用第一级反应平面测量重离子碰撞中逐事件椭圆流涨落的一种方法

A new method is presented for measuring event-by-event fluctuations of elliptic flow (v₂) using first-order event planes. By studying the event-by-event distributions of v₂ observables and first-order event-plane observables, average flow 〈v₂〉and event-by-event fluctuations with respect to that average can be separately determined, making appropriate allowance for the effects of finite multiplicity. The relation of flow fluctuations to eccentricity fluctuations in the initial-state participant region, as well as detector acceptance effects, are discussed.     

Compressible Navier–Stokes Equations with Degenerate Viscosity Coefficient and Vacuum

 In this paper, we consider the compressible Navier–Stokes equations for isentropic flow of finite total mass when the initial density is either of compact or infinite support. The viscosity coefficient is assumed to be a power function of the density so that the Cauchy problem is well-posed. New global existence results are established when the density function connects to the vacuum states continuously. For this, some new a priori estimates are obtained to take care of the degeneracy of the viscosity coefficient at vacuum. We will also give a non-global existence theorem of regular solutions when the initial data are of compact support in Eulerian coordinates which implies singularity forms at the interface separating the gas and vacuum. Received: 28 September 2001 / Accepted: 6 May 2002 Published online: 4 September 2002     

Complete Sets of Polarization Observables in Electromagnetic Deuteron Breakup

 For deuteron photo- and electrodisintegration the selection of complete sets of polarization observables is discussed in detail by applying a recently developed new criterion for the check of completeness of a chosen set of observables. The question of ambiguities and their resolution by considering additional observables is discussed for a numerical example, for which the role of experimental uncertainties is also investigated. Furthermore, by inversion of the expressions of the observables as Hermitean forms in the t-matrix elements a bilinear term of the form can be given as a complex linear form in the observables from which an explicit solution for in terms of observables can be obtained. These can also be used to select sets of observables for the explicit representation of the t-matrix. Received May 15, 1999; accepted for publication August 30, 1999     

Forward jets and energy flow in hadronic collisions

We observe that at the Large Hadron Collider, using forward + central detectors, it becomes possible for the first time to carry out calorimetric measurements of the transverse energy flow due to “mini-jets” accompanying production of two jets separated by a large rapidity interval. We present parton-shower calculations of energy flow observables in a high-energy factorized Monte Carlo framework, designed to take into account QCD logarithmic corrections both in the large rapidity interval and for hard transverse momentum. Considering events with a forward and a central jet, we examine the energy flow in the interjet region and in the region away from the jets. We discuss the role of these observables to analyze multiple parton collision effects.     

Relations between polarization observables and complete sets for deuteron photodisintegration

The polarization observables for deuteron photodisintegration are given as Hermitean forms of theT-matrix elementst _i . By inversion we are able to express a given productt _i ^* t _j in terms of polarization observables. This allows (i) to derive linear relations between observables for unpolarized, circularly and linearly polarized photons, (ii) to construct explicitly complete sets of polarization observables, and (iii) to derive quadratic relations between observables.Supported by the Deutsche Forschungsgemeinschaft (SFB 201)     

Consistent treatment of relativistic corrections in deuteron photodisintegration in a one-pion-exchange model

Using a one-pion-exchange model for the nucleon-nucleon interaction the relativistic corrections to potential and to the electromagnetic operators are derived in a power expansion of (p/M). All corrections up to the order (p/M)³ are consistently included. Numerical results are shown for differential cross section and polarization observables for deuteron photodisintegration. A sizeable influence of relativistic effects on some observables is found even at low energies. A comparison of our operators with the expressions of other authors is given.Supported by Deutsche Forschungsgemeinschaft (SFB 201)     

The three-body force in the trinucleons

The status of three-body forces in nuclear physics within the context of the trinucleon system is reviewed. The theoretical approaches of the Hannover. Brazilian, Tuscon-Melbourne, and Urbana-argonne groups to modeling the three-nucleon force are outlined and compared. Results of numerical calculations based upon contemporaryNN forces alone plus those utilizing these three-body interactions are summarized for various bound-state observables and the Fourier transform of the charge density (the charge form factor in the impulse approximation) as well as selected continuum observables. Uncertainties in our experimental knowledge of theNN force, which significantly affect conclusions about the size of nuclear three-body force effects. are discussed.     

