119153029
Metric-torsional conformal gravity
Abstract When in general geometric backgrounds the metric is accompanied by torsion, the metric conformal properties should correspondingly be followed by analogous torsional conformal properties; however a combined metric torsional conformal structure has never been found which provides a curvature that is both containing metric-torsional degree of freedom and conformally invariant: in this Letter we construct such a metric-torsional conformal curvature. We proceed by building the most general action, then deriving the most general system of field equations; we check their consistency by showing that both conservation laws and trace condition are verified. Final considerations and comments are outlined.
118464233
Hadronic Electroweak Spin-Torsion Interactions
In a previous paper we considered matter field equations with torsional contribution giving rise to special interactions which have eventually been shown to have the same structure of the electroweak forces; the results obtained in that paper are extended in this paper to the whole first generation of fermions. As a possible outlook the extension to all generations is discussed and consequently some speculations about the value for the mass of the Higgs field are presented.
118141049
Gravitationally Generated Interactions
Starting from a 5D-Riemannian manifold, we show that a reduction mechanism to 4D-spacetimes reproduces Extended Theories of Gravity (ETGs) that are direct generalizations of Einstein's gravity. In this context, the gravitational degrees of freedom can be dealt under the standard of spacetime deformations. Besides, such deformations can be related to the mass spectra of particles. The intrinsic non-linearity of ETGs gives an energy-dependent running coupling, while torsion gives rise to interactions among spinors displaying the structure of the weak forces among fermions. We discuss how this scheme is compatible with the known observational evidence and suggest that eventual discrepancies could be detected in experiments, as ATLAS and CMS, today running at LHC (CERN). We finally discuss the consequences of the present approach in view of unification of physical interactions.
118477044
A Discussion on Dirac Field Theory, No-Go Theorems and Renormalizability
We study Dirac field equations coupled to electrodynamics with metric and torsion fields: we discuss how special spinorial solutions are incompatible with torsion; eventually these results will be used to sketch a discussion on the problem of renormalizability of point-like particles.
119247598
From the Torsion Tensor for Spinors to the Weak Forces for Leptons
We consider a geometric approach to field theory in which torsion is present beside gravity and also electrodynamics for the matter field equations, and we develop the consequences of the torsion-spin coupling for the spinor fields; we show that these interactions have the structure of the weak interactions acting among leptons: we discuss the implications for the standard model of fundamental interactions of elementary fields in the perspective of the foundations of unification in theoretical physics.
119124702
Dirac fields in f(R)-gravity with torsion
We study f(R)-gravity with torsion in the presence of Dirac massive fields. Using the Bianchi identities, we formulate the conservation laws of the theory and we check the consistency with the matter field equations. Further, we decompose the field equations in torsionless and torsional terms: we show that the nonlinearity of the gravitational Lagrangian reduces to the presence of a scalar field that depends on the spinor field; this additional scalar field gives rise to an effective stress?energy tensor and plays the role of a scale factor modifying the normalization of Dirac fields. Problems for fermions regarding the positivity of energy and the particle?antiparticle duality are discussed.
109176666
The data acquisition system of the SuperB-SVT beam test
Abstract Prototypes of a new hybrid pixel detector and a high resistivity detector with short strips, developed by the VIPIX Collaboration and aimed at equipping the layer-0 of the SuperB vertex detector, have been tested in September 2011 with a 120 GeV pion beam at the SPS H6 beam line at CERN. They are placed at the center of a reference telescope consisting of six planes of silicon detector with a double-sided strip readout. Both the telescope and the detectors under test (DUT) are equipped with a custom-design, data-push digital readout. The main elements of the trigger and data acquisition system are two VME boards (EDRO) organized in a master-slave configuration and responsible for programming the front-end chips of both the telescope and the DUT. The master board distributes a global synchronization clock and the triggers to all devices, including two 3×3 analog-maps matrices placed behind the DUT and supplied with an independent readout. Both EDROs act as event-fragment builders. These are sent out to a remote PC for event building, buffering and storage.
16866620
Analysis of charmonium production at fixed-target experiments in the NRQCD approach
We present an analysis of the existing data on charmonium hadro-production based on non-relativistic QCD (NRQCD) calculations at the next-to-leading order (NLO). All the data on J/psi and psi' production in fixed-target experiments and on pp collisions at low energy are included. We find that the amount of color octet contribution needed to describe the data is about 1/10 of that found at the Tevatron.
22317714
2D and 3D thin pixel technologies for the Layer0 of the SuperB Silicon Vertex Tracker
The high luminosity asymmetric e+e− collider SuperB, recently approved by the Italian Government, is designed to deliver a luminosity greater than 1036cm−2s−1 with moderate beam currents and a reduced center of mass boost with respect to earlier B-Factories. An improved vertex resolution is required for precise time-dependent measurements and the SuperB Silicon Vertex Tracker will be equipped with an innermost layer of small radius (about 1.5 cm), resolution of 10 µm in both coordinates, low material budget (&#60; 1% X0), and able to withstand a hit background rate of several tens of MHz/cm2. The ambitious goal of designing a thin pixel device matching these stringent requirements is being pursued with specific R&D programs on different technologies: CMOS MAPS, pixel sensors in vertical integration technology and hybrid pixels with small pitch and reduced material budget. The latest results on the characterization of the various pixel devices realized for the SuperB Layer0 will be presented.
120546156
A radiation tolerant phototube power supply for the electromagnetic calorimeter of the HERA-B experiment
Abstract The design of the phototube power supply for the HERA- B Electromagnetic Calorimeter is presented. A choice of the solution on the basis of the Cockcroft–Walton voltage multiplier is validated. Schematics developed are discussed. A special section describes the behaviour of the crucial components under irradiation since radiation tolerance becomes one of the most important items in the severe HERA- B radiation environment. Finally, performance achieved is presented.
54028581
Recent developments on CMOS MAPS for the SuperB Silicon Vertex Tracker
Abstract In the design of the Silicon Vertex Tracker for the high luminosity SuperB collider, very challenging requirements are set by physics and background conditions on its innermost Layer0: small radius (about 1.5 cm), resolution of 10 – 15 μ m in both coordinates, low material budget 1 % X 0 , and the ability to withstand a background hit rate of several tens of MHz / cm 2 . Thanks to an intense R&D program the development of Deep NWell CMOS MAPS (with the ST Microelectronics 130 nm process) has reached a good level of maturity and allowed for the first time the implementation of thin CMOS sensors with similar functionalities as in hybrid pixels, such as pixel-level sparsification and fast time stamping. Further MAPS performance improvements are currently under investigation with two different approaches: the INMAPS CMOS process, featuring a quadruple well and a high resistivity substrate, and 3D CMOS MAPS, realized with vertical integration technology. In both cases specific features of the processes chosen can improve charge collection efficiency, with respect to a standard DNW MAPS design, and allow to implement a more complex in-pixel logic in order to develop a faster readout architecture. Prototypes of MAPS matrix, suitable for application in the SuperB Layer0, have been realized with the INMAPS 180 nm process and the 130 nm Chartered/Tezzaron 3D process and results of their characterization will be presented in this paper.