The chiral magnetic effect is the generation of electric current induced by chirality imbalance in the presence of magnetic field. It is a macroscopic manifestation of the quantum anomaly in relativistic field theory of chiral fermions (massless spin
$1/2$ particles with a definite projection of spin on momentum) -- a dramatic phenomenon arising from a collective motion of particles and antiparticles in the Dirac sea. The recent discovery of Dirac semimetals with chiral quasi-particles opens a fascinating possibility to study this phenomenon in condensed matter experiments. Here we report on the first observation of chiral magnetic effect through the measurement of magneto-transport in zirconium pentatelluride, ZrTe_5. Our angle-resolved photoemission spectroscopy experiments show that this materials electronic structure is consistent with a 3D Dirac semimetal. We observe a large negative magnetoresistance when magnetic field is parallel with the current. The measured quadratic field dependence of the magnetoconductance is a clear indication of the chiral magnetic effect. The observed phenomenon stems from the effective transmutation of Dirac semimetal into a Weyl semimetal induced by the parallel electric and magnetic fields that represent a topologically nontrivial gauge field background.
Triple gauge boson associated production at the LHC serves as an interesting channel to test the robustness of the Standard Model. Any deviation from its SM prediction may indicate possible existence of relevant new physics, e.g., anomalous quartic g
auge boson couplings. In this paper, a Monte-Carlo feasibility study of measuring WWA production with pure leptonic decays and probing anomalous quartic gauge-boson (e.g., WWAA) couplings, is presented in detail for the first time, with parton shower and detector simulation effects taken into account. Our results show that at the sqrt{s} = 14 TeV LHC with an integrated luminosity of 100 (30) fb-1, one can reach a significance of 9 (5) sigma to observe the SM WWA production, and can constrain at the 95% CL the anomalous WWAA coupling parameters, e.g., a_{0,c}^W/Lambda^2 (see Ref.[15] for their definitions), at 10^{-5} GeV^{-2}, respectively.
We present an experimental study of the anisotropic resistivity of superconducting La(2-x)Ba(x)CuO(4) with x=0.095 and transition temperature Tc=32 K. In a magnetic field perpendicular to the CuO(2) layers, H(perp), we observe that the resistivity pe
rpendicular to the layers, rho(perp), becomes finite at a temperature consistent with previous studies on very similar materials; however, the onset of finite parallel resistivity, rho(par), occurs at a much higher temperature. This behavior contradicts conventional theory, which predicts that rho(perp) and rho(par) should become finite at the same temperature. Voltage vs. current measurements near the threshold of voltage detectability indicate linear behavior perpendicular to the layers, becoming nonlinear at higher currents, while the behavior is nonlinear from the onset parallel to the layers. These results, in the presence of moderate H(perp), appear consistent with superconducting order parallel to the layers with voltage fluctuations between the layers due to thermal noise. In search of uncommon effects that might help to explain this behavior, we have performed diffraction measurements that provide evidence for H(perp)-induced charge and spin stripe order. The field-induced decoupling of superconducting layers is similar to the decoupled phase observed previously in La(2-x)Ba(x)CuO(4) with x=1/8 in zero field.
Enormous successes have been made by quantum algorithms during the last decade. In this paper, we combine the quantum game with the problem of data clustering, and then develop a quantum-game-based clustering algorithm, in which data points in a data
set are considered as players who can make decisions and implement quantum strategies in quantum games. After each round of a quantum game, each players expected payoff is calculated. Later, he uses a link-removing-and-rewiring (LRR) function to change his neighbors and adjust the strength of links connecting to them in order to maximize his payoff. Further, algorithms are discussed and analyzed in two cases of strategies, two payoff matrixes and two LRR functions. Consequently, the simulation results have demonstrated that data points in datasets are clustered reasonably and efficiently, and the clustering algorithms have fast rates of convergence. Moreover, the comparison with other algorithms also provides an indication of the effectiveness of the proposed approach.
We present an analysis of non-leptonic B decays in the minimally flavour-violating MSSM with large tan(beta). We relate the Wilson coefficients of the relevant hadronic scalar operators to leptonic observables, showing that the present limits on the
Bs->mu+ mu- and B+->tau nu_tau branching fractions exclude any visible effect in hadronic decays. We study the transverse helicity amplitudes of B->VV decays, which exhibit an enhanced sensitivity to the scalar operators, showing that even though an order one modification relative to the SM is not excluded in some of these amplitudes, they are too small to be detected at B factories.
The enormous successes have been made by quantum algorithms during the last decade. In this paper, we combine the quantum random walk (QRW) with the problem of data clustering, and develop two clustering algorithms based on the one dimensional QRW. T
hen, the probability distributions on the positions induced by QRW in these algorithms are investigated, which also indicates the possibility of obtaining better results. Consequently, the experimental results have demonstrated that data points in datasets are clustered reasonably and efficiently, and the clustering algorithms are of fast rates of convergence. Moreover, the comparison with other algorithms also provides an indication of the effectiveness of the proposed approach.
We introduce a modified model of random walk, and then develop two novel clustering algorithms based on it. In the algorithms, each data point in a dataset is considered as a particle which can move at random in space according to the preset rules in
the modified model. Further, this data point may be also viewed as a local control subsystem, in which the controller adjusts its transition probability vector in terms of the feedbacks of all data points, and then its transition direction is identified by an event-generating function. Finally, the positions of all data points are updated. As they move in space, data points collect gradually and some separating parts emerge among them automatically. As a consequence, data points that belong to the same class are located at a same position, whereas those that belong to different classes are away from one another. Moreover, the experimental results have demonstrated that data points in the test datasets are clustered reasonably and efficiently, and the comparison with other algorithms also provides an indication of the effectiveness of the proposed algorithms.
Fortran subroutines to calculate helicity amplitudes with massive spin-2 particles (massive gravitons), which couple to the standard model particles via the energy momentum tensor, are added to the {tt HELAS} ({tt HEL}icity {tt A}mplitude {tt S}ubrou
tines) library. They are coded in such a way that arbitrary scattering amplitudes with one graviton production and its decays can be generated automatically by {tt MadGraph} and {tt MadEvent}, after slight modifications. All the codes have been tested carefully by making use of the invariance of the helicity amplitudes under the gauge and general coordinate transformations.
We study Kaluza-Klein (KK) graviton production in the large extra dimensions model via 2 jets plus missing transverse momentum signatures at the LHC. We make predictions for both the signal and the dominant Zjj and Wjj backgrounds, where we introduce
missing P_T-dependent jet selection cuts that ensure the smallness of the 2-jet rate over the 1-jet rate. With the same jet selection cuts, the distributions of the two jets and their correlation with the missing transverse momentum provide additional evidence for the production of an invisible massive object.
The Modified Horizontal Bridgman (MHB) process produces Cadmium Zinc Telluride (CZT) crystals with high yield and excellent homogeneity. Various groups,including our own, previously reported on the test of 2x2x0.5 cm3 MHB CZT detectors grown by the c
ompany Orbotech and read out with 8x8 pixels. In this contribution, we describe the optimization of the photolithographic process used for contacting the CZT detector with pixel contacts. The optimized process gives a high yield of good pixels down to pixel diameters/pitches of 50 microns. Furthermore, we discuss the performance of 0.5 cm and 0.75 cm thick detectors contacted with 64 and 225 pixel read out with the RENA-3 ASICs from the company NOVA R&D.