Sensitivity of the Low-Energy p-d Capture Observables to the Nucleon-Nucleon Force Components

 Polarization observables in low-energy proton-deuteron radiative capture have been calculated using the Bonn-B nucleon-nucleon potential. Their sensitivity to the changes of the nucleon-nucleon force components has been studied. Modifications of these forces, which drastically diminished the permanent discrepancy between the data and theory for the vector-analyzing power in low-energy nucleon-deuteron elastic scattering, have only small effects on the pd capture observables. Received May 26, 1999; accepted for publication June 30, 1999     

Interaction of heavy ions at the Large Hadron Collider (LHC)

The present-day understanding of the problem of the deconfinement of nuclear matter as applied to experiments that would study heavy ion collisions at the Large Hadron Collider (LHC) is discussed briefly. The elliptic energy flow, jet quenching, and the production of J/Ψ and Y quarkonia are appropriate observables here.     

相互作用突然开启后的反铁磁海森伯模型

本文以反铁磁海森伯模型为对象,设想了一个相互作用在t=0时刻开启的非平衡体系.在低温近似下,本文利用重整化群流方程方法讨论了该体系可观测量随时间的演化趋势.本文根据此类体系的特点,给出了获得算符时间演化形式的路径,并成功将其应用于本文所讨论的模型中.其中,本文着重介绍了如何在非平衡自旋体系中应用流方程方法,并利用该方法得到了随时间演化的基态磁化强度,同时论证了该方法处理此类系统的有效性.同时,在与平衡体系基态磁化强度的对比中,发现非平衡可观测量随时间震荡而无法收敛,这一点有别于相互作用突然开 关键词： 非平衡体系 反铁磁海森伯模型 流方程方法 磁化强度     

Impact of ${\cal O}(\alpha)$ radiative corrections on CC03 physics at LEP

In this work we report about the effect that the improved knowledge of electroweak radiative corrections, via the recent calculations of four-fermion processes with corrections in double pole approximation, has on WW physics at LEP2. Particular emphasis is given to the effects on differential distributions and their impact on the experimental observables. This study is based on generator comparisons using the new codes from the 2000 LEP2 Montecarlo workshop and allows new, important insights on the effects full radiative corrections have on W physics observables. The results presented here explain why it is so important to take these new calculations into account for precision measurements at LEP2. Received: 3 August 2001 / Revised version: 20 November 2001 / Published online: 18 January 2002     

Irreducible pionic effects in nucleon-deuteron scattering below 20 MeV

The consequences of a recently introduced irreducible pionic effect in low-energy nucleon-deuteron scattering are analyzed. Differential cross-sections, nucleon (vector) and deuteron (vector and tensor) analyzing powers, and four different polarization transfer coefficients are considered. This 3NF-like effect is generated by the pion exchange diagram in presence of a two-nucleon correlation and is partially cancelled by meson retardation contributions. Indications are provided that such type of effects are capable to selectively increase the vector (nucleon and deuteron) analyzing powers, while in the considered energy range they are almost negligible on the differential cross-sections. These indications, observed with different realistic nucleon-nucleon interactions, provide additional evidences that such 3NF-like effects have indeed the potential for solving the puzzle of the vector analyzing powers. Smaller but non-negligible effects are observed for the other spin observables. In some cases, we find that the modifications introduced by such pionic effects on these spin observables (other than the vector analyzing powers) are significant and interesting and could be observed by experiments. Received: 21 November 2001 / Accepted: 18 March 2002     

