Search results for "Retrieval"
showing 10 items of 1176 documents
Re-weighting at the LHC: the p–Pb data impact
2016
Abstract In this work we present selected results of a comprehensive analysis of the medium modifications in proton-lead LHC Run I data, and discuss the implications on different sets of nuclear parton densities. We find that the nuclear environment has a non-negligible relevance on the experimental results. We incorporate the information from Run I into the current nuclear densities and provide novel sets of nPDFs that will be useful for future predictions.
Virtual Compton scattering off the nucleon at low energies
1996
We investigate the low-energy behavior of the four-point Green's function $\Gamma^{\mu\nu}$ describing virtual Compton scattering off the nucleon. Using Lorentz invariance, gauge invariance, and crossing symmetry, we derive the leading terms of an expansion of the operator in the four-momenta $q$ and $q'$ of the initial and final photon, respectively. The model-independent result is expressed in terms of the electromagnetic form factors of the free nucleon, i.e., on-shell information which one obtains from electron-nucleon scattering experiments. Model-dependent terms appear in the operator at $O(q_\alpha q'_\beta)$, whereas the orders $O(q_\alpha q_\beta)$ and $O(q'_\alpha q'_\beta)$ are c…
Neutrino propagation in magnetized media
1999
Abstract After a short presentation of the general techniques used to determine neutrino potentials in a magnetized medium I will discuss some applications to MSW resonant oscillations. I will also consider the relevance of our results for the pulsar velocity problem.
Onset of nuclear vaporization inAu197+197Au collisions
1993
Multifragmentation has been measured for [sup 197]Au+[sup 197]Au collisions at [ital E]/[ital A]=100, 250, and 400 MeV. The mean fragment multiplicity increases monotonically with the charged particle multiplicity at [ital E]/[ital A]=100 MeV, but decreases for central collisions with incident energy, consistent with the onset of nuclear vaporization. Molecular dynamics calculations follow some trends but underpredict the observed fragment multiplicities. Including the statistical decay of excited residues improves the agreement for peripheral collisions but worsens it for central collisions.
Measurement of magnetic monopole transition in electron scattering fromO16as direct test of dispersive effects
1991
For the first time an experiment has been performed to measure a magnetic monopole transition in inelastic electron scattering. In {sup 16}O the 0{sup +}{r arrow}0{sup {minus}} transition to the level at {ital E}{sub {ital x}}=10.957 MeV has been observed with a cross section of {ital d}{sigma}/{ital d}{Omega}=(5.4{plus minus}3.8){times}10{sup {minus}37} cm{sup {minus}2}/sr. Measurement of this transition is a direct signature of two-step contributions in electron scattering. Our measurement is in good agreement with the strength calculated for this transition.
Unambiguous phase retrieval in fiber-based interferometers
2020
A scheme for fiber interferometers, exploiting frequency-multiplexing in orthogonal fiber polarization modes, enables unambiguous phase retrieval. This allows for arbitrary phase tuning, providing a precise tool for time-bin qubit manipulation.
Towards a combined analysis of inclusive/exclusive electroproduction
2019
In view of the major advances achieved by the CLAS experiments in studying the N* electroexcitation amplitudes, as well as further extension of these studies in the experiments with CLAS12, we present an approach for the evaluation of the resonant contributions to inclusive electron scattering off protons. For the first time, the resonant contributions are determined from the experimental results on N* electrocouplings available from the data analyses of exclusive meson electroproduction off protons. This is a useful benchmark for future endeavours on understanding the transition region between low and high-energy regions, strongly related to tests on quark-hadron duality.
Light-by-light forward scattering amplitudes in Lattice QCD
2017
We present our preliminary results on the calculation of hadronic light-by-light forward scattering amplitudes using vector four-point correlation functions computed on the lattice. Using a dispersive approach, forward scattering amplitudes can be described by $\gamma^* \gamma^* \to$ hadrons fusion cross sections and then compared with phenomenology. We show that only a few states are needed to reproduce our data. In particular, the sum rules considered in this study imply relations between meson$-\gamma\gamma$ couplings and provide valuable information about individual form factors which are often used to estimate the meson-pole contributions to the hadronic light-by-light contribution to …
Universality-Breaking Effects in Leptonic Z Decays
1993
We analyze the possibility of universality violation in diagonal leptonic decays of the $Z$ boson, in the context of interfamily "see-saw" models. In a minimal extension of the Standard Model with right-handed neutrino fields, we find that universality-breaking effects increase quadratically with the heavy Majorana neutrino mass and may be observed in the running $LEP$ experiments.
Dimension of the isometry group in three-dimensional Riemannian spaces
2021
The necessary and sufficient conditions for a three-dimensional Riemannian metric to admit a group of isometries of dimension $r$ acting on s-dimensional orbits are obtained. These conditions are Intrinsic, Deductive, Explicit and ALgorithmic and they offer an IDEAL labeling that improves previously known invariant studies.