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I overview our recent activity with the Argonne-Osaka dynamical coupled-channels (DCC) approach that provides a unified description of various electroweak meson productions on single nucleon and nucleus. First I discuss the DCC model of a single nucleon. The DCC model has been developed through a comprehensive analysis of πN, γN → πN, ηN, KΛ, KΣ reaction data. The model has been further extended to finite Q2 region by analyzing pion electroproduction data, and to neutrino-induced reactions using the PCAC relation. Next I discuss applications of the DCC model to electroweak meson productions on the deuteron. We consider impulse mechanism supplemented by final state interactions (FSI) due to NN and meson-nucleon rescatterings. Using this model, I discuss FSI corrections needed to extract γ-neutron reaction observables from γd → πNN, and a novel method to extract ηN scattering length from γd → ηpn. I also discuss FSI corrections on the existing neutrino-nucleon pion production data that had been extracted from neutrino-deuteron data. [ABSTRACT FROM AUTHOR]

We have calculated the mass spectra and digamma decay width of the dimesonic (meson-antimeson molecule) states in the heavy-light meson sector in the potential model framework. The interaction potential of the systems are assumed to be the Yukawa-like potential with the one pion exchange and sigma exchange potential. The calculated masss spectra of dimesonic states are in good agreement with compared states like Ds1(2536), DsJ *(2860) and DsJ(3040). [ABSTRACT FROM AUTHOR]

Spin-isospin response in exotic nuclear systems is investigated. It is found that in some nuclei excitations with pionic quantum numbers (0-, 1+, 2-, ...) appear at very low energies with large transition probabilities, which is an indication of the vicinity of the onset of pion condensation. As an example, 2- components of the spin-dipole resonance in 78Ni and 132Sn are considered. The existence of such modes points out to the necessity of taking into account their coupling to other elementary modes of excitation, e.g. single-quasiparticle ones. This coupling is introduced in the theory for the first time. Thereby, both rho-meson and pion-exchange contributions to the nucleon-nucleon interaction are included in the relativistic framework beyond the Hartree-Fock approximation. Namely, classes of Feynman diagrams are selected according to their significance for nuclear spectroscopic characteristics, such as single-particle energies and strength functions, and included into the nucleonic self-energy in all orders of meson-exchange. As an illustration, the impact of these new contributions on the single-particle energies of 100Sn is discussed. [ABSTRACT FROM AUTHOR]

Small angle electron scattering with intense electron beams opens up the possibility of performing almost real photon induced reactions with thin, polarized hydrogen and few body targets, allowing for the detection of low energy charged particles. This promises to be much more effective than conventional photon tagging techniques. For photo-pion reactions some fundamental new possibilities include: tests of charge symmetry in the N-N system by measurement of the neutron-neutron scattering length ann in the &ggrD → π+nn reaction; tests of isospin breaking due to the mass difference of the up and down quarks; measurements with polarized targets are sensitive to πN phase shifts and will test the validity of the Fermi-Watson (final state interaction) theorem. All of these experiments will test the accuracy and energy region of validity of chiral effective theories. [ABSTRACT FROM AUTHOR]

We report a study of the central exclusive production of π+π- and K+K- pairs in high energy hadron-hadron collisions. The amplitude is calculated in the Regge approach including both pomeron and secondary reggeon exchanges and absorption effects due to proton-proton interaction and ππ (KK) rescattering. We discuss a measurement of exclusive production of a scalar χc0 meson via χc0→π+π-, K+K- decay. We find that the relative contribution of resonance states and the ππ (KK) continuum strongly depend on the cut on pion (kaon) transverse momentum. We compare the results with the existing experimental data and present predictions for the RHIC, Tevatron and LHC colliders. We discuss also the f2 (1270) meson production mediated by an effective tensor pomeron exchanges. [ABSTRACT FROM AUTHOR]

Problems in the construction of amplitudes from meson photoproduction data are examined. Methods are applied to pion and kaon photoproduction data with the goal of minimal model bias. [ABSTRACT FROM AUTHOR]

An overview of current theoretical approaches to generate meson-baryon reaction amplitudes is given. [ABSTRACT FROM AUTHOR]

