Non perturbative Adler-Bardeen Theorem

The Adler-Bardeen theorem has been proved only as a statement valid at all orders in perturbation theory, without any control on the convergence of the series. In this paper we prove a nonperturbative version of the Adler-Bardeen theorem in $d=2$ by using recently developed technical tools in the theory of Grassmann integration.Comment: 28 pages, 14 figure

Föderalismus ohne Insolvenz?

Die bestehenden Kreditbegrenzungen der öffentlichen Haushalte haben sich in der Vergangenheit als nicht wirksam erwiesen. Eine Reihe von Bundesländern kann mittelfristig die Finanzprobleme nicht mehr aus eigener Kraft lösen. Drei Länder klagen derzeit vor dem Bundesverfassungsgericht auf bundesstaatliche Hilfe. Wie kann eine übermäßige Verschuldung der Bundesländer verhindert werden? --

On renormalizability of the massless Thirring model

We discuss the renormalizability of the massless Thirring model in terms of the causal fermion Green functions and correlation functions of left-right fermion densities. We obtain the most general expressions for the causal two-point Green function and correlation function of left-right fermion densities with dynamical dimensions of fermion fields, parameterised by two parameters. The region of variation of these parameters is constrained by the positive definiteness of the norms of the wave functions of the states related to components of the fermion vector current. We show that the dynamical dimensions of fermion fields calculated for causal Green functions and correlation functions of left-right fermion densities can be made equal. This implies the renormalizability of the massless Thirring model in the sense that the ultra-violet cut-off dependence, appearing in the causal fermion Green functions and correlation functions of left-right fermion densities, can be removed by renormalization of the wave function of the massless Thirring fermion fields only.Comment: 17 pages, Latex, the contribution of fermions with opposite chirality is added,the parameterisation of fermion determinant by two parameters is confirmed,it is shown that dynamical dimensions of fermion fields calculated from different correlation functions can be made equal.This allows to remove the dependence on the ultra-violet cut-off by the renormalization of the wave function of Thirring fermion fields onl

Equivalent bosonic theory for the massive Thirring model with non-local interaction

We study, through path-integral methods, an extension of the massive Thirring model in which the interaction between currents is non-local. By examining the mass-expansion of the partition function we show that this non-local massive Thirring model is equivalent to a certain non-local extension of the sine-Gordon theory. Thus, we establish a non-local generalization of the famous Coleman's equivalence. We also discuss some possible applications of this result in the context of one-dimensional strongly correlated systems and finite-size Quantum Field Theories.Comment: 15 pages, latex, no figure

Quantum Electrodynamics in Two-Dimensions at Finite Temperature. Thermofield Bosonization Approach

The Schwinger model at finite temperature is analyzed using the Thermofield Dynamics formalism. The operator solution due to Lowenstein and Swieca is generalized to the case of finite temperature within the thermofield bosonization approach. The general properties of the statistical-mechanical ensemble averages of observables in the Hilbert subspace of gauge invariant thermal states are discussed. The bare charge and chirality of the Fermi thermofields are screened, giving rise to an infinite number of mutually orthogonal thermal ground states. One consequence of the bare charge and chirality selection rule at finite temperature is that there are innumerably many thermal vacuum states with the same total charge and chirality of the doubled system. The fermion charge and chirality selection rules at finite temperature turn out to imply the existence of a family of thermal theta vacua states parametrized with the same number of parameters as in zero temperature case. We compute the thermal theta-vacuum expectation value of the mass operator and show that the analytic expression of the chiral condensate for any temperature is easily obtained within this approach, as well as, the corresponding high-temperature behavior

Smooth Bosonization as a Quantum Canonical Transformation

We consider a 1+1 dimensional field theory which contains both a complex fermion field and a real scalar field. We then construct a unitary operator that, by a similarity transformation, gives a continuum of equivalent theories which smoothly interpolate between the massive Thirring model and the sine-Gordon model. This provides an implementation of smooth bosonization proposed by Damgaard et al. as well as an example of a quantum canonical transformation for a quantum field theory.Comment: 20 pages, revte

Commission des Communautes Europeennes: Groupe du Porte-Parole. Reunion de la Commission du mercredi 29 octobre 1980 = Commission of European Communities: Spokesman Group. Meeting of the Commission on Wednesday, 29 October 1980. Spokesman Service Note to National Offices Bio No. (80) 432, 30 October 1980

