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1. Search for $D^0$ meson decays to ${\pi }^{+}{\pi }^{-}{e}^{+}{e}^{-}$ and $K^{+}{K}^{-}{e}^{+}{e}^{-}$ final states

   https://doi.org/10.1103/PhysRevD.111.L091101  

   Aaij, R; Abdelmotteleb, A_S W; Abellan_Beteta, C; Abudinén, F; Ackernley, T; Adefisoye, A A; Adeva, B; Adinolfi, M; Adlarson, P; Agapopoulou, C; et al (May 2025, Physical Review D)

   A search for $D^0$meson decays to the ${\pi }^{+}{\pi }^{-}{e}^{+}{e}^{-}$and $K^{+}{K}^{-}{e}^{+}{e}^{-}$final states is reported using a sample of proton-proton collisions collected by the LHCb experiment at a center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of $6{\mathrm{fb}}^{-1}$. The decay $D^0\to {\pi }^{+}{\pi }^{-}{e}^{+}{e}^{-}$is observed for the first time when requiring that the two electrons are consistent with coming from the decay of a $\varphi$or ${\rho }^0/\omega$meson. The corresponding branching fractions are measured relative to the $D^0\to K^{-}{\pi }^{-}[e^{+}{e}^{-}{]}_{{\rho }^0/\omega }$decay, where the two electrons are consistent with coming from the decay of a ${\rho }^0$or $\omega$meson. No evidence is found for the $D^0\to K^{+}{K}^{-}{e}^{+}{e}^{-}$decay and world-best limits are set on its branching fraction. The results are compared to, and found to be consistent with, the branching fractions of the $D^0\to {\pi }^{+}{\pi }^{-}{\mu }^{+}{\mu }^{-}$and $D^0\to K^{+}{K}^{-}{\mu }^{+}{\mu }^{-}$decays recently measured by LHCb and confirm lepton universality at the current precision. © 2025 CERN, for the LHCb Collaboration2025CERN 

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2. Measurement of $CP$ Violation Observables in $D^{+}\to K^{-}{K}^{+}{\pi }^{+}$ Decays

   https://doi.org/10.1103/PhysRevLett.133.251801  

   Aaij, R; Abdelmotteleb, A_S W; Abellan_Beteta, C; Abudinén, F; Ackernley, T; Adefisoye, A A; Adeva, B; Adinolfi, M; Adlarson, P; Agapopoulou, C; et al (December 2024, Physical Review Letters)

   A search for violation of the charge-parity ( $CP$) symmetry in the $D^{+}\to K^{-}{K}^{+}{\pi }^{+}$decay is presented, with proton-proton collision data corresponding to an integrated luminosity of $5.4{\mathrm{fb}}^{-1}$, collected at a center-of-mass energy of 13 TeV with the LHCb detector. A novel model-independent technique is used to compare the $D^{+}$and $D^{-}$phase-space distributions, with instrumental asymmetries subtracted using the $D_s^{+}\to K^{-}{K}^{+}{\pi }^{+}$decay as a control channel. The $p$value for the hypothesis of $CP$conservation is 8.1%. The $CP$asymmetry observables $A_{CP|S}^{\varphi {\pi }^{+}}=(0.95\pm 0.43_{\mathrm{stat}}\pm 0.26_{\mathrm{syst}})\times {10}^{-3}$and $A_{CP|S}^{{\overline{K}}^{*0}{K}^{+}}=(-0.26\pm 0.56_{\mathrm{stat}}\pm 0.18_{\mathrm{syst}})\times {10}^{-3}$are also measured. These results show no evidence of $CP$violation and represent the most sensitive search performed through the phase space of a multibody decay. © 2024 CERN, for the LHCb Collaboration2024CERN 

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3. Angular analysis of the low $K^{+}{K}^{-}$ invariant mass enhancement in $B^{+}\to K^{+}{K}^{-}{\pi }^{+}$ decays

   https://doi.org/10.1103/PhysRevD.107.032013  

   Hsu, C.-L.; Sevior, M. E.; Adachi, I.; Aihara, H.; Al Said, S.; Asner, D. M.; Atmacan, H.; Aulchenko, V.; Aushev, T.; Ayad, R.; et al (February 2023, Physical Review D)
4. Angular Analysis of $D^0\to {\pi }^{+}{\pi }^{-}{\mu }^{+}{\mu }^{-}$ and $D^0\to K^{+}{K}^{-}{\mu }^{+}{\mu }^{-}$ Decays and Search for $CP$ Violation

   https://doi.org/10.1103/PhysRevLett.128.221801  

   Aaij, R.; Abdelmotteleb, A. S. W.; Abellán Beteta, C.; Abudinén, F.; Ackernley, T.; Adeva, B.; Adinolfi, M.; Afsharnia, H.; Agapopoulou, C.; Aidala, C. A.; et al (June 2022, Physical Review Letters)
5. Revisiting $C$ and $CP$ violation in $\eta \to {\pi }^{+}{\pi }^{-}{\pi }^0$ decay

   https://doi.org/10.1103/PhysRevD.110.055039  

   Shi, Jun; Liang, Jian; Gardner, Susan (September 2024, Physical Review D)

   The decay $\eta \to {\pi }^{+}{\pi }^{-}{\pi }^0$is an ideal process in which to study flavor-conserving $C$and $CP$violation beyond the Standard Model. We deduce the $C$- and $CP$-odd quark operators that contribute to $\eta \to {\pi }^{+}{\pi }^{-}{\pi }^0$originating from the mass-dimension-six Standard Model effective field theory. The corresponding hadron-level operators that generate a nonvanishing $I=0$amplitude at order $p^6$in the chiral effective theory are presented for the first time, to the best of our knowledge, in addition to the leading-order operators ascribed to the $I=2$final state. By fitting the KLOE-2 and the most recent BESIII experimental data, we determine the coefficients of the lowest-order $I=0$and $I=2$amplitudes and estimate the potential new physics energy scale. We also perform an impact study of the future $\eta \to {\pi }^{+}{\pi }^{-}{\pi }^0$experiments. Published by the American Physical Society2024 

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