Conferencia
Abstract:
We make an improvement of the dispersion relation calculation of the quadratic scalar radius of the pion, 〈r2〉s pπ, and the reaction γγ → π0 π0. We solve a previous discrepancy between the the solution of the Muskhelishvili-Omnès equations for the non-strange null isospin (I) pion scalar form factor and the Indurain's calculation using an Omnès representation of this form factor. We show that Ynduráin's method is indeed compatible with the determinations from the Muskhelishvili-Omnès equations once a possible zero in the scalar form factor is considered. Once this is accounted for, the resulting value is 〈r2〉 s pπ = 0.63 ±0.05 fm2. Regarding the reaction γγ → π0 π0 we emphasize how the f0(980) signal emerges in γγ → ππ within the dispersive approach and how this fixes to a large extent the phase of the isoscalar S-wave γγ → ππ amplitude above the KK̄ threshold. This allows us to make sharper predictions for the cross section at lower energies and our results could then be used to distinguish between different ππ isoscalar S-wave parameterizations with the advent of new precise data on γγ → π0π0. We also pay special attention to the role played by the σ resonance in γγ → ππ and calculate its coupling and width to γγ, for which we obtain Λ(σ → γγ) = ( 1.68 ± 0.15) KeV. © Copyright owned by the author(s) under the terms of the Creative Commons Attribution-NonCommercial-ShareAlike Licence.
Registro:
| Documento: | Conferencia |
| Título: | Scalar radius of the pion and γγ → ππ |
| Autor: | Roca, L.; Oller, J.A.; Schat, C. |
| Ciudad: | Valencia |
| Filiación: | Departamento de Física, Universidad de Murcia, E-30071, Spain Departamento de Física, FCEyN, Ciudad Universitaria, Pab. 1, (1428) Buenos Aires, Argentina |
| Palabras clave: | Dispersion relations; Form factors; Isospin; Lower energies; Approximation theory; Dispersions; Shear waves; Stress intensity factors; Hadrons |
| Año: | 2009 |
| Título revista: | International Workshop on Effective Field Theories: From the Pion to the Upsilon, EFT 2009 |
| Título revista abreviado: | Proc. Sci. |
| ISSN: | 18248039 |
| Registro: | https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_18248039_v_n_p_Roca |
Referencias:
- Oller, J.A., Roca, L., (2007) Phys. Lett., B651, p. 139
- Oller, J.A., Roca, L., Schat, C., (2008) Phys. Lett. B, 659, p. 201. , [arXiv:0708.1659 [hep-ph]]
- Oller, J.A., Roca, L., (2008) Eur. Phys. J. A, 37, p. 15. , [arXiv:0804.0309 [hep-ph]]
- Ynduráin, F.J., (2004) Phys. Lett., B578, p. 99. , (E)-ibid B586, 439 (2004)
- Ynduráin, F.J., (2005) Phys. Lett., B612, p. 245
- F. J. Ynduráin, arXiv:hep-ph/0510317; Pennington, M.R., (2006) Phys. Rev. Lett., 97, p. 011601
- Colangelo, G., Gasser, J., Leutwyler, H., (2001) Nucl. Phys., B603, p. 125
- Gasser, J., Leutwyler, H., (1983) Phys. Lett., B125, p. 325
- Colangelo, G., Dür, S., (2004) Eur. Phys. J., C33, p. 543
- Donoghue, J.F., Gasser, J., Leutwyler, H., (1990) Nucl. Phys., B343, p. 341
- Gasser, J., Meißner, U.-G., (1991) Nucl. Phys., B357, p. 90
- Meißner, U.G., Oller, J.A., (2001) Nucl. Phys., A679, p. 671
- Bijnens, J., Colangelo, G., Talavera, P., (1998) JHEP, 9805, p. 014
- Morgan, D., Pennington, M.R., (1991) Phys. Lett., B272, p. 134
- (1988) Z. Phys., C37, p. 431. , [Erratum-ibid. C 39, 590 (1988)]
- Mori, T., (2007) Phys. Rev., D75, p. 051101. , [Belle Collaboration]
- Ananthanarayan, B., Caprini, I., Colangelo, G., Gasser, J., Leutwyler, H., (2004) Phys. Lett., B602, p. 218
- Peláez, J.R., Ynduráin, F.J., (2003) Phys. Rev., D68, p. 074005. , ibid D71, 074016 (2005)
- Albaladejo, M., Oller, J.A., (2008) Phys. Rev. Lett., 101, p. 252002. , [arXiv:0801.4929 [hep-ph]]
- Marsiske, H., (1990) Phys. Rev., D41, p. 3324. , [Crystal Ball Collab.]
- Caprini, I., Colangelo, G., Leutwyler, H., (2006) Phys. Rev. Lett., 96, p. 132001
Citas:
---------- APA ----------
Roca, L., Oller, J.A. & Schat, C. (2009) . Scalar radius of the pion and γγ → ππ. International Workshop on Effective Field Theories: From the Pion to the Upsilon, EFT 2009.Recuperado de https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_18248039_v_n_p_Roca [ ]
---------- CHICAGO ----------
Roca, L., Oller, J.A., Schat, C. "Scalar radius of the pion and γγ → ππ" . International Workshop on Effective Field Theories: From the Pion to the Upsilon, EFT 2009 (2009).Recuperado de https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_18248039_v_n_p_Roca [ ]
---------- MLA ----------
Roca, L., Oller, J.A., Schat, C. "Scalar radius of the pion and γγ → ππ" . International Workshop on Effective Field Theories: From the Pion to the Upsilon, EFT 2009, 2009.Recuperado de https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_18248039_v_n_p_Roca [ ]
---------- VANCOUVER ----------
Roca, L., Oller, J.A., Schat, C. Scalar radius of the pion and γγ → ππ. Proc. Sci. 2009.Available from: https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_18248039_v_n_p_Roca [ ]
