ($72.9\pm6.1\pm30.8$) MeV, respectively. They are consistent with those of the established $Y(4230)$. The second structure is observed for the first time with a statistical significance greater than 8σ, denoted as $Y(4500)$. Its mass and width are determined to be ($4484.7\pm13.3\pm24.1$) MeV and ($111.1\pm30.1\pm15.2$) MeV, respectively. The first presented uncertainties are statistical and the second ones are systematic. The product of the electronic partial width with the decay branching fraction $\Gamma(Y(4230)\to e^+ e^-) \mathcal{B}(Y(4230) \to K^+ K^- J/\psi)$ is reported.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2024

Search for e + e − → K + K − ψ ( 3770 ) at center-of-mass energies from 4.84 to 4.95 GeV

Using e + e − collision data, corresponding to an integrated luminosity of 892 pb − 1 collected at center-of-mass energies from 4.84 to 4.95 GeV with the BESIII detector, we search for the process e + e − → K + K − ψ ( 3770 ) by reconstructing two charged kaons and one D meson from ψ ( 3770 ) . No significant signal of e + e − → K + K − ψ ( 3770 ) is found and the upper limits of the Born cross sections are reported at 90% confidence level. Published by the American Physical Society 2024

Astronomy & Astrophysics↗
DOE OSTI2024

Determination of Spin-Parity Quantum Numbers of X ( 2370 ) as 0 − + from J / ψ → γ K S 0 K S 0 η ′

Based on ( 10 087 ± 44 ) × 10 6 J / ψ events collected with the BESIII detector, a partial wave analysis of the decay J / ψ → γ K S 0 K S 0 η ′ is performed. The mass and width of the X ( 2370 ) are measured to be 2395 ± 11 ( stat ) − 94 + 26 ( syst ) MeV / c 2 and 188 − 17 + 18 ( stat ) − 33 + 124 ( syst ) MeV , respectively. The corresponding product branching fraction is B [ J / ψ → γ X ( 2370 ) ] × B [ X ( 2370 ) → f 0 ( 980 ) η ′ ] × B [ f 0 ( 980 ) → K S 0 K S 0 ] = ( 1.31 ± 0.22 ( stat ) − 0.84 + 2.85 ( syst ) ) × 10 − 5 . The statistical significance of the X ( 2370 ) is greater than 11.7 σ and the spin parity is determined to be 0 − + for the first time. The measured mass and spin parity of the X ( 2370 ) are consistent with the predictions of the lightest pseudoscalar glueball. Published by the American Physical Society 2024

Physics↗
DOE OSTI2024

Three-particle formalism for multiple channels: the ηππ + $ K\overline{K}\pi $ system in isosymmetric QCD

We generalize previous three-particle finite-volume formalisms to allow for multiple three-particle channels. For definiteness, we focus on the two-channel ηππ and $ K\overline{K}\pi $ system in isosymmetric QCD, considering the positive G parity sector of the latter channel, and neglecting the coupling to modes with four or more particles. The formalism we obtain is thus appropriate to study the b 1 (1235) and η(1295) resonances. The derivation is made in the generic relativistic field theory approach using the time-ordered perturbation theory method. We study how the resulting quantization condition reduces to that for a single three-particle channel when one drops below the upper ($ K\overline{K}\pi $) threshold. We also present parametrizations of the three-particle K matrices that enter into the formalism.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2025

Physical-mass calculation of ρ ( 770 ) and K * ( 892 ) resonance parameters via π π and K π scattering amplitudes from lattice QCD

We present our study of the ρ ( 770 ) and K * ( 892 ) resonances from lattice quantum chromodynamics (QCD) employing domain-wall fermions at physical quark masses. We determine the finite-volume energy spectrum in various momentum frames and obtain phase-shift parametrizations via the Lüscher formalism and as a final step the complex resonance poles of the π π and K π elastic scattering amplitudes via an analytical continuation of the models. By sampling a large number of representative sets of underlying energy-level fits, we also assign a systematic uncertainty to our final results. This is a significant extension to data-driven analysis methods that have been used in lattice QCD to date, due to the two-step nature of the formalism. Our final pole positions, M + i Γ / 2 , with all statistical and systematic errors exposed, are M K * = 893 ( 2 ) ( 8 ) ( 54 ) ( 2 ) MeV and Γ K * = 51 ( 2 ) ( 11 ) ( 3 ) ( 0 ) MeV for the K * ( 892 ) resonance and M ρ = 796 ( 5 ) ( 15 ) ( 48 ) ( 2 ) MeV and Γ ρ = 192 ( 10 ) ( 28 ) ( 12 ) ( 0 ) MeV for the ρ ( 770 ) resonance. The four differently grouped sources of uncertainties are, in the order of occurrence: statistical, data-driven systematic, an estimation of systematic effects beyond our computation (dominated by the fact that we employ a single lattice spacing), and the error from the scale-setting uncertainty on our ensemble. Published by the American Physical Society 2025

