A Mass-Conserving Algorithm for Dynamical Lubrication Problems With Cavitation

A numerical algorithm for fully dynamical lubrication problems based on the Elrod-Adams formulation of the Reynolds equation with mass-conserving boundary conditions is described. A simple but effective relaxation scheme is used to update the solution maintaining the complementarity conditions on the variables that represent the pressure and fluid fraction. The equations of motion are discretized in time using Newmark`s scheme, and the dynamical variables are updated within the same relaxation process just mentioned. The good behavior of the proposed algorithm is illustrated in two examples: an oscillatory squeeze flow (for which the exact solution is available) and a dynamically loaded journal bearing. This article is accompanied by the ready-to-compile source code with the implementation of the proposed algorithm. [DOI: 10.1115/1.3142903]

A dynamical mechanism to explain the top-bottom quark mass hierarchy

We discuss the mass splitting between the the top and bottom quarks in a technicolor scenario. The model proposed here contains a left-right electroweak gauge group. An extended technicolor group and mirror fermions are introduced. The top-bottom quark mass splitting turns out to be intimately connected to the breaking of the left-right gauge symmetry. Weak isospin violation occurs within the experimental limits.

Chiral symmetry breaking in QCD-like gauge theories with a confining propagator and dynamical gauge boson mass generation

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Modeling the gluon propagator in Landau gauge: Lattice estimates of pole masses and dimension-two condensates

We present an analytic description of numerical results for the Landau-gauge SU(2) gluon propagator D(p(2)), obtained from lattice simulations (in the scaling region) for the largest lattice sizes to date, in d = 2, 3 and 4 space-time dimensions. Fits to the gluon data in 3d and in 4d show very good agreement with the tree-level prediction of the refined Gribov-Zwanziger (RGZ) framework, supporting a massive behavior for D(p(2)) in the infrared limit. In particular, we investigate the propagator's pole structure and provide estimates of the dynamical mass scales that can be associated with dimension-two condensates in the theory. In the 2d case, fitting the data requires a noninteger power of the momentum p in the numerator of the expression for D(p(2)). In this case, an infinite-volume-limit extrapolation gives D(0) = 0. Our analysis suggests that this result is related to a particular symmetry in the complex-pole structure of the propagator and not to purely imaginary poles, as would be expected in the original Gribov-Zwanziger scenario.

Dynamical properties and mass-luminosity relation of elliptical galaxies

In questo elaborato abbiamo analizzato un campione di 22 galssie early-type. Utilizzando una tecnica di cross-correlazione, abbiamo ottenuto profili radiali di rotazione e di dis- persione di velocitá. Questi dati ci hanno permesso di investigare molte delle proprietá dinamiche delle nostre galassie. Abbiamo ottenuto indizi sull’anisotropia orbitale e stimato le masse e il rapporto M/L del campione. Le masse misurate variano da 1010 a 1012 M , mentre i valori degli M/L, per cui abbiamo trovato una dipendenza del tipo Log M/L ∝ 0.28 Log L , sono dell’ordine dell’unitá. Abbiamo anche riprodotto le famose relazioni di scala e abbi- amo utlizzato un set di dati sugli indici di Lick/IDS per ricercare relazioni tra le proprietá chimiche e quelle dinamiche. In particolare, abbiamo riscontrato una correlazione tra molti degli indici dipendenti dalla metallicitá e la profonditá della buca di potenziale. Tali indici sembrano correlare anche con il M/L. La rotazione e la forma del profilo di dispersione di velocitá sembrano essere ininfluenti sulle proprietá chimiche. In ultima analisi, abbiamo considerato le implicazioni delle nostre misure riguardo la natura della popolazione stellare e dell’emissione X delle nostre galassie. L’indice di colore e il M/L sembrano indicare che la popolazione stellare delle nostre galassie é dominata da stelle appartenenti alle classi spettrali late-G e early-K. Sembra inoltre esserci una correlazione tra l’emissione X degli elementi del nostro campione e la profonditá della loro buca di potenziale.

