Coupling constants and the nonrelativistic quark model with charmonium potential

Hadronic coupling constants of the vertices including charm mesons are calculated in a nonrelativistic quark model. The wave functions of the mesons which enter the corresponding overlap integrals are obtained from the charmonium picture as quark-anti-quark bound state solutions of the Schrödinger equation. The model for the vertices takes into account in a dynamical way the SU₄ breakings through different masses of quarks and different wave functions in the overlap integrals. All hadronic vertices involving scalar, pseudoscalar, vector, pseudovector and tensor mesons are calculated up to an overall normalization constant. Regularities among the couplings of mesons and their radial excitations are observed: (i) Couplings decrease with increasing order of radial excitations; (ii) in general they change sign if a particle is replaced by its next radial excitation. The k-dependence of the vertices is studied. This has potential importance in explaining the unorthodox ratios in different decay channels (e.g. $\text{D}\text{D}\text{, D}\text{D}{}^1\text{, D}{}^1\text{D}{}^1$). Having got the hadronic couplings radiative transitions are obtained with the current coupled to mesons and their recurrences. The resulting width values are smaller than those conventionally obtained in the native quark model. The whole picture is only adequate for nonrelativistic configurations, as for the members of the charmonium- or of the γ-family and most calculations have been done for transitions among charmed states. To see how far nonrelativistic concepts can be applied, couplings of light mesons are also considered.     

A mechanism for quark confinement

Euclidean field configurations carrying half integral topological charge, merons, can, unlike ordinary instantons, confine quarks at moderate coupling g. Logarithmic interactions between merons prevent isolated ones from existing for small g. However, in four dimensional QCD a crude calculation indicates a phase transition to a quark confining plasma at an effective coupling $\text{g}{}^2\text{4π}{}^2\text{≈}\text{1}\text{4}$.     

Nucleon charge form factors and chiral quark models

Calculations of the proton and neutron charge form factors G_E^p,n(q²) are presented, based on chiral bag as well as confining Dirac potential models with chiral pion-quark coupling. Special emphasis is placed on a detailed treatment of the charged pion cloud contribution to the nucleon current. The role of a finite extension of the pion-quark vertex in truncating the summation over intermediate quark bag states is studied. Quark core radii (including recoil corrections) are constrained by a simultaneous calculation of the nucleon axial form factor. The proton charge form factor is well reproduced for $\text{|q}{}^2\text{|}{}^{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{? 0.7}\text{GeV}$ with quark core rms radii between 0.5–0.6 fm. About $\text{1}\text{3}$ of the proton charge is carried by the pion cloud in this model. The neutron charge form factor is obtained with the correct sign and overall q² dependence but needs further refinements, probably at the level of the isoscalar form factor.     

Charge properties of the hadronic system in vp and νp interactions

Charge properties of the hadronic systems from νp and $\text{ν}\text{p}$ scattering in BEBC are studied in the framework of the quark-parto model (QPM). The average charges $\text{〈Q}{}_{\mathrm{<mtext>jet</mtext>}}\text{〈}{}^{\mathrm{<mtext>\nu </mtext>}}$ and $\text{〈Q}{}_{\mathrm{<mtext>jet</mtext>}}\text{〈}{}^{\mathrm{<mtext>\nu </mtext>}}$ of a quark jet and a d-qua jet, respectively, are determined according to two different methods. The difference $\text{〈Q}{}_{\mathrm{<mtext>jet</mtext>}}\text{〈}{}^{\mathrm{\nu }}\text{? 〈Q}{}_{\mathrm{<mtext>jet</mtext>}}\text{〈}{}^{\mathrm{<mtext>\nu </mtext>}}$ is in agreement with e QPM value of 1. Scaling of charge and energy flow in the angular variable λ is demonstrated. The ratios $\text{ΔQ}{}^{\mathrm{<mtext>\nu </mtext>}}\text{/ΔQ}{}^{\mathrm{\nu }}$ of charge flows in νp a $\text{ν}\text{p}$ scattering are in accord with the QPM in both hemispheres.     

KL − KS mass difference and quark models

The matrix element $\text{〈}\text{K}\text{?}{}^0\text{|H}{}_{\mathrm{<mtext>W</mtext>}}\text{|}\text{K}{}^0\text{〉}$ is calculated in the quark MIT bag model and in several relativized versions of the quark harmonic-oscillator models for hadrons. The results of the MIT bag model depend strongly on the particular choice of parameters, while the results of the harmonic-oscillator model are relatively stable on the variation of model parameters. The harmonic-oscillator model which takes into account the c.m. motion (the RHO model) is in reasonably good agreement with the vacuum-saturation value.     

