Elliptic boundary value problems with measurable coefficients and explosive boundary conditions

This Phd thesis follows two different directions, always related to elliptic boundary value problems. The first one concerns existence and regularity results for a wide class of non coercive operators with convection or drift lower order terms. The second one focuses on asymptotic behaviour of large solutions, namely solutions that blows up to infinity at the boundary of the domain, to semilinear elliptic problems

Finite temperature one-point functions in non-diagonal integrable field theories: the sine-Gordon model

We study the finite-temperature expectation values of exponential fields in the sine-Gordon model. Using finite-volume regularization, we give a low-temperature expansion of such quantities in terms of the connected diagonal matrix elements, for which we provide explicit formulas. For special values of the exponent, computations by other methods are available and used to validate our findings. Our results can also be interpreted as a further support for a previous conjecture about the connection between finite- and infinite-volume form factors valid up to terms exponentially decaying in the volume.Comment: 24 pages, 15 figure

Electroweak Radiative Corrections to Higgs Production via Vector Boson Fusion using SCET: Numerical Results

Electroweak radiative corrections are computed for Higgs production through vector boson fusion, qq->qqH, which is one of the most promising channels for detecting and studying the Higgs boson at the LHC. Using soft-collinear effective theory, we obtain numerical results for the resummed logarithmic contributions to the hadronic cross section at next-to-leading logarithmic order. We compare our results to HAWK and find good agreement below 2 TeV where the logarithms do not dominate. The SCET method is at its best in the high LHC energy domain where the corrections are found to be slightly larger than predicted by HAWK and by other one-loop fixed order approximations. This is one of the first tests of this formalism at the level of a hadronic cross section, and demonstrates the viability of obtaining electroweak corrections for generic processes without the need for difficult electroweak loop calculations.Comment: Some minor corrections, 4 refs. added. arXiv admin note: text overlap with arXiv:1011.150

Precise Timing of the X-ray Pulsar 1E 1207.4-5209: A Steady Neutron Star Weakly Magnetized at Birth

We analyze all X-ray timing data on 1E 1207.4-5209 in supernova remnant PKS 1209-51/52 gathered in 2000-2005, and find a highly stable rotation with P=424.130451(4) ms and period derivative of (9.6 +/- 9.4)E-17 s/s. This refutes previous claims of large timing irregularities in these data. In the dipole spin-down formalism, the 2-sigma upper limit on period derivative implies an energy loss rate < 1.5E32 ergs/s, surface magnetic field strength B_p < 3.5E11 G, and characteristic age tau > 24 Myr. This tau exceeds the remnant age by 3 orders of magnitude, requiring that the pulsar was born spinning at its present period. The X-ray luminosity of 1E 1207.4-5209, L(bol) ~= 2E33 ergs/s at 2 kpc, exceeds its spin-down energy loss, implying that L(bol) derives from residual cooling, and perhaps partly from accretion of supernova debris. The upper limit on B_p is small enough to favor the electron cyclotron model for at least one of the prominent absorption lines in its soft X-ray spectrum. This is the second demonstrable case of a pulsar born spinning slowly and with a weak B-field, after PSR J1852+0040 in Kesteven 79.Comment: 5 pages, 2 figure, Latex, emulateapj style. Submitted to ApJ Letter

A Score-Driven Conditional Correlation Model for Noisy and Asynchronous Data: an Application to High-Frequency Covariance Dynamics

The analysis of the intraday dynamics of correlations among high-frequency returns is challenging due to the presence of asynchronous trading and market microstructure noise. Both effects may lead to significant data reduction and may severely underestimate correlations if traditional methods for low-frequency data are employed. We propose to model intraday log-prices through a multivariate local-level model with score-driven covariance matrices and to treat asynchronicity as a missing value problem. The main advantages of this approach are: (i) all available data are used when filtering correlations, (ii) market microstructure noise is taken into account, (iii) estimation is performed through standard maximum likelihood methods. Our empirical analysis, performed on 1-second NYSE data, shows that opening hours are dominated by idiosyncratic risk and that a market factor progressively emerges in the second part of the day. The method can be used as a nowcasting tool for high-frequency data, allowing to study the real-time response of covariances to macro-news announcements and to build intraday portfolios with very short optimization horizons.Comment: 30 pages, 10 figures, 7 table

