Renormalization of an effective Light-Cone QCD-inspired theory for the Pion and other Mesons

The renormalization of the effective QCD-Hamiltonian theory for the quark-antiquark channel is performed in terms of a renormalized or fixed-point Hamiltonian that leads to subtracted dynamical equations. The fixed point-Hamiltonian brings the renormalization conditions as well as the counterterms that render the theory finite. The approach is renormalization group invariant. The parameters of the renormalized effective QCD-Hamiltonian comes from the pion mass and radius, for a given constituent quark mass. The 1s and excited 2s states of $\bar u q$ are calculated as a function of the mass of the quark $q$ being s, c or b, and compared to the experimental values.Comment: 39 pages, 10 figure

Tube Model for Light-Front QCD

We propose the tube model as a first step in solving the bound state problem in light-front QCD. In this approach we neglect transverse variations of the fields, producing a model with 1+1 dimensional dynamics. We then solve the two, three, and four particle sectors of the model for the case of pure glue SU(3). We study convergence to the continuum limit and various properties of the spectrum.Comment: 29 page

Effect of Zero Modes on the Bound-State Spectrum in Light-Cone Quantisation

We study the role of bosonic zero modes in light-cone quantisation on the invariant mass spectrum for the simplified setting of two-dimensional SU(2) Yang-Mills theory coupled to massive scalar adjoint matter. Specifically, we use discretised light-cone quantisation where the momentum modes become discrete. Two types of zero momentum mode appear -- constrained and dynamical zero modes. In fact only the latter type of modes turn out to mix with the Fock vacuum. Omission of the constrained modes leads to the dynamical zero modes being controlled by an infinite square-well potential. We find that taking into account the wavefunctions for these modes in the computation of the full bound state spectrum of the two dimensional theory leads to 21% shifts in the masses of the lowest lying states.Comment: LaTeX with 5 postscript file

Quantum Macrostates, Equivalence of Ensembles and an H-Theorem

Before the thermodynamic limit, macroscopic averages need not commute for a quantum system. As a consequence, aspects of macroscopic fluctuations or of constrained equilibrium require a careful analysis, when dealing with several observables. We propose an implementation of ideas that go back to John von Neumann's writing about the macroscopic measurement. We apply our scheme to the relation between macroscopic autonomy and an H-theorem, and to the problem of equivalence of ensembles. In particular, we show how the latter is related to the asymptotic equipartition theorem. The main point of departure is an expression of a law of large numbers for a sequence of states that start to concentrate, as the size of the system gets larger, on the macroscopic values for the different macroscopic observables. Deviations from that law are governed by the entropy.Comment: 16 pages; v1 -> v2: Sec. 3 slightly rewritten, 2 references adde

Trends in diabetes prevalence, awareness, treatment, and control in French-speaking Switzerland.

Diabetes is increasing in Switzerland, but whether its management has improved is unknown. We aimed to assess diabetes prevalence, diagnosis, treatment, and control in French-speaking Switzerland. Our study used cross-sectional data for years 2005-2019 from a population-based study in Geneva, Switzerland. Overall prevalence (self-reported diagnosis and/or fasting plasma glucose level ≥ 7 mmol/L), diagnosed, treated (among diagnosed participants) and controlled diabetes (defined as a fasting plasma glucose FPG < 6.7 mmol/L among treated participants) were calculated for periods 2005-9, 2010-4 and 2015-9. Data from 12,348 participants (mean age ± standard deviation: 48.6 ± 13.5 years, 51.7% women) was used. Between 2005-9 and 2015-9, overall prevalence and frequency of diagnosed diabetes decreased (from 8.7 to 6.2% and from 7.0 to 5.2%, respectively). Among participants diagnosed with diabetes, treatment and control rates did not change from 44.1 to 51.9%, p = 0.251 and from 30.2 to 34.0%, p = 0.830, respectively. A trend towards higher treatment of participants with diabetes was found after multivariable adjustment, while no changes were found for overall prevalence, diagnosis, nor control. Among antidiabetic drugs, percentage of combinations increased from 12 to 23%; percentage of sulfonylureas and biguanides decreased from 15 to 6% and from 63 to 54%, respectively, while no trend was found for insulin. After multivariable analysis, women with diabetes were less likely to be treated but more likely to be controlled, the opposite association being found for obesity. In conclusion, in Canton Geneva, antidiabetic combination therapy is gaining importance, but only half of participants diagnosed with diabetes are treated, and glycaemic control remains poor

Compactification in the Lightlike Limit

We study field theories in the limit that a compactified dimension becomes lightlike. In almost all cases the amplitudes at each order of perturbation theory diverge in the limit, due to strong interactions among the longitudinal zero modes. The lightlike limit generally exists nonperturbatively, but is more complicated than might have been assumed. Some implications for the matrix theory conjecture are discussed.Comment: 13 pages, 3 epsf figures. References and brief comments added. Nonexistent divergent graph in 0+- model delete

Convergence of Discretized Light Cone Quantization in the small mass limit

I discuss the slow convergence of Discretized Light Cone Quantization (DLCQ) in the small mass limit and suggest a solution.Comment: 8 pages, 5 Postscript figures, uses boxedeps.te

Spontaneous symmetry breaking of (1+1)-dimensional ϕ4\bf \phi^4 theory in light-front field theory (III)

We investigate (1+1)-dimensional $\phi^4$ field theory in the symmetric and broken phases using discrete light-front quantization. We calculate the perturbative solution of the zero-mode constraint equation for both the symmetric and broken phases and show that standard renormalization of the theory yields finite results. We study the perturbative zero-mode contribution to two diagrams and show that the light-front formulation gives the same result as the equal-time formulation. In the broken phase of the theory, we obtain the nonperturbative solutions of the constraint equation and confirm our previous speculation that the critical coupling is logarithmically divergent. We discuss the renormalization of this divergence but are not able to find a satisfactory nonperturbative technique. Finally we investigate properties that are insensitive to this divergence, calculate the critical exponent of the theory, and find agreement with mean field theory as expected.Comment: 21 pages; OHSTPY-HEP-TH-94-014 and DOE/ER/01545-6

Quantum state tomography using a single apparatus

The density matrix of a two-level system (spin, atom) is usually determined by measuring the three non-commuting components of the Pauli vector. This density matrix can also be obtained via the measurement data of two commuting variables, using a single apparatus. This is done by coupling the two-level system to a mode of radiation field, where the atom-field interaction is described with the Jaynes--Cummings model. The mode starts its evolution from a known coherent state. The unknown initial state of the atom is found by measuring two commuting observables: the population difference of the atom and the photon number of the field. We discuss the advantages of this setup and its possible applications.Comment: 7 pages, 8 figure, Phys. Rev.

Klein-Gordon Equation in Hydrodynamical Form

We follow and modify the Feshbach-Villars formalism by separating the Klein-Gordon equation into two coupled time-dependent Schroedinger equations for particle and antiparticle wave function components with positive probability densities. We find that the equation of motion for the probability densities is in the form of relativistic hydrodynamics where various forces have their classical counterparts, with the additional element of the quantum stress tensor that depends on the derivatives of the amplitude of the wave function. We derive the equation of motion for the Wigner function and we find that its approximate classical weak-field limit coincides with the equation of motion for the distribution function in the collisionless kinetic theory.Comment: 13 page