4,944 research outputs found
Measuring the SUSY Breaking Scale at the LHC in the Slepton NLSP Scenario of GMSB Models
We report a study on the measurement of the SUSY breaking scale sqrt(F) in
the framework of gauge-mediated supersymmetry breaking (GMSB) models at the
LHC. The work is focused on the GMSB scenario where a stau is the
next-to-lightest SUSY particle (NLSP) and decays into a gravitino with lifetime
c*tau_NLSP in the range 0.5 m to 1 km. We study the identification of
long-lived sleptons using the momentum and time of flight measurements in the
muon chambers of the ATLAS experiment. A realistic evaluation of the
statistical and systematic uncertainties on the measurement of the slepton mass
and lifetime is performed, based on a detailed simulation of the detector
response. Accessible range and precision on sqrt(F) achievable with a counting
method are assessed. Many features of our analysis can be extended to the study
of different theoretical frameworks with similar signatures at the LHC.Comment: 28 pages, 12 figures (18 eps files). Revised version v2(published in
JHEP): Some important corrections and additions to v
Aspects of GMSB Phenomenology at TeV Colliders
The status of two on-going studies concerning important aspects of the
phenomenology of gauge-mediated supersymmetry breaking (GMSB) models at TeV
colliders is reported. The first study deals with the characteristics of the
light Higgs boson spectrum allowed by the (minimal and non-minimal) GMSB
framework. Today's most accurate GMSB model generation and two-loop
Feynman-diagrammatic calculation of m_h have been combined. The Higgs masses
are shown in dependence of various model parameters at the messenger and
electroweak scales. In the minimal model, an upper limit on m_h of about 124
GeV is found for m_t = 175 GeV. The second study is focused on the measurement
of the fundamental SUSY breaking scale sqrt(F) at the LHC in the GMSB scenario
where a stau is the next-to-lightest SUSY particle (NLSP) and decays into a
gravitino with c*tau_NLSP in the range 0.5 m to 1 km. This implies the
measurement of mass and lifetime of long lived sleptons. The identification is
performed by determining the time of flight in the ATLAS muon chambers.
Accessible range and precision on sqrt(F) achievable with a counting method are
assessed.Comment: 22 pages, 9 figures (12 eps files). Report of the GMSB SUSY Working
Group, Workshop "Physics at TeV Colliders", Les Houches, 7-18 June 1999.
Revised version v3: A few typos correcte
Geometria e progetto. Ipotesi di riuso per il palazzo Vernazza a Castri
DallâAntichitĂ al Rinascimento, da Pitagora a Keplero, aritmetica, geometria, musica e astronomia hanno indagato il numero, lo spazio, il suono e il movimento dei corpi celesti. Queste quattro discipline venivano giĂ pensate e insegnate da Platone come un insieme unitario, che fondeva lo studio degli oggetti matematici con lâaspirazione filosofica al vero, al bello e al bene. Il Quadrivium viene reinterpretato in questo lavoro e lâedificio diviene testimone, testo parlante, memoria scritta in molti linguaggi e restituisce al lettore di oggi un patrimonio un tempo riservato a pochi. Il Palazzo Vernazza di Castri di Lecce Ăš studiato in questa sperimentazione progettuale a partire dalla riscoperta della sua misura storica, con il contributo delle moderne tecniche di rilievo che hanno supportato questi studi, allo scopo di assegnare al progetto contemporaneo una base linguistica invisibile, un alfabeto che strutturi la costruzione del nuovo
Floquet Chern Insulators of Light
Achieving topologically-protected robust transport in optical systems has
recently been of great interest. Most topological photonic structures can be
understood by solving the eigenvalue problem of Maxwell's equations for a
static linear system. Here, we extend topological phases into dynamically
driven nonlinear systems and achieve a Floquet Chern insulator of light in
nonlinear photonic crystals (PhCs). Specifically, we start by presenting the
Floquet eigenvalue problem in driven two-dimensional PhCs and show it is
necessarily non-Hermitian. We then define topological invariants associated
with Floquet bands using non-Hermitian topological band theory, and show that
topological band gaps with non-zero Chern number can be opened by breaking
time-reversal symmetry through the driving field. Furthermore, we show that
topological phase transitions between Floquet Chern insulators and normal
insulators occur at synthetic Weyl points in a three-dimensional parameter
space consisting of two momenta and the driving frequency. Finally, we
numerically demonstrate the existence of chiral edge states at the interfaces
between a Floquet Chern insulator and normal insulators, where the transport is
non-reciprocal and uni-directional. Our work paves the way to further exploring
topological phases in driven nonlinear optical systems and their optoelectronic
applications, and our method of inducing Floquet topological phases is also
applicable to other wave systems, such as phonons, excitons, and polaritons
Web-mediated communication experiences at Istituto Nazionale di Geofisica e Vulcanologia
The newer communication tools have changed the relationship between science and society. Internet
pervasiveness led citizens to rapidly inform through on line sources, and, on the other hand, to provide
themselves information. From an institutional communication' perspective this new sociotechnical
landscape forces scientists to rapidly adequate to web population requirements.
