Bollettino Settimanale
Lunedì 23 febbraio 2015
Martedi’ 24 febbraio 2015
AULA CONVERSI ORE 14.00 AULA CONVERSI ORE 14.30
SEMINARIO INFN-Fisica delle SEMINARIO DI ASTROFICA
particelle elementari
Cosmology above the clouds with SPIDER
Particelle esotiche con lunga
vita media messaggere di Dr. Lorenzo Moncelsi
effetti di nuova fisica: stato California Institute of Technology (CALTECH)
delle
ricerche
con SPIDER is a balloon-borne microwave polarimeter
l'esperimento ATLAS a LHC. designed to measure cosmological B modes on degree
Stefano Giagu
(Sapienza Università di Roma)
Una ampia classe di scenari di fisica
oltre il Modello Standard predicono
l'esistenza di particelle massive con
vite medie confrontabili con le
dimensioni dei rivelatori a LHC come
risultato di vincoli cinematici, di
numeri quantici conservati, o di
accoppiamenti deboli con settori
nascosti della teoria. I decadimenti di
queste particelle produrrebbero
segnali spettacolari quali rilasci
anomali di energia, tracce cariche che
appaiono o scompaiono all'interno dei
vari rivelatori, vertici di decadimento
secondari, getti collimati di leptoni,
tempi di volo anomali e/o rilasci
energetici fuori tempo rispetto
all'istante di interazione, che
l'esperimento ATLAS è in grado di
rivelare. Nel seminario verrà illustrato
lo stato attuale di tali ricerche
utilizzando il campione completo di
dati raccolto nel RunI di LHC ad un
energia nel centro di massa di 7-8
TeV, e le prospettive per il run ad alta
energia che inizierà nella primavera
del 2015. Enfasi particolare verrà
data all'interpretazione dei risultati
ottenuti nel contesto dei modelli di
nuova fisica in grado di offrire una
spiegazione al problema della Materia
Oscura.
angular scales in the presence of Galactic foregrounds.
With six independent telescopes housing a total of ~2000
detectors in the 90 GHz and 150 GHz frequency bands,
SPIDER is the most instantaneously-sensitive CMB
polarimeter deployed on the sky to date. SPIDER was
successfully launched from McMurdo Station, Antarctica in
January 2015 and acquired science data for 16 days. I will
briefly cover the in-flight performance and the expected
analysis challenges. Pending recovery, the SPIDER team
is already planning the next flight, featuring one or two
foreground-optimized channels, which will allow us
constrain the primordial tensor-mode amplitude at the level
of r < 0.03 (99% CL), even in the presence of foregrounds.
Mercoledi’ 25 febbraio
2015
Giovedi’ 26 febbraio 2015
AULA CONVERSI ORE 15.00 AULA AMALDI ORE 15.00
SEMINARIO DI STRUTTURA SEMINARIO DI DIDATTICA E STORIA DELLA FISICA
DELLA MATERIA
Galactic Planetary Science
Universal enhancement of
Prof. Giovanna Tinetti
superconductivity in 2D
semiconductors by electron- (University College London, UK)
Planetary science beyond the boundaries of our Solar System is today in
electron interaction
Francesco Mauri
its infancy. Until a couple of decades ago, the detailed investigation of
the planetary properties was restricted to objects orbiting inside the
Kuiper Belt. Today, we cannot ignore that the number of known planets
has increased by two orders of magnitude nor that these planets
resemble anything but the objects present in our own Solar System.
Whether this fact is the result of a selection bias induced by the kind of
techniques used to discover new planets or simply the proof that the
Solar System is a rarity in the! Milky Way, we do not know yet. What is
clear, though, is that the Solar System has failed to be the paradigm not
only in our Galaxy but even just in the solar neighbourhood. This finding,
although unsettling, forces us to reconsider our knowledge of planets
under a different light and perhaps question a few of the theoretical
pillars on which we base our current understanding. The next decade will
be critical to advance in what we should perhaps call Galactic planetary
science. In this lecture, I review highlights and pitfalls of our current
knowledge of this topic and elaborate on how this knowledge might
arguably evolve in the next decade. More critically, I identify what should
be the mandatory scientific and technical steps to be taken in this
fascinating journey of remote exploration of planets in our Galaxy.
