High resolution proton inelastic scattering from 50Cr

Resonances in the ⁵⁰Cr(p, p′γ) reaction were investigated with the TUNL high resolution system. All previously observed p-wave resonances between Ep = 2.00 and 3.03 MeV were studied. Measurement of the p' and the γ-ray angular distributions provides sufficient information to determine unambiguously the J-value of the resonance and the magnitude and relative phase of the inelastic decay amplitudes. Expressions are given for the appropriate angular distributions and for the transformation between the channel spin and the total angular momentum representation. Experimental results are presented for 24 p-wave resonances in ⁵¹Mn including decay amplitudes and relative phases for $\text{16}\text{3}\text{2}{}^{\mathrm{?}}$ resonances. Six resonances formerly assigned $\text{1}\text{2}{}^{\mathrm{?}}$ are reassigned $\text{3}\text{2}{}^{\mathrm{?}}$. Inelastic spectroscopic factors were determined for two analogue states. Proton strength functions were evaluated from both the elastic and inelastic data.     

Observation of intermediate structure in inelastic proton amplitudes in 49V

The magnitudes and relative signs of inelastic proton channel amplitudes were measured for $\text{72}\text{3}\text{2}{}^{\mathrm{?}}$ resonances in ⁴⁹V. Localized non-statistical behavior is observed in the inelastic amplitudes.     

A study of the reactions KN→Σ(1385)π between 0.6 and 1.2 GeV/c

An energy-dependent partial-wave analysis of the reaction $\text{K}\text{N}\text{→Σ(1385)π}$ has been performed in the energy region lying between 1.65 and 1.85 GeV. The resonant amplitudes of seven well known Y¹ resonances have been determined, and used to compute the corresponding (8) ? (10) SU (3) coupling constants.     

Baryons in dual unitarization and dynamical thresholds

Baryon exchange and baryon resonance production is introduced in the dual unitarisation scheme. The dynamical threshold for the production of meson and baryon resonances is incorporated. It is shown that the intercepts of the ω and the f, which are generated by baryons, are suppressed by the above dynamical threshold effects to $\text{α}{}_{\mathrm{\omega }}\text{(0) ? 0}$ and α_f(0) < 0. The pomeron is shifted slightly upwards by baryon production. An upper limit is determined for the ratio of the crossed and uncrossed produced baryon lines. The breaking of the Freund-Rosner-Walz rule is discussed.     

Dibaryon signals in the excitation functions of polarized πd scattering

Quantitative estimates of the role of the dibaryon resonances ¹D₂, ³F₃ and ¹G₄ in the πd channel are made. Exc functions for vector and tensor polarisations for πd → π$\text{d}$ are calculated for T^π < 650 MeV by admixing dibaryon resonances of conservative strength to the impulse approximation background. The reliability of the background amplitudes for θ ? 70° is checked by comparing with results from a Faddeev calculation.     

Neutrino-excitation of baryon resonances and single pion production

This is an attempt to describe all existing data on neutrino production of single pions in the resonance region up to W = 2 GeV in terms of the relativistic quark model of Feynman, Kislinger and Ravndal (FKR). We considered single pion production to be mediated by all interfering resonances below 2 GeV. A simple noninterfering, nonresonant background of isospin $\text{1}\text{2}$ was added. It improved agreement with experiment, particularly in the ratio of isospin amplitudes in charged current reactions, at the expense of one additional constant. All total cross sections, cross section ratios and W-distributions are well reproduced at low and high energies, with charged and neutral currents (supposing the Salam-Weinberg theory with sin²$\text{θ}{}_{\mathrm{w}}\text{≈}\text{1}\text{4}$ to be correct), and for neutrinos and antineutrinos, giving predictions where data are lacking. New predictions have been made for complex angular distributions in $\text{N}$π channels exhibiting strong interference between neighbouring resonances. These are sensitive (for 1.1 GeV ? W ? 1.5 GeV) to the sign of the Roper resonance P₁₁(1450) which is controversial in photoproduction experiments.     

