1,721,006 research outputs found
Recommended from our members
High-Resolution Spectroscopy of N-16(Lambda) by Electroproduction
No full textRecommended from our members
Compton-scattering cross section on the proton at high momentum transfer
No full textPrecision Measurements of A^n1 in the Deep Inelastic Regime
No full textWe have performed precision measurements of the double-spin virtual-photon asymmetry A1 on the neutron in the deep inelastic scattering regime, using an open-geometry, large-acceptance spectrometer and a longitudinally and transversely polarized 3He target. Our data cover a wide kinematic range 0.277 ≤ x ≤ 0.548 at an average Q 2 value of 3.078 (GeV/c)2, doubling the available high-precision neutron data in this x range. We have combined our results with world data on proton targets to make a leading-order extraction of the ratio of polarized-to-unpolarized parton distribution functions for up quarks and for down quarks in the same kinematic range. Our data are consistent with a previous observation of an An 1 zero crossing near x = 0.5. We find no evidence of a transition to a positive slope in (d + ¯ d)/(d + ¯ d) up to x = 0.548Physic
Recommended from our members
High resolution spectroscopy of B-12(Lambda) by electroproduction
No full textRosenbluth Separation of the pi(0) Electroproduction Cross Section
No full textWe present deeply virtual pi(0) electroproduction cross-section measurements at x(B) = 0.36 and three different Q(2) values ranging from 1.5 to 2 GeV2, obtained from Jefferson Lab Hall A experiment E07-007. The Rosenbluth technique is used to separate the longitudinal and transverse responses. Results demonstrate that the cross section is dominated by its transverse component and, thus, is far from the asymptotic limit predicted by perturbative quantum chromodynamics. Nonetheless, an indication of a nonzero longitudinal contribution is provided by the measured interference term sigma(LT). Results are compared with several models based on the leading-twist approach of generalized parton distributions (GPDs). In particular, a fair agreement is obtained with models in which the scattering amplitude includes convolution terms of chiral-odd (transversity) GPDs of the nucleon with the twist-3 pion distribution amplitude. This experiment, together with previous extensive unseparated measurements, provides strong support to the exciting idea that transversity GPDs can be accessed via neutral pion electroproduction in the high-Q(2) regime.Physic
Exclusive Neutral Pion Electroproduction in the Deeply Virtual Regime
Get PDFWe present measurements of the ep→epπ0 cross section extracted at two values of four-momentum transfer Q2=1.9 GeV2 and Q2=2.3 GeV2 at Jefferson Lab Hall A. The kinematic range allows one to study the evolution of the extracted cross section as a function of Q2 and W. Results are confronted with Regge-inspired calculations and GPD predictions. An intepretation of our data within the framework of semi-inclusive deep inelastic scattering is also discussed
Mjerenje odbojne polarizacije u reakciji 16^O (→ e , e′ → p)
Get PDFThe longitudinal and transverse components of the polarization of the outgoing proton were measured for the reaction 16^O (→ e , e′ → p) at a four-momentum transfer squared of 0.8 GeV2 in quasifree kinematics. These were the first measurements of polarization transfer observables for a complex nucleus. Comparison of the ratio of the transverse and longitudinal polarization to theoretical predictions allows the study of modification of the proton’s form factors in the nuclear medium.Mjerile su se uzdužna i poprečna komponenta polarizacije izlaznih protona u reakciji 16^O (→ e , e′ → p) za kvadrat prijenosa impulsa od 0.8 GeV2 , u kvazislobodnim kinematičkim uvjetima. Ovo su prva mjerenja prijenosa polarizacije za složenu jezgru. Usporedba omjera poprečne i uzdužne polarizacije s teorijskim predviđanjima omogućava proučavanje promjena faktora oblika protona kada je u nuklearnom okruženju
Scaling Tests of the Cross Section for Deeply Virtual Compton Scattering
Get PDFWe present the first measurements of the e⃗p→epγ cross section in the deeply virtual Compton scattering (DVCS) regime and the valence quark region. The Q2 dependence (from 1.5 to 2.3 GeV2) of the helicity-dependent cross section indicates the twist-2 dominance of DVCS, proving that generalized parton distributions (GPDs) are accessible to experiment at moderate Q2. The helicity-independent cross section is also measured at Q2=2.3 GeV2. We present the first model-independent measurement of linear combinations of GPDs and GPD integrals up to the twist-3 approximation
Single Spin Asymmetries in Charged Pion Production from Semi-Inclusive Deep Inelastic Scattering on a Transversely Polarized (3)He Target at Q(2)=1.4–2.7 GeV(2)
Get PDFWe report the first measurement of target single spin asymmetries in the semi-inclusive 3He(e,e′π±)X reaction on a transversely polarized target. The experiment, conducted at Jefferson Lab using a 5.9 GeV electron beam, covers a range of 0.1622. The Collins and Sivers moments were extracted from the azimuthal angular dependence of the measured asymmetries. The π± Collins moments for 3He are consistent with zero, except for the π+ moment at x=0.35, which deviates from zero by 2.3σ. While the π- Sivers moments are consistent with zero, the π+ Sivers moments favor negative values. The neutron results were extracted using the nucleon effective polarization and measured cross section ratios of proton to 3He, and are largely consistent with the predictions of phenomenological fits and quark model calculations
Recommended from our members
The reaction dynamics of the {sup 16}O(e,e{prime}p) cross section at high missing energies
No full textThe authors measured the cross section and response functions (R-L, R-T, and R-LT) for the {sup 16}O(e,e{prime}p) reaction in quasielastic kinematics for missing energies 25 <= E-miss <= 120 MeV at various missing momenta P-miss <= 340 MeV/c. For 25 < E-miss < 50 MeV and P-miss approx 60 MeV/c, the reaction is dominated by single-nucleon knockout from the 1s1/2-state. At larger P-miss, the single-particle aspects are increasingly masked by more complicated processes. For E-miss > 60 MeV and P-miss > 200 MeV/c, the cross section is relatively constant. Calculations which include contributions from pion exchange currents, isobar currents and short-range correlations account for the shape and the transversity but only for half of the magnitude of the measured cross section
- …
