On the history of pion-pion scattering

Gasser, J.

doi:10.22323/1.069.0029

Cited by 9 publications

(14 citation statements)

References 58 publications

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“…The inclusion of this effect brought the NA48/2 measurement of the scattering lengths into perfect agreement with the prediction of the χ PT/Roy equation analysis [11]. For a review of these developments, see [12]. The mass effects on the phases at two-loop order have been recently studied in an elaborate dispersive framework [13], which confirms the previous results.…”

Section: Introductionsupporting

confidence: 77%

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Isospin breaking effects in $$K_{\ell 4}$$ K ℓ 4 decays

Stoffer

2014

Eur. Phys. J. C

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In the framework of chiral perturbation theory with photons and leptons, the one-loop isospin-breaking effects in K 4 decays due to both the photonic contribution and the quark and meson mass differences are computed. A comparison with the isospin-breaking corrections applied by recent high statistics K e4 experiments is performed. The calculation can be used to correct the existing form factor measurements by isospin-breaking effects that have not yet been taken into account in the experimental analysis. Based on the present work, possible forthcoming experiments on K e4 decays could correct the isospin breaking effects in a more consistent way.

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Section: Introductionsupporting

confidence: 77%

“…Still, the phase space is parametrised by the same five kinematic variables and the differential decay rate can be written as in (12). In the isospin broken case, the presence of the additional tensorial form factor changes the function J 5 .…”

Section: Matrix Element Form Factors and Decay Ratementioning

confidence: 99%

Isospin breaking effects in $$K_{\ell 4}$$ K ℓ 4 decays

Stoffer

2014

Eur. Phys. J. C

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“…Using the central value and adopting the central values of the scattering lengths summarized in Ref. [25], a 0 = 0.2196 and a 2 = −0.0444 in units of M −1 π + , the cusp effect in the NREFT is plotted in Fig. 4.…”

Section: Chiral Unitary Approachmentioning

confidence: 99%

Extracting ππ S-wave scattering lengths from cusp effect in heavy quarkonium dipion transitions

2013

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Charge-exchange rescattering π + π − → π 0 π 0 leads to a cusp effect in the π 0 π 0 invariant mass spectrum of processes with π 0 π 0 in the final state which can be used to measure ππ S-wave scattering lengths. Employing a non-relativistic effective field theory, we discuss the possibility of extracting the scattering lengths in heavy quarkonium π 0 π 0 transitions. The transition Υ(3S) → Υ(2S)π 0 π 0 is studied in details. We discuss the precision that can be reached in such an extraction for a certain number of events.

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“…At the same time, measurements of the pion-nucleon cross section have been restricted so far to rather low energies, up to about √ s = 35 GeV [3]. The pion-pion cross section cannot be measured directly, and has been extracted from data only at very low energies near threshold [4]. The theoretical description of elastic scattering has been based so far only on phenomenological models.…”

Section: Introductionmentioning

confidence: 99%

Pion-pion cross section from proton-proton collisions at the LHC

et al. 2015

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The zero-degree calorimeters (ZDC) installed in the ALICE, ATLAS and CMS experiments at the LHC, make possible simultaneous detection of forward-backward leading neutrons, pp → n X n. Such data with sufficiently high statistics could be a source of information about the pion-pion total cross section at high energies, provided that the absorption corrections, which are expected to be strong, are well understood. Otherwise, making a plausible assumption about the magnitude of the pion-pion cross section, one can consider such measurements as a way to study the absorption effects, which is the main focus of the present paper. These effects introduced at the amplitude level, are found to be different for the pion fluxes, which either conserve or flip the nucleon helicity. The pion fluxes from both colliding protons are essentially reduced by absorption, moreover, there is a common absorption suppression factor, which breaks down the factorized form of the cross section. We also evaluate the feed-down corrections related to the initial/final state inelastic processes possessing a rapidity gap, and found them to be small in the kinematic range under consideration. The contribution of other iso-vector Reggeons, spin-flip natural parity ρ and a2, and spin non-flip unnatural parity a1 are also evaluated and found to be rather small.

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On the history of pion-pion scattering

Abstract: Highlights in the history of pion-pion scattering are discussed, starting with Yukawa's hypothesis that pion exchange is responsible for nuclear forces, and ending with the NA48/2 analysis of K e4 and K → 3π decays. No claim for completeness is made.

Cited by 9 publications

References 58 publications

Isospin breaking effects in $$K_{\ell 4}$$ K ℓ 4 decays

Isospin breaking effects in $$K_{\ell 4}$$ K ℓ 4 decays

Extracting ππ S-wave scattering lengths from cusp effect in heavy quarkonium dipion transitions

Pion-pion cross section from proton-proton collisions at the LHC

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