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The European physical journal / C 80(2), 81 (1-55) (2020). doi:10.1140/epjc/s10052-020-7611-9, Previous studies have shown that the Hidden Local Symmetry (HLS) Model, supplied with appropriate symmetry breaking mechanisms, provides an Effective Lagrangian (BHLS) able to encompass a large number of processes within a unified framework. This allowed one to design a global fit procedure which provides a fair simultaneous description of the $e^+ e^-$ annihilation into six final states ($\pi ^+\pi ^-$, $\pi ^0\gamma $, $\eta \gamma $, $\pi ^+\pi ^-\pi ^0$, $K^+K^-$, $K_L K_S$), the dipion spectrum in the $\tau $ decay and some more light meson decay partial widths. In this paper, additional breaking schemes are defined which improve the BHLS working and extend its scope so as to absorb spacelike processes within a new framework (${\hbox {BHLS}}_2$). The phenomenology previously explored with BHLS is fully revisited in the ${\hbox {BHLS}}_2$ context with special emphasis on the $\phi $ mass region using all available data samples. It is shown that ${\hbox {BHLS}}_2$ addresses perfectly the close spacelike region covered by NA7 and Fermilab data; it is also shown that the recent lattice QCD (LQCD) information on the pion form factor are accurately predicted by the ${\hbox {BHLS}}_2$ fit functions derived from fits to only annihilation data. The contribution to the muon anomalous magnetic moment $a_\mu ^{\mathrm{th}}$ of these annihilation channels over the range of validity of ${\hbox {BHLS}}_2$ (up to $\simeq $ 1.05 GeV) is updated within the new ${\hbox {BHLS}}_2$ framework and shown to strongly reduce the former BHLS systematics. The uncertainty on $a_\mu ^{\mathrm{th}}(\sqrt{s}< 1.05 \, \hbox {GeV}$) is much improved compared to standard approaches relying on direct integration methods of measured spectra. Using the ${\hbox {BHLS}}_2$ results, the leading-order HVP contribution to the muon anomalous moment is $a_\mu ^{\mathrm{HVP-LO}}= 686.65 \pm 3.01 +(+1.16,-0.75)_{\mathrm{syst}}$ in units of $10^{-10}$. Using a conservative estimate for the light-by-light contribution, our evaluation for the muon anomalous magnetic moment is $a_\mu ^{\mathrm{th}}=\left[ 11\,659\,175.96 \pm 4.17 +(+1.16,-0.75)_{\mathrm{syst}}\right] \times 10^{-10}$. The relationship between the dispersive and LQCD approaches to the $\rho ^0$–$\gamma $ mixing is also discussed which may amount to a shift of $\delta a_\mu [\pi \pi ]_{\rho \gamma }=+(3.10\pm 0.31) \times 10^{-10}$ at LO+NLO, presently treated as additional systematics. Taking also this shift into account, the difference $a_\mu ^{\mathrm{th}}-a_\mu ^{\mathrm{BNL}}$ exhibits a significance not smaller than $3.8 \sigma $., Published by Springer, Heidelberg

The European physical journal / C 80(3), 244 (1) (2020). doi:10.1140/epjc/s10052-020-7724-1, Previous studies have shown that the Hidden Local Symmetry (HLS) Model, supplied with appropriate symmetry breaking mechanisms, provides an Effective Lagrangian (BHLS) able to encompass a large number of processes within a unified framework. This allowed one to design a global fit procedure which provides a fair simultaneous description of the $e^+ e^-$ annihilation into six final states ($\pi ^+\pi ^-$, $\pi ^0\gamma $, $\eta \gamma $, $\pi ^+\pi ^-\pi ^0$, $K^+K^-$, $K_L K_S$), the dipion spectrum in the $\tau $ decay and some more light meson decay partial widths. In this paper, additional breaking schemes are defined which improve the BHLS working and extend its scope so as to absorb spacelike processes within a new framework (${\hbox {BHLS}}_2$). The phenomenology previously explored with BHLS is fully revisited in the ${\hbox {BHLS}}_2$ context with special emphasis on the $\phi $ mass region using all available data samples. It is shown that ${\hbox {BHLS}}_2$ addresses perfectly the close spacelike region covered by NA7 and Fermilab data; it is also shown that the recent lattice QCD (LQCD) information on the pion form factor are accurately predicted by the ${\hbox {BHLS}}_2$ fit functions derived from fits to only annihilation data. The contribution to the muon anomalous magnetic moment $a_\mu ^{\mathrm{th}}$ of these annihilation channels over the range of validity of ${\hbox {BHLS}}_2$ (up to $\simeq $ 1.05 GeV) is updated within the new ${\hbox {BHLS}}_2$ framework and shown to strongly reduce the former BHLS systematics. The uncertainty on $a_\mu ^{\mathrm{th}}(\sqrt{s}< 1.05 \, \hbox {GeV}$) is much improved compared to standard approaches relying on direct integration methods of measured spectra. Using the ${\hbox {BHLS}}_2$ results, the leading-order HVP contribution to the muon anomalous moment is $a_\mu ^{\mathrm{HVP-LO}}= 686.65 \pm 3.01 +(+1.16,-0.75)_{\mathrm{syst}}$ in units of $10^{-10}$. Using a conservative estimate for the light-by-light contribution, our evaluation for the muon anomalous magnetic moment is $a_\mu ^{\mathrm{th}}=\left[ 11\,659\,175.96 \pm 4.17 +(+1.16,-0.75)_{\mathrm{syst}}\right] \times 10^{-10}$. The relationship between the dispersive and LQCD approaches to the $\rho ^0$–$\gamma $ mixing is also discussed which may amount to a shift of $\delta a_\mu [\pi \pi ]_{\rho \gamma }=+(3.10\pm 0.31) \times 10^{-10}$ at LO+NLO, presently treated as additional systematics. Taking also this shift into account, the difference $a_\mu ^{\mathrm{th}}-a_\mu ^{\mathrm{BNL}}$ exhibits a significance not smaller than $3.8 \sigma $., Published by Springer, Heidelberg

