Tag Archives: Evento scientifico

L’esperimento Qubic si propone la misura dei modi B di polarizzazione con una sensibilità sul parametro r (rapporto tra l’ampiezza delle perturbazioni tensoriali/scalari) pari a circa 2×10-2 in tre anni di presa dati. Si tratta di un passo ulteriore nel miglioramento dell’attuale limite di Bicep2+Planck (r

Particle accelerators based on RF systems have been a remarkable success story since they were proposed 90 years ago by Ising and demonstrated experimentally by Wideröe. Today there are some 30,000 accelerators world-wide, from small industrial accelerators to the Large Hadron Collider, one of mankind largest machines. The maximum beam energy in particle accelerators has for many years followed an exponential increase with time, the so-called Livingston curve. However, progress has slowed down significantly over the last years. At the same time the new technology of plasma-based electron accelerators has emerged with exponential progress since 1980. Acceleration lengths are a factor 100-1000 shorter than in conventional accelerators. Plasmas excited by industrially available lasers have produced accelerating gradients of up to 100 GV/m and electrons at energies up to 4.25 GeV, promising a revolution in the way accelerators are built. Much more compact and cost-effective accelerators can be imagined. The potential of this technology is discussed. National and international activities are summarized. Special emphasis will be placed on the “European Plasma Research Accelerator with Excellence in Applications” (EuPRAXIA) project, the second accelerator-related EU design study in Horizon2020. This EU-financed study aims at proposing a European Research Infrastructure that pioneers a compact plasma accelerator for applications in photon science, High Energy Physics and other fields, like medical imaging applications. EuPRAXIA is supported by a consortium of 16 member institutes and presently 15 associated partner labs in Europe, Asia and the US.

By employing partial wave unitarity arguments I show that: i) the effective description of the di-photon excess in terms of the SM supplemented by a single scalar resonance breaks down at scales of few tens of TeV and ii) in the large width scenario (as hinted by ATLAS) perturbative calculability is endangered in many renormalizable models. I finally discuss under which conditions the data can be accommodated within weakly coupled models.

Recently, several experimental anomalies were discussed as possible signatures for a new light particle. In order to search for such signatures, we have measured the e+e- angular correlation in internal pair creation (IPC) for the the M1 transitions depopulating the 17.6 and 18.15 MeV states in 8Be, and observed anomalous IPC in the latter transition. The observed deviations from the M1 IPC in the case of the 17.6 MeV transition could be explained by the contribution of the background, which has E1 multipolarity. However, E1 or any other mixing cannot explain the measured peak-like deviation in the case of the 18 MeV transition. The deviation between the experimental and theoretical angular correlations is significant and can be described by assuming the creation and subsequent decay of a boson with mass M0c2 =16.70 MeV. The branching ratio of the e+e- decay of such a boson to the photon decay of the 18.15 MeV level of 8Be is found to be 5-8×10-6 for the best fit. Such a boson might be a good candidate for the relatively light U(1)d gauge boson, or the light mediator of the escluded WIMP dark matter scenario, or the dark photon, or the dark Z (Zd) suggested for explaining the muon anomalous magnetic moment. I am going to show the reliability of the data obtained, which will place such a particle into context with other experimental results, and discuss their implications.

The eighteenth meeting of the Radio MonteCarlo WG (http://www.lnf.infn.it/wg/sighad) will be held at LNF on Thursday and Friday, May 19th and 20th, 2016.

The quantum theory has been undergone innumerable experimental tests, all being in agreement with the predictions. However, the quantum theory lacks an explanation of very fundamental principles: such as the famous Pauli exclusion principle holding matter together or why we do not observe superposition of macroscopic objects or why time plays such a different role compared to position. In this talk I will review the basic theoretical concepts and their possibilities for testing.

Aim of the workshop: Looking for E.T.: The scientific hunt for extraterrestrial intelligence is now well into its fifth decade, and we still haven't uncovered a confirmed peep from any cosmic company. Could this mean that finding aliens, even if they exist, is a project for the ages – one that might take centuries or longer? New technologies for – and new approaches to – the Search forExtraterrestrial Intelligence (SETI) suggest that, despite the continued dearth of signals, there is good reason to expect that success might not be far off – that we might find evidence of sophisticated civilizations within a few decades. What would a contact tell us, and what would it mean to us, and to our descendants?

We examine the general features of the non-commutativity of the magnetization operator and Hamiltonian for small quantum spin clusters. The source of this non-commutativity can be a difference in the Landé g-factors for different spins in the cluster, XY-anisotropy in the exchange interaction and the presence of the Dzyaloshinskii-Moriya term in the direction different from the direction of the magnetic field. As a result, zero-temperature magnetization curves for small spin clusters mimic those for the macroscopic systems with the band(s) of magnetic excitations, i.e. for the given eigenstate of the spin cluster the corresponding magnetic moment can be an explicit function of the external magnetic field yielding the non-constant (non-plateau) form of the magnetization curve within the given eigenstate. In addition, the XY-anisotropy makes the saturated magnetization (the eigenstate when all spins in cluster are aligned along the magnetic field) inaccessible for finite magnetic field magnitude (asymptotical saturation). We demonstrate all these features on three examples: spin-1/2 dimer, mixed spin-(1/2,1) dimer, spin-1/2 ring trimer. We consider also the simplest Ising-Heisenberg chain, the Ising-XYZ diamond chain with four different g-factors. In the chain model the magnetization curve has a more complicated and non-trivial structure which that for clusters.