1,139 research outputs found
Parton Energy Loss and the Generalized Jet Transport Coefficient
We revisit radiative parton energy loss in deeply inelastic scattering (DIS)
off a large nucleus within the perturbative QCD approach. We calculate the
gluon radiation spectra induced by double parton scattering in DIS without
collinear expansion in the transverse momentum of initial gluons as in the
original high-twist approach. The final radiative gluon spectrum can be
expressed in terms of the convolution of hard partonic parts and unintegrated
or transverse momentum dependent (TMD) quark-gluon correlations. The TMD
quark-gluon correlation can be factorized approximately as a product of initial
quark distribution and TMD gluon distribution which can be used to define the
generalized or TMD jet transport coefficient. Under the static scattering
center and soft radiative gluon approximation, we recover the result by
Gylassy-Levai-Vitev (GLV) in the first order of the opacity expansion. The
difference as a result of the soft radiative gluon approximation is
investigated numerically under the static scattering center approximation.Comment: 33 pages in RevTeX with 30 figures, final version appeared in PRD
with additional typos correcte
Reexamining the doped two-legged Hubbard ladders
We revisit the ground state of the Hubbard model on 2-legged ladders in this
work. We perform DMRG calculation on large system sizes with large kept states
and perform extrapolation of DMRG results with truncation errors in the
converged region. We find the superconducting correlation exponent
extracted from the pair-pair correlation is very sensitive to the position of
the reference bond, reflecting a huge boundary effect on it. By systematically
removing the effects from boundary conditions, finite sizes, and truncation
errors in DMRG, we obtain the most accurate value of and so
far with DMRG. With these exponents, we confirm that the 2-legged Hubbard model
is in the Luther-Emery liquid phase with from tiny
doping near half-filling to hole doping. When the doping is increased to
, the behaviors of charge, pairing, and spin
correlations don't change qualitatively, but the relationship is likely to be violated. With the further increase of the doping
to , the quasi long-ranged charge correlation turns to a true
long-ranged charge order and the spin gap is closed, while the pair-pair
correlation still decays algebraically.Comment: 9 pages,10 figures,4 table
Effective bi-layer model Hamiltonian and density-matrix renormalization group study for the high-Tc superconductivity in LaNiO under high pressure
High-Tc superconductivity has been reported in the single crystal of
LaNiO under high pressure. Based on the electronic structure given
from the density functional theory calculations, we propose an effective
bi-layer model Hamiltonian including both and orbital
electrons of the nickel cations. The main feature of the model is that the
electrons form inter-layer -bonding and anti-bonding bands
via the apical oxygen anions between the two layers, while the
electrons hybridize with the electrons within each NiO plane.
The chemical potential difference of these two orbital electrons ensures that
the orbitals are close to half-filling and the
orbitals are near quarter-filling. The strong on-site Hubbard repulsion of the
orbital electrons gives rise to an effective inter-layer
antiferromagnetic spin super-exchange . Applying pressure can increase the
local coupling strength and self-dope holes on the orbitals with
the same amount of electrons doped on the orbitals
correspondingly. By performing numerical density-matrix renormalization group
calculations on a plaqutte ladder, we find that the charge densities of both
orbitals always have uniform distributions. But a spin-density-wave and a
spin-orbital density-wave are developed in the small limit. In the large
limit, both the spin and spin-orbital density waves get suppressed, and the
electron pairing instability emerges due to the formation of inter-layer
singlets of the electrons. The strongest pairing correlation is
given by the superconducting pair-density wave on the intra-layer vertical
bonds. Our numerical results have provided useful insights in
the high-Tc superconductivity in single crystal LaNiO under high
pressure.Comment: 6 pages, 4 figures; some typos are correcte
Probing Transverse Momentum Broadening via Dihadron and Hadron-jet Angular Correlations in Relativistic Heavy-ion Collisions
Dijet, dihadron, hadron-jet angular correlations have been reckoned as
important probes of the transverse momentum broadening effects in relativistic
nuclear collisions. When a pair of high-energy jets created in hard collisions
traverse the quark-gluon plasma produced in heavy-ion collisions, they become
de-correlated due to the vacuum soft gluon radiation associated with the
Sudakov logarithms and the medium-induced transverse momentum broadening. For
the first time, we employ the systematical resummation formalism and establish
a baseline calculation to describe the dihadron and hadron-jet angular
correlation data in and peripheral collisions where the medium effect
is negligible. We demonstrate that the medium-induced broadening and the so-called jet quenching parameter can be
extracted from the angular de-correlations observed in collisions. A
global analysis of dihadron and hadron-jet angular correlation data
renders the best fit for a
quark jet at RHIC top energy. Further experimental and theoretical efforts
along the direction of this work shall significantly advance the quantitative
understanding of transverse momentum broadening and help us acquire
unprecedented knowledge of jet quenching parameter in relativistic heavy-ion
collisions.Comment: 6 pages, 3 figure
Polymorphisms of CYP1A1 I462V and GSTM1 genotypes and lung cancer susceptibility in Mongolian
Aim: To study the genotype of cytochrome P450 1A1(CYP1A1) I462V and glutathions S-transferase M1( GSTM1) and the relationship of the genetic polymorphism of them with the susceptibility of lung cancer in Mongolia of China. 

