Relativistic string model of light mesons with massless quarks

The straightline string model of mesons with massless fermions (“quarks”) at the string endpoints is constructed. The spectrum of the model, consisting of four Regge trajectories weakly non-linear atM ²～0, is obtained. A comparison of the model predictions with the experimental spectrum of light mesons and prospects for future searches are discussed.     

The nuclear Coulomb sum rule in a relativistic model

The nuclear Coulomb sum rule is investigated in a relativistic quantum field theory of the nucleus based on baryons and mesons. First an effective, local, covariant, conserved electromagnetic current operator is constructed for the many-baryon system. It describes the electromagnetic structure of an isolated nucleon; the lowest-mass two-pion contribution to the spectral weight functions of the form factors is contained in it. The sum rule is then evaluated in a model based on baryons and neutral scalar and vector mesons. In the mean-field approximation (MFT) this model correctly describes the saturation properties of nuclear matter. The “one-body” term in the sum rule can be evaluated exactly through the use of the canonical anticommutation relations for the baryon field and the identification of conserved quantities. The remaining relativistic two-body contribution is evaluated in the MFT. Meson contributions to the sum rule at large momentum transfers $\text{q}\text{2k}{}_{\mathrm{<mtext>F</mtext>}}\text{? 1}$ completely dominate anticipated static, short-range, two-nucleon correlation contributions to the non-relativistic Coulomb sum rule. One possible implication is that the nucleus must (at least) be considered as a dynamic system of mesons and baryons.     

Properties of narrowU(3.1) based on theM-diquonium 651-1651-1651-1interpretation

We study the properties ofU(3.1) assuming that theU is anM-diquoniumsq \(\bar q\) ²(q = u ord) state. It is shown that the annihilation decay which becomes the most important for usual diquonia is forbidden forU. We show there exist various reasons which makeU narrow. NearU(3.1) we expect other narrow diquonia. We also compute the electromagnetic mass splitting and find thatU ^?? is the heaviest andU ⁰ is the lightest.     

A consistent derivation of the real and imaginary parts of the heavy ion potential below and above the Coulomb barrier

In a model including approximately a large set of non-elastic channels, the real and imaginary potentials are consistently derived. The “anomaly” of the real potential which sharply increases in the vicinity of the Coulomb barrier where the imaginary potential is strongly reduced is studied in ¹⁶O + ⁴⁰Ca and ¹⁶O + ²⁰⁸Pb systems. The results on the imaginary potential are discussed and compared to our previous calculation.     

Quantum-related reference frames and the local physical significance of potentials

In a sequel to our previous paper we discuss two thought experiments which show that potentials in force-free regions have not only a nonlocal physically measurable significance (via, e.g., ∮A ·dl), but, in singly connected portions of that region, also have a necessary local significance (via their quantum spread ΔA, which cannot be neglected). We then show, in continuation to the foregoing paper, how suchA arise “geometrically” as kinematic quantities associated with the transformation between “quantum-related” reference frames, e.g., when the relative frame velocities areq-numbers possessing a quantum spread.     

Hybrids: Mixed states of quarks and gluons

We calculate the spectrum of the four ground state hybrid $\text{(}\text{q}\text{qg}\text{)}$ nonets, J^PC = (0, 1, 2)^?+, 1^??, using the MIT bag model to first order in cavity perturbation theory. Quark and gluon self-energies are included by a fit to the s-wave mesons and baryons and to the glueball candidate i(1440). We find a large gluon self-energy which substantially increases our predictions of the glueball and hybrid masses. We discuss the phenomenology of hybrids, including a suggestion that the A₃ (1670) and a second peak at 1850 MeV in the fπ channel may be mixtures of the isovector $\text{q}\text{q}$ d-wave state with the $\text{q}\text{qg}$ s-wave.     

