Tag Archives: Evento scientifico

Semileptonic decays provide an excellent environment for testing the Standard Model. Tests of lepton flavour universality using b->clnu decays have shown hints of new physics. In this seminar, an overview of the status of these measurements is given, including the impact of radiative corrections on these types of measurement. Also CKM matrix elements, and in particular |Vcb|, can be measured using semileptonic B decays. There is a long-standing disagreement between values of |Vcb| measured inclusively or exclusively. The exclusive determination relies on the parametrisation of the form factors of the decay.  Measurements using Bs mesons instead of B mesons can shed a new light on lepton flavour universality,  |Vcb| and form factors. They suffer from less backgrounds from excited decays and are easier to compute on a lattice. In this seminar I will present a new measurement of |Vcb| using Bs decays, as well  as measurements of Bs->Ds(*)munu form factors, performed by the LHCb experiment. Future prospects for measurements of Vcb, R(Ds) and R(Ds*) are also discussed.

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.

ALICE (A Large Ion Collider Experiment) is the CERN LHC experiment optimized for the study of the strongly interacting matter produced in heavy-ion collisions and for the characterization of the quark-gluon plasma (QGP). ALICE has collected precision data at different energies for pp, p-Pb, Pb-Pb and Xe-Xe collisions: this unique set of data allows us to investigate bulk particle production for very different systems and compare them at similar multiplicities. In particular, light flavour particles, containing only u, d and s valence quarks, are the most copiusly produced and so they play a central role in the characterization of the bulk properties of the QGP, carrying essential information about the produced medium and reaction dynamics. Part of this information is carried by the inclusive and identified transverse momentum distributions of light charged particles, measured over a wide pT range thanks to the excellent tracking and particle-identification capabilities of the ALICE detector. Such distributions show that at low to intermediate pT charged particle production is governed by the collective expansion of the system. The chemical and kinetic freeze-out parameters of the system are extracted via statistical-thermal and combined blast-wave fits to the data in heavy-ion collisions and are compared to results obtained in pp and p-Pb collisions at similar multiplicities. At high pT, typically above 5 GeV/c, a suppression of hadronic production, due to medium effects such as parton energy loss, can be observed. These effects can be investigated by calculating the nuclear modification factor, defined as the ratio between the pT spectrum measured in nucleus-nucleus collisions and a reference spectrum in pp collisions scaled by the number of binary nucleon-nucleon collisions. In this talk, we review the most recent ALICE results on the production of pions, …

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.

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.

The need of a fs-scale pulsed, MHz-class repetition rate, X-ray source for time-resolved fine analysis of matter (spectroscopy and photon scattering) in the linear response regime is addressed by the conceptual design of a facility called MariX, outperforming current X-ray sources based on FELs or Synchrotrons for the declared scope. MariX is based on the original design of a two-pass two-way superconducting linear electron accelerator, equipped with an arc compressor, to be operated in CW mode with up to 1MHz repetition rate. MariX provides FEL emission in the range 0.2-8 keV with up to 10^10 photons per pulse and up to 10^16 photons/s using a 1.5 GeV Linac, but delivering to the FEL undulators up to 3.8 GeV electrons. The accelerator complex includes an early stage that supports an advanced inverse Compton source of very high-flux hard X-rays (up to 10^13 monochromatic X-ray photon beams), of energies up to 180 keV, that are well adapted for large area advanced radiological imaging. Such a complex enables a broad science program and will serve a multidisciplinary user community, covering fundamental science of matter and application to life sciences, including health at preclinical and clinical level. MariX C.D.R. has been recently published on its dedicated web site: www.marix.eu.

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.  

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.

This informal meeting is the second of the Rome physics encounter series. It aims at bringing together young speakers working or collaborating with the research groups in the Rome area. In the spirit of workshops and conferences at LNF, talks will be presented in a pedagogical way and plenty of time is scheduled to allow discussions among participants. The encounters will be synchronised with a selected LNF General Seminar, held in the afternoon at 2.30pm. The lunch is offered to all registered participant at the LNF canteen.