The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
S Pacetti - One of the best experts on this subject based on the ideXlab platform.
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the cross section of e e rightarrow lambda overline sigma 0 text c c as a litmus test of isospin violation in the decays of vector charmonia into lambda overline sigma 0 text c c
European Physical Journal C, 2020Co-Authors: Rinaldo Baldini Ferroli, Alessio Mangoni, S PacettiAbstract:Under the aegis of isospin conservation, the amplitudes in Born approximation, i.e., considering the only one-photon-exchange mechanism, of the decay $$\psi \rightarrow \Lambda \overline{\Sigma }{}^0+\text {c.c.}$$ , where $$\psi $$ is a vector charmonium, and of the reaction $$e^+e^-\rightarrow \Lambda \overline{\Sigma }{}^0+\text {c.c.}$$ at the $$\psi $$ mass, are parametrized by the same Electromagnetic Coupling. It follows that, the modulus of such a Coupling can be extracted from the data on the two observables: the decay branching fraction and the annihilation cross section. By considering the first two vector charmonia, $$J/\psi $$ and $$\psi (2S)$$ , it is found that, especially in the case of $$\psi (2S)$$ , there is a substantial discrepancy between the values of the modulus of the same Electromagnetic Coupling extracted from the branching ratio and the cross section. We propose, as a possible explanation for such a disagreement, the presence in the decay amplitude of isospin-violating contributions driven by two different mechanisms, that, however, appear to be more favored in the $$\psi (2S)$$ than in the $$J/\psi $$ decays.
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the cross section of e e to lambda overline sigma 0 rm c c as a litmus test of isospin violation in the decays of vector charmonia into lambda overline sigma 0 rm c c
arXiv: High Energy Physics - Phenomenology, 2020Co-Authors: Rinaldo Baldini Ferroli, Alessio Mangoni, S PacettiAbstract:Under the aegis of isospin conservation, the amplitudes in Born approximation, i.e., considering the only one-photon-exchange mechanism, of the decay $\psi\to \Lambda \overline \Sigma{}^0+{\rm c.c.}$, where $\psi$ is a vector charmonium, and of the reaction $e^+e^- \to \Lambda \overline \Sigma{}^0+{\rm c.c.}$ at the $\psi$ mass, are parametrized by the same Electromagnetic Coupling. It follows that, the modulus of such a Coupling can be extracted the data on the two observables: the decay branching fraction and the annihilation cross section. By considering the first two vector charmonia, $J/\psi$ and $\psi(2S)$, it is found that, especially in the case of $\psi(2S)$, there is a substantial discrepancy between the values of the modulus of the same Electromagnetic Coupling extracted from the branching ratio and the cross section. We propose, as a possible explanation for such a disagreement, the presence in the decay amplitude of an isospin-violating contribution driven by a mechanism based on physical (on-shell) intermediate states, that, due to their own nature, should be more effective in the $\psi(2S)$ decay than in that of the $J/\psi$.
Rinaldo Baldini Ferroli - One of the best experts on this subject based on the ideXlab platform.
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the cross section of e e rightarrow lambda overline sigma 0 text c c as a litmus test of isospin violation in the decays of vector charmonia into lambda overline sigma 0 text c c
European Physical Journal C, 2020Co-Authors: Rinaldo Baldini Ferroli, Alessio Mangoni, S PacettiAbstract:Under the aegis of isospin conservation, the amplitudes in Born approximation, i.e., considering the only one-photon-exchange mechanism, of the decay $$\psi \rightarrow \Lambda \overline{\Sigma }{}^0+\text {c.c.}$$ , where $$\psi $$ is a vector charmonium, and of the reaction $$e^+e^-\rightarrow \Lambda \overline{\Sigma }{}^0+\text {c.c.}$$ at the $$\psi $$ mass, are parametrized by the same Electromagnetic Coupling. It follows that, the modulus of such a Coupling can be extracted from the data on the two observables: the decay branching fraction and the annihilation cross section. By considering the first two vector charmonia, $$J/\psi $$ and $$\psi (2S)$$ , it is found that, especially in the case of $$\psi (2S)$$ , there is a substantial discrepancy between the values of the modulus of the same Electromagnetic Coupling extracted from the branching ratio and the cross section. We propose, as a possible explanation for such a disagreement, the presence in the decay amplitude of isospin-violating contributions driven by two different mechanisms, that, however, appear to be more favored in the $$\psi (2S)$$ than in the $$J/\psi $$ decays.
