419 research outputs found
Space-time properties of the higher twist amplitudes
A consistent and intuitive description of the twist-4 corrections to the
hadron structure functions is presented in a QCD-improved parton model using
time-ordered perturbative theory, where the collinear singularities are
naturally eliminated. We identify the special propagators with the backward
propagators of partons in time order.Comment: 18 Pages, Latex, 8 Ps figures, To appear in Phys. Rev.
Naringin supplementation affects performance, carcass traits, meat quality and oxidative stability of finishing pigs
Naringin is a major flavanone derivate that has many important biological functions in animals. However, its effect on pigs is unknown. The aim of this study was to investigate the effect of naringin supplementation on performance, carcass traits, meat quality and oxidative stability in finishing pigs. Ninety-six pigs, with an average initial body weight of 66.2 ± 0.63 kg, were randomly divided into four groups. One group was fed a basal diet without supplementation (control), and the three others were fed diets supplemented with 0.5, 1.0 or 1.5 g naringin /kg DM of feed for 50 days. Each treatment was replicated six times with four pigs per replicate. Feed and water were available ad libitum. The 0.5 g/kg naringin treatment group had an improved loin eye muscle area, reduced serum triglycerides and were leaner compared with the other groups. Pigs in the 1.5 g/kg naringin treatment had higher pH45min values and inosine monophosphate concentrations, and lower MyHC IIb mRNA expression in muscle than the other groups. MyHC IIa mRNA expression was significantly up-regulated in all naringin-supplemented diet groups. Naringin significantly increased superoxide dismutase (SOD) activity and total anti-oxidative capacity in meat, as well as SOD and glutathione peroxidase activity in the liver. These results indicate that the dietary addition of naringin at 0.5 g/kg improved carcass characteristics, while 1.5 g/kg improved the oxidative stability and pork quality in finishing pigs.
Keywords: antioxidant capacity; carcass characteristics; naringin-supplemented diets; pork qualit
Accessing Transversity in Double-Spin Asymmetries at the BNL-RHIC
We give upper bounds for transverse double-spin asymmetries in polarized
proton-proton collisions by saturating the positivity constraint for the
transversity densities at a low hadronic resolution scale. We consider prompt
photon, jet, pion, and heavy flavor production at the BNL Relativistic Heavy
Ion Collider (RHIC). Estimates of the expected statistical accuracy for such
measurements are presented, taking into account the acceptance of the RHIC
detectors.Comment: 15 pages, LaTeX, 2 figures as eps file
Spin-dependent structure functions and for inclusive spin-half baryon production in electron-positron annihilation
Two spin-dependent structure functions and for the
inclusive spin-half baryon production in electron-positron annihilation are
studied in the context of QCD factorization as well as in the naive quark
parton model. As a result, it is found that the sum of and is related to and , two quark fragmentation functions
defined by Jaffe and Ji. In connection with the measurement of quark
fragmentation functions, the possible phenomenological consequences are
discussed.Comment: RevTex, four Ps figures, to appear in Phys. Rev.
Novel Structure Function for Photon Fragmentation into a Hyperon and Transverse Polarization in Unpolarized Electron-Positron Annihilation
The possibility is examined for the inclusive in unpolarized
electron-positron annihilation to be transversely polarized. Due to final-state
interactions, there exists a novel structure function for the
inclusive hyperon (or any other baryons) production from the
unpolarized time-like photon fragmentation, which makes contribution to the
transverse polarization in the unpolarized electron-positron
annihilation.Comment: RevTex, 4 pages, the version appearing in Phys. Rev.
Jet broadening in deeply inelastic scattering
In deeply inelastic lepton-nucleus scattering (DIS), the average jet
transverse momentum is broadened because of the multiple scattering in the
nuclear medium. The size of jet broadening is proportional to the multi-parton
correlation functions inside nuclei. We show that at leading order, jet
broadening in DIS and nulcear enhancement in di-jet momentum imbalance and
Drell-Yan share the same four-parton correlation functions. We
argue that jet broadening in DIS provide an indenpendent measurement of the
four-parton correlation functions and a test of QCD treatment of multiple
scattering.Comment: Latex, 18 pages, five figures; a few typos were correcte
Reconstruction of a Nonminimal Coupling Theory with Scale-invariant Power Spectrum
A nonminimal coupling single scalar field theory, when transformed from
Jordan frame to Einstein frame, can act like a minimal coupling one. Making use
of this property, we investigate how a nonminimal coupling theory with
scale-invariant power spectrum could be reconstructed from its minimal coupling
counterpart, which can be applied in the early universe. Thanks to the coupling
to gravity, the equation of state of our universe for a scale-invariant power
spectrum can be relaxed, and the relation between the parameters in the action
can be obtained. This approach also provides a means to address the Big-Bang
puzzles and anisotropy problem in the nonminimal coupling model within Jordan
frame. Due to the equivalence between the two frames, one may be able to find
models that are free of the horizon, flatness, singularity as well as
anisotropy problems.Comment: 31 pages, 4 figure
Nonperturbative Description of Deep Inelastic Structure Functions in Light-Front QCD
We explore the deep inelastic structure functions of hadrons
nonperturbatively in an inverse power expansion of the light-front energy of
the probe in the framework of light-front QCD. We arrive at the general
expressions for various structure functions as the Fourier transform of matrix
elements of different components of bilocal vector and axial vector currents on
the light-front in a straightforward manner. The complexities of the structure
functions are mainly carried by the multi-parton wave functions of the hadrons,
while, the bilocal currents have a dynamically dependent yet simple structure
on the light-front in this description. We also present a novel analysis of the
power corrections based on light-front power counting which resolves some
ambiguities of the conventional twist analysis in deep inelastic processes.
Further, the factorization theorem and the scale evolution of the structure
functions are presented in this formalism by using old-fashioned light-front
time-ordered perturbation theory with multi-parton wave functions.
Nonperturbative QCD dynamics underlying the structure functions can be explored
in the same framework. Once the nonperturbative multi-parton wave functions are
known from low-energy light-front QCD, a complete description of deep inelastic
structure functions can be realized.Comment: Revtex, 30 pages and no figur
Q^2-Evolution of Nucleon's Chiral-Odd Twist-3 Structure Function: h_L(x,Q^2)
We investigate the -evolution of the chiral-odd spin-dependent parton
distribution relevant for the polarized Drell-Yan processes.
The results are obtained in the leading logarithmic order in the framework of
the renormalization group and the standard QCD perturbation theory. We
calculate the anomalous dimension matrix for the twist-3 operators for
in the one-loop order. The operator mixing among the relevant twist-3 operators
including the operators proportional to the QCD equations of motion is treated
properly in a consistent scheme. Implications for future experiments are also
discussed.Comment: HUPD-9419, Latex file, 21 pages, 7 figures available on reques
Wilson Lines off the Light-cone in TMD PDFs
Transverse Momentum Dependent (TMD) parton distribution functions (PDFs) also
take into account the transverse momentum () of the partons. The
-integrated analogues can be linked directly to quark and gluon matrix
elements using the operator product expansion in QCD, involving operators of
definite twist. TMDs also involve operators of higher twist, which are not
suppressed by powers of the hard scale, however. Taking into account gauge
links that no longer are along the light-cone, one finds that new distribution
functions arise. They appear at leading order in the description of azimuthal
asymmetries in high-energy scattering processes. In analogy to the collinear
operator expansion, we define a universal set of TMDs of definite rank and
point out the importance for phenomenology.Comment: 12 pages, presented by the first author at the Light-Cone Conference
2013, May 20-24, 2013, Skiathos, Greece. To be published in Few Body System
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