We study strong-field ionization and rescattering beyond the long-wavelength limit of the dipole approximation with elliptically polarized mid-IR laser pulses. Full three-dimensional photoelectron momentum distributions (PMDs) measured with velocity map imaging and tomographic reconstruction revealed an unexpected sharp ridge structure in the polarization plane (2018 Phys. Rev. A 97 013404). This thin line-shaped ridge structure for low-energy photoelectrons is correlated with the ellipticity-dependent asymmetry of the PMD along the beam propagation direction. The peak of the projection of the PMD onto the beam propagation axis is shifted from negative to positive values when the sharp ridge fades away with increasing ellipticity. With classical trajectory Monte Carlo simulations and analytical analysis, we study the underlying physics of this feature. The underlying physics is based on the interplay between the lateral drift of the ionized electron, the laser magnetic field induced drift in the laser propagation direction, and Coulomb focusing. To apply our observations to emerging techniques relying on strong-field ionization processes, including time-resolved holography and molecular imaging, we present a detailed classical trajectory-based analysis of our observations. The analysis leads to the explanation of the fine structure of the ridge and its non-dipole behavior upon rescattering while introducing restrictions on the ellipticity. These restrictions as well as the ionization and recollision phases provide additional observables to gain information on the timing of the ionization and recollision process and non-dipole properties of the ionization process.ISSN:1361-6455ISSN:0368-3508ISSN:0953-4075ISSN:0022-370

Postoperative irradiation for squamous cell carcinoma of head and neck: Retrospective comparison of accelerated radiochemotherapy and standard radiotherapy

Background: Comparison of accelerated radiochemotherapy (aRCT) and standard radiotherapy (sRT) in postoperative treatment after macroscopically complete resection of squamous cell cancers of head and neck. Material and Methods: 229 patients treated within the same period had either (no randomization) postoperative radiotherapy with conventional fractionation (60-70 Gy, 2.0 Gy per day) or received 2 fractions of 2.1 Gy per day, 8 times\textbackslash{}week, up to a total dose of 56.7 Gy with a treatment split after 2 weeks and simultaneous low dose cisplatin or carboplatin on treatment clays (cumulative dose >66 mg/m(2) or 550 mg/m(2) in 83% of patients). Results: 65 patients completed their course of twice-daily irradiations within a maximum of 35 days and therefore had aRCT; their 3-year locoregional tumor control (Kaplan-Meier estimate) was 86%, whereas that of 42 patients with prolonged twice-daily radiochemotherapy was 65% (p=0.0509). After sRT, i.e. 1 fraction daily and treatment time up to 45 days, locoregional tumor control was 67%, this result being significantly inferior to that after aRCT (p=0.0282). In multivariate analysis, pN stage, tumor site oral cavity/floor of mouth, high/moderate differentiation of squamous cell carcinoma and conventional surgery (versus CO2-laser surgery) were significantly predictive of locoregional failure. Whereas nodal status, the strongest prognostic factor, was evenly distributed among aRCT and sRT patients, there was a misbalance of 3 risk factors favoring the aRCT collective. Superior tumor control after aRCT was confirmed unilaterally for nearly each subgroup (significant for recurrent tumors, close margins, pN1/2a-b). For pN2c/pN3 nodal stage, the results after aRCT were by tendency worse than after sRT, possibly due to a particularly long interval between surgery and start of radio(chemo)therapy for the patients with aRCT (mean 58.0 days vs. 43.8 days, p=0.037). Among the total of patients the 3-year hazard for late toxicity Ill-IV was 31% after twice-daily treatment and 17% after conventionally fractionated radiotherapy (p=0.083). Conclusions:This retrospective analysis provides some evidence that accelerated radiotherapy with simultaneous chemotherapy is more potent than standard radiotherapy. However, as multivariate analysis misses significance and the influence of misbalance of some prognostic factors among aRCT and sRT patients remains unclear, only a randomized trial with stratification according to risk factors as well as a defined interval between surgery and initiation of RT can provide more evidence

String-localized Quantum Fields and Modular Localization

We study free, covariant, quantum (Bose) fields that are associated with irreducible representations of the Poincar\'e group and localized in semi-infinite strings extending to spacelike infinity. Among these are fields that generate the irreducible representations of mass zero and infinite spin that are known to be incompatible with point-like localized fields. For the massive representation and the massless representations of finite helicity, all string-localized free fields can be written as an integral, along the string, of point-localized tensor or spinor fields. As a special case we discuss the string-localized vector fields associated with the point-like electromagnetic field and their relation to the axial gauge condition in the usual setting.Comment: minor correction