Hans-Christian Pauli

Quantum chromodynamics and other field theories on the light cone

Abstract In recent years light-cone quantization of quantum field theory has emerged as a promising method for solving problems in the strong coupling regime. The approach has a number of unique features that make it particularly appealing, most notably, the ground state of the free theory is also a ground state of the full theory. We discuss the light-cone quantization of gauge theories from two perspectives: as a calculational tool for representing hadrons as QCD bound states of relativistic quarks and gluons, and also as a novel method for simulating quantum field theory on a computer. The light-cone Fock state expansion of wavefunctions provides a precise definition of the parton model and a general calculus for hadronic matrix elements. We present several new applications of light-cone Fock methods, including calculations of exclusive weak decays of heavy hadrons, and intrinsic heavy-quark contributions to structure functions. A general non-perturbative method for numerically solving quantum field theories, “discretized light-cone quantization”, is outlined and applied to several gauge theories. This method is invariant under the large class of light-cone Lorentz transformations, and it can be formulated such that ultraviolet regularization is independent of the momentum space discretization. Both the bound-state spectrum and the corresponding relativistic light-cone wavefunctions can be obtained by matrix diagonalization and related techniques. We also discuss the construction of the light-cone Fock basis, the structure of the light-cone vacuum, and outline the renormalization techniques required for solving gauge theories within the Hamiltonian formalism on the light cone.

On the dynamics of fission: The role of reflection asymmetry in the nuclear shape

Abstract For nuclei in the actinide region we calculate within the cranking model the tensor of effective mass which has six independent components for three shape degrees of freedom — among them is the reflection asymmetry. With these mass parameters and the Strutinsky deformation energy the lifetimes for spontaneous fission are calculated in WKB approximation. The theory does not contain ad hoc parameters. Asymmetric fission is favoured; the most probable mass division (peak-to-peak ratio) agrees with the experimental data. The lifetimes for spontaneous fission from the ground state agree with the experimental data by order of magnitude. We also reproduce the experimental lifetime for isomer fission and obtain a slower de-excitation of the isomer through the first well. The results give support to the interpretation of the fission isomers as shape isomers and the validity of the adiabatic assumption.

On confinement in a light-cone Hamiltonian for QCD

Abstract. The canonical front form Hamiltonian for non-Abelian SU(N) gauge theory in 3+1 dimensions and in the light-cone gauge is mapped non-perturbatively on an effective Hamiltonian which acts only in the Fock space of a quark and an antiquark. Emphasis is put on the many-body aspects of gauge field theory, and it is shown explicitly how the higher Fock-space amplitudes can be retrieved self-consistently from solutions in the

Splitting of the pi-rho spectrum in a renormalized light-cone QCD-inspired model

q\bar q

Universal description of S-wave meson spectra in a renormalized light-cone QCD-inspired model

-space. The approach is based on the novel method of iterated resolvents and on discretized light-cone quantization driven to the continuum limit. It is free of the usual perturbative Tamm-Dancoff truncations in particle number and coupling constant and respects all symmetries of the Lagrangian including covariance and gauge invariance. Approximations are done to the non-truncated formalism. Together with vertex as opposed to Fock-space regularization, the method allows to apply the renormalization programme non-perturbatively to a Hamiltonian. The conventional QCD scale is found arising from regulating the transversal momenta. It conspires with additional mass scales to produce possibly confinement.

Renormalization of an effective light-cone QCD-inspired theory for the pion and other mesons

We show that the splitting between the light pseudoscalar and vector meson states is due to the strong short-range attraction in the

A compendium of light-cone quantization

{}^{1}{S}_{0}

Phase factors in bases for solutions of time-dependent schrödinger equations

sector which makes the pion and the kaon light particles. We use a light-cone QCD-inspired model of the mass squared operator with harmonic confinement and a Dirac-delta interaction. We apply a renormalization method to define the model, in which the pseudoscalar ground state mass fixes the renormalized strength of the Dirac-delta interaction.

On the effective light-cone QCD-Hamiltonian: Application to the pion and other mesons

A light-cone QCD-inspired model, with the mass squared operator consisting of a harmonic oscillator potential as confinement and a Dirac delta interaction, is used to study S-wave meson spectra. The two parameters of the harmonic potential and quark masses are fixed by the masses of

Succesful renormalization of a QCD-inspired Hamiltonian

\ensuremath{\rho}(770),