Determination of the K(1800) spin parity

A spherical harmonic moment analysis of the reactions K⁻p → K⁻π⁺n and K⁺p → K⁺π⁻Δ⁺⁺ at 13 GeV/c demonstrates the existence of a broad K^* state with mass in the vicinity of 1800 MeV and spin parity 3⁻.     

Unconventional Medium Effect in K+-and π+-Nucleus Scattering

The ratios of total cross section of K⁺-nucleus to K⁺-deuterium at 400 MeV/c≤pk≤800 MeV/c for ⁶Li, ¹²C, ²⁸Si, ⁴⁰Ca and the differential cross section of π⁺-¹²C scattering at p_π= 800 MeV/c are calculated by taking into account the unconventional medium effect.An enhancement of both the K⁺-and π⁺-nucleus scattering cross sections is obtained.     

Single and double dissociation in πp collisions at 11 and 16 GeV/c

The reactions π⁻p → 2π⁻π⁺p, π⁻p → 2π⁻π⁺π^op and π⁻p → 2π⁻2π⁺n are analysed at 11 and 16 GeV/c using longitudinal phase space (LPS) plots. The weighted LPS distributions for π⁻p → 2π⁻π⁺p is dominated by two well separated structures corresponding to single diffraction dissociation of the pion, π⁻p → (2π⁻π⁺)p, and of the proton, π⁻p → π⁻(π⁻π⁺p). The former is more abundant than the latter, and both are approximately constant with energy. In contrast, processes of type π⁻p → (2π)(πp) decrease with increasing energy.

In the five-body reactions the weighted LPS distribution reveals especially at 16 GeV/c a maximum for single dissociation of the proton into 3πp, namely π⁻p → π⁻(π⁻π⁺π^op); this process is likely to be diffractive. The neutron channel has a corresponding maximum displaced toward a multiperipheral configuration π⁻p → π⁻(π⁻2π⁺)n. Another strong maximum corresponds to the pion dissociation π⁻p → (2π⁻π⁺π^o)p. This is interpreted to be an ω-exchange process because no analogous structure occurs in π⁻p → (2π⁻2π⁺)n. Finally, a broad structure reveals double dissociation of both incident particles; it occurs in the two channels π⁻p → (2π⁻π⁺)(π^op) and π⁻p → (2π⁻π⁺)(π⁺n), being stronger in the latter. Further analysis of this process in terms of isospin exchange suggests that it is partially diffractive. Factorization is also discussed.

An appendix gives general aspects of the LPS analysis for the asymptotic study of n-body collisions at very high energy.     

The Role of a1(1260) in π-p→a1-(1260)p and π-p→π-ρ0p Reactions Near Threshold

We report on a theoretical study of the π^-p→a₁^-(1260) p and π^-p→π^-ρ⁰p reactions near threshold within an effective Lagrangian approach. The production process is described by t-channel ρ⁰ meson exchange. For the π^-p→π^-ρ⁰p reaction, the final π^-ρ⁰ results from the decay of the a₁(1260) resonance, which is assumed as a dynamically generated state from the K^*K and ρπ coupled channel interactions. We calculate the total cross section of the π^-p→a₁^-(1260)p reaction. It is shown that, with the coupling constant of the a₁(1260) to ρπ channel obtained from the chiral unitary theory and a cut off parameter Λρ~1.5 GeV in the form factors, the experimental measurement can be reproduced. Furthermore, the total and differential cross sections of π^-p→a₁^-(1260)p→π^-ρ⁰p reaction are evaluated, and it is expected that our model calculations can be tested by future experiments. These reactions are important for the study of the a₁(1260) resonance and would provide further constraints on the properties of the a₁(1260) state.     

Test of the additive quark model in experiments with polarized initial nucleons

We present the first model independent test of additive quark model (AQM) predictions relating K⁺n_↑→K^*0p and p_↑p→Δ⁺⁺n reactions with polarized initial nucleons. The previously know AQM equalities and the new AQM inequalities are tested at 6 GeV/c in both s- and t-channel helicity to verify their frame independence. The data are close to the predicted AQM equalities and satisfy a stringent cubic inequality. The observed deviations from AQM equalities may reflect non-additive spin effects in hadron recombination.     

