The CONTRIBUTION OF THE LIGHT QUARK CONDENSATE TO THE ΠN SIGMA TERM

Gibbs, W. R.

doi:10.1142/s0217732303010995

Cited by 4 publications

(3 citation statements)

References 39 publications

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“…If no significant deviations from the phase shift analyses are observed, then alternative explanations for the large values of the sigma term from recent extractions [6] will have to be found. Several ideas have been put forward, questioning the extraction procedure from πp data [23], the equivalence of the (sigma) terms extracted from πp scattering and baryon masses [24], or the validity of the connection [4] of baryon masses and sigma term [25].…”

Section: Resultsmentioning

confidence: 99%

Low energy analyzing powers in pion–proton elastic scattering

et al. 2004

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Analyzing powers of pion-proton elastic scattering have been measured at PSI with the Low Energy Pion Spectrometer LEPS as well as a novel polarized scintillator target. Angular distributions between 40 and 120 deg (c.m.) were taken at 45.2, 51.2, 57.2, 68.5, 77.2, and 87.2 MeV incoming pion kinetic energy for π + p scattering, and at 67.3 and 87.2 MeV for π − p scattering. These new measurements constitute a substantial extension of the polarization data base at low energies. Predictions from phase shift analyses are compared with the experimental results, and deviations are observed at low energies.

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Section: Resultsmentioning

confidence: 99%

Low energy analyzing powers in pion–proton elastic scattering

et al. 2004

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“…To conclude, a remarkable value of 38 MeV was found for the nonperturbative contribution to the pion-nucleon σ term, viz. via a scalar lightquark tadpole [25] or condensate [26]. Recently, a surprising value of 38 MeV was also obtained in a lattice computation [27] of the whole πN σ term.…”

Section: Evidence Of a Very Light Spinless Boson At 38 Mevmentioning

confidence: 93%

$Z_0(57)$ and $E(38)$: possible surprises in the Standard Model

van Beveren,

Rupp

2020

Preprint

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With the reported observation of the Higgs boson at the LHC, the Standard Model of particle physics seems to be complete now as for its particle content. However, several experimental data at low and intermediate energies indicate that there may be two surprises. First we propose a tentative new boson Z 0 (57), with a mass of about 57 GeV, on the basis of small enhancements we observe in several experiments, using recent data obtained at the LHC as well as much older ones from LEP. If confirmed, we interpret this new particle as a pseudoscalar or scalar partner of a composite Z vector boson. Secondly, we advocate the existence of a very light spinless boson E(38), probably a scalar, with a mass of 38 MeV and decaying into two photons. Theoretical arguments and experimental signals supporting such a novel light boson will be presented, including a recent direct experimental confirmation at the Joint Institute for Nuclear Research in Dubna.

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“…The spherically symmetric hedgehog Ansatz for the B = 1 soliton solution of the standard Skyrme model can be generalized to The boundary conditions that the profile functions satisfy at infinity are 48) and at the center (r = 0) are…”

Section: Dynamics Of the Single Skyrmionmentioning

confidence: 99%

Skyrmion Approach to Finite Density and Temperature

Park

Riska

2016

The Multifaceted Skyrmion

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We review an approach, developed over the past few years, to describe hadronic matter at finite density and temperature, whose underlying theoretical framework is the Skyrme model, an effective low energy theory rooted in large Nc QCD. In this approach matter is described by various crystal structures of skyrmions, classical topological solitons carrying baryon number, from which conventional baryons appear by quantization. Chiral and scale symmetries play a crucial role in the dynamics as described by pion, dilaton and vector meson degrees of freedom. When compressed or heated skyrmion matter describes a rich phase diagram which has strong connections with the confinement/deconfinement phase transition. IntroductionAn important issue at present is to understand the properties of hadronic matter under extreme conditions, e.g., at high temperature as in relativistic heavy-ion physics and/or at high density as in compact stars. The phase diagram of hadronic matter turns out richer than what has been predicted by perturbative Quantum Chromodynamics (QCD).1 Two approaches have been developed thus far to discuss this issue : on the one hand, Lattice QCD which deals directly with quark and gluon degrees of freedom, and on the other, effective field theories which are described in terms of hadronic fields. We shall describe in here a formalism for the second approach based on the topological soliton description of hadronic matter firstly introduced by Skyrme. 2,3Lattice QCD, the main computational tool accessible to highly nonperturbative QCD, has provided much information on the the finite temperature transition, such as the value of the critical temperature, the type of equation of state, etc.

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The CONTRIBUTION OF THE LIGHT QUARK CONDENSATE TO THE ΠN SIGMA TERM

Cited by 4 publications

References 39 publications

Low energy analyzing powers in pion–proton elastic scattering

Low energy analyzing powers in pion–proton elastic scattering

$Z_0(57)$ and $E(38)$: possible surprises in the Standard Model

Skyrmion Approach to Finite Density and Temperature

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