终于看到希格斯玻色子衰变成底夸克

50年前,Steven Weinberg和Abdus Salam分别提出了弱相互作用理论。传递弱相互作用的W和Z玻色子必须具有大质量才能解释弱力的短程性。为引入这些质量,Weinberg和Salam 假定W和Z玻色子通过与一种场相互作用而获得质量。这种场是Peter Higgs (希格斯)等早些时候提出的。“希格斯场”的存在意味着希格斯玻色子的存在,经过几十年的寻找,最终在强子对撞机LHC上工作的ATLAS和CMS合作组于 2012年在质子—质子对撞产生的碎片中发现了这种粒子。     

“Gluelump” spectrum and adjoint source potential in lattice QCD3

We calculate the potential between “quarks” which are in the adjoint representation of SU(2) color in the three-dimensional lattice theory. We work in the scaling region of the theory and at large quark separations R. We also calculate the masses M_Qg of color-singlet bound states formed by coupling an adjoint quark to adjoint glue (“gluelumps”). Good scaling behavior is found for the masses of both magnetic (angular momentum J = 0) and electric (J = 1) gluelumps, and the magnetic gluelump is found to be the lowest-lying state. It is naively expected that the potential for adjoint quarks should saturate above a separation R_scr where it becomes energetically favorable to produce a pair of gluelumps. We obtain a good estimate of the naive screening distance R_scr. However we find little evidence of saturation in the potential out to separations R of about 1.5R_scr.     

A multifractal analysis of equilibrium measures for conformal expanding maps and Moran-like geometric constructions

In this paper we establish the complete multifractal formalism for equilibrium measures for Hölder continuous conformal expanding maps andexpanding Markov Moran-like geometric constructions. Examples include Markov maps of an interval, beta transformations of an interval, rational maps with hyperbolic Julia sets, and conformal toral endomorphisms. We also construct a Hölder continuous homeomorphism of a compact metric space with an ergodic invariant measure of positive entropy for which the dimension spectrum is not convex, and hence the multifractal formalism fails.     

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.     

CAUSAL DOMAIN OF MINKOWSKI-SPACETIME TANGENT BUNDLE

The geometry of the causal domain of the spacetime tangent bundle is examined for Finslerian quantum fields in Minkowski spacetime. The Planck-scale structure of the boundary of the causal domain is elaborated. The geometry indicates that at the Planck scale, causal connectivity of Finslerian quantum fields may occur between spacelike separated points, and also at larger scales for extremely large relative four-velocities.     

The possibly trapped excess free volume

Excess free-volume trapping incurred by quenching has been quantified for atactic polystyrenes with different molecular weights. As the initial temperature (T₀) is elevated from the glass transition (T_g), the increment in excess free-volume trapping first responds sharply, then becomes sluggish, and finally levels off. Molecular weight increase shifts the isochronal curves to a higher temperature region, which coincides with the isochronal change in glass transition temperature (T_g ^t)- As the isochronal curves are superposed to form a master curve, the mechanism of excess free-volume trapping is essentially controlled by T₀, from which the conformational structures of molecules are determined prior to quenching, rather than by the final aging temperature. In order for this superposition to occur, conceivably, the content of excess free volume trapped in the glassy state has to be fairly constant throughout all temperatures below T_g. Consequently, this study does not support the existence of an underlying equilibrium extrapolated from the rubber state.     

Coupling of the Double Bond Stretching Vibration in Divinyl Ethers

Abstract

Examination of the Infrare and Raman spectra of cis, cis-dipropenyl ether (which was produced by isomerization of diallyl ether) has produced evidence for strong vibrational coupling between the two double-bonds. This ether has strong bands it 1655 cm^?1 in the infrared and at 1691 cm^?1 in the Raman. The 1658 cm^?1 band in the Raman is about 10 fold less intense than the strong polarised band. Thus it appears reasonable to associate the strong IR and Raman bands with the asymmetric and symmetric vibrations shown.     

Electric field of a buried interfacial region measured by positron-lifetime spectroscopy

Positrons from a radioactive source are implanted into a reverse-biased metal–semiconductor contact and are drifted back towards the contact by the internal electric field where they trap into voids and annihilate. The electric field dependent interface annihilation fraction is monitored by way of the intensity of the long (∼400–500 ps) void lifetime component using positron-lifetime spectroscopy. Unlike previous analyses of such systems a numerical model involving positron drift, annihilation and trapping into the interfacial state has been constructed to describe the positron dynamics in the presence of the non-uniform junction electric field. The use of the positron-lifetime technique in probing the internal electric field at buried contacts is thus demonstrated. Results obtained using the numerical method for the Au, Al and Ni/Semi-Insulating (SI)-GaAs contact systems are found to be consistent with the findings of previous studies on the Au/SI-GaAs system. Received: 29 November 2000 / Accepted: 26 February 2001 / Published online: 25 July 2001     

Are Real-Time Displays of Benefit in the Singing Studio? An Exploratory Study

This article reports on an exploratory research project to evaluate the usefulness or otherwise of real-time visual feedback in the singing studio. The primary purpose of the work was not to optimize the technology for this application, but to work alongside teachers and students to study the impact of real-time visual feedback technology use on the students' learning experiences. An action research methodology was used to explore the benefit of real-time displays over an extended period. The experimental phase of the work was guided by a Liaison Panel of teachers and academics in the areas of singing, pedagogy, voice science, speech therapy, and linguistic science. Qualitative data were collected from eight students working with two professional singing teachers. The teachers and students acted as co-researchers under the action research paradigm. Teachers and students alike kept journals of their teaching and learning experiences. Singing lessons were observed regularly by the research team, coded for teacher and student behaviors, and all co-researchers were interviewed at the mid- and endpoint of the project. The use of technology had a positive impact on the learning process, and this is evidenced through case study data.