4,313 research outputs found

    Single Transverse-Spin Asymmetry in Large PTP_T Open Charm Production at an Electron-Ion Collider

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    We discuss the single transverse-spin asymmetry (SSA) to be observed in the DD-meson production with large transverse-momentum in semi-inclusive deep inelastic scattering, ep↑→eDXe p^\uparrow \rightarrow e D X. This contribution is embodied as a twist-3 mechanism in the collinear factorization, which is induced by purely gluonic correlation inside the transversely-polarized nucleon, in particular, by the three-gluon correlation effects. The complete formula for the corresponding SSA in the leading-order QCD is expressed in terms of the four independent gluonic correlation functions and reveals the five independent structures with respect to the dependence on the azimuthal angle for the produced DD-meson. We present the numerical calculations of the SSA formula at the kinematics relevant to a future Electron Ion Collider.Comment: 16 pages, 7 figure

    On the contribution of twist-3 multi-gluon correlation functions to single transverse-spin asymmetry in SIDIS

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    We study the single spin asymmetry (SSA) induced by purely gluonic correlation inside a nucleon, in particular, by the three-gluon correlation functions in the transversely polarized nucleon, p↑p^\uparrow. This contribution is embodied as a twist-3 mechanism in the collinear factorization framework and controls the SSA to be observed in the DD-meson production with large transverse-momentum in semi-inclusive DIS (SIDIS), ep↑→eDXep^\uparrow \rightarrow eDX. We define the relevant three-gluon correlation functions in the nucleon, and determine their complete set at the twsit-3 level taking into account symmetry constraints in QCD. We derive the single-spin-dependent cross section for the DD-meson production in SIDIS, taking into account all the relevant contributions at the twist-3 level. The result is obtained in a manifestly gauge-invariant form as the factorization formula in terms of the three-gluon correlation functions and reveals the five independent structures with respect to the dependence on the azimuthal angle for the produced DD meson. We also demonstrate the remarkable relation between the twist-3 single-spin-dependent cross section and twist-2 cross sections for the DD-meson production, as a manifestation of universal structure behind the SSA in a variety of hard processes.Comment: 8 pages, 2 figures. To appear in the proceedings of the 19th International Spin Physics Symposium (SPIN2010), Juelich, Germany, Sept.27 - Oct.2, 201

    Muon-spin-relaxation and magnetic-susceptibility studies of effects of the magnetic impurity Ni on the Cu-spin dynamics and superconductivity in La_2-x_Sr_x_Cu_1-y_Ni_y_O_4_ with x = 0.13

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    Effects of the magnetic impurity Ni on the Cu-spin dynamics and superconductivity have been studied in La_2-x_Sr_x_Cu_1-y_Ni_y_O_4_ with x = 0.13 changing y finely up to 0.10. Compared with the case of the nonmagnetic impurity Zn, it has been found from the muon-spin-relaxation measurements that a large amount of Ni is required to stabilize a magnetic order of Cu spins. However, the evolution toward the stabilization of the magnetic order with increasing impurity concentration is qualitatively similar to each other. The area of the non-superconducting and slowly fluctuating or static region of Cu spins around Ni has been found to be smaller than that around Zn, suggesting that the pinning of rather long-ranged dynamical spin correlation such as the so-called dynamical stripe by Ni is weaker than that by Zn. This may be the reason why Zn destroys the superconductivity in the hole-doped high-T_c_ cuprates more markedly than Ni.Comment: 4 pages, 4 figures, accepted for publication in Phys. Rev.

    Probing the twist-3 multi-gluon correlation functions by pp \to DX

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    We study the single spin asymmetry (SSA) for the D-meson production ANDA_N^D in the pppp collision, p↑pβ†’DXp^\uparrow p\to DX, in the framework of the collinear factorization. Since the charm quark is mainly produced through the ccΛ‰c\bar{c}-pair creation from the gluon-fusion process, this is an ideal process to probe the twist-3 triple-gluon correlation functions in the polarized nucleon. We derive the corresponding cross section formula for the contribution of the triple-gluon correlation function to ANDA_N^D in p↑pβ†’DXp^\uparrow p\to DX, applying the method developed for ep↑→eDXep^\uparrow\to eDX in our previous study. As in the case of ep↑→eDXep^\uparrow\to eDX, our result differs from a previous study in the literature. We will also present a simple estimate of the triple-gluon correlation functions based on the preliminary data on ANDA_N^D by RHIC.Comment: to appear in the proceedings of the 19th International Spin Physics Symposium (Spin2010), Sept.27 - Oct.2, 2010, Juelich, Germany, 5 pages, 2 figure

    Three-gluon contribution to the single spin asymmetry in Drell-Yan and direct-photon processes

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    We derive the single-spin-dependent cross section for the Drell-Yan lepton-pair production and the direct-photon production in the pppp-collision induced by the twist-3 three-gluon correlation functions in the transversely polarized nucleon in the leading order with respect to the QCD coupling constant. Combined with the contribution from the twist-3 quark-gluon correlation functions in the literature, this completes the twist-3 cross section for these processes. We also present a model calculation of the asymmetry for the direct photon production at the RHIC energy, demonstrating the sensitivity of the asymmetry to the form of the three-gluon correlation functions. In particular, we show that the asymmetry in the backward direction of the polarized nucleon is determined by the small-xx behavior of the correlation functions.Comment: 15 pages, 3 figure

    A new screening function for Coulomb renormalization

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    We introduce a new screening function which is useful for the few-body Coulomb scattering problem in ``screening and renormalization'' scheme. The new renormalization phase factor of the screening function is analytically shown. The Yukawa type of the screening potential has been used in several decades, we modify it to make more useful. As a concrete example, we compare the proton-proton scattering phase shifts calculated from these potentials. The numerical results document that high precision calculations of the renormalization are performed by the new screening function.Comment: 4 pages, 8 figure
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