Superinsulator as a phase of bi-particle localized states

We propose a physical picture of superinsulator observed recently in experiments with superconducting films in a magnetic field. On the basis of previous numerical studies we argue that a moderate attraction creates bi-particle localized states at intermediate disorder strength when noninteracting electron states are delocalized and metallic. Our present numerical study show that such localized pairs are broken by a static electric field which strength is above a certain threshold. We argue that such a breaking of localized pairs by a static field is at the origin of superinsulator breaking with a current jump observed experimentally above a certain critical voltage.     

Supersymmetry beyond minimal flavor violation

We review the sources and phenomenology of non-minimal flavor violation in the MSSM. We discuss in some detail the most important theoretical and experimental constraints, as well as promising observables to look for supersymmetric effects at the LHC and in future experiments. We emphasize the sensitivity of flavor physics to the mechanism of supersymmetry breaking and to new degrees of freedom present at fundamental scales, such as the grand unification scale. We include a discussion of present data that may hint at departures from the standard model.     

Wave breaking in Boussinesq models for undular bores

A nonlinear dispersive model equation is used to study the onset of breaking in long waves behind the front of an undular bore. According to experiments conducted by Favre (1935) [1], weak bores have a smooth, but oscillatory structure, with undulations appearing behind the bore front. With increasing bore strength, the amplitude of these oscillations grows until one or several of them start breaking. The change in type from the purely undular bore occurs at a sharply defined depth ratio which is under review in this article. A convective breaking criterion is put forward, and numerical computations are used to compare the predictions of this model to Favre?s wavetank experiments. It appears that the numerical results underpredict the appearance of breaking waves, but are in good qualitative agreement with the experiments. The results are interpreted with the aid of exact solitary-wave solutions, and it is found that the transition from purely undular to breaking bore may be recast with the help of a breaking criterion for solitary waves.     

On the observation of decoherence with a movable mirror

Following almost a century of debate on possible “independent of measurement" elements of reality, or “induced" elements of reality - originally invoked as an ad-hoc collapse postulate, we propose a novel line of interference experiments which may be able to examine the regime of induced elements of reality. At the basis of the proposed experiment, lies the hypothesis that models of “induced" elements of reality should exhibit symmetry breaking within quantum evolution. The described symmetry experiment is thus aimed at being able to detect and resolve spatial symmetry breaking signatures. The proposed experiment stands at the edge of present day technological abilities and will be, so we believe, realizable in the near future. Received 2 December 1999 and Received in final form 6 April 2000     

Signals of spontaneous R parity breaking at LEP and at a linear collider

We study the production of neutralinos and charginos at LEP and at a linear collider in the case of spontaneously broken R-parity. We first investigate the constraints on the single neutralino and chargino production from the LEP 1 experiments, and then we consider the production at LEP 2 and at a linear collider. We concentrate on the supersymmetric model, where the spontaneous R-parity breaking is inevitable and is associated with the breaking of the LR-symmetry. Received: 26 February 1998 / Published online: 9 April 1998     

Phenomenology of the production,decay, and detection of new hadronic states associated with supersymmetry

Supersymmetric theories involve spinorial partners for the gluons of QCD. If the symmetry breaking is such that they are massless or light, they probably combine with quarks to form families of new, relatively low-lying hadrinic states, which decay into ordinary hadrons and a new, neutrino-like particle. We discuss how present experiments can put limits on their production.     

Spontaneous breaking of spatial and spin symmetry in spinor condensates

Parametric amplification of quantum fluctuations constitutes a fundamental mechanism for spontaneous symmetry breaking. In our experiments, a spinor condensate acts as a parametric amplifier of spin modes, resulting in a twofold spontaneous breaking of spatial and spin symmetry in the amplified clouds. Our experiments permit a precise analysis of the amplification in specific spatial Bessel-like modes, allowing for the detailed understanding of the double symmetry breaking. On resonances that create vortex-antivortex superpositions, we show that the cylindrical spatial symmetry is spontaneously broken, but phase squeezing prevents spin-symmetry breaking. If, however, nondegenerate spin modes contribute to the amplification, quantum interferences lead to spin-dependent density profiles and hence spontaneously formed patterns in the longitudinal magnetization.     

The laser polarization as control parameter in the formation of laser-induced periodic surface structures: Comparison of numerical and experimental results

Considering self-organized surface pattering upon multi-pulse femtosecond laser irradiation, in particularly the strong dependence of ripples orientation on the laser polarization, we present numerical simulations from an adopted surface erosion model and compare the result to our experimental data on laser-induced nanostructures formation. We present the surface morphologies obtained by this model for different polarizations of the incident laser electric field and show good agreement with ripple formation produced by laser ablation experiments. The correlation of ripples orientation with laser polarization can be described within a model where the polarization causes a breaking of symmetry at the surface. Further we discuss a time evolution of pattern formation. Our results support the non-linear self-organization mechanism of pattern formation on the surface of solids.     

Detection and implications of a time-reversal breaking state in underdoped cuprates

We present general symmetry considerations on how a time-reversal breaking state may be detected by angle-resolved photoemission using circularly polarized photons as has been proposed earlier. Results of recent experiments utilizing the proposal in underdoped cuprates are analyzed and found to be consistent in their symmetry and magnitude with a theory of the copper oxides. These experiments if correct, together with evidence of a quantum critical point and marginal Fermi-liquid properties near optimum doping, suggest that the essentials of a valid microscopic theory of the phenomena in the cuprates may have been found.     

