Tag Archives: Evento scientifico

High-precision measurements of flavour-changing processes are sensitive to the virtual effects of particles at energies beyond the reach of current colliders; thus, any New-Physics addressing the hierarchy problem of the electroweak scale must have a non trivial structure in flavour space to avoid all the stringent flavour constraints. In fact, although no new heavy particles have been identified in the high-energy frontier yet, there are tantalizing tensions with the SM in B-meson decays measured at the LHCb and B factories. The first type of anomalies appear in observables of the FCNC rare b→s ll decays, like in the angular distributions of B→K*μ μ, or in the ratio RK = Γ(B→K μ μ) / Γ(B→K e e) . These are currently in 4σ tension with the SM, putatively corresponding to the tree-level exchange of a neutral particle with mass Λ ~ 10 TeV selectively coupling to muons. The second type of anomalies appear in the CC b→ c τ ν transitions which have been measured through the ratios RD(*) = Γ(B→D(*) τ ν)/ Γ(B→D(*) l ν), where l is the muon or the electron. The average of the measurements is enhanced with respect to the SM and it would correspond to the tree-level exchange of a charged particle with mass Λ ~ 1 TeV and coupled selectively to τ leptons. In this talk I will review these decays, discussing the extent up to which the SM predictions are understood and the type of new physics one would need to explain the …

The lecture is devoted to a quantum mechanical consideration of the transmission of positrons of a kinetic energy of 1 MeV through very short (11, 9) single-wall chiral carbon nanotubes. The nanotube lengths are between 50 and 320 nm. The transmission process is determined by the rainbow effects. The interaction potential of a positron and the nanotube is deduced from the Molière’s interaction potential of the positron and a nanotube atom using the continuum approximation. The time-dependent Schrödinger equation is solved numerically, and the spatial and angular distributions of transmitted positrons are calculated. The initial positron beam is assumed to be an ensemble of non-interacting Gaussian wave packets. The spatial and angular distributions are generated using a computer simulation method. The examination is focused on the spatial and angular primary rainbows. It begins with an analysis of the corresponding classical rainbows, and continues with a detailed investigation of the amplitudes and phases of the wave functions of transmitted positrons. These analyses enable one to identify the principal and supernumerary primary rainbows appearing in the spatial and angular distributions. They also result in a detailed explanation of the way of their generation, which includes the effects of wrinkling of each wave packet during its deflection from the nanotube wall, and of its concentration just before a virtual barrier lying close to the corresponding classical rainbow. The wrinkling of the wave packets occurs due to their internal focusing. In addition, the wave packets wrinkle in a mutually coordinated way.

Recent theoretical developments highlight a set of shared principles underpinning macroscopic quantum coherence in high temperature superconducting (HTSC) materials and the emergence of long-range order and macroscopic quantum coherence phenomena such as photosynthesis in biological structures. Preliminary investigations suggest that the emergence of functionality and structure in these systems is driven by dissipative processes, which lead to fractal assembly and a fractal network of charges (with associated quantum potentials) at the molecular scale. At critical levels of charge density and fractal dimension, a percolation threshold is reached where individual quantum potentials merge to form an infinitely interconnected `charged-induced’ macroscopic quantum potential (MQP), which can be viewed as a macroscopic path integral. The process by which a MQP acts as a structuring force (in competition with environmental perturbation) dictating the emergence of structure and function in biological and inorganic systems will be described within the context of a new set of macroscopic quantum mechanics processes. Specific issues to be highlighted include the emergence of different phases (coherent electron pairs, Charge Density Waves and Spin Density Waves) observed in complex HTSC materials. The macroscopic quantum processes that underpin these different phenomena will be compared and contrasted with standard quantum mechanics to highlight the extent of commonality (and key differences) between the two quantum systems. Within the context of these new theoretical developments we consider a new experimental approach to the development of inorganic structures and macroscopic coherent systems, analogous to those emerging through biological processes. It is anticipated that this work will …

The CMS-TOTEM Precision Proton Spectrometer (CT-PPS) is an approved project to add tracking and timing information at approximately ±210~m from the interaction point around the CMS detector. It is designed to operate at high luminosity with up to 50 interactions per 25~ns bunch crossing to perform measurements of e.g. the quartic gauge couplings and search for rare exclusive processes. During 2016, CT-PPS took data in normal high-luminosity proton-proton LHC collisions. In the coming years, high radiation doses and large multiple-vertex interactions will represent difficult challenges that resemble those of the high-luminosity LHC program. A coordinated effort of detector upgrades with the goal of reaching the physics goals while mitigating the degradation effects is under way. The ongoing program, including the status and the planned upgrade projects for the tracking and timing detectors are discussed.

