共查询到20条相似文献,搜索用时 15 毫秒
1.
P. J. Mulders 《Pramana》2009,72(1):83-95
We discuss the treatment of intrinsic transverse momenta in high energy scattering processes. Within the field theoretical
framework of QCD, the process is described in terms of correlators containing quark and gluon fields. The correlators, parametrized
in terms of distribution and fragmentation functions, contain matrix elements of nonlocal field configurations requiring a
careful treatment to assure colour gauge invariance. It leads to nontrivial gauge links connecting the parton fields. For
the transverse momentum-dependent correlators the gauge links give rise to time reversal odd phenomena, showing up as single
spin and azimuthal asymmetries. The gauge links, arising from multi-gluon initial and final state interactions, depend on
the colour flow in the process, challenging universality.
相似文献
2.
Asmita Mukherjee R. Basu H. Dahiya L. Gamberg R. Godbole S. Gupta M. C. Kumar L. Magnea P. Mathews N. Mathur A. Mukherjee P. J. Mulders V. Ravindran A. Tripathi 《Pramana》2009,72(1):277-283
This is the report of the QCD working sub-group at the Tenth Workshop on High Energy Physics Phenomenology (WHEPP-X).
相似文献
3.
Detailed predictions of QCD on transverse momentum distributions of jets in leptoproduction are presented. The average p⊥2 is found to be asymptotically proportional to W2 (the hadronic invariant mass squared) with a coefficient function that depends little on x and y. Contributions from gluons in the nucleon are relatively smaller than for σL/σT. 相似文献
4.
Transverse momentum and transverse mass distributions of charged hadrons produced in Au--Au collisions at high energies
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The transverse momentum distribution and the transverse mass distribution of charged hadrons produced in nucleus nucleus collisions at high energies are described by using a two-cylinder model. The results calculated by the model are compared and found to be in agreement with the experimental data of the STAR and E895 Collaborations, measured in A~Au collisions at the relativistic heavy ion collider (RHIC) and alternating-gradient synchrotron (AGS) energies, respectively. In the energy range concerned, the excitation degree of emission source close to the central axis of cylinders increases obviously with the collision centrality and incident energy increasing, but it does not show any obvious change with the increase of the (pseudo)rapidity in central collisions. The excitation degree of emission source close to the side-surface of cylinders does not show any obvious change with the collision centrality, the (pseudo)rapidity, and the incident energy increasing. 相似文献
5.
根据电子自旋轨道耦合对自旋极化弛豫影响的DP机理进一步导出了半导体中电子自旋弛豫与动量弛豫及载流子浓度的关系,并采用飞秒抽运探测技术在室温下测量AlGaAs/GaAs 多量子阱中载流子浓度在 1×1017—1×1018cm-3范围内,电子自旋弛豫时间由58ps增加至82 ps的变化情况,与理论计算值符合,说明了随着载流子浓度的增加,载流子间的频繁散射加速了电子动量驰豫,减弱了电子自旋轨道耦合作用,从而延长了电子自旋寿命.
关键词:
电子自旋轨道耦合
电子自旋弛豫和动量弛豫
飞秒光谱技术 相似文献
6.
WANG Gang 《Chinese Journal of Lasers》1994,3(2):137-142
IntrinsicangularmomentuminHMOWANGGang(PhysicsDepartment,UniversityofElectronicScienceandTechnologyofChina,Chengdu610054,China... 相似文献
7.
The transverse momentum distributions of final-state particles produced in nucleus-nucleus (AA), proton-nucleus (pA), and proton-proton (pp) collisions at high energies are investigated using a multisource ideal gas model. Our calculated results show that the contribution of hard emission can be neglected in the study of transverse momentum spectra of charged pions and kaons produced in Cu-Cu collisions at √sNN=22.5 GeV. And if we consider the contribution of hard emission, the transverse momentum spectra of p and p produced in Cu-Cu collisions at √sNN=22.5 GeV, Ks0 produced in Pb-Pb collisions at 158 A GeV, J/ψ particles produced in p-Pb collisions at 400 GeV and π+ , K+, p produced in proton-proton collisions at √s=200 GeV, can be described by the model, especially in the tail part of spectra. 相似文献
8.
We briefly describe motivations for studying transverse lattice QCD. Presence of constraint equation for fermion field on
the light front allows different methods to put fermions on a transverse lattice. We summarize our numerical investigation
of two approaches using (a) forward and backward derivatives and (b) symmetric derivatives. 相似文献
9.
