ππ scattering

Leutwyler, H.

doi:10.1016/s0550-3213(01)00147-x

Cited by 1,008 publications

(2,065 citation statements)

References 99 publications

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“…[4], provided that the same set of LECs is used. With updated LECs at order p 4 [6,7], we find for the dipole polarizabilities the value (α 1 − β 1 ) π ± = (5.7 ± 1.0) × 10 −4 fm 3 .…”

Section: Introductionmentioning

confidence: 88%

Revisiting at low energies

2006

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We complete the recalculation of the available two-loop expressions for the reaction γγ → ππ in the framework of chiral perturbation theory. Here, we present the results for charged pions. The cross section and the values of the dipole polarizabilities agree very well with the earlier calculation, provided the same set of low-energy constants (LECs) is used. With updated values for the LECs at order p 4 , we find for the dipole polarizabilities (α 1 − β 1 ) π ± = (5.7 ± 1.0) × 10 −4 fm 3 , which is in conflict with the experimental result recently reported by the MAMI Collaboration.

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Section: Introductionmentioning

confidence: 88%

Revisiting at low energies

2006

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“…In order to transfer the beam momentum almost completely to the emerging particle it has to be emitted in the forward direction close at zero degrees. The momentum transferred from the beam to 3 He being emitted at zero degrees are shown in Fig. 31 and for different assumptions of the η binding energy.…”

Section: Transfer Reactionsmentioning

confidence: 99%

“…In a fit In Fig. 48 we compare the excitation functions for the present reaction with the one for d + p → η+ 3 He. The latter reaction shows a much more He.…”

Section: The Reaction D + D → η+ 4 Hementioning

confidence: 99%

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Search for quasi boundηmesons

Machner

2015

J. Phys. G: Nucl. Part. Phys.

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The search for a quasi bound η meson in atomic nuclei is reviewed. This tentative state is studied theoretically as well as experimentally. The theory starts from elastic η nucleon scattering which is derived from production data within some models. From this interaction the η nucleus interaction is derived. Model calculations predict binding energies and widths of the quasi bound state. Another method is to derive the η nucleus interaction from excitation functions of η production experiments. The s wave interaction is extracted from such data via final state interaction theorem. We give the derivation of s wave amplitudes in partial wave expansion and in helicity amplitudes and their relation to observables. Different experiments extracting the final state interaction are discussed as are production experiments. So far only three experiments give evidence for the existence of the quasi bound state: a pion double charge exchange experiment, an effective mass measurement, and a transfer reaction at recoil free kinematics with observation of the decay of the state.

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“…Regarding the SU(2) low energy constantsl i andr i (µ) we use the values obtained in Ref. [29,22]; for the SU(3) low energy constants L r i (µ) we refer to the O(p 4 ) fit of Ref. [30].…”

Section: Numerical Analysismentioning

confidence: 99%

Finite volume effects for meson masses and decay constants

2005

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We present a detailed numerical study of finite volume effects for masses and decay constants of the octet of pseudoscalar mesons. For this analysis we use chiral perturbation theory and asymptotic formulaeà la Lüscher and propose an extension of the latter beyond the leading exponential term. We argue that such a formula, which is exact at the one-loop level, gives the numerically dominant part at two loops and beyond. Finally, we discuss the possibility to determine low energy constants from the finite volume dependence of masses and decay constants.

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ππ scattering

Cited by 1,008 publications

References 99 publications

Revisiting at low energies

Revisiting at low energies

Search for quasi boundηmesons

Finite volume effects for meson masses and decay constants

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