Perturbative QCD description of multiparticle correlations in quark and gluon jets

The QCD evolution equations in Modified Leading Log Approximation for the factorial moments of the multiplicity distribution in quark and gluon jets are numerically solved with initial conditions at threshold by fully taking into account the energy conservation law. After applying Local Parton Hadron Duality as hadronization prescription, a consistent quantitative description of available experimental data for factorial cumulants and factorial moments of arbitrary order and for their ratio both in quark and gluon jets and in $e^+e^-$ annihilation is achieved.Comment: LaTeX, 15 pages, 3 figures, typos corrected in the labels and caption of Figure

How Elitism Undermines the Study of Voter Competence

A form of elitism undermines much writing on voter competence. The elitist move occurs when an author uses a self-serving worldview as the basis for evaluating voters. Such elitism is apparent in widely cited measures of “political knowledge” and in common claims about what voters should know. The elitist move typically limits the credibility and practical relevance of the analysis by leading writers to draw unreliable conclusions about voter competence. I propose a more constructive way of thinking about what voters know. Its chief virtue is its consistency with basic facts about the relationship between information and choice.information; search; competence; political knowledge; public policy

Necessary Conditions for Improving Civic Competence: A Scientific Perspective

Many attempts to increase civic competence are based on premises about communication and belief change that are directly contradicted by important insights from microeconomic theory and social psychology. At least two economic literatures are relevant to my effort to improve matters. One is the literature on strategic communication, which includes Spence (1974), Crawford and Sobel (1982), Banks (1991), and Lupia and McCubbins (1998). The other is the literature on mechanism design, which includes Green and Laffont (1977), Myerson (1983) and Palfrey (1992). While both literatures have the potential to convey important insights, many scholars and practitioners do not yet see a need for such insights. This paper lays such a foundation. It explains how greater attention to basic scientific principles can help people who want to increase civic competence use the generosity of donors and the hard work of well-intentioned citizens more effectively. The paper continues as follows. First, I discuss the topic of competence more precisely. Then, I introduce the necessary conditions for increasing civic competence described above. Next, I describe implications and applications of these conditions – focusing in this paper on the growing contention that deliberation is an effective way to increase civic competence. Applying the necessary conditions to this topic reveals a need to revise and clarify common expectations about what deliberation can accomplish. A brief concluding section follows.incomplete information, strategic communication, learning, behavioral economics,

Unified QCD Description of Hadron and Jet Multiplicities

The evolution equation for parton multiplicities in quark and gluon jets which takes into account the soft gluon interference is solved numerically using the initial conditions at threshold. If the k_T-cutoff Q_c is lowered towards the hadronic scale Q_0 of a few hundred MeV, the jets are fully resolved into hadrons. Both hadron and jet multiplicities in e+e- annihilation are well described with a common normalization. Evidence is presented within this perturbative approach that the coupling \alpha_s(k_T) rises by an order of magnitude when approaching the low energy region. The ratio of hadron multiplicities in gluon and quark jets is found smaller than in previous approximate solutions of the evolution equation.Comment: LaTeX, 15 pages, 3 figure

Hadron multiplicity as the limit of jet multiplicity at high resolution

Recently exact numerical results from the evolution equation for parton multiplicities in QCD jets have been obtained. A comparison with various approximate results is presented. A good description is obtained not only of the jet multiplicities measured at LEP-1 but also of the hadron multiplicities for $cms$ energies above 1.6 GeV in \epem annihilation. The solution suggests that a final state hadron can be represented by a jet in the limit of small (nonperturbative) $k_\perp$ cut-off $Q_0$. In this description using as adjustable parameters only the QCD scale $\Lambda$ and the cut-off $Q_0$, the coupling $\alpha_s$ can be seen to rise towards large values above unity at low energies.Comment: LaTex, 4 pages, 2 figures, presented at HEP Int. Euroconf. on Quantum Chromodynamics, Montpellier, July 199

Low and High Energy Limits of Particle Spectra in QCD Jets

Charged particle energy spectra in e+e- annihilation are compared with the analytical predictions from the QCD evolution equation in the Modified Leading Log Approximation. With the nonperturbative initial condition shifted down to threshold as suggested by the Local Parton Hadron Duality picture a good description of the data from the lowest up to highest available energies results. The two essential parameters in this approach are determined from a moment analysis. The sensitivity of the fit to the running of alpha_s and to the number of active flavours (including a light gluino) is demonstrated. For very high energies the theory predicts a scaling behaviour in certain rescaled variables (``zeta-scaling''). The data show an approximate behaviour of this type in the present energy range and come close to the predicted asymptotic scaling function for the small particle energies.Comment: LaTeX2e, 45 pages, 12 figure

Lost in Translation: Social Choice Theory is Misapplied Against Legislative Intent

Several prominent scholars use results from social choice theory to conclude that legislative intent is meaningless. We disagree. We support our argument by showing that the conclusions in question are based on misapplications of the theory. Some of the conclusions in question are based on Arrow\u27s famous General Possibility Theorem. We identify a substantial chasm between what Arrow proves and what others claim in his name. Other conclusions come from a failure to realize that applying social choice theory to questions of legislative intent entails accepting assumptions such as legislators are omniscient and legislators have infinite resources for changing law and policy. We demonstrate that adding more realistic assumptions to models of social choice theory yields very different theoretical results-including ones that allow for meaningful inferences about legislative intent. In all of the cases we describe, important aspects of social choice theory were lost in the translation from abstract formalisms to real political and legal domains. When properly understood, social choice theory is insufficient to negate legislative intent

What Citizens Know Depends on How You Ask Them: Political Knowledge and Political Learning Skills

Surveys provide widely-cited measures of political knowledge. Do unusual aspects of survey interviews reduce their relevance? To address this question, we embedded a set of experiments in a representative survey of over 1200 Americans. A control group answered political knowledge questions in a typical survey context. Respondents in treatment groups received the same questions in different contexts. One group received a monetary incentive for answering questions correctly. Others were given more time to answer the questions. The treatments increase the number of correct answers by 11-24 percent. Our findings imply that conventional knowledge measures confound respondents’ recall of political information and their motivation to engage the survey question. The measures also provide unreliable assessments of respondents’ abilities to access information that they have stored in places other than their immediately available memories. As a result, existing knowledge measures likely underestimate peoples’ capacities for informed decision making.political knowledge; economic knowledge; experimental economics; incentives; survey