共查询到20条相似文献,搜索用时 31 毫秒
1.
A. Sibirtsev J. Haidenbauer H. -W. Hammer U. -G. Meißner 《The European Physical Journal A - Hadrons and Nuclei》2007,32(2):229-241
We utilize existing inclusive data on K+-meson momentum spectra of the reaction pp→K
+
X at T
p = 2.3-2.85GeV to deduce total cross-sections for pp→K
+
Σ
+
n. The method used to extract those cross-sections is explained and discussed in detail. Our result for T
p = 2.85GeV is consistent with the data point from a direct measurement at the same beam energy. The cross-section obtained
for T
p = 2.3GeV is with 13.7±2.3μb considerably smaller than the value found in a recent experiment by the COSY-11 Collaboration
at a somewhat lower beam energy, indicating that the pp→K
+
Σ
+
n reaction cross-section could exhibit a rather unusual energy dependence. 相似文献
2.
O. Bartholomy R. Bogendörfer V. Credé I. Fabry A. V. Anisovich G. Anton R. Bantes Y. A. Beloglazov R. Castelijns A. Ehmanns J. Ernst H. Flemming A. Fösel M. Fuchs Ch. Funke R. Gothe A. B. Gridnev E. Gutz S. Höffgen I. Horn J. Hößl J. Junkersfeld H. Kalinowsky F. Klein E. Klempt H. Koch M. Konrad B. Kopf B. Krusche J. Langheinrich H. Löhner I. V. Lopatin J. Lotz H. Matthäy D. Menze J. Messchendorp V. A. Nikonov D. V. Novinski M. Ostrick H. van Pee A. K. Radkov A. V. Sarantsev S. Schadmand C. Schmidt H. Schmieden B. Schoch G. Suft V. V. Sumachev T. Szczepanek U. Thoma D. Walther Ch. Weinheimer 《The European Physical Journal A - Hadrons and Nuclei》2007,33(2):133-146
Photoproduction of η -mesons was studied with the Crystal-Barrel detector at ELSA for photon energies in the range from 0.75
to 3GeV. Total and differential cross-sections are presented. The η mesons are detected in two decay modes, in η → 2γ and
in η → 3π0 → 6γ . The cross-sections vary slowly as functions of energy and η production angle suggesting that only few resonances make
significant contributions to the cross-section. For photon energies above 1.5GeV, the differential cross-sections show a strong
forward peak due to meson exchanges in the t channel. A comparison of the η -photoproduction cross-sections with SAID and MAID as well as with a partial-wave analysis
performed on our data in combination with other data sets shows good agreement. The Bonn-Gatchina partial-wave analysis suggests
that the largest contribution to η photoproduction for energies below 3GeV proceeds via three resonances, the well-known N(1535)S
11 , via N(1720)P
13 , and a newly suggested N(2070)D
15 . 相似文献
3.
We present a pion photoproduction model on the free nucleon based on an Effective Lagrangian Approach (ELA) which includes the nucleon resonances (Δ(1232), N(1440), N(1520), N(1535), Δ(1620), N(1650), and Δ(1700)), in addition to Born and vector meson exchange terms. The model incorporates a new theoretical treatment of spin-3/2 resonances, first introduced by Pascalutsa, avoiding pathologies present in previous models. Other main features of the model are chiral symmetry, gauge invariance, and crossing symmetry. We use the model combined with modern optimization techniques to assess the parameters of the nucleon resonances on the basis of world data on electromagnetic multipoles. We present results for electromagnetic multipoles, differential cross-sections, asymmetries, and total cross-sections for all one pion photoproduction processes on free nucleons. We find overall agreement with data from threshold up to 1 GeV in laboratory frame. 相似文献
4.
The K-matrix approach with effective Lagrangians is used to describe the S and P pion-nucleon partial-wave amplitudes in the energy range E
lab≤ 1 GeV. It is demonstrated, that treating the resonance as K-matrix a pole gives the natural way to separate the resonance and non-resonance parts of the πN amplitude. The model includes all the four-star πN resonances, the non-resonance contributions are calculated from relevant Feynman graphs without any phenomenological form
factors. Different contributions to the inelastic π−
p→ηn amplitude are estimated.
Received: 9 July 1998 相似文献
5.