Final-state interactions with inelastic effects in non-leptonic hyperon decays

A recent work by Reid and Trofimenkoff seemed to indicate that a satisfactory model using current algebra, PCAC and the soft-pion limit can be formulated to obtain the s- and p-wave amplitudes of the non-leptonic decays of Λ and Σ, as well as the $\text{ΔI =}\text{1}\text{2}$rule if final state interactions are included. We demonstrate in this paper that by including inelastic effects in the final-state interactions (that is without the usual approximation of elastic unitarity) the results bring us back full circle. The disagreement between theory and experiment for the p-wave amplitudes still persists and no significant suppression of the $\text{I =}\text{3}\text{2}$ state for the final particles can be predicted.     

Calculation of baryon masses in quantum chromodynamics

The polarization operator of quark currents with baryon quantum numbers is considered in quantum chromodynamics. The non-zero mean vacuum values of the field operator products are taken into account. The sum rules are obtained assuming that in the virtuality region ～1 GeV, among the mean vacuum values violating the chiral invariance, the most important is $\text{〈0|}\text{ψ}\text{ψ|0〉}$. Saturating these sum rules by the lowest baryonic states one is able to calculate the masses of the isobar Δ and nucleon N, M_Δ = 1.4 GeV, M_N = 1 GeV, up to 15% through the known value $\text{〈0|}\text{ψ}\text{ψ|0〉}$. The mass splitting in the baryonic decuplet $\text{M}{}_{\mathrm{\Sigma 1}}\text{?M}{}_{\mathrm{\Delta }}\text{= 125}\text{MeV}$ is calculated in first order in the current strange quark mass m_s = 150 MeV. Certain results for other baryonic resonances have also been obtained.     

Precise hadron mass calculations from lattice QCD

By using scalar as opposed to spin-$\text{1}\text{2}$ quarks and treating spin effects perturbatively, the masses of the lowest lying 0^- and 1^- mesons above 1 GeV (the J/Ψ, η_c, D, D¹, F, F¹, and φ) are calculated to 1%. The masses of the K¹, ?, and K are respectively obtained to 3%, 8% and 30%. Certain (spin-averaged) linear combinations of baryon masses are also computed. The nucleon-delta result differs from experiment by 8%. For heavier baryons the error is smaller. Scalar lattice QCD seems to be a promising approach to the strong interactions.     

The NN cross sections and resonances

The N$\text{N}$ amplitudes for J ? 2 are calculated using Bryan-Phillips non static OBEP and treating annihilation in the framework of a many channel N/D-formalism. For the first time all poles are found simultaneously with cross sections, reasonably well reproduced by adjusting only the coupling of the annihilation channel. The resonances have large widths and partial wave cross sections do not show any structure, suggesting that the recently found N$\text{N}$ resonances, both narrow and wide, are not of quasi nuclear origin.     

Off-shell NN annihilation studied in π+p interactions at 8 and 16 GeV/c

Interactions in which the baryon is emitted forwards in the c.m.s. are studied in 8 and 16 GeV/cπ⁺p collisions. These interactions are interpreted as representing baryon exchange. The properties of such off-shell $\text{N}$N annihilation events are studied. It is found that the multiplicity distribution of the multi-pion system as a function of the effective mass for events with |u_pp| < 1 GeV² is the same as for real $\text{N}\text{N}$ annihilations.     

SL(4,R) classification for hadrons

It is suggested that the complete spectrum of baryon and meson resonances for each flavour is given by spinor and tensor infinite-component systems based on unitary irreducible representations of $\text{SL}$(4,R). This is a shell-model-like dynamical geometrical symmetry, presumably resulting from the quark structure and QCD, with possible connections to gravity. The fit to observations is excellent.     

A comment on the phenomenology of the SU(3) Skymre model

We find that the realistic baryon mass spectrum in the SU(3) Skyrme model with massive 0^? mesons can be obtained only for F_π < 70 MeV. We fit m_Λ and and obtain baryon masses within the limits of ± 16% of the experimental val ues, but at the expense of very low ifF_π=46.32 MeV.     

