Search results for "Nucleon"
showing 10 items of 1041 documents
Final COMPASS results on the deuteron spin-dependent structure functiong1dand the Bjorken sum rule
2017
Final results are presented from the inclusive measurement of deep-inelastic polarised-muon scattering on longitudinally polarised deuterons using a 6 LiD target. The data were taken at 160 GeV beam energy and the results are shown for the kinematic range 1(GeV/c)2 4GeV/c2 in the mass of the hadronic final state. The deuteron double-spin asymmetry A1d and the deuteron longitudinal-spin structure function g1d are presented in bins of x and Q2 . Towards lowest accessible values of x , g1d decreases and becomes consistent with zero within uncertainties. The presented final g1d values together with the recently published final g1p values of COMPASS are used to again evaluate the Bjorken sum rul…
Spin structures of the pion and nucleon
2012
We present recent studies on the transverse spin densities of the pion and nucleon within the framework of the chiral quark-(soliton) model, based on the calculation of the electromagnetic and tensor form factors of the pion and the nucleon. The results for the transverse spin densities of the quark inside a pion are in good agreement with the recent lattice data, while those of the nucleon show similar features to the lattice results. We also present the first results of the transverse spin densities of the strange quark inside a nucleon.
Barkas effect with use of antiprotons and protons.
1989
The difference in the range of protons and antiprotons in matter, an example of the Barkas effect, is observed in a simple time-of-flight apparatus. The ranges of 5.9-MeV antiprotons and protons differ by about 6% in a degrader made predominantly of aluminum.
Anisotropic Flow of Charged Particles in Pb-Pb Collisions atsNN=5.02 TeV
2016
We report the first results of elliptic (v2), triangular (v3), and quadrangular (v4) flow of charged particles in Pb-Pb collisions at a center-of-mass energy per nucleon pair of √sNN=5.02 TeV with the ALICE detector at the CERN Large Hadron Collider. The measurements are performed in the central pseudorapidity region |η|<0.8 and for the transverse momentum range 0.2<pT<5 GeV/c. The anisotropic flow is measured using two-particle correlations with a pseudorapidity gap greater than one unit and with the multiparticle cumulant method. Compared to results from Pb-Pb collisions at √sNN=2.76 TeV, the anisotropic flow coefficients v2, v3, and v4 are found to increase by (3.0±0.6)%, (4.3±1.4)%, …
Investigations of Anisotropic Flow Using Multiparticle Azimuthal Correlations in pp , p−Pb , Xe-Xe, and Pb-Pb Collisions at the LHC
2019
Measurements of anisotropic flow coefficients (vn) and their cross-correlations using two- and multiparticle cumulant methods are reported in collisions of pp at √s=13 TeV, p−Pb at a center-of-mass energy per nucleon pair √sNN=5.02 TeV, Xe-Xe at √sNN=5.44 TeV, and Pb-Pb at √sNN=5.02 TeV recorded with the ALICE detector. The multiplicity dependence of vn is studied in a very wide range from 20 to 3000 particles produced in the midrapidity region |η| v3>v4 is found in pp and p−Pb collisions, similar to that seen in large collision systems, while a weak v2 multiplicity dependence is observed relative to nucleus-nucleus collisions in the same multiplicity range. Using a novel subevent method, v…
PRODUCTION OF Θ+ HYPERNUCLEI WITH THE (K+, π+) REACTION
2005
Abstract We present results on the production of bound states of Θ + in nuclei using the ( K + , π + ) reaction. By taking into account the states obtained within a wide range of strength of the Θ + nucleus optical potential, plus the possibility to replace different nucleons of the nucleus, we obtain an excitation spectra with clearly differentiated peaks. The magnitude of the calculated cross sections is well within reachable range.
Spectroscopy ofHo144using recoil-isomer tagging
2010
Excited states in the proton-unbound odd-odd nucleus $^{144}\mathrm{Ho}$ have been populated using the $^{92}\mathrm{Mo}(^{54}\mathrm{Fe},\mathit{pn})^{144}\mathrm{Ho}$ reaction and studied using the recoil-isomer-tagging technique. The alignment properties and signature splitting of the rotational band above the ${I}^{\ensuremath{\pi}}=({8}^{+})^{144m}\mathrm{Ho}$ isomer have been analyzed and the isomer confirmed to have a $\ensuremath{\pi}{h}_{11/2}\ensuremath{\bigotimes}\ensuremath{\nu}{h}_{11/2}$ two-quasiparticle configuration. The configuration-constrained blocking method has been used to calculate the shapes of the ground and isomeric states, which are both predicted to have triaxia…
Neutrino-deuteron scattering: Uncertainty quantification and new L1,A constraints
2020
We study neutral- and charged-current (anti)neutrino-induced dissociation of the deuteron at energies from threshold up to 150 MeV by employing potentials, as well as one- and two-body currents, derived in chiral effective field theory ($\ensuremath{\chi}\mathrm{EFT}$). We provide uncertainty estimates from $\ensuremath{\chi}\mathrm{EFT}$ truncations of the electroweak current, dependences on the $\ensuremath{\chi}\mathrm{EFT}$ cutoff, and variations in the pool of fit data used to fix the low-energy constants of $\ensuremath{\chi}\mathrm{EFT}$. At 100 MeV of incident (anti)neutrino energy, these uncertainties amount to about 2--3% and are smaller than the sensitivity of the cross sections …
Polarization observables for elastic electron scattering off a moving nucleon
2019
General expressions for all parity-conserving polarization observables of elastic electron-nucleon scattering in the one-photon exchange approximation are derived for a general frame of reference, i.e.\ not assumming scattering off a nucleon at rest and not specializing to a specific system of coordinates. Essentially, the given expressions are also valid for the inverse process, i.e.\ nucleon scattering off electrons.
σ→γγWidth from Nucleon Electromagnetic Polarizabilities
2008
The lightest QCD resonance, the $\ensuremath{\sigma}$, has been recently fixed in the $\ensuremath{\pi}\ensuremath{\pi}$ scattering amplitude. The nature of this state remains nowadays one of the most intriguing and difficult issues in particle physics. Its coupling to photons is crucial for discriminating its structure. We propose a new method that fixes this coupling using only available precise experimental data on the proton electromagnetic polarizabilities together with analyticity and unitarity. By taking into account the uncertainties in the analysis and in the parameter values, our result is ${\ensuremath{\Gamma}}_{\mathrm{pole}}(\ensuremath{\sigma}\ensuremath{\rightarrow}\ensuremat…