Test of Isospin Symmetry via Low-Energy<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mmultiscripts><mml:mi mathvariant="normal">H</mml:mi><mml:mprescripts /><mml:none /><mml:mn>1</mml:mn></mml:mmultiscripts><mml:mo stretchy="false">(</mml:mo><mml:msup><mml:mi>π</mml:mi><mml:mo>−</mml:mo></mml:msup><mml:mo>,</mml:mo><mml:msup><mml:mi>π</mml:mi><mml:mn>0</mml:mn></mml:msup><mml:mo stretchy="false">)</mml:mo><mml:mi>n</mml:mi></mml:math>Charge Exchange

Yang, Jia; Tp, Gorringe; Hasinoff,; Ma, Kovash; Ojha, Mamta U.; Mm, Pavan; Tripathi, S.; Pa, Zołnierczuk

doi:10.1103/physrevlett.101.102301

Cited by 6 publications

(3 citation statements)

References 14 publications

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“…[22,23], which are incompatible with the modern pionic-atom data. Independent constraints from experiment are provided by low-energy πN cross sections, including more recent data on both the elastic reactions [47][48][49] and the charge exchange [50][51][52][53], and a global analysis of low-energy data in the Roy-Steiner framework leads to σ πN = 58 (5) MeV [37], in perfect agreement with the pionic-atom result. In contrast, so far lattice QCD calculations [54][55][56][57][58][59][60][61][62] have favored low values σ πN ≈ 40 MeV (with the exception of Ref.…”

Section: Introductionmentioning

confidence: 62%

The pion-nucleon sigma term from lattice QCD

Gupta,

Park,

Hoferichter

et al. 2021

Preprint

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We present an analysis of the pion-nucleon σ-term, σπN , using six ensembles with 2+1+1-flavor highly improved staggered quark action generated by the MILC collaboration. The most serious systematic effect in lattice calculations of nucleon correlation functions is the contribution of excited states. We estimate these using chiral perturbation theory (χPT), and show that the leading contribution to the isoscalar scalar charge comes from N π and N ππ states. Therefore, we carry out two analyses of lattice data to remove excited-state contamination, the standard one and a new one including N π and N ππ states. We find that the standard analysis gives σπN = 40.4(4.7) MeV, consistent with previous lattice calculations, while the χPT-motivated analysis gives σπN = 61.6(6.4) MeV, which is consistent with phenomenological values obtained using πN scattering data. Our data on one physical pion mass ensemble was crucial for exposing this difference, therefore, calculations on additional physical mass ensembles are needed to confirm our result and resolve the tension between lattice QCD and phenomenology.

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Section: Introductionmentioning

confidence: 62%

The pion-nucleon sigma term from lattice QCD

Gupta,

Park,

Hoferichter

et al. 2021

Preprint

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show abstract

“…Our uncertainty estimates, derived from the Hessian at the fit minimum, do not produce the very large O(1) uncertainties as observed in the GW fit. However, especially for the charge-exchange reaction, some normalizations still carry sizable uncertainties, which may be related to inconsistencies in the data base or underestimated experimental 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 errors already noticed in [68,69].…”

Section: Page 8 Of 17 Author Submitted Manuscript -Jphysg-101976r3mentioning

confidence: 99%

“…as observed in the GW fit. However, especially for the charge-exchange reaction, some normalizations still carry sizable uncertainties, which may be related to inconsistencies in the data base or underestimated experimental errors already noticed in [68,69].…”

Section: Fit To the Pion-nucleon Data Basementioning

confidence: 99%

Extracting the σ-term from low-energy pion-nucleon scattering

Elvira

Hoferichter

Kubis³

et al. 2017

J. Phys. G: Nucl. Part. Phys.

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Abstract. We present an extraction of the pion-nucleon (πN ) scattering lengths from low-energy πN scattering, by fitting a representation based on RoySteiner equations to the low-energy data base. We show that the resulting values confirm the scattering-length determination from pionic atoms, and discuss the stability of the fit results regarding electromagnetic corrections and experimental normalization uncertainties in detail. Our results provide further evidence for a large πN σ-term, σ πN = 58(5) MeV, in agreement with, albeit less precise than, the determination from pionic atoms.

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Differential cross sections of the charge-exchange reactionπ−p→π0nin the momentum range from103
Mekterović¹,
Supek²,
Abaev³
et al. 2009
Phys. Rev. C
6
0
6
0
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Differential cross sections of the charge-exchange reaction π − p → π 0 n in the momentum range from 103 to 178 MeV/c Measured values of the differential cross sections for pion-nucleon charge exchange, π − p → π 0 n, are presented for π − momenta of 103, 112, 120, 130, 139, 152, and 178 MeV/c. Complete angular distributions were obtained by using the Crystal Ball detector at the Alternating Gradient Synchrotron at Brookhaven National Laboratory. Statistical uncertainties of the differential cross sections vary from 3% to 6% in the backward angle region, and from 6% to about 20% in the forward region with the exception of the two most forward angles. The systematic uncertainties are estimated to be about 3% for all momenta. I. INTRODUCTIONThere are three experimentally accessible scattering channels in the πN system: π + p → π + p and π − p → π − p elastic scattering, and the π − p → π 0 n charge-exchange reaction (CEX). Precise data for all three channels are needed to obtain an accurate description of the πN system via a consistent and complete set of scattering amplitudes. In that regard, the least satisfying situation is in the region below 100 MeV π − kinetic energy where the experimental database for CEX is quite limited. On the other hand, the low-energy region is very interesting because isospin symmetry-breaking effects may be visible there. Furthermore, low-energy data have a strong impact on extrapolations of scattering amplitudes to the nonphysical region, and this extrapolation is needed to obtain important physical quantities such as the πN σ term.Isospin symmetry is one of the key concepts in hadronic physics. Thus, it is very important to measure precisely small symmetry-breaking effects coming from both the up-down quark mass difference and the electromagnetic interaction. In the πN system, one such isospin-breaking effect is a departure from the so-called triangle relation

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Test of Isospin Symmetry via Low-EnergyH1(π−,π0)nCharge Exchange

Cited by 6 publications

References 14 publications

The pion-nucleon sigma term from lattice QCD

The pion-nucleon sigma term from lattice QCD

Extracting the σ-term from low-energy pion-nucleon scattering

Differential cross sections of the charge-exchange reactionπ−p→π0nin the momentum range from103
Mekterović¹,
Supek²,
Abaev³
et al. 2009
Phys. Rev. C
6
0
6
0
View full text Add to dashboard Cite

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Test of Isospin Symmetry via Low-EnergyH1(π−,π0)nCharge Exchange

Cited by 6 publications

References 14 publications

The pion-nucleon sigma term from lattice QCD

The pion-nucleon sigma term from lattice QCD

Extracting the σ-term from low-energy pion-nucleon scattering

Differential cross sections of the charge-exchange reactionπ−p→π0nin the momentum range from103Mekterović1, Supek2, Abaev3 et al. 2009Phys. Rev. C6060View full textAdd to dashboardCite

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Differential cross sections of the charge-exchange reactionπ−p→π0nin the momentum range from103
Mekterović¹,
Supek²,
Abaev³
et al. 2009
Phys. Rev. C
6
0
6
0
View full text Add to dashboard Cite