Excitation of the 15.110 MeV state of 12C by neutrinos or antineutrinos

Formulae for cross sections of $\text{ν}{}^{12}\text{C(g.s.)}\text{→ ν}{}^{12}\text{C}{}^1\text{(15.110)}$ and $\text{ν}{}^{12}\text{C(g.s.)}\text{→}\text{ν}{}^{12}\text{C}{}^1\text{(15.110)}$ and for angular distributions and circular polarizations of the subsequent decay photons are derived in a model-independent (elementary-particle) approach. Our results indicate that, granting validity of the isotriplet hypothesis which relates the isovector components of the hadronic neutral weak current to the hadronic charged weak polar and axial currents, the numerical predictions of these quantities are strikingly different between solutions A and B.     

Has asymptotic freedom something to do with charmonium

We analyse the effects of logarithmic corrections due to asymptotic freedom in the potential describing short-range forces in charmonium. This allows us to show that due to the size of the effective quark-gluon coupling ($\text{α}{}_{\mathrm{<mtext>s</mtext>}}\text{(M}{}_{\mathrm{J/\Psi }}{}^2\text{) ? 0.4}$), the wave function extensions are much larger than the region of space where asymptotic freedom really has predictive power. The resulting ambiguities in the spin-dependent medium-range forces are explored. Also, such a value of α_s makes perturbative calculations of widths unreliable. We point out that the situation is not significantly improved for quark masses of 5 GeV. Indeed, below 20 GeV, short-range forces play a marginal role as compared to confinement forces.     

Broken conformal symmetry and hadronic scaling

High energy, large momentum transfer hadronic reactions are studied in the framework of broken conformal symmetry. Hadrons lie on almost linear Regge trajectories. Inclusive cross section scale as $\text{～s}{}^{\mathrm{?2}}\text{(}\text{q}{}^2{}_{\mathrm{<mtext>T</mtext>}}\text{s)}{}^{\mathrm{?4}}$. Large rates of heavy particle production are predicted.     

SU(6) × SL(3, R) color quark model

A nonrelativistic color quark model based on the spectrum generating group SU(6)×SL(3, R) is presented. The model unifies SU(6) and the Regge classification with linear L vs m² mass spectrum. Baryons are predicted to belong to the ($\text{56}\text{, L}{}^{\mathrm{P}}\text{= (}\text{even}{}^{\mathrm{+}}\text{)}\text{and}\text{(}\text{70}\text{, L}{}^{\mathrm{P}}\text{= (}\text{odd}{}^{\mathrm{?}}\text{)}$ multiplets of the SU (6) × O(3) group.     

On the suppression of flavour changing neutral processes in technicolour theories

We present, in a form of a theorem, a mechanism for the suppression of flavour changing neutral currents in theories with technicolour. This mechanism prevents purely hadronic and leptonic flavour changing neutral processes, however it allows for semileptonic processes, such as $\text{K}{}_{\mathrm{<mtext>L</mtext>}}\text{→}\text{e}\text{μ}\text{or K}\text{→ πeμ}\text{with}\text{BR}\text{?}\text{10}{}^{\mathrm{?9}}\text{? 10}{}^{\mathrm{?11}}$. Illustrative toy models are considered. as an implementation of such a mechanism.     

Jetlike nature of inclusive hadronic interactions

The dominant inclusive systems formed in the beam and target hemispheres of hadronic reactions are explored for jetlike characteristics in terms of sphericity, thrust, and energy and particle flow. We compare $\text{50}\text{GeV}\text{/c π}{}^{\mathrm{?}}\text{p and}\text{p}\text{p and}\text{100}\text{GeV}\text{/c π}{}^{\mathrm{+}}\text{p and pp}$ interactions and find substantial similarities with neutrino-induced hadronic systems and with hadronic jets in e⁺e^? annihilations. We find no strong evidence for differences in angular size between the forward and backward hadronic systems formed in hadron-hadron reactions, and the single-quark jets and the diquark jets which arise variously in lepton-lepton and lepton-hadron reactions.     