The gas mass fraction and the dynamical state in x-ray luminous clusters of galaxies at low redshift

Gli ammassi di galassie sono le strutture gravitazionalmente legate con le più profonde buche di potenziale, pertanto è previsto che questi contengano una frazione di barioni non molto diversa da quella cosmologica. Con l’introduzione di modelli sempre più accurati di fisica barionica all’interno di simulazioni idrodinamiche è stato possibile predire la percentuale cosmica di barioni presente negli ammassi di galassie. Unendo questi modelli previsionali con misure della frazione di gas in ammassi e informazioni sulla densità di barioni dell’Universo si può ottenere una stima della densità di materia cosmica Ωm. L'obiettivo di questo lavoro di Tesi è la stima di Ωm a partire dalla frazione di gas osservata in questi sistemi. Questo lavoro era stato già fatto in precedenza, ma tenendo in considerazione solo gli ammassi più massivi e dinamicamente rilassati. Usando parametri che caratterizzano la morfologia della distribuzione di brillanza superficiale nei raggi X, abbiamo classificato i nostri oggetti come rilassati o disturbati, laddove presentassero evidenze di recenti attività di interazione. Abbiamo dunque valutato l’impatto degli oggetti disturbati sulla stima del parametro cosmologico Ωm, computando il Chi2 tra la frazione di massa barionica nell’Universo e quella da noi ricavata. Infine abbiamo investigato una relazione tra il valore della frazione di gas degli ammassi rilassati e quello dei disturbati, in modo da correggere quindi questi ultimi, riportandoli nei dintorni del valore medio per i rilassati e usarli per ampliare il campione e porre un vincolo più stringente su Ωm. Anche con il limitato campione a nostra disposizione, è stato possibile porre un vincolo più stretto su Ωm, utilizzando un maggior numero di oggetti e riducendo così l’errore statistico.

Gluon-field contribution in QCD sum rules for the magnetic moments of the nucleons

The Wilson coefficient corresponding to the gluon-field strength GμνGμν is evaluated for the nucleon current correlation function in the presence of a static external electromagnetic field, using a regulator mass Λ to separate the high-momentum part of the Feynman diagrams. The magnetic-moment sum rules are analyzed by two different methods and the sensitivity of the results to variations in Λ are discussed.

QCD with dynamical Wilson fermions. II

We present results for the QCD spectrum and the matrix elements of scalar and axial-vector densities at β=6/g2=5.4, 5.5, 5.6. The lattice update was done using the hybrid Monte Carlo algorithm to include two flavors of dynamical Wilson fermions. We have explored quark masses in the range ms≤mq≤3ms. The results for the spectrum are similar to quenched simulations and mass ratios are consistent with phenomenological heavy-quark models. The results for matrix elements of the scalar density show that the contribution of sea quarks is comparable to that of the valence quarks. This has important implications for the pion-nucleon σ term.

Dynamical generation of flavour

We propose the generation of Standard Model fermion hierarchy by the extension of renormalizable SO(10) GUT with O(N (g) ) family gauge symmetry. In this scenario, Higgs representations of SO(10) also carry family indices and are called Yukawons. Vacuum expectation values of these Yukawon fields break GUT and family symmetry and generate MSSM Yukawa couplings dynamically. We have demonstrated this idea using Higgs irrep, ignoring the contribution of 1 2 0-plet which is, however, required for complete fitting of fermion mass-mixing data. The effective MSSM matter fermion couplings to the light Higgs pair are determined by the null eigenvectors of the MSSM-type Higgs doublet superfield mass matrix . A consistency condition on the doublet (1,2,+/- 1]) mass matrix ( 0) is required to keep one pair of Higgs doublets light in the effective MSSM. We show that the Yukawa structure generated by null eigenvectors of are of generic kind required by the MSSM. A hidden sector with a pair of (S (a b) ; I center dot (a b) ) fields breaks supersymmetry and facilitates 0. SUSY breaking is communicated via supergravity. In this scenario, matter fermion Yukawa couplings are reduced from 15 to just 3 parameters in MSGUT with three generations.

