Tag Archives: Evento scientifico

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.

Aim of the workshop: Identifying what Dark Matter (DM) is, as well as its nature and properties, remains a major challenge for both theoretical and experimental astroparticle physics communities.  In the past decades, Weakly Interacting Massive Particle (WIMP) DM has been the most hunted candidate, with the result that nowadays WIMPs are cornered by large amounts of experimental data from Direct Detection, Indirect Detection and Collider Experiments.  If no WIMP signal is detected in the next few years, the possibility that this very appealing theoretical idea is not what Nature has chosen will become even more compelling and will boost theoretical studies and experimental searches for non-WIMP alternatives for DM. The aim of this 3-day meeting is to convene experts on alternatives to the WIMP paradigm to stimulate informal discussions on different possibilities  (dark photons, axion-like particles, Majorons, self-interacting dark sectors, just to mention a few). We plan to have only three or four talks each day and plenty of time to discuss implications of these DM scenarios, experimental search strategies, new theoretical proposals, and out-of-mainstream ideas. The general approach and format of the talks will be pedagogical and aimed at favoring extended discussions among all participants.  The audience will range from theorists who are expert on related topics to skillful experimentalists planning new non-WIMP detection experiments, as well as postdocs, graduate students and non-expert colleagues working in different areas. Speakers: J. Beacham (Ohio State U. & CERN) "Lost in a Dark Photon Wood: Searches for hidden light gauge bosons …

Aim of the workshop: 2016 LNF Spring School Frascati, May 9-13, 2016 Lectures are arranged in slots of 1.5 hours, for a total of 14 slots. Time is equally shared between Theoretical and Experimental topics/lectures. Theoretical topics (TL1: 3 lectures; TS2 and TS3: 2 lectures) are matched to related experimental topics (EL1: 3 lectures; ES2, ES3, 2 lectures). The School Program also includes: -Two Sessions of the Young Researchers Workshop: Monday 9th and Thursday 12th , 4.30-6.30pm. -Two Discussion Sessions: Tuesday 10th and Friday 13th , 4.30-6.00pm. -The Spring School Colloquium on Science and Technology: Tuesday 10th , 6.00-7.00pm. Topic No. of Lectures Speaker Theory: TL1: Dark Matter: models and signatures 3 Alejandro Ibarra (Munich, Tech. U.) TS2: Neutrinoless double beta decay: Theory 2 Werner Rodejohann (MPIK, Heidelberg) TS3: Signatures of new physics at LHC 2 Tilman Plehn (Heidelberg U., ITP) Experimental: EL1: Dark Matter: Experimental searches 3 Marc Schumann (AEC, Bern U.) ES2: Neutrinoless double beta decay experiments 2 Stefan Schönert (Munich, Tech. U.) ES3: Searches for new particles at the LHC 2 Oliver Buchmueller (Imp. Coll., London) Spring School Colloquium The SETI Project Explore, understand and explain the origin, nature and prevalence of life in the Universe (Tuesday 10th , 6.00pm) Seth Shostak Senior Astronomer and Director, Center for SETI research SCHEDULE AM PM 9.00-10.30 11.00-12.30 2.30-4.00 4.30-6.00 6.00-7.00 9/5 Mon TL1(DMth) EL1(DMexp) TS2(0n2bTh) Young Reserchers Workshop (4.30-6.30pm) 10/5 Tue TL1(DMth) EL1(DMexp) TS2(0n2bTh) Discussion Session Spring School Colloquium 11/5 Wed TL1(DMth) EL1(DMexp) Excursion 12/5 Thur TS3(MnXth) ES3(MnXEx) ES2(0n2bExp) …