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I discuss the prospects of using femtoscopy in high-energy protonproton and heavy-ion collisions to learn about the low-energy J/ψ-nucleon interaction. Femtoscopy is a technique that makes it possible to obtain spatiotemporal information on particle production sources at the femtometer scale through measurements of two-hadron momentum correlation functions. These correlation functions also provide information on low-energy hadron-hadron forces as final-state effects. In particular, such correlation functions give access to the forward scattering amplitude. One can express the forward amplitude as the product of the J/ψ chromopolarizability and the nucleon's average chromoelectric gluon distribution, the latter being relevant to the problem of the origin of the nucleon mass. I will present the results of a recent study using the information on the J/ψ-nucleon interaction from lattice QCD simulations to compute J/ψ-nucleon correlation functions. The calculated correlation functions show clear sensitivity to the final-state interaction. I conclude discussing open issues regarding the use of the effective range expansion formula to fit experimental data for small scattering lengths and large effective range parameters. [ABSTRACT FROM AUTHOR]

We review the achievements of the project C.9. Topics addressed include the magnetic moment of the ρ-meson, elastic pion-nucleon scattering in various settings of chiral perturbation theory, the reaction πN → ππN as well as new directions in chiral perturbation theory. [ABSTRACT FROM AUTHOR]

Ever since Weinberg’s seminal predictions of the pion–nucleon scattering amplitudes at threshold, this process has been of central interest for the study of chiral dynamics involving nucleons. The scattering lengths or the pion–nucleon σ-term are fundamental quantities characterizing the explicit breaking of chiral symmetry by means of the light quark masses. On the other hand, pion–nucleon dynamics also strongly affects the long-range part of nucleon–nucleon potentials, and hence has a far-reaching impact on nuclear physics. We discuss the fruitful combination of dispersion-theoretical methods, in the form of Roy–Steiner equations, with chiral dynamics to determine pion–nucleon scattering amplitudes at low energies with high precision. [ABSTRACT FROM AUTHOR]

Nuclear reactions, π−+A (A = C;W), at an incident beam momentum of 1:7 GeV/c were measured with the HADES setup at SIS18/GSI. Detailed investigations of the K+, K− and ϕ production off nuclei are connected to the study of hadron in-medium properties at nuclear saturation density. A contradictory role is played by the ϕ meson since the ϕN absorption cross-section is assumed to be small due to the OZI suppression which is in contrast to experimental observations. We present the analysis method to identify the ϕ meson exploiting the large K+K− branching ratio (≈ 50%). The correction for acceptance and effciency effects of the detector system will be discussed as well. [ABSTRACT FROM AUTHOR]

Recent achievements on the description of nuclear magnetic moments in the framework of covariant density functional theory using PC-PK1 interaction are reviewed by including the corrections from time-odd fields, one-pion exchange current and configuration mixing. By taking 17F and 207Tl as examples, the relativistic description for LS closed-shell nuclei and jj closed-shell nuclei plus or minus one nucleon are respectively demonstrated. It has been found that the time-odd fields, the one-pion exchange current and the configuration mixing corrections are important and work together to improve the description of experimental nuclear magnetic moments. [ABSTRACT FROM AUTHOR]

We discuss density corrections of the chiral condensate up to a NLO order using the chiral Ward identity and an in-medium chiral perturbation theory. The in-medium chiral condensate is calculated by a correlation function of the axial current and pseudoscalar density in the nuclear matter as a consequence of the chiral Ward identity. The correlation function is evaluated using the chiral perturbation theory with the hadronic quantities of pion-nucleon dynamics. We assume that the in-vacuum interaction vertices are known, which means that the in-vacuum loop corrections are renormalized to the tree chiral couplings by taking the values of the couplings in chiral Lagrangian as the physical values. We focus on density order in the physical quantities in our perturbative calculation. This study shows that the medium effects to the chiral condensate beyond the linear density come from density corrections to the πN sigma term. It implies that calculating the density dependence of the chiral condensate in nuclear matter is essentially equivalent to describe nuclear matter in chiral effective theory. [ABSTRACT FROM AUTHOR]