H. van Pee O. Bartholomy V. Crede A. V. Anisovich G. Anton R. Bantes Yu. Beloglazov R. Bogendörfer R. Castelijns A. Ehmanns J. Ernst I. Fabry H. Flemming A. Fösel M. Fuchs Ch. Funke R. Gothe A. Gridnev E. Gutz St. Höffgen I. Horn J. Hößl J. Junkersfeld H. Kalinowsky F. Klein E. Klempt H. Koch M. Konrad B. Kopf B. Krusche J. Langheinrich H. Löhner I. Lopatin J. Lotz H. Matthäy D. Menze J. Messchendorp V. A. Nikonov D. Novinski M. Ostrick A. Radkov A. V. Sarantsev S. Schadmand C. Schmidt H. Schmieden B. Schoch G. Suft V. Sumachev T. Szczepanek U. Thoma D. Walther Ch. Weinheimer 《The European Physical Journal A - Hadrons and Nuclei》2007,31(1):61-77
Photoproduction of π0-mesons was studied with the Crystal-Barrel detector at ELSA for incident energies from 300MeV to 3GeV. Differential cross-sections
dσ/dΩ, dσ/dt, and the total cross-section are presented. For E
γ < 3GeV, the angular distributions agree well with the SAID parametrization. At photon energies above 1.5GeV, a strong forward
peaking indicates t-channel exchange to be the dominant process. The rapid variations of the cross-section with energy and angle indicate production
of resonances. An interpretation of the data within the Bonn-Gatchina partial-wave analysis is briefly discussed. 相似文献
6.
J. Junkersfeld A. V. Anisovich G. Anton R. Bantes O. Bartholomy R. Beck Yu. Beloglazov R. Bogendörfer R. Castelijns V. Crede A. Ehmanns J. Ernst I. Fabry H. Flemming A. Fösel M. Fuchs Ch. Funke R. Gothe A. Gridnev E. Gutz St. Höffgen I. Horn J. Hößl H. Kalinowsky F. Klein E. Klempt H. Koch M. Konrad B. Kopf B. Krusche J. Langheinrich H. Löhner I. Lopatin J. Lotz H. Matthäy D. Menze J. Messchendorp V. A. Nikonov D. Novinski M. Ostrick H. van Pee A. Radkov A. V. Sarantsev S. Schadmand C. Schmidt H. Schmieden B. Schoch G. Suft V. Sumachev T. Szczepanek U. Thoma D. Walther Ch. Weinheimer 《The European Physical Journal A - Hadrons and Nuclei》2007,31(3):365-372
Differential and total cross-sections for photoproduction of γp→pπ
0
ω and γp→Δ
+
ω were determined from measurements of the CB-ELSA experiment, performed at the electron accelerator ELSA in Bonn. The measurements
covered the photon energy range from the production threshold up to 3GeV. 相似文献
7.
P. González J. Vijande A. Valcarce H. Garcilazo 《The European Physical Journal A - Hadrons and Nuclei》2007,31(4):515-518
We show that nonstrange baryon resonances can be classified according to multiplets of SU(4)⊗O(3). We identify spectral regularities and degeneracies that allow us to predict the high-spin spectrum from 2 to 3GeV. 相似文献
8.
V. Pascalutsa 《The European Physical Journal A - Hadrons and Nuclei》2003,16(2):149-153
The nearest-neighbor mass-spacing distribution of the meson and baryon spectrum (up to 2.5 GeV) is described by the Wigner surmise corresponding to the statistics of the Gaussian orthogonal ensemble of random matrix theory. This can be viewed as a manifestation of quantum chaos in hadrons.
Received: 30 September 2002 / Accepted: 21 November 2002 / Published online: 4 February 2003
RID="a"
ID="a"Present address: Department of Physics and Astronomy, Ohio University, Athens, OH 45701, USA; e-mail: vlad@phy.ohiou.edu
Communicated by G. Orlandini 相似文献
9.
Cross-sections, beam asymmetries, and recoil polarisations for the reactions γp → K
+Λ;γp → K
+Σ0, and γp → K
0Σ+ have been measured by the SAPHIR, CLAS, and LEPS Collaborations with high statistics and good angular coverage for centre-of-mass
energies between 1.6 and 2.3 GeV. The combined analysis of these data with data from π and η photoproduction reveals evidence
for new baryon resonances in this energy region. A new P11 state with mass 1840 MeV and width 140 MeV was observed contributing to most of the fitted reactions. The data demand the
presence of two D13 states at 1875 and, optimistically, at 2170 MeV. 相似文献
10.
O. V. Selyugin 《The European Physical Journal A - Hadrons and Nuclei》2006,28(1):83-89
The analysing power AN is examined in the range of the Coulomb-hadron interference on the basis of the experimental data from pL = 6 GeV/c up to 200 GeV/c taking account of a phenomenological analysis at pL = 6 GeV/c and a dynamic high-energy spin model. The results are compared with the new RHIC data at pL = 100 GeV/c. The new experimental data obtained at RHIC indicate small contributions of the hadron spin-flip amplitude. 相似文献
11.
