Angular analysis of B -> J/psi K1 : towards a model independent determination of the photon polarization with B-> K1 gamma

We propose a model independent extraction of the hadronic information needed to determine the photon polarization of the b-> s gamma process by the method utilizing the B -> K1 gamma -> K pi pi gamma angular distribution. We show that exactly the same hadronic information can be obtained by using the B -> J/psi K1 -> J/psi K pi pi channel, which leads to a much higher precision.Comment: 12 pages, 1 figur

Spin-charge Separation in Nodal Antiferromagnetic Insulator

In this paper, by using two dimensional (2D) Hubbard models with pi-flux phase and that on a hexagonal lattice as examples, we explore spin-charge-separated solitons in nodal antiferromagnetic (AF) insulator - an AF order with massive Dirac fermionic excitations (see detail in the paper). We calculate fermion zero modes and induced quantum numbers on solitons (half skyrmions) in the continuum limit, which are similar to that in the quasi one-dimensional conductor polyacetylene (CH)x and that in topological band insulator. In particular, we find some novel phenomena : thanks to an induced staggered spin moment, a mobile half skyrmion becomes a fermionic particle; when a hole or an electron is added, the half skyrmion turns into a bosonic particle with charge degree of freedom only. Our results imply that nontrivial induced quantum number on solitons may be a universal feature of spin-charge separation in different systems

CP asymmetry and branching ratio of B -> pi pi

We investigate the branching ratios and CP asymmetries of the B -> pi pi processes measured in B factory experiments. Fits to the experimental data of this process indicate a large ratio of color-suppressed (C) to color-allowed (T) tree contributions. We investigate whether the large C/T can be explained within the QCD based model computation with i) a large effect from the end-point singularity or with ii) large final-state-interaction phase between two different isospin amplitudes. We show that the current experimental data do not exclude either possibility but we may be able to distinguish these two effects in future measurements of direct CP asymmetry of B -> pi^0 pi^0.Comment: 8 pages, 10 figure

Anomalous enhancement of a penguin hadronic matrix element in B->K eta'

We estimate the density matrix element for the pi^0, eta and eta' production from the vacuum in the large-N_c limit. As a consequence, we find that the QCD axial anomaly leads to highly non-trivial corrections to the usual flavour SU(3) relations between B^0-> K^0 pi^0, B^0-> K^0 eta and B^0-> K^0 eta' decay amplitudes. These corrections may explain why the B-> K eta' branching ratio is about six times larger than the B-> K pi one.Comment: 5 pages, 1 figur

Coulomb Oscillations in Antidots in the Integer and Fractional Quantum Hall Regimes

We report measurements of resistance oscillations in micron-scale antidots in both the integer and fractional quantum Hall regimes. In the integer regime, we conclude that oscillations are of the Coulomb type from the scaling of magnetic field period with the number of edges bound to the antidot. Based on both gate-voltage and field periods, we find at filling factor {\nu} = 2 a tunneling charge of e and two charged edges. Generalizing this picture to the fractional regime, we find (again, based on field and gate-voltage periods) at {\nu} = 2/3 a tunneling charge of (2/3)e and a single charged edge.Comment: related papers at http://marcuslab.harvard.ed

Influence of chemical and magnetic interface properties of Co-Fe-B / MgO / Co-Fe-B tunnel junctions on the annealing temperature dependence of the magnetoresistance

The knowledge of chemical and magnetic conditions at the Co40Fe40B20 / MgO interface is important to interpret the strong annealing temperature dependence of tunnel magnetoresistance of Co-Fe-B / MgO / Co-Fe-B magnetic tunnel junctions, which increases with annealing temperature from 20% after annealing at 200C up to a maximum value of 112% after annealing at 350C. While the well defined nearest neighbor ordering indicating crystallinity of the MgO barrier does not change by the annealing, a small amount of interfacial Fe-O at the lower Co-Fe-B / MgO interface is found in the as grown samples, which is completely reduced after annealing at 275C. This is accompanied by a simultaneous increase of the Fe magnetic moment and the tunnel magnetoresistance. However, the TMR of the MgO based junctions increases further for higher annealing temperature which can not be caused by Fe-O reduction. The occurrence of an x-ray absorption near-edge structure above the Fe and Co L-edges after annealing at 350C indicates the recrystallization of the Co-Fe-B electrode. This is prerequisite for coherent tunneling and has been suggested to be responsible for the further increase of the TMR above 275C. Simultaneously, the B concentration in the Co-Fe-B decreases with increasing annealing temperature, at least some of the B diffuses towards or into the MgO barrier and forms a B2O3 oxide

The effect of background music and noise on the cognitive test performance of Chinese introverts and extraverts

Previous research has shown that background auditory distractors (music and sound/noise) have a more severe impact on introverts’ performances on complex cognitive tasks than extraverts (Dobbs, Furnham, & McClelland, 2011). The present study is a partial replication of Dobbs et al., but involving Chinese rather than English participants. Ninety-two Chinese participants (59 female) carried out three cognitive tasks with the presence of Chinese pop songs, background office noise, and silence. The results did not reveal any differences in performance as a function of the distraction condition, nor was there a difference in performance between extraverts and introverts. The failure to replicate is explained in terms of habituation to noisy environments among Chinese participants