Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “ISOSPIN”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 685 records · Page 38
All sourcesNASA NTRSDOE OSTI
DOE OSTI2023

Amplitude analysis of B 0 → D ¯ 0 D s + π - and B + → D - D s + π + decays

Resonant contributions in B 0 → D ¯ 0 D s + π - and B + → D - D s + π + decays are determined with an amplitude analysis, which is performed both separately and simultaneously, where in the latter case isospin symmetry between the decays is assumed. The analysis is based on data collected by the LHCb detector in proton-proton collisions at center-of-mass energies of 7, 8, and 13 TeV. The full data sample corresponds to an integrated luminosity of 9 fb -1 . A doubly charged spin-0 open-charm tetraquark candidate together with a neutral partner, both with masses near 2.9 GeV, are observed in the $D_sπ$ decay channel.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2023

Update of Euclidean windows of the hadronic vacuum polarization

We compute the standard Euclidean window of the hadronic vacuum polarization using multiple independent blinded analyses. We improve the continuum and infinite-volume extrapolations of the dominant quark-connected light-quark isospin-symmetric contribution and address additional subleading systematic effects from sea-charm quarks and residual chiral-symmetry breaking from first principles. We find 𝑎$^{W}_{μ}$ = 235.56⁢(65)⁢(50) × 10 −10 , which is in 3.8⁢𝜎 tension with the recently published dispersive result of 𝑎$^{W}_{μ}$ =229.4⁢(1.4) × 10 −10 [G. Colangelo, A. X. El-Khadra, M. Hoferichter, A. Keshavarzi, C. Lehner, P. Stoffer, and T. Teubner, Phys. Lett. B 833, 137313 (2022)] and in agreement with other recent lattice determinations. We also provide a result for the standard short-distance window. The results reported here are unchanged compared to our presentation at the Edinburgh workshop of the g-2 Theory Initiative in 2022 [C. Lehner, Talk Presented at the 5th Plenary Meeting of the g-2 Theory Initiative in Edinburgh (2022)].

Lattice QCD↗
DOE OSTI2023

Transverse Λ polarization in 𝑒 +⁢ 𝑒 − annihilations and in SIDIS processes at the EIC within TMD factorization

We present a phenomenological study on the role of charm contribution and SU(2) isospin symmetry in the extraction of the Λ polarizing fragmentation functions from e + e – → Λ ↑ ($\overline{Λ}$ ↑ )h+X annihilation processes. We adopt the well-established transverse-momentum-dependent factorization formalism, within the Collins-Soper-Sterman evolution scheme at next-to-leading logarithm accuracy, carefully exploiting the role of the nonperturbative component of the polarizing fragmentation function. We then discuss the impact of these results on the predictions for transverse Λ, $\overline{Λ}$ polarization in semi-inclusive deep inelastic scattering processes at typical energies of the future Electron-Ion Collider.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2024

Measurement of branching fractions and direct C P asymmetries for B → K π and B → π π decays at Belle II

We report measurements of the branching fractions and direct C P asymmetries of the decays B 0 → K + π − , B + → K + π 0 , B + → K 0 π + , and B 0 → K 0 π 0 , and use these for testing the standard model through an isospin-based sum rule. In addition, we measure the branching fraction and direct C P asymmetry of the decay B + → π + π 0 and the branching fraction of the decay B 0 → π + π − . The data are collected with the elle II detector from e + e − collisions at the ϒ ( 4 S ) resonance produced by the SuperKEKB asymmetric-energy collider and contain 387 × 10 6 bottom-antibottom meson pairs. Signal yields are determined in two-dimensional fits to background-discriminating variables, and range from 500 to 3900 decays, depending on the channel. We obtain − 0.03 ± 0.13 ± 0.04 for the sum rule in agreement with the standard model expectation of zero and with a precision comparable to the best existing determinations. Published by the American Physical Society 2024

Astronomy & Astrophysics↗
DOE OSTI2024

Observation and branching fraction measurement of the decay J / ψ → p ¯ Σ + K S 0 + c . c .

