Virtual Sfermion Effects on Vector-Boson Pair Production at e^+e^- Colliders

We study the quantum effects on vector-boson pair production in e^+e^- annihilation induced by the sleptons and squarks of the minimal supersymmetric extension of the standard model (MSSM) in the one-loop approximation. We list full analytic results, and quantitatively analyze the resulting deviation from the standard-model prediction of e^+e^- -> W^+W^- for the supergravity-inspired MSSM. The latter can be rendered small throughout the whole parameter space by an appropriate choice of renormalization scheme.Comment: 11 pages (Latex), 3 figures (Postscript); MSSM parameter space restricted by imposing experimental search limits, references added; accepted for publication in Phys. Lett.

Note on CKM Matrix Renormalization

A simple inspection of the one loop quark self-energy suggests a prescription of the CKM matrix renormalization in the standard model. It leads to a CKM matrix counterterm which is gauge parameter independent and satisfies the unitarity constraint, and renormalized physical amplitudes which are gauge parameter independent and smooth in quark mass difference. We make a point that caution should be practiced when interpreting the CKM martix counterterm in terms of those of parameters in a given representation due to rephasing effects from renormalization. We show how this can be done using the degrees of freedom in the on-shell renormalization scheme.Comment: version 1: 10 pages, no figures; version 2: proofread version for Phys Rev D with minor revisions: (1) divided into 3 sections; (2) added a footnote Comment on Ref. [8] as Ref. item [13]; (3) typos fixed and minor rewordin

On-Mass-Shell Renormalization of Fermion Mixing Matrices

We consider favourable extensions of the standard model (SM) where the lepton sector contains Majorana neutrinos with vanishing left-handed mass terms, thus allowing for the see-saw mechanism to operate, and propose physical on-mass-shell (OS) renormalization conditions for the lepton mixing matrices that comply with ultraviolet finiteness, gauge-parameter independence, and (pseudo)unitarity. A crucial feature is that the texture zero in the neutrino mass matrix is preserved by renormalization, which is not automatically the case for possible generalizations of existing renormalization prescriptions for the Cabibbo-Kobayashi-Maskawa (CKM) quark mixing matrix in the SM. Our renormalization prescription also applies to the special case of the SM and leads to a physical OS definition of the renormalized CKM matrix.Comment: 18 pages (Latex), to appear in Nucl. Phys.

Gauge and Scheme Dependence of Mixing Matrix Renormalization

We revisit the issue of mixing matrix renormalization in theories that include Dirac or Majorana fermions. We show how a gauge-variant on-shell renormalized mixing matrix can be related to a manifestly gauge-independent one within a generalized ${\bar {\rm MS}}$ scheme of renormalization. This scheme-dependent relation is a consequence of the fact that in any scheme of renormalization, the gauge-dependent part of the mixing-matrix counterterm is ultra-violet safe and has a pure dispersive form. Employing the unitarity properties of the theory, we can successfully utilize the afore-mentioned scheme-dependent relation to preserve basic global or local symmetries of the bare Lagrangian through the entire process of renormalization. As an immediate application of our study, we derive the gauge-independent renormalization-group equations of mixing matrices in a minimal extension of the Standard Model with isosinglet neutrinos.Comment: 31 pages, LaTeX, uses axodraw.st

Interpretation of the NuTeV experiment

The NuTeV neutrino measurement of the Weinberg angle differs by 3 standard deviations from measurements at the Z pole. We review the status of various possibilities to explain this result, including contributions from physics outside the standard model; effects of radiative corrections; nuclear corrections to parton distributions; isospin-violating effects; and effects due to strange quarks

Current status of parton charge symmetry

We review constraints on parton charge symmetry from various experiments. Recently charge symmetry violation (CSV) has been included in a global fit to high energy data. We show that CSV compatible with all high energy data would be able to remove completely the NuTeV anomaly.PACS: 11.30.Hv Flavor Symmetries – 13.15.+g Neutrino Interactions – 13.60.Hb Total and inclusive cross-sections, including deep inelastic structure function

La Psicoterapia Dinamica basata sul Modello Dinamico-Maturativo.

Un vantaggio del Modello Dinamico-Maturativo (DMM) \ue8 che considera tre livelli distinti del funzionamento umano, ognuno dei quali pu\uf2 essere oggetto specifico di trattamenti anche diversi (Crittenden, 2008a): le distorsioni di pensieri e affetti, che possono comportare inadeguatezze del comportamento, gli aspetti relazionali (in particolare quelli familiari) e le strategie utilizzate per proteggersi dal pericolo. Le stesse tecniche di valutazione del DMM, poi, in quanto esperienze relazionali, oltre a fornire informazioni fondamentali sulla configurazione di attaccamento del paziente possono costituire una prima occasione di trattamento e di sviluppo di un\u2019alleanza terapeutica. Le innovazioni introdotte dalla teoria dell\u2019attaccamento e dal DMM risultano quindi straordinariamente utili e compatibili con una psicoterapia di tipo psicoanalitico, per cui oggi si pu\uf2 parlare di una \u201cPsicoterapia Dinamica basata sul DMM\u201d (DMM based Dynamic Psychotherapy o DMM-DP) (Baldoni, 2011)