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Jian Zhou

Publications and source records attributed to Jian Zhou.

At least 361 records · Page 20Linked to original sources
arXiv2009

Collins Fragmentation and the Single Transverse Spin Asymmetry

We study the Collins mechanism for the single transverse spin asymmetry in the collinear factorization approach. The correspondent twist-three fragmentation function is identified. We show that the Collins function calculated in this approach is universal. We further examine its contribution to the single transverse spin asymmetry of semi-inclusive hadron production in deep inelastic scattering and demonstrate that the transverse momentum dependent and twist-three collinear approaches are consistent in the intermediate transverse momentum region where both apply.

hep-ph↗
arXiv2009

Drell-Yan Lepton Pair Azimuthal Asymmetry in Hadronic Processes

We study the azimuthal asymmetry in the Drell-Yan lepton pair production in hadronic scattering processes at moderate transverse momentum region, taking into account the contributions from the twist-three quark-gluon correlations from the unpolarized hadrons. The contributions are found to dominate the asymmetry, and are not power suppressed by q_\perp/Q at small q_\perp where q_\perp and Q are the transverse momentum and invariant mass of the lepton pair. Accordingly, the Lam-Tung relation will be violated at this momentum region, and its violation depends on the twist-three functions. However, at large transverse momentum q_\perp\sim Q, the Lam-Tung relation still holds because all corrections are power suppressed by Λ^2/q_\perp^2\sim Λ^2/Q^2 where Λis the typical nonperturbative scale.

hep-ph↗
arXiv2008

QCD Evolution of the Transverse Momentum Dependent Correlations

We study the QCD evolution for the twist-three quark-gluon correlation functions associated with the transverse momentum odd quark distributions. Different from that for the leading twist quark distributions, these evolution equations involve more general twist-three functions beyond the correlation functions themselves. They provide important information on nucleon structure, and can be studied in the semi-inclusive hadron production in deep inelastic scattering and Drell-Yan lepton pair production in $pp$ scattering process.

hep-ph↗
arXiv2008

Arithmetic McKay correspondence

We propose an arithmetic McKay correspondence which relates suitably defined zeta functions of some Deligne-Mumford stacks to the zeta functions of their crepant resolutions. Some examples are discussed.

math.AG↗
arXiv2008

Crepant resolution conjecture in all genera for type A singularities

We prove an all genera version of the Crepant Resolution Conjecture of Ruan and Bryan-Graber for type A surface singularities. We are based on a method that explicitly computes Hurwitz-Hodge integrals described in an earlier paper and some recent results by Liu-Xu for some intersection numbers on the Deligne-Mumford moduli spaces. We also generalize our results to some three-dimensional orbifolds.

math.AG↗
arXiv2008

Hyperon Polarization in Unpolarized Scattering Processes

Transverse polarization in the Hyperon production in the unpolarized deep inelastic scattering and pp collisions is studied in the twist-three approach, considering the contribution from the quark-gluon-antiquark correlation distribution in nucleon. We further compare our results for deep inelastic scattering to a transverse momentum dependent factorization approach, and find consistency between the two approaches in the intermediate transverse momentum region. We also find that in pp collisions, there are only derivative terms contributions, and the non-derivative terms vanish.

hep-ph↗
arXiv2008

Single Spin Asymmetries in Heavy Quark and Antiquark Productions

The single transverse spin asymmetries in heavy quark and anti-quark production from the quark-antiquark annihilation channel contribution is studied by taking into account the initial and final state interactions effects. Because of the different color charges, the final state interaction effects lead to about a factor of 3 difference in the spin asymmetry for heavy quark over that for the anti-quark in the valence region of low energy pp collisions. The experimental study of this model-independent prediction shall provide a crucial test for the underlying mechanism for the single spin asymmetry phenomena.

hep-ph↗
arXiv2008

Multiple parton scattering in nuclei: gauge invariance

Within the framework of a generalized collinear factorization for multiple parton scattering in nuclear medium, twist-4 contributions to DIS off a large nucleus can be factorized as a convolution of hard parts and two-parton correlation functions. The hard parts for the quark scattering in the light-cone gauge correspond to interaction with a transverse (physical) gluon in the target, while they are given by the second derivative of the cross section with a longitudinal gluon in the covariant gauge. We provide a general proof of the equivalence of the hard parts in the light-cone and covariant gauge. We further demonstrate the equivalence in calculations of twist-4 contributions to semi-inclusive cross section of DIS in both lowest order and next leading order. Calculations of the nuclear transverse momentum broadening of the struck quark in the light-cone and covariant gauge are also discussed.

hep-ph↗
arXiv2008

The Transverse-momentum-dependent Parton Distribution Function and Jet Transport in Medium

We show that the gauge-invariant transverse-momentum-dependent (TMD) quark distribution function can be expressed as a sum of all higher-twist collinear parton matrix elements in terms of a transport operator. From such a general expression, we derive the nuclear broadening of the transverse momentum distribution. Under the maximal two-gluon correlation approximation, in which all higher-twist nuclear multiple-parton correlations with the leading nuclear enhancement are given by products of twist-two nucleon parton distributions, we find the nuclear transverse momentum distribution as a convolution of a Gaussian distribution and the nucleon TMD quark distribution. The width of the Gaussian, or the mean total transverse momentum broadening squared, is given by the path integral of the quark transport parameter $\hat q_F$ which can also be expressed in a gauge invariant form and is given by the gluon distribution density in the nuclear medium. We further show that contributions from higher-twist nucleon gluon distributions can be resummed under the extended adjoint two-gluon correlation approximation and the nuclear transverse momentum distribution can be expressed in terms of a transverse scale dependent quark transport parameter or gluon distribution density. We extend the study to hot medium and compare to dipole model approximation and ${\cal N}=4$ Supersymmetric Yang-Mills (SYM) theory in the strong coupling limit. We find that multiple gluon correlations become important in the strongly coupled system such as ${\cal N}=4$ SYM plasma.