The average transverse distance between partons as measured by nucleon form factors

The values of $\text{d}\text{F}{}_1\text{(q}{}^2\text{)}\text{d}\text{q}{}^2$ at q²=0 for the neutron and the proton provide a measure of the average transverse separations squared, 〈$\text{y}{}^2$〉, between a u or d quark and the rest of the partons in a nucleon. Using the measured values of the form factors (together with parton x-distributions), we find that 〈$\text{y}{}^2\text{= 17.4}\text{GeV}{}^{\mathrm{?2}}$ for u quarks and 16.4 GeV^?2 for d quarks in a proton. We speculate that the small difference between u and d quarks is caused by “quark pairing” and discuss other possible experimental signatures of quark pairing.     

Chiral lagrangian calculation of nucleon decay modes induced by d=5 supersymmetric operators

We consider the general baryon-number violating operators which are produced by dressing the supersymmetric dimension-five operators by gaugino exchanges. We then use chiral dynamics to calculate the widths for the decay modes $\text{p}\text{→}\text{K}{}^{\mathrm{+}}\text{ν}{}_{\mathrm{d}}\text{,}\text{K}{}^0\text{e}{}_{\mathrm{d}}{}^{\mathrm{+}}\text{,}\text{and n}\text{→}\text{k}{}^0\text{ν}{}_{\mathrm{d}}$. The resulting branching ratios are rather sensitive to the precise admixture of the various baryon-number violating operators involved. In particular the decay mode $\text{p}\text{→}\text{K}{}^{\mathrm{+}}\text{ν}{}_{\mathrm{d}}$ is generally dominant in qualitative agreement with previous quark model results.     

Features of dynamically broken gauge theories

We discuss several features of dynamical symmetry breaking in gauge theories of strong, weak and electromagnetic interactions. We speculate that in some such theories the fine structure constant calculable. A possible solution of the strong P and T violation problem in QCD by dynamical symmetry breaking is indicated. Self-energy divergences are absent in such models and we compute the finite electromagnetic self-energy of a quark in QCD. The mass hierarchy problem is examined. We find models in which the fermion-gauge boson mass ratio is $\text{M}{}_{\mathrm{<mtext>F</mtext>}}{}^2\text{M}{}_{\mathrm{<mtext>B</mtext>}}{}^2\text{～}\text{exp}$ ($\text{?1}\text{g}{}^2$), where g is a gauge boson coupling, which could account for the origin of weak interactions.     

Production of very massive Higgs bosons

We compare Higgs boson production mechanisms at multi-TeV hadronic colliders. In addition to the previously investigated processes gluon + gluon → H and $\text{q}\text{q}\text{→ V}{}^1\text{→}\text{VH}\text{(}\text{V}\text{=}\text{W, Z}\text{)}$, we consider Higgs boson formation by pairs of virtual W's or Z's, a process analogous to two-photon collisions in e⁺e^? scattering. The Higgs production process $\text{W}{}^1\text{W}{}^1\text{→}\text{H}$ is dominated by longitudinal W's and is the most important mechanism for M_H > 6 M_W, if the top quark mass is about 30 GeV.     

On the harmonic oscillator and free fields in the Araki approach

It is shown that in the Hamiltonian formalism the function $\text{(}\text{1}\text{π}\text{)}{}^{\mathrm{<mtext>1</mtext><mtext>4</mtext>}}\text{e}{}^{\mathrm{?x}}{}^2$ uniquely determines the Hamiltonian of the harmonic oscillator. Using the method of Araki [1] we have constructed uniquely the Hamiltonians for the representations of the CCR, which are obtained from the Fock one through operations on test functions.     

Ultraheavy quarks and K0-K0 mixing

We consider the effect of an ultraheavy quark (mass of quark greater than mass of the W-boson) of charge $\text{2}\text{3}$ on $\text{K}{}^0\text{-}\text{K}{}^0$ mixing. The calculation is done in the effective field theory formalism and the effect of QCD renormalization is included (to one loop).     

Some properties of heavy lepton families

The simplest four-quark SU(2) ? U(1) models with an anomally-free heavy lepton sector can have two charged heavy leptons and one or two neutral leprons. Such models also explain the rise in R (the ratio of hadronic to muon pair production in e⁺e^? collisions). We study some consequences of different choices of leptonic numbers for L₁ and L₂. In particular, we derive, the leptonic decay width when several final-stae leptons are massive; the cross section for $\text{e}{}^{\mathrm{+}}\text{e}{}^{\mathrm{?}}\text{→}\text{L}{}_1\text{L}{}_2$ production; the branching ratio for $\text{e}{}^{\mathrm{+}}\text{e}{}^{\mathrm{?}}\text{→}\text{L}{}_2\text{L}{}_2\text{→}\text{e}\text{3μ+}\text{missing energy}$.