A general analysis of the Slavnov-Taylor identity connecting the triple gluon and ghost-ghost-gluon vertices and its consequences
for two momentum subtraction (symmetric and asymmetric) renormalization schemes are given. It is shown that in the asymmetric
scheme proposed in this paper the relation
follows directly from the identity for a simple and natural definition of the renormalization constants. Explicit one-loop
expressions for the renormalization constants
in an arbitrary covariant gauge, including quark masses are given in support of the general analysis. 相似文献
10.
《Zeitschrift fur Physik C Particles and Fields》1997,73(3):421-432
Using data obtained with the ALEPH detector at the Z resonance, a measure based on transverse momentum is shown to exhibit a correlation between the two halves of a hadronic event which cannot be explained by energy-momentum conservation, flavour conservation, the imposition of an event axis or imperfect event reconstruction. Two possible interpretations based on existing Monte Carlo models are examined: a) ARIADNE, with the correlation forming early in the parton shower and with the transition from partons to hadrons playing only a minor part; b) JETSET, with the correlation forming at the fragmentation stage. A correlation technique based on a jet cluster analysis is used to make a comparison of the models with the data. It is concluded that both non-perturbative and perturbative effects make important contributions to the observed correlation. 相似文献
11.
12.
We report results on event-by-event fluctuations in mean transverse momentum in AuAu collisions at
GeV measured by the STAR experiment at RHIC. The dynamical fluctuations,
is found to be about 1.2 ±02% of the mean transverse momentum for particles in pseudo-rapidity range of −0.5 < η < 0.5 and
for the top 6% central collisions. 相似文献
13.
We extend the Gyulassy–Levai–Vitev reaction operator approach to multiple elastic scattering of fast partons traversing dense nuclear matter to take into account the leading power corrections due to the medium recoil and to derive the change in the partons' longitudinal momentum. We employ a boost-invariant formalism to generalize previous treatments of the problem, which were specific to the target rest frame. We apply the transverse momentum diffusion results in a simple analytic model to evaluate the broadening of the back-to-back di-hadron correlation function in d+Au reactions. 相似文献
14.
15.
We have observed sub-Poissonian spin correlations generated by collisionally induced spin mixing in a spin-1 Bose-Einstein condensate. We measure a quantum noise reduction of -7 dB (-10 dB corrected for detection noise) below the standard quantum limit for the corresponding coherent spin states. The spin fluctuations are detected as atom number differences in the spin states using fluorescent imaging that achieves a detection noise floor of 8 atoms per spin component for a probe time of 100 μs. 相似文献
16.
Y.Miyachi 《中国物理C(英文版)》2010,34(9)
The HERMES measured azimuthal amplitudes of cross sections and their transverse target single spin asymmetries for hadron productions in semi-inclusive deep inelastic scattering.From the extracted amplitudes,novel patton distribution functions can be studied.The recent results related to Sivers and Boer-Mulders distribution functions are discussed. 相似文献
17.
A scheme to calculate the electron momentum density in simple liquid metals, with the effect ofboth electron correlations and ionic potentials included, is given. This scheme is applied to the case of liquid aluminium. The
results are substantially different from calculations considering only the ion potentials, and also from the results for a
homogeneous electron gas of corresponding density. 相似文献
18.
Y. Miyachi 《中国物理 C》2010,34(9):1494-1497
The HERMES measured azimuthal amplitudes of cross sections and their transverse target single spin asymmetries for hadron productions in semi-inclusive deep inelastic scattering.From the extracted amplitudes,novel parton distribution functions can be studied.The recent results related to Sivers and Boer-Mulders distribution functions are discussed. 相似文献
19.
20.
运用微扰QCD讨论了重离子碰撞中大横动量轻子对的分布, 计算了Au-Au碰撞中两个部分子产生的轻子对的贡献。引入了轻子对产生的直接单光子过程和分解单光子过程。大横动量情况下的所有过程都包括在内, 而且考虑了核遮蔽效应和同位旋效应, 作为QGP背景的双轻子信号有了一个好的修正。The large transverse momentum distribution of lepton pairs produced in heavy-ion collisions has been studied, making use of the perturbative QCD. The contribution of the two parton production process into lepton pairs in Au Au collisions is calculated. Lepton pair production with the direct single photon process and the resolved single photon process are introduced. We believe that the photon processes are significant. The complete processes at large transverse momentum are included, and moreover, the effect of shadowing and isospin of nucleus are also considered in heavy ion collisions. Dilepton signals to regard the background of QGP have a good correction. 相似文献