Complete Experiment for - and - Backward Elastic Scattering

. The problem of a complete experiment in backward elastic scattering of particles with spins of 1 and is considered. For the first time all possible effects induced by polarization of one or two initial and one final particles are touched upon. The minimal set of measurements allowing to reconstruct all of four amplitudes describing this process is proposed. Some observables are expected to be sensitive to hitherto largely unexplored deuteron properties, such as a possible P-wave component. The technique developed is a good tool to calculate easily impulse-approximation predictions for any observables. Accelerator facilities suitable for fulfilling the complete experiment are listed. Received May 30, 1997; accepted in final form October 8, 1997     

On the observables on quantum logics

Two postulates concerning observables on a quantum logic are formulated. By Postulate 1 compatibility of observables is defined by the strong topology on the set of observables. Postulate 2 requires that the range of the sum of observables ought to be contained in the smallestC-closed sublogic generated by their ranges. It is shown that the Hilbert space logicL(H) satisfies the two postulates. A theorem on the connection between joint distributions of types 1 and 2 on the logic satisfying Postulate 2 is proved.     

Some realizable joint measurements of complementary observables

Noncommuting quantum observables, if considered asunsharp observables, are simultaneously measurable. This fact is exemplified for complementary observables in two-dimensional state spaces. Two proposals of experimentally feasible joint measurements are presented for pairs of photon or neutron polarization observables and for path and interference observables in a photon split-beam experiment. A recent experiment proposed and performed by Mittelstaedt, Prieur, and Schieder in Cologne is interpreted as a partial version of the latter example.Work partly supported by the DFG, Bonn, and the BMFT, Bonn.Dedicated to Professor Ulrich Hauser on the occasion of his 60th birthday, November 1986.     

A Generalization of Entanglement to Convex Operational Theories: Entanglement Relative to a Subspace of Observables

We define what it means for a state in a convex cone of states on a space of observables to be generalized-entangled relative to a subspace of the observables, in a general ordered linear spaces framework for operational theories. This extends the notion of ordinary entanglement in quantum information theory to a much more general framework. Some important special cases are described, in which the distinguished observables are subspaces of the observables of a quantum system, leading to results like the identification of generalized unentangled states with Lie-group-theoretic coherent states when the special observables form an irreducibly represented Lie algebra. Some open problems, including that of generalizing the semigroup of local operations with classical communication to the convex cones case, are discussed. PACS: 03.65.Ud.     

Joint distributions of observables on quantum logics

A joint distribution of a set of observables on a quantum logic in a statem is defined and its properties are derived. It is shown that if the joint distribution exists, then the observables can be represented in the statem by a set of commuting operators on a Hilbert space.     

Quantum violation of noncontextuality for separable states using fewer measurement settings

The state-independent quantum violation of non-contextual realist models has been demonstrated both theoretically and experimentally for any two-qubit state using suitable choices of nine product observables and six different measurement setups. In this paper, for the separable states, a considerable simplification of such a demonstration is achieved by formulating a scheme that requires only five product observables and two different measurement setups.     

A detailed next-to-leading order QCD analysis of deeply virtual Compton scattering observables

We present a detailed next-to-leading order (NLO) leading twist QCD analysis of deeply virtual Compton scattering (DVCS) observables, for several different input scenarios, in the scheme. We discuss the size of the NLO effects and the behavior of the observables in skewedness , momentum transfer,t, and photon virtuality, . We present results on the amplitude level for unpolarized and longitudinally polarized lepton probes, and unpolarized and longitudinally polarized proton targets. We make predictions for various asymmetries and for the DVCS cross section and compare with the available data. Received: 30 November 2001 / Revised version: 12 February 2002 / Published online: 15 March 2002     

Lattice operations between observables in axiomatic quantum mechanics

Observables are treated as-homomorphisms of the Borel sets of the real line into an orthomodular-latticeL. By means of corresponding spectral-resolutions operations meet and join are defined between observables which endow the set of all observables with a lattice structure in caseL is-continuous and which give rise to lattices of observables in caseL is chosen arbitrarily and the observables commute.