Martina Cottini
Current Organizations / Institutes
The organizations/institutes from the scholar's latest article
Research Subjects
Martina Cottini has a total of 234 co-authors. Here are the top co-authors by number of shared publications:
- Gilberto Colangelo
Albert Einstein Center for Fundamental Physics, Institute for Theoretical Physics, University of Bern, Bern, Switzerland
5 shared publications - Jacobo Ruiz de Elvira
Universidad Complutense de Madrid
3 shared publications - Martin Hoferichter
Albert Einstein Center for Fundamental Physics, Institute for Theoretical Physics, University of Bern, Bern, Switzerland
3 shared publications - Simon Holz
University of Bern
3 shared publications - A. M. Lutz
IJCLab Université Paris-Saclay and CNRS/IN2P3 91405 Orsay France
1 shared publication - Achim Denig
Johannes Gutenberg University of Mainz
1 shared publication
Latest Publications
- Open Access
- 11 March 2026
- Published by American Physical Society (APS) in Physical Review Letters
- Vol. 136 (10) , 101903
Improved Calculation of Radiative Corrections to τ → π π ν τ Decays
A reliable calculation of radiative corrections to τ → π π ν τ decays is an important prerequisite for using hadronic τ decays for a data-driven evaluation of the hadronic-vacuum-polarization (HVP) contribution to the anomalous magnetic moment of the muon, a μ HVP , LO [ π π , τ ] . In this Letter, we present an improved model-independent analysis of these radiative corrections, including, for the first time, effects beyond pointlike pions in the evaluation of the loop diagrams. These structure-dependent corrections, implemented via a dispersive representation of the pion form factor, lead to significant changes compared to previous calculations due to enhancements near the ρ ( 770 ) resonance. We also devise strategies for the matching to chiral perturbation theory and a stable implementation of the real corrections down to the two-pion threshold, which shows that some higher-order isospin-breaking corrections need to be kept due to a strong threshold enhancement. Finally, we perform dispersive fits to the currently available τ → π π ν τ spectra and discuss the consequences for isospin-breaking corrections in the evaluation of a μ HVP , LO [ π π , τ ] .
- 11 March 2026
- Published by American Physical Society (APS) in Physical Review Letters
- Vol. 136 (10) , 101903
Open AccessImproved Calculation of Radiative Corrections to τ → π π ν τ Decays
A reliable calculation of radiative corrections to τ → π π ν τ decays is an important prerequisite for using hadronic τ decays for a data-driven evaluation of the hadronic-vacuum-polarization (HVP) contribution to the anomalous magnetic moment of the muon, a μ HVP , LO [ π π , τ ] . In this Letter, we present an improved model-independent analysis of these radiative corrections, including, for the first time, effects beyond pointlike pions in the evaluation of the loop diagrams. These structure-dependent corrections, implemented via a dispersive representation of the pion form factor, lead to significant changes compared to previous calculations due to enhancements near the ρ ( 770 ) resonance. We also devise strategies for the matching to chiral perturbation theory and a stable implementation of the real corrections down to the two-pion threshold, which shows that some higher-order isospin-breaking corrections need to be kept due to a strong threshold enhancement. Finally, we perform dispersive fits to the currently available τ → π π ν τ spectra and discuss the consequences for isospin-breaking corrections in the evaluation of a μ HVP , LO [ π π , τ ] .
- Open Access
- 17 February 2026
- Published by Springer Nature in Journal of High Energy Physics
- Vol. 2026 (2) , 181
Radiative corrections to τ → ππντ
A bstract: Hadronic τ decays present an opportunity to determine the isovector part of the hadronic-vacuum-polarization contribution to the anomalous magnetic moment of the muon in a way complementary to e + e − → hadrons cross sections. However, the required isospin rotation is only exact in the isospin limit, and corrections need to be under control to draw robust conclusions, most notably for τ → ππν τ decays to determine the two-pion contribution, $$ {a}_{\mu}^{\textrm{HVP},\textrm{LO}}\left[\pi \pi, \tau \right] $$ . In this work, we present a novel analysis of the required radiative corrections using dispersion relations, thereby extending in a model-independent way the previous analysis in chiral perturbation theory (ChPT) beyond the threshold region. In particular, we include the dominant structure-dependent virtual corrections from pion-pole diagrams, leading to sizable changes in the vicinity of the ρ (770) resonance. Moreover, we work out the matching to ChPT and devise a strategy for a stable numerical evaluation of real-emission contributions near the two-pion threshold, which proves important to capture isospin-breaking corrections enhanced by the threshold singularity. For the numerical analysis, we use a dispersive representation of the pion form factor including the ρ ′ , ρ ′′ resonances, perform fits to the available data sets for the τ → ππν τ spectral function, and calculate the corresponding radiative correction factor G EM ( s ) in a self-consistent manner. Based on these results, we evaluate the τ -specific isospin-breaking corrections to $$ {a}_{\mu}^{\textrm{HVP},\textrm{LO}}\left[\pi \pi, \tau \right] $$ .- 17 February 2026
- Published by Springer Nature in Journal of High Energy Physics
- Vol. 2026 (2) , 181
Open AccessRadiative corrections to τ → ππντ
