$S$-wave contribution to rare $D^0 \to \pi^+ \pi^- \ell^+ \ell^-$ decays in the standard model and sensitivity to new physics

Fajfer, Svjetlana (author), Solomonidi, Eleftheria (author), Vale Silva, Luiz (author)

Physics of the up-type flavor offers unique possibilities of testing the standard model (SM) compared to the down-type flavor sector. Here, we discuss SM and new physics (NP) contributions to the rare charm-meson decay $D^0 \to \pi^+ \pi^- \ell^+ \ell^-$. In particular, we discuss the effect of including the lightest scalar isoscalar resonance in the SM picture, namely, the $f_0$(500), which manifests in a big portion of the allowed phase space. Other than showing in the total branching ratio at an observable level of about 20%, the $f_0$(500) resonance manifests as interference terms with the vector resonances, such as at high invariant mass of the leptonic pair in distinct angular observables. Recent data from LHCb optimize the sensitivity to P-wave contributions that we analyze in view of the inclusion of vector resonances. We propose the measurement of alternative observables that are sensitive to the S-wave and are straightforward to implement experimentally. This leads to a new set of null observables that vanish in the SM due to its gauge and flavor structures. Finally, we study observables that depend on the SM interference with generic NP contributions from semileptonic four-fermion operators in the presence of the S-wave.

• Language: English
• Keywords: physics of elementary particles, particle decays
• Work type: Article
• Typology: 1.01 - Original Scientific Article
• Organization: FMF - Faculty of Mathematics and Physics
• Publication version: Version of Record
• Publication date: 26.02.2024
• Year: 2024
• Number of pages: Str. 036027-1-036027-24
• Numbering: Vol. 109, iss. 3
• PID: 20.500.12556/RUL-154952
• UDC: 539.1
• ISSN on article: 2470-0010
• DOI: 10.1103/PhysRevD.109.036027
• COBISS.SI-ID: 188456963
• Publication date in RUL: 11.03.2024

Record is a part of a journal

• Title: Physical review
• Shortened title: Phys. rev., D
• Publisher: American Physical Society
• ISSN: 2470-0010
• COBISS.SI-ID: 29757223

Licences

• License: CC BY 4.0, Creative Commons Attribution 4.0 International
• Link: http://creativecommons.org/licenses/by/4.0/
• Description: This is the standard Creative Commons license that gives others maximum freedom to do what they want with the work as long as they credit the author.

Secondary language

• Language: Slovenian
• Keywords: fizika osnovnih delcev, razpadi delcev