共查询到20条相似文献,搜索用时 38 毫秒
1.
2.
We study the interaction of vector mesons with the octet of stable baryons in the framework of the local hidden gauge formalism
using a coupled-channels unitary approach, including also the pseudoscalar-baryon channels which couple to the same quantum
numbers. We examine the scattering amplitudes and their poles, which can be associated to the known J
P = 1/2−, 3/2− baryon resonances, and determine the role of the pseudoscalar-baryon channels, changing the width and eventually the mass
of the resonances generated with only the basis of vector-baryon states. 相似文献
3.
N. Sharma A. Martinez Torres K. P. Khemchandani H. Dahiya 《Physics of Particles and Nuclei》2014,45(1):32-34
We calculate the magnetic moments of the low lying negative-parity J P = 1/2?, 3/2? Λ resonances within the framework of chiral constituent quark model. The explicit contribution coming from the valence and sea quarks are being calculated. 相似文献
4.
D. Faiman 《Nuclear Physics B》1972,50(1):379-406
We present a least squares fit to the experimental data on decays of negative parity baryon resonances into a pseudoscalar meson and either a JP = 1/2+ stable baryon or a JP = 3/2+ decuplet member. We find that the s-waves and d-waves are separately in good agreement with the predictions of SU (6)w ⊗ O(2)Lz. Predictions are given regarding several as yet unobserved decay processes, and for those which concern hitherto undetected resonances, their possible detection is discussed. 相似文献
5.
B. Borasoy 《The European Physical Journal A - Hadrons and Nuclei》2000,9(1):95-107
The importance of Born terms and resonance exchange for η and η' photoproduction off both the proton and neutron within
U(3) baryon chiral perturbation theory is investigated. Low-lying resonances such as the vector mesons and J
P = 1/2+, 1/2- baryon resonances are included explicitly and their contributions together with the Born terms are calculated. The coupling
constants of the resonances are determined from strong and radiative decays. We obtain reasonable agreement with experimental
data near threshold.
Received: 17 March 2000 / Accepted: 8 September 2000 相似文献
6.
The coupled-channels formalism, which has been previously applied successfully to interpret the negative-parity resonances in4He, has now been extended to the positiveparity 2?ω resonances in this system. The 1p-1h approach has been modified to include coupling to the 2p-2h configurations, which also belong to 2?ω excitations, by using the effective operator formalism. The effect of the Pauli term in thes-wave channel is examined and is found to be important in reproducing the 0+,T=0 resonance energy and width. Resonances with spins up toJ π=3+ have been studied, and the agreement with available data is satisfactory. In particular, from the good fit to the asymmetry coefficientβ(E), one establishes the presence of a 2+,T=0 resonance around 35-MeV excitation in the system. 相似文献
7.
We have performed a calculation for the three-body ????? system by using the fixed center approximation to Faddeev equations, taking the interaction between ?? and ??, ?? and ??, and ?? and ?? from the chiral unitary approach. We find several peaks in the modulus squared of the three-body scattering amplitude, indicating the existence of resonances, which can be associated to known I?=?1/2, 3/2 and J P ?=?1/2+, 3/2+ and 5/2+ baryon states. 相似文献
8.
C. Garcıa-Recio J. Nieves L. L. Salcedo 《The European Physical Journal A - Hadrons and Nuclei》2007,31(4):540-542
Starting from a consistent SU(6) extension of the Weinberg-Tomozawa (WT) meson-baryon chiral Lagrangian ( Phys. Rev. D 74, 034025 (2006)), we study the s-wave meson-baryon resonances in the strangeness S = - 3 and negative-parity sectors. Those resonances are generated by solving the Bethe-Salpeter equation with the WT interaction
used as kernel. The considered mesons are those of the 35-SU(6)-plet, which includes the pseudoscalar (PS) octet of pions and the vector (V) nonet of the rho-meson. For baryons we consider
the 56-SU(6)-plet, made of the 1/2+ octet of the nucleon and the 3/2+ decuplet of the Delta. Quantum numbers I(J
P) = 0(3/2-) are suggested for the experimental resonances Ω
*(2250)- and Ω
*(2380)-. Among other, resonances with I = 1 are found, which minimal quark content is sssˉl', being s the strange quark and l, l' any of the the light up or down quarks. A clear signal for such a pentaquark would be a baryonic resonance with strangeness -3 and electric charge -2 or
0, in proton charge units. We suggest looking for K
-
Ξ
- resonances with masses around 2100 and 2240MeV in the sector 1(1/2-), and for π
±
Ω
- and K
-
Ξ
*- resonances with masses around 2260MeV in the sector 1(3/2-). 相似文献
9.