Experimental observation of optical bound states in the continuum

We present the experimental observation of bound states in the continuum. Our experiments are carried out in an optical waveguide array structure, where the bound state (guided mode) is decoupled from the continuum by virtue of symmetry only. We demonstrate that breaking the symmetry of the system couples this special bound state to continuum states, leading to radiative losses. These experiments demonstrate ideas initially proposed by von Neumann and Wigner in 1929 and offer new possibilities for integrated optical elements and analogous realizations with cold atoms and optical trapping of particles.     

Relating mHiggs to mSUSY by a loop factor

We assume that the scale of the soft supersymmetry breaking masses, m_S, sliding at tree level, is fixed by the minimization of the potential, but without a significant contribution of the cosmological term. Under these assumptions the electroweak breaking scale gets related to m_S by a loop factor. Applied to specific models of supersymmetry breaking, this mechanism naturally gives sparticles slightly above all present accelerator bounds.     

Third generation Yukawa couplings unification in supersymmetric SO(10) model

In the minimal supersymmetric standard model (MSSM) contained in SUSY SO(10), top-- Yukawa unification is achieved at the intermediate mass scale GeV using the recent world average experimental value of the top-quark mass, GeV, which has been directly established by CDF and D0 experiments at the Tevatron Collider. It is also observed that the Yukawa couplings unification scale can be further decreased by taking lower input values of the top-quark mass. This trend indicates the possible existence of an intermediate symmetry breaking scale in SUSY SO(10). The present finding does not agree with the earlier notion that the third generation Yukawa couplings unification should occur at the GUT scale . Received: 22 September 1997 / Revised version: 22 January 1998 / Published online: 24 March 1998     

Employing Higgs boson production at photon colliders to discriminate between the two Higgs doublet model and the standard model in the process <Emphasis Type="Italic">eγ</Emphasis> → <Emphasis Type="Italic">eh</Emphasis>

The possibility of employing experiments at photon colliders to discriminate between various models of electroweak-symmetry breaking is discussed for the case where experiments at LHC and at future linear electron-positron colliders reveal no disagreement with the predictions of the Standard Model (SM)—that is, the case of an SM-like scenario. The two Higgs boson doublet model (2HDM) is considered as an alternative to the SM. A comparison of the cross sections obtained for the process eγ → eh within the SM and the natural 2HDM shows that investigation of this cross section would make it possible to discriminate between these models of electroweak-symmetry breaking reliably and to confirm or disprove the results obtained by studying the reaction γγ → h.     

Breaking of longitudinal Akhiezer-Polovin waves

The breaking of longitudinal Akhiezer-Polovin (AP) waves is demonstrated using a one-dimensional simulation based on the Dawson sheet model. It is found that the AP longitudinal waves break through the process of phase mixing at an amplitude well below the breaking amplitude for AP waves, when subjected to arbitrarily small longitudinal perturbations. Results from the simulation show a good agreement with the Dawson phase mixing formula modified to include relativistic mass variation effects. This result may be of direct relevance to the laser- or particle-beam plasma wakefield experiments.     

Perturbative vs. non-perturbative scaling violation in quark fragmentation

We investigate the approach to scaling for non-perturbative quark fragmentation in the frame-work of the uncorrelated jet model. It is found that subasymptotic kinematic scale breaking is comparable in size to scaling violations from hard gluon emission a la QCD. Experimental data available at present do allow for such non-perturbative scale breaking effects.     

包含轻子结构的夸克模型

对标准模型作手征性扩充后,模型中平行地存在手征性相反的夸克态.相应于构成强子的f代普通夸克,新加的同样代数、手征性相反的夸克可能构成轻子.对扩充后的模型超对称化之后,使得渐近自由性质的破坏所要求的代的数目从大于33/8减少到大于9/4,从而有可能解释手征相反的夸克构成的轻子为什么比普通夸克构成的强子大小要小得多等特点.     

Neutralino phenomenology at LEP2 in supersymmetry with bilinear breaking of R-parity

We discuss the phenomenology of the lightest neutralino in models where an effective bilinear term in the superpotential parametrizes the explicit breaking of R-parity. We consider supergravity scenarios where the lightest supersymmetric particle (LSP) is the lightest neutralino and which can be explored at LEP2. We present a detailed study of the LSP decay properties and general features of the corresponding signals expected at LEP2. We also contrast our model with gauge mediated supersymmetry breaking.     

On the sgoldstino interpretation of the diphoton excess

We point out that the diphoton excess at about 750 GeV recently discovered by the LHC experiments can be explained within supersymmetric models with low scale supersymmetry breaking with sgoldstino as a natural candidate. We discuss phenomenological consequences of this scenario describing possible signatures to test this hypothesis.     

荧光标记微管的光敏断裂及机理

荧光标记的微管经激发光照射会引起微管的断裂，但其断裂过程及机理并不清楚.通过光镊研究了微管光敏断裂的动态过程.实验结果表明组成微管的原丝并不是同时断裂的，而是相继断裂最终导致微管的断裂.经过一系列生物学实验，确定了活性氧中的自由基是造成微管光敏断裂的主要因素.根据光镊研究的结果推测了自由基作用于微管的机理. 关键词： 光镊 微管 断裂 自由基