Impact of the $a_1(1260) π$ cascade contribution on $D^0 \to π^+ π^- \ell^+ \ell^-$ decays
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| Format: | Preprint |
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2025
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| _version_ | 1866918186333503488 |
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| author | Solomonidi, Eleftheria Silva, Luiz Vale |
| author_facet | Solomonidi, Eleftheria Silva, Luiz Vale |
| contents | We revisit the Standard Model description of the recently measured rare decays $D^0\toπ^+π^-\ell^+\ell^-$. Because of the effectiveness of the Glashow-Iliopoulos-Maiani mechanism in charm flavour-changing neutral currents, those decays are driven by non-local insertions of four-quark operators. Following previous work, we consider the mediation of resonances both for the dipion and dilepton pairs. For the first time, we incorporate the effect of the cascade-type topology $D^0\to π^- a_1^+(1260)(\toπ^+ρ^0(\to\ell^+\ell^-))$, which manifests distinctly in the invariant-mass and angular distributions. We find that this partial amplitude comprises one of the largest contributions to the decay rate and obtain an unprecedented agreement of the Standard Model prediction with the available LHCb data. Finally, we compare to the available CLEO-c, LHCb, and BESIII amplitude analyses for the analogous four-body hadronic decays and find that similar values of the hadronic parameters of our model successfully describe the two classes of decays. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2511_02775 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Impact of the $a_1(1260) π$ cascade contribution on $D^0 \to π^+ π^- \ell^+ \ell^-$ decays Solomonidi, Eleftheria Silva, Luiz Vale High Energy Physics - Phenomenology High Energy Physics - Experiment We revisit the Standard Model description of the recently measured rare decays $D^0\toπ^+π^-\ell^+\ell^-$. Because of the effectiveness of the Glashow-Iliopoulos-Maiani mechanism in charm flavour-changing neutral currents, those decays are driven by non-local insertions of four-quark operators. Following previous work, we consider the mediation of resonances both for the dipion and dilepton pairs. For the first time, we incorporate the effect of the cascade-type topology $D^0\to π^- a_1^+(1260)(\toπ^+ρ^0(\to\ell^+\ell^-))$, which manifests distinctly in the invariant-mass and angular distributions. We find that this partial amplitude comprises one of the largest contributions to the decay rate and obtain an unprecedented agreement of the Standard Model prediction with the available LHCb data. Finally, we compare to the available CLEO-c, LHCb, and BESIII amplitude analyses for the analogous four-body hadronic decays and find that similar values of the hadronic parameters of our model successfully describe the two classes of decays. |
| title | Impact of the $a_1(1260) π$ cascade contribution on $D^0 \to π^+ π^- \ell^+ \ell^-$ decays |
| topic | High Energy Physics - Phenomenology High Energy Physics - Experiment |
| url | https://arxiv.org/abs/2511.02775 |