Measurement of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si1.gif" overflow="scroll"><mml:mi>σ</mml:mi><mml:mo stretchy="false">(</mml:mo><mml:msup><mml:mi>e</mml:mi><mml:mo>+</mml:mo></mml:msup><mml:msup><mml:mi>e</mml:mi><mml:mo>−</mml:mo></mml:msup><mml:mo>→</mml:mo><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:mi>γ</mml:mi><mml:mo stretchy="false">(</mml:mo><mml:mi>γ</mml:mi><mml:mo stretchy="false">)</mml:mo

Ambrosino, F.; Antonelli, A.; Antonelli, M.; Archilli, F.; Bacci, C.; Beltrame, P.; Bencivenni, G.; Bertolucci, S.; Bini, C.; Bloise, C.; Bocchetta, S. S.; Bossi, F.; Branchini, P.; Campana, P.; Capon, G.; Capussela, T.; Ceradini, F.; Chi, S.; Chiefari, G.; Ciambrone, P.; Crucianelli, F.; Lucia, E. De; Santis, A. De; Simone, P. De; Zorzi, G. De; Denig, A.; Domenico, A. Di; Donato, C. Di; Falco, S. Di; Micco, B. Di; Doria, A.; Dreucci, M.; Felici, G.; Ferrari, A.; Ferrer, M. L.; Fiore, S.; Forti, C.; Franzini, P.; Gatti, C.; Gauzzi, P.; Giovannella, S.; Gorini, E.; Graziani, E.; Incagli, M.; Kluge, W.; Kulikov, V.; Lacava, F.; Lanfranchi, G.; Lee‐Franzini, J.; Leone, D.; Martemianov, M.; Martini, M.; Massarotti, P.; Mei, W.; Meola, S.; Miscetti, S.; Moulson, M.; Müller, S.; Murtas, F.; Napolitano, M.; Nguyen, F.; Palutan, M.; Pasqualucci, E.; Passeri, A.; Patera, V.; Perfetto, F.; Primavera, M.; Santangelo, P.; Saracino, G.; Sciascia, B.; Sciubba, A.; Sibidanov, A.; Spadaro, T.; Testa, M.; Tortora, L.; Valente, P.; Valeriani, B.; Venanzoni, G.; Versaci, R.; Xu, G. F.

doi:10.1016/j.physletb.2008.10.060

Cited by 173 publications

(116 citation statements)

References 27 publications

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“…This allows to cover, for a fixed value of the centre-of-mass energy of the e + e − collider and with the same detector conditions, a wide range of the spectrum of the hadronic final state. This type of measurement was first performed by the KLOE experiment, 20 where events with the ISR photon emitted along the beam-pipe were considered, using theory for the evaluation of the ISR effective luminosity. The BABAR experiment pioneered a luminosity-independent technique which consists in measuring the ratio of the cross sections 21,22 where large cancellations of systematic effects occur.…”

Section: Dispersion Relationsmentioning

confidence: 99%

Hadron Contribution to Vacuum Polarisation

Davier¹,

Hoecker²,

Malaescu³

et al. 2016

Advanced Series on Directions in High Energy Physics

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Precision tests of the Standard Theory require theoretical predictions taking into account higher-order quantum corrections. Among these vacuum polarisation plays a predominant role. Vacuum polarisation originates from creation and annihilation of virtual particle-antiparticle states. Leptonic vacuum polarisation can be computed from quantum electrodynamics. Hadronic vacuum polarisation cannot because of the non-perturbative nature of QCD at low energy. The problem is remedied by establishing dispersion relations involving experimental data on the cross section for e + e − annihilation into hadrons. This chapter sets the theoretical and experimental scene and reviews the progress achieved in the last decades thanks to more precise and complete data sets. Among the various applications of hadronic vacuum polarisation calculations, two are emphasised: the contribution to the anomalous magnetic moment of the muon, and the running of the fine structure constant α to the Z mass scale. They are fundamental ingredients to high precision tests of the Standard Theory.

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Section: Dispersion Relationsmentioning

confidence: 99%

Hadron Contribution to Vacuum Polarisation

Davier¹,

Hoecker²,

Malaescu³

et al. 2016

Advanced Series on Directions in High Energy Physics

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“…To correctly compute the dispersive integral, we have to take into account correlations between data sets. In the case of the KLOE data, there are non-negligible correlations with their previous data sets [16,17]. These correlations are correctly summarised in the covariance matrix in Ref.…”

Section: Update In Input Datamentioning

confidence: 56%

Hadronic Leading Order Contribution to the Muon g-2

Nomura

2018

EPJ Web Conf.

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Abstract. We calculate the Standard Model (SM) prediction for the muon anomalous magnetic moment. By using the latest experimental data for e + e − → hadrons as input to dispersive integrals, we obtain the values of the leading order (LO) and the next-to-leading-order (NLO) hadronic vacuum polarisation contributions as a had, LO VP µ = (693.27 ± 2.46) × 10 −10 and a had, NLO VP µ = (−9.82 ± 0.04) × 10 −10 , respectively. When combined with other contributions to the SM prediction, we obtain a µ (SM) = (11659182.05 ± 3.56) × 10 −10 , which is deviated from the experimental value by ∆a µ ≡ a µ (exp) − a µ (SM) = (27.05 ± 7.26) × 10 −10 . This means that there is a 3.7 σ discrepancy between the experimental value and the SM prediction. We also discuss another closely related quantity, the running QED coupling at the Z-pole, α(M 2 Z ). By using the same e + e − → hadrons data as input, our result for the 5-flavour quark contribution to the running QED coupling at the Z pole is ∆α (5) had (M 2 Z ) = (276.11 ± 1.11) × 10 −4 , from which we obtain α −1 (M 2 Z ) = 128.946 ± 0.015.

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“…3 [7,8,9]. However, the results of KLOE and BaBar differ, the discrepancy reaching 5% in some energy regions, far beyond the declared precision.…”

Section: Pos(cd15)013mentioning

confidence: 93%