11 research outputs found
Anomalous U(1)'s, Chern-Simons couplings and the Standard Model
This proceeding is based on hep-th/0605225 and it shows that the most general
anomaly related effective action contains Stuckelberg, axionic and
Chern-Simons-like couplings. Such couplings are generically non-trivial in
orientifold string vacua. A similar analysis in quantum field theories provides
similar couplings. These Chern-Simons couplings generate new signals which
might be visible at LHC.Comment: 9 pages, 2 eps figures, LaTeX, feynmf & youngtab packages. (v2:
references added). Contribution to the proceedings of the RTN project
"Constituents, Fundamental Forces and Symmetries of the Universe" conference
in Naples, October 9 - 13, 2006 and the PRIN meeting in Alessandria, December
15-16, 200
Crystal structure on rigged configurations
Rigged configurations are combinatorial objects originating from the Bethe
Ansatz, that label highest weight crystal elements. In this paper a new
unrestricted set of rigged configurations is introduced for types ADE by
constructing a crystal structure on the set of rigged configurations. In type A
an explicit characterization of unrestricted rigged configurations is provided
which leads to a new fermionic formula for unrestricted Kostka polynomials or
q-supernomial coefficients. The affine crystal structure for type A is obtained
as well.Comment: 20 pages, 1 figure, axodraw and youngtab style file necessar
Dinamica del gruppo di rinormalizzazione dei modelli di Potts gerarchici
Oggetto di questa tesi è il comportamento analitico delle funzioni termodinamiche di sistemi particolari, denominati modelli gerarchici.
Si tratta di modelli di Potts su reticoli che sono invarianti per una opportuna procedura di coarse-graining. Questa proprietà permette il calcolo esatto del gruppo di rinormalizzazione, dal quale si può ottenere una descrizione dei domini di analiticità delle funzioni termodinamiche dei sistemi ad essi associati. Tale descrizione è legata alla dinamica delle iterazioni di una opportuna mappa razionale in più variabili complesse che esprime l'operatore di rinormalizzazione associato al modello.
Si tratta di un argomento di ricerca estremamente nuovo e molti dei risultati ottenuti sono originali. All'esposizione dei risultati generali rigorosi si abbina inoltre una parte esemplificativa anche numerica, con il doppio fine di chiarire la trattazione e di esplicitare la sua generalità
Anomalies, Anomalous U(1)'s and generalized Chern-Simons terms
A detailed analysis of anomalous U(1)'s and their effective couplings is
performed both in field theory and string theory. It is motivated by the
possible relevance of such couplings in particle physics, as well as a
potential signal distinguishing string theory from other UV options. The most
general anomaly related effective action is analyzed and parameterized. It
contains Stuckelberg, axionic and Chern-Simons-like couplings. It is shown that
such couplings are generically non-trivial in orientifold string vacua and are
not in general fixed by anomalies. A similar analysis in quantum field theories
provides similar couplings. The trilinear gauge boson couplings are also
calculated and their phenomenological relevance is advocated. We do not find
qualitative differences between string and field theory in this sector.Comment: 52 pages, 2 eps figures, LaTeX, feynmf & youngtab packages (v2 -
Minor corrections, references added
The collective quantization of three-flavored Skyrmions revisited
A self-consistent large approach is developed for the collective
quantization of SU(3) flavor hedgehog solitons, such as the Skyrmion. The key
to this analysis is the determination of all of the zero modes associated with
small fluctuations around the hedgehog. These are used in the conventional way
to construct collective coordinates. This approach differs from previous work
in that it does not implicitly assume that each static zero mode is associated
with a dynamical zero mode. It is demonstrated explicitly in the context of the
Skyrmion that there are fewer dynamical zero modes than static ones due to the
Witten-Wess-Zumino term in the action. Group-theoretic methods are employed to
identify the physical states resulting from canonical quantization of the
collectively rotating soliton. The collective states fall into representations
of SU(3) flavor labeled by and are given by
where is the spin of the collective state. States with
strangeness do not arise as collective states from this procedure; thus