Nota: il seminario si terrà nell'ambito delle Lezioni Fermi
In
two-dimensional
multivalley
semiconductors, at low doping, even a
moderate electron-electron interaction
enhances the response to any
perturbation inducing a valley
polarization. If the valley polarization
is due to the electron-phonon
coupling,
the
electron-electron
interaction results in an enhancement
of the superconducting critical
temperature. By performing first
principles calculations beyond density
functional theory, we prove that this
AULA CONVERSI ORE 16.00
effect accounts for the unconventional
SEMINARIO GENERALE
doping-dependence
of
the
superconducting
transitiontemperature
(Tc)
and
of
the
ma!
gnetic
Charge and heat transport in graphene from
susceptibility measured in LixZrNCl.
first-principles
By finding the conditions for a AULA CARERI ORE 16.00
maximal Tc enhancement, we show
SEMINARIO TEORICO INFN
Francesco Mauri
how weakly-doped two-dimensional
Building electronic devices based on graphene has been semiconductors provide a route
EW vacuum stability and sensitivity to Planck scale
motivating intense research. Field effect transistors have towards high Tc superconductivity.
been demonstrated, but
physics
graphene also holds promise as interconnect, since it can
sustain very high current density. Such current-carrying
Enzo Branchina (Università di Catania)
capacities are several orders of magnitude higher than that
For the present experimental values of the Higgs and top masses, the
of present-day interconnects. Thermal/electrical transportHiggs effective potential becomes unstable at a scale of about $10^10$
properties and charge carrier dynamics after optical
GeV. For this reason, it is widely believed that if new physics shows up
excitations are ruled by the electron and phonon scattering.
only at very high energy scales (Planck scale), this should have no
In order to unravel the capabilities and the limits of
impact on the stability condition of the EW vacuum. It has been recently
graphene devices to sustain very high current density, I will
shown, however, that new physics interactions can strongly affect the
present a detailed analysis of the electron and phonon
vacuum stability condition, so that the stability diagram of the Standard
scattering processes
based on both first-principles
Model can be very different from the diagram (obtained ignoring new
electronic-structure calculations and experimental phonon
physics) that is usually presented. This has far reaching theoretical and
measurements. Such detailed knowledge of the electronphenomenological consequences. In particular, despite claims to the
phonon and phonon-phonon interactions has allowed us to
contrary, higher precision measurements of the top and Higgs masses
study both the thermal conductivity and the origin of
will not provide any definite answer on the fate of our universe, i.e. they
charge-current saturation in graphene at high field in the
will not tell us whether we live in a stable or metastable vacuum state, or
framework of Boltzmann transport theory.
at the edge of stability (as often stated).
Venerdì 27 febbraio
2015
SALA DIREZIONE INFN
ore 16.00
SEMINARIO
STRUTTURA
DELLA MATERIA
A new paradigm for modeling:
a
virtual
multifrequency
spectrometer
Prof. V. Barone (Scuola
Normale Superiore, Pisa)
The subtle interplay of several
different effects still makes the
interpretation and analysis of
experimental spectra in terms of
structural and dynamic characteristics
a very challenging task. In this
context theoretical studies can be
very helpful and this is the reason
behind the rapid evolution of
computational spectroscopy from a
highly specialized research field
toward a versatile and widespread
tool. In this presentation I will sketch
the most significant developments
performed also in the framework of
the ERC Advanced Grant DREAMS.
Integration into a general purpose
computational chemistry package
offers a fully automatic evaluation of
one-photon
electronic
spectra,
starting from several electronic
models, ranging from fully QM
descriptions to discrete/continuum
QM/MM/PCM models. Additionally,
introduction of effective DFT models
allows reliable studies of compounds
of biological or technological interest.
Some specific examples will be
sketched to illustrate our recent
integrated approach.