The first observation of the decays J / ψ → p ¯ Σ + K S 0 and J / ψ → p Σ ¯ − K S 0 is reported using ( 10087 ± 44 ) × 10 6 J / ψ events recorded by the BESIII detector at the BEPCII storage ring. The branching fractions of each channel are determined to be B ( J / ψ → p ¯ Σ + K S 0 ) = ( 1.361 ± 0.006 ± 0.025 ) × 10 − 4 , and B ( J / ψ → p Σ ¯ − K S 0 ) = ( 1.352 ± 0.006 ± 0.025 ) × 10 − 4 . The combined result is B ( J / ψ → p ¯ Σ + K S 0 + c . c . ) = ( 2.725 ± 0.009 ± 0.050 ) × 10 − 4 , where the first uncertainty is statistical and the second systematic. The results presented are in good agreement with the branching fractions of the isospin partner decay J / ψ → p K − Σ ¯ 0 + c . c . Published by the American Physical Society 2024

Astronomy & Astrophysics↗
DOE OSTI2024

Determination of crossing-symmetric π π scattering amplitudes and the quark mass evolution of the σ constrained by lattice QCD

Lattice QCD spectra can be used to constrain partial-wave scattering amplitudes that, while satisfying unitarity, do not have to respect crossing symmetry and analyticity. This becomes a particular problem when extrapolated far from real energies, e.g. in the case of broad resonances like the σ , leading to large systematic uncertainties in the pole position. In this manuscript, we will show how dispersion relations can implement the additional constraints, using as input lattice-determined π π partial-wave scattering amplitudes with isospin–0,1,2. We will show that only certain combinations of amplitude parametrizations satisfy all constraints, and that when we restrict to these, the σ pole position is determined with minimal systematic uncertainty. The evolution of the now well-constrained σ pole with varying light quark mass is presented, showing how it transitions from a bound-state to a broad resonance. Published by the American Physical Society 2024

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2024

First observation of the decay Λ c + → n K S 0 π + π 0

Based on 4.5 fb − 1 of e + e − collision data accumulated at center-of-mass energies between 4599.53 and 4698.82 MeV with the BESIII detector, the decay Λ c + → n K S 0 π + π 0 is observed for the first time with a significance of 9.2 σ . The branching fraction is measured to be ( 0.85 ± 0.13 ± 0.03 ) % , where the first uncertainty is statistical and the second is systematic, which differs from the theoretical prediction based on isospin by 4.4 σ . This indicates that there may be resonant contributions or some unknown dynamics in this decay. Published by the American Physical Society 2024

Astronomy & Astrophysics↗
DOE OSTI2024

First measurements of the absolute branching fraction of Λ c ( 2625 ) + → Λ c + π + π − and upper limit on Λ c ( 2595 ) + → Λ c + π + π −

The absolute branching fraction of the decay Λ c ( 2625 ) + → Λ c + π + π − is measured for the first time to be ( 50.2 ± 5.7 stat ± 3.5 syst ) % with 368.48 pb − 1 of e + e − collision data collected by the BESIII detector at the center-of-mass energies of s = 4.918 and 4.950 GeV. Although the central value of the result is lower than the theoretical prediction of 67%, obtained from isospin symmetry, they are consistent taking the uncertainties into account. This is the first absolute branching fraction measurement for Λ c ( 2625 ) + since it was found. This measurement is necessary to obtain the coupling constants for the transitions between s -wave and p -wave charmed baryons in heavy hadron chiral perturbation theory. In addition, we search for the decay Λ c ( 2595 ) + → Λ c + π + π − . No significant signal is observed, and the upper limit on its branching fraction is determined to be 85.0% at the 90% confidence level. Published by the American Physical Society 2024

