WorldWideScience

Sample records for pionium

  1. Second-order corrections to the wave function at origin in muonic hydrogen and pionium

    CERN Document Server

    Ivanov, Vladimir G; Karshenboim, Savely G

    2009-01-01

    Non-relativisitic second-order corrections to the wave function at origin in muonic and exotic atoms are considered. The corrections are due to the electronic vacuum polarization. Such corrections are of interest due to various effective approaches, which take into account QED and hadronic effects. The wave function at origin plays a key role in the calculation of the pionium lifetime, various finite nuclear size effects and the hyperfine splitting. The results are obtained for the $1s$ and $2s$ states in pionic and muonic hydrogen and deuterium and in pionium, a bound system of $\\pi^+$ and $\\pi^-$. Applications to the hyperfine structure and the Lamb shift in muonic hydrogen are also considered.

  2. Coherent production of the long-lived pionium nP states in relativistic nucleus-nucleus collisions

    CERN Document Server

    Gevokyan, S

    2015-01-01

    The coherent production of the $nP$ states of the $\\pi^+\\pi^-$ atoms ($A_{2\\pi}$) in relativistic nucleus-nucleus collisions is considered as a possible source of the $A_{2\\pi}(nP)$ beam for the pionium Lamb-shift measurement. A general expression for estimation of the $A_{2\\pi}(nP)$ yields is derived in the framework of the equivalent photon approximation.

  3. A Pionic Hadron Explains the Muon Magnetic Moment Anomaly

    CERN Document Server

    Schiel, Rainer W

    2007-01-01

    Quantum electrodynamics is the most successful physical theory in history. Yet for several years a significant experimental discrepancy has existed. Calculations disagree with measurements of the muon's magnetic moment, which is a fundamental test of the theory. A new contribution hidden in plain view explains the current discrepancy. Mixing of the rho meson and pionium, the bound state atom of pion and anti-pion, must be treated as a new elementary particle, the second least-massive hadron. Surprisingly, the existence of the particle state is undeniable. Yet superposition of pionium and rho must contradict basic assumptions of pion physics, and may be the first case in which an orbitally asymmetric hadron has mass below the symmetric case, due to quark microstructure that cannot be described by pions at all.

  4. Dimesoatoms production in high energy collisions

    CERN Document Server

    Afanasyev, L; Voskresenskaya, O

    2016-01-01

    The production of two meson electromagnetic bound states and free meson pairs $\\pi^+\\pi^-$, $K^+K^-$, $\\pi^+ K^{\\mp}$ in relativistic collisions has been considered. It was shown that making use of the exact Coulomb wave function for dimesoatom (DMA) allows one to calculate the yield of any nS state with desired accuracy. The relative probabilities of production of DMA and meson pairs in the free state are estimated. The amplitude of DMA transition from 1S to 2P state, which is essential for the pionium Lamb shift measurements, has been obtained.

  5. Production of dimeson atoms in high-energy collisions

    Science.gov (United States)

    Afanasyev, L.; Gevorkyan, S.; Voskresenskaya, O.

    2017-04-01

    The production of two-meson electromagnetic bound states and free meson pairs π^+π^- , K^+K^- , π^+K^{∓} in relativistic collisions has been considered. It is shown that using of exact Coulomb wave functions for dimeson atom (DMA) allows one to calculate the yield of discrete states with the desired accuracy. The relative probabilities of production of DMA and meson pairs in the free state are estimated. The amplitude of DMA transition from 1 S to 2 P state, which is essential for the pionium Lamb shift measurements, has been obtained.

  6. Production of dimeson atoms in high-energy collisions

    Energy Technology Data Exchange (ETDEWEB)

    Afanasyev, L.; Gevorkyan, S.; Voskresenskaya, O. [Joint Institute for Nuclear Research, Dubna (Russian Federation)

    2017-04-15

    The production of two-meson electromagnetic bound states and free meson pairs π{sup +}π{sup -}, K{sup +}K{sup -}, π{sup +}K{sup -+} in relativistic collisions has been considered. It is shown that using of exact Coulomb wave functions for dimeson atom (DMA) allows one to calculate the yield of discrete states with the desired accuracy. The relative probabilities of production of DMA and meson pairs in the free state are estimated. The amplitude of DMA transition from 1S to 2P state, which is essential for the pionium Lamb shift measurements, has been obtained. (orig.)

  7. Radiative corrections in K --> 3 pi decays

    CERN Document Server

    Bissegger, M; Gasser, J; Kubis, B; Rusetsky, A

    2008-01-01

    We investigate radiative corrections to K --> 3 pi decays. In particular, we extend the non-relativistic framework developed recently to include real and virtual photons and show that, in a well-defined power counting scheme, the results reproduce corrections obtained in the relativistic calculation. Real photons are included exactly, beyond the soft-photon approximation, and we compare the result with the latter. The singularities generated by pionium near threshold are investigated, and a region is identified where standard perturbation theory in the fine structure constant alpha may be applied. We expect that the formulae provided allow one to extract S-wave pi pi scattering lengths from the cusp effect in these decays with high precision.