Novel mechanisms of baryon number flow over large rapidity gap

It is shown that slow valence quark in the wave function of high energy proton can fragment into a baryon if the fast diquark-spectator is destroyed, i.e. is turned from the antitriplet to the sextet colour state. We estimated the cross section of the baryon number flow to the central rapidity region using the perturbative QCD. It depends on the rapidity gap Δy as exp (-Δy/2) and nicely agrees with the data at ISR energies, There exists also an intriguing possibility to transfer baryon number by means of gluonic exchanges only. This contribution does not depend on rapidity at all and becomes sizable in TeV energy region. We propose also new mechanisms for baryonantibaryon production from vacuum, transfer of polarization over large rapidity intervals, and nuclear stopping power.     

Charge transfer and rapidity gap analysis inp(π+)n interactions at 195GeV/c

We present charge transfer probabilities between CM hemispheres inpn and π⁺ n interactions at 195 GeV/c. The relative probabilities for charge exchanges |ΔQ|>1 as a function of rapidity gap length,r, are given. Both results are compared with those of π^? p interactions at 200GeV/c. The average ofr, viz. <r>, is given as a function of the gap number and of ΔQ for various multiplicities, and the reduced average gap lengths <r>/y _max forpn interactions are compared with data at a lower energy.     

The gap survival probability and diffractive dissociation

We study the survival probability for rapidity gaps in a model which includes diffractive dissociation. A Good-Walker model implementation of the minijet model, which consistently includes inelastic diffraction, predicts a much larger survival probability than previous calculations.     

Energy dependence of gap survival probability and antishadowing

We discuss the energy dependence of the gap survival probability which follows from the rational form of the amplitude unitarization. In contrast to the eikonal form of unitarization which leads to a decreasing energy dependence of the gap survival probability, we predict a non-monotonous form for this dependence.Received: 8 April 2004, Revised: 31 October 2004, Published online: 25 January 2005     

Virtuality evolution and rapidity structure of a simplified parton shower

We have studied transverse momentum distributions for exclusive ⁰ muoproduction on protons and heavier nuclei at 2Q ²<25>². TheQ ² dependence of the slopes of thep _t ² andt distributions is discussed. The influence of the non-exclusive background is investigated. Thep _t ² -slope for exclusive events is 4.3±0.6±0.7 GeV^–2 at largeQ ². Thep _t ² spectra are much softer than inclusivep _t ² spectra of leading hadrons produced in deep inelastic scattering.Supported by Bundesministerium für Forschung und Technologie     

Clan structure and intermittency in proton-nucleus interactions at high energy

In this paper we examine the similarity between clan structure and self-similar cascading in high energy proton-nucleus interactions at 70 GeV/c in emulsion. The investigation shows that the negative bionomial fitting parameterk can be used for the evaluation of factorial moments in intermittency studies and that these exhibit similar behaviour with those derived from nonstatistical procedure. The results of our study signify compatibility between clan cascading and self-similar cascading in soft hadroization processes.     

The rapidity structure of Mach cones and other large angle correlations in heavy-ion collisions

The pattern of angular correlations of hadrons with a (semi-)hard trigger hadron in heavy-ion collisions has attracted considerable interest. In particular, unexpected large angle structures on the away side (opposite to the trigger) have been found. Several explanations have been brought forward, among them Mach shockwaves and Cherenkov radiation. Most of these scenarios are characterized by radial symmetry around the parton axis, thus angular correlations also determine the rapidity dependence of the correlation. If the observed correlations are remnants of an away side parton after interaction with the medium created in the collision, pQCD allows to calculate the distribution P(y)$P(y)$ of the away side partons in rapidity. The measured correlation then arises as a folding of P(y)$P(y)$ and the rapidity structure of the correlation taking into account the detector acceptance. This places non-trivial and rather stringent constraints on the underlying scenario. We investigate these dependences and demonstrate that Mach shockwaves survive this folding procedure well whereas Cherenkov radiation scenarios face new challenges.     