20Ne + n → 21Ne(T = 32) resonances

$\text{T =}\text{3}\text{2}$ resonances in ²¹Ne have been studied in measurements of the total neutron cross section of ²⁰Ne using the 190 m neutron time-of-flight facility of the Karlsruhe Isochronous Cyclotron. The high time-of-flight resolution of 6.6 ps/m enabled the study of sharp $\text{T =}\text{3}\text{2}$ resonances in ²¹Ne with an effective energy resolution of up to 4000. Five $\text{T =}\text{case3}\text{2}$ levels have been observed as sharp resonances allowing the precise determination of total width Λ, partial decay with Λ_no and resonance energy E_R. The c.m. resonance parameters of the first $\text{T =}\text{3}\text{2}$ state in ²¹Ne are E_R = 2098.6 ± 0.3 keV, Λ = 2.2 ± 0.5 keV and Λ_no = 0.21 ± 0.05 keV. Upper limits for the partial decay widths are deduced for those $\text{T =}\text{3}\text{2}$ levels which do not appear as resonance anomalies. A search for additional $\text{T =}\text{3}\text{2}$ states was undertaken. The resonance energies are discussed in the framework of the isbobaric mass multiplet equation. The decay widths are compared with shell-model predictions of isospin mixing and the systematics of isospin-non-conserving particle decays.     

Spectroscopic amplitudes for complex cluster systems

By expanding the Bargmann-Segal integral transform of nomi and overlap kernels in appropriately SU(3) coupled Bargmann space functions, the calculation of norm and overlap matrix elements in a cluster model basis is reduced to purely algebraic techniques involving the algebra of SU(3) recoupling transformations. This technique has been further developed to make calculations possible for systems of two heavy fragments other than closed-shell nuclei. In one application of the method, analytic expressions are given for the norms of binary fragment systems in which a light fragment of mass number ?, ? ? 4, is combined with a heavy fragment of mass number $\text{A-?,}\text{with}\text{A-? ? 24}$. The $\text{A-?}$ fragment nuclei with different p- and sd-shell structure illustrate somewhat different problems in the recoupling technique. In a second application, spectroscopic amplitudes are calculated for the most important open channels of the ¹²C+ ¹²C resonances. Eigenvalues and eigenvectors of the antisymmetrizer are evaluated in a “molecular basis” of the ¹²C + ¹²C system, in which each ¹²C nucleus is assumed to have SU(3) symmetry (04) with internal rotational excitations of 0⁺,2⁺ and 4⁺. Reduced width amplitudes are calculated connecting such normalized, fully antisymmetrized molecular basis states to exit channels which include: α+²⁰Ne with ²⁰Ne internal functions of (80) SU(3) symmetry, (K = 0⁺ band, and (82) SU(3) symmetry, (K = 2^? band); ¹⁶O+⁸Be; and ²³Na+p or ²³Mg+n fragments with ²³Na or ²³Mg excitations in $\text{K =}\text{3}\text{2}\text{and}\text{1}\text{2}$ rotational bands of SU(3) symmetry (83).     

Asymptotic energy scale factors for pseudoscalar meson scattering and charmed meson couplings

Energy scale factors ν₀ for PP → PP scattering amplitudes are related via the absence of exotic resonances to ratios of tensor to vector coupling strengths. These same ratios are extracted from FESR's for non-exotic reactions. The scale factors obtained are all of the order of 1.0 GeV²or less, independent of quantum numbers. This contradicts the expectations of dual amplitudes in which ν₀ = 1/α′, and trajectory slopes are smaller for charmed mesons. Decay widths for tensor mesons are predicted. An observed SU(3) violation for the ratio $\text{A}{}_2\text{→}\text{K}\text{K}\text{/}\text{K}{}^7\text{→}\text{K}\text{π}$ is shown to be consistent with the FESR results. Charmed meson decays are predicted to be factors of 2–3 larger than those predicted by SU(4).     

Baryon poles in proton decay amplitudes

The decay rate of the p→π⁰e⁺ mode is calculated in SU(5) grand unified theory using a pole model with proton and $\text{1}\text{2}{}^{\mathrm{?}}$ baryon poles. Baryon-to-vacuum amplitudes are calculated in the framework of the MIT bag model. It is found that the partial decay rate [～(5×10³¹ yr)^?)] is close to the partial decay rates calculated by different methods.