B. Pasquini D. Drechsel L. Tiator 《The European Physical Journal A - Hadrons and Nuclei》2006,27(2):231-242
The relativistic amplitudes of pion photoproduction are evaluated by dispersion relations at t = const. The imaginary parts of the amplitudes are taken from the MAID model covering the absorption spectrum up to center-of-mass
energies W = 2.2GeV. For sub-threshold kinematics the amplitudes are expanded in powers of the two independent variables ν and t related to energy and momentum transfer. Subtracting the loop corrections from this power series allows one to determine
the counter terms of covariant baryon chiral perturbation theory. The proposed continuation of the amplitudes into the unphysical
region provides a unique framework to derive the low-energy constants to any given order as well as an estimate of the higher-order
terms by global properties of the absorption spectrum. 相似文献
12.
Zhi-Gang Wang 《The European Physical Journal C - Particles and Fields》2009,61(2):321-329
We calculate the masses and the pole residues of the
heavy baryons Ω
c
0(css) and Ω
b
−(bss) with the QCD sum rules. The numerical values
GeV (or
GeV) and
GeV (or
GeV) are in good agreement with the experimental data. 相似文献
13.
S. Schneider S. Krewald Ulf-G. Meißner 《The European Physical Journal A - Hadrons and Nuclei》2006,28(1):107-113
A resonance model for two-pion production in the pion-nucleon reaction is developed that includes information obtained in
the analysis of pion-nucleon scattering in a meson-exchange model. The baryonic resonances Δ(1232), N*(1440), N*(1520), N*(1535), and N*(1650) are included. The model reproduces the total cross-sections up to kinetic energies of the incident pion of 400MeV and
obtains the shapes of the differential cross-sections in reasonable agreement with the data. 相似文献
14.
S. R. Cotanch I. J. General P. Wang 《The European Physical Journal A - Hadrons and Nuclei》2007,31(4):656-661
The Coulomb gauge Hamiltonian model is used to calculate masses for selected JPC states consisting of exotic combinations of quarks and gluons: ggg glueballs (oddballs), qˉg hybrid mesons and qˉqˉ tetraquark systems. An odderon Regge trajectory is computed for the J- glueballs with intercept much smaller than the pomeron, explaining its nonobservation. The lowest 1-+ hybrid-meson mass is found to be just above 2.2GeV while the lightest tetraquark state mass with these exotic quantum numbers
is predicted around 1.4GeV consistent with the observed π(1400). 相似文献
15.
An extensive and systematic study of the recent η photo-production data up to 1.2 GeV is presented within a chiral constituent
quark model. A model embodying all known nucleonic resonances shows clear need for a yet undiscovered third S11 resonance in the second resonance region, for which we determine the mass (1.729 GeV) and the total width (183 MeV). Furthermore,
we extract the configuration mixing angles, an important property of the quark-quark interaction in the quark model, for the
resonances S
11(1535) and S
11(1650), as well as for the resonances D
13(1520) and D
13(1700). Our results agree well with the quark model predictions. In addition, the partial ηN decay widths and/or the photo-excitation helicity amplitudes for the nucleonic resonances S
11(1535), S
11(1650), P
11(1710), P
13(1720), D
13(1520), D
13(1700), D
15(1675), and F
15(1680) are also obtained in this approach.
Received: 14 February 2001 / Accepted: 22 June 2001 相似文献
16.
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
17.
《The European Physical Journal A - Hadrons and Nuclei》2008,38(2):195-207
The photoproduction of η -mesons off 12C , 40Ca , 93Nb , and
nat
Pb nuclei has been measured with a tagged photon beam with energies between 0.6 and 2.2GeV. The experiment was performed at
the Bonn ELSA accelerator with the combined setup of the Crystal Barrel and TAPS calorimeters. It aimed at the in-medium properties
of the S
11(1535) nucleon resonance and the study of the absorption properties of nuclear matter for η -mesons. Careful consideration
was given to contributions from ηπ final states and secondary production mechanisms of η -mesons, e.g. from inelastic πN reactions of intermediate pions. The analysis of the mass number scaling shows that the nuclear absorption cross-section
for η -mesons is constant over a wide range of the η momentum. The comparison of the excitation functions to data off the
deuteron and to calculations in the framework of a BUU model show no unexplained in-medium modifications of the S
11(1535) . 相似文献
18.
19.
We present the analysis of the decay widths of excited baryons in the framework of the 1/N
c expansion of QCD. These studies are performed up to order 1/N
c and include both positive- and negative-parity excited baryons. 相似文献
20.
A combined analysis of photoproduction data on γp↦ πN, ηN was performed including the data on KΛ and KΣ. The data are interpreted in an isobar model with s-channel baryon resonances and π, ρ (ω), K, and K
* exchange in the t-channel. Three baryon resonances have a substantial coupling to ηN, the well-known N(1535)S
11, N(1720)P
13, and N(2070)D
15. The inclusion of data with open strangeness reveals evidence for further new resonances, N(1840)P
11, N(1875)D
13 and, with weaker evidence, for N(2170)D
13. 相似文献