Values Of Four-momentum Transfer Research Articles

Transverse Spin Asymmetries in the CNI Region of Elastic Proton-Proton Scattering at s=200 GeV

Precise measurements of transverse spin asymmetries in proton-proton elastic scattering at very small values of four-momentum transfer squared, [Formula: see text], have been performed using the Relativistic Heavy Ion Collider (RHIC) polarized proton beams. The measurements of both single and double spin asymmetries were made at the center-of-mass energy [Formula: see text] GeV and in the region [Formula: see text] [Formula: see text], which was accessed using Roman Pot devices incorporated into the STAR experimental setup. The obtained set of asymmetries is sensitive to the poorly known hadronic contribution to the spin-flip amplitudes and provide significant constraints for the theoretical descriptions of the reaction mechanism of proton-proton elastic scattering at high energies.

Tensor polarization in elastic electron-deuteron scattering in the momentum transfer range 3.8

The tensor polarization of the recoil deuteron in elastic electron-deuteron scattering has been measured at the Bates Linear Accelerator Center at three values of four-momentum transfer [ital Q]=3.78, 4.22, and 4.62 fm[sup [minus]1], corresponding to incident electron energies of 653, 755, and 853 MeV. The scattered electrons and the recoil deuterons were detected in coincidence. The recoil deuterons were transported to a liquid hydrogen target to undergo a second scattering. The angular distribution of the [ital [rvec d]]-[ital p] scattering was measured using a polarimeter. The polarimeter was calibrated in an auxiliary experiment using a polarized deuteron beam at the Laboratoire National Saturne. A Monte Carlo procedure was used to generate interpolated calibration data because the energy spread in the deuteron energies in the Bates experiment spanned the range of deuteron energies in the calibration experiment. The extracted values of [ital t][sub 20] are compared to predictions of different theoretical models of the electromagnetic form factors of the deuteron: nonrelativistic and relativistic nucleon-meson dynamics, Skyrme model, quark models, and perturbative quantum chromodynamics. Along with the world data the structure functions [ital A]([ital Q]) and [ital B]([ital Q]) are used to separate the charge monopole and charge quadrupole form factors ofmore » the deuteron. A node in the charge monopole form factor is observed at [ital Q]=4.39[plus minus]0.16 fm[sup [minus]1].« less

Measurement of tensor polarization in elastic electron-deuteron scattering in the momentum-transfer range 3.8

The tensor polarization {ital t}{sub 20} of the recoil deuteron in elastic {ital e}-{ital d} scattering has been measured for three values of four-momentum transfer, {ital q}=3.78, 4.22, and 4.62 fm{sup {minus}1}. The data have been used to locate the first node in the charge monopole form factor of the deuteron at {ital q}=4.39{plus minus}0.16 fm{sup {minus}1}. The results for {ital t}{sub 20} are in reasonable agreement with expectations based on the nucleon-meson description of nuclear dynamics.

Polarized target asymmetry for pi-zero photoproduction at 4 GeV

The polarized target asymmetry parameter has been measured for single π o photoproduction from hydrogen at 4 GeV and values of four-momentum transfer squared between −0.15 (GeV/ c) 2 and −1.8 (GeV/ c) 2.

Search forT-Invariance Violation in the Inelastic Scattering of Electrons from a Polarized Proton Target

We have searched for an asymmetry in the inelastic scattering of electrons from a polarized proton target in the region of resonance excitation, at values of four-momentum transfer squared of 0.4, 0.6, and 1.0 ${(\mathrm{G}\mathrm{e}\mathrm{V}/\mathit{c})}^{2}$. Data were also taken using an incident positron beam in order to distinguish any possible effect of time-reversal invariance violation from that due to higher-order (${\ensuremath{\alpha}}^{3}$) contributions to the scattering. No sizable violation of time-reversal invariance was found.

Evaluations of mass of target isobar and four-momentum transfer in cosmic-ray jets

Direct quantitative evaluations of four-momentum transfer, inelasticity and mass of target isobars in cosmic-ray jets have been carried out with the information of target particles. Average value of fourmomentum transfer to target particles ΔN is found to be ∼ 0.7 GeV for the jets with /γc>=18.5. Occurence of jets with small four-momentum transfer (ΔN⩽1 GeV) is found to be ∼ 0.5 for the primary energy region of (1011÷1013) eV and ∼ 0.6 for that of (1013÷1014) eV. Slight tendency to correlation between ΔN andns is seen although ΔN is evaluated independently ofns. Target isobars so far investigated are dominated by the resonance of isotopic spinI=3/2. When one takes into account the formation of target isobars, the value of four-momentum transfer ΔN increases slightly.