Nuclear medium effects in the weak structure functions F2(x,Q2) and F3(x,Q2) have been studied for deep inelastic neutrino/antineutrino reactions in iron nucleus by taking into account Fermi motion, binding, pion and rho meson cloud contributions, target mass correction, shadowing and anti-shadowing corrections. The calculations have been performed in a local density approximation using relativistic nuclear spectral functions which include nucleon correlations. Using these structure functions we have obtained the ratio RF2,F3A(x,Q2) = 2F2,3A(x,Q2)AF2,3D(x,Q2), the differential scattering cross section 1Ed2σdxdy and the total scattering cross section σ. The results of our numerical calculations in 56Fe are compared with the experimental results of NuTeV and CDHSW collaborations. [ABSTRACT FROM AUTHOR]

We demonstrate the equivalence of the light-front, equal-time and covariant formulations in meson-baryon interactions. In particular, we discuss the self-energy Σ of a nucleon dressed by pion loops with the pseudovector πNN coupling. It is shown that the leading nonanalytic behavior of Σ is equivalent whichever formulations are used for the derivation. [ABSTRACT FROM AUTHOR]

Pion exchange in S-wave between hadrons that are themselves in S-wave may result in strong physical effects. Previously it was conjectured that this dynamics could lead to deeply bound quasi-molecular states. More recent studies suggest that the dynamics will result in a large non-resonant background rather than in bound states. [ABSTRACT FROM AUTHOR]

A fesibility study to explore the capability of the WILLI detector to observe the solar events/activity by recording the muon intensity at ground level is presented. The WILLI detector, set up in National Institute of Physics and Nuclear Engineering, Bucharest, is a 1 m2 incident area sampling calorimeter. It can measure simultaneously muon events with the muon energy >=0.4 GeV and, if the muons are stopped in the detector, and muon energy between 0.4=0.4 GeV, a modulation of the muon intensity as a diurnal variation is observed. Muon events for a smaller energy range (0.4-0.6 GeV) seem to exhibit an aperiodic variation of the muon intensity, which could be correlated with magnetic activity indicated by the planetary Kp index. [ABSTRACT FROM AUTHOR]

The PRIMEX collaboration at Jefferson Lab is completing an experimental analysis to obtain a precision measurement of the neutral pion lifetime. Results from the experiment will be presented and comparisons made with the chiral anomaly prediction and NLO calculations. An extension of the experiment to 12 GeV for measurements of the η and η′ radiative widths is discussed. [ABSTRACT FROM AUTHOR]

The relationship between mesonic correlations and quantum condensates in the quark matter phase diagram is explored within a quantum field theoretical approach of the Nambu and Jona-Lasinio (NJL) type. Mean-field values in the scalar meson and diquark channels are order parameters signaling the occurrence of quark condensates, entailing chiral symmetry breaking (χSB) and color superconductivity (2SC) in quark matter. We investigate the spectral properties of scalar and pseudoscalar meson excitations in the phase diagram in Gaussian approximation and show that outside the χSB region where the pion is a zero-width bound state, there are two regions where it can be considered as a quasi-bound state with a lifetime exceeding that of a typical heavy-ion collision fireball: (A) the high-temperature χSB crossover region at low densities and (B) the high-density color superconducting phase at temperatures below 100 MeV. [ABSTRACT FROM AUTHOR]

The newly introduced Transition Distribution Amplitudes (TDAs) are discussed for the π-γ transitions. Relations between π-γ and γ-π TDAs for different cases are given. Numerical values for the π-γ TDAs in different models are compared. GPD’s features are extended to TDAs and the role of PCAC highlighted. We give hints for the evaluation of cross sections for meson pair production in our approach. [ABSTRACT FROM AUTHOR]

Recent results are presented for quasifree pion photoproduction off the deuteron in the energy region from threshold up to the Δ(1232)-resonance with inclusion of all leading πNN effects. Final-state interaction effects are investigated and their role in polarized and unpolarized observables are found to be significant. The sensitivity of results to the elementary N(γ,π)N operator is discussed and considerable dependence is found. We expect that these results may be useful to interpret the recent measurements from LEGS, A2 and GDH Collaborations. [ABSTRACT FROM AUTHOR]

