OZI Violation Research Articles

Cornucopia of Antineutrons and Hyperons from a Super J/ψ Factory for Next-Generation Nuclear and Particle Physics High-Precision Experiments.

In order to study the interactions and structure of various types of matter, one typically needs to carry out scattering experiments utilizing many different particles as projectiles. Whereas beams of e^{±}, μ^{±}, π^{±}, K^{±}, protons, antiprotons, and various heavy ions have been produced and have enabled many scientific breakthroughs, beams of antineutrons, hyperons (Λ, Σ, and Ξ) and their antiparticles are typically not easy to obtain. Here we point out and investigate a new high-quality source of these particles: a super-J/ψ factory with the capability of accumulating trillions of J/ψ decays each year. In the relevant J/ψ decays, the desired particle is produced together with other final-state particles that can be tagged. This allows accurate determination of the flux and momentum of the projectile, enabling unprecedented precision in the study of the corresponding interactions with a broad range of targets. These novel high-statistics sources of baryons and antibaryons with precisely known kinematics open fresh opportunities for applications in particle and nuclear physics, including antinucleon-nucleon interaction, a nonvalence ss[over ¯] component of the nucleon, (anti)hyperon-nucleon interaction, OZI violation, (multistrange) hypernuclei, exotic light hadron spectroscopy, and many others, as well as calibration of MonteCarlo simulation for hadronic and medical physics.

Charmonium Hadronic Decays and the OZI Rule Violation Effects

We discuss the scalar meson mixing scenario and present an OZI rule violation mechanism for understanding the scalar productions in charmoium hadronic decays. We stress that the OZI violation could play a key role in disentangling the structure of the scalars: f0(1370), f0(1500) and f0(1710).

Improved analysis ofJ/ψdecays into a vector meson and two pseudoscalars

Recently, the BES collaboration has published an extensive partial-wave analysis of experimental data on $J/\ensuremath{\psi}\ensuremath{\rightarrow}\ensuremath{\phi}{\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}$, $J/\ensuremath{\psi}\ensuremath{\rightarrow}\ensuremath{\omega}{\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}$, $J/\ensuremath{\psi}\ensuremath{\rightarrow}\ensuremath{\phi}{K}^{+}{K}^{\ensuremath{-}}$ and $J/\ensuremath{\psi}\ensuremath{\rightarrow}\ensuremath{\omega}{K}^{+}{K}^{\ensuremath{-}}$. These new results are analyzed here, with full account of detection efficiencies, in the framework of a chiral unitary description with coupled-channel final state interactions between $\ensuremath{\pi}\ensuremath{\pi}$ and $K\overline{K}$ pairs. The emission of a dimeson pair is described in terms of the strange and nonstrange scalar form factors of the pion and the kaon, which include the final state interaction and are constrained by unitarity and by matching to the next-to-leading-order chiral expressions. This procedure allows for a calculation of the $S$-wave component of the dimeson spectrum including the ${f}_{0}(980)$ resonance, and for an estimation of the low-energy constants of Chiral Perturbation Theory, in particular, the large ${N}_{c}$ suppressed constants ${L}_{4}^{r}$ and ${L}_{6}^{r}$. The decays in question are also sensitive to physics associated with OZI violation in the ${0}^{++}$ channel. It is found that the $S$-wave contributions to $\ensuremath{\phi}{\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}$, $\ensuremath{\phi}{K}^{+}{K}^{\ensuremath{-}}$ and $\ensuremath{\omega}{\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}$ given by the BES partial-wave analysis may be very well fitted up to a dimeson center-of-mass energy of $\ensuremath{\sim}1.2\text{ }\text{ }\mathrm{GeV}$, for a large and positive value of ${L}_{4}^{r}$ and a value of ${L}_{6}^{r}$ compatible with zero. An accurate determination of the amount of OZI violation in the $J/\ensuremath{\psi}\ensuremath{\rightarrow}\ensuremath{\phi}{\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}$ decay is achieved, and the $S$-wave contribution to $\ensuremath{\omega}{K}^{+}{K}^{\ensuremath{-}}$ near threshold is predicted.

VECTOR MESON PRODUCTION IN COLLISIONS OF NUCLEONS

The production of vector mesons in collisions between nucleons is studied in order to address a variety of issues concerning nucleon-nucleon interaction, reaction mechanism and properties of baryons. These studies are summarized with emphasis on the most recent experiments at the Time-of-Flight spectrometer TOF and results obtained at the COoler SYnchrotron COSY in Jülich. While currently the open questions regarding the so-called OZI violation, its relation to the meson exchange picture and the relative importance of contributions to the production mechanism from various channels within this formalism are still unresolved, the present-day experiments hold the potential to clarify the situation greatly. Possible extensions of the experimental program on vector mesons using 4π detection techniques for charged as well as neutral particles, in particular π0, are discussed.