We have analyzed pion-nucleon scattering using the manifestly relativistic covariant framework of Infrared Regularization up to O (q3) in the chiral expansion, where q is a generic small momentum. We describe the low-energy phase shifts with a similar quality as previously achieved with Heavy Baryon Chiral Perturbation Theory, [Square_Root]s ≤ 1.14 GeV. We have unitarized the previous amplitudes and, as a result, the energy range where data are reproduced increases significantly. Finally we present our preliminary results for the same calculation in the Extended-On-Mass-Shell scheme. [ABSTRACT FROM AUTHOR]

We investigate the influence of new GRAAL Σ-beam asymmetry measurements on the neutron in multipole fits to the single-pion photoproduction database. Results are compared to those found with the addition of a double-polarization quantity associated with the sum rule. [ABSTRACT FROM AUTHOR]

We present the results on P11 resonances obtained with Dubna-Mainz-Taipei (DMT) dynamical model for pion-nucleon scattering and pion electromagnetic production. The extracted values agree well, in general, with PDG values. One pole is found corresponding to the Roper resonance and two more resonances are definitely needed in DMT model. We further find indication for a narrow P11 resonance at around 1700 MeV with a width ~ 50 MeV in both πN and γπ reactions. [ABSTRACT FROM AUTHOR]

We present recent studies on the transverse spin densities of the pion and nucleon within the framework of the chiral quark-(soliton) model, based on the calculation of the electromagnetic and tensor form factors of the pion and the nucleon. The results for the transverse spin densities of the quark inside a pion are in good agreement with the recent lattice data, while those of the nucleon show similar features to the lattice results. We also present the first results of the transverse spin densities of the strange quark inside a nucleon. [ABSTRACT FROM AUTHOR]

We present recent investigations on the properties of nucleons in nuclear matter and, in particular, nucleon electromagnetic form factors in the framework of the in-medium modified Skyrme model. Medium modifications are achieved by introducing the pion-nucleus optical potential for the pion fields in nuclear environment. In order to reproduce the bulk matter properties, the parametrization of the Skyrme term in the nuclear matter has been adjusted and the sensitivity of results to the pion-nucleus optical potential parameters are discussed. [ABSTRACT FROM AUTHOR]

The study of NN-interactions with production of 1S0 proton pairs (diprotons) provides a new approach to hadron interactions at intermediate energies. The use of the polarised COSY beams and the ANKE polarised internal target allows one to conduct single and double polarization experiments. A number of processes including pd→{pp}sn, production of one and two pions in pN collisions, and the pp→{pp}sγ process, have been investigated. Information on the near-threshold single pion production with formation of a diproton in the processes pp→{pp}sπ0 and pn→{pp}sπ- is urgently needed for further development of chiral perturbation theory. The measurements of dσ/dΩ, Ay and the spin-correlation coefficients Ax,x and Ax,z will permit an amplitude analysis that should provide a non-trivial test of the χPT predictions. A combined study of these processes will lead to the isolation of the strength parameter d of the four-nucleon-pion contact interaction in χPT. Preliminary ANKE results on dσ/dΩ and Ay in these processes are presented, and the future experimental programme is discussed. [ABSTRACT FROM AUTHOR]

The low-lying even-parity states of the nucleon are explored in lattice QCD using the PACS-CS collaboration 2+1-flavor dynamical-QCD gauge-field configurations. The established correlation-matrix approach is used, in which various fermion source and sink smearings are utilized to provide an effective basis of interpolating fields to span the space of low-lying energy eigenstates. Of particular interest is the nature of the first excited state of the nucleon, the N12+ Roper resonance of P11 pion-nucleon scattering. The Roper state of the present analysis approaches the physical mass, displaying significant chiral curvature at the lightest quark mass. These full QCD results, providing the world's first insight into the nucleon mass spectrum in the light-quark regime, are significantly different from those of quenched QCD and provide interesting insights into the dynamics of QCD. [ABSTRACT FROM AUTHOR]