Methods: Allele-specific PCR and a multiplex PCR were employed to identify the genotypes of I462V of CYP1A1 and GSTM1 in a case-control study of 210 lung cancer patients with bronchoscopy diagnosis and 210 matched controls free of malignancy.

Results: The frequencies of the variant CYP1A1(Val/Val) genotypes and GSTM1(-) in lung cancer groups were higher than that in control groups (15.24% vs 7.4% and 56.67% vs 40.95% ). The individuals who carried with CYP1A1(Val/Val) or GSTM1(-) genotype had a significantly higher risk of lung cancer, the OR is 2.56 and 1.89 respectively. Stratified histologically the relative risk increased to 2.6 - fold when the patients carried with two valine alleles than the ones carried one valine allele in cases of SCC. GSTM1(-) genotype is the risk factor of SCC (OR=2.39) and AC(OR=2.16). The presence of at least one Val allele of CYP1A1 and GSTM1(-), the risk of lung cancer was increased, the OR was 4.15 for one Val allele and GSTM1(-) and 2.67 for two Val alleles and GSTM1 Considering ages and smoking status, the risk of lung cancer increased when the age less than 50 who carried with CYP1A1 valine (one or two) alleles or the age during the 51 to 65 who carried with GSTM1(-) genotype. The light smokers with CYP1A1 valine alleles and GSTM1(-) have a high risk for lung cancer. No association was found between the light and heavy drinkers with the susceptibility of lung cancer and the genetic polymorphisms of CYP1A1 I462V and GSTM1(-). 

Conclusion: The valine allele of CYP1A1 was the risk factors of lung cancer especially for SCC and GSTM1(-) also was the risk factor of lung cancer and especially for SCC and AC of Mongolian, China. Light smoking has a influence each other with genotype of CYP1A1 I462V and GSTM1(-) and susceptibility of lung cancer. No relationship was found between the susceptibility of lung cancer and drinkers with genetic polymorphisms of CYP1A1 I462V and GSTM1(-). The influence of genotypes on the susceptibility of lung cancer may depend on the ages. There may be a synergetic interaction between CYP1A1 valine allele and GSTM1(-) genotypes on the elevated susceptibility of lung cancer. So do those genotypes with light smokers. Key words polymorphism; genotype; lung cancer; cytochrome P450;glutathione S-transferase Abbreviations: SCC, squamous cell carcinoma; AC, adenocarcinoma; SCLC, small cell lung cancer; LCLC, large cell lung cance
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