We study the peripheral cross sections of resonances that cannot be produced by π-exchange. In particular, we concentrate on the four meson nonets expected as L = 1 quark states (i.e., the JP = 0+πN(980); JP = 1+ A1, B; JP = 2+ A2). We use SU(3), Regge poles, factorization, exchange degeneracy, pole extrapolation, and the vector-meson-photon analogy. We predict the cross sections in both photoproduction and non-diffractive hadronic reactions. In passing, we discuss the large unnatural-parity (B, K?QB) exchange contributions and even the possibility of studying ππ → πω while avoiding the B production background. 相似文献
10.
We investigate mixing of the lowest-lying qqq configurations with J~P=1/2~-caused by the hyperfine interactions between quarks mediated by Goldstone Boson Exchange,One Gluon Exchange,and both Goldstone Boson and One Gluon exchange,respectively.The first orbitally excited nucleon,Σ,ΛandΞstates are considered.Contributions of both the contact term and tensor term are taken into account.Our numerical results show that mixing of the studied configurations in the two employed hyperfine interaction models are very different.Therefore,the present results,which should affect the strong and electromagnetic decays of baryon resonances,may be used to examine the present employed hyperfine interaction models. 相似文献
11.
A. N. Grum-Grzhimaĭlo E. V. Gryzlova A. I. Magunov S. I. Strakhova 《Optics and Spectroscopy》2006,100(4):517-524
The effect of a laser field on the cross section of photoionization of an atom by probe radiation in the region of closely lying autoionizing resonances is studied theoretically. The cross sections in the region of the overlapping autoionizing Rydberg states 5p 5(2 P 1/2)6d′ J = 1 and 5p 5(2 P 1/2)8s′ J = 1 resonantly coupled with the discrete state 5p 5(2 P 3/2)7p[1/2]1 in the xenon atom are calculated. The behavior of the shape and position of resonances in relation to the frequency and intensity of laser radiation is studied. 相似文献
12.
K. P. Khemchandani A. Martínez Torres E. Oset 《The European Physical Journal A - Hadrons and Nuclei》2008,37(2):233-243
We study the ππN system by solving the Faddeev equations, for which the input two-body t-matrices are obtained by solving the Bethe-Salpeter equation in the coupled-channel formalism. The potentials for the ππ, πN sub-systems and their coupled channels are obtained from chiral Lagrangians, which have been earlier used to study resonances in these systems successfully. In this work, we find a resonance in the ππN system with a mass of 1704 ? i375/2MeV and with quantum numbers I = 1/2, J π = 1/2+. We identify this state with the N *(1710). This peak is found where the energies of the ππ sub-system fall in the region of the σ-resonance. We do not find evidence for the Roper resonance in our study indicating a more complex structure for this resonance, nor for any state with total isospin I = 3/2 or 5/2. 相似文献
13.
We write down a set of coupled hydrodynamic equations of the Navier-Stokes type which describe the motion of two compressible, viscous nuclear fluids. The solutions of these equations give rise to giant resonances of both isoscalar and isovector type. The viscosity terms in the equations are responsible for the damping of these resonances. Within this framework we obtain expressions for the width of the resonances as a function of the mass number A, and relations between the widths and the excitation energies for various multipolarities (J = 0+, 1?, 2+, 3?, 4+), and isospins (T = 0,1). The A dependence of the calculated widths exhibit the experimental trends of the giant dipole and isoscalar quadrupole widths. Also, as a result of the calculation we obtain estimates of the values of viscosity coefficients in nuclei. 相似文献
14.
The 19F(p, γ)20Ne radiative capture reaction has been investigated for proton energies of 0.2–1.2 MeV. Excitation functions of γ-rays arising from capture reactions have been measured and the properties of known Jπ = J?J+1 resonances were studied. From the branching ratio and angular distribution measurements, the partial widths for gamma ray and proton emission of the 13.88 MeV level in 20Ne were obtained, and Jπ = 2+, T = 1 assignments for this resonance at EP = 1091keV were made. Lower upper limit for the total width Γ = 0.8 keV has been obtained. 相似文献
15.