Pion-nucleon scattering, pion photoproduction, and nucleon Compton scattering are analyzed within a scheme based on the chiral Lagrangian. Partial-wave amplitudes are obtained by an analytic extrapolation of subthreshold reaction amplitudes computed in chiral perturbation theory, where the constraints set by electromagnetic-gauge invariance, causality and unitarity are used to stabilize the extrapolation. Experimental data are reproduced up to energies [formula] in terms of the parameters relevant at order Q3. A striking puzzle caused by an old photon asymmetry measurement close to the pion production threshold is discussed. [ABSTRACT FROM AUTHOR]

In this talk I review the main features of the coherent/diffractive pion production by neutrinos on nuclei. The method is based on PCAC and relates the reaction boson+nucleus→pion+nucleus to elastic pion-nucleus scattering. Estimates for the expected rates and distributions in neutrino reactions are presented with the help of hadronic data. The absolute rates are significantly smaller than the older estimates [1] which brings theory in agreement with the neutral current measurements and the bounds in charged current reactions. [ABSTRACT FROM AUTHOR]

The existing models of baryons usually predict considerably more resonance (three or more in number) than it was found by investigation of elastic pion-nucleon scattering. This disagreement invites further investigation of the pion-nucleon interaction and among other things the measurement of spin rotation parameters A and R in the elastic pion-nucleon scattering. Recent experiments of the PNPI and PNPI-ITEP collaborations resolved a part of twofold ambiguities of the existing partial wave analyses (PWA). These results were used in the last PWA of the George Washington University group SP06. The proposal for the additional spin rotation parameters A and R measurement in the resonance region is motivated. Such additional measurements are necessary to resolve remaining twofold ambiguities of the existing PWAs. [ABSTRACT FROM AUTHOR]

The new form of current conservation is used for the analytical determination of the dipole magnetic moments of the Δ resonances in the pion-nucleon bremsstrahlung reaction π+N⇒γ′+π′+N′ [1]. This current conservation condition presents a modified Ward-Takahashi identity for the on shell πN bremsstrahlung amplitude. According to this identity the internal and external particle radiation parts of the πN bremsstrahlung amplitude have an opposite sign i.e. they contain terms which cancel each other. Therefore a screening of the internal and external particle radiation in the πN bremsstrahlung is generated. In particular it is shown, that the internal double A exchange diagram with the Δ-γ′Δ′ vertex cancel with the appropriate longitudinal part of the external particle radiation diagrams. This enables to obtain a model independent estimation of the dipole magnetic moment of Δ+ and Δ++ resonances μΔ through the anomalous magnetic moment of the proton μp as μΔ+ = MΔmpμp and μΔ++ = 32μΔ+ in agreement with the values obtained from the fit of the experimental cross section of the π+P→γ′π+P reaction. Considering pions and nucleons as bound (cluster) states of quarks in the usual quantum field theory [5,6,7,8] a generalization of the suggested approach is suggested [2]. The resulting equations for the external and internal particle radiation amplitudes of the πN bremsstrahlung reaction have the same form as in formulation without quark degrees of freedom [1]. Therefore the model independent estimation of the dipole magnetic moment of Δ+ and Δ++ resonances μΔ+/μp = MΔ/mp and μΔ++/μΔ+ = 32 in the usual local quantum field theory is preserved in the general quantum field formulation with the quark degrees of freedom. [ABSTRACT FROM AUTHOR]

A large single transverse spin asymmetry of forward neutron production in polarized pp collision was discovered at RHIC-IP12 experiment. The origin of its asymmetry is very interesting question. More precise forward neutron measurement in PHENIX will be first time to discuss the polarized phenomenon of neutron production. Results of the cross section and single transverse spin asymmetry of forward neutron production at [formula] are presented. It may prefer the one pion exchange model which is successful to explain the forward neutron cross section. © 2007 American Institute of Physics [ABSTRACT FROM AUTHOR]

