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Register a new userFinal state interactions and the extraction of neutron single spin asymmetries from SIDIS by a transversely polarized $^3$He target
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The semi-inclusive deep inelastic electron scattering off transversely polarized $^3$He, i.e. the process, $e + vec{^3 {rm He}} to e + h+X$, with $h$ a detected fast hadron, is studied beyond the plane wave impulse approximation. To this end, a distorted spin-dependent spectral function of a nucleon inside an A=3 nucleus is actually evaluated through a generalized eikonal approximation, in order to take into account the final state interactions between the hadronizing system and the (A-1) nucleon spectator one. Our realistic description of both nuclear target and final state is a substantial step forward for achieving a reliable extraction of the Sivers and Collins single spin asymmetries of the free neutron. To illustrate how and to what extent the model dependence due to the treatment of the nuclear effects is under control, we apply our approach to the extraction procedure of the neutron single spin asymmetries from those measured for $^3$He for values of the kinematical variables relevant both for forthcoming experiments at Jefferson Lab and, with an exploratory purpose, for the future Electron Ion Collider.
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We report the first measurement of target single-spin asymmetries (A$_N$) in the inclusive hadron production reaction, $e~$+$~^3text{He}^{uparrow}rightarrow h+X$, using a transversely polarized $^3$He target. The experiment was conducted at Jefferson Lab in Hall A using a 5.9-GeV electron beam. Three types of hadrons ($pi^{pm}$, $text{K}^{pm}$ and proton) were detected in the transverse hadron momentum range 0.54 $<p_T<$ 0.74 GeV/c. The range of $x_F$ for pions was -0.29 $<x_F<$ -0.23 and for kaons -0.25 $<x_F<$-0.18. The observed asymmetry strongly depends on the type of hadron. A positive asymmetry is observed for $pi^+$ and $text{K}^+$. A negative asymmetry is observed for $pi^{-}$. The magnitudes of the asymmetries follow $|A^{pi^-}| < |A^{pi^+}| < |A^{K^+}|$. The K$^{-}$ and proton asymmetries are consistent with zero within the experimental uncertainties. The $pi^{+}$ and $pi^{-}$ asymmetries measured for the $^3$He target and extracted for neutrons are opposite in sign with a small increase observed as a function of $p_T$.
We report the measurement of beam-target double-spin asymmetries ($A_text{LT}$) in the inclusive production of identified hadrons, $vec{e}~$+$~^3text{He}^{uparrow}rightarrow h+X$, using a longitudinally polarized 5.9 GeV electron beam and a transversely polarized $^3rm{He}$ target. Hadrons ($pi^{pm}$, $K^{pm}$ and proton) were detected at 16$^{circ}$ with an average momentum $<$$P_h$$>$=2.35 GeV/c and a transverse momentum ($p_{T}$) coverage from 0.60 to 0.68 GeV/c. Asymmetries from the $^3text{He}$ target were observed to be non-zero for $pi^{pm}$ production when the target was polarized transversely in the horizontal plane. The $pi^{+}$ and $pi^{-}$ asymmetries have opposite signs, analogous to the behavior of $A_text{LT}$ in semi-inclusive deep-inelastic scattering.
We report the first measurement of target single spin asymmetries in the semi-inclusive $^3{He}(e,epi^pm)X$ reaction on a transversely polarized target. The experiment, conducted at Jefferson Lab using a 5.9 GeV electron beam, covers a range of 0.14 $< x <$ 0.34 with 1.3 $<Q^2<$ 2.7 GeV$^2$. The Collins and Sivers moments were extracted from the azimuthal angular dependence of the measured asymmetries. The extracted $pi^pm$ Collins moments for $^3$He are consistent with zero, except for the $pi^+$ moment at $x=0.34$, which deviates from zero by 2.3$sigma$. While the $pi^-$ Sivers moments are consistent with zero, the $pi^+$ Sivers moments favor negative values. The neutron results were extracted using the nucleon effective polarization and the measured cross section ratio of proton to $^3$He, and are largely consistent with the predictions of phenomenological fits and quark model calculations.
We report the first measurement of target single spin asymmetries of charged kaons produced in semi-inclusive deep inelastic scattering of electrons off a transversely polarized $^3{rm{He}}$ target. Both the Collins and Sivers moments, which are related to the nucleon transversity and Sivers distributions, respectively, are extracted over the kinematic range of 0.1$<$$x_{bj}$$<$0.4 for $K^{+}$ and $K^{-}$ production. While the Collins and Sivers moments for $K^{+}$ are consistent with zero within the experimental uncertainties, both moments for $K^{-}$ favor negative values. The Sivers moments are compared to the theoretical prediction from a phenomenological fit to the world data. While the $K^{+}$ Sivers moments are consistent with the prediction, the $K^{-}$ results differ from the prediction at the 2-sigma level.
It is argued that final state enhancements in production reactions at large momentum transfers, such as pp -> K^+ Lambda p, are primarily sensitive to the position of a virtual bound state pole in the Lambda p system rather than the Lambda p scattering length and effective range. These arguments are supported by a study of the dispersion relation derived to describe such processes as a function of the cut-off energy. This shows that the position of the virtual bound state is independent of the cut-off energy.
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