The implementation of tensor sources in Chiral Lagrangians allows the computation of Green functions and form factors involving tensor currents, that is, quark bilinears of the form qiσμνqj. Whereas only four new terms show up at O(p4), we find around a hundred of them at O(p6). So it becomes essential to ensure that this set o operators is indeed minimas and non-redundant (i.e., it is a basis). We discuss two phenomenological applications in the context of vector meson resonances and the radiative pion decay. [ABSTRACT FROM AUTHOR]

Predictions for invariant mass distributions of electron and pion pairs from the η→π+π-e+e- decay have been recently given in a chiral unitary approach. They have to wait for experimental verification since up to now only few events were observed. The WASA-at-COSY collaboration has started investigations of this channel with high statistics. The analysis tools could also be used in future for of the analogous decay of the η′ meson. [ABSTRACT FROM AUTHOR]

The goal of the DIRAC experiment at CERN (PS212) is to measure the π+π- atom lifetime with 10% precision. Such a measurement would yield a precision of 5% on the value of the S-wave ππ scattering lengths combination |a0 - a2|. Based on part of the collected data we present a first result on the lifetime, τ = [2.91 -0.62+0.49] × 10-15 s, and discuss the major systematic errors. This lifetime corresponds to |a0 - a2| = 0.264 -0.020+0.033 mπ-1. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]

A combined analysis of new π0 and η photoproduction data from CB-ELSA collaboration was performed including the earlier data from SAID data base, new data on beam asymmetry from the GRAAL collaboration and data on γp → KΛ and KΣ. Three baryon resonances have a substantial coupling to ηN, the well known N(1535)S11, N(1720)P13 and the newly observed N(2070)D15 resonance. A new P11 state with mass 1840 MeV and width 140 MeV was observed contributing to most of the fitted reactions. The data also demand the presence of two D13 states at 1870 and 2170 MeV. The properties of observed states and their contributions to different observables are discussed. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]

We study the Λ(1520) resonance in a coupled channel approach involving the πΣ(1385), K[cap_xi](1530), KN and πΣ channels. Implementing unitarity in coupled channels, we make an analysis of the relative importance of the different mechanisms which contribute to the dynamical structure of this resonance. From experimental information on some partial wave amplitudes and constraints imposed by unitarity, we get a comprehensive description of the amplitudes and hence the couplings to the different channels. We test these amplitudes in different reactions like K-p → Λππ, γp → K+K-p, γp → K+π0π0Λ and π-p → K0K-p and find a fair agreement with the experimental data. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]

The K-p → π0π0Σ0 reaction is studied within a chiral unitary model. The distribution of π0Σ0 states forming the Λ(1405) shows, in agreement with a recent experiment, a peak at 1420 MeV and a relatively narrow width of Γ = 38 MeV. We use these data in combination with those of the π-p → K0πΣ reaction and elements of chiral unitary theory to prove that there are two Λ(1405) states instead of one as so far assumed. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]

A new set of experiments on meson photoproduction up to beam energies of 1.5 GeV is being planned for the MAMI-C accelerator in Mainz (Germany). The experimental apparatus consists of the Crystal Ball multiphoton spectrometer together with the TAPS detector as a forward wall and a central tracker based on the DAPHNE-type cylindrical wire chambers and a central tracker. This configuration provides a geometrical acceptance approaching the full acceptance with good energy and angular resolutions for photons as well as a good angular resolution for charged particles. Using this set-up, a first round of experiments have already been performed at the existing MAMI-B facility (photon energies up to 820 MeV) to determine basic properties of hadrons like the magnetic moment of the Δ+(1232) resonance, branching ratios/upper limits for various rare and forbidden eta-meson decays, test of low-energy theorems for single pion photoproduction. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]

The measurement of the electric (απ) and magnetic (βπ) pion polarizabilities supplies a significant test of QCD predictions in particular in the framework of the chiral perturbation theory. In this perspective we have measured with the COMPASS spectrometer the t-dependence of the cross section for the reactions: π- + Z → π- + Z + γ, and μ- + Z → μ- + Z + γ selecting events corresponding to the Compton πγ and μγ scattering respectively. From a fit of the data of the first reaction we can extract απ and βπ, from those of the second the point-like contribution. This procedure minimizes the systematic errors. Details on the experiment and the present status of the analysis of the data collected in 2004 will be discussed. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]