We associate with each simple Lie algebra a system of second-order differential equations invariant under a non-compact real form of the corresponding Lie group. In the limit of a contraction to a Schrodinger algebra, these equations reduce to a system of ordinary harmonic oscillators. We provide two clarifying examples of such deformed oscillators: one system invariant under SO(2,3) transformations, and another system featuring G2(2) symmetry. The construction of invariant actions requires adding semi-dynamical degrees of freedom; we illustrate the algorithm with the two examples mentioned.

The QCD axion is probably the most robust solution to the strong CP problem and a natural dark matter candidate. While its properties, such as the mass and the couplings, are mostly determined by non-perturbative QCD effects I will present recent computations demonstrating that they can be reliably extracted with percent accuracy, which is important for the theory interpretation of experimental results. I will also discuss some recent lattice QCD results highlighting a departure from the usual instanton estimates and potentially changing the prediction for the axion relic abundance substantially. In this seminar I will discuss what changes to analysis strategy and detector setup will be necessary to definitively discover or exclude the experimentally-elusive pure-higgsino thermal relic at the FCC, thus closing the window on neutralino dark matter.

An Electron Ion-Collider (EIC) has been highlighted as the highest priority for new construction in the DoE Office of Nuclear Physics. This is a very challenging accelerator that aims to achieve high luminosity and polarization over a large center of mass span. Alternative designs are pursued at Jefferson Laboratory (JLAB) and Brookhaven National Laboratory (BNL) each capitalizing on the existing CEBAF and RHIC facilities respectively. I will overview the design options at JLAB and BNL, the accelerator R&D necessary to validate the designs and will explore areas of potential synergy and collaboration.

Well motivated extensions of the Standard Model of particle physics predict the existence of light particles such as axions or axion-like particles (ALPS). These particles may constitute the long sought dark matter, solve the strong-CP problem and explain astrophysical anomalies. Contrary to the WIMPs (weakly interacting massive particles), WISPs (weakly interacting slim particles) are hardly observable at large colliders and new experiments involving a wide range of different technologies are needed. Present experiments aim at observing WISPs as a dark matter constituent, as radiation emitted from astronomical objects, or as radiation produced in the laboratory. In all the cases present and future experiments push the technology needed for detection and production of these particles to the state of the art or beyond. During the workshop we will review the status of ongoing and foreseen experiments, discuss of possible new physics at low energy scale that can be probed in such experiments and examine present and future developments of related key technologies.  

Ultrathin superconductors of different materials are becoming a powerful platform to find mechanisms for enhancement of superconductivity, exploiting shape resonances in different superconducting properties. Since 2004, the observation of shape resonances in superconducting nanofilms of Pb and first evidences of shape resonances in the superconducting critical temperature in metallic nanowires of Sn and Al [1–2] clearly established the importance of the interplay between quantum size effects, leading to multiple bands, and superconductivity, when the lateral dimensions of the system are reduced to the order of the interparticle distance or the pair correlation length. Moreover, superconductivity in iron-based, magnesium diborides, and other high-Tc superconductors has a strong multi-band and multi-gap character [3,4]. Recent experiments support the possibility for a BCS-BEC crossover induced by the proximity of the chemical potential to the band edge of one of the bands, with evidences for Lifshitz transitions associated with changes in the Fermi surface topology [5, 6]. Here we present the simplest theoretical model which accounts for superconducting shape resonances and the BCS-BEC crossover in a multi-band / multi-gap superconductor, considering tunable interactions and nanostructured geometries. When the gap is of the order of the local chemical potential, superconductivity is in the crossover regime of the BCS-BEC crossover and the Fermi surface of the small band is completely smeared by the gap opening. In this situation, small and large Cooper pairs coexist in the total condensate, which is the optimal condition for high-Tc or even for room temperature superconductivity [7,8]. As a realizable example of …