混合压电分流电路作用下声子晶体杆振动带隙结构分析

对于电阻电感(RL)及负阻抗变换器(NIC)混合压电分流电路分别采用紧密及间隔排列方式进行带隙结构计算,并且针对分流电路中电阻、电感及电容对于局域共振带隙的影响进行研究。采用传递矩阵法建立了压电分流电路作用下声子晶体杆带隙分析的理论模型,并运用MATLAB语言对带隙结构进行编程仿真计算。通过电阻、电感、电容参数的匹配及电路不同排列方式的对比,最终得到了在混合间隔压电分流电路作用下宽度为13 kHz的带隙,并对振动控制系统稳定性进行了分析。研究结果表明:采用混合压电分流电路会对杆件带隙结果产生影响,且采用压电片间隔排列的方式会使带隙宽度明显扩大。     

Band gap structure analysis of phononic crystal rods with hybrid shunted piezoelectric patches

The band gap structures by arranging hybrid shunted piezoelectric materialswith resistance inductive(RL) circuit and negative impedance converter(NIC) closely and at intervals are presented.The theoretical model is built using transfer matrix method.Then the MATLAB computing language is utilized to simulate the band gap structures.Meanwhile,the effects of the resistance,inductance and capacitance on the local resonant gap are studied.By comparing different combinations of resistance,inductance and capacitance as well as different arrangement of circuits,a 13 kHz band gap is reached under the effect of arranging hybrid periodic shunted piezoelectric patches at intervals and the stability of the system is also analyzed.It is proved that utilizing hybrid shunted piezoelectric patches would have a clear impact on the band gap structure of phononic crystal rods.Moreover,the band gap would be clearly enlarged by arranging hybrid piezoelectric patches at intervals.     

混合压电分流电路作用下声子晶体杆振动带隙结构分析

对于电阻电感(RL)及负阻抗变换器(NIC)混合压电分流电路分别采用紧密及间隔排列方式进行带隙结构计算,并且针对分流电路中电阻、电感及电容对于局域共振带隙的影响进行研究。采用传递矩阵法建立了压电分流电路作用下声子晶体杆带隙分析的理论模型,并运用MATLAB语言对带隙结构进行编程仿真计算。通过电阻、电感、电容参数的匹配及电路不同排列方式的对比,最终得到了在混合间隔压电分流电路作用下宽度为13 kHz的带隙,并对振动控制系统稳定性进行了分析。研究结果表明:采用混合压电分流电路会对杆件带隙结果产生影响,且采用压电片间隔排列的方式会使带隙宽度明显扩大。     

Multiplicity distributions and long range rapidity correlations

The physics of the initial conditions of heavy ion collisions is dominated by the nonlinear gluonic interactions of QCD. These lead to the concepts of parton saturation and the Color Glass Condensate (CGC). We discuss recent progress in calculating multigluon correlations in this framework, prompted by the observation that these correlations are in fact easier to compute in a dense system (nucleus–nucleus) than a dilute one (proton–proton).     

Hidden asymmetry and long range rapidity correlations

Interpretation of long-range rapidity correlations in terms of the fluctuating rapidity density distribution of the system created in high-energy collisions is proposed. When applied to recent data of the STAR Collaboration, it shows a substantial asymmetric component in the shape of this system in central Au–Au collisions, implying that boost invariance is violated on the event-by-event basis even at central rapidity. This effect may seriously influence the hydrodynamic expansion of the system.     

Clan structure in high energypn,pp andp\bar p interactions

We have analysed ourpn data at 400 GeV (corresponding to a centre-of-mass energy \(\sqrt s = 27.5\) GeV) together with otherpp and \(p\bar p\) data in the centre of mass energy range 11.5–900 GeV. The fits of all these distributions to a negative binomial distribution are performed. The variations in the fitted average multiplicity and in the inverse of the fitted parameterk are obtained with respect to the centre of mass energy. An assessment of the single diffractive component in the multiplicity distribution is made and its variation with the centre of mass energy discussed. The average number of clans and the average charged multiplicity per clan are determined and the centre of mass energy dependences shown.