Measurement of the pion form factor in the time-like region for q2 values between 0.1 (GeV/c)2 and 0.18 (GeV/c)2

Amendolia, S. R.; Badełek, B.; Batignani, G.; Beck, G.A.; Bellamy, E.H.; Bertolucci, E.; Bettoni, D.; Bilokon, H.; Bizzeti, A.; Bologna, G.; Bosisio, L.; Bradaschia, C.; Budinich, Marco; Dell’Orso, M.; Piazzoli, B. D. D'Ettorre; Enorini, M.; Fabbri, F. L.; Fidecaro, F.; Foà, L.; Focardi, E.; Frank, S.; Giannetti, P.; Giazotto, A.; Giorgi, M. A.; Harvey, J.; Heath, G. P.; Landon, M. P. J.; Laurelli, P.; Liello, F.; Mannocchi, G.; March, P.V.; Marrocchesi, P. S.; Menasce, D.; Menzione, A.; Meroni, E.; Milotti, E.; Moroni, L.; Picchi, P.; Ragusa, F.; Ristori, L.; Rolandi, G.; Saltmarsh, C.; Saoucha, A.; Satta, L.; Scribano, A.; Stefanini, A.; Strong, J. A.; Тенчини, Р.; Tonelli, G.; Triggiani, G.; Zallo, A.

doi:10.1016/0370-2693(84)91938-5

Cited by 98 publications

(12 citation statements)

References 6 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Identifying F p (0) as the pion decay constant f p in the static limit, we find that it comes out to be 0.086 GeV, which is in reasonable agreement with the experimental value 0.093 GeV. In this calculation, we have used the value of RMS charge radius of the pion r p as 0.66 fm, which is its experimental value [54]. The value of F p (0) in this model is infinite in the limit of vanishing pion mass, which is unlike the observation of Donoghue and Johnson [37].…”

Section: Resultssupporting

confidence: 70%

( q q ¯ ) -pion mass and decay constant in a relativistic independent-quark model

2009

View full text Add to dashboard Cite

The mass and decay constant of the ðq" qÞ-pion together with the masses of r and u mesons are calculated in a chiral symmetric potential model of independent quarks, taking into account the corrections due to the possible residual interactions, such as quark-pion coupling arising out of the requirement of chiral symmetry and quark gluon coupling arising out of one-gluon-exchange, and that due to the spurious center-of-mass motion of the meson core. The effective potential representing phenomenologically the nonperturbative gluon interactions, including gluon self coupling, is chosen with equally mixed scalar and vector parts in a logarithmic form. The result obtained for the physical mass of ðq" qÞ-pion is consistent with that of the PCAC-pion, and the pion-decay constant reasonably agrees with experiment.PACS Nos: 12.40Aa, 12.40.Qq, 14.20.Dh Résumé : Nous calculons la masse et la constante de désintégration du système ðq" qÞ-pion, ainsi que les masses des mé-sons r et u dans un modèle avec potentiel à symétrie chirale pour quarks indépendants. Ce potentiel tient compte des corrections dues aux possibles interactions résiduelles comme le couplage quark-pion provenant de la symétrie chirale ou quark-gluon provenant des échanges à un gluon, ainsi que du mouvement parasite du centre de masse du coeur mésonique. Nous choisissons le potentiel effectif qui représente phénoménologiquement les interactions non perturbatives de gluons, incluant gluon-gluon, avec un mélange égal de parties scalaire et vecteur sous forme logarithmique. Le résultat obtenu pour la masse physique du système ðq" qÞ-pion est cohérente avec celle du PCAC-pion et la constante de désintégration agrée raisonnablement avec l'expérience.[Traduit par la Rédaction]

show abstract

Section: Resultssupporting

confidence: 70%

( q q ¯ ) -pion mass and decay constant in a relativistic independent-quark model

2009

View full text Add to dashboard Cite

show abstract

“…Table 7 displays the published experimental results concerning the contribution of the 0.630 − 0.958 GeV/c region to a µ (ππ). We first list the three important results from CMD-2 and SND; as we also use the data sets from OLYA and CMD [80], we also give at the line flagged by "OLD" our average using these data sets together with those from NA7 [111], TOF [112], M2N [113], DM1 [81], all collected before those from [75,76,77,78].…”

