Possible manifestation of the 2p pionium in particle physics processes

Abstract

We suggest a few particle physics processes in which excited 2p pionium ${\mathrm{A}}_{2\pi }^{\prime }$ may be observed. They include the $e^{+}{e}^{-}\to {\pi }^{+}{\pi }^{-}$ annihilation, the $V^0\to {\pi }^0{\ell }^{+}{\ell }^{-}$ and $K^{\pm }\to {\pi }^{\pm }{\ell }^{+}{\ell }^{-}$ ($\ell =e,\mu$) decays, and the photoproduction of two neutral pions from nucleons. We analyze available experimental data and find that they, in some cases, indicate the presence of 2p pionium, but do not provide definite proof.

arXiv comment11 pages, 11 figures, 5 tables

References in corpus (41)

• Precise Measurement of the e+ e- --> pi+ pi- (gamma) Cross Section with the Initial-State Radiation Method at BABAR
• Measuring sigma(e^+e^- \to hadrons) using tagged photon
• Search for $K_L\to {\pi }^0\nu \overline{\nu }$ and $K_L\to {\pi }^0{X}^0$ Decays at the J-PARC KOTO Experiment
• Spectroscopy at B-factories Using Hard Photon Emission
• Study of the electromagnetic transition form-factors in η-> μ^+μ^-γand ω-> μ^+μ^-π^0 decays with NA60
• Dispersive analysis of omega --> 3pi and phi --> 3pi decays
• omega --> pi0 gamma* and phi --> pi0 gamma* Transition form factors in dispersion theory
• The Decays $K\to \pi {\ell }^{+}{\ell }^{-}$ beyond Leading Order in the Chiral Expansion
• Determination of the a0-a2 pion scattering length from K->pi+ pi0 pi0 decay
• First measurement of the ${\pi }^{+}{\pi }^{-}$ atom lifetime
• Dilepton Spectra from Decays of Light Unflavored Mesons
• Observation of a cusp-like structure in the pizero-pizero invariant mass distribution from K+- ==> pi+- pizero pizero decay and determination of the pi-pi scattering lengths
• Hadronic atoms in QCD + QED
• Decays of the pi+ pi- atom
• Hadronic Cross Sections in Electron-Positron Annihilation with Tagged Photon
• Electromagnetic transition form factors of light vector mesons
• New measurement of the K+- --> pi+-mu+mu- decay
• Precise measurement of the K+- --> pi+-e+e- decay
• A new measurement of the properties of the rare decay K -> pi+ e+ e-
• First search for $K^{+}\to {\pi }^{+}\nu \bar{\nu }$ using the decay-in-flight technique
• Precision study of the $\eta \to {\mu }^{+}{\mu }^{-}\gamma$ and $\omega \to {\mu }^{+}{\mu }^{-}{\pi }^0$ electromagnetic transition form-factors and of the $\rho \to {\mu }^{+}{\mu }^{-}$ line shape in NA60
• Measurement of the omega -> pi^0 e^+e^- and eta -> e^+e^-g Dalitz decays with the A2 setup at MAMI
• Determination of $\pi \pi$ scattering lengths from measurement of ${\pi }^{+}{\pi }^{-}$ atom lifetime
• Relativistic effects in the pionium lifetime
• Electromagnetic transitions in an effective chiral Lagrangian with the eta-prime and light vector mesons
• DIRAC: A High Resolution Spectrometer for Pionium Detection
• Measurement of the $\varphi \to {\pi }^0{e}^{+}{e}^{-}$ transition form factor with the KLOE detector
• Two-Hadron Saturation for the Pseudoscalar-Vector-Vector Correlator and Phenomenological Applications
• Observation of the Decay K- -> pi- mu+ mu- and Measurements of the Branching Ratios for K+/- -> pi+/- mu+ mu-
• Some implications of meson dominance in weak interactions
• A New Measurement of the Rare Decay $K^{+}\to {\pi }^{+}{\mu }^{+}{\mu }^{-}$
• (Pi+Pi-) Atom in Chiral Perturbation Theory
• Observation of the Decay K+ --> pi+ mu+ mu-
• Constraints on the $\omega \pi$ form factor from analyticity and unitarity
• Hadronic Atoms
• Are the production and decay of a resonance always independent?
• Running mass of the rho0 meson's implication for the dilepton mass spectrum and the mu+mu-/e+e- branching ratio in the K+ --> pi+l+l- decays
• Helicity-dependent cross sections for the photoproduction of ${\pi }^0$ pairs from nucleons
• Tri-meson-mixing of $\pi$-$\eta$-${\eta }^{\prime }$ and $\rho$-$\omega$-$\varphi$ in the light-cone quark model
• First measurement of a long-lived ${\pi }^{+}{\pi }^{-}$ atom lifetime
• Manifestation of kaonium in the $e^{+}{e}^{-}\to K^{+}{K}^{-}$ process

Cited by in corpus (1)

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