Tests of various models for the weak decays of heavy flavour states

It is discussed how two models which were proposed to explain the lifetime difference betweenD ⁰ andD ⁺ mesons can be subjected to further tests. These two models are the “SU (4) 20-plet dominance” model and the “gluon bremstrahlung” model forW exchange. The tests can be performed by studying inclusive decays—e.g.,F ⁺ lifetime or semi-leptonic branching ratio—or special exclusive modes in the non-leptonic and semileptonic decays. It is suggested thatF ⁺ semi-leptonic decays can lead to glueball production. The decays of bottom mesons are discussed in this context, too.     

Multifractal Formalism for Almost all Self-Affine Measures

We conduct the multifractal analysis of self-affine measures for “almost all” family of affine maps. Besides partially extending Falconer’s formula of L ^q -spectrum outside the range 1 < q ≤ 2, the multifractal formalism is also partially verified.     

A steeply-rising potential in tensor gauge theory

Massive tensor gauge mesons produce a steeply rising “potential” of the type M²r² in a non-perturbative classical solution of an Einstein-like equation. Such a potential is shown to give rising Regge trajectories.     

Influence of the surface electric field in ion-beam-surface interaction at grazing incidence

We have measured the polarization of light emitted after ion surface scattering at small angle of incidence. The measurements are carried out with H⁺-, H ₂ ⁺ - and He⁺-ions under UHV-conditions with mono- and polycrystalline targets. We explain the typical variation of the polarization as “post collision Stark interaction” (PCSI) in the surface electric field, which can force transitions between nearly degenerate terms. The electric field is composed of two different contributions, a strong but short range surface field which is “seen” by atomsand ions and a long range but weak field due to the image charge which is “seen” to first orderonly by ions. The influence of the electric field on H-Balmer radiation is negligible at typical survival distances r_s≧0.35nm. But in contrast to H-atoms He⁺-ions feel the additional influence of the image field leading to a strong alteration of the polarization of the emitted light. The polarization of the Balmer-radiation stemming from Coulomb exploding H ₂ ⁺ -beams is observed to be modified by the electric field of the “spectator proton”.     

Hadron spectroscopy with covariant Coulomb and confining interactions

Using a Bethe—Salpeter approach to gluon exchange and confining h.o. interactions in q$\text{q}$ and qqq systems, an FKR-like differential equation is derived for both in a Wick-rotated four-dimensional space, yielding an exact spectrum for mesons and a very similar one for baryons. The Coulomb term exhibits a 20% effect on the low-lying energy levels and gives rise to a more consistent determination of the h.o. spring constant at the standard value 1 GeV² than otherwise.     

QCD Coulomb gauge approach to exotic hadrons

The Coulomb gauge Hamiltonian model is used to calculate masses for selected J^PC 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).     

New method of studying slow strange meson properties in nuclear matter

We suggest a new experimental method to explore the properties of slow strange mesons at normal nuclear matter density. We show that the K⁺ and K^? mesons with extremely small momenta relative to the surrounding medium rest frame can be produced in nucleus-nucleon collisions, and their production cross-sections are experimentally measurable. Experiments on the study of the momentum dependence of meson-nuclear potentials are discussed.     

Confront holographic QCD with Regge trajectories of vectors and axial-vectors

By matching the predictions of the Dp–Dq soft-wall model in type II superstring theory with the spectra of vector and axial-vector mesons, we show the dependence of the Regge trajectories parameters on the metric parameters of the model. From the experimental results of Regge parameters for vector mesons, it is found that the D3 background brane with both q=5 and q=7 probe brane and D4 background brane with q=4 probe brane are close to the realistic holographic QCD. We also discuss how to realize chiral symmetry breaking in the vacuum and asymptotic chiral symmetry restoration in high excitation states. We find that the constant component of the 5-dimension mass square of axial-vector mesons plays an efficient role to realize the chiral symmetry breaking, and a small negative z ⁴ correction in the 5-dimension mass square is helpful to realize the chiral symmetry restoration in high excitation states.     

