10,843 research outputs found

    Chiral Perturbation Theory and U(3)_L\times U(3)_R Chiral Theory of Mesons

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    We examine low energy limit of U(3)L×U(3)RU(3)_L\times U(3)_R chiral theory of mesons through integrating out fields of vector and axial-vector mesons. The effective lagrangian for pseudoscalar mesons at O(p4)O(p^4) has been obtained, and five low energy coupling constants Li(i=1,2,3,9,10)L_i(i=1,2,3,9,10) have been revealed. They are in good agreement with the results of CHPT's at Ό∌mρ\mu \sim m_\rho.Comment: 20 pages, Standard LaTex file, no finger

    Experimental Realization of Br\"{u}schweiler's exponentially fast search algorithm in a homo-nuclear system

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    Compared with classical search algorithms, Grover quantum algorithm [ Phys. Rev. Lett., 79, 325(1997)] achieves quadratic speedup and Bruschweiler hybrid quantum algorithm [Phys. Rev. Lett., 85, 4815(2000)] achieves an exponential speedup. In this paper, we report the experimental realization of the Bruschweiler$ algorithm in a 3-qubit NMR ensemble system. The pulse sequences are used for the algorithms and the measurement method used here is improved on that used by Bruschweiler, namely, instead of quantitatively measuring the spin projection of the ancilla bit, we utilize the shape of the ancilla bit spectrum. By simply judging the downwardness or upwardness of the corresponding peaks in an ancilla bit spectrum, the bit value of the marked state can be read out, especially, the geometric nature of this read-out can make the results more robust against errors.Comment: 10 pages and 3 figure

    Nanoplasmonics beyond Ohm's law

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    In tiny metallic nanostructures, quantum confinement and nonlocal response change the collective plasmonic behavior with important consequences for e.g. field-enhancement and extinction cross sections. We report on our most recent developments of a real-space formulation of an equation-of-motion that goes beyond the common local-response approximation and use of Ohm's law as the central constitutive equation. The electron gas is treated within a semi-classical hydrodynamic model with the emergence of a new intrinsic length scale. We briefly review the new governing wave equations and give examples of applying the nonlocal framework to calculation of extinction cross sections and field enhancement in isolated particles, dimers, and corrugated surfaces.Comment: Invited paper for TaCoNa-Photonics 2012 (www.tacona-photonics.org), to appear in AIP Conf. Pro

    New spectrum of negative-parity doubly charmed baryons: Possibility of two quasistable states

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    The discovery of Ξcc++\Xi_{cc}^{++} by the LHCb Collaboration triggers predictions of more doubly charmed baryons. By taking into account both the PP-wave excitations between the two charm quarks and the scattering of light pseudoscalar mesons off the ground state doubly charmed baryons, a set of negative-parity spin-1/2 doubly charmed baryons are predicted already from a unitarized version of leading order chiral perturbation theory. Moreover, employing heavy antiquark-diquark symmetry the relevant low-energy constants in the next-to-leading order are connected with those describing light pseudoscalar mesons scattering off charmed mesons, which have been well determined from lattice calculations and experimental data. Our calculations result in a spectrum richer than that of heavy mesons. We find two very narrow JP=1/2−J^P=1/2^- ΩccP\Omega_{cc}^P, which very likely decay into Ωccπ0\Omega_{cc}\pi^0 breaking isospin symmetry. In the isospin-1/2 ΞccP\Xi_{cc}^P sector, three states are predicted to exist below 4.2~GeV with the lowest one being narrow and the other two rather broad. We suggest to search for the ΞccP\Xi_{cc}^{P} states in the Ξcc++π−\Xi_{cc}^{++}\pi^- mode. Searching for them and their analogues are helpful to establish the hadron spectrum.Comment: 6 pages, 3 figures; accepted for publication as a Rapid Communication in Physical Review

    Variation of the Fine-Structure Constant from the de Sitter Invariant Special Relativity

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    There are obvious discrepancies among various experimental constraints on the variation of the fine-structure constant, α\alpha. We attempt to discuss the issue in the framework of de Sitter invariant Special Relativity (SRc,R{\cal SR}_{c,R}) and to present a possible solution to the disagreement. In addition, on the basis of the observational data and the discussions presented in this Letter, we derive a rough theoretical estimate of the radius of the Universe.Comment: 8 pages, no figure

