نتایج جستجو برای: spin asymmetry
تعداد نتایج: 156923 فیلتر نتایج به سال:
We present measurements of D--> KS0 pi and D--> KL0 pi branching fractions using 281 pb(-1) of psi(3770) data at the CLEO-c experiment. We find that B(D0--> KS0 pi 0) is larger than B(D0--> KL0 pi 0), with an asymmetry of R(D0)=0.108+/-0.025+/-0.024. For B(D+--> KS0 pi+) and B(D+--> KL0 pi+), we observe no measurable difference; the asymmetry is R(D+)=0.022+/-0.016+/-0.018. The D0 asymmetry is ...
We calculate a single transverse-spin asymmetry for the Drell-Yan lepton-pair’s angular distribution in perturbative QCD. At leading order in the strong coupling constant, the asymmetry is expressed in terms of a twist-3 quark-gluon correlation function T (V ) F (x1, x2). In our calculation, the same result was obtained in both light-cone and covariant gauge in QCD, while keeping explicit elect...
We report the results of resonant magnetic XUV reflectivity experiments performed at the XUV free-electron laser FERMI. Circularly polarized XUV light with the photon energy tuned to the Fe M2,3 edge is used to measure resonant magnetic reflectivities and the corresponding Q-resolved asymmetry of a Permalloy/Ta/Permalloy trilayer film. The asymmetry exhibits ultrafast changes on 240 fs time sca...
We consider the leading twist T -odd contributions as the dominant source of the cos 2φ azimuthal asymmetry in unpolarized pp̄ → μμ X dilepton production in Drell-Yan Scattering. This asymmetry contains information on the distribution of quark transverse spin in an unpolarized proton. In a parton-spectator framework we estimate these asymmetries at 50 GeV center of mass energy. This azimuthal as...
We study a weighted asymmetry in the azimuthal distribution of photon-jet pairs produced in the process pp-->gamma jet X with a transversely polarized proton. We focus on the contribution of the Sivers effect only, considering experimental configurations accessible at the Relativistic Heavy Ion Collider. We show that predictions for the asymmetry, obtained in terms of gluonic-pole cross section...
We present measurements of D → K Sπ and D → K 0 Lπ branching fractions using 281 pb −1 of ψ(3770) data at the CLEO-c experiment. We find that B(D → K Sπ ) is larger than B(D → K Lπ ), with an asymmetry of R(D) = 0.108 ± 0.025 ± 0.024. For B(D → K Sπ ) and B(D → K Lπ ), we observe no measurable difference; the asymmetry is R(D) = 0.022±0.016±0.018. The D asymmetry is consistent with the value ba...
We study the single transverse-spin asymmetry for open charm production in the semiinclusive lepton-hadron deep inelastic scattering (SIDIS) and pp collision. Within collinear factorization approach, we find that the asymmetry is sensitive to the twist-3 trigluon correlation functions in the proton. With a simple model for the trigluon correlation functions, we estimate the asymmetry in SIDIS f...
The measurement of the polarized gluon distribution function ∆g(x) from photon gluon fusion processes in electron proton deep inelastic scattering producing two jets has been investigated. The study is based on the MEPJET simulation program. The size of the expected spin asymmetry and corresponding statistical uncertainties for a possible measurement with polarized beams of electrons and proton...
Using Sphinx tt, a new MC simulation program for transverse polarized nucleon–nucleon scattering based on Pythia 5.6, we calculate the transverse double spin asymmetry ATT in the Drell-Yan process. If one assumes (quite arbitrarily) that the transversity parton distribution δq(x,Q2) equals the helicity distribution ∆q(x,Q2) at some low Q0 scale, the resulting asymmetry is of order 1%. In this c...
We report measured dipolar asymmetry ratios at the LIII edges of the heavy rare-earth metals. The results are compared with a first-principles calculation and excellent agreement is found. A simple model of the scattering is developed, enabling us to reinterpret the resonant x-ray scattering in these materials and to identify the peaks in the asymmetry ratios with features in the spin and orbit...
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