101.
Detection Rates Of Supersymmetric Relic Particles
- N. Fornengo
Calculations of direct and indirect detection rates of relic neutralinos are
presented in the framework of the Minimal Supersymmetric Standard Model
and compared with the most recent experimental upper bounds. The properties
of neutralino under the hypothesis that some preliminary experimental
results of the DAMA/NaI Collaboration may be indicative of a yearly modulation
effect are examined.
Talk presented by Nicolao Fornengo at "Physics Beyond the Standard Model:
from theory to experiment (Valencia97)", Valencia, Spain, 13--17 October
1997
a
Report on the work done in collaboration with A. Bottino, F. Donato and S. Scopel.
DETECTION RATES OF SUPERSYMMETRIC RELIC
PARTICLES
b
Nicolao FORNENGO
Dipartimento di Fisica Teorica, Universit`a di Torino
and INFN - Sezione di Torino, via...
102.
Lattices And Their Continuum Limits
- P. Teotonio--sobrinho,G. Bimonte,E. Ercolessi,G. Landi,F. Lizzi,G. Sparano
We address the problem of the continuum limit for a system of Hausdorff lattices
(namely lattices of isolated points) approximating a topological space M . The
correct framework is that of projective systems. The projective limit is a universal
space from which M can be recovered as a quotient. We dualize the construction to
approximate the algebra C(M) of continuous functions on M . In a companion paper
we shall extend this analysis to systems of noncommutative lattices (non Hausdoff
lattices).
Address after September 1
st
: Departamento de Fisica Teorica, Facultade de Ciencias, Universitad
de Zaragoza, 50009 Zaragoza, Spain.
1 Introduction
Lattice discretizations have become very popular methods to approximate physical...
103.
Noncommutative Lattices And Their Continuum Limits
- G. Bimonte,E. Ercolessi,G. Landi,F. Lizzi,G. Sparano
We consider finite approximations of a topological space M by noncommutative
lattices of points. These lattices are structure spaces of noncommutative C
-algebras
which in turn approximate the algebra C(M) of continuous functions on M . We
show how to recover the space M and the algebra C(M) from a projective system of
noncommutative lattices and an inductive system of noncommutative C
-algebras,
respectively.
Address after September 1
st
: Departamento de Fisica Teorica, Facultade de Ciencias, Universitad
de Zaragoza, 50009 Zaragoza, Spain.
1 Introduction
Physical models are usually given by a suitable carrier (configuration or phase) space
together with a dynamics on it. Nontrivial topological properties of the carrier space may
have deep consequences...
104.
Lattices And Their Continuum Limits
- G. Bimonte,E. Ercolessi,G. Landi,F. Lizzi,G. Sparano
We address the problem of the continuum limit for a system of Hausdorff lattices
(namely lattices of isolated points) approximating a topological space M . The
correct framework is that of projective systems. The projective limit is a universal
space from which M can be recovered as a quotient. We dualize the construction to
approximate the algebra C(M) of continuous functions on M . In a companion paper
we shall extend this analysis to systems of noncommutative lattices (non Hausdorff
lattices).
Address after September 1
st
: Departamento de Fisica Teorica, Facultade de Ciencias, Universitad
de Zaragoza, 50009 Zaragoza, Spain.
1 Introduction
Lattice discretizations have become very popular methods to approximate physical...
105.
Common Origin Of The Shoulder Structure And Of The Oscillations Of Moments In Multiplicity Distributions In
- A. Giovannini,S. Lupia,R. Ugoccioni
We show, via a simple parametrization of the multiplicity distribution of
charged particles in e
+
e
Gamma
annihilation at the Z
0
peak in terms of the weighted
superposition of two negative binomial distributions, that both the shoulder
structure in the intermediate multiplicity range and the oscillation in sign of
the ratio of factorial cumulants over factorial moments of increasing order are
related to hard gluon radiation.
Talk presented at the
7th International Workshop "Correlations and Fluctuation"
(Nijmegen, The Netherlands, June 30 -- July 6, 1996) and at the
28th International Conference on High Energy Physics -- ICHEP 96
(Warsaw, Poland, July 25--31, 1996).
a
E-mail: giovannini@to.infn.it
b
E-mail: lupia@mppmu.mpg.de
c
E-mail: roberto@thep.lu.se
COMMON ORIGIN OF THE SHOULDER STRUCTURE AND
OF THE OSCILLATIONS...
106.
Sistemes de Lie i l'equació de Riccati matricial
- Joseph Duran, Bernat
El propòsit d'aquest treball és, doncs, revisar el teorema de Lie i la seva demostració i il·lustrar alguns casos d'especial importància sobre els quals els resultats que es coneixen actualment tan sols poden ser trobats en els articles citats anteriorment, que sovint nogaudeixen de suficient claredat i nivell de detall per al lector no especialitzat.En aquest sentit gran part del treball ha consistit a consultar un bon nombre d'articles i seleccionar la informació més adient per tal de realitzar un treball tancat i tan autocontingut com ha estat possible. En conseqüència, una de les tasques amb més dficultat haconsistit a...
107.