Astronomy & Astrophysics↗
DOE OSTI2024

Kaon mixing beyond the standard model with physical masses

We present nonperturbative results for beyond the standard model kaon mixing matrix elements in the isospin symmetric limit ( m u = m d ) of QCD, including a complete estimate of all dominant sources of systematic error. Our results are obtained from numerical simulations of lattice QCD with N f = 2 + 1 flavors of dynamical domain wall fermions. For the first time, these quantities are simulated directly at the physical pion mass m π ∼ 139 MeV for two different lattice spacings. We include data at three lattice spacings in the range a = 0.11 – 0.07 fm and with pion masses ranging from the physical value up to 450 MeV. Compared to our earlier work, we have added both direct calculations at physical quark masses and a third lattice spacing making the removal of discretization effects significantly more precise and eliminating the need for any significant mass extrapolation beyond the range of simulated data. We renormalize the lattice operators nonperturbatively using RI-SMOM off-shell schemes. These schemes eliminate the need to model and subtract nonperturbative pion poles that arises in the RI-MOM scheme and, since the calculations are performed with domain wall fermions, the unphysical mixing between chirality sectors is suppressed. Our results for the bag parameters in the MS ¯ scheme at 3 GeV are B K ≡ B 1 = 0.5240 ( 17 ) ( 54 ) , B 2 = 0.4794 ( 25 ) ( 35 ) , B 3 = 0.746 ( 13 ) ( 17 ) , B 4 = 0.897 ( 02 ) ( 10 ) and B 5 = 0.6882 ( 78 ) ( 94 ) , where the first error is from lattice uncertainties and the second is the uncertainty due to the perturbative matching to MS ¯ . Published by the American Physical Society 2024

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2024

Strangeness-correlations on the pseudocritical line in ( 2 + 1 )-flavor QCD

We present some lattice QCD results on first ( χ 1 i ) and second ( χ 2 i ) cumulants of and correlations ( χ 11 i j ) among net baryon-number ( B ), strangeness ( S ) and electric charge ( Q ) along the pseudocritical line [ T p c ( μ B ) ] in the temperature ( T )–baryon chemical potential ( μ B ) phase diagram of ( 2 + 1 )-flavor QCD. We point out that violations of sum rules among second order cumulants, which hold in the isospin symmetric limit of vanishing electric charge chemical potential, are small along the T p c ( μ B ) for the entire range of μ B covered in the RHIC beam energy scan. For the strangeness neutral matter produced in heavy-ion collisions this leads to a close relation between χ 11 B S and χ 11 Q S . We compare lattice QCD results for χ 11 B S / χ 2 S along the T p c ( μ B ) line with preliminary experimental measurements of χ 11 B S / χ 2 S for collision energies 7.7 GeV ≤ s N N ≤ 62.4 GeV . While we find good agreements for s N N ≥ 39 GeV , differences are sizeable at smaller values of s N N . Moreover, we compare lattice QCD results for the ratio of the strangeness ( μ S ) to baryon ( μ B ) chemical potentials, which define a strangeness neutral system with fixed electric charge to baryon number density, with experimental results obtained by the STAR collaboration for μ S / μ B using strange baryon yields on the freeze-out line. Finally, we determine the baryon chemical potential at the freeze-out ( μ B f ) by comparing χ 1 B / χ 2 B along the T p c ( μ B ) with the experimentally measured net-proton cumulants χ 1 p / χ 2 p . We find that { μ B f , T p c ( μ B f ) } are consistent with the freeze-out parameters of the statistical-model fits to experimentally measured hadron yields for s N N ≥ 11.5 GeV . Published by the American Physical Society 2024

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2024

Unitary coupled-channel three-body amplitude with pions and kaons

Three-body dynamics above threshold is required for the reliable extraction of many amplitudes and resonances from experiment and lattice QCD. The S-matrix principle of unitarity can be used to construct dynamical coupled-channel approaches in which three particles scatter off each other, rearranging two-body subsystems by particle exchange. This paper reports the development of a three-body coupled-channel, amplitude including pions and kaons. The unequal-mass amplitude contains two-body S- and P-wave subsystems (“isobars”) of all isospins, 𝐼 = 0,1/2,1,3/2,2 , and it also allows for transitions within a given isobar. The 𝑓 0 ⁡(500)⁢(𝜎),𝑓 0 ⁡(980),𝜌⁡(700),𝐾$^{*}_{0}$⁡(700)⁢(𝜅), and 𝐾*⁡(892) resonances are included, apart from repulsive isobars. Different methods to evaluate the amplitude for physical momenta are discussed. Production amplitudes for 𝑎 1 quantum numbers are shown as a proof of principle for the numerical implementation.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2025

Data-driven results for light-quark connected and strange-plus-disconnected hadronic g − 2 short- and long-distance windows