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the cross section of e e to lambda overline sigma 0 rm c c as a litmus test of isospin violation in the decays of vector charmonia into lambda overline sigma 0 rm c c
arXiv: High Energy Physics - Phenomenology, 2020Co-Authors: Rinaldo Baldini Ferroli, Alessio Mangoni, S PacettiAbstract:Under the aegis of isospin conservation, the amplitudes in Born approximation, i.e., considering the only one-photon-exchange mechanism, of the decay $\psi\to \Lambda \overline \Sigma{}^0+{\rm c.c.}$, where $\psi$ is a vector charmonium, and of the reaction $e^+e^- \to \Lambda \overline \Sigma{}^0+{\rm c.c.}$ at the $\psi$ mass, are parametrized by the same Electromagnetic Coupling. It follows that, the modulus of such a Coupling can be extracted the data on the two observables: the decay branching fraction and the annihilation cross section. By considering the first two vector charmonia, $J/\psi$ and $\psi(2S)$, it is found that, especially in the case of $\psi(2S)$, there is a substantial discrepancy between the values of the modulus of the same Electromagnetic Coupling extracted from the branching ratio and the cross section. We propose, as a possible explanation for such a disagreement, the presence in the decay amplitude of an isospin-violating contribution driven by a mechanism based on physical (on-shell) intermediate states, that, due to their own nature, should be more effective in the $\psi(2S)$ decay than in that of the $J/\psi$.
Zhiqing Zhang - One of the best experts on this subject based on the ideXlab platform.
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reevaluation of the hadronic vacuum polarisation contributions to the standard model predictions of the muon g 2 and alpha mz using newest hadronic cross section data
arXiv: High Energy Physics - Phenomenology, 2017Co-Authors: M Davier, Andreas Hoecker, Bogdan Malaescu, Zhiqing ZhangAbstract:We reevaluate the hadronic vacuum polarisation contributions to the muon magnetic anomaly and to the running of the Electromagnetic Coupling constant at the Z-boson mass. We include newest e+e- to hadrons cross-section data (among others) from the BABAR and VEPP-2000 experiments. For the muon (g-2)/2 we find for the lowest-order hadronic contribution (693.1 +- 3.4) 10^-10, improving the precision of our previous evaluation by 21%. The full Standard Model prediction differs by 3.5 sigma from the experimental value. The five-quark hadronic contribution to alpha(mZ) is evaluated to be (276.0 +- 0.9) 10^-4.
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reevaluation of the hadronic vacuum polarisation contributions to the standard model predictions of the muon g 2 and alpha m_z 2 using newest hadronic cross section data
European Physical Journal C, 2017Co-Authors: M Davier, Andreas Hoecker, Bogdan Malaescu, Zhiqing ZhangAbstract:We reevaluate the hadronic vacuum polarisation contributions to the muon magnetic anomaly and to the running of the Electromagnetic Coupling constant at the Z-boson mass. We include newest \(e^+e^- \rightarrow \mathrm{hadrons}\) cross-section data (among others) from the BABAR and VEPP-2000 experiments. For the muon \((g-2)/2\) we find for the lowest-order hadronic contribution \((693.1 \pm 3.4)\times 10^{-10}\), improving the precision of our previous evaluation by 21%. The full Standard Model prediction differs by \(3.5\,\sigma \) from the experimental value. The five-quark hadronic contribution to \(\alpha (m_Z^2)\) is evaluated to be \((276.0\pm 0.9)\times 10^{-4}\).
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reevaluation of the hadronic contributions to the muon g 2 and to alpha m 2 _ z
European Physical Journal C, 2011Co-Authors: M Davier, Andreas Hoecker, Bogdan Malaescu, Zhiqing ZhangAbstract:We reevaluate the hadronic contributions to the muon magnetic anomaly, and to the running of the Electromagnetic Coupling constant at the Z-boson mass. We include new π+π− cross-section data from KLOE, all available multi-hadron data from BABAR, a reestimation of missing low-energy contributions using results on cross sections and process dynamics from BABAR, a reevaluation of all experimental contributions using the software package HVPTools together with a reanalysis of inter-experiment and inter-channel correlations, and a reevaluation of the continuum contributions from perturbative QCD at four loops. These improvements lead to a decrease in the hadronic contributions with respect to earlier evaluations. For the muon g−2 we find lowest-order hadronic contributions of (692.3±4.2)⋅10−10 and (701.5±4.7)⋅10−10 for the e+e−-based and τ-based analyses, respectively, and full Standard Model predictions that differ by 3.6σ and 2.4σ from the experimental value. For the e+e−-based five-quark hadronic contribution to \(\alpha(M_{Z}^{2})\) we find \(\varDelta \alpha_{\mathrm{had}}^{(5)}(M_{Z}^{2}) =(274.9\pm1.0)\cdot10^{-4}\). The reduced Electromagnetic Coupling strength at MZ leads to an increase by 12 GeV in the central value of the Higgs boson mass obtained by the standard Gfitter fit to electroweak precision data.
