I. Lazzizzera

Totem:. a Highly Parallel Chip for Triggering Applications with Inductive Learning Based on the Reactive Tabu Search

The training of a Multi-Layer Perceptron (MLP) classifier is considered as a Combinatorial Optimization task and solved using the Reactive Tabu Search (RTS) method. RTS needs only forward passes (no derivatives) and does not require high precision network parameters. TOTEM, a special-purpose VLSI chip, was developed to take advantage of the limited memory and processing requirements of RTS: the final system effects a very close match between hardware and training algorithm. The RTS algorithm and the design of TOTEM are discussed, together with the operational characteristics of the VLSI chip and some preliminary training and generalization tests on triggering tasks.

A hamiltonian formulation of Yang-Mills theories in the pure temporal gauge

Abstract A canonical hamiltonian quantization of Yang-Mills theories is developed in the pure time-like axial gauge, obtaining for the gluons (photons) a prescription similar to the one originally proposed by Mandelstam and Leibbrandt for the light-like case. In a redundant Hilbert space a physical subspace with positive-semidefinite inner product is defined, where the Gauss law and Poincare covariance are recovered and the perturbative scattering matrix is unitary.

Yang-Mills theories in space-like axial and planar gauges

Abstract The quantization of Yang-Mills theories according to a canonical procedure is studied first in the axial gauge A 3 a ≡ 0. We show that the perturbative S -matrix cannot be expressed in terms of well-defined distributions in a Hilbert space involving only physical states without conflicting with unitarity. We then resort to the space-like planar gauge and show that it is possible to define a perturbative S -matrix at the price of introducing a set of free ghost fields. The S -matrix is unitary in the subspace of the physically acceptable states on which A 3 a vanish.

Advances in the design of the TOTEM neurochip

Abstract The TOTEM neurochip has proved its viability as a system for real-time computation in HEP and space applications requiring high performance for event classification, data mining, and signal processing. ISA and VME boards integrating the TOTEM chip as a coprocessor have been made available to selected experimental groups which reported satisfactory results. This paper presents a new architectural solution yielding higher performance and reduced silicon area. The on-chip computational structures have been entirely redesigned to take advantage of a novel approach to number representation that, at the cost of a provably bounded approximation, leads to a much-reduced silicon area, lower power dissipation, and faster computation. This approach is validated by simulation results on experimental data, as presented in the paper.

Polymer topology and Chern-Simons field theory

Abstract In this paper the statistical mechanical problem of two topologically linked polymers is related to a topological Ginzburg-Landau model coupled to two Chern-Simons field theories. The Chern-Simons fields play the role of propagators of the topological interactions. The effects of the topological constraints is investigated using the method of effective potential in one-loop approximation.

Role of neural networks in the search of the Higgs boson at LHC

Abstract We show that neural network classifiers can be helpful to discriminate Higgs production from background at LHC in the Higgs mass range M H ∼ 200 GeV. We employ a common feed-forward neural network trained by the backpropagation algorithm for off-line analysis and the neural chip totem , trained by the Reactive Tabu Search algorithm, which could be used for on-line analysis.We show that neural network classifiers can be helpful to discriminate Higgs production from background at LHC in the Higgs mass range M= 200 GeV. We employ a common feed-forward neural network trained by the backpropagation algorithm for off-line analysis and the neural chip Totem, trained by the Reactive Tabu Search algorithm, which could be used for on-line analysis.

FIELD THEORY OF N ENTANGLED POLYMERS

We formulate a field theory capable of describing a canonical ensemble of N polymers subjected to linking number constraints in terms of Feynman diagrams.

Boundary conditions and spurious singularities in classical gauge theories

Abstract We show, at the classical level, that the so-called spurious singularities, characteristic of the axial gauges, are related to the boundary conditions one can impose on the potentials. In the spacelike case A 3 = 0 they are needed in order to avoid non-physical constraints on the external currents.

Second topological moment 〈m2〉 of two closed entangled polymers

We calculate exactly by field theoretical techniques the second topological moment hm 2 i of entanglement of two closed polymersP1 andP2. This result is used to estimate approximately the mean square average of the linking number of a polymer P1 in solution with other polymers.

A Chern-Simons field theory description of topologically linked polymers

Abstract In this paper the statistical mechanics of two topologically linked polymers is investigated. We show that this problem can be related to a n-components topological Ginzburg-Landau model with the addition of Chern-Simons terms. The Chern-Simons fields play the physical role of carriers of the interactions which enforce the topological constraints.