A key issue affecting the attempt to reduce the uncertainty on the Standard Model prediction for the muon anomalous magnetic moment is the current discrepancy between lattice-QCD and data-driven results for the hadronic vacuum polarization. Progress on this issue benefits from precise data-driven determinations of the isospin-limit light-quark-connected (lqc) and strange-plus-light-quark-disconnected ( s + lqd ) components of the related RBC/UKQCD windows. In this paper, using a strategy employed previously for the intermediate window, we provide data-driven results for the lqc and s + lqd components of the short- and long-distance RBC/UKQCD windows. Comparing these results with those from the lattice, we find significant discrepancies in the lqc parts but good agreement for the s + lqd components. We also explore the impact of recent CMD- 3 e + e − → π + π − cross section results, demonstrating that an upward shift in the ρ -peak region of the type seen in the CMD-3 data serves to eliminate the discrepancies for the lqc components without compromising the good agreement between lattice and data-driven s + lqd results. Published by the American Physical Society 2025

Benton, Genessa (ORCID:0009000515763654)↗
DOE OSTI2025

Near-threshold states in coupled D D * − D * D * scattering from lattice QCD

The first determination of doubly charmed isospin-0 coupled-channel D D * − D * D * scattering amplitudes from lattice quantum chromodynamics (QCD) is presented. The finite-volume spectrum is computed for three lattice volumes with a light-quark mass corresponding to m π ≈ 391 MeV and is used to extract the scattering amplitudes in J P = 1 + via the Lüscher quantization condition. By analytically continuing the scattering amplitudes to complex energies, a T c c pole corresponding to a virtual bound state is found below D D * threshold. We also find a second pole, T c c ′ , corresponding to a resonance pole below the kinematically closed D * D * channel, to which it has a strong coupling. A nonzero coupling is robustly found between the S -wave D D * and D * D * channels producing a clear cusp in the D D * amplitude at the D * D * threshold energy. This suggests that the experimental T c c ′ should be observable in D D * and D * D * final states at ongoing experiments. Published by the American Physical Society 2025

Whyte, Travis (ORCID:000000027661301X)↗
DOE OSTI2025

Partial-wave projection of relativistic three-body amplitudes

We derive the integral equations for partial-wave projected three-body scattering amplitudes, starting from the integral equations for three-body amplitudes developed for lattice QCD analyses. The results, which hold for generic three-body systems of spinless particles, build upon the recently derived partial-wave projected one-particle exchange, a primary component of the relativistic framework proven to satisfy 𝑆 matrix unitarity. We derive simplified expressions for factorizable short-distance interactions, 𝒦 3 , in two equivalent formalisms—one symmetric under particle interchange and one asymmetric. For the asymmetric case, we offer parametrizations useful for amplitude analysis. Finally, we examine toy models for 3⁢𝜋 systems at unphysically heavy pion masses with total isospins 0, 1, and 2.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2025

Measurement of the branching fraction, polarization, and time-dependent C P asymmetry in B 0 → ρ + ρ − decays and constraint on the CKM angle ϕ 2

We present a measurement of the branching fraction and fraction of longitudinal polarization of B 0 → ρ + ρ − decays, which have two π 0 ’s in the final state. We also measure time-dependent C P violation parameters for decays into longitudinally polarized ρ + ρ − pairs. This analysis is based on a data sample containing ( 387 ± 6 ) × 10 6 ϒ ( 4 S ) mesons collected with the Belle II detector at the SuperKEKB asymmetric-energy e + e − collider in 2019–2022. We obtain B ( B 0 → ρ + ρ − ) = ( 2.8 9 − 0.22 + 0.23 − 0.27 + 0.29 ) × 10 − 5 , f L = 0.92 1 − 0.025 + 0.024 − 0.015 + 0.017 , S = − 0.26 ± 0.19 ± 0.08 , and C = − 0.02 ± 0.1 2 − 0.05 + 0.06 , where the first uncertainties are statistical and the second are systematic. We use these results to perform an isospin analysis to constrain the Cabibbo-Kobayashi-Maskawa angle ϕ 2 and obtain two solutions; the result consistent with other Standard Model constraints is ϕ 2 = ( 92.6 − 4.7 + 4.5 ) ° . Published by the American Physical Society 2025