Instantons and the spin of the nucleon

Motivated by measurements of the flavor singlet axial coupling constant of the nucleon in polarized deep inelastic scattering we study the contribution of instantons to OZI violation in the axial-vector channel. We consider, in particular, the f_1-a_1 meson splitting, the flavor singlet and triplet axial coupling of a constituent quark, and the axial coupling constant of the nucleon. We show that instantons provide a short distance contribution to OZI violating correlation functions which is repulsive in the f_1 meson channel and adds to the flavor singlet three-point function of a constituent quark. We also show that the sign of this contribution is determined by positivity arguments. We compute long distance contributions using numerical simulations of the instanton liquid. We find that the iso-vector axial coupling constant of a constituent quark is (g_A^3)_Q=0.9 and that of a nucleon is g_A^3=1.28, in good agreement with experiment. The flavor singlet coupling of a quark is close to one, while that of a nucleon is suppressed, g_A^0=0.77. However, this number is larger than the experimental value g_A^0=(0.28-0.41).

Probing proton strangeness with time-like virtual Compton scattering

We document that p(γ,e+e−)p measurements will yield new, important information about the off-shell time-like nucleon form factors, especially in the φ meson region (q2=M2φ) governing the φN couplings gV,TφNN. Calculations for p(γ,e+e−)p, utilizing vector meson dominance, predict measurable φ enhancements at high |t| compared to the expected φ background production from π, η and Pomeron exchange. The φ form factor contribution generates a novel experimental signature for OZI violation and the proton strangeness content. The φN couplings are determined independently from a combined analysis of the neutron electric form factor and recent high |t| φ photoproduction. The π, η and Pomeron transition form factors are also predicted and the observed π and η transition moments are reproduced.

Chiral Dynamics with Strange Quarks: Mysteries and Opportunities

Recent developments and open issues in chiral dynamics with strange quarks are reviewed. Topics include: Order parameters of chiral symmetry breaking, the flavor dependence of these order parameters, speculations about the phase structure of QCD with varying number of flavors, OZI violation and its natural emergence in case of a small strange quark condensate, heavy kaon chiral perturbation theory, an update on pion-pion, pion-kaon and pion-nucleon sigma terms, the dynamics and nature of scalar mesons, the role of the scalar pion and kaon form factors, attempts to describe some strange baryons employing coupled channel dynamics tied to unitarity and chiral perturbation theory, and the role of final state interactions in Goldstone boson pair production in proton-proton collisions.

On the current status of OZI violation in πN and pp reactions

The available data on $\omega$ and $\phi$ production from $\pi N$ and $pp$ collisions are reanalyzed with respect to an OZI rule violation on the basis of transition matrix elements. The data are found to be compatible with a constant ratio $R$ up to excess energies $\epsilon{\approx}300$ MeV, however, the ratio $R$ deviates substantially from the SU(3) prediction based on the present knowledge of the $\phi-\omega$ mixing angle.

On the current status of OZI violation in πN and pp

On the current status of OZI violation in πN and pp

Probing nucleon strangeness using vector meson dominance

Calculations for N( π, e + e −) N reactions are reported to motivate measurements of the nucleon time-like form factors in the φ meson mass region. Using vector meson dominance and a field theoretical model which describes pion photoproduction data, crossing predictions for N( π, e + e −) N are detailed exhibiting dramatic, several order of magnitude enhancements from φN coupling in the nucleon form factors. These narrow, dual peaked resonances provide a novel experimental signature for OZI violation and the related strangeness content of the nucleon. A low energy analysis of the limited p( γ, φ) p data is also presented using a similar dynamic model and φN coupling.

Glueballs: Charmonium decay andp¯pannihilation

The vector glueball $O$, made of 3 valence gluons, is expected to be ``clean": it mixes less with quarkonia, but mediates OZI violations. The recent $0^{++} $ glueball candidate and the persistence of the $J/\psi, \psi' \to \rho\pi$ puzzle suggest $m_O\simeq m_{J/\psi}$, with mixing angle $\sim 2^\circ - 4^\circ$, hence $\Gamma(O\to \rho\pi$, $K^+K^-$, $e^+e^-) \sim$ MeV, few keV, few eV. Lower and upper bounds on $\Gamma_O$ can be argued from $e^+e^- \to \rho\pi$ energy scan data and the condition $B(O\to \rho\pi) > B(J/\psi\to \rho\pi)$. $O$ dominance may explain the ``large" OZI violation in $^1S_0(\bar pp)\to \phi\gamma$ vs. $\omega\gamma$.