hep-ph↗
arXiv2008

Spin-orbit interaction in Au structures of various dimensionalities

Variation of the geometrical and electronic properties of the gold materials in different dimensions has been investigated by $ab$ $initio$ method, taking into account the spin-orbit (SO) interaction. It is found that SO effects in different dimensional Au materials depend greatly on fundamental symmetry and dimensionality. For single walled gold nanotubes (SWGNTs), SO interaction decreases significantly the conducting channel number of achiral SWGNT (4, 0), and leads to spin splitting at Fermi level of chiral SWGNT, indicating that quasi-1D SWGNT can be a good candidate for the spin-electron devices. Furthermore, our results suggest that cage cluster might be synthesizable experimentally by taking gold tube structure as parent material.

cond-mat.mtrl-sci↗
arXiv2007

A Mathematical Theory of the Topological Vertex

We have developed a mathematical theory of the topological vertex--a theory that was original proposed by M. Aganagic, A. Klemm, M. Marino, and C. Vafa in hep-th/0305132 on effectively computing Gromov-Witten invariants of smooth toric Calabi-Yau threefolds derived from duality between open string theory of smooth Calabi-Yau threefolds and Chern-Simons theory on three manifolds.

math.AG↗
arXiv2007

Raman modes of the deformed single-wall carbon nanotubes

With the empirical bond polarizability model, the nonresonant Raman spectra of the chiral and achiral single-wall carbon nanotubes (SWCNTs) under uniaxial and torsional strains have been systematically studied by \textit{ab initio} method. It is found that both the frequencies and the intensities of the low-frequency Raman active modes almost do not change in the deformed nanotubes, while their high-frequency part shifts obviously. Especially, the high-frequency part shifts linearly with the uniaxial tensile strain, and two kinds of different shift slopes are found for any kind of SWCNTs. More interestingly, new Raman peaks are found in the nonresonant Raman spectra under torsional strain, which are explained by a) the symmetry breaking and b) the effect of bond rotation and the anisotropy of the polarizability induced by bond stretching.

cond-mat.mes-hall↗
arXiv2007

Radial-breathing-like phonon modes of double-walled carbon nanotubes

The radial-breathing-like phonon modes (RBLMs) of the double-walled carbon nanotubes are studied in a simple analytical model, in which the interaction force constants (FCs) can be obtained analytically from the continuous model. The RBLMs frequencies are obtained by solving the dynamical matrix, and their relationship with the tube radii can be obtained analytically, offering a powerful experimental tool for determining precisely the radii of the multi-walled carbon nanotubes.

cond-mat.mes-hall↗
arXiv2006

Electronic Structure and Linear Optical Properties of Sr$_{2}$CuO$_{2}$Cl$_{2}$ Studied from the First Principles Calculation

First-principles calculations with the full-potential linearized augmented plane-wave (FP-LAPW) method have been performed to investigate detailed electronic and linear optical properties of Sr$_{2}$CuO$_{2}$Cl$_{2}$, which is a classical low-dimensional antiferromagnet (AFM) charge transfer ({\it CT}) insulator. Within the local-spin-density approximation (LSDA) plus the on-site Coulomb interaction $U$ (LADA+$U$) added on Cu 3d orbitals, our calculated band gap and spin moments are well consistent with the experimental and other theoretical values. The energy dispersion relation agrees well with the angle resolved photoemission measurements. Its linear optical properties are calculated within the electric-dipole approximation. The absorption spectrum is found to agree well with the experimental result.

cond-mat.str-el↗
arXiv2005

Spin transfer and polarization of antihyperons in lepton induced reactions

We study the polarization of antihyperon in lepton induced reactions such as $e^+e^-\to\bar H+X$ and $l+p\to l'+\bar H+X$ with polarized beams using different models for spin transfer in high energy fragmentation processes. We compare the results with the available data and those for hyperons. We make predictions for future experiments.

hep-ph↗
arXiv2005

Cage-like Au32 detected by calculated optical spectroscopy

The optical absorptions of different Au32 isomers in the whole frequency range from the far-infrared (FIR) to near-ultraviolet (UV) have been calculated using the relativistic density-functional method in order to identify their geometrical structures. It is found that there exists a distinctive difference between the absorption spectra of the icosahedral cage-like Au32 and its amorphous isomers. The former shows significant absorption peaks in the visible and near-UV range, and a characteristic FIR-active mode at 46 cm-1, making it possible to be distinguished unambiguously from others, which suggests that the optical spectra can thus be used as an efficient experimental tool to detect the "golden fullerene".

cond-mat.mtrl-sci↗
arXiv2005

On a deformed topological vertex

We introduce a deformed topological vertex and use it to define deformations of the topological string partition functions of some local Calabi-Yau geometries. We also work out some examples for which such deformations satisfy a deformed Gopakumar-Vafa integrality and can be identified with the equivariant indices of some naturally defined bundles on the framed moduli spaces.

math.AG↗