Using the collected sample of 200 million minimum-bias proton-nucleus interactions at 41.6 GeV centre-of-mass energy, HERA-B is measuring the magnitudes of several inclusive particle productions. This contribution reports on preliminary measurements of the D-meson and J/ψ production cross sections and compares them with the current experimental situation. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]

Experiments with the CMD-2 detector on VEPP-2M collider were carried out during 1992 – 2000. The total integrated luminosity of 33 pb-1 has been collected. The results of the measurement of electron positron annihilation cross-sections to hadrons in the whole VEPP-2M energy range are presented. Among them the new measurement of the pion formfactor in the whole energy range that confirms our previous result with the same systematic error 0.6% and new data on three, four pion and kaon production on [lowercase_phi_synonym]-meson and above. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]

The π+π- S-wave model is constructed in the course of the Partial Wave Analysis of the data on the reaction π-A → A′π+π-π-. Its structure, including the narrow resonances f0(980) and f0(1500) as well as broad “objects” [variant_greek_epsilon](1300) and σ(500), is discussed. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]

D meson 3-body hadronic decay data in the past were analyzed with Breit-Wigner amplitude fits. However, the complicated dynamics of the final states is known from previous studies to be poorly described by Breit-Wigner models. This short paper discusses work within CLEO to use coupled channel techniques to describe these decays. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]

We review our evaluation of forward dispersion relations for direct fits to the different, and often conflicting, ππ scattering experimental analyses. We find that some of the most commonly used data sets do not satisfy these constraints by several standard deviations. We also provide a consistent ππ amplitude by improving a global fit to data with these dispersion relations. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]

Chiral symmetry and unitarization are combined into generalized Breit-Wigner expressions describing scalar resonances, which contain free parameters and allow flexible descriptions of masses, widths and pole positions. This theoretical tool is especially designed to be used in analyses of low-energy data. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]

We estimate final state interactions in the B-meson decays into two pions by the Regge model. We take into account Pomeron exchange and the leading Regge trajectories that can be related to the final state. In the B → π0π0 and B → π+π- channels the effect produces a better agreement between theory and experiment. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]

We propose a holographic dual of QCD with massless flavors on the basis of a D4/D8-brane configuration within a probe approximation. We are led to a five-dimensional Yang-Mills theory on a curved space-time along with a Chern-Simons five-form on it, both of which provide us with a unifying framework to study the massless pion and an infinite number of massive vector mesons. We make sample computations of the physical quantities that involve the mesons and compare them with the experimental data. It is found that most of the results of this model are compatible with the experiments. © 2005 American Institute of Physics [ABSTRACT FROM AUTHOR]

The PHENIX experiment at RHIC has measured neutral pion, eta, and direct photon production in √sNN = 200 GeV p+p and Au+Au collisions. The neutral pion and direct photon yields in p+p collisions are well described by NLO pQCD predictions. In Au+Au collisions the neutral pion yield is suppressed as compared to expectations from p+p collisions, with a suppression which increases with increasing nuclear overlap. However, the direct photon yield shows no centrality dependent suppression, indicating that the pion suppression is due to a final state effect, such as parton energy loss in the excited final state. [ABSTRACT FROM AUTHOR]

The γn → π-p and γp → π+n reactions are essential probes of the transition from meson-nucleon degrees of freedom to quark-gluon degrees of freedom in exclusive processes. The cross sections of these processes are also advantageous, for the investigation of oscillatory behavior around the quark counting prediction, since they decrease relatively slower with energy compared with other photon-induced processes. In this talk, we discuss recent results on the γp → π+n and γn → π-p processes from Jefferson Lab experiment E94-104. We also discuss a new experiment in which singles γp → π+n measurement from hydrogen, and coincidence γn → π-p measurements at the quasifree kinematics from deuterium for center-of-mass energies between 2.3 GeV to 3.4 GeV in fine steps at a center-of-mass angle of 90° are planned. The proposed measurement will allow a detailed investigation of the oscillatory scaling behavior in photopion production processes. © 2005 American Institute of Physics [ABSTRACT FROM AUTHOR]

