Transcript Bollettino Settimanale - Dipartimento di Fisica

Bollettino Settimanale
Lunedì 27 febbraio 2017
AULA CONVERSI ORE 14.00
SEMINARIO TEORICO INFN
Martedì 28 febbraio 2017
AULA CONVERSI ORE 16.00
SEMINARIO GENERALE
Mercoledì 1 Marzo 2017
AULA RASETTI ORE 14.00
SEMINARI ICRA
Finite time thermodynamics and quantitative Parametric resonances: from single atoms Gravitational waves from coalescing binary
analysis of Clausius inequality
neutron stars: interfacing analytical with
to many-body systems
numerical results
Giovanni Jona-Lasinio (Sapienza Università di Roma) Emanuele Dalla Torre
Prof. Alessandro Nagar
(Bar-Ilan University, Israel)
In the context of driven diffusive systems, for
(IHES (Institute d'Hautes Etudes Scientifiques)thermodynamic transformations over a large but finite I will open my talk by explaining the Paris)
time interval we derive an expansion of the energy fundamental concept of parametric resonance
balance around the quasi static limit. In particular, we and giving examples of some practical It is discussed the interfacing between analytic
characterize the transformations which minimize the application (Paul traps, Kapitza pendulum). I and numerical treatments of gravitational waves
energy dissipation and describe the optimal correction will then clarify why the existence of this from coalescing binary neutron stars.
to the quasi-static limit. Surprisingly, in the case of phenomenon in many-body systems is still
transformations between homogeneous equilibrium debated. Although it is believed that large
states of an ideal gas, the optimal transformation is a systems cannot display true parametric
sequence of inhomogeneous equilibrium states.
resonances, I will overview some exceptions to
this general rule. In the last part of the talk, I
will describe some new results on the
dynamics of periodically-driven many-body
AULA CONVERSI ORE 15.00
quantum systems.
SEMINARIO INFN-Fisica
particelle elementari
sperimentale
Interpretation of the cosmic ray positron and
antiproton fluxes
Paolo Lipari (INFN – Sezione di Roma)
The spectral shape of cosmic ray positrons and
antiprotons has been accurately measured in the
broad kinetic energy range 1-350 GeV. In the higher
part of this range (E > 30 GeV) the positron/antiproton
flux ratio has the approximately constant value 2.04+0.04, that is consistent with being equal to the ratio
e+/pbar calculated for the conventional mechanism of
production, where the antiparticles are created as
secondaries in the inelastic interactions of primary
cosmic rays with interstellar gas.
The positron/antiproton ratio at lower energy is
significantly higher but in the entire energy range 1350 GeV, the flux ratio is consistent with being equal
to ratio of the production rates in the conventional
mechanism, since the low energy antiprotons
production is kinematically suppressed. These results
strongly suggest that cosmic ray positrons and
antiprotons have a common origin as secondaries in
hadronic interactions. This conclusion has broad
implications for the astrophysics of cosmic rays in the
Galaxy.
Giovedì 2 marzo 2017
AULA CONVERSI ORE 16.00
SEMINARIO DI STRUTTURA DELLA
MATERIA
A Statistical Physics Approach to Social
Systems in the Age of Digital Data
Andrea Baronchelli (London University)
The paradigm of complexity, summarised by the
motto “more is different”, is not new. Yet it is the
data explosion that we witness today, fuelled by
the Internet and cheap sensors, that is allowing
us to observe the actual behaviour of many
complex social systems for the first time. As a
result, many collective phenomena that used to
be addressed qualitatively are now calling for a
quantitative comprehension, and Statistical
Physics and Network Science have taken up the
challenge. In this talk, I will show how the study of
ordering dynamics and diffusion can be extended
from Statistical Physics to problems in Social and
Cognitive Sciences, resolving long-standing
issues and opening new research directions both
in those disciplines and within Physics itself. I will
present examples ranging from the emergence of
social consensus to the dynamics of human
exploration of physical and non-physical (i.e.,
mental) spaces.
Venerdì 3 marzo 2017