Measurement of Parity Nonconservation in<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>pp</mml:mi></mml:math>Scattering at 45 MeV

Balzer, R.; Henneck, R.; Jacquemart, Ch.; Lang, J.; Simonius, M.; Haeberli, W.; Weddigen, Ch.; Reichart, W.; Jaccard, Samuel L.

doi:10.1103/physrevlett.44.699

Cited by 85 publications

(33 citation statements)

References 8 publications

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“…The data from Refs. [1][2][3] were analyzed in Ref. [42], resulting in the constraints on A SP and A P D shown in Fig.…”

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confidence: 99%

“…All four contribute to pp scattering. The pp asymmetry has been measured at 15 [1], 45 [2], and 221 MeV [3]. In the main, the first two experiments constrain the PVinduced mixing between 1 S 0 -and 3 P 0 -waves, while the third constrains mixing between 3 P 2 -and 1 D 2 -waves.…”

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confidence: 99%

“…There are also parity-violating (PV) pp interactions, which manifest the presence of weak interactions between the quarks inside each proton. Measurements of longitudinal beam asymmetries ∼ 10 −7 at Bonn [1], PSI [2], and TRIUMF [3] demonstrate that PV nucleon-nucleon (NN) forces exist. PV in NN systems is also probed via an asymmetry in the reaction np → dγ [4,5].…”

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confidence: 99%

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Parity-Violating Nucleon-Nucleon Force in the1/NcExpansion

2015

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Several experimental investigations have observed parity violation in nuclear systems-a consequence of the weak force between quarks. We apply the 1/Nc expansion of QCD to the P-violating T-conserving component of the nucleon-nucleon (NN) potential. We show there are two leadingorder operators, both of which affect pp scattering at order Nc. We find an additional four operators at order N 0 c sin 2 θW and six at O(1/Nc). Pion exchange in the PV NN force is suppressed by 1/Nc and sin 2 θW , providing a quantitative explanation for its non-observation up to this time. The large-Nc hierarchy of other PV NN force mechanisms is consistent with estimates of the couplings in phenomenological models. The PV observed in pp scattering data is compatible with natural values for the strong and weak coupling constants: there is no evidence of fine tuning. The strong-nuclear and electromagnetic forces play the most prominent role in proton-proton (pp) scattering. There are also parity-violating (PV) pp interactions, which manifest the presence of weak interactions between the quarks inside each proton. Measurements of longitudinal beam asymmetries ∼ 10 and TRIUMF [3] demonstrate that PV nucleon-nucleon (NN) forces exist. PV in NN systems is also probed via an asymmetry in the reaction np → dγ [4,5]. And ab initio calculations of few-nucleon systems allow us to take models of the PV NN force and predict, e.g., the longitudinal asymmetry in 3 He( n, p) 3 H [6], which is soon to be measured [7]. Nuclear parity violation is also observed in, e.g., the radiative decay of the first excited state of 19 F, but there theoretical uncertainties in the relationship between the observable and the model of the PV NN force are harder to quantify. Much work has gone into constraining the PV NN force from a variety of nuclear experiments, see Refs. [8,9] for recent reviews.The prevailing paradigm in such analyses is based on single-meson exchange between nucleons, most commonly in the framework developed by Desplanques, Donoghue, and Holstein (DDH) [10]. The quantum numbers of the exchanged mesons determine the operator structures that contribute, while operator coefficients involve products of strong and weak meson-nucleonnucleon coupling constants. In this paper we show that Standard Model (SM) couplings and the 1/N c expansion of QCD predict the operators, and the sizes of the associated coefficients, which appear in the PV NN potential.An alternative framework-suitable for studying PV at very low energies-that systematizes pioneering studies [11,12] has recently emerged [13][14][15], but has, as yet, been applied to far fewer experiments. The extension of chiral perturbation theory to few-nucleon systems, χEFT [16] has also been invoked [17][18][19][20][21]. In χEFT the one-pion-exchange piece of the PV NN force dominates, with all other effects suppressed by two orders in the chiral expansion.One-pion exchange gives the long-distance parityconserving potential, and drives many of the properties of light nuclei. But, thus far, experiment...

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“…The data from Refs. [1][2][3] were analyzed in Ref. [42], resulting in the constraints on A SP and A P D shown in Fig.…”

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confidence: 99%

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confidence: 99%

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confidence: 99%

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Parity-Violating Nucleon-Nucleon Force in the1/NcExpansion

2015

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“…It has been over half a century since Lee and Yang first suggested the possibility of parity non-conservation in the weak interaction [45], which was confirmed expermentially shortly thereafter by Wu et al [46][47][48][49][50]. Modern day experimental [51][52][53][54][55][56][57][58][59][60] and theoretical [61][62][63][64][65] studies have given attention to parity violating two-nucleon processes, where the strong interactions are most precisely understood. These include proton-neutron fusion, p + n → d + γ, and elastic proton scattering,…”

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confidence: 99%

Relativistic, model-independent, multichannel 2→2 transition amplitudes in a finite volume

2016

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We derive formalism for determining 2 + J → 2 infinite-volume transition amplitudes from finitevolume matrix elements. Specifically, we present a relativistic, model-independent relation between finite-volume matrix elements of external currents and the physically observable infinite-volume matrix elements involving two-particle asymptotic states. The result presented holds for states composed of two scalar bosons. These can be identical or non-identical and, in the latter case, can be either degenerate or non-degenerate. We further accommodate any number of strongly-coupled two-scalar channels. This formalism will, for example, allow future lattice QCD calculations of the ρ-meson form factor, in which the unstable nature of the ρ is rigorously accommodated.

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“…A number of PV observables in two-nucleon systems can in principle be used to constrain the PV part of the nucleon-nucleon interaction. In addition to proton-proton scattering [6][7][8][9], a particularly prominent example is the photon angular asymmetry A γ in the capture of polarized neutrons on unpolarized protons, which in terms of the traditional meson exchange models provides information on the PV pion-nucleon coupling. The NPDGamma experiment at Oak Ridge National Laboratory's Spallation Neutron Source is currently determining this asymmetry with the aim of significantly improving on previous results [10].…”

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Energy dependence of the parity-violating asymmetry of circularly polarized photons indγ⃗→npin pionless effective field theory

Vanasse

Schindler

2014

Phys. Rev. C

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We calculate the energy dependence of the asymmetry in the cross sections for circularly polarized photons on an unpolarized deuteron target in d γ → np in pionless effective field theory. By matching the parity-violating low-energy constants to different sets of corresponding model parameters we obtain estimates for the asymmetry. In addition we calculate a possible figure of merit for the asymmetry in order to assess the preferred photon energy at which to perform a possible future experiment at a high-intensity photon source. *

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Measurement of Parity Nonconservation inppScattering at 45 MeV

Cited by 85 publications

References 8 publications

Parity-Violating Nucleon-Nucleon Force in the1/NcExpansion

Parity-Violating Nucleon-Nucleon Force in the1/NcExpansion

Relativistic, model-independent, multichannel 2→2 transition amplitudes in a finite volume

Energy dependence of the parity-violating asymmetry of circularly polarized photons indγ⃗→npin pionless effective field theory

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