A preliminary study of the pion decay channel in the US neutrino factory design has been completed, assuming a 1 MW beam of 16 GeV protons incident on the graphite target described in the first neutrino factory feasibility study. Preliminary data suggests that improvements in adiabaticity and increased field strength in the decay channel can increase muon yields as much as 20%, and possible more. The data also suggests that the muon beam can possibly be captured into a smaller emittance if a higher field strength is used in the decay channel solenoids. © 2004 American Institute of Physics [ABSTRACT FROM AUTHOR]

An analytical model is developed to describe the longitudinal phase space of a hybrid beam of pions and decay muons. © 2004 American Institute of Physics [ABSTRACT FROM AUTHOR]

We study the radiative φ decay into π0π0γ and π0ηγ taking into account mechanisms in which there are two sequential vector-vector-pseudoscalar or axial-vector-vector-pseudoscalar steps followed by the coupling of a vector meson to the photon, considering the final state interaction of the two mesons. There are other mechanisms in which two kaons are produced through the same sequential mechanisms or from φ decay into two kaons and then undergo final state interaction leading to the final pair of pions or π0η, this latter mechanism being the leading one. [ABSTRACT FROM AUTHOR]

A program to measure the two-pion production in nucleon-nucleon collisions exclusively and in all channels from threshold up to Tp = 1360 MeV has been started at CELSIUS-WASA. First preliminary results for ppπ+π¯ and ppπ0π0 channels are presented. In the near-threshold region they are consistent with a dominance of the Roper excitation and its successive decay into Nσ and Δπ channels. At energies Tp > 1 GeV we observe a very different behavior, which is at variance with theoretical predictions. At COSY-TOF exclusive measurements of the pp → ppπ+π¯ reaction have been carried out with polarized beam. Preliminary results show non-zero analyzing powers which point to a sizeable admixture of l ≠ 0 partial waves indicating possibly an influence of the ρ-channel. [ABSTRACT FROM AUTHOR]

In this talk we demonstrate the results of application of the perturbative effective theory formaism developed in papers [1]–[6] to the calculation of πN elastic scattering amplitude. Restrictions on the contributing resonance parameters are obtained and the low energy coefficients are calculated. [ABSTRACT FROM AUTHOR]

Various exclusive and inclusive decays of B mesons are studied, at present, with dedicated experiments at ‘B factories’. In order to compete with the experimental accuracy, we need a reliable theoretical framework to compute strong interaction effects in a hadronic environment. I discuss how the separation of (perturbatively calculable) short-distance QCD effects from (non-perturbative) long-distance phenomena helps to obtain precise theoretical predictions. [ABSTRACT FROM AUTHOR]

The DIRAC experiment at CERN is presently measuring the lifetime of the pionium atom, a bound state of a π+ and π- meson. The isospin 0 and 2 scattering length difference will be determined unambiguously once the value of the lifetime is known. In what follows we describe the present status of the experiment, the experimental goals and the first results. © 2004 American Institute of Physics [ABSTRACT FROM AUTHOR]

Photo-production of excited mesons in the 1 – 2 GeV mass range decaying via multi-pion or multi-kaon emission has been investigated at the TJNAF1 experiment E01-017 (g6c) in the 4.8 – 5.4 GeV photon beam energy range. The main objective of the experiment is to extract resonance parameters of the produced states by way of a Partial Wave Analysis (PWA) technique. In this paper, we will focus on the general characteristics of the data distributions in both the neutral and charged 3-pion final states, i.e. π+π-π0 and π+π+π-. © 2004 American Institute of Physics [ABSTRACT FROM AUTHOR]

A simplified 1D (one-dimensional) model for a generalized 3N system is considered, as a testing ground for the explicit treatment of the meson dynamics in this system. We focus attention on the irreducible diagrams generated by the pion dynamics in the 3N system, and in particular to a new type of three-nucleon force discussed recently in the literature, and generated by the one-pionexchange mechanism in presence of a nucleon-nucleon correlation. It is found that these new terms in the simplified model have an approximately 30% effect compared to the standard three-nucleon force terms in a 'Triton' binding energy calculation. It is suggested that this effect should also not be ignored in realistic calculations. A simplified 1D (one-dimensional) model for a generalized 3N system is considered, as a testing ground for the explicit treatment of the meson dynamics in this system. We focus attention on the irreducible diagrams generated by the pion dynamics in the 3N system, and in particular to a new type of three-nucleon force discussed recently in the literature, and generated by the one-pionexchange mechanism in presence of a nucleon-nucleon correlation. It is found that these new terms in the simplified model have an approximately 30% effect compared to the standard three-nucleon force terms in a 'Triton' binding energy calculation. It is suggested that this effect should also not be ignored in realistic calculations. [ABSTRACT FROM AUTHOR]

