Tag Archives: Evento scientifico

Aim of the workshop: The top-quark mass definition and determination is a major subject of debate in both theoretical and experimental communities. Different strategies to relate the measured and theoretical quantities have been envisaged. The aim of this  3-day meeting is to convene experts on this topic to stimulate an informal discussion on different aspects of the issue. We plan to have only three or four talks each day, and plenty of time to discuss  the connection between the experimentally reconstructed top mass relying on Monte Carlo generators and different theoretical mass definitions, including the most advanced strategies. Implications of the top-mass determination for physics beyond the standard model will be also covered. The general approach and format will be pedagogical, the audience ranging from top-quark physics experts to graduate students, and should favour extended discussion among participants. Confirmed Speakers:   Spyridon Argyropoulos        (DESY, Hamburg) Vincenzo Branchina            (Catania U. & INFN) Roberto Chierici                        (CNRS & IPNL, Lyon) Marina Cobal                             (Udine U. & INFN) Roberto Franceschini          (CERN, Geneva) Andrè Hoang                           (Vienna U.) Sandra Leone                     (INFN Pisa) Fabio Maltoni                     (Louvain U.) Sven-Olaf Moch                 (DESY, Hamburg) Michael Scherer                 (Heidelberg U.) Adrian Signer                     (PSI, Villigen)  

Quantum phase transitions play a key role in the understanding the phenomena of many-body systems, especially in anti-ferromagnetic magnetic plateaus. By means of variation mean-field-like treatment based on the Gibbs–Bogoliubov inequality, it is presented the frustrated magnetization plateau and thermal concurrence properties in spin-1/2 Ising–Heisenberg models on a triangulated Kagom´e lattice and a diamond chain. Using the transfer matrix method, an exact solution for the magnetization plateau and thermal entanglement of Ising-XYZ, Blume-Emery-Griffiths and Hubbard-Ising models on a diamond chain can be obtained. Partition function zeros of the spin-1/2 and spin-1 Ising-Heisenberg models on a diamond chain have been calculated using the transfer matrix method. The existence usual and triple Yang-Lee edge singularity exponents are shown.

I will present the theoretical motivations for dark photons, vector bosons arising from a new U(1) gauge symmetry that kinetically mix with the photon. Such particles appear in a number of extensions of the Standard Model and can also be motivated from a purely effective field theory perspective as they provide one of the few portals to a dark sector. Such states have also found motivation in their ability to help explain astrophysical and terrestrial anomalies, such as the discrepant anomalous magnetic moment of the muon, and may also mediate interactions to light dark matter.

The seventeenth meeting of the Radio MonteCarlo WG (http://www.lnf.infn.it/wg/sighad) will be held at LNF on Monday and Tuesday, April 20th and 21st, 2015.

Fermilab is developing an Advanced Accelerator R&D program centered at IOTA – the Integrable Optics Test Accelerator. This small and flexible ring will be used for proof-of-principle R&D of novel concepts towards future high intensity machines. Of particular interest are the nonlinear integrable optics and the space charge compensation. This talk reviews IOTA’s R&D program as supported by modeling and simulations, and presents the current status of the design and construction of the facility.

The main results, presented during the NEUTEL 2015 conference held in Venice in the week 2-6 of March 2015, will be shown and discussed in the seminar.

Nucleon-antinucleon quasi-bound states, or states coupled to these, were searched for in the days of LEAR at CERN. Nothing has been found, but broad states or states close to the threshold were not excluded. Recent indications of the existence of quasi-bound states in the N$\overline N$ system will be presented. The BES collaboration has discovered a broad enhancement close to the p$\overline p$ threshold in the S wave, isospin 0 state formed in radiative decays of J$\psi$. Another enhancement located about 50 MeV below the threshold was found in mesonic decays of J$\psi$. In terms of the Paris potential model these findings are likely to be due to the same state. Antiprotonic atomic data provide some support for this interpretation and indicate existence of another fairly narrow quasi-bound state in a P wave. Few clarifying experiments will be indicated.

The existence of nuclear states of $\bar K$ mesons and $\eta$ mesons has been expected for about thirty years. The physical interest of this field is related to a new mechanism of nuclear binding generated by excitations of the internal nucleon structure. Despite being short lived such states might offer a new and interesting nuclear spectroscopy. Despite long and extensive experimental search, the existence and properties of such states are still elusive. Some similarities and related questions of the $\eta$ and $\bar K$ cases will be shown. Possible origin of the experimental difficulties related to weak production rate and large widths of such states will be discussed. I will try to indicate usefulness of the recent AMADEUS/KLOE measurements.

The workshop is intended to discuss the potentials for the future of the LNF infrastructures in the fields of Material Science and Applied Physics

The leading long distance quantum corrections to the Newtonian potential imply tiny but observable effects in the restricted three-body problem of celestial mechanics, i.e., at the Lagrangian libration points of stable equilibrium the planetoid is not exactly at equal distance from the two bodies of large mass, but the Newtonian values of its coordinates are changed by a few millimeters in the Earth-Moon system. We show that such a theoretical calculation is governed by a couple of quintic algebraic equation, whereas coordinates of collinear Lagrangian points are given in terms of the solution of an algebraic equation of ninth degree. We also discuss the prospects to measure, with the help of laser ranging, the above departure from the equilateral triangle picture, which is a challenging task. On the other hand, a modern version of the planetoid is the solar sail, and much progress has been made, in recent years, on the displaced periodic orbits of solar sails at all libration points, both stable and unstable. By taking into account the quantum corrections to the Newtonian potential, displaced periodic orbits of the solar sail at libration points are again found to exist.