Social Security in Italy-Tunisia agreements

La Sicurezza Sociale assolve ai principi generali di tutela degli indigenti mediante l’assistenza sociale e la previdenza sociale, specifica per garantire i lavoratori. In Italia, in base al principio della territorialità dell’obbligo assicurativo, il lavoratore non comunitario è assoggettato alla legislazione previdenziale e assistenziale del Paese. Il 7 dicembre 1984 viene firmato a Tunisi un accordo amministrativo per l’applicazione della convenzione in materia di sicurezza sociale, tra la Repubblica italiana e la Repubblica tunisina, che dà la possibilità al cittadino tunisino di lavorare in Italia, pur rimanendo sotto la competenza della normativa in materia di sicurezza sociale del proprio Paese di origine. A causa dell’alternanza politica dei Governi Italiani si è giunti ad orientamenti più restrittivi, con l’introduzione della limitazione a equiparare agli italiani solo gli immigrati non comunitari titolari di permesso di soggiorno CE come lungosoggiornanti, oltrepassando, anche quanto previsto dagli accordi bilaterali, tra cui quello italo - tunisino. Ciò ha subordinato l’erogazione di determinate prestazioni previdenziali - assistenziali, discriminando i cittadini tunisini e limitando il godimento dei diritti fondamentali riconosciuti invece ai cittadini italiani.Social Security fulfils the general principles of protection of the needy through social assistance and social security, specific for the protection of workers. In Italy, according to the principle of territoriality of the insurance obligation, the non community worker is subject to the country's social security and welfare legislation. On 7 December 1984 an administrative agreement is signed for the application of the convention on social security signed in Tunis between the Italian Republic and the Tunisian Republic, with the possibility for the Tunisian citizen to work in Italy, while remaining under the responsibility of the legislation on social security in your country of origin. Because of the political alternation of the Italian Governments, more restrictive guidelines have been reached, with the introduction of the limitation to equating to Italians only non-EU immigrants holding EC residence permits as long-staying guests, exceeding even the provisions of bilateral agreements including the Italy - Tunisian one. This has subordinated the provision of certain social security benefits, discriminating against Tunisian citizens and limiting the enjoyment of the fundamental rights recognized to Italian citizens.La Seguridad Social cumple con los principios generales de protección de las personas desfavorecidas a través de la asistencia y los subsidios sociales, específicos para velar por los trabajadores. En Italia, de acuerdo con el principio de la territorialidad del seguro obligatorio, el trabajador no perteneciente a la EE.UU. está sujeto a la legislación de prestaciones sociales italianas. El 7 de diciembre de 1984 se firmó un acuerdo administrativo en Túnez para la aplicación del convenio sobre seguridad social entre la República Italiana y la República de Túnez, el cual brinda al ciudadano tunecino la oportunidad de trabajar en Italia, aunque seguirá bajo la competencia de la normativa de su país de origen. Debido a la alternancia política de los gobiernos italianos, se han llegado a crear unas directrices más restrictivas. Se ha introducido la limitación de equiparar con los italianos solo a los inmigrantes no comunitarios que tengan permiso de residencia de la EE.UU. como residentes de larga duración, obviando las disposiciones de los acuerdos bilaterales, incluido el italo-tunecino. Esto ha subordinado la concesión de ciertos beneficios de prestación y asistencia, discriminando a los ciudadanos tunecinos y limitando el disfrute de los derechos fundamentales reconocidos, en cambio, a los ciudadanos italianos