We take an approach to the A nonmesonic weak decay in nuclei based on the exchange of mesons. The one pion and one kaon exchange are considered, together with the exchange of two pions, either correlated, leading to an important scalar-isoscalar exchange (σ-like exchange), or uncorrelated (box diagrams). A drastic reduction of the OPE results for the Γ[sub n]/Γ[sub p] ratio is obtained and the new results are compatible with all present experiments within errors. The absolute rates obtained for different nuclei are also in fair agreement with experiment. [ABSTRACT FROM AUTHOR]

Pion and η production on the deuteron are studied at energies in the vicinity of the absolute threshold. The data are expected to be sensitive to high momentum components in the deuteron wavefunction as well as to two step processes. © 2000 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Assesses the approach to meson production in proton-proton collisions near threshold T-matrices. Computation of the threshold amplitude; Details of the tree level and one-loop pion exchanges of T-matrix; Effects of heavy meson exchanges on proton-proton collisions.

A cartoon of the Effective Field Theory of many nucleon systems is drawn, concentrating on Compton scattering in the two nucleon system, and on nd scattering in the three body system. © 2000 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Generalized Parton Distributions (GPDs) offer a new way to access quark and gluon nucleon structure. The nucleon-to-meson transition distribution amplitudes (TDAs) are extensions of the GPD concept to three quark operators. In this talk we report the first preliminary results of studies of the reaction ep → epπ0 using the CEBAF Large Acceptance Spectrometer (CLAS) at Jefferson Lab with an electron beam energy of 5.75 GeV. Differential cross sections were extracted for 1.5 < Q2 < 4.5 GeV2, 0.1 < xB < 0.6 and -t up to 6.0 GeV2 in non-resonant region (W > 2.0 GeV). Results will be discussed in the framework of a u-channel TDA model. [ABSTRACT FROM AUTHOR]

Scalar-isoscalar states (JPC = 0++) are analyzed within the large-Nc Regge approach. We find that the lightest f0(600) scalar-isoscalar state fits very well into the pattern of the radial Regge trajectory. We confirm the obtained mass values from an analysis of the pion and nucleon spin-0 gravitational form factors, recently measured on the lattice. We find that a simple two-state model suggests a meson nature of f0(600), and a glueball nature of f0(980), which naturally explains the ratios of various coupling constants. Finally, matching to the OPE requires a fine-tuned mass condition of the vanishing dimension-2 condensate in the Regge approach with infinitely many scalar-isoscalar states. [ABSTRACT FROM AUTHOR]

The pion mass dependence of the pion vector form factor is investigated using the Omnès representation. Our prediction agrees with later lattice results quite well. The nice agreement of the pion mass dependence of the scattering lengths of the charmed mesons and light pseudoscalar mesons suggests that the Ds0(2317)* be a DK bound state. Furthermore, it is argued that the kaon mass dependence of a kaonic bound state should be linear, and can be used as a criterion in determining the nature of such a bound state on lattice. [ABSTRACT FROM AUTHOR]

We construct a new framework in the relativistic Hartree-Fock approximation with the form factor and short range correlation (RHFU) to study the properties of nuclear matter. The unitary correlation operator method (UCOM) is used to treat the short range correlation. With this model, we can completely reproduce the equation of state of pure neutron matter in the Dirac Brueckner-Hartree-Fock theory with Bonn potential. We also discuss the symmetric nuclear matter with the RHFU model. The contribution of ρ meson is cut down largely by the effect of form factor of the size in the Bonn potential. The short range correlation has very important influence on the Fock energies of pion and ρ meson. [ABSTRACT FROM AUTHOR]