Dispersive evaluation of the inner radiative correction in neutron and nuclear 
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Seng, Chien-Yeah; Gorchtein, Mikhail; Ramsey-Musolf, Michael J.

doi:10.1103/physrevd.100.013001

Cited by 169 publications

(237 citation statements)

References 73 publications

(120 reference statements)

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“…Notice that the last two terms are equal-time commutators that satisfy the current algebra relation (9). Therefore, through an identical derivation as before, one obtains the following splitting for the electromagnetic radiative correction to F µ Kπ into two-point and three-point functions:…”

Section: Bramentioning

confidence: 91%

A new theory framework for the electroweak radiative corrections in Kl3 decays

Seng

Galviz

Meißner

2020

J. High Energ. Phys.

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We propose a new theory framework to study the electroweak radiative corrections in K l3 decays by combining the classic current algebra approach with the modern effective field theory. Under this framework, the most important O(G F α) radiative corrections are described by a single tensor T µν involving the time-ordered product between the charged weak current and the electromagnetic current, and all remaining pieces are calculable order-by-order in Chiral Perturbation Theory. We further point out a special advantage in the K 0 l3 channel that it suffers the least impact from the poorly-constrained low energy constants. This finding may serve as a basis for a more precise extraction of the matrix element V us in the future.

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Section: Bramentioning

confidence: 91%

A new theory framework for the electroweak radiative corrections in Kl3 decays

Seng

Galviz

Meißner

2020

J. High Energ. Phys.

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“…The hadronic uncertainty of the forward γZ-box correction has recently raised a significant interest [28][29][30][31][32][33][34][35][36][37][38][39][40] in the context of a precision determination of the weak mixing angle with parity-violating electron scattering [41,42]. Similarly, recent works on reducing hadronic and nuclear uncertainties of the γWbox correction [43][44][45][46][47] prove central in extracting the V ud element of the Cabibbo-Kobayashi-Maskawa (CKM) matrix and testing the CKM unitarity, a sensitive probe of the SM extensions [48]. Experimental observables explicitly sensitive to the TPE mechanism are instrumental in developing a dispersion-theoretical framework for TPE.The lepton-proton scattering amplitude in presence of TPE can be parameterized in terms of six generalized form factorsG E (Q 2 , ε),G M (Q 2 , ε) andF i (Q 2 , ε), i = 3, ..., 6 [49], where Q 2 is the negative four-momentum transfer squared, and ε = (1 + 2(1 + Q 2 4M 2 ) tan 2 θ 2 ) −1 , with M and θ being the nucleon mass and the lepton scattering angle, respectively.…”

mentioning

confidence: 99%

Study of Two-Photon Exchange via the Beam Transverse Single Spin Asymmetry in Electron-Proton Elastic Scattering at Forward Angles over a Wide Energy Range

Gou¹,

Arvieux²,

Aulenbacher³

et al. 2020

Phys. Rev. Lett.

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We report on a new measurement of the beam transverse single spin asymmetry in electron-proton elastic scattering, A ep ⊥ , at five beam energies from 315.1 MeV to 1508.4 MeV and at a scattering angle of 30 • < θ < 40 • . The covered Q 2 values are 0.032, 0.057, 0.082, 0.218, 0.613 (GeV/c) 2 . The measurement clearly indicates significant inelastic contributions to the two-photon-exchange (TPE) amplitude in the low-Q 2 kinematic region. No theoretical calculation is able to reproduce our result. Comparison with a calculation based on unitarity, which only takes into account elastic and πN inelastic intermediate states, suggests that there are other inelastic intermediate states such as ππN, KΛ and ηN. Covering a wide energy range, our new high-precision data provide a benchmark to study those intermediate states.PACS numbers: 13.60. Fz, 11.30.Er, 13.40.Gp As a probe of hadron structure, electron scattering has two advantages: the structurelessness of the electron and the smallness of the electromagnetic coupling (α ≈ 1/137). The small coupling allows to expand the scattering amplitude in powers of α and to interpret experiments within the one-photon-exchange (Born) approximation. This leading order approximation enables a straightforward extraction of the electromagnetic form factors with the Rosenbluth separation technique [1]. For a precise extraction of the form factors it is necessary to include higher order quantum corrections [2,3]. Importantly, most of those corrections do not alter the Rosenbluth formula in that they contribute an overall factor to the cross section.The contribution that is expected to break this pattern [4,5] is the two-photon-exchange (TPE) diagram depicted in Fig. 1. For a long time the TPE effects have eluded direct experimental searches [6][7][8]. The situation changed when a striking discrepancy between the Rosenbluth separation [9, 10] and the polarization transfer [11?-13] data on the proton form factor ratio µ p G E /G M was observed. To evaluate the TPE corrections one needs to model the doubly-virtual Compton scattering (VVCS) in the most general kinematics. This involves calculating the two-current correlator with inclusive hadronic intermediate states. The full account of the inclusive intermediate states contribution can be made in the limited nearforward kinematics [15]. Beyond the forward kinematics, it is only possible to account for the elastic [16][17][18][19] or the pion-nucleon (πN) [20] intermediate state contributions.The theoretical framework for calculating the TPE contributions plays an important role in evaluating the two-boson-exchange corrections to precision low-energy tests of the Standard Model (SM) in the electroweak sector. The proton polarizability contribution to the fine structure of light muonic atoms stems from the TPE diagram and is a substantial ingredient [21] in the proton radius puzzle, the 7σ discrepancy in the value of the proton charge radius extracted from hydrogen spectroscopy [22] and electron-proton (ep) scattering [23] on one hand, an...

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“…[42]). In addition, there is a recent claim that the size of the radiative corrections to neutron β decay needed in the evaluation of F A 1 was underestimated in previous analysis' [43,44] calling into question the previously determined values of F A 1 . The present situation thus calls for an independent measurement of F A 1 which, in addition, does not depend on the value of V ud .…”

Section: Helicity and Invariant Amplitudesmentioning

confidence: 99%

A new angle on an old problem: helicity approach to neutron beta decay in the Standard Model

2019

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We elaborate on the dichotomy between the description of the semileptonic decays of heavy hadrons on the one hand and the semileptonic decays of light hadrons such as neutron β decays on the other hand. For example, almost without exception the semileptonic decays of heavy baryons are described in cascade fashion as a sequence of two two-body decays B1 → B2 + W off−shell and W off−shell → ℓ+ν ℓ whereas neutron β decays are analyzed as true three-body decays n → p+e − +νe. Within the cascade approach it is possible to define a set of seven angular observables for polarized neutron β decays as well as the longitudinal, transverse and normal polarization of the decay electron. We determine the dependence of the observables on the usual vector and axial vector form factors. In order to be able to assess the importance of recoil corrections we expand the rate and the q 2 averages of the observables up to NLO and NNLO in the recoil parameter δ = (Mn − Mp)/(Mn + Mp) = 0.689 · 10 −3 . Remarkably, we find that the rate and three of the four parity conserving polarization observables that we analyze are protected from NLO recoil corrections when the second class current contributions are set to zero.

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Dispersive evaluation of the inner radiative correction in neutron and nuclear β decay

Cited by 169 publications

References 73 publications

A new theory framework for the electroweak radiative corrections in Kl3 decays

A new theory framework for the electroweak radiative corrections in Kl3 decays

Study of Two-Photon Exchange via the Beam Transverse Single Spin Asymmetry in Electron-Proton Elastic Scattering at Forward Angles over a Wide Energy Range

A new angle on an old problem: helicity approach to neutron beta decay in the Standard Model

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