Isovector kaon form factor in the dispersion theory and S-wave ? K-scattering lengths

1995 ◽  
Vol 350 (4) ◽  
pp. 343-347 ◽  
Author(s):  
M. I. Krivoruchenko
Keyword(s):  
Form Factor ◽  
Dispersion Theory ◽  
S Wave ◽  
Scattering Lengths

scholarly journals Elementary Particle Scattering Lengths and Resonances

1974 ◽  
Vol 27 (1) ◽  
pp. 13
Author(s):  
DC Peaslee
Keyword(s):  
Optical Potential ◽  
Scattering Length ◽  
Compound System ◽  
Zero Energy ◽  
S Wave ◽  
Nucleon System ◽  
Level Shifts ◽  
Wave States ◽  
Scattering Lengths

An investigation is made of the relation between scattering lengths and resonances in a two-nucleon system. For resonances Eo near zero energy the usual determination of an effective optical potential in mesonic atoms is limited, and it is shown here that the scattering length can only be represented usefully as a sum over resonances of the compound system if the condition IEolDI ~ (PDo)! Is satisfied, where D is the average spacing of s-wave states, p the density of target nucleons and Do the Compton volume of the reduced system. This condition is seen to be valid for mr:, nK and KK interactions and these systems are considered in some detail. It is shown that knowledge of the level shifts of each of these examples can help resolve present uncertainties in associated boson structure.

CUSPS IN THE KAON DECAYS

2009 ◽  
Vol 24 (02n03) ◽  
pp. 214-221
Author(s):  
AKAKI RUSETSKY
Keyword(s):  
Effective Field Theory ◽  
Neutral Pion ◽  
Effective Field ◽  
S Wave ◽  
Kaon Decays ◽  
Cusp Region ◽  
The Difference ◽  
Scattering Lengths ◽  
Theory Framework

We consider two ways of the experimental determination of the S-wave ππ scattering lengths: from K → 3π decays and from Ke4 decays. In both cases the unitary cusps, which emerge due to the difference in the charged and neutral pion masses, play a crucial role. We construct a systematic effective field theory framework which can be used to describe decay amplitudes in the cusp region.

scholarly journals Determination of the S-wave π π scattering lengths from a study of K ±→π ± π 0 π 0 decays

2009 ◽  
Vol 64 (4) ◽  
pp. 589-608 ◽  
Author(s):  
J. R. Batley ◽  
A. J. Culling ◽  
G. Kalmus ◽  
C. Lazzeroni ◽  
D. J. Munday ◽  
...  
Keyword(s):  
S Wave ◽  
Scattering Lengths

PION AND ρ MESON OBSERVABLES IN A NAMBU–JONA-LASINIO MODEL INCLUDING A TENSOR INTERACTION

2002 ◽  
Vol 17 (32) ◽  
pp. 4903-4925 ◽  
Author(s):  
M. JAMINON ◽  
M. C. RUIVO ◽  
C. A. DE SOUSA
Keyword(s):  
Form Factor ◽  
Electromagnetic Form Factor ◽  
Tensor Interaction ◽  
Text Structure ◽  
Strong Increase ◽  
Total Width ◽  
Scalar Form Factor ◽  
Dominance Model ◽  
Scalar Form ◽  
Scattering Lengths

We calculate the low energy π π scattering lengths [Formula: see text] and [Formula: see text], the coupling of the ρ to the pion gρ π π, the total width of the ρ, the low q2 behavior of the pion electromagnetic form factor, and the pion scalar form factor within a chiral SU(2) f NJL-type Lagrangian where the spin 1 ρ meson is generated from a four-quark tensor interaction. Such a simple model avoids the mathematical complication related to π - a1 mixing. Two types of regularization are discussed, mainly affecting the values of [Formula: see text] and [Formula: see text]. We find rather good agreement with data. The ρ meson described in this way does not account for the meson vector dominance model: it does not contribute to the [Formula: see text] scattering lengths, and the charge radius of the pion is mainly ascribed to the bare photon quark coupling. Even if the shape of the electromagnetic form factor is well reproduced, the strong increase near the ρ pole does not account for the ρ→ππ decay but only reflects the [Formula: see text] structure of the ρ.

scholarly journals RECENT NA48/2 RESULTS ON Ke4 AND K3π DECAYS AND DETERMINATION OF THE ππ SCATTERING LENGTHS

2009 ◽  
Vol 24 (02n03) ◽  
pp. 488-492
Author(s):  
◽  
ANDREA BIZZETI
Keyword(s):  
Mass Spectrum ◽  
Invariant Mass ◽  
High Precision ◽  
Form Factors ◽  
Invariant Mass Spectrum ◽  
S Wave ◽  
Large Samples ◽  
Scattering Lengths

Large samples of K± → 3π and K± → π+π-e±ν (Ke4) decays have been collected by the NA48/2 experiment at CERN SPS. At the π+π- threshold, the π0π0 invariant mass spectrum of the decay K± → π±π0π0 xhibits a Wigner cusp, from which the S-wave ππ scattering lengths are extracted with high precision. The same scattering lengths are also independently determined from the accurate measurement of the form factors in the Ke4 decay K± → π+π-e±ν.

PIONIC HYDROGEN

2005 ◽  
Vol 20 (02n03) ◽  
pp. 349-357 ◽  
Author(s):  
◽  
DETLEV GOTTA
Keyword(s):  
Coupling Constant ◽  
S Wave ◽  
Pionic Hydrogen ◽  
Pion Nucleon ◽  
Scattering Lengths ◽  
Set Up ◽  
Paul Scherrer ◽  
S States ◽  
Precision Test ◽  
Pertubation Theory

The measurement of the pion–nucleon scattering lengths constitutes a high–precision test of the methods of Chiral Pertubation Theory (χPT), which is the low–energy approach of QCD. The πN s–wave scattering lengths and the pion–nucleon coupling constant are related to the strong–interaction shift ∊1s and width Γ1s of the s–states in the pionic hydrogen atom. ∊1s and Γ1s are determined from the measured energies and line widths of X–ray transitions to the 1s ground state when compared to the calculated electromagnetic values. A new experiment, set up at the Paul–Scherrer–Institut (PSI), has completed a first series of measurements.

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