OZI violation and polarization effects in nucleon-nucleon induced production of vector mesons

Large violations of the OZI-rule have been observed in pp-annihilation into ϕ mesons when the initial state is in triplet spin configuration. One possible explanation for this phenomenon is that this is due to a small negatively polarized ss-component in the nucleon which has been found in polarized deep inelastic scattering of leptons. In the nonperturbative region there is little experimental information on the sign of Δs. We show by spin projection conservation arguments that if the ϕ-production enhancement in the pp → ϕπ is due to the transfer of a ss from the initial nucleon to the final ϕ, then Δs must be preferentially positive. We study polarization phenomena in the process N + N → + N+ V0 where V0 is a vector meson near threshold and we show that a comparison of the pp → ppϕ reaction (which is dominated by a spin triplet in the initial state, at threshold) and the np → npϕ (which is driven by non-interfering spin triplet and spin singlet amplitudes) would test quantitatively the ss-driven spin triplet dominance. Finally we discuss the possibility of using the relationship between the Gerasimov-Drell-Hearn sum-rule and the integral of the spin structure function g1p to measure the polarization of the ss-component at low momentum transfer.

Two meson doorway calculation forpp → Øπ including off-shell effects and the OZI rule

The leading two meson doorway contributions to the reactionpp → oπ, φπ, due to K*K andpp intermediate states are calculated beyond unitarity approximation. The dependence of the results on the off-shell parametrization is explored and the effect of the finite width of the propagating mesons is estimated. The rates obtained from the rescattering mechanisms are in agreement with the data for ¯pp →φπ annihilation at rest. The vertices entering the calculation do not require any unexplained OZI violation, in particular no substantials− configuration in the nucleon appears to be needed.

Strange quark, heavy quark and gluon contents of light hadrons

The sea-quark content of baryons (such as ss , cc , bb …) is calculated by a combined use of the QCD trace anomaly and a chiral quark model. The result is applied to the examination of the explicit symmetry breaking in baryons, the intrinsic heavy quarks in baryons, and the Higgs-baryon coupling constants. We find that (i) the small ss content, large πN sigma term (∼45 MeV) and the Gell-Mann-Okubo mass formula for baryons are consistently explained contrary to the naive argument based on the lowest-order expansion by the current quark masses. The basic point is the non-linear dependence of the physical quantities on the strange quark mass. (ii) The probability of finding charm in the nucleon is about 0.5%, which is relevant to the charm structure function of the nucleon at large x B j and also to the charm production in proton-nucleus collisions at large Feynman x F. (iii) Both strange and heavy quarks are equally important for the Higgs-nucleon coupling. Small but non-negligible OZI violation in baryons due to the axial anomaly plays a key role in all the above quantities. The sea-quark content of the pion and the kaon and the color-sextet quark content in the nucleon are also discussed.

How can the strangeness content of the proton be both large and small

Experimental data suggest that some strange quark bilinear operators have relatively large matrix elements in the proton, while others are very small. We propose a likely resolution of this problem. The mixing between the light quark q q and the s s meson states strongly depends on the spin-parity of the meson multiplet. We conjeture that this pattern of OZI violation in mesons and the suppression of some strange matrix elements in the proton are caused by the same nonperturbative mechanism. We construct helicity-dependent strange quark distributions in the proton, which have the expected large x nonperturbative behavior and propose the experiments in which our hypothesis can be tested.

OZI violation in the nucleon, delta's and hyperons

The anomalous quark contents in the octet and decouplet baryons such as the s̄s content in the proton or the ūu content in the Ω − are examined on the basis of a chiral quark model, in which the constituent quark masses are given dynamically by the spontaneous breaking of the chiral symmetry. It is shown that the flavor mixing due to the U A(1)-anomaly gives rise to anomalous quark contents of all the flavors, while the short-range interaction between the constituent quarks (one-gluon exchange) tends to suppress (enhance) them for the decuplet (octet) baryons. The resulting πN sigma term is enhanced by about 20% due to one-gluon exchange.

The OZI rule in charmonium decays above D [formula omitted] threshold

A drastic change in OZI-violating transitions is predicted for charmonium as one crosses the D D threshold. A new source of OZI violation is introduced by the opening of the OZI-allowed D D channel which enables the forbidden process to occur in two OZI-allowed steps with the intermediate D D state on shell. A simple estimate using unitarity shows that the sum of the branching ratios for the OZI-forbidden final states can be the same order of magnitude as the branching ratio for the allowed D D state. It is therefore dangerous to assume that charmonium decays just above D D threshold are 100% D D , and similarly for the bottomonium decays above the B B threshold.

Glueballs, multiquark states and the OZI rule

New signatures for detection of non-quarkonium mesons are considered, including K +K + π + π − and K SK S π + π + decays for states where K +K + and K +K ∗+ decays are forbidden, and A-dependence of S ∗ and δ production on nuclei by kaon beams. Analysis of OZI rule shows that only selection rules forbidding hairpin diagrams are valid and that φφ production by pion beams is not a serious OZI violation indicating presence of glueballs.