THE DUAL ABSORPTIVE MODE AND πP ELASTIC SCATTERING REVISITED

Using the Regge pole phase rule for contrilbutions to both amplitudes the DAM is applied to ^πp elastic scattering in the p_lab≥10 GeV/c and |t|≤0.8(GeV/c)² region. It is found that the DAM has a mixed success in describing ^πp scattering. The p contribution to both amplitudes is in accord with the DAM while the f-non-flip contribution does not have a peripheral zero.The Pomeron imaginary part is in accord with the DAM with a non-negligible Pomeron phase so that the DAM approximation Rep=O is unsatisfactory. There is also a Pomeron-flip contribution contrary to the expectation of the model. The O-flip contribution is taken into account and a small f-flip contribution i s also required.     

Influence of the In-Medium Quark Mass on the K+-Nucleus scattering

The influence of density-dependent quark masses, based on the Nambu-Jona-Lasinio model, on K⁺-nucleus scattering is investigated. Introduction of this density dependence is found to be a possible explanation for the missing theoretical K⁺-nucleus cross section     

ANALYSIS OF SOME HYPERCHARGE EXCHANGE REACTIONS OF THE TYPE 0-+1+/2→2++1+/2 at 4 GeV/c

The differential and integrated cross section data for the hypercharge exchange reactions ^πp→K°(1420)Λ, K ^- p→f°Λ and K ^- p→f^′Λ at 4 GeV/c are fitted by using as imple Regge pole model with phenorncnological residue functions. It is assumed that each of the two non-degenerate K^* and K^** trajectories, exchanged in this reaction, is coupled only to one of the two independent helicity amplitudes.     

Regge-pole description of γN→πN backward-scattering data

Baryon Regge-pole contributions to u-channel helicity amplitudes for the γN→πN processes are derived, with attention to kinematic singularities and threshold conditions. An N, Nγ and Δδ Regge-exchange model is proposed that describes the backward scattering data on γp→π^op and γp→π⁺n at high energy. The N and Nγ trajectories are found to be nearly degenerate, with residues in the ratio β(Nγ)/β(N)≈0.6. Structure in the differential cross sections is explained as dominance at small u giving way to dominance at large u. An isoscaar-isovector admixture for the γ-coupling to is required by the fits. The solution extrapolates through the mean γp→π^op 180^o differential cross section at intermediate energies, as required by duality.     

Charged Pion Form Factor Determination in the Range of Q^2= 0.6-1.6 （GeV／c）^2

Using the most recent differential cross section data for e-p quasi-elastic scattering, the charged pion formation and its form factor Fπ is calculated in the energy range of 2.4-4 GeV at Q^2 = 0.6-1.6 (GeV/c)^2. The functional dependence of the charged pion form factor to the separated cross section aL is investigated and compared to the previously determined result.     

Phenomenological use of the Callan-Symanzik equation

We find that the Callan-Symanzik equation with the intrinsic breaking term omitted suggests ansatz for the differential cross section in the high energy wide angle limit. The agreement with experimental data for the reactions ep → ep, π⁻p → π⁻p, pp → pp is very satisfactory.     

Quasi Three-Body Decay of D Meson

The aim of this work is to provide a phenomenological analysis of the contribution of D~0 meson to K*(892)~0π~+π~-(K*(892)~0-→π~+K~-), K~-π~+ω(ω-→π~+π~-π~0) and K~-π~+?(?(1020)-→ K~+K~-) quasi-three-body decays. The analysis of mentioned multi-body decays is such as to factorize into the three-body decay and several channels observed. Hadronic three-body decays receive both resonant and non-resonant contribution. Based on the factorization method, there are tree and emission annihilation diagrams for these decay modes. In the case of D~0 to vector pseudoscalar states appeared in factored terms, the matrix elements of the vector and axial vector currents between the D~0 and PV mesons can be computed by using D~(*+)pole. Considering the non-resonant and resonant amplitude in our computation,the theoretical values of the branching ratio are(9.78 ± 0.46) × 10~(-3),(2.74 ± 0.17) × 10~(-2), and(3.53 ± 0.23) × 10~(-5), while the experimental results of them are(9.9 ±2.3) × 10~(-3),(2.7 ± 0.5) × 10~(-2), and(4 ± 1.7) × 10~(-5) respectively. Comparing computational analysis values with experimental values show that our results are in approximately agreement with them.     

