10 research outputs found
Subleading-twist effects in single-spin asymmetries in semi-inclusive deep-inelastic scattering on a longitudinally polarized hydrogen target
Single-spin asymmetries in the semi-inclusive production of charged pions in
deep-inelastic scattering from transversely and longitudinally polarized proton
targets are combined to evaluate the subleading-twist contribution to the
longitudinal case. This contribution is significantly positive for (\pi^+)
mesons and dominates the asymmetries on a longitudinally polarized target
previously measured by \hermes. The subleading-twist contribution for (\pi^-)
mesons is found to be small
Quark fragmentation to , , , and in the nuclear environment
The influence of the nuclear medium on lepto-production of hadrons was
studied in the HERMES experiment at DESY in semi-inclusive deep-inelastic
scattering of 27.6 GeV positrons off deuterium, nitrogen and krypton targets.
The differential multiplicity for krypton relative to that of deuterium has
been measured for the first time for various identified hadrons (,
, , , , and ) as a function of the virtual
photon energy , the fraction of this energy transferred to the hadron,
and the hadron transverse momentum squared . The multiplicity ratio is
strongly reduced in the nuclear medium at low and high , with
significant differences among the various hadrons. The distribution of the
hadron transverse momentum is broadened towards high in the nuclear
medium, in a manner resembling the Cronin effect previously observed in
collisions of heavy ions and protons with nuclei.Comment: 8 pages, 5 figure
Kybernetics of cardio-respiratory synchrony: Characterization by modulating cardiac frequency
Nutrition: a hard nut to crack. An exploration of the knowledge, attitudes and activities of qualified nurses in relation to nutritional nursing care
Menu changes and their effects on the nutritional content of menus and nutritional status of elderly, hospitalized, mental health patients
The Characterization of Feces and Urine: A Review of the Literature to Inform Advanced Treatment Technology
Hard exclusive electroproduction of π<sup>+</sup>π<sup>-</sup>pairs
Hard exclusive electroproduction of pi(+) pi(-) pairs off hydrogen and deuterium targets has been studied by the HERMES experiment at DESY Legendre moments (P-1) and (P-3) of the angular distributions of pi(+) mesons in the center-of-mass frame of the pair have been measured for the first time. Their dependence on the pi(+) pi(-) invariant mass can be understood as being due to the interference between relative P-wave (isovector) and S-, D-wave (isoscalar) states of the two pions. The increase in magnitude of (P-1) as Bjorken x increases is interpreted in the framework of generalized parton distributions as an enhancement of flavour non-singlet qq exchange for larger values of x, which leads to a sizable admixture of isoscalar and isovector pion pairs. In addition, the interference between P-wave and D-wave states separately for transverse and longitudinal pion pairs has been studied. The data indicate that in the f(2)(1270) region at [Q(2)] = 3 GeV2 higher-twist effects can be as large as the leading-twist longitudinal component