Masamichi Tsuboi Yoshiaki Hamada Lucien Henry Jean Chazelas Alain Valentin 《Journal of Molecular Spectroscopy》1984,108(2):328-342
The infrared absorption spectrum of NH2NH2 vapor has been observed in the region 899–1077 cm?1, where the antisymmetric wagging band (va = 1 ← 0) appears, by the use of a Fourier transform spectrometer with a practical resolution of 0.003 cm?1. In the region 925.0–925.6 cm?1, the spectrum was also observed with a tunable diode laser, and a component, β, of the pQ2 cluster has been further resolved. Most of the absorption lines assignable to β-pP2(J″), γ-pP2(J″), β-pQ2(J″), γ-rQ0(J″), β-rR0(J″), and γ-rR0(J″), where J″ = 2 ~ 15, have been identified. From these observed transition frequencies, in combination with the ground state energy levels given by microwave spectroscopy, the energy level structure of the K′ = 1 rotational states was determined. From this, the following molecular parameters for the va = 1 state were determined: molecular asymmetry, B′-C″ = 0.00017 cm?1; a parameter q5 describing an umbrella motion Coriolis interaction (q5K) about the a axis, q5 = ?0.0030 cm?1; its J(J + 1) variation, q5j = 0.00014 cm?1; and a parameter describing an umbrella-motion K-type doubling g5J(J + 1), g5 = 0.000021 cm?1. 相似文献
16.
17.
The electric multipole isovector (τ = 1) giant resonances for Δτz = 0, ± 1 are studied using the self-consistent HF-RPA theory.The distributions of strength, energies, the isospin compositions and other properties of the J = 0+, 1?, 2+ resonances in the 48Ca, 90Zr, 120Sn and 208Pb regions are calculated. Sum rules for the charge-exchange Δτz = ±1 excitations are derived. 相似文献
18.
Wojciech A. Pisarski Joanna Pisarska ?ukasz Grobelny Witold Ryba-Romanowski 《Journal of luminescence》2011,131(4):649-652
Ln-doped oxychloride lead borate glasses were studied using luminescence spectroscopy. Rare earth ions were limited to trivalent Pr3+, Tm3+, Eu3+ and Er3+. Luminescence spectra were registered, which correspond to 3P0-3H4 and 1D2-3H4 transitions of Pr3+, 1G4-3H5 and 1G4-3F4 transitions of Tm3+, 5D0-7FJ (J=0, 1, 2, 3, 4) transitions of Eu3+ and 4S3/2,2H11/2-4I15/2 and 4I13/2-4I15/2 transitions of Er3+. Luminescence decays from the excited states of Ln3+ ions were analyzed in detail. The experimental results indicate that relatively high phonon energy of the host gives important contribution to the excited state relaxation of rare earth ions. 相似文献
19.
W. A. Watson Jr. E. G. Bilpuch G. E. Mitchell 《Zeitschrift für Physik A Hadrons and Nuclei》1980,294(2):153-158
The measurement of inelastic proton channel amplitudes has been extended tof-wave resonances. Ten resonances were studied in the54Fe(p, p′γ) reaction, All were established to haveJ π = 5/2?, and inelastic decay amplitudes were determined for these resonances. Elastic and inelastic spectroscopic factors were determined for the 5/2? analogue state atE p =3.80 MeV. 相似文献
20.
G. Puddu 《The European Physical Journal A - Hadrons and Nuclei》2000,9(2):171-181
We extend the recently presented formalism for Monte Carlo calculations of the partition function, for both even and odd particle
number systems (Phys. Rev. C 59, 2500 (1999)), to the calculation of many-body matrix elements of the type <ψ| e
- βℋ|ψ> where |ψ> is a many-body state with a definite angular momentum, parity, neutron and proton numbers. For large β such
matrix elements are dominated by the lowest eigenstate of the many-body Hamiltonian ℋ, corresponding with a given angular
momentum parity and particle number. Emphasis is placed on odd-mass nuclei. Negligible sign fluctuations in the Monte Carlo
calculation are found provided the neutron and proton chemical potentials are properly adjusted. The formalism is applied
to the J
π = 0+ state in 166
Er and to the J
π = 9/2-, 13/2+, 5/2- states in 165
Er using the pairing-plus-quadrupole model.
Received: 28 April 2000 / Accepted: 20 September 2000 相似文献