Questions and comments posted to INGV web sites during the 2009 L'Aquila (Italy) seismic sequence
gave significant hints about demand of information. They included: questions concerning possible
evolution of the sequence; clarifications about news reported by media, asking for detailed explanations
and/or qualified opinions; requests for help in providing information to population; notices about
information available on INGV web sites; communication of felt seismic effects.
P eople who post questions to INGV institutional web sites are themselves information suppliers, in
providing: what they felt, in case of posting macroseismic effects; what they heard about the earthquake
from other sources; how they feel (worried, confident, grateful ...); what they know and what they want to
know; what they actually understand from the scientific website.
From the point of view of a scientific organization, this kind of web-mediated communication is precious in
that it can reveal and provide many clues about: 1) public expectations and understanding of on going
scientific activities 2) to what extent information dissemination, communication and outreach activities
can be considered effective or to which extent they need improvements.
A mutual approaching is needed. Seismologists acting as responders during an emergency perform a
delicate job: they have to be transparent and make themselves understood; comprehension of scientific
information would benefit of appropriate outreach activities carried on during all the time.
Consisting the INGV web disseminating system of several institutional and thematic web sites, similar
patterns of questions and comments emerge: "network effect", when questions are posted at the end of a
navigation session through different web sites, and may not pertain to the content of that specific website;
"resonance effect", when more questions about earthquakes are posted soon after a big one. A "welcome"
effect is also manifest, as experts providing accurate replies in a timely fashion stimulate web visitors in
posting new questions.
Case studies of web-mediated communication will be discussed, as experimented by the Institute through
the nodes of its web disseminating system
Contribution to the study of the Apulian microplate geodynamics
The fragmentation of the collisional border
between the African and European plates has also originated
the Apulian (Adriatic) microplate. Recent studies
show the possibility of a non-unitary geodynamic
evolution of this microplate: palaeomagnetic data from
North-Western Greece and Southern Apulia indicate a
different rotational behaviour. Between 41' and 43'
latitude North, regional strike-slip fault systems cut
crosswise the Adriatic basin, breaking the Adriatic
block in at least two minor elements. The intense seismicity
points out an active defonnational area. In the
same region also other geophysical data identify a transitional
zone
Ultrahigh energy neutrino scattering onto relic light neutrinos in galactic halo as a possible source of highest energy extragalactic cosmic rays
The diffuse relic neutrinos with light mass are transparent to Ultrahigh
energy (UHE) neutrinos at thousands EeV, born by photoproduction of pions by
UHE protons on relic 2.73 K BBR radiation and originated in AGNs at cosmic
distances. However these UHE s may interact with those (mainly heaviest
, and respective antineutrinos) clustered into HDM
galactic halos. UHE photons or protons, secondaries of scattering,
might be the final observed signature of such high-energy chain reactions and
may be responsible of the highest extragalactic cosmic-ray (CR) events. The
chain-reactions conversion efficiency, ramifications and energetics are
considered for the October 1991 CR event at 320 EeV observed by the Fly's Eye
detector in Utah. These quantities seem compatible with the distance, direction
and power (observed at MeV gamma energies) of the Seyfert galaxy MCG 8-11-11.
The interaction probability is favoured by at least three order of
magnitude with respect to a direct scattering onto the Earth atmosphere.
Therefore, it may better explain the extragalactic origin of the puzzling 320
EeV event, while offering indirect evidence of a hot dark galactic halo of
light (i.e., tens eV) neutrinos, probably of tau flavour.Comment: 25 pages, 1 figure minor corrections, updated references. In press in
AP
Associated production of a light Higgs boson and a chargino pair in the MSSM at linear colliders
In the Minimal Supersymmetric Standard Model (MSSM), we study the light
Higgs-boson radiation off a light-chargino pair in the process e+e- -> h chi^+
chi^- at linear colliders with \sqs=500 GeV. We analyze cross sections in the
regions of the MSSM parameter space where the process can not proceed via
on-shell production and subsequent decay of either heavier charginos or the
pseudoscalar Higgs boson A. Cross sections up to a few fb's are allowed,
according to present experimental limits on the Higgs-boson, chargino and
sneutrino masses. We also show how a measurement of the process production rate
could provide a determination of the Higgs-boson couplings to charginos.Comment: 26 pages, 9 figures; figure misplacement fixed; to appear in
Eur.Phys.J.
Yet another way to measure
We show that the CKM phase can be extracted from measurement
of the time dependent rates in the decays and
, where , , , , ,
. These channels have a large asymmetry between decays of
and into the same final state. Even though the branching ratios are
small, their sensitivity to can be competitive with decays into
and .Comment: 5 pages, some clarifications and references adde
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