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reevaluation of the hadronic contributions to the muon g 2 and to alpha mz
arXiv: High Energy Physics - Phenomenology, 2010Co-Authors: M Davier, Andreas Hoecker, Bogdan Malaescu, Zhiqing ZhangAbstract:We reevaluate the hadronic contributions to the muon magnetic anomaly, and to the running of the Electromagnetic Coupling constant at the Z-boson mass. We include new pi+pi- cross-section data from KLOE, all available multi-hadron data from BABAR, a reestimation of missing low-energy contributions using results on cross sections and process dynamics from BABAR, a reevaluation of all experimental contributions using the software package HVPTools, together with a reanalysis of inter-experiment and inter-channel correlations, and a reevaluation of the continuum contributions from perturbative QCD at four loops. These improvements lead to a decrease in the hadronic contributions with respect to earlier evaluations. For the muon g-2 we find lowest-order hadronic contributions of (692.3 +- 4.2) 10^-10 and (701.5 +- 4.7) 10^-10 for the e+e- based and tau-based analyses, respectively, and full Standard Model predictions that differ by 3.6 sigma and 2.4 sigma from the experimental value. For the e+e- based five-quark hadronic contribution to alpha(MZ) we find Delta_alpha_had[5](MZ)=(275.7 +- 1.0) 10^-4. The reduced Electromagnetic Coupling strength at MZ leads to an increase by 7 GeV in the most probable Higgs boson mass obtained by the standard Gfitter fit to electroweak precision data.
Alessio Mangoni - One of the best experts on this subject based on the ideXlab platform.
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the cross section of e e rightarrow lambda overline sigma 0 text c c as a litmus test of isospin violation in the decays of vector charmonia into lambda overline sigma 0 text c c
European Physical Journal C, 2020Co-Authors: Rinaldo Baldini Ferroli, Alessio Mangoni, S PacettiAbstract:Under the aegis of isospin conservation, the amplitudes in Born approximation, i.e., considering the only one-photon-exchange mechanism, of the decay $$\psi \rightarrow \Lambda \overline{\Sigma }{}^0+\text {c.c.}$$ , where $$\psi $$ is a vector charmonium, and of the reaction $$e^+e^-\rightarrow \Lambda \overline{\Sigma }{}^0+\text {c.c.}$$ at the $$\psi $$ mass, are parametrized by the same Electromagnetic Coupling. It follows that, the modulus of such a Coupling can be extracted from the data on the two observables: the decay branching fraction and the annihilation cross section. By considering the first two vector charmonia, $$J/\psi $$ and $$\psi (2S)$$ , it is found that, especially in the case of $$\psi (2S)$$ , there is a substantial discrepancy between the values of the modulus of the same Electromagnetic Coupling extracted from the branching ratio and the cross section. We propose, as a possible explanation for such a disagreement, the presence in the decay amplitude of isospin-violating contributions driven by two different mechanisms, that, however, appear to be more favored in the $$\psi (2S)$$ than in the $$J/\psi $$ decays.
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the cross section of e e to lambda overline sigma 0 rm c c as a litmus test of isospin violation in the decays of vector charmonia into lambda overline sigma 0 rm c c
arXiv: High Energy Physics - Phenomenology, 2020Co-Authors: Rinaldo Baldini Ferroli, Alessio Mangoni, S PacettiAbstract:Under the aegis of isospin conservation, the amplitudes in Born approximation, i.e., considering the only one-photon-exchange mechanism, of the decay $\psi\to \Lambda \overline \Sigma{}^0+{\rm c.c.}$, where $\psi$ is a vector charmonium, and of the reaction $e^+e^- \to \Lambda \overline \Sigma{}^0+{\rm c.c.}$ at the $\psi$ mass, are parametrized by the same Electromagnetic Coupling. It follows that, the modulus of such a Coupling can be extracted the data on the two observables: the decay branching fraction and the annihilation cross section. By considering the first two vector charmonia, $J/\psi$ and $\psi(2S)$, it is found that, especially in the case of $\psi(2S)$, there is a substantial discrepancy between the values of the modulus of the same Electromagnetic Coupling extracted from the branching ratio and the cross section. We propose, as a possible explanation for such a disagreement, the presence in the decay amplitude of an isospin-violating contribution driven by a mechanism based on physical (on-shell) intermediate states, that, due to their own nature, should be more effective in the $\psi(2S)$ decay than in that of the $J/\psi$.
M Davier - One of the best experts on this subject based on the ideXlab platform.
