Gluon and Wilson loop TMDs for hadrons of spin ≤ 1

In this paper we consider the parametrizations of gluon transverse momentum dependent (TMD) correlators in terms of TMD parton distribution functions (PDFs). These functions, referred to as TMDs, are defined as the Fourier transforms of hadronic matrix elements of nonlocal combinations of gluon fields. The nonlocality is bridged by gauge links, which have characteristic paths (future or past pointing), giving rise to a process dependence that breaks universality. For gluons, the specific correlator with one future and one past pointing gauge link is, in the limit of small x, related to a correlator of a single Wilson loop. We present the parametrization of Wilson loop correlators in terms of Wilson loop TMDs and discuss the relation between these functions and the small-x ‘dipole’ gluon TMDs. This analysis shows which gluon TMDs are leading or suppressed in the small-x limit. We discuss hadronic targets that are unpolarized, vector polarized (relevant for spin-1/2 and spin-1 hadrons), and tensor polarized (relevant for spin-1 hadrons). The latter are of interest for studies with a future Electron-Ion Collider with polarized deuterons

The gluon structure of hadrons and nuclei from lattice QCD

I discuss recent lattice QCD studies of the gluon structure of hadrons and light nuclei. After very briefly highlighting new determinations of the gluon contributions to the nucleon’s momentum and spin, presented by several collaborations over the last year, I describe first calculations of gluon generalised form factors. The generalised transversity gluon distributions are of particular interest since they are purely gluonic; they do not mix with quark distributions at leading twist. In light nuclei they moreover provide a clean signature of non-nucleonic gluon degrees of freedom, and I present the first evidence for such effects, based on lattice QCD calculations. The planned Electron-Ion Collider, designed to access gluon structure quantities, will have the capability to test this prediction, and measure a range of gluon observables including generalised gluon distributions and transverse momentum dependent gluon distributions, within the next decade

Standard Model Physics at the HL-LHC and HE-LHC

The successful operation of the Large Hadron Collider (LHC) and the excellent performance of the ATLAS, CMS, LHCb and ALICE detectors in Run-1 and Run-2 with $pp$ collisions at center-of-mass energies of 7, 8 and 13 TeV as well as the giant leap in precision calculations and modeling of fundamental interactions at hadron colliders have allowed an extraordinary breadth of physics studies including precision measurements of a variety physics processes. The LHC results have so far confirmed the validity of the Standard Model of particle physics up to unprecedented energy scales and with great precision in the sectors of strong and electroweak interactions as well as flavour physics, for instance in top quark physics. The upgrade of the LHC to a High Luminosity phase (HL-LHC) at 14 TeV center-of-mass energy with 3 ab$^{-1}$ of integrated luminosity will probe the Standard Model with even greater precision and will extend the sensitivity to possible anomalies in the Standard Model, thanks to a ten-fold larger data set, upgraded detectors and expected improvements in the theoretical understanding. This document summarises the physics reach of the HL-LHC in the realm of strong and electroweak interactions and top quark physics, and provides a glimpse of the potential of a possible further upgrade of the LHC to a 27 TeV $pp$ collider, the High-Energy LHC (HE-LHC), assumed to accumulate an integrated luminosity of 15 ab$^{-1}$

Design and Fabrication of a Pillar-based Piezoelectric Microphone exploiting 3D-Printing Technology

This letter presents a 3-D-printed piezoelectric microphone with enhanced voltage sensitivity. The sensitivity is improved by a combination of a single-pillar mechanical design and a specific polyvinylidene fluoride (PVDF)-film electrode patterning. The moving part of the mechanical structure and the chassis are 3D-printed as a single unit and trimmed by laser cutting, allowing for a simple fabrication of the device. The measured sensitivity of 1 mV/Pa (\ub16 dB) in the bandwidth 500\u20132500 Hz agrees with simulations, showing an improvement over similar pillar-based piezoelectric sensor solutions. The sensitivity performance is shown to be comparable to existing microphones with different technologies. The microphone is also characterized by excellent linearity within the measurable range. 3D-printing technique can thus be adopted for the manufacturing of low cost and highly customizable microphone sensors

REALIZING COMPUTATION

The aim of this paper is to address the question: when does a physical system realize (implement) a certain computation? The most developed account that answers this question is Piccinini’s mechanistic account. Our strategy is to start from Piccinini’s reflections, emphasizing different aspects of the problem of realization and thus proposing a novel account. Our idea is to propose a new definition of realization that makes the original question more tractable and easier to scrutinize. We show that our definition has some advantages when dealing with classical objections to accounts of computation in physical systems. The paper is structured in four parts: after the introduction, the first part will introduce mapping accounts of implementation discussing some of their problematic aspects; the second part will present and clarify some prerequisite notions for a definition of realization; the third part will introduce our definition – it will turn out that our definition will identify a specific kind of strategy that Piccinini (2015a; 2015b) calls nomological mapping account; the fourth and final part will be dedicated to analysing the advantages of our definition. Concluding remarks follow