Dynamical fermion mass generation by a strong Yukawa interaction

We consider a model with global Abelian chiral symmetry of two massless fermion fields interacting with a complex massive scalar field. We argue that the Schwinger-Dyson equations for the fermion and boson propagators admit ultraviolet-finite chiral-symmetry-breaking solutions provided the Yukawa couplings are large enough. The fermions acquire masses and the elementary excitations of the complex scalar field are the two real spin-zero particles with different masses. As a necessary consequence of the dynamical chiral symmetry breakdown both in the fermion and scalar sectors, one massless pseudoscalar Nambu--Goldstone boson appears in the spectrum as a collective excitation of both the fermion and the boson fields. Its effective couplings to the fermion and boson fields are calculable.Comment: 9 pages, REVTeX4, uses feynmp, 1 eps figur

Exiting the Porkway: The Transformation of Transportation Politics

Over the past two decades, there has been a decisive shift in how transportation policy is developed. For years, this policy area was viewed as one of the least combative arena in Washington. That is no longer the case. Theodore Lowi and James Q. Wilson’s views on policy arenas and political types will provide the framework for a discussion of the shift that transportation politics have undergone. Additionally, R. Douglas Arnold’s theory from “The Logic of Congressional Action” that reelection is the main force behind the votes of legislators will be used to gain an understanding of how individual legislators shifted their votes over time. A microcosm of this shift occurred in South Carolina, where there were great shifts in how legislators voted on the various policies that have been passed since 1991. This thesis will examine the legislation, and the way in which South Carolina’s Congressional Delegation voted on them. Ultimately, it will show that transportation politics were distributive politics until after the SAFETEA-LU legislation of 2005, after which they became regulatory politics. Legislators always voted with reelection in mind, but their views on what would get them reelected changed over time

Goldstone boson counting in linear sigma models with chemical potential

We analyze the effects of finite chemical potential on spontaneous breaking of internal symmetries within the class of relativistic field theories described by the linear sigma model. Special attention is paid to the emergence of ``abnormal'' Goldstone bosons with quadratic dispersion relation. We show that their presence is tightly connected to nonzero density of the Noether charges, and formulate a general counting rule. The general results are demonstrated on an SU(3)xU(1) invariant model with an SU(3)-sextet scalar field, which describes one of the color-superconducting phases of QCD.Comment: 10 pages, REVTeX4, 4 eps figures, v2: general discussion in Sec. IV expanded and improved, references added, other minor corrections throughout the tex

Spontaneous symmetry breaking in the linear sigma model at finite chemical potential: One-loop corrections

We investigate spontaneous symmetry breaking within the linear sigma model with the SU(2)xU(1) internal symmetry at finite chemical potential, which was suggested as a model for kaon condensation in the CFL phase of dense quark matter. One-loop corrections to the scalar field effective potential as well as its propagator are calculated. Particular attention is paid to the type-II Goldstone boson that appears in the Bose--Einstein condensed phase. Furthermore, we show that the type-I Goldstone boson -- the superfluid phonon -- is allowed to decay due to the nonlinearity of its dispersion relation at high momentum, and determine its decay width.Comment: 13 pages, REVTeX4, 37 eps figures; v2: substantial error in Sec. IV corrected, references added, other minor corrections; version to appear in Phys. Rev.

Interference between direct ionisation and positronium formation in continuum in positron-hydrogen collisions

The fully differential cross section for positron-impact ionisation of hydrogen is calculated in a two-centre Born approximation. It is suggested that two-centre approaches to the problem should assume incoherent combination of contributions from direct ionisation of the atom and positronium formation in continuum

Pleomorphic adenoma rehabilitative treatment in growing up patient: a 20-years follow-up

OBJECTIVE: Although tumors of minor salivary glands are rare, the pleomorphic adenoma is the most common pathology among the benign neoplasm and can be found with high prevalence in the junction between hard palate and soft palate. Most of the maxillary tumors are surgically treated through either a total or partial maxillectomy. However, surgical defects lead to both clinical and psychologic disorders for the patient. A postoperative obturator prosthesis is a good option in patients who underwent maxillectomy. It allows to restore both masticatory and speaking functions, as well as aesthetic appearance. When reconstruction of the surgical site is possible, an implant-supported prosthesis can be considered to guarantee a better function and aesthetic's rehabilitation. CASE REPORT: This clinical report presents the prosthetic rehabilitation of a patient who underwent maxillectomy because of a pleomorphic adenoma of hard palate minor salivary glands. The patient was treated with a palatal obturator prosthesis first and with an implant-supported prosthesis after surgical site's reconstruction and complete healing. CONCLUSIONS: The rehabilitation of the patient after maxillectomy through both these devices was an excellent option and provided clinical benefits, improving the patient's quality of life, allowing the patient's reinsertion into societ