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reevaluation of the hadronic vacuum polarisation contributions to the standard model predictions of the muon g 2 and alpha mz using newest hadronic cross section data
arXiv: High Energy Physics - Phenomenology, 2017Co-Authors: M Davier, Andreas Hoecker, Bogdan Malaescu, Zhiqing ZhangAbstract:We reevaluate the hadronic vacuum polarisation contributions to the muon magnetic anomaly and to the running of the Electromagnetic Coupling constant at the Z-boson mass. We include newest e+e- to hadrons cross-section data (among others) from the BABAR and VEPP-2000 experiments. For the muon (g-2)/2 we find for the lowest-order hadronic contribution (693.1 +- 3.4) 10^-10, improving the precision of our previous evaluation by 21%. The full Standard Model prediction differs by 3.5 sigma from the experimental value. The five-quark hadronic contribution to alpha(mZ) is evaluated to be (276.0 +- 0.9) 10^-4.
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reevaluation of the hadronic vacuum polarisation contributions to the standard model predictions of the muon g 2 and alpha m_z 2 using newest hadronic cross section data
European Physical Journal C, 2017Co-Authors: M Davier, Andreas Hoecker, Bogdan Malaescu, Zhiqing ZhangAbstract:We reevaluate the hadronic vacuum polarisation contributions to the muon magnetic anomaly and to the running of the Electromagnetic Coupling constant at the Z-boson mass. We include newest \(e^+e^- \rightarrow \mathrm{hadrons}\) cross-section data (among others) from the BABAR and VEPP-2000 experiments. For the muon \((g-2)/2\) we find for the lowest-order hadronic contribution \((693.1 \pm 3.4)\times 10^{-10}\), improving the precision of our previous evaluation by 21%. The full Standard Model prediction differs by \(3.5\,\sigma \) from the experimental value. The five-quark hadronic contribution to \(\alpha (m_Z^2)\) is evaluated to be \((276.0\pm 0.9)\times 10^{-4}\).
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reevaluation of the hadronic contributions to the muon g 2 and to alpha m 2 _ z
European Physical Journal C, 2011Co-Authors: M Davier, Andreas Hoecker, Bogdan Malaescu, Zhiqing ZhangAbstract:We reevaluate the hadronic contributions to the muon magnetic anomaly, and to the running of the Electromagnetic Coupling constant at the Z-boson mass. We include new π+π− cross-section data from KLOE, all available multi-hadron data from BABAR, a reestimation of missing low-energy contributions using results on cross sections and process dynamics from BABAR, a reevaluation of all experimental contributions using the software package HVPTools together with a reanalysis of inter-experiment and inter-channel correlations, and a reevaluation of the continuum contributions from perturbative QCD at four loops. These improvements lead to a decrease in the hadronic contributions with respect to earlier evaluations. For the muon g−2 we find lowest-order hadronic contributions of (692.3±4.2)⋅10−10 and (701.5±4.7)⋅10−10 for the e+e−-based and τ-based analyses, respectively, and full Standard Model predictions that differ by 3.6σ and 2.4σ from the experimental value. For the e+e−-based five-quark hadronic contribution to \(\alpha(M_{Z}^{2})\) we find \(\varDelta \alpha_{\mathrm{had}}^{(5)}(M_{Z}^{2}) =(274.9\pm1.0)\cdot10^{-4}\). The reduced Electromagnetic Coupling strength at MZ leads to an increase by 12 GeV in the central value of the Higgs boson mass obtained by the standard Gfitter fit to electroweak precision data.
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reevaluation of the hadronic contributions to the muon g 2 and to alpha mz
arXiv: High Energy Physics - Phenomenology, 2010Co-Authors: M Davier, Andreas Hoecker, Bogdan Malaescu, Zhiqing ZhangAbstract:We reevaluate the hadronic contributions to the muon magnetic anomaly, and to the running of the Electromagnetic Coupling constant at the Z-boson mass. We include new pi+pi- cross-section data from KLOE, all available multi-hadron data from BABAR, a reestimation of missing low-energy contributions using results on cross sections and process dynamics from BABAR, a reevaluation of all experimental contributions using the software package HVPTools, together with a reanalysis of inter-experiment and inter-channel correlations, and a reevaluation of the continuum contributions from perturbative QCD at four loops. These improvements lead to a decrease in the hadronic contributions with respect to earlier evaluations. For the muon g-2 we find lowest-order hadronic contributions of (692.3 +- 4.2) 10^-10 and (701.5 +- 4.7) 10^-10 for the e+e- based and tau-based analyses, respectively, and full Standard Model predictions that differ by 3.6 sigma and 2.4 sigma from the experimental value. For the e+e- based five-quark hadronic contribution to alpha(MZ) we find Delta_alpha_had[5](MZ)=(275.7 +- 1.0) 10^-4. The reduced Electromagnetic Coupling strength at MZ leads to an increase by 7 GeV in the most probable Higgs boson mass obtained by the standard Gfitter fit to electroweak precision data.