Determination of ππ scattering lengths from measurement of <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.; Chliapnikov, P.; Ciocarlan, C.; Constantinescu, S.; Costantini, S.; Curceanu, C.; Doskarova, P.; Dreossi, Diego; Drijard, D.; Dudarev, A.; Ferro‐Luzzi, M.; Pazos, J.L. Fungueiriño; Torreira, Mercedes Gallas; Gerndt, J.; Gianotti, P.; Goldin, D.; Gómez, F.; Gorin, A.; Gorchakov, O.E.; Guaraldo, C.; Gugiu, M.; Hansroul, M.; Hons, Z.; 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.; Kuroda, K.; Lamberto, A.; Lanaro, A.; Lapshin, V.G.; Lednický, R.; Leruste, Ph.; Sandri, P. Levi; Agúera, A. López; Lucherini, V.; Mäki, T.; Manuilov, I.; Marin, J. C.; Narjoux, J. L.; Nemenov, L.L.; Nikitin, M.; Pardo, T. Nunez; Okada, K.; Olchevskii, V.; Pazos, A.; Pentia, M.; Penzo, A.; Perreau, J.M.; Pló, M.; Ponta, T.; Rappazzo, G. F.; Riazantsev, A.; Rodriguez, J. Molina; Fernandez, A. Rodriguez; Vidal, A. Romero; Ronjin, V. M.; Rykalin, V.I.; Saborido, J.; Santamarina, C.; Schacher, J.; Schuetz, C.; Sidorov, A.; Smolík, J.; Takéutchi, F.; Tarasov, A.V.; Tauscher, L.; Tobar, M.J.; Trojek, T.; Trusov, S.; Utkin, Victor A.; Doce, O. Vázquez; Vlachos, S.; Voskresenskaya, O. O.; Vrba, T.; Willmott, C.; Yazkov, V.; Yoshimura, Y.; Zhabitsky, M.; Zrelov, P.

doi:10.1016/j.physletb.2011.08.074

Cited by 41 publications

(23 citation statements)

References 22 publications

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“…In the meantime, this prediction has been tested in a series of beautiful low energy precision experiments 4 concerning the decays K → ℓνππ [83,84], K → πππ [85] and pionic atoms [86]. For the combination a (8) th , thus confirming the predictions to a remarkable degree of accuracy.…”

Section: Partial Wavesmentioning

confidence: 67%

Regge analysis of the ππ scattering amplitude

2012

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Abstract. The theoretical predictions for the subtraction constants lead to a very accurate dispersive representation of the ππ scattering amplitude below 0.8 GeV. The extension of this representation up to the maximum energy of validity of the Roy equations (1.15 GeV) requires a more precise input at high energies. In this paper we determine the trajectories and residues of the leading Regge contributions to the ππ amplitude (Pomeron, f and ρ), using factorization, phenomenological parametrizations of the πN and N N total cross sections at high energy and a set of sum rules which connect the high and low energy properties of ππ scattering. We find that nonleading Regge terms are necessary in order to achieve a smooth transition from the partial waves to the Regge representation at or below 2 GeV. We obtain thus a Regge representation consistent both with the experimental information at high energies and the Roy equations for the partial waves with ℓ ≤ 4. The uncertainties in our result for the Regge parameters are sizable but in the solutions of the Roy equations, these only manifest themselves above KK threshold. MotivationLow energy pion physics has become a precision laboratory: the chiral symmetry properties of the Standard Model can now be compared with low energy precision experiments, using Chiral Perturbation Theory (χPT), dispersion theory and numerical simulations of QCD on a lattice. In principle, as illustrated by the prediction for the magnetic moment of the muon, physics beyond the Standard Model can show up at low energies, provided the quantity of interest can not only be measured accurately, but can also be calculated to sufficient precision. In this context, the interaction among the pions and in particular, the elastic ππ scattering amplitude play a crucial role.The Roy equations [1] provide a suitable framework for the low energy analysis of the ππ scattering amplitude, as they fully incorporate the basic properties that follow from analyticity, unitarity and crossing symmetry. They express the real parts of the partial waves as integrals over the imaginary parts that extend over all energies. The high energy behaviour of the imaginary parts thus enters the analysis, even if the Roy equations are evaluated only at low energy. More specifically, the contributions from the high energy region are contained in the so-called driving terms. Near the ππ threshold, these terms are very small. Accordingly, the results for the threshold parameters are not sensitive to the high energy contributions. The driving terms, however, grow with the energy. In [2,4], where the threshold parameters and the coupling constants of the effective chiral SU(2)×SU(2) Lagrangian relevant for ππ scattering are determined to high accuracy, the Roy equations are solved only below 0.8 GeV. On general grounds [1] these equations are valid in the region 1 s ≤ 68 M 2 π , i.e. for √ s ≤ 1.15 GeV, but in order to use them we need an accurate evaluation of the driving terms. This calls for a better understanding of the imaginary ...