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2020

The crystal structure of TlMgCl 3 from 290 K to 725 K

The title compound, thallium magnesium trichloride, has been identified as a scintillator with both moderate gamma-stopping power and moderate light yield. Knowledge of its crystal structure is needed for further development. This work determines the crystal structure of TlMgCl 3 to be hexa­gonal P6 3 /mmc (No. 194) and isostructural with RbMgCl 3 , contrary to previously reported data. This structure was obtained by single-crystal X-ray diffraction and was further confirmed by neutron diffraction measurements. Extending neutron diffraction measurements to high temperature, the data show that TlMgCl 3 maintains this crystal structure from 290 K up through 725 K, approaching the melting point of 770 K. Anisotropic thermal expansion coefficients increase over this temperature range, from 31 to 38 × 10 –6 K –1 along the a axis and from 19 to 34 × 10 –6 K –1 along the c axis.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Sound velocities of iron-nickel (Fe90Ni10) alloy up to 8 GPa and 773 K: The effect of nickel on the elastic properties of bcc-iron at high P-T

Sound velocities of iron and iron-based alloys at high pressure and high temperature are crucial for understanding the composition and structure of Earth’s and other telluric planetary cores. In this study, we performed ultrasonic interferometric measurements of both compressional (ν P ) and shear (ν S ) velocities on a polycrystalline body-centered-cubic (bcc)-Fe 90 Ni 10 up to 8 GPa and 773 K. The elastic moduli and their pressure and temperature derivatives are derived from least-square fits to third-order finite strain equations, yielding K S0 = 154.2(8) GPa, G 0 = 73.2(2) GPa, K' S0 = 4.6(2), G' 0 = 1.5(1), ∂K S /∂T = –0.028(1) GPa/K, and ∂G/∂T = –0.023(1) GPa/K. Furthermore, a comparison with literature data on bcc-Fe suggests that nickel not only decreases both P and S wave velocities but also weakens the temperature effects on the elastic moduli of Fe-Ni alloys.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Search for rare decays B + → D s ( * ) + η , D s ( * ) + K ¯ 0 , D + η , and D + K 0

We present a study of rare decay modes B + → D$^{+}_{s}$ℎ 0 , B + → D$^{*}_{s}$⁢ + ℎ 0 , and B + → D + ⁢ℎ 0 , where ℎ 0 denotes the neutral meson η or K 0 , using a data sample of (772 ±10) ×10 6 B$\overline{B}$ events produced at the Υ⁡(4⁢S) resonance. The data were collected by the Belle detector operating at the asymmetric-energy KEKB collider. We find no evidence for these decays, so we set upper limits at the 90% confidence level on the branching fractions of , , and D + ⁢ℎ 0 decay modes. Along with these rare decay modes, we report improved measurements of the color-suppressed decay branching fractions $\mathscr{B}$⁡($\overline{B}$ 0 →D 0 ⁢η) =(26.6 ±1.2 ±2.1) ×10 -5 and $\mathscr{B}$⁡($\overline{B}$) 0 →D 0 ⁢ $\overline{K}$ 0 ) =(5.6 ±0.5 ±0.2) ×10 -5 . The first and second quoted uncertainties are statistical and systematic, respectively.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2024

Search for η c ( 2 S ) → π + π − η c and η c ( 2 S ) → π + π − K S 0 K ± π ∓ decays

Based on ( 27.12 ± 0.14 ) × 10 8 ψ ( 2 S ) events collected by the BESIII detector, we search for the decay η c ( 2 S ) → π + π − η c via ψ ( 2 S ) → γ η c ( 2 S ) . No significant signal is observed, and the upper limit on the product branching fraction B ( ψ ( 2 S ) → γ η c ( 2 S ) ) × B ( η c ( 2 S ) → π + π − η c ) is determined to be 2.21 × 10 − 5 at the 90% confidence level. In addition, the η c ( 2 S ) → π + π − K S 0 K ± π ∓ decay is studied via ψ ( 2 S ) → γ η c ( 2 S ) and is observed with a statistical significance of 10 σ for the first time. The branching fraction of η c ( 2 S ) → π + π − K S 0 K ± π ∓ is determined to be ( 1.33 ± 0.11 ± 0.40 ± 0.95 ) × 10 − 2 , where the first uncertainty is statistical, the second is systematic, and the third uncertainty is due to the quoted B ( ψ ( 2 S ) → γ η c ( 2 S ) ) . Published by the American Physical Society 2024

Astronomy & Astrophysics↗
DOE OSTI2023

Evidence for the singly Cabibbo-suppressed decay Ω 0 c → Ξ¯π + and search for Ω 0 c → Ξ¯ K + and Ω¯K + decays at Belle

Using a data sample of 980 fb -1 collected with the Belle detector at the KEKB asymmetric-energy e + e - collider, we study for the first time the singly Cabibbo-suppressed decays Ω 0 c → Ξ¯π + and Ω¯K + and the doubly Cabibbo-suppressed decay Ω 0 c → Ξ¯ K + . Evidence for an Ω 0 c signal in the Ω 0 c → Ξ¯π + mode is reported with a significance of 4.5σ including systematic uncertainties.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2021

