Experimental status of the<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>π</mml:mi><mml:mi>π</mml:mi></mml:math>isoscalar<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>S</mml:mi></mml:math>wave at low energy:<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msub><mml:mi>f</mml:mi><mml:mn>0</mml:mn></mml:msub><mml:mo stretchy="false">(</mml:mo><mml:mn>600</mml:mn><mml:mo stretchy="false">)</mml:mo></mml:math>p

García‐Martín, R.; Peláez, J. R.; Ynduráin, Félix

doi:10.1103/physrevd.76.074034

Cited by 78 publications

(130 citation statements)

References 33 publications

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“…(iii) In KPY08 [3] we also considered Roy equations [9] for our amplitudes below K " K threshold. The UFD fits, where we had previously incorporated [6] the most reliable low energy data from K '4 decays to that date [8], satisfied Roy equations fairly well and the agreement was remarkably good once they were imposed into a new set of CFD. Since, in this work, we are going to consider a set of dispersion relations in addition to the dispersive constraints we have just described, our starting point will be the UFD set already obtained in KPY08, which we describe only very briefly in the next subsections, but explain in detail in Appendix A.…”

Section: The Unconstrained Fits To Data a Our Previous Workmentioning

confidence: 98%

“…The use of a conformal variable allows for a very rapid convergence-at most, two or three terms are needed in the expansion-so that each wave is represented by only three to five parameters, corresponding to the coefficients of the expansion and the position of the zeros and poles when we have found it convenient to factorize them explicitly [6]. We remark again that the use of a conformal expansion does not imply any model dependence.…”

Section: Parametrizations For S2 P D F and G Wavesmentioning

confidence: 99%

“…In general, for each paper of this series (or also in [6]), we have first obtained a set of phenomenological ''unconstrained'' fits to data (UFD), which was fairly consistent with the dispersive requirements. Next, starting from that UFD set, we obtained ''constrained'' fits to data (CFD) by imposing simultaneous fulfillment of dispersion relations.…”

Section: Introductionmentioning

confidence: 99%

“…Since Roy equations are written in terms of partial waves, they lead, if supplemented with further theoretical input from ChPT [13], to precise predictions for resonance poles like the much debated f 0 ð600Þ. Despite being listed with huge uncertainties in the Particle Data Book [14], several analyses using analytic methods or dispersive techniques with chiral constraints [6,15], as well as those using Roy equations [13], are in fair agreement about its pole position, around 450-i250 MeV. However, its nature remains controversial, since it might not be an ordinary meson [16].…”

Section: Introductionmentioning

confidence: 99%

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Pion-pion scattering amplitude. IV. Improved analysis with once subtracted Roy-like equations up to 1100 MeV

et al. 2011

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We improve our description of scattering data by imposing additional requirements on our previous fits, in the form of once-subtracted Roy-like equations, while extending our analysis up to 1100 MeV. We provide simple and ready to use parametrizations of the amplitude. In addition, we present a detailed description and derivation of these once-subtracted dispersion relations that, in the 450 to 1100 MeV region, provide an additional constraint which is much stronger than our previous requirements of forward dispersion relations and standard Roy equations. The ensuing constrained amplitudes describe the existing data with rather small uncertainties in the whole region from threshold up to 1100 MeV, while satisfying very stringent dispersive constraints. For the S0 wave, this requires an improved matching of the low and high energy parametrizations. Also for this wave we have considered the latest low energy K '4 decay results, including their isospin violation correction, and we have removed some controversial data points. These changes on the data translate into better determinations of threshold and subthreshold parameters which remove almost all disagreement with previous chiral perturbation theory and Roy equation calculations below 800 MeV. Finally, our results favor the dip structure of the S0 inelasticity around the controversial 1000 MeV region.

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Section: The Unconstrained Fits To Data a Our Previous Workmentioning

confidence: 98%

Section: Parametrizations For S2 P D F and G Wavesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Pion-pion scattering amplitude. IV. Improved analysis with once subtracted Roy-like equations up to 1100 MeV

et al. 2011

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“…At this point it is important to note again that the sigma mass is not to be identified with the complex pole in the I = 0 s-wave channel of the pion-pion scattering amplitude at √ s (500 − i 300) MeV [106,107]. The σ boson in the ChNM model parametrizes part of the N N and πN s-wave interactions at short-distance.…”

Section: Mean-field Parameter Settingsmentioning

confidence: 99%

Functional renormalization group studies of nuclear and neutron matter

Drews

Weise

2017

Progress in Particle and Nuclear Physics

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Functional renormalization group (FRG) methods applied to calculations of isospinsymmetric and asymmetric nuclear matter as well as neutron matter are reviewed. The approach is based on a chiral Lagrangian expressed in terms of nucleon and meson degrees of freedom as appropriate for the hadronic phase of QCD with spontaneously broken chiral symmetry. Fluctuations beyond mean-field approximation are treated solving Wetterich's FRG flow equations. Nuclear thermodynamics and the nuclear liquid-gas phase transition are investigated in detail, both in symmetric matter and as a function of the proton fraction in asymmetric matter. The equations of state at zero temperature of symmetric nuclear matter and pure neutron matter are found to be in good agreement with advanced ab-initio many-body computations. Contacts with perturbative many-body approaches (in-medium chiral perturbation theory) are discussed. As an interesting test case, the density dependence of the pion mass in the medium is investigated. The question of chiral symmetry restoration in nuclear and neutron matter is addressed. A stabilization of the phase with spontaneously broken chiral symmetry is found to persist up to high baryon densities once fluctuations beyond mean-field are included. Neutron star matter including beta equilibrium is discussed under the aspect of the constraints imposed by the existence of two-solar-mass neutron stars.

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Interactions of two and three mesons including higher partial waves from lattice QCD

Blanton

Hanlon

Hörz

et al. 2021

J. High Energ. Phys.

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We study two- and three-meson systems composed either of pions or kaons at maximal isospin using Monte Carlo simulations of lattice QCD. Utilizing the stochastic LapH method, we are able to determine hundreds of two- and three-particle energy levels, in nine different momentum frames, with high precision. We fit these levels using the relativistic finite-volume formalism based on a generic effective field theory in order to determine the parameters of the two- and three-particle K-matrices. We find that the statistical precision of our spectra is sufficient to probe not only the dominant s-wave interactions, but also those in d waves. In particular, we determine for the first time a term in the three-particle K-matrix that contains two-particle d waves. We use three Nf = 2 + 1 CLS ensembles with pion masses of 200, 280, and 340 MeV. This allows us to study the chiral dependence of the scattering observables, and compare to the expectations of chiral perturbation theory.

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Experimental status of theππisoscalarSwave at low energy:f0(600)p

Cited by 78 publications

References 33 publications

Pion-pion scattering amplitude. IV. Improved analysis with once subtracted Roy-like equations up to 1100 MeV

Pion-pion scattering amplitude. IV. Improved analysis with once subtracted Roy-like equations up to 1100 MeV

Functional renormalization group studies of nuclear and neutron matter

Interactions of two and three mesons including higher partial waves from lattice QCD

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