the (pentaquark) resonance does not arise as a collective
excitation in models of this type.Comment: 12 pages; uses package "youngtab
Systematic construction of basis invariants in the 2HDM
A new systematic method for the explicit construction of (basis-)invariants
is introduced and employed to construct the full ring of basis invariants of
the Two-Higgs-Doublet-Model (2HDM) scalar sector. Co- and invariant quantities
are obtained by the use of hermitian projection operators. These projection
operators are constructed from Young tableaux via birdtrack diagrams and they
are used in two steps. First, to extract basis-covariant quantities, and
second, to combine the covariants in order to obtain the actual basis
invariants. The Hilbert series and Plethystic logarithm are used to find the
number and structure of the complete set of generating invariants as well as
their interrelations (syzygies). Having full control over the complete ring of
(CP-even and CP-odd) basis invariants, we give a new and simple proof of the
necessary and sufficient conditions for explicit CP conservation in the 2HDM,
confirming earlier results by Gunion and Haber. The method generalizes to other
models, with the only foreseeable limitation being computing power.Comment: 19+11 pages; Young tableaux, birdtracks, syzygies, color; v2: version
published in JHE
SIMULATION NUMERIQUE DE LA CUISSON ET DE L'USINAGE DE MATERIAUX COMPOSITES
The thesis aims to simulate composite molds manufacturing, by curing of prepregs used for LCM processes. We also present solutions for predicting the effects of machining. Numerical simulation of curing involves solving thermo-mechanical problems, together with a representation of the thermo-physico chemical cross-linking reaction of the resin. A macroscopic weakly coupled thermo-physico mechanical approach is employed in the threedimensional numerical model, which is validated by numerical/experimental comparison on the angular variation of L-shaped part, from two kinds of composite materials: T300/914 and Hextool. The second part of the work deals with the simulation of composite materials machining. Numerical simulation of the machining is based on modeling of material removal process and internal stresses redistribution. The machining is modelled as a thermomechanical problem using a hybrid model. The mechanisms involved in machining are converted into equivalent thermo-mechanical loadings which are determined experimentally, and then applied to the finished surface of the workpiece. The simulation led to thecalculation of the corresponding distortions. The machining simulation requires precise knowledge of the residual stresses and the deformed shape induced by curing process. The simulated residual distortions are faced to experimental measurements after machining. The simulations are performed using the Sysply® finite element software, issued by ESI-GROUP.La thèse a pour but de simuler la fabrication des moules en matériaux composites, par cuisson de plis pré-imprégnés, utilisés pour les procédés LCM. Nous présentons également des solutions pour prédire les effets de leur usinage. La simulation numérique de la cuisson fait appel à la résolution de problèmes thermomécaniques, et également à une représentation thermo-physico chimique de la réaction de réticulation de la résine. Une approche macro thermo-physico mécanique couplée faiblement est employée dans le modèle numérique tridimensionnel, validé en le confrontant à une étude expérimentale, au niveau de la variation angulaire d'une pièce en forme de L, pour deux matériaux composites de type différent : T300/914 et Hextool. La seconde partie du travail concerne la simulation de l’usinage des matériaux composites. La simulation numérique de l’usinage s’appuie sur la modélisation de l’enlèvement de matière et de la redistribution des contraintes internes. L’usinage estmodélisé comme un problème thermomécanique en utilisant un modèle hybride. Les mécanismes associés à l’usinage sont convertis en chargements thermomécaniques équivalents qui sont déterminés expérimentalement et ensuite appliqués à la surface de la pièce usinée. La simulation conduit au calcul des distorsions induites correspondantes. La simulation de l’usinage nécessite de connaître précisément les contraintes et déformées résiduelles induites par la phase de cuisson. Les distorsions résiduelles simulées par ce modèle sont confrontées à l’expérience. Les simulations sont réalisées avec le logiciel de calcul par éléments finis Sysply®, commercialisé par ESI-GROUP