First measurement of the <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si1.gif" overflow="scroll"><mml:msup><mml:mi>π</mml:mi><mml:mo>+</mml:mo></mml:msup><mml:msup><mml:mi>π</mml:mi><mml:mo>−</mml:mo></mml:msup></mml:math> atom lifetime

Adeva, B.; Afanasyev, L.; Benayoun, M.; Benelli, A.; Berka, Z.; Brekhovskikh, V.; Caragheorgheopol, G.; Čechák, T.; Chiba, M.; Constantinescu, S.; Detraz, C.; Dreossi, Diego; Drijard, D.; Dudarev, A.; Evangelou, I.; Ferro‐Luzzi, M.; Gallas, M. V.; Gerndt, J.; Giacomich, R.; Gianotti, P.; Goldin, D.; Gómez, F.; Gorin, A.; Gorchakov, O.E.; Guaraldo, C.; Hansroul, M.; Hosek, R.; Iliescu, M.; Karpukhin, V.V.; Kluson, J.; Kobayashi, M.; Kokkas, P.; Komarov, V.I.; Kruglov, V.V.; Kruglova, L.; Kulikov, A.; Kuptsov, A.V.; Kurochkin, I.; Kuroda, K.; Lamberto, A.; Lanaro, A.; Lapshin, V.G.; Lednický, R.; Leruste, Ph.; Sandri, P. Levi; Agúera, A. López; Lucherini, V.; Mäki, T.; Manthos, N.; Manuilov, I.; Montanet, L.; Narjoux, J. L.; Nemenov, L.L.; Nikitin, M.; Pardo, T. Nunez; Okada, K.; Olchevskii, V.; Pazos, A.; Pentia, M.; Penzo, A.; Perreau, J.M.; Petrascu, C.; Pló, M.; Ponta, T.; Pop, D.; Rappazzo, G. F.; Fernandez, A. Rodriguez; Romero, A.; Ryazantsev, A.; Rykalin, V.I.; Santamarina, C.; Saborido, J.; Schacher, J.; Schuetz, C.; Sidorov, A.; Smolík, J.; Takéutchi, F.; Tarasov, A.V.; Tauscher, L.; Tobar, M.J.; Trusov, S.; Utkin, Victor A.; Doce, O. Vázquez; Vázquez, P.; Vlachos, S.; Yazkov, V.; Yoshimura, Y.; Zhabitsky, M.; Zrelov, P.

doi:10.1016/j.physletb.2005.05.045

Cited by 96 publications

(56 citation statements)

References 34 publications

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“…(28) are in very good agreement with the experimental results from pionic atoms [37,38] [26]. This is a considerable shift from the previous value of ð57:27 AE 0:82 exp AE 3 rad AE 1 ChPT appr Þ , in much better agreement with ours and other previous dispersive analyses.…”

Section: Comparison With Other Worksupporting

confidence: 91%

Pion-pion scattering amplitude. IV. Improved analysis with once subtracted Roy-like equations up to 1100 MeV

et al. 2011

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We improve our description of scattering data by imposing additional requirements on our previous fits, in the form of once-subtracted Roy-like equations, while extending our analysis up to 1100 MeV. We provide simple and ready to use parametrizations of the amplitude. In addition, we present a detailed description and derivation of these once-subtracted dispersion relations that, in the 450 to 1100 MeV region, provide an additional constraint which is much stronger than our previous requirements of forward dispersion relations and standard Roy equations. The ensuing constrained amplitudes describe the existing data with rather small uncertainties in the whole region from threshold up to 1100 MeV, while satisfying very stringent dispersive constraints. For the S0 wave, this requires an improved matching of the low and high energy parametrizations. Also for this wave we have considered the latest low energy K '4 decay results, including their isospin violation correction, and we have removed some controversial data points. These changes on the data translate into better determinations of threshold and subthreshold parameters which remove almost all disagreement with previous chiral perturbation theory and Roy equation calculations below 800 MeV. Finally, our results favor the dip structure of the S0 inelasticity around the controversial 1000 MeV region.