Lattices and Their Continuum Limits
- The Erwin; Schrodinger International Pasteurgasse; P. Teotonio-Sobrinho; G. Bimonte; G. Bimonte; E. Ercolessi; E. Ercolessi; G. Landi; G. Landi; F. Lizzi; F. Lizzi; G. Sparano; G. Sparano; P. Teotonio-sobrinho
We address the problem of the continuum limit for a system of Hausdorff lattices (namely lattices of isolated points) approximating a topological space M . The correct framework is that of projective systems. The projective limit is a universal space from which M can be recovered as a quotient. We dualize the construction to approximate the algebra C(M) of continuous functions on M . In a companion paper we shall extend this analysis to systems of noncommutative lattices (non Hausdoff lattices). Address after September 1 st : Departamento de Fisica Teorica, Facultade de Ciencias, Universitad de Zaragoza, 50009 Zaragoza, Spain....
108.
Noncommutative Lattices And Their Continuum Limits
- Bimonte Ercolessi; G. Bimonte; E. Ercolessi; G. Landi; F. Lizzi; P. Teotonio-sobrinho
We consider finite approximations of a topological space M by noncommutative lattices of points. These lattices are structure spaces of noncommutative C -algebras which in turn approximate the algebra C(M) of continuous functions on M . We show how to recover the space M and the algebra C(M) from a projective system of noncommutative lattices and an inductive system of noncommutative C -algebras, respectively. Address after September 1 st : Departamento de Fisica Teorica, Facultade de Ciencias, Universitad de Zaragoza, 50009 Zaragoza, Spain. 1 Introduction Physical models are usually given by a suitable carrier (configuration or phase) space together with...
109.
Supersymmetric Candidates for Dark Matter
- Nicolao Fornengo; Nicolao Fornengo
Direct and indirect detection rates of relic neutralinos are reviewed in the framework of the Minimal Supersymmetric Standard Model. The theoretical estimates are compared with the most recent experimental limits from low--background detectors and neutrino telescopes. The properties of neutralino under the hypothesis that preliminary experimental results of the DAMA/NaI Collaboration may be indicative of a yearly modulation effect are examined. Talk presented at "DM97: Dark matter: perspectives and projects", Osservatorio Astronomico and ICTP, Trieste, 9--11 December 1997 (published in the Proceedings, editor P. Salucci) Report on the work done in collaboration with A. Bottino, F. Donato and S. Scopel....
110.
Relic Neutralinos and Dark Matter
- Nicolao Fornengo; Nicolao Fornengo
We discuss the relevance for supersymmetric theories of the further indication of a possible modulation effect in WIMP direct detection recently reported by the DAMA/NaI Collaboration. The main results of our analysis show that the annual modulation data are widely compatible with an interpretation in terms of a relic neutralino as the major component of dark matter in the Universe, both in the MSSM and in SUGRA schemes. We also discuss the ensuing implications for searches of supersymmetry at accelerators and for indirect searches of neutralino dark matter. Talk presented by Nicolao Fornengo at the International Workshop "Particle Physics and...
111.
Gravitational Effects On The Neutrino Oscillation In Vacuum
- N. Fornengo; C. Giunti; C. W. Kim; J. Song
The propagation of neutrinos in a gravitational field is studied by developing a method of calculating a covariant quantum--mechanical phase in a curved space--time. The result is applied to neutrino propagation in the Schwarzschild metric. Talk presented by Nicolao Fornengo at "Topics in Astroparticle and Underground Physics (TAUP97)," Laboratori Nazionali del Gran Sasso, Italy, 7--11 September 1997 1 Gravitational effects on the neutrino oscillation in vacuum N. Fornengo a , C. Giunti a , C. W. Kim b and J. Song c a Dipartimento di Fisica Teorica, Universit`a di Torino and INFN, Sezione di Torino, via P. Giuria 1, 10125...
112.
Detection Rates of Supersymmetric Relic Particles
- N. Fornengo; Nicolao Fornengo
Calculations of direct and indirect detection rates of relic neutralinos are presented in the framework of the Minimal Supersymmetric Standard Model and compared with the most recent experimental upper bounds. The properties of neutralino under the hypothesis that some preliminary experimental results of the DAMA/NaI Collaboration may be indicative of a yearly modulation effect are examined. Talk presented by Nicolao Fornengo at "Physics Beyond the Standard Model: from theory to experiment (Valencia97)", Valencia, Spain, 13--17 October 1997 a Report on the work done in collaboration with A. Bottino, F. Donato and S. Scopel. DETECTION RATES OF SUPERSYMMETRIC RELIC PARTICLES b...
113.
Von Neumann and Shannon-Wehrl Entropy for Squeezed States and Cosmological Particle Production
- M. Gasperini; M. Gasperini; M. Giovannini; M. Giovannini
We show that the effective coarse graining of a two-mode squeezed density matrix, implicit in the Wehrl approaches to a semiclassical phase-space distribution, leads to results in agreement with previous different definitions of entropy for the process of pair production from the vacuum. We also present, in this context, a possible interpretation of the entropy growth as an amplification (due to the squeezing) of our lack of knowledge about the initial conditions, which gives rise to an effective decoherence of the squeezed density matrix. --------------------------- To appear in the "String gravity and physics at the Planck energy scale " (World...