We present an overview of our efforts to analyze pion-nucleon elastic scattering data, along with data from related photo- and electroproduction reactions, in order to study the baryon spectrum. We then focus on the Δ(1232) resonance. Fits to pion photo- and electroproduction data have been used to extract values for the REM = E2/M1 and RSM = S2/M1 ratios as functions of Q2. These results are compared to other recent determinations. © 2007 American Institute of Physics [ABSTRACT FROM AUTHOR]

Quasifree single-pion photoproduction on the deuteron via the exclusive reaction d(γ, π0n)p is studied in the Δ(1232)-resonance region including all leading πNN effects. Special emphasizes are given to single spin observables. The elementary pion photoproduction amplitude from free nucleons is taken from the dynamical model of Sato and Lee (SL model) [Phys. Rev. C54 (1996) 2660]. The interactions in the final two-body subsystems are taken in separable form. Final-state interaction effects are found to be significant and lead to an improved agreement with the most recent experimental data from Brookhaven National Laboratory (LEGS-exp.L3b). © 2007 American Institute of Physics [ABSTRACT FROM AUTHOR]

The phenomena of confinement and dynamical chiral symmetry breaking are basic to understanding hadron observables. They can be explored using Dyson-Schwinger equations. The existence of a systematic, nonperturbative and symmetry preserving truncation of these equations enables the proof of exact results in QCD, and their illustration using simple but accurate models. We provide a sketch of the material qualitative and quantitative success that has been achieved in the study of pseudoscalar and vector mesons. Efforts are now turning to the study of baryons, which we exemplify via a calculation of nucleon weak and pionic form factors. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]

The production of baryon and mesons in the RHIC heavy-ion experiments has received a lot of attention lately. Although not widely known, the pp data measured concurrently with heavy ion collisions do not find a convincing explanation in terms of simple models. We present the results of an afterburner to Pythia and Hijing event generators, simulating radial flow which seems to qualitatively explain the experimental results when applied to the pp collision data from RHIC at 200 GeV center-of-mass energy. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]

Measurements are reported of the production of dijet events with a leading neutron in ep interactions at HERA. Differential cross sections for photoproduction and DIS are presented. LO QCD simulation programs and NLO perturbative QCD calculations are compared with the measurements. Models in which the real or virtual photon interacts with a parton of an exchanged pion are found to be in good agreement with the measured cross sections. The fraction of leading neutron dijet events with respect to all dijet events is also determined. © 2005 American Institute of Physics [ABSTRACT FROM AUTHOR]

I draw attention to a recent breakthrough in the field of low energy pion physics: the consequences of the hidden symmetry of the QCD Hamiltonian have successfully been incorporated in the general dispersive framework for the &pie;&pie; scattering amplitude, which is due to Roy. The meagre experimental information about the imaginary parts at and above 0.8 GeV suffices to unambiguously and accurately pin down the scattering amplitude at lower energies. The recent Brookhaven data on the reaction K → &pie;&pie;ev provide a significant test of the theory. They imply that the Gell-Mann-Oakes-Renner relation is approximately valid - the bulk of the pion mass indeed originates in the quark condensate. [ABSTRACT FROM AUTHOR]

Recently we have succeeded in observing the 1s and 2p bound pionic states in [sup 205]Pb nucleus as well separated peaks in the excitation spectrum of the [sup 206]Pb(d,[sup 3]He) reaction. The observed spectrum agreed quite well with the theoretical prediction where the formation cross section was calculated for the deeply bound pionic states [1]. These states are accommodated in proximity to the nuclear surface as halo states in a potential provided by the attractive Coulomb and the repulsive core. The binding energies and the widths were precisely determined, and the values were used to deduce the unknown s-wave part of the π-nucleus interaction and to translate it to the effective pion mass in nuclear matter. © 2002 American Institute of Physics. [ABSTRACT FROM AUTHOR]