Section: 2mentioning

confidence: 99%

Upgraded breaking of the HLS model: a full solution to the τ−e + e − and ϕ decay issues and its consequences on g−2 VMD estimates

et al. 2012

View full text Add to dashboard Cite

The muon anomalous magnetic moment a μ and the hadronic vacuum polarization are examined using data analyzed within the framework of a suitably broken HLS model. The analysis relies on all available scan data samples and leaves provisionally aside the existing ISR data. Our HLS model based global fit approach allows for a better check of consistency between data sets and we investigate how results depend on different strategies which may be followed. Relying on global fit qualities, we find several acceptable solutions leading to ambiguities in the reconstructed value for (a μ ) th . Among these, the most conservative solution is a had,LO μ [HLS improved] = 687.72(4.63) × 10 −10 and (a μ ) th = 11 659 175.37(5.31) × 10 −10 corresponding to a 4.1σ significance for the difference a μ = (a μ ) exp − (a μ ) th . It is also shown that the various contributions accessible through the model yield uniformly a factor 2 improvement of their uncertainty. The breaking procedure implemented in the HLS model is an extension of the former procedure based on a mechanism defined by Bando, Kugo and Yamawaki (BKY). This yields a quite satisfactory simultaneous description of most e + e − annihilation channels up to and including the φ meson (and of a set of 10 (mostly radiative) decay widths of light mesons. It also allows to achieve the proof of consistency between the e + e − → π + π − annihilation and the τ ± → π ± π 0 ν decay and gives a solution to the reported problem concerning the measured partial width ratio Γ (φ → K + K − )/Γ (φ → K 0 K 0 ). Prospects for improving the VMD based estimates of a μ are emphasized. a

show abstract

“…In extension of our previous work [30], we here calculate the ππ phase shift and the pion EM formfactor, |F π | 2 , from our vector correlator and compare them to data [39][40][41][42], in Fig. 10.…”

Section: Vacuum Spectral Functions In the Vector And Axial-vectomentioning

confidence: 99%

Massive Yang–Mills for vector and axial-vector spectral functions at finite temperature

Hohler

Rapp

2016

Annals of Physics

View full text Add to dashboard Cite

The hadronic mechanism which leads to chiral symmetry restoration is explored in the context of the ρπa1 system using Massive Yang-Mills, a hadronic effective theory which governs their microscopic interactions. In this approach, vector and axial-vector mesons are implemented as gauge bosons of a local chiral gauge group. We have previously shown that this model can describe the experimentally measured vector and axial-vector spectral functions in vacuum. Here, we carry the analysis to finite temperatures by evaluating medium effects in a pion gas and calculating thermal spectral functions. We find that the spectral peaks in both channels broaden along with a noticeable downward mass shift in the a1 spectral peak and negligible movement of the ρ peak. The approach toward spectral function degeneracy is accompanied by a reduction of chiral order parameters, i.e., the pion decay constant and scalar condensate. Our findings suggest a mechanism where the chiral mass splitting induced in vacuum is burned off. We explore this mechanism and identify future investigations which can further test it.

show abstract

Measurement of the pion form factor in the time-like region for q2 values between 0.1 (GeV/c)2 and 0.18 (GeV/c)2

Abstract: The EM formfactor of the pion has been studied in the time-likeregion by measuring σ(e+e− → π+π−) normalized to σ(e+e− → μ+μ−). Results have been obtained for q2 down to the physical threshold

Cited by 98 publications

References 6 publications

( q q ¯ ) -pion mass and decay constant in a relativistic independent-quark model

( q q ¯ ) -pion mass and decay constant in a relativistic independent-quark model

Upgraded breaking of the HLS model: a full solution to the τ−e + e − and ϕ decay issues and its consequences on g−2 VMD estimates

Massive Yang–Mills for vector and axial-vector spectral functions at finite temperature

Contact Info

Product

Resources

About