Mutual Diffusion Coefficients and Refractive Index Increments of K 2 SO 4 (aq) at 298.15 K from Rayleigh Interferometry

Here, isothermal mutual diffusion coefficients (interdiffusion coefficients) were measured for K 2 SO 4 (aq) at 298.15 ± 0.005 K, at numerous concentrations ranging from dilute solutions to near saturation (0.59648 mol∙dm -3 ; 0.61349 mol∙kg -1 ) under free diffusion boundary conditions, using high precision Rayleigh interferometry. Under the experimental conditions these diffusion coefficients are on the volume-fixed reference frame D v . Two series of experiments were performed, the first using the traditional experimental approach with a mercury lamp source and with the interference patterns being recorded on glass photographic plates, and the second with a He-Ne laser light source and computerized data acquisition using a photodiode array. The results from both series of experiments are in excellent agreement, and generally yield diffusion coefficients precise to at least 0.002 x 10 -9 m 2 ∙s 1 (0.15% to 0.19%) and in most cases to 0.001 x 10 -9 m 2 ∙s -1 (0.07% to 0.1%). These experiments also yield accurate values of the refractive index differences for the solution pairs used in the diffusion experiments. The new diffusion coefficients are compared to two sets of published values of diffusion coefficients for K 2 SO 4 (aq) which are somewhat discrepant from each other. This study extends and complements our earlier work on the diffusion coefficients of the most common brine salts: NaCl(aq), KCl(aq), MgCl 2 (aq), CaCl 2 (aq), Na 2 SO 4 (aq), ] MgSO 4 (aq), NaHCO 3 (aq), and KHCO 3 (aq) at 298.15 K.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2021

Measurement of the CP-violating phase ϕs in the B s 0 → J / ψ ϕ ( 1020 ) → μ + μ − K + K − channel in proton-proton collisions at s = 13 TeV

The CP -violating weak phase ϕ s and the decay width difference Δ Γ s between the light and heavy B s 0 mass eigenstates are measured with the CMS detector at the LHC in a sample of 48 500 reconstructed B s 0 → J / ψ ϕ ( 1020 ) → μ + μ − K + K − events. The measurement is based on a data sample corresponding to an integrated luminosity of 96.4 fb − 1 , collected in proton-proton collisions at s = 13 TeV in 2017–2018. To extract the values of ϕ s and Δ Γ s , a time-dependent and flavor-tagged angular analysis of the μ + μ − K + K − final state is performed. The analysis employs a dedicated tagging trigger and a novel opposite-side muon flavor tagger based on machine learning techniques. The measurement yields ϕ s = − 11 ± 50 (stat) ± 10 (syst) mrad and Δ Γ s = 0.114 ± 0.014 (stat) ± 0.007 (syst) ps − 1 , in agreement with the standard model predictions. When combined with the previous CMS measurement at s = 8 TeV , the following values are obtained: ϕ s = − 21 ± 44 (stat) ± 10 (syst) mrad , Δ Γ s = 0.1032 ± 0.0095 (stat) ± 0.0048 (syst) ps − 1 , a significant improvement over the 8 TeV result.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2020

K 3 Ir 2 O 6 and K 16.3 Ir 8 O 30 , Low-Dimensional Iridates with Infinite IrO 6 Chains

A previously unreported 1D iridate, K 3 Ir 2 O 6 , has been grown by a flux method in O 2 -rich environment and its crystal structure determined via single crystal structural analysis. It exhibits straight chains of face-sharing [IrO 6 ] octahedra, which are arranged along the crystallographic c axis, separated by nonmagnetic K ions. No magnetic transitions are observed during measured range, and the material is electrically insulating. Potentially interesting electronic behavior for K 3 Ir 2 O 6 is supported by electronic structure calculations. A structurally related material, K 16.3 Ir 8 O 30 , which displays similar fundamental geometric units but in a different spatial arrangement – zigzag chains based on edge and face sharing [IrO 6 ] octahedra, is also reported. Both materials are of interest for probing the properties of a 1D system with strong spin-orbit coupling

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2021

Thermomagnetic properties of Bi 2 Te 3 single crystal in the temperature range from 55 K to 380 K

Magnetothermoelectric transport provides an understanding of coupled electron-hole-phonon current in topological materials and has applications in energy conversion and cooling. In this paper, we study the Nernst coefficient, the magneto-Seebeck coefficient, and the magnetoresistance of single-crystalline Bi 2 Te 3 under external magnetic field in the range of –3T to 3T and in the temperature range of 55 K to 380 K. Moreau's relation is employed to justify both the overall trend of the Nernst coefficient and the temperature at which this coefficient changes sign. We observe a nonlinear relationship between the Nernst coefficient and the applied magnetic field in the temperature range of 55 K to 255 K. An increase in both the Nernst coefficient and the magneto-Seebeck coefficient is observed as the temperature is reduced which can be attributed to the increased mobility of the carriers at lower temperatures. First-principles density functional theory calculations were carried out to physically model the experimental data including electronic and transport properties. Simulation findings agreed with the experiments and provide a theoretical insight to justify the measurements.

36 MATERIALS SCIENCE↗