Charge Symmetry Breaking in<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>n</mml:mi><mml:mi>p</mml:mi><mml:mo>→</mml:mo><mml:mi>d</mml:mi><mml:msup><mml:mi>π</mml:mi><mml:mn>0</mml:mn></mml:msup></mml:math>

Opper, A. K.; Korkmaz, E.; Hutcheon, D. A.; Abegg, R.; Davis, C. A.; Finlay, R.W.; Green, P. W.; Greeniaus, L.G.; Jordán, D.; Niskanen, J.A.; O’Rielly, G. V.; Porcelli, T. A.; Reitzner, S. D.; Walden, P.; Yen, S.

doi:10.1103/physrevlett.91.212302

Cited by 54 publications

(19 citation statements)

References 18 publications

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“…In a first step a sum of Monte Carlo simulated distributions for each contribution from the partial wave decomposition (coefficients A 0 to A 6 ) and from the quasifree model (coefficient (−15.0 ± 0.2) × 10 4 μb/GeV 5 σ qf A 7 (1.108 ± 0.003) μb A 7 ) was fitted to the uncorrected, single differential spectra. The result served as input for the Monte Carlo simulation finally used to determine the acceptance correction.…”

Section: Resultsmentioning

confidence: 99%

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Investigation of thedd→3Henπ0reaction with the FZ Jülich WASA-at-COSY facility

Adlarson¹,

Augustyniak²,

Bardan³

et al. 2013

Phys. Rev. C

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An exclusive measurement of the dd → 3 Henπ 0 reaction was carried out at a beam momentum of p d = 1.2 GeV/c using the WASA-at-COSY facility. Information on the total cross section as well as differential distributions was obtained. The data are described by a phenomenological approach based on a combination of a quasifree model and a partial wave expansion for the three-body reaction. The total cross section is found to be σ tot = (2.89 ± 0.01 stat ± 0.06 sys ± 0.29 norm ) μb. The contribution of the quasifree processes (with the beam or target neutron being a spectator) accounts for 38% of the total cross section and dominates the differential distributions in specific regions of phase space. The remaining part of the cross section can be described by a partial wave decomposition indicating the significance of p-wave contributions in the final state.

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Section: Resultsmentioning

confidence: 99%

“…At the same time information on CSB in np → dπ 0 manifesting itself in a forward-backward asymmetry became available [7]. These data triggered advanced theoretical calculations within effective field theory, providing the opportunity to investigate the influence of the quark masses in nuclear physics [8,9].…”

Section: Introductionmentioning

confidence: 99%

Investigation of thedd→3Henπ0reaction with the FZ Jülich WASA-at-COSY facility

Adlarson¹,

Augustyniak²,

Bardan³

et al. 2013

Phys. Rev. C

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“…The larger central value suggests a larger contribution to M p − M n from m d − m u , consistent with expectations from lattice QCD, thus impacting the phenomenology of Refs. [22][23][24][25][26][27]. With plausible model assumptions and additional input from lattice QCD, this knowledge can be used to provide a competitive estimate of the nucleon isovector magnetic polarizability, albeit still with a 100% uncertainty.…”

mentioning

confidence: 99%

“…While the lattice calculations of m d − m u effects are robust, the contributions from electromagnetism are less mature and suffer from larger systematics, due in large part to the disparity between the photon mass and a typical hadronic scale. Improved knowledge of m d − m u and its effects in nucleons will enhance the ability to use effective field theory to compute a variety of isospin-violating (charge asymmetric) effects in nuclear reactions [7,[22][23][24][25][26][27]]. …”

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confidence: 99%

Electromagnetic Self-Energy Contribution toMp−Mnand the Isovector Nucleon Magnetic Polarizability

2012

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We update the determination of the isovector nucleon electromagnetic self-energy, valid to leading order in QED. A technical oversight in the literature concerning the elastic contribution to Cottingham's formula is corrected and modern knowledge of the structure functions is used to precisely determine the inelastic contribution. We find δM γ p−n = 1.30(03)(47) MeV. The largest uncertainty arises from a subtraction term required in the dispersive analysis, which can be related to the isovector magnetic polarizability. With plausible model assumptions, we can combine our calculation with additional input from lattice QCD to constrain this polarizability as: βp−n = −0.87(85) × 10 −4 fm 3 .PACS numbers: 13.40. Dk, 13.40.Ks, 13.60.Fz, 14.20.Dh Given only electrostatic forces, one would predict that the proton is more massive than the neutron but the opposite actually occurs [1-3]:Before we knew of quarks and gluons there were many attempts to explain this contradiction, see Ref.[4] for a review. We now know there are two sources of isospin breaking in the standard model, the masses of the up and down quarks as well as the electromagnetic interactions between quarks governed by the charge operator. The effects of the mass difference between down and up quarks are larger and of the opposite sign than those of electromagnetic effects, see the reviews [5][6][7]. The net result of the quark mass difference and electromagnetic effects is well known, Eq. (1), but our ability to disentangle the contributions from these two sources remains poorly constrained. In contrast, lattice QCD calculations have matured significantly. There are now calculations performed with the light quark masses at or near their physical values [8][9][10][11][12], reproducing the ground state hadron spectrum within a few percent. These advances have allowed for calculations to begin including explicit isospin breaking effects from both the quark masses [13][14][15][16][17] and electromagnetism [15,[18][19][20][21]. While the lattice calculations of m d − m u effects are robust, the contributions from electromagnetism are less mature and suffer from larger systematics, due in large part to the disparity between the photon mass and a typical hadronic scale. Improved knowledge of m d − m u and its effects in nucleons will enhance the ability to use effective field theory to compute a variety of isospin-violating (charge asymmetric) effects in nuclear reactions [7,[22][23][24][25][26][27]].An application [28] of the Cottingham sum rule [29], which relates the electromagnetic self-energy of the nucleon to measured elastic and inelastic cross sections, gives the result δM γ p−n = 0.76 ± 0.30 MeV. Given the high present interest in the precise value of δM γ p−n and its many possible implications, it is worthwhile to revisit this result. Many high quality electron scattering experiments have been performed since 1975 and there have also been theoretical advances. The central aim of this work is to provide a modern, robust evaluation of δM γ p−n . We wil...

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“…The n·p d·π 0 experiment [8] made use of the 279.5-MeV proton beam at TRIUMF. The proton beam hit a 7 Li neutron production target in the CHARGEX Facility.…”

Section: The N+p D+π 0 Reactionmentioning

confidence: 99%

Charge symmetry breaking in the few nucleon system

Stephenson¹

2005

AIP Conference Proceedings

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This report discusses two recent experiments that have produced new results in charge symmetry breaking, the fore-aft cross section asymmetry in n · p d · π 0 and the observation of the isospin-forbidden d · d 4 He · π 0 reaction. These experiments are being analyzed using effective field theory that establishes a connection to the quark-level processes that generate all charge symmetry breaking: the down-up quark mass difference and electromagnetic effects among the quarks. 31This article is copyrighted as indicated in the article. Reuse of AIP content is subject to the terms at: http://scitation.aip.org/termsconditions. Downloaded

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Charge Symmetry Breaking innp→dπ0

Cited by 54 publications

References 18 publications

Investigation of thedd→3Henπ0reaction with the FZ Jülich WASA-at-COSY facility

Investigation of thedd→3Henπ0reaction with the FZ Jülich WASA-at-COSY facility

Electromagnetic Self-Energy Contribution toMp−Mnand the Isovector Nucleon Magnetic Polarizability

Charge symmetry breaking in the few nucleon system

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