Search results for "waves"
showing 10 items of 1766 documents
Components of polarization-transfer to a bound proton in a deuteron measured by quasi-elastic electron scattering
2018
We report the first measurements of the transverse (Px and Py) and longitudinal (Pz) components of the polarization transfer to a bound proton in the deuteron via the H2(e→,e′p→) reaction, over a wide range of missing momentum. A precise determination of the electron beam polarization reduces the systematic uncertainties on the individual components to a level that enables a detailed comparison to a state-of-the-art calculation of the deuteron using free-proton electromagnetic form factors. We observe very good agreement between the measured and the calculated Px/Pz ratios, but deviations of the individual components. Our results cannot be explained by medium modified electromagnetic form f…
Muon capture in a general class of weak models.
1985
We study muon capture by /sup 12/C in a general class of weak models. There is always a parameter characteristic of the weak model that can be extracted in a nuclear-model-independent way from the average polarization P/sub av/, the longitudinal polarization P/sub L//sup N/ and the asymmetry ..cap alpha.. in the angular distribution of recoils. For a less general class of models the asymmetry ..cap alpha.. is unnecessary. Using the experimental values of P/sub L//sup N/ and P/sub av/ we get a lower bound for the mass of the right-handed gauge boson of the left-right-symmetric model, M/sub W//sub R/> or =2.5ML, in a nuclear-model-independent way. The dependence of this bound on the experimen…
Global polarization of Λ and Λ¯ hyperons in Pb-Pb collisions at sNN= 2.76 and 5.02 TeV
2020
The global polarization of the $\Lambda$ and $\overline\Lambda$ hyperons is measured for Pb-Pb collisions at $\sqrt{s_{\rm{NN}}}$ = 2.76 and 5.02 TeV recorded with the ALICE at the LHC. The results are reported differentially as a function of collision centrality and hyperon's transverse momentum ($p_{\rm{T}}$) for the range of centrality 5-50%, $0.5 < p_{\rm{T}} <5$ GeV/$c$, and rapidity $|y|<0.5$. The hyperon global polarization averaged for Pb-Pb collisions at $\sqrt{s_{\rm{NN}}}$ = 2.76 and 5.02 TeV is found to be consistent with zero, $\langle P_{\rm{H}}\rangle$ (%) $\approx$ 0.01 $\pm$ 0.06 (stat.) $\pm$ 0.03 (syst.) in the collision centrality range 15-50%, where the largest signal i…
Stabilizing and controlling domain walls and dark-ring cavity solitons.
2009
We demonstrate two alternative techniques for controlling and stabilizing domain walls (DW) in phase-sensitive, nonlinear optical resonators. The first of them uses input pumps with spatially modulated phase and can be applied also to dark-ring cavity solitons. An optical memory based on the latter is demonstrated. Here the physical mechanism of control relies on the advection caused to any feature by the phase gradients. The second technique uses a plane wave input pump with holes of null intensity across its transverse plane, which are able to capture DWs. Here the physical mechanism of control is of topological nature. When distributed as a regular array, these holes delimit spatial opti…
Generation of vector dark-soliton trains by induced modulational instability in a highly birefringent fiber
1999
International audience; We present a set of experimental observations that demonstrate the generation of vector trains of dark-soliton pulses in the orthogonal axes of a highly birefringent optical fiber. We generated dark-soliton trains with terahertz repetition rate in the normal group-velocity dispersion regime by inducing a polarization modulational instability by mixing two intense, orthogonal continuous laser beams. Numerical solutions of the propagation equations were used to optimize the emission of vector dark pulses at the fiber output.
Modulational Instability and Stimulated Raman Scattering in Normally Dispersive Highly Birefringent Fibers
2001
Abstract The nonlinear interaction of two laser beams in normally dispersive highly birefringent optical fibers leads to a large set of fascinating physical effects such as modulational instability (MI) and stimulated Raman scattering (SRS). These two nonlinear phenomena have a positive role as a mechanism for the generation of short optical pulses and represent a drawback in fiber-optics transmissions. Indeed, we will show that an induced process of modulational instability may be exploited for the generation of THz train of vector dark solitons. The technique of frequency-resolved optical gating is used to completely characterize the intensity and phase of the dark soliton trains. On the …
Dissipative Polarization Domain Walls in a Passive Coherently Driven Kerr Resonator.
2021
Using a passive, coherently driven nonlinear optical fiber ring resonator, we report the experimental realization of dissipative polarization domain walls. The domain walls arise through a symmetry breaking bifurcation and consist of temporally localized structures where the amplitudes of the two polarization modes of the resonator interchange, segregating domains of orthogonal polarization states. We show that dissipative polarization domain walls can persist in the resonator without changing shape. We also demonstrate on-demand excitation, as well as pinning of domain walls at specific positions for arbitrary long times. Our results could prove useful for the analog simulation of ubiquito…
A universal all-fiber omnipolarizer
2013
The all-optical control of light polarization is nowadays a fundamental issue which finds important applications in optical networks. In this field, the research has moved on the development of nonlinear methods of re-polarization of a partially coherent and initially depolarized light [1]. The main drawback of most of these devices is that they suffer from a large amount of output Relative-Intensity-Noise (RIN). However, a class of polarizers have been recently proposed which is based on the nonlinear interaction between two optical beams counter-propagating in a fiber [2]: in these devices the arbitrary state of polarization (SOP) of one of the two beams (signal) is attracted towards a sp…
Cross-phase modulational instability induced by Raman scattering in highly birefringent fiber
2013
We report experimental and theoretical studies of Raman-induced cross-phase modulational instabilities (XPMI) in a high-birefringence, normally dispersive optical fiber. Experimental results reveal that the Raman-Stokes wave, generated by a quasi-CW pump beam, interacts with the latter to create a novel type of XPMI sidebands. These sidebands are characterized by a narrow gain bandwidth. The sideband frequencies are well reproduced by a linear stability analysis as well as by full numerical solutions of the coupled generalized nonlinear Schrödinger equations.
Observation of modulational instability induced by velocity-matched cross-phase modulation in a normally dispersive bimodal fiber
2008
We demonstrate experimentally the existence of cross-phase-modulation-induced modulational instability in the absence of group-velocity mismatch between the interacting nonlinear dispersive waves. The experiment is performed by means of a normally dispersive isotropic bimodal fiber. The group-velocity mismatch between the fundamental and the first-order modes that constitute the two interacting waves is controlled by wavelength tuning. A strong power dependence of the modulational instability spectra is observed near the condition of group-velocity matching.