Adachi, I. (ORCID:0000000322870173)↗
DOE OSTI2025

Basis light-front quantization for the Λ b and Σ b baryons

Within the basis light-front quantization framework, we compute the masses and light-front wave functions of the Λ b baryon and its isospin triplet counterparts Σ b + , Σ b 0 , and Σ b − using a light-front effective Hamiltonian in the leading Fock sector. These wave functions are obtained as eigenstates of the effective Hamiltonian, which incorporates the one-gluon exchange interaction with fixed coupling and a three-dimensional confinement potential. With the quark masses and the couplings as adjustable parameters, the computed masses are set within the experimental range. The resulting predictions for their electromagnetic properties align well with other theoretical calculations. Additionally, the parton distribution functions (PDFs) of these baryons are obtained for the first time, with gluon and sea quark distributions dynamically generated through QCD evolution of the valence quark PDFs. Published by the American Physical Society 2025

Meng, Lingdi (ORCID:0009000096439904)↗
DOE OSTI2025

Systematic uncertainties from higher-twist corrections in DIS at large x

We investigate the systematic uncertainties and potential biases arising from the inclusion of large- x corrections to proton and deuteron deep inelastic scattering (DIS) data in global quantum chromodynamics (QCD) analyses. Using the CTEQ-JLab framework, we examine various approaches to implementing higher-twist corrections in nucleon structure functions and off-shell PDF modifications in deuteron targets. We analyze how these components interact and influence the determination of the d -quark PDF and the neutron structure function at large x . We find that it is very important to consider isospin-dependent higher-twist corrections in order to minimize implementation biases in the extracted quantities. Published by the American Physical Society 2025

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2025

Observation of D → K ¯ 1 ( 1270 ) μ + ν μ and test of lepton flavor universality with D → K ¯ 1 ( 1270 ) ℓ + ν ℓ

By analyzing 7.93 fb − 1 of e + e − collision data collected at the center-of-mass energy of 3.773 GeV with the BESIII detector operated at the BEPCII collider, we report the observation of the semimuonic decays of D + → K ¯ 1 ( 1270 ) 0 μ + ν μ and D 0 → K 1 ( 1270 ) − μ + ν μ with statistical significances of 12.5 σ and 6.0 σ , respectively. Their decay branching fractions are determined to be B [ D + → K ¯ 1 ( 1270 ) 0 μ + ν μ ] = ( 2.36 ± 0.2 0 − 0.27 + 0.18 ± 0.48 ) × 10 − 3 and B [ D 0 → K 1 ( 1270 ) − μ + ν μ ] = ( 0.78 ± 0.1 1 − 0.09 + 0.05 ± 0.15 ) × 10 − 3 , where the first and second uncertainties are statistical and systematic, respectively, and the third originates from the input branching fraction of K ¯ 1 ( 1270 ) 0 → K − π + π 0 or K 1 ( 1270 ) − → K − π + π − . Combining our branching fractions with the previous measurements of B [ D + → K ¯ 1 ( 1270 ) 0 e + ν e ] and B [ D 0 → K 1 ( 1270 ) − e + ν e ] , we determine the branching fraction ratios to be B [ D + → K ¯ 1 ( 1270 ) 0 μ + ν μ ] / B [ D + → K ¯ 1 ( 1270 ) 0 e + ν e ] = 1.03 ± 0.14 − 0.15 + 0.11 and B [ D 0 → K 1 ( 1270 ) − μ + ν μ ] / B [ D 0 → K 1 ( 1270 ) − e + ν e ] = 0.74 ± 0.13 − 0.13 + 0.08 . Using the branching fractions measured in this work and the world-average lifetimes of the D + and D 0 mesons, we determine the semimuonic partial decay width ratio to be Γ [ D + → K ¯ 1 ( 1270 ) 0 μ + ν μ ] / Γ [ D 0 → K 1 ( 1270 ) − μ + ν μ ] = 1.22 ± 0.10 − 0.09 + 0.06 , which is consistent with unity as predicted by isospin conservation. Published by the American Physical Society 2025

Ablikim, M.↗