The Nielsen Identities of the SM and the definition of mass

In a generic gauge theory the gauge parameter dependence of individual Green functions is controlled by the Nielsen identities, which originate from an enlarged BRST symmetry. We give a practical introduction to the Nielsen identities of the Standard Model (SM) and to their renormalization and illustrate the power of this elegant formalism in the case of the problem of the definition of mass.We prove to all orders in perturbation theory the gauge-independence of the complex pole of the propagator for all physical fields of the SM, in the most general case with mixing and CP violation. At the amplitude level, the formalism provides an intuitive and general understanding of the gauge recombinations which makes it particularly useful at higher orders. We also include in an appendix the explicit expressions for the fermionic two-point functions in a generic R_\xi gauge.Comment: 28 pages, LaTeX2e, 4 Postscript Figures, final version to appear on PRD, extensive revision

Letter processing and font information during reading: beyond distinctiveness, where vision meets design

Letter identification is a critical front end of the reading process. In general, conceptualizations of the identification process have emphasized arbitrary sets of distinctive features. However, a richer view of letter processing incorporates principles from the field of type design, including an emphasis on uniformities across letters within a font. The importance of uniformities is supported by a small body of research indicating that consistency of font increases letter identification efficiency. We review design concepts and the relevant literature, with the goal of stimulating further thinking about letter processing during reading

Irreducible Multiplets of Three-Quark Operators on the Lattice: Controlling Mixing under Renormalization

High luminosity accelerators have greatly increased the interest in semi-exclusive and exclusive reactions involving nucleons. The relevant theoretical information is contained in the nucleon wavefunction and can be parametrized by moments of the nucleon distribution amplitudes, which in turn are linked to matrix elements of three-quark operators. These can be calculated from first principles in lattice QCD. However, on the lattice the problems of operator mixing under renormalization are rather involved. In a systematic approach we investigate this issue in depth. Using the spinorial symmetry group of the hypercubic lattice we derive irreducibly transforming three-quark operators, which allow us to control the mixing pattern.Comment: 13 page

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

Domain wall in a chiral p-wave superconductor: a pathway for electrical current

Superconductors with p+ip pairing symmetry are characterized by chiral edge states, but these are difficult to detect in equilibrium since the resulting magnetic field is screened by the Meissner effect. Nonequilibrium detection is hindered by the fact that the edge excitations are unpaired Majorana fermions, which cannot transport charge near the Fermi level. Here we show that the boundary between p_x+ip_y and p_x-ip_y domains forms a one-way channel for electrical charge. We derive a product rule for the domain wall conductance, which allows to cancel the effect of a tunnel barrier between metal electrodes and superconductor and provides a unique signature of topological superconductors in the chiral p-wave symmetry class.Comment: 6 pages, 3 figure

Ethnicity and social relations in a Young Offenders Institution

The idea of ‘race relations in prison' brings together potent symbols of troubled times. The numbers of young men being confined to prison seems to reach record levels on an annual basis while concerns about social cohesion are haunted by a fear that British society no longer has a strong image of itself. Ever since the riots in Bradford, Oldham and Burnley in Spring/Summer 2001 there has been intense political concern that white and minority ethnic communities in Britain are growing apart, not together. More recently, public unease about knife and gun crime has led to calls for tougher prison sentences, alongside bewilderment at the perceived violence and nihilism among Britain's young people

Translation and Bilingualism in Monica Ali’s and Jhumpa Lahiri’s Marginalized Identities

This investigation seeks to demonstrate how Ali and Lahiri represent two different migrant experiences, Muslim and Indian, each of which functioning within a multicultural Anglo-American context. Each text is transformed into the lieu where identities become both identities-intranslation and translated identities and each text itself may be looked at as the site of preservation of native identities but also of the assimilation (or adaptation) of identity. Second-generation immigrant women writers become the interpreters of the old and new cultures, the translators of their own local cultures in a space of transition

Windows over a New Low Energy Axion

We outline some general features of possible extensions of the Standard Model that include anomalous U(1) gauge symmetries, a certain number of axions and their mixings with the CP-odd Higgs sector. As previously shown, after the mixing one of the axions becomes a physical pseudoscalar (the axi-Higgs) that can take the role of a modified QCD axion. It can be driven to be very light by the same non-perturbative effects that are held responsible for the solution of the strong CP-problem. At the same time the axi-Higgs has a sizeable gauge interaction, which is not allowed to the Peccei-Quinn axion, possibly explaining the PVLAS results. We point out that the Wess-Zumino term, typical of these models, can be both interpreted as an anomaly inflow from higher dimensional theories (second window) but also as a result of partial decoupling of an extra Higgs sector (and of a fermion) that leaves behind an effective anomalous abelian theory (first window) in a broken St\"{u}ckelberg phase. The possibility that the axi-Higgs can be heavy, of the order of the Higgs mass or larger, however, can't be excluded. The potentialities for the discovery of this particle and of anomaly effects in the neutral current sector at the LHC are briefly discussed in the context of a superstring inspired model (second window), but with results that remain valid also if any of the two possibilities is realized in Nature.Comment: 17 pages, 8 Figs, replaced with revised final version, to appear on Phys.Lett.

Pseudo Identities Based on Fingerprint Characteristics

This paper presents the integrated project TURBINE which is funded under the EU 7th research framework programme. This research is a multi-disciplinary effort on privacy enhancing technology, combining innovative developments in cryptography and fingerprint recognition. The objective of this project is to provide a breakthrough in electronic authentication for various applications in the physical world and on the Internet. On the one hand it will provide secure identity verification thanks to fingerprint recognition. On the other hand it will reliably protect the biometric data through advanced cryptography technology. In concrete terms, it will provide the assurance that (i) the data used for the authentication, generated from the fingerprint, cannot be used to restore the original fingerprint sample, (ii) the individual will be able to create different "pseudo-identities" for different applications with the same fingerprint, whilst ensuring that these different identities (and hence the related personal data) cannot be linked to each other, and (iii) the individual is enabled to revoke an biometric identifier (pseudo-identity) for a given application in case it should not be used anymore