Electromagnetic Mass Difference of Pions

Das, T.; Guralnik, G. S.; Mathur, V.S.; Low, F. E.; Young, John

doi:10.1103/physrevlett.18.759

Cited by 441 publications

(348 citation statements)

References 12 publications

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“…Interestingly, there exists a simple dispersion relation for the electromagnetic pion mass difference in QCD [63][64][65]. In particular, in that case current four point functions can be reduced to two point functions using PCAC and current algebra.…”

Section: Jhep03(2012)046mentioning

confidence: 99%

Exploring T and S parameters in Vector Meson Dominance models of strong electroweak symmetry breaking

Orgogozo

Rychkov

2012

J. High Energ. Phys.

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Abstract:We revisit the electroweak precision tests for Higgsless models of strong EWSB. We use the Vector Meson Dominance approach and express S and T via couplings characterizing vector and axial spin-1 resonances of the strong sector. These couplings are constrained by the elastic unitarity and by requiring a good UV behavior of various formfactors. We pay particular attention to the one-loop contribution of resonances to T (beyond the chiral log), and to how it can improve the fit. We also make contact with the recent studies of Conformal Technicolor. We explain why the second Weinberg sum rule never converges in these models, and formulate a condition necessary for preserving the custodial symmetry in the IR.

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Section: Jhep03(2012)046mentioning

confidence: 99%

Exploring T and S parameters in Vector Meson Dominance models of strong electroweak symmetry breaking

Orgogozo

Rychkov

2012

J. High Energ. Phys.

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“…The computation of the vacuum polarization functions over the complete q 2 range allows the computation of the electromagnetic contribution to mass splitting between the charged and neutral pions [49],…”

Section: Pion Mass Splittingmentioning

confidence: 99%

Sparameter in QCD from domain wall fermions

et al. 2010

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We have computed the SU (2) Low Energy Constant l 5 and the mass splitting between charged and neutral pions from a lattice QCD simulation of n f = 2 + 1 flavors of Domain Wall Fermions at a scale of a −1 = 2.33 GeV. Relating l 5 to the S parameter in QCD we obtain a value of S(m H = 120 GeV) = 0.42(7), in agreement with previous determinations. Our result can be compared with the value of S from electroweak precision data which constrains strongly interacting models of new physics like Technicolor. This work in QCD serves as a test for the methods to compute the S parameter with Domain Wall Fermions in theories beyond the Standard Model. We also infer a value for the pion mass splitting in agreement with experiment.

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“…In this classic example, it is well known that C γ is determined by the same two-point function Π LR (Q 2 ) that we have already encountered [6], but contrary to F 0 or to L 10 , which describe its low-momentum behaviour, the identification of C γ involves an integral of Π LR (Q 2 ), weighted with the free photon propagator, over the whole range of momenta,…”

Section: A Classic Example Revisitedmentioning

confidence: 99%

“…(50) and ǫ γγ is the sign of the on-shell form factor c(0, 0) (for the notation, we refer to [30]; see in particular Eqs. (6) and (7) of that reference) describing the K 0 L → γγ decay. However, as also discussed in Ref.…”

Section: Decay Of Pseudoscalars Into Lepton Pairsmentioning

confidence: 99%

A new approach to weak amplitudes in large-Nc QCD

Knecht

Peris

Rafael

2000

Nuclear Physics B - Proceedings Supplements

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We report on some recent progress made in understanding weak matrix elements of mesons in the context of the next-to-leading order of the large-NC approximation to QCD. Specifically, we first use the example of the weak contributions to the π + − π 0 mass difference to exhibit how a systematic matching can be achieved analytically between short distances and long distances within our large-NC framework. We are then also able to compute matrix elements of the operator Q7, as they turn out to depend on the same QCD correlator as the previous pion mass difference. As a final example we determine the chiral counterterms governing the pseudoscalar decay into a lepton pair, where we briefly comment also on the special case KL → µ + µ − . This report covers the material presented by the authors in three separate talks at the QCD'99 conference in Montpellier.

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Electromagnetic Mass Difference of Pions

Cited by 441 publications

References 12 publications

Exploring T and S parameters in Vector Meson Dominance models of strong electroweak symmetry breaking

Exploring T and S parameters in Vector Meson Dominance models of strong electroweak symmetry breaking

Sparameter in QCD from domain wall fermions

A new approach to weak amplitudes in large-Nc QCD

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