114.
Normal Modes for Metric Fluctuations in a Class of Higher-Dimensional Backgrounds
- M. Gasperini; M. Giovannini
We discuss a gauge invariant approach to the theory of cosmological perturbations in a higher-dimensonal background. We find the normal modes which diagonalize the perturbed action, for a scalar field minimally coupled to gravity, in a higher-dimensional manifold M of the Bianchi-type I, under the assumption that the translations along an isotropic spatial subsection of M are isometries of the full, perturbed background. We show that, in the absence of scalar field potential, the canonical variables for scalar and tensor metric perturbations satisfy exactly the same evolution equation, and we discuss the possible dependence of the spectrum on the number...
115.
Quantum Chaos and Dynamical Entropy
- Fabio Benatti; Thomas Hudetz; Andreas Knauf
We review the notion of dynamical entropy by Connes, Narnhofer and Thirring and relate it to Quantum Chaos. A particle in a periodic potential is used as an example. This is worked out in the classical and the quantum mechanical framework, for the single particle as well as for the corresponding gas. The comparison does not only support the general assertion that quantum mechanics is qualitatively less chaotic than classical mechanics. More specifically, the same dynamical mechanism by which a periodic potential leads to a positive dynamical entropy of the classical particle may reduce the dynamical entropy of the quantum...
116.
Metric Perturbations in Dilaton-Driven Inflation
- Brustein Gasperini; R. Brustein; M. Gasperini; M. Giovannini; V. F. Mukhanov; G. Veneziano
We compute the spectrum of scalar and tensor metric perturbations generated, as amplified vacuum fluctuations, during an epoch of dilaton-driven inflation of the type occurring naturally in string cosmology. In the tensor case the computation is straightforward while, in the scalar case, it is made delicate by the appearance of a growing mode in the familiar longitudinal gauge. In spite of this, a reliable perturbative calculation of perturbations far outside the horizon can be performed by resorting either to appropriate gauge invariant variables, or to a new coordinate system in which the growing mode can be "gauged down". The simple...
117.
Graceful Exit In Quantum String Cosmology
- Gasperini Theory; M. Gasperini; J. Maharana; G. Veneziano
We write an O(d; d)-covariant Wheeler-De Witt equation in the (d 2 + 1)-dimensional minisuperspace of low-energy cosmological string backgrounds. We discuss explicit examples of transitions between two duality-related cosmological phases, and we find a finite quantum transition probability even when the two phases are classically separated by a curvature singularity. This quantum approach is completely free from operator ordering ambiguities as a consequence of the duality symmetries of the string effective action. To appear in Nucl. Phys. B CERN-TH/96-32 February 1996 1 Permanent address: Dipartimento di Fisica Teorica, Via P. Giuria 1, 10125 Turin, Italy. 2 Jawaharlal Nehru Fellow....
118.
Quantum Squeezing and Cosmological Entropy Production
- Gasperini Theory; M. Gasperini; M. Giovannini
The entropy growth in a cosmological process of pair production is completely determined by the associated squeezing parameter, and is insensitive to the number of particles in the initial state. The total produced entropy may represent a significant fraction of the entropy stored today in the cosmic black-body radiation, provided pair production originates from a change in the background metric at a curvature scale of the Planck order. To appear in Class. Quantum Grav. CERN-TH.6954/93 July 1993 y Essay written for the 1993 Awards for Essays on Gravitation of the Gravity Research Foundation, and awarded with Honorable Mention. Permanent address:...
119.
Singularity And Exit Problems In Two-Dimensional String Cosmology
- Gasperini And; M. Gasperini; G. Veneziano
A broad class of two-dimensional loop-corrected dilaton gravity models exhibit cosmological solutions that interpolate between the string perturbative vacuum and a background with asymptotically flat metric and linearly growing dilaton. The curvature singularities of the corresponding tree-level solutions are smoothed out, but no branch-change occurs. Thus, even in the presence of a non-perturbative potential, the system is not attracted by physically interesting fixed points with constant dilaton, and the exit problem of string cosmology persists. To appear in Phys. Lett. B CERN-TH/96-165 June 1996 1 Permanent address: Dip. di Fisica Teorica, Un. di Torino, Via P. Giuria 1, 10125 Turin,...
120.
Birth of the Universe as Quantum Scattering in String Cosmology
- M. Gasperini; G. Veneziano
In a Wheeler-De Witt approach to quantum string cosmology, the present state of the Universe arises from the scattering and reflection of the wave function representing the initial string vacuum in superspace. This scenario is described and compared with the more conventional quantum cosmology picture, in which the birth of the Universe is represented as a process of tunnelling "from nothing" in superspace. Awarded the "Third Prize" in the 1996 Awards for Essays on Gravitation (Gravity Research Foundation, Wellesley Hills, Ma) ----------------------------- To appear in Gen. Rel. Grav. CERN-TH/96-49 February 1996 1 Permanent address: Dipartimento di Fisica Teorica, Via P....
