Data on Elementary Particles and Resonant States

Rosenfeld, Arthur H.; Barbaro‐Galtieri, A.; Barkas, Walter H.; Bastien, Pierre; Kirz, Janos; Roos, M.

doi:10.1103/revmodphys.36.977

Cited by 209 publications

(26 citation statements)

References 11 publications

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“…Such an analytic structure, with two very asymmetric poles in different sheets of an angular momentum zero partial the to is almost m in the analysis of Ref. [20] has not been supported by there is a striking splitting in the curve describing the evolution of the σ mass, which does not occur anywhere for the ρ(770).…”

Section: Mass Ofmentioning

confidence: 94%

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From controversy to precision on the sigma meson: A review on the status of the non-ordinary f0(500) resonance

2016

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The existence and properties of the sigma meson have been controversial for almost six decades, despite playing a central role in the spontaneous chiral symmetry of QCD or in the nucleonnucleon attraction. This controversy has also been fed by the strong indications that it is not an ordinary quark-antiquark meson. Here we review both the recent and old experimental data and the model independent dispersive formalisms which have provided precise determinations of its mass and width, finally settling the controversy and leading to its new name: f 0 (500). We then provide a rather conservative average of the most recent and advanced dispersive determinations of its pole position √ s σ = 449 +22−16 −i(275±12). In addition, after comprehensive introductions, we will review within the modern perspective of effective theories and dispersion theory, its relation to chiral symmetry, unitarization techniques, its quark mass dependence, popular models, as well as the recent strong evidence, obtained from the QCD 1/N c expansion or Regge theory, for its non ordinary nature in terms of quarks and gluons.

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Section: Mass Ofmentioning

confidence: 94%

“…Very soon after it was suggested theoretically, a narrow σ already appeared in the 1964 edition of the RPP-at that time called "Data on Elementary particles and Resonant states" [20]. Several references were listed with a mass around 390 MeV and a width between 50 and 150 MeV.…”

Section: To Be or Not To Be: The σ History In The Review Of Particle mentioning

confidence: 99%

From controversy to precision on the sigma meson: A review on the status of the non-ordinary f0(500) resonance

2016

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“…Figure 2 shows a plot of the inelastic cross section calculated from the S u absorption parameter (b ll ) of different phase-shift analyses, 3 " 7 using ff inel (S ll ) = °-35X 3^( 1 -6 ll 2) -Here 0.35 is the branching ratio R(ri~ 27/77^ all decays), 8 and f is an isotopic-spin projection factor. It is seen that the experimental 77 production and theS n absorption cross section are very similar below the 7?…”

Section: ^2ymentioning

confidence: 99%

Total and Differential Cross Sections forπ−+p→η+nfrom Threshold to 1300 MeV

et al. 1966

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We have measured the total and differential cross sections for the reaction TT~+p-~n-t-n ^2y(1) at seven different pion energies from threshold to 1300 MeV. We find that the total cross section for (1) rises steeply from threshold to a value of nearly 1 mb at an incident-pion kinetic energy (T^-) between 655 and 704 MeV, and then falls gradually to 0.25 mb at 1300 MeV. This agrees with previous work. x Our T? angular distributions are isotropic near threshold, but in contrast to Ref. 1, require terms through cos 2^* for an adequate fit at T 7r -= 655 MeV, with higher order terms gradually appearing with increasing energy. The experimental setup consisted of a cubic array of six steel-plate spark chambers (47r solid angle) surrounding a liquid-hydrogen target at the center of a 1-m 3 cavity. Only events with neutral final particles were allowed to trigger the spark chambers. This apparatus will be described more fully elsewhere. 2 A Monte Carlo study was made of the detection efficiency of the spark chambers for highenergy photons. For the gammas from r? decay this turned out to be close to 100%.Two-shower events were accepted for analysis when (a) each shower produced sparks in three of five consecutive gaps, (b) no sparks appeared in the first four gaps (the first four plates were ^-in. Al), and (c) the event appeared to originate near the target. About 3400 r? events survived these selection criteria. The r? events were separted from the 7r° events (from ir~+p -*7r°+w) by means of the distribution in opening angle of the two gamma rays. Figure 1 shows the opening-angle distribution obtained at ^-= 704 MeV. Opening-angle distributions were calculated by Monte Carlo techniques for various reactions contributing to the background.A linear combination of the expected openingangle distributions was fitted to the experimental distribution by the method of least squares, yielding the relative strength of the various competing reactions. The ratio of rj production to n-N charge exchange was multiplied by the charge-exchange cross section, also measured in this experiment, 2 to yield the "partial" 77-production cross section. This ratio is listed in Table I. The cross section is plotted in Fig. 2, along with the results from Ref. 1. The agreement is excellent. It should be emphasized that these numbers represent the "partial" production cross section for rj-* 2y only.To form the angular distribution at each energy, two-shower events were selected within opening-angle limits from 3 deg below the minimum to a maximum angle which included 75% of the 7] events. We were not able to measure the relative energy of the two showers well enough to resolve the two-fold ambiguity in the r\ direction. Consequently, we used the angular distributions of the bisector between the two observed showers to determine the 77

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“…The coupling constants satisfy the sum rule (23).^^ Comparing with Eq. (22) we find that VJgn^-s-T» is about 27% smaller than gFi*Ar-, which is quite rea sonable, since the measurement of the Fi*~ -> S~+7r^ width is within errors of 50%. In conclusion the sum rules for the resonance width are reasonably well satisfied.…”

Section: Comparison With Experimental Datamentioning

confidence: 50%

Coupling Constants in BrokenŨ(12)Symmetry

Flamm

1966

Phys. Rev.

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Data on Elementary Particles and Resonant States

Cited by 209 publications

References 11 publications

From controversy to precision on the sigma meson: A review on the status of the non-ordinary f0(500) resonance

From controversy to precision on the sigma meson: A review on the status of the non-ordinary f0(500) resonance

Total and Differential Cross Sections forπ−+p→η+nfrom Threshold to 1300 MeV

Coupling Constants in BrokenŨ(12)Symmetry

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