    Depleted Energy Charge and Increased Pulmonary Endothelial Permeability Induced by Mitochondrial Complex I inhibition are Mitigated by Coenzyme Q\u3csub\u3e1\u3c/sub\u3e in the Isolated Perfused Rat Lung

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    Mitochondrial dysfunction is associated with various forms of lung injury and disease that also involve alterations in pulmonary endothelial permeability, but the relationship, if any, between the two is not well understood. This question was addressed by perfusing isolated intact rat lung with a buffered physiological saline solution in the absence or presence of the mitochondrial complex I inhibitor rotenone (20 ÎŒM). Compared to control, rotenone depressed whole lung tissue ATP from 5.66±0.46 (SEM) to 2.34±0.15 ”mol·g−1 dry lung, with concomitant increases in the ADP:ATP and AMP:ATP ratios. Rotenone also increased lung perfusate lactate (from 12.36±1.64 to 38.62±3.14 ”mol·15 min−1 perfusion·g−1 dry lung) and the lactate:pyruvate ratio, but had no detectable impact on lung tissue GSH:GSSG redox status. The amphipathic quinone coenzyme Q1 (CoQ1; 50 ÎŒM) mitigated the impact of rotenone on the adenine nucleotide balance, wherein mitigation was blocked by NAD(P)H-quinone oxidoreductase 1 or mitochondrial complex III inhibitors. In separate studies, rotenone increased the pulmonary vascular endothelial filtration coefficient (Kf) from 0.043±0.010 to 0.156±0.037 ml·min−1·cm H2O−1·g−1 dry lung, and CoQ1 protected against the effect of rotenone on Kf. A second complex I inhibitor, piericidin A, qualitatively reproduced the impact of rotenone on Kf and the lactate:pyruvate ratio. Taken together, the observations imply that pulmonary endothelial barrier integrity depends on mitochondrial bioenergetics as reflected in lung tissue ATP levels and that compensatory activation of whole lung glycolysis cannot protect against pulmonary endothelial hyperpermeability in response to mitochondrial blockade. The study further suggests that low-molecular-weight amphipathic quinones may have therapeutic utility in protecting lung barrier function in mitochondrial insufficiency

    Influence of charge status on the stress safety properties of Li(Ni₁⁄₃Co₁⁄₃Mn₁⁄₃)O₂ cells

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    In order to improve safety management, the stress changes of Li(Ni1/3Co1/3Mn1/3)O2 (NMC) cells are real-time monitored using non-destructive strain gauges, and the effects of gauge substrate, temperature and state-of-charge (SOC) have been investigated. The shell exhibits elastic deformation behaviour, and the strain-stress relationship is established. As the temperature increases from 25 to 80 °C, the stress of the NMC cells increases from 0 to 275 MPa, especially greatly at 70 °C and sharply at 80 °C after 18 h. The stress increases from 0 to 9.2 MPa when the potential increases from 2.8 to 4.3 V. However, the value rises from 10 to 55 MPa when the voltage increases from 4.6 to 5.0 V during the over-charge process. An obvious increase of stress appears when the cut-off voltage is below 0.6 V during over-discharge tests. The facile method is significant for non-destructive inspection and emergency management of batteries

    Electrical Control of Two-Dimensional Neutral and Charged Excitons in a Monolayer Semiconductor

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    Monolayer group VI transition metal dichalcogenides have recently emerged as semiconducting alternatives to graphene in which the true two-dimensionality (2D) is expected to illuminate new semiconducting physics. Here we investigate excitons and trions (their singly charged counterparts) which have thus far been challenging to generate and control in the ultimate 2D limit. Utilizing high quality monolayer molybdenum diselenide (MoSe2), we report the unambiguous observation and electrostatic tunability of charging effects in positively charged (X+), neutral (Xo), and negatively charged (X-) excitons in field effect transistors via photoluminescence. The trion charging energy is large (30 meV), enhanced by strong confinement and heavy effective masses, while the linewidth is narrow (5 meV) at temperatures below 55 K. This is greater spectral contrast than in any known quasi-2D system. We also find the charging energies for X+ and X- to be nearly identical implying the same effective mass for electrons and holes.Comment: 11 pages main text with 4 figures + 7 pages supplemental material
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