نتایج جستجو برای: spin asymmetry
تعداد نتایج: 156923 فیلتر نتایج به سال:
We report the first measurement of the transverse momentum dependence of double-spin asymmetries in semi-inclusive production of pions in deep-inelastic scattering off the longitudinally polarized proton. Data have been obtained using a polarized electron beam of 5.7 GeV with the CLAS detector at the Jefferson Lab (JLab). Modulations of single spin asymmetries over the azimuthal angle between l...
For any inclusive reaction of the type A1(spin 1/2)+A2(spin 1/2)-->B+X, we derive new positivity constraints on spin observables and study their implications for theoretical models in view, in particular, of accounting for future data from the polarized pp collider at Brookhaven RHIC. We find that the single transverse spin asymmetry A(N), in the central region for several processes, for exampl...
We investigate the alignment of ethylene and of some of its analogues via short, non-resonant laser pulses and show that it depends crucially on the nuclear spin of the molecules. We calculate the time-dependent alignment factors of the four nuclear spin isomers of ethylene and analyze them by comparison with the symmetric top molecule allene. Moreover, we explore how the nuclear spin selective...
We present a theoretical study of the spin-dependent electron scattering from screened impurities in III–V semiconductor quantum wells. The effective one band Hamiltonian and the Rashba spin-orbit interaction are used. We calculated the Mott scattering cross-section and the Sherman function for two-dimensional electrons spin-polarized parallel to the z-axis (direction of structure growth). We h...
We consider within a generalized QCD factorization approach, the high energy inclusive polarized process pp → π + X, including all intrinsic partonic motions. Several new spin and k⊥-dependent soft functions appear and contribute to cross sections and spin asymmetries. We present here formal expressions for transverse single spin asymmetries and double longitudinal ones. The transverse single s...
We elucidate the origin and nature of the D’yakonov-Perel’ spin relaxation in a quantum wire structure, showing (analytically) that there are three necessary conditions for it to exist: (i) transport must be multi-channeled, (ii) there must be a Rashba spin orbit interaction in the wire, and (iii) there must also be a Dresselhaus spin orbit interaction. Therefore, the only effective way to comp...
We investigate the origin of the cos 2φ azimuthal asymmetry in unpolarized semiinclusive DIS. The contributions to this asymmetry arising from the intrinsic transverse motion of quarks are explicitly evaluated, and predictions for the HERMES and COMPASS kinematic regimes are presented. We show that the effect of the leading-twist Boer-Mulders function h1 (x,k 2 T ), which describes a correlatio...
Preliminary results on azimuthal asymmetries in leptoproduction of real photons on an unpolarized hydrogen target measured at the HERMES experiment are presented [1]. The analysis of data taken with different beam charges and helicities allows for a simultaneous extraction of asymmetries originating from the interference term and the squared DVCS amplitude. Sizeable asymmetry amplitudes for the...
We calculate the strange quark and antiquark distributions of the nucleon by using the effective chiral quark model, and find that the strange-antistrange asymmetry can bring a contribution of about 60–100% to the NuTeV deviation of sin θw from the standard value measured in other electroweak processes. The results are insensitive to different inputs. The light-flavor quark asymmetry of d−u is ...
Experiment E158 at SLAC can measure an azimuthal asymmetry in single-spin, transversely polarized Møller scattering, e−↑e− → e−e−, which arises from a QED rescattering phase. We recompute the leading-order (one-loop) asymmetry, confirming previous results, and calculate the leading logarithmic QED corrections due to initial-state radiation from the beam and target electrons, and due to final-st...
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