124133456
About the Clusterization of Partons in the Hadron Processes
In this paper the concept of the clusterizations of partons of two kinds is proposed. In terms of the model of quark recombination and the perturbative QCD a set of distribution functions describing the clusterization of the second kind are separated from the quark fragmentation function, and so some quantitative phenomenological information about the QCD soft processes is obtained.
18244927
Nuclear Shadowing and Antishadowing in a Unitarized BFKL Equation
The nuclear shadowing and antishadowing effects are explained by a unitarized BFKL equation. The Q2and x-variations of the nuclear parton distributions are detailed based on the level of the unintegrated gluon distribution. In particular, the asymptotical behavior of the unintegrated gluon distribution near the saturation limit in nuclear targets is studied. Our results in the nuclear targets are insensitive to the input distributions if the parameters are fixed by the data of a free proton. PACS numbers: 13.60.Hb; 12.38.Bx. keywords: nuclear shadowing and antishadowing; unintegrated gluon distribution in nuclei; QCD evolution equation Supported by National Natural Science Foundation of China 10135060, 10475028 and 10205004. Corresponding author, E-mail: weizhu @mail.ecnu.edu.cn
124473583
Partonic Structure of the Pomeron in the Modified GLR Equation
The gluon recombination effect in the pomeron is studied by using the modified Gribov–Levin–Ryskin evolution equation. We find that the measured parton distributions in the pomeron can be generated dynamically from a purely gluonic input on assuming a small size for the pomeron.
119716730
A twist-4 effect in the parton evolution processes
Recently, a research group reported that they can fit the F2 data well by using the Altarelli-Parisi evolution equation with a valence-like initial gluon distribution, which means that we need not consider the high twist effects in the proton. In this letter, we point out that their valence-like initial gluon distribution is unreasonable for the proton structure function. With the reasonable initial distributions, we find that the high twist corrections to the Altarelli-Parisi evolution equation is necessary.
122365434
Bag skin effect for Friedberg-Lee model
Importance of the bag skin effect to determine the parameters of the Friedberg-Lee model is pointed out. The European Muon Collaboration (EMC) effect regarded as a bag skin effect can be used to determine the parameters of this model.
124556870
A New Effect in the QCD Fusion of Nuclear Partons
The parton fusion in nucleus at the leading order of recombination is investigated based on perturbative QCD. We compute various cut diagrams including the nuclear parton fusion, and find that the parton-fusion effects depend on the nuclear QCD structure.
120889394
Quark distributions in nuclei and nuclear effects on nucleon structure functions
Extended quark distribution functions are presented obtained by fitting a large amount of experimental data of the l-A DIS process on the basis of an improved nuclear density model. The experimental data of l-A DIS processes with A ≥ 3 in the region 0.0010 ≤ x ≥ 0.9500 are quite satisfactorily described by using the extended formulae. Our knowledge of the influence of nuclear matter on the quark distributions is deepened.
123012350
Phenomenological study of Sudakov effects in the pion form factor
The pion electromagnetic form factor with leading and next-to-leading twist corrections is studied in the framework of the pQCD approach. We find that the Sudakov effects provide a weak suppression of the nonperturbative contributions at the experimental accessible energy region. We also find a large twist-3 contribution. Our conclusion is that the prediction of the pion form factor in the pQCD approach is not precise.
14637708
Factorization and polarization in two charmed-meson B decays
We provide a comprehensive test of factorization in the heavy–heavy B decays motivated by the recent experimental data from the BELLE and BABAR collaborations. The penguin effects are not negligible in the B decays with two pseudoscalar mesons. The direct CP asymmetries are found to be a few percent. We give estimates on the weak annihilation contributions by analogy to the observed annihilation-dominated processes. The Nc insensitivity of branching ratios indicates that the soft final state interactions are not dominant. We also study the polarizations in B→D*D(s)* decays. The power law shows that the transverse perpendicular polarization fraction is small. The effects of the heavy quark symmetry breaking caused by the perturbative QCD and power corrections on the transverse polarization are also investigated.
119499375
Productions of K*0(1430) and K(1) in B decays
We study the productions of p-wave mesons $K^*_{0}(1430)$, $K_{1}(1270)$ and $K_{1}(1400)$ in B decays. By the generalized factorization approach, we find that the branching ratios of $B\to K^*_{0}(1430) \phi$ are similar to those of $B\to K \phi$ while the branching ratios of $B\to K_{1}(1270) \phi$ and $B\to K_{1}(1400) \phi$ are $O(10^{-5})$ and $O(10^{-6})$, respectively. In terms of the observation of $B\to K_{1}(1270) \gamma$ by BELLE, we can remove the sign ambiguity in the mixing angle for physical states $K_1(1270)$ and $K_{1}(1400)$. In addition, we analyze annihilation contributions in the decays $B\to K_1 \phi$ and we conclude that they could be neglected.
119388505
Sudakov effects in BBNS approach
The end-point singularity is an unsolved problem in BBNS approach, Incorporating the partonic transverse momentum and the Sudakov form factor, this problem can be solved model-independently. We discuss the Sudakov effects in BBNS approach. The BBNS approach is compared with the modified PQCD approach. The main idea of Sudakov form factor is briefly discussed. Our conclusion is that the twist-3 contribution for the hard spectator scattering is numerically not important in B --> pi pi decays, compared with the twist-2 contribution. (C) 2001 Published by Elsevier Science B.V.