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Section: Comparison With Other Worksupporting

confidence: 91%

Pion-pion scattering amplitude. IV. Improved analysis with once subtracted Roy-like equations up to 1100 MeV

et al. 2011

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“…The value of a 0 0 is also compatible with experimental determinations [13] of this quantity, using a method devised by Cabibbo from K ! 0 0 decays, or from pionium decay [14] (although our results are more precise and do not depend on knowledge of a 2 0 ). Another question is whether one can improve our determinations.…”

mentioning

confidence: 65%

Experimental status of theππisoscalarSwave at low energy:f0(600)p

2007

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The experimental results obtained in the last few years on kaon decays (K ! 2 and, above all, Ke4 decays) allow a reliable, model-independent determination of low energy scattering in the S0 wave. Using them and, eventually, other sets of data, it is possible to give a precise parametrization of the S0 wave as well as to find the scattering length and effective range parameter. One can also perform an extrapolation to the pole of the ''sigma resonance'' [f

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“…In the meantime, the chiral perturbation series of the scattering amplitude has been worked out to NNLO [17] and, matching the chiral and dispersive representations, a very sharp prediction for the scattering lengths was obtained: a 0 0 = 0.220(5), a 2 0 = −0.0444(10) [13]. While the K e4 data of E865 [18], the DIRAC experiment [19] and the NA48 data on the cusp in K → 3π [20] all confirmed the theoretical expectations, the most precise source of information, the beautiful K e4 data of NA48 [21], gave rise to a puzzle. This experiment exploits the fact that -if the electromagnetic interaction and the difference between m u and m d are neglected -the relative phase of the form factors describing the decay K → eνππ coincides with the difference δ 0 0 − δ 1 1 of scattering phase shifts (Watson theorem).…”

Section: Precision Experiments At Low Energymentioning

confidence: 93%

On the low energy end of the QCD spectrum

Leutwyler

2009

Nuclear Physics B - Proceedings Supplements

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The experimental results on the Ke4 and K3π decays, those on pionic atoms and recent work on the lattice confirm the predictions obtained on the basis of χPT. As a result, the energy gap of QCD is now understood very well and there is no doubt that the expansion in powers of the two lightest quark masses does represent a very useful tool for the analysis of the low energy structure. Concerning the expansion in powers of ms, however, the current situation leaves much to be desired. While some of the lattice results indicate, for instance, that the violations of the OkuboIizuka-Zweig rule in the quark condensate and in the decay constants are rather modest, others point in the opposite direction. In view of the remarkable progress being made with the numerical simulation of light quarks, I am confident that the dust will settle soon, so that the effective coupling constants that govern the dependence of the various quantities of physical interest on ms can reliably be determined, to next-to-next-toleading order of the chiral expansion.The range of validity of χPT can be extended by means of dispersive methods. The properties of the physical states occurring in the spectrum of QCD below KK threshold can reliably be investigated on this basis. In particular, as shown only rather recently, general principles of quantum field theory lead to an exact formula that expresses the mass and width of resonances in terms of observable quantities. The formula removes the ambiguities inherent in the analytic continuation from the real axis into the complex plane, which plagued previous determinations of the pole positions of broad resonances. The application to the ππ partial wave amplitude with I = ℓ = 0 shows that there is a resonance in this channel, at Mσ − i 2 Γσ ≃ 441 − i 272 MeV: the lowest resonance of QCD carries the quantum numbers of the vacuum.Talks given at QCD08,

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First measurement of the π+π− atom lifetime

Cited by 96 publications

References 34 publications

Pion-pion scattering amplitude. IV. Improved analysis with once subtracted Roy-like equations up to 1100 MeV

Pion-pion scattering amplitude. IV. Improved analysis with once subtracted Roy-like equations up to 1100 MeV

Experimental status of theππisoscalarSwave at low energy:f0(600)p

On the low energy end of the QCD spectrum

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