PROTON-AMTIPROTOM ELASTIC SCATTERING AT HIGH ENERGIES

The differential cross sections for high energy P P elastic scattering showing structure near -t=1.5 (GeV/c)² for P_L=50,100 and 200 GeV/c together with total cross sections for 50≤P_L≤280 GeV/c, and with -t extending up to 5(GeV/c)² have been fitted by using a dipole pomeron model.     

STUDY OF THE REACTION K-p → πo Λ

It is shown that at high energy all available data for differential and integrated cross sections and the Λ-polarization in the reaction K^-p → π^o Λ can be fitted by using a simple Regge pole model with phenomenological residue functions. The characteristics of helicity and helicity non-flip amplitudes are also examined.     

High Energy Proton-Proton Elastic Scattering in the Pomeron Exchange Model

We study high energy proton-proton elastic scattering in the framework of Pomeron exchange model. The cross section of the process are calculated without any free parameters. Our finding is that Pomeron exchange theory gives perfect fits to total cross section at the energy of √(s) higher than 10 GeV and to differential cross section at the momentum transfer |t| less than 1.5 GeV². For total cross section at lower energy √(s)<10 GeV and differential cross section at larger momentum transfer region of |t|>1.5 GeV², the Pomeron exchange theory needs to be improved.     

Pion-nucleon phase shifts below 270 MeV

Pion-nucleon phase shifts below 270 MeV are derived from fixed t-dispersion relations using as input the π⁺p total cross sections measured by Bugg et al. below 290 MeV and CERN phase shifts above that energy. No particular high-energy model is needed.

It is pointed out that the predicted d-wave phase shifts — in contradiction to those belonging to earlier phase-shift solutions — are in good agreement with partial-wave dispersion relations and recent information on the helicity amplitudes describing the process . Furthermore our prediction for the P₁₃ wave has very recently got strong support from the work by Bugg et al. on pion-nucleon charge-exchange scattering.     

(ΩΩ)0+ Dibaryon Productions in Central Au+Au Collisions at RHIC Energy (sNN)1/2 =130 GeV

Based on the measured transverse mass spectra of π^-, K^-, and p at the RHIC energy (s_NN)^1/2=130 GeV, di-omega productions from baryon-baryon reactions in hadronic matter are studied. Results about the >(ΩΩ)_0⁺ number show that the deeply bound state >(ΩΩ)_0⁺ can be observed at RHIC energies.     

A STUDY OF THE REACTION K-P→ΦΛ AC 4.2GeV/c

The high statistics differential cross section, polarisa-tion and density matrix data on K^-P→ΦΛ obtained by the AmsterdamCERN-Nijmegen-Oxford collaboration at 4.2GeV/C is analysed using a Regge pole model with evasive Regge contribu-tions. The exchanges invoked are the K*, K**, K,KA and K_Z The K*-K** exchanges are taken to be non-degenerate and a simplifying assumption on their couplings in O+ζ→O+ζ reactions, advocated recently by Saleem and collaborators, is generalised to the present case. We do not find any need for the K_B in fitting data.     

K+ Inelastic Scattering From 2+, 3- State of 12C at 800 MeV/c

The differential cross sections of the inelastic scattering 6f K⁺ at 800 MeV/c on 2⁺, 3^- excited states of ¹²C are calculated by means of the eikonal approximation and the collective coordinate. It seems that the 2⁺ state of ¹²C is quadrupole rotational state, the 3^- state of ¹²C is octupole vibrational state. The results are in agreement with experimental data.