Kaon radiative leptonic decay rates from lattice QCD simulations at the physical point
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| Autores principales: | , , , , , , , , |
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2025
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| author | Di Palma, R. Frezzotti, R. Gagliardi, G. Lubicz, V. Martinelli, G. Sachrajda, C. T. Sanfilippo, F. Simula, S. Tantalo, N. |
| author_facet | Di Palma, R. Frezzotti, R. Gagliardi, G. Lubicz, V. Martinelli, G. Sachrajda, C. T. Sanfilippo, F. Simula, S. Tantalo, N. |
| contents | We present a lattice QCD calculation of the radiative leptonic decay rates of the kaon, improving upon our previous work, arXiv:2006.05358. Our analysis uses gauge ensembles generated by the Extended Twisted Mass Collaboration (ETMC) with $N_{f} = 2 + 1 + 1$ flavors of Wilson-clover twisted mass fermions. For the first time, we go beyond the electroquenched approximation by including quark-disconnected contributions. Several key improvements have been implemented: (i) the simulations are now performed directly at physical light- and strange-quark masses, (ii) finite-size effects are carefully investigated using lattices with spatial extents ranging from $L \simeq 3.8\,\mathrm{fm}$ to $L \simeq 7.7\,\mathrm{fm}$, and (iii) the continuum extrapolation is based on three lattice spacings in the range $a \in [0.08, 0.058]\,\mathrm{fm}$. As a result of the high-precision determination of the relevant correlation functions, we reduce the uncertainties on both the axial and vector form factors by nearly a factor of two compared to our previous analysis. When compared to experimental measurements in the electron channel ($K^- \to e^- \barν_e γ$), our results show a tension -- at the level of $2.6$ standard deviations -- with respect to KLOE data. On the other hand, they are compatible with measurements from the E36 Collaboration at J-PARC. In the muonic decay channel ($K^- \to μ^- \barν_μγ$), we confirm the tensions, already observed in our previous study, between lattice QCD predictions and ISTRA+ and OKA data, which are both primarily sensitive to the value of the negative-helicity form factor $F^{-}$. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2504_08680 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Kaon radiative leptonic decay rates from lattice QCD simulations at the physical point Di Palma, R. Frezzotti, R. Gagliardi, G. Lubicz, V. Martinelli, G. Sachrajda, C. T. Sanfilippo, F. Simula, S. Tantalo, N. High Energy Physics - Lattice High Energy Physics - Phenomenology We present a lattice QCD calculation of the radiative leptonic decay rates of the kaon, improving upon our previous work, arXiv:2006.05358. Our analysis uses gauge ensembles generated by the Extended Twisted Mass Collaboration (ETMC) with $N_{f} = 2 + 1 + 1$ flavors of Wilson-clover twisted mass fermions. For the first time, we go beyond the electroquenched approximation by including quark-disconnected contributions. Several key improvements have been implemented: (i) the simulations are now performed directly at physical light- and strange-quark masses, (ii) finite-size effects are carefully investigated using lattices with spatial extents ranging from $L \simeq 3.8\,\mathrm{fm}$ to $L \simeq 7.7\,\mathrm{fm}$, and (iii) the continuum extrapolation is based on three lattice spacings in the range $a \in [0.08, 0.058]\,\mathrm{fm}$. As a result of the high-precision determination of the relevant correlation functions, we reduce the uncertainties on both the axial and vector form factors by nearly a factor of two compared to our previous analysis. When compared to experimental measurements in the electron channel ($K^- \to e^- \barν_e γ$), our results show a tension -- at the level of $2.6$ standard deviations -- with respect to KLOE data. On the other hand, they are compatible with measurements from the E36 Collaboration at J-PARC. In the muonic decay channel ($K^- \to μ^- \barν_μγ$), we confirm the tensions, already observed in our previous study, between lattice QCD predictions and ISTRA+ and OKA data, which are both primarily sensitive to the value of the negative-helicity form factor $F^{-}$. |
| title | Kaon radiative leptonic decay rates from lattice QCD simulations at the physical point |
| topic | High Energy Physics - Lattice High Energy Physics - Phenomenology |
| url | https://arxiv.org/abs/2504.08680 |