A bstract: Hadronic τ decays present an opportunity to determine the isovector part of the hadronic-vacuum-polarization contribution to the anomalous magnetic moment of the muon in a way complementary to e + e − → hadrons cross sections. However, the required isospin rotation is only exact in the isospin limit, and corrections need to be under control to draw robust conclusions, most notably for τ → ππν τ decays to determine the two-pion contribution, $$ {a}_{\mu}^{\textrm{HVP},\textrm{LO}}\left[\pi \pi, \tau \right] $$ . In this work, we present a novel analysis of the required radiative corrections using dispersion relations, thereby extending in a model-independent way the previous analysis in chiral perturbation theory (ChPT) beyond the threshold region. In particular, we include the dominant structure-dependent virtual corrections from pion-pole diagrams, leading to sizable changes in the vicinity of the ρ (770) resonance. Moreover, we work out the matching to ChPT and devise a strategy for a stable numerical evaluation of real-emission contributions near the two-pion threshold, which proves important to capture isospin-breaking corrections enhanced by the threshold singularity. For the numerical analysis, we use a dispersive representation of the pion form factor including the ρ ′ , ρ ′′ resonances, perform fits to the available data sets for the τ → ππν τ spectral function, and calculate the corresponding radiative correction factor G EM ( s ) in a self-consistent manner. Based on these results, we evaluate the τ -specific isospin-breaking corrections to $$ {a}_{\mu}^{\textrm{HVP},\textrm{LO}}\left[\pi \pi, \tau \right] $$ . - Open Access
- 9 February 2026
- Published by Springer Nature in Journal of High Energy Physics
- Vol. 2026 (2) , 98
Isospin-breaking in the ππ scattering amplitude. Part I. Effects due to the pion mass difference
A bstract: This is the first of a series of papers devoted to a detailed analysis of isospin-breaking effects in the ππ scattering amplitude and the vector form factor of the pion. Isospin breaking originates from the mass difference between up and down quarks and from electromagnetic effects. The latter can be further split into effects due to the pion-mass difference and the remaining virtual and real photonic effects. In this paper, we derive the modifications to the Roy equations for ππ scattering due to the mass difference between the charged and the neutral pion. We solve the equations numerically after matching them to the chiral representation of the ππ scattering amplitude evaluated in the same approximation, which is also provided. Numerical results are presented and discussed in detail.
- 9 February 2026
- Published by Springer Nature in Journal of High Energy Physics
- Vol. 2026 (2) , 98
Open AccessIsospin-breaking in the ππ scattering amplitude. Part I. Effects due to the pion mass difference
A bstract: This is the first of a series of papers devoted to a detailed analysis of isospin-breaking effects in the ππ scattering amplitude and the vector form factor of the pion. Isospin breaking originates from the mass difference between up and down quarks and from electromagnetic effects. The latter can be further split into effects due to the pion-mass difference and the remaining virtual and real photonic effects. In this paper, we derive the modifications to the Roy equations for ππ scattering due to the mass difference between the charged and the neutral pion. We solve the equations numerically after matching them to the chiral representation of the ππ scattering amplitude evaluated in the same approximation, which is also provided. Numerical results are presented and discussed in detail.
- Open AccessIsospin-breaking in the $ππ$ scattering amplitude I: Effects due to the pion mass differenceThis is the first of a series of papers devoted to a detailed analysis of isospin-breaking effects in the $ππ$ scattering amplitude and the vector form factor of the pion. Isospin breaking originates from the mass difference between up and down quarks and from electromagnetic effects. The latter can be further split into effects due to the pion-mass difference and the remaining virtual and real photonic effects. In this paper, we derive the modifications to the Roy equations for $ππ$ scattering due to the mass difference between the charged and the neutral pion. We solve the equations numerically after matching them to the chiral representation of the $ππ$ scattering amplitude evaluated in the same approximation, which is also provided. Numerical results are presented and discussed in detail.Open AccessIsospin-breaking in the $ππ$ scattering amplitude I: Effects due to the pion mass differenceThis is the first of a series of papers devoted to a detailed analysis of isospin-breaking effects in the $ππ$ scattering amplitude and the vector form factor of the pion. Isospin breaking originates from the mass difference between up and down quarks and from electromagnetic effects. The latter can be further split into effects due to the pion-mass difference and the remaining virtual and real photonic effects. In this paper, we derive the modifications to the Roy equations for $ππ$ scattering due to the mass difference between the charged and the neutral pion. We solve the equations numerically after matching them to the chiral representation of the $ππ$ scattering amplitude evaluated in the same approximation, which is also provided. Numerical results are presented and discussed in detail.
- Top Cited PapersOpen Access
- 10 September 2025
- Published by Elsevier in Physics Reports
- Vol. 1143, 1-158
The anomalous magnetic moment of the muon in the Standard Model: an update
- 10 September 2025
- Published by Elsevier in Physics Reports
- Vol. 1143, 1-158
Top Cited PapersOpen AccessThe anomalous magnetic moment of the muon in the Standard Model: an update