New developments in FeynCalc 9.0

Shtabovenko, Vladyslav; Mertig, R.; Orellana, F.

doi:10.1016/j.cpc.2016.06.008

Cited by 833 publications

(634 citation statements)

References 127 publications

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“…However, due to parity conservation and with our convention for the polarization vectors, we have the relation 73) which implies that only 3 2 −1 2 + 1 = 5 amplitudes are independent:…”

Section: Helicity Amplitudes and Partial-wave Expansionmentioning

confidence: 99%

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Dispersion relation for hadronic light-by-light scattering: two-pion contributions

Colangelo

Hoferichter

Procura

et al. 2017

J. High Energ. Phys.

362

257

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In this third paper of a series dedicated to a dispersive treatment of the hadronic light-by-light (HLbL) tensor, we derive a partial-wave formulation for two-pion intermediate states in the HLbL contribution to the anomalous magnetic moment of the muon (g − 2) µ , including a detailed discussion of the unitarity relation for arbitrary partial waves. We show that obtaining a final expression free from unphysical helicity partial waves is a subtle issue, which we thoroughly clarify. As a by-product, we obtain a set of sum rules that could be used to constrain future calculations of γ * γ * → ππ. We validate the formalism extensively using the pion-box contribution, defined by two-pion intermediate states with a pion-pole left-hand cut, and demonstrate how the full known result is reproduced when resumming the partial waves. Using dispersive fits to high-statistics data for the pion vector form factor, we provide an evaluation of the full pion box, a π-box µ = −15.9(2)×10 −11 . As an application of the partial-wave formalism, we present a first calculation of ππ-rescattering effects in HLbL scattering, with γ * γ * → ππ helicity partial waves constructed dispersively using ππ phase shifts derived from the inverse-amplitude method. In this way, the isospin-0 part of our calculation can be interpreted as the contribution of the f 0 (500) to HLbL scattering in (g − 2) µ . We argue that the contribution due to charged-pion rescattering implements corrections related to the corresponding pion polarizability and show that these are moderate. Our final result for the sum of pion-box contribution and its S-wave rescattering corrections reads a π-box µ + a ππ,π-pole LHC µ,J=0 = −24(1) × 10 −11 .

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“…However, due to parity conservation and with our convention for the polarization vectors, we have the relation 73) which implies that only 3 2 −1 2 + 1 = 5 amplitudes are independent:…”

Section: Helicity Amplitudes and Partial-wave Expansionmentioning

confidence: 99%

“…Arguably the most important result of this paper, especially in view of future applications and generalizations, concerns the derivation of theΠ i functions, which allows us to establish 5 In this notebook, we make use of FeynCalc [72,73].…”

Section: Summary Of the Formalismmentioning

confidence: 99%

Dispersion relation for hadronic light-by-light scattering: two-pion contributions

Colangelo

Hoferichter

Procura

et al. 2017

J. High Energ. Phys.

362

257

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“…The calculations go as follows. Traces are performed with FeynCalc package [11]. The resulting expression is a linear combination of fractions with the numerator containing powers of k 2 , q 2 , k t, and k q, while q t vanishes.…”

Section: Introductionmentioning

confidence: 99%

One-loop binding corrections to the electron g factor

Pachucki

Puchalski

2017

Phys. Rev. A

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“…We are also grateful to Vladyslav Shtabovenko for providing useful tools to check the loop integrals [46,47].…”

Section: Acknowledgmentsmentioning

confidence: 99%

CP asymmetry in heavy Majorana neutrino decays at finite temperature: the hierarchical case

Biondini

Brambilla

Vairo

2016

J. High Energ. Phys.

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Abstract:We consider the simplest realization of leptogenesis with one heavy Majorana neutrino species much lighter than the other ones. In this scenario, when the temperature of the early universe is smaller than the lightest Majorana neutrino mass, we compute at first order in the Standard Model couplings and, for each coupling, at leading order in the termperature the CP asymmetry in the decays of the lightest neutrino into leptons and anti-leptons. We perform the calculation using a hierarchy of two effective field theories organized as expansions in the inverse of the heavy-neutrino masses. In the ultimate effective field theory, leading thermal corrections proportional to the Higgs self coupling and the gauge couplings are encoded in one single operator of dimension five, whereas corrections proportional to the top Yukawa coupling are encoded in four operators of dimension seven, which we compute.

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New developments in FeynCalc 9.0

Cited by 833 publications

References 127 publications

Dispersion relation for hadronic light-by-light scattering: two-pion contributions

Dispersion relation for hadronic light-by-light scattering: two-pion contributions

One-loop binding corrections to the electron g factor

CP asymmetry in heavy Majorana neutrino decays at finite temperature: the hierarchical case

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