This contribution about amplitude analyses in multibody hadronic charm decays deals with some attempts to introduce theoretical constraints. Different effective hadronic formalism approaches are mentioned. A recent work, based on a basic weak interaction process and a Chiral unitary model to account for the final state interaction, is described in details for the $f_0(980)$ production in $D_s^+ \to \pi^+ \pi^+ \pi^-$ and $D_s^+ \to \pi^+ K^+ K^- $ decays. Within the framework of the diagrammatic approach and flavor symmetry, a global analysis of two-body $D$ decays into a vector meson and a pseudoscalar meson is presented. A quasi-two-body QCD factorization model for $D$ decays into three mesons and its recent application to $D^0 \to K_S^0 \pi^+ \pi^-$ is outlined. For processes with final-state pions and kaons and as an alternative to the sum of Breit-Wigner amplitudes, often used in experimental Dalitz-plot analyses, amplitude parametrizations, in term of unitary $\pi \pi$, $\pi K$ and $K \bar K$ form factors, are proposed. These parametrizations are derived from quasi-two-body factorization models., Comment: 12 pages, 1 table, 2 figures, Contribution to the VIII International Workshop On Charm Physics, 5-9 September, 2016, Bologna, Italy. A related work, Ref. [18], has been added in section 2.1 and commented

(1977). doi:10.1016/0370-2693(77)90417-8, We present the first data on the inclusive structure function for π 0 -electroproduction. The data are compared to charged pion electroproduction and charged pion production from electron-positron annihilation taking the quark-parton model as a guide.

(1979). doi:10.1103/PhysRevD.19.2070, Quantum chromodynamics has placed the problem of hadronic symmetry breaking on a rational basis. The current-quark mass ratios can be shown to be renormalization-group invariants up to small and controllable corrections from flavor interactions. We calculate the mass ratios of the light u, d, and s quarks using the pseudoscalar-meson mass spectrum, the baryon mass spectrum, and the η→3π decay. The main theoretical assumptions are that low-lying-resonance and Born terms correctly estimate the photonic contribution to isotopic mass splitting and that chiral perturbation theory—equivalently kaon partial convervation of axialvector current—correctly estimates chiral-symmetry breaking. Taking account of all leading-order chiral corrections to the meson spectrum and from the baryon spectrum and η→3π decay we obtain mumd=0.38±0.13 and mdms=0.045±0.011. We conclude that while a vanishing up-quark mass is not rigorously ruled out it is unattractive from the standpoint of the presently consistent phenomenology of hadronic symmetry breaking.

21 pp. (1978)., Decays of the heavy lepton τ have now been observed in e+e− ‐ collisions at the energy of the ψ′‐resonace, which results in an improved mass determination Mτ=1.807±0.020 GeV. For the τ‐life‐time a new upper limit of ττ?3.5⋅10−12 sec. is given. The evidence for the decay τ→νπρ has been strengthened, and the πρ‐system is found to be in an S‐wave state with JP=1+, proving the axial vector component in the leptonic coupling of the τ to hadrons. The branching ratio is given with BR(τ−→νπ−ρ0) =0.050±0.015. The total hadronic cross section agrees within errors with the quarksum rule including QCD‐corrections. The production and decay distributions of the decay J/ψ→f0γ have been measured and found to agree well with a QCD calculation based on the exchange of two gluons.

Baryon resonance production in proton-proton collisions at a kinetic beam energy of 1.25 GeV is investigated. The multi-differential data were measured by the HADES collaboration. Exclusive channels with one pion in the final state ($np\pi^{+}$ and $pp\pi^{0}$) were put to extended studies based on various observables in the framework of a one-pion exchange model and with solutions obtained within the framework of a partial wave analysis (PWA) of the Bonn-Gatchina group. The results of the PWA confirm the dominant contribution of the $\Delta$(1232), yet with a sizable impact of the $N$(1440) and non-resonant partial waves., Comment: 12 pages, 6 figures