Conjugate Model for Heat and Mass Transfer of Porous Wall in the High Temperature Gas Flow

Heat and mass transfer of a porous permeable wall in a high temperature gas dynamical flow is considered. Numerical simulation is conducted on the ground of the conjugate mathematical model which includes filtration and heat transfer equations in a porous body and boundary layer equations on its surface. Such an approach enables one to take into account complex interaction between heat and mass transfer in the gasdynamical flow and in the structure subjected to this flow. The main attention is given to the impact of the intraporous heat transfer intensity on the transpiration cooling efficiency.

The center of mass and center of charge of the electron

9th Biennial Conference on Classical and Quantum Relativistic Dynamics of Particles and Fields (IARD)

eta-production on the proton via electromagnetic and hadronic probes

The reactions pi(-)p -> eta n and gamma p -> eta p are investigated within a dynamical coupled-channels model of meson production reactions in the nucleon resonance region The meson-baryon channels included are pi N, pi Delta, sigma N, and rho N The direct eta-photoproduction process is studied within a formalism based on a chiral constituent quark model approach, complemented with a one-gluon-exchange mechanism, to take into account the breakdown of the SU(6)circle times O(3) symmetry In the models search, the following known nucleon resonances are embodied S-11(1535), S-11(1650), P-11(1440), P-11(1710), P-13(1720), D-13(1520), D-13(1700), D-15(1675), and F-15(1680). Data for the pi(-)p -> eta n reaction from threshold up to a total center-of-mass energy of W approximate to 2 GeV are satisfactorily reproduced For the photoproduction channel: two additional higher mass known resonances, P-13(1900) and F-15(2000), are also considered However, reproducing the data for gamma p -> eta p requires, within our approach, two new nucleon resonances, for which we extract, mass and width

eta photoproduction on the proton in a chiral constituent quark approach via a one-gluon-exchange model

A formalism based on a chiral quark model (chi QM) approach complemented with a one-gluon-exchange model, to take into account the breakdown of the SU(6)circle times O(3) symmetry, is presented. The configuration mixing of wave functions for nucleon and resonances are derived. With few adjustable parameters, differential cross-section and polarized-beam asymmetry for the gamma p -> eta p process are calculated and successfully compared with the data in the center-of-mass energy range from threshold to 2 GeV. The known resonances S-11(1535), S-11(1650), P-13(1720), D-13(1520), and F-15(1680), as well as two new S-11 and D-15 resonances, are found to be dominant in the reaction mechanism. Moreover, connections among the scattering amplitudes of the chi QM approach and the helicity amplitudes, as well as decay widths of resonances, are established. Possible contributions from the so-called missing resonances are investigated and found to be negligible.

General SU(2)(L) x SU(2)(R) x U(1)(EM) sigma model with external sources, dynamical breaking and spontaneous vacuum symmetry breaking

We give a general SU(2)(L) x SU(2)(R) x U(1)(EM) sigma model with external sources, dynamical breaking and spontaneous vacuum symmetry breaking, and present the general formulation of the model. It is found that sigma and pi(0) without electric charges have electromagnetic interaction effects coming front the internal structures. A general Lorentz transformation relative to external sources J(gauge) - (J(A mu) J(A mu)(kappa)) derived, using the general Lorentz transformation and the four-dimensional current of nuclear matter of the ground si ate with J(gauge) = 0, we give the four-dimensional general relations between the different currents of nuclear matter systems with J(gauge) not equal 0 and those with J(gauge) = 0. The relation of the density's coupling with external magnetic field is derived, which conforms well to dense nuclear matter in a strong magnetic field. We show different condensed effects in strong interaction about fermions and antifermions, and give the concrete scalar and pseudoscalar condensed expressions of sigma(0) and pi(0) bosons. About different dynamical breaking and spontaneous vacuum symmetry breaking, the concrete expressions of different mass spectra are obtained in field theory. This paper acquires the running spontaneous vacuum breaking value sigma'(0), and obtains the spontaneous vacuum breaking in tenus of the running sigma'(0), which make nucleon, sigma, and pi particles gain effective masses. We achieve both the effect of external sources and nonvanishing value of the condensed scalar and pseudoscalar paticles. It is deduced that the masses of nucleons, sigma and pi generally depend on different external sources.