6062 research outputs found
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5D tomographic phase-space reconstruction of particle bunches
No full textWe propose a new beam diagnostics method to reconstruct the phase space of charged particle bunches in five dimensions, which consist of the horizontal and vertical positions and divergences as well as the time axis. This is achieved by combining a quadrupole-based transverse phase-space tomography with the adjustable streaking angle of a polarizable X-band transverse deflection structure. We demonstrate with detailed simulations that the method is able to reconstruct various complex phase-space distributions and that the quality of the reconstruction depends on the number of input projections. This method allows for the identification and visualization of previously unnoticed detailed features in the phase-space distribution and can thereby be used as a tool toward improving the performance of particle accelerators or performing more accurate simulation studies
Non-invertible symmetries along 4d RG flows
No full textWe explore novel examples of RG flows preserving a non-invertible self-duality symmetry. Our main focus is on = 1 quadratic superpotential deformations of 4d = 4 super-Yang-Mills theory with gauge algebra . A theory that can be obtained in this way is the so-called = 1 SYM where all adjoint chiral multiplets have a mass. Such IR theory exhibits a rich structure of vacua which we thoroughly examine. Our analysis elucidates the physics of spontaneous breaking of self-duality symmetry occurring in the degenerate gapped vacua. The construction can be generalized, taking as UV starting point a theory of class , to demonstrate how non-invertible self-duality symmetries exist in a variety of = 1 SCFTs. We finally apply this understanding to prove that the conifold theory has a non-invertible self-duality symmetry
Entanglement entropies of an interval for the massless scalar field in the presence of a boundary
No full textWe study the entanglement entropies of an interval for the massless compact boson either on the half line or on a finite segment, when either Dirichlet or Neumann boundary conditions are imposed. In these boundary conformal field theory models, the method of the branch point twist fields is employed to obtain analytic expressions for the two-point functions of twist operators. In the decompactification regime, these analytic predictions in the continuum are compared with the lattice numerical results in massless harmonic chains for the corresponding entanglement entropies, finding good agreement. The application of these analytic results in the context of quantum quenches is also discussed
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Get PDF<p>Rapporto di attivita' presentato alla riunione dei Presidenti CoPER 27 marzo 2024.</p>
Elastic Polarized-Proton Scattering off He Nuclei in the Glauber Model with Accounting for Spin Dependence
No full textDifferential cross sections for elastic He scattering at energies in the range of MeV and proton analyzing powers of this process are calculated on the basis of the Glauber diffraction model with allowance for the spin dependence of nucleon–nucleon amplitudes. Explicit expressions are obtained for the first time for all six invariant amplitudes of He scattering for the mechanisms of single, double, and triple incident-proton scattering off target nucleons. Good agreement with experimental data is found both for the cross sections and for spin observables in the forward hemisphere of scattering angles. Also, explicit expressions are obtained for He-scattering amplitudes violating time-reversal () invariance but preserving spatial parity (). These expressions can be used in testing invariance in this and other processes
Entropy-Area Law and Temperature of de Sitter Horizons from Modular Theory
No full textWe derive an entropy-area law for the future horizon of an observer in diamonds inside a static patch of de Sitter space-time, taking into account the back reaction of quantum matter fields. We prove the positivity and convexity of the relative entropy for coherent states using Tomita–Takesaki modular theory, from which the quantum null energy condition for diamonds follows. Furthermore, we show that the generalized entropy conjecture holds. Finally, we reveal that the local temperature that is measured by an observer at rest exhibits subleading quantum corrections with respect to the well known cosmological horizon temperature H/(2π)
A path integral formula of quantum gravity emergent from entangled local structures
No full textWe couple to group field theory (GFT) a scalar field that encodes the entanglement between manifold sites. The scalar field provides a relational clock that enables the derivation of the Hamiltonian of the system from the GFT action. Inspecting the Hamiltonian, we show that a theory of emergent gravity arises, and that this can be recast according to the Ashtekar's formulation of general relativity. The evolution of the GFT observables is regulated by the Shrödinger equation generated by the Hamiltonian. This is achieved by imposing a renormalization group (RG) flow that corresponds to a simplified Ricci flow. As a consequence of the quantization procedure, the Hamiltonian is recovered to be non-Hermitian, and can be related to the complex action formalism, in which the initial conditions and the related future evolution of the systems are dictated by the imaginary part of the action
All Two-Loop Feynman Integrals for Five-Point One-Mass Scattering
No full textWe compute the complete set of two-loop master integrals for the scattering of four massless particles and a massive one. Our results are ready for phenomenological applications, removing a major obstacle to the computation of complete next-to-next-to-leading order QCD corrections to processes such as the production of a H/Z/W boson in association with two jets at the LHC. Furthermore, they open the door to new investigations into the structure of quantum-field theories and provide precious analytic data for studying the mathematical properties of Feynman integrals
Quantum computation of thermal averages for a non-Abelian <math display="inline"><msub><mi>D</mi><mn>4</mn></msub></math> lattice gauge theory via quantum Metropolis sampling
No full textIn this paper, we show the application of the quantum Metropolis sampling (QMS) algorithm to a toy gauge theory with discrete non-Abelian gauge group D4 in (2+1)-dimensions, discussing in general how some components of hybrid quantum-classical algorithms should be adapted in the case of gauge theories. In particular, we discuss the construction of random unitary operators which preserve gauge invariance and act transitively on the physical Hilbert space, constituting an ergodic set of quantum Metropolis moves between gauge invariant eigenspaces, and introduce a protocol for gauge invariant measurements. Furthermore, we show how a finite resolution in the energy measurements distorts the energy and plaquette distribution measured via QMS, and propose a heuristic model that takes into account part of the deviations between numerical results and exact analytical results, whose discrepancy tends to vanish by increasing the number of qubits used for the energy measurements
Dark radiation from the primordial thermal bath in momentum space
No full textMotivated by the stunning projections for future CMB surveys, we evaluate the amount of dark radiation produced in the early Universe by two-body decays or binary scatterings with thermal bath particles via a rigorous analysis in momentum space. We track the evolution of the dark radiation phase space distribution, and we use the asymptotic solution to evaluate the amount of additional relativistic energy density parameterized in terms of an effective number of additional neutrino species ΔN. Our approach allows for studying light particles that never reach equilibrium across cosmic history, and to scrutinize the physics of the decoupling when they thermalize instead. We incorporate quantum statistical effects for all the particles involved in the production processes, and we account for the energy exchanged between the visible and invisible sectors. Non-instantaneous decoupling is responsible for spectral distortions in the final distributions, and we quantify how they translate into the corresponding value for ΔN. Finally, we undertake a comprehensive comparison between our exact results and approximated methods commonly employed in the existing literature. Remarkably, we find that the difference can be larger than the experimental sensitivity of future observations, justifying the need for a rigorous analysis in momentum space