On the particle multiplicity distributions at high energy

An experiment has been performed to study the inclusive photoproduction of π⁰ mesons. Photoproduced π⁰'s were detected in a hodoscope consisting of 14 lead glass Cerenkov counters. To obtain the cross sections at a photon energy of 6 GeV we used the photon-difference method. Data are presented in terms of the Feynman variable $\text{x = q}{}_6{}^1\text{(√s/2)}$ and the trnasverse momentum q⊥. We have measured four q⊥ distributions at x = 0.2, 0.4, 0.6 and 0.8. The results dhow that the π⁰ rate at small values of q⊥ is smaller than the π± rate. The data can be fitted smoothly by a form A exp (?Bq_⊥²) with a value about 3.5 GeV^?2 for the slope parameter B.     

Weitere Messungen zur Anisotropie der intermolekularen Wechselwirkung durch Streuung von Molekülen in definiertem Quantenzustand

The interaction between diatomic molecules and rare gas atoms can be described by the realistic, though simplified potentialV=?[(r_m/r)¹²(1 +q₁₂P₂(cosθ))?2(r_m/r)⁶(1+q₆P₂(cosθ))] The determination of the parameters?, r _m andq ₆has been treated in the two previous parts of this series. The present final paper describes the determination of the anisotropy parameter in the repulsive part of the potential, q₁₂, for the system CsF-He. Whileq ₆ could be derived using only the dependence of the total scattering cross section on the molecular rotational state, the determination ofq ₁₂ requires, in addition, knowledge of the velocity dependence. The comparison of the experimental data for CsF in the rotational states ¦J, M〉=¦1, 1〉 and ¦1, 0〉 with cross sections calculated by means of the “high energy” approximation yields the result:q ₁₂=0.9±0.2. The validity of the “high energy” approximation in the velocity range covered by the experiment is discussed.     

On the geometry and homology of certain simple stratified varieties

We study certain mild degenerations of algebraic varieties which appear in the analysis of a large class of supersymmetric theories, including superstring theory. We analyze Witten’s σ-model [Nucl. Phys. B 403 (1993) 159] and find that the non-transversality of the superpotential induces additional singularities and a stratification of the ground state variety. This stratified variety admits certain homology groups such that ⊕_qH^2q satisfies the “Kähler package” of requirements [Ann. Math. Studies 102 (1982) 303]. Also, this ⊕_qH^2q extends the “flopped” pair of small resolutions [Nucl. Phys. B 416 (1994) 414; Nucl. Phys. B 330 (1990) 49; Commun. Math. Phys. 119 (1988) 431] to an “(exo)flopped” triple, and is compatible with both mirror symmetry [S.-T. Yau (Ed.), Mirror Manifolds, International Press, Hong Kong, 1990; B. Greene, S.-T. Yau (Eds.), Mirror Manifolds II, International Press, Hong Kong, 1996] and string theory [Mod. Phys. Lett. A 12 (1997) 521; Nucl. Phys. B 451 (1995) 96] results. Finally, we revisit the conifold transition [Nucl. Phys. B 330 (1990) 49] as it applies in our formalism.     

Inelastic scattering and nucleon transfer in the system232Th+206Pb near the Coulomb barrier

Nucleon transfer accompanied by Coulomb excitation was studied in the system²⁰⁶Pb+²³²Th atE _Lab=6.4 MeV/u. Particle-particle-gamma coincidence techniques were used to identify excited states of reaction products populated through inelastic scattering and nucleon transfer reactions. The mean excitation energy was measured by means of aγ-ray energy and multiplicity filter consisting of 6 NaI detectors. Large cross sections for one-neutron and two-neutron pick-up from²³²Th are observed. The impact-parameter dependence of the neutron transfer is analyzed in terms of semiclassical barrier penetration models. Using realistic neutron potentials with a diffuse surface, the experimental data are in accordance with the assumption of a “cold” transfer to states near the yrast line.     

QQG hybrid mesons in the MIT bag model

We suggest that hybrid (q$\text{q}$g) mesons could exist with rather light masses. The spectrum of the ground state nonets, J^PC = (0, 1, 2)^?+; 1^?? is calculated in the MIT bag model including O(α_s) energy shifts. We discuss hadronic transitions among these states, consider their possible production at LEAR and SPEAR and indicate some interesting decay signatures.