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Section: Partial Wavesmentioning

confidence: 67%

Regge analysis of the ππ scattering amplitude

2012

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“…1). Earlier this method was successfully applied to measure the lifetime of exotic π + π − atoms [5]. First evidence for πK atoms through the observation of (173 ± 54) πK atomic pairs produced on 26 μm Pt target in 2007 has been published [15].…”

Section: Experimental Methodsmentioning

confidence: 99%

“…For processes involving u-and d-quarks theoretical predictions have been experimentally checked by π + π − atom lifetime measurement [5] and by analysis of Kdecays [6,7]. Detection and lifetime measurement of πK atom cast a look into processes which involve s-quark as well.…”

Section: Introductionmentioning

confidence: 99%

FirstπKatom lifetime measurement and recent results from the DIRAC experiment

Zhabitsky

2014

EPJ Web of Conferences

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Abstract. We report evidence for πK atoms production, using 24 GeV/c proton beam from CERN PS interacting with a thin Ni target. We have identified (178 ± 49) πK pairs, which were produced in a bound state -πK atom, which was subsequently brokenup (ionized) in the Ni target. Our analysis yields a first measurement of the πK atom lifetime 2.5. This lifetime is connected in a model-independent way to the S-wave isospin-odd πK scattering length |a

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“…Study of π + π − atoms in the DIRAC experiment was fulfilled in collisions of 20 and 24 GeV/c protons, delivered by the CERN PS, hitting a thin nickel foil target of 94 or 98 µm thickness for different run periods [10]. Figure 2 shows observation of π + π − "atomic pairs" over the background of free pairs.…”

Section: Study Of π + π − Atomsmentioning

confidence: 99%

Study of Hadronic Hydrogen-like Atoms in the DIRAC Experiment at PS CERN

Afanasyev¹

2017

Acta Phys. Pol. B

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Production of hadronic hydrogen-like atoms at high-energy collisions and method of their observation are considered. Main results of the DIRAC experiment on observation and lifetime measurement of atoms formed by pairs of charged pion-pion and pion-kaon are presented. Physics of hadronic hydrogen-like atomsThe DIRAC experiment aims to observe and study hydrogen-like atoms formed by pairs of π + π − (A 2π ) and π ± K ∓ (A πK ) mesons using the 24 GeV extracted beam of PS CERN. The lifetime of these atoms is dictated by the strong interaction between the components. Thus combining hadrons into a hydrogen-like atom opens a unique possibility to study a property of the strong interaction at the very low relative momenta which are of the order of the atom Bohr momentum. For π + π − atom it is 0.5 MeV, for πK -0.8 MeV. Hence, the region of QCD confinement becomes available for investigation.The ground-state lifetime of π + π − atom τ 2π is governed by the ππ S-wave scattering lengths a I , with isospin I = 0, 2 [1-3]: 1/τ 2π ∝ |a 0 − a 2 | 2 . For the πK atom, the lifetime τ πK depends on the πK S-wave scattering lengths with isospin 1/2 and 3/2 [4]: 1/τ πK ∝ |a 1/2 − a 3/2 | 2 . The values of these scattering lengths can be rigorously calculated in the Chiral Perturbation Theory (ChPT) [5,6]. Last results of Lattice QCD [7] confirm this calculation. Thus, the measurement of the hadronic hydrogen-like atom lifetimes provides an experimental test of the low-energy QCD predictions.

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Determination of ππ scattering lengths from measurement of π+π− atom lifetime

Cited by 41 publications

References 22 publications

Regge analysis of the ππ scattering amplitude

Regge analysis of the ππ scattering amplitude

FirstπKatom lifetime measurement and recent results from the DIRAC experiment

Study of Hadronic Hydrogen-like Atoms in the DIRAC Experiment at PS CERN

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