iten
Home » Evento

Tag Archives: Evento scientifico

Graphene Wormholes: From General Relativity to Nano-technologies

We propose a model describing the evolution of free electron current density in graphene giving rise to bidimensional wormhole solutions. Based on analogue concepts of General Relativity, we perform the analysis using the difference between curvatures of parallel and antiparallel spins. In such a framework, effective “gravitons” emerges in the form of gauge fields exchanged between electrons. In a plain grapheme system, the curvatures produced by both kinds of spins neutralize each other giving rise to no conduction. However, in the presence of geometrical defects of the graphene sheets, the inequality between curvatures leads to the emergence of current densities and conductivity in a wormhole solution. Depending on the type of defects, the resulting current density can be negative or positive. Possible applications are discussed.

Scopri di più »

The charm and beauty of the Little Bang

In relativistic heavy-ion collisions a “Little-Bang” is produced, in which the matter for a few fm/c experiences very similar (but not equal) conditions to the one occurred in the early universe, about one millionth of a second after the Big Bang. In particular one expects to produce a fireball of deconfined QCD matter in which the active degrees of freedom are quarks and gluons rather than hadrons. If this fireball lives for such a short amount of time, which are the experimental signatures of the onset of deconfinement and how can one extract information about its properties from the experimental data? In this connection I will show how heavy-flavour particles arising from the hadronization of charm and beauty quarks play a major role.

Scopri di più »

From kaonic atoms to strangeness in neutron stars

An updated review is presented of the theory of low-energy antikaon and hyperon interactions with nucleons and nuclear systems. Applications include kaonic hydrogen, recent calculations of kaonic deuterium and comparisons with K-p correlation functions from ALICE at LHC. This is followed by a discussion of the possible role played by kaons and hyperons in dense baryonic matter, with special emphasis on constraints provided by the existence of two-solar-mass neutron stars and garvitational wave signals of neutron star mergers.

Scopri di più »

The ILC project – its physics and status

The international Linear Collider (ILC) is an electron-positron collider whose initial goal is to make precision measurements on the Higgs boson. Such measurements are expected to elucidate the shortcomings of the Standard Model of elementary particles and guide us to the new physics that governs the universe. Being a linear collider, It also has potential to upgrade its collision energy without sacrificing the investment up to that point.  In this talk, we review the scientific case of the ILC and describe its political status.

Scopri di più »

Quantum Optical Control of Levitated Solids: a novel probe for the gravity-quantum interface

The increasing level of control over motional quantum states of massive, solid-state mechanical devices opens the door to an hitherto unexplored parameter regime of macroscopic quantum physics. I will report on our recent progress towards controlling levitated solids in the quantum regime. I will discuss the prospects of using these systems for fundamental tests of physics, including the interface between quantum and gravitational physics.

Scopri di più »

Some new ideas in Leptogenesis and Dark Matter studies

Type-1 seesaw is the simplest extension of the Standard Model (SM) that explains light neutrino masses and baryon asymmetry of the universe (BAU) via leptogenesis. In the first part of this talk, I shall discuss how different seesaw models can be visualised graphically and how a fine-tuning in the seesaw formula can be related to a Lorentz boost in the flavour space. I shall discuss a new parametrization of standard Casas-Ibarra orthogonal matrix and show how this new parametrisation is more useful in leptogenesis studies, particularly in SO (10) models. In the second part, I will show that an additional right handed (RH) neutrino could be a DM candidate in the two RH neutrino seesaw model if one considers the new one interacts with the other two with an effective dimension 5 operator induced by SM Higgs. This operator creates a temperature dependent matter potential and therefore the DM (the new RH neutrino) is produced from RH neutrino oscillation due to MSW-like matter effect even if the scale of new physics is post-Planckian. The operator responsible for DM production also causes the DM decay (to light neutrinos) and makes the scenario testable at neutrino telescopes such as IceCube.

Scopri di più »

B-decay discrepancies: Where we stand after Moriond 2019

A whole set of B-decay data display persistent deviations with respect to the Standard Model (SM). Specifically, data hint at new effects in semi-leptonic interactions involving the b -> s and b -> c currents. Interestingly, the pattern of discrepancies after the recent Run-2 updates suggest well-defined effective-field theory (EFT) scenarios where the two sets of discrepancies, b -> s and b -> c, are related. In turn, such EFT picture finds a quantitative realization within well-defined UV-complete scenarios. I will provide a review of the whole subject, from data to the EFT picture to UV models.  

Scopri di più »

Global fits to b → cτν transitions

We perform a general model-independent analysis of b → cτντ transitions, including measurements of RD , RD∗ , their q2 differential distributions, the recently measured longitudinal D∗ polarization FD∗, and constraints from the Bc → τντ lifetime, each L of which has significant impact on the fit. A global fit to a general set of Wilson coefficients of an effective low-energy Hamiltonian is presented, the solutions of which are interpreted in terms of hypothetical new-physics mediators. From the obtained results we predict selected b → cτντ observables, such as the baryonic transition Λb → Λcτντ, the ratio RJ/ψ, the forward-backward asymmetries AD(∗), FB the τ polarization asymmetries PD(∗) , and the longitudinal D∗ polarization fraction τ F D∗ . The latter shows presently a slight tension with any new-physics model, such L that an improved measurement could have an important impact.  

Scopri di più »

Daya Bay and JUNO Reactor Neutrino Experiments in China

Neutrino mass, shown by neutrino mixing and oscillation, is currently the only sign of new physics beyond the Standard Model (SM) of particle physics. In the completion of the three neutrino mixing angles, the Daya Bay Reactor Neutrino Experiment played a crucial and pioneering role in the measurement of the lastly known mixing angle θ13. Despite all the progresses in the last two decades in neutrino physics, we still only know the two mass-squared differences about neutrino mass, neither their absolute values nor the mass ordering. Due to the challenges in measuring the absolute masses, the neutrino mass ordering (NMO) is very likely to be the first experimental handle we could have on physics related to neutrino mass. With the success of the Daya Bay experiment and its contemporaries, it is now possible to resolve NMO using reactor neutrinos. Jiangmen Underground Neutrino Observatory (JUNO) was proposed to take the advantage of this principle to resolve NMO. In this talk, we will give a general review on neutrino physics, the discovery of neutrino oscillation and its recent experimental progresses, with the focus on Daya Bay and JUNO in China.

Scopri di più »