Dynamical Chern-Simons gravity cannot be strongly constrained with current experiments because it reduces to general relativity in the weak-field limit. This theory, however, introduces modifications in the nonlinear, dynamical regime, and thus it could be greatly constrained with gravitational waves from the late inspiral of black-hole binaries. We complete the first self-consistent calculation of such gravitational waves in this theory. For favorable spin orientations, advanced ground-based detectors may improve existing solar system constraints by 6 orders of magnitude.

We report an investigation of the invariant mass spectrum of the two jets with highest transverse momentum in $pp\to W+2$-jet and $W+3$-jet events to look for resonant enhancement. The data sample corresponds to an integrated luminosity of $5.0{\mathrm{fb}}^{-1}$ collected with the CMS detector at $\sqrt{s}=7\mathrm{TeV}$. We find no evidence for the anomalous structure reported by the CDF Collaboration, and establish an upper limit of 5.0 pb at 95% confidence level on the production cross section for a generic Gaussian signal with mass near 150 GeV. Additionally, we exclude two theoretical models that predict a CDF-like dijet resonance near 150 GeV.

According to the path-integral formalism of the hadronic tensor, the nucleon sea contains two distinct components called the connected sea (CS) and the disconnected sea (DS). We discuss how the CS and DS are accessed in the lattice QCD calculation of the moments of the parton distributions. We show that the CS and DS components of $\overline{u}(x)+\overline{d}(x)$ can be extracted by using recent data on the strangeness parton distribution, the CT10 global fit, and the lattice result of the ratio of the strange to $u(d)$ moments in the disconnected insertion. The extracted CS and DS for $\overline{u}(x)+\overline{d}(x)$ have a distinct Bjorken $x$ dependence in qualitative agreement with expectation. The analysis also shows that the momentum fraction of $\overline{u}(x)+\overline{d}(x)$ is about equally divided between the CS and DS at $Q^2=2.5{\mathrm{GeV}}^2$. Implications for the future global analysis of parton distributions are presented.

The configuration interaction (CI) is a versatile wave function theory for interacting fermions, but it involves an extremely long CI series. Using a symmetric tensor decomposition method, we convert the CI series into a compact and numerically tractable form. The converted series encompasses the Hartree-Fock state in the first term and rapidly converges to the full-CI state, as numerically tested by using small molecules. Provided that the length of the symmetric tensor decomposition CI series grows only moderately with the increasing complexity of the system, the new method will serve as one of the alternative variational methods to achieve full CI with enhanced practicability.

We examine the impact of a perpendicular magnetic field on the creation mechanism of electron-positron pairs in a supercritical static electric field, where both fields are localized along the direction of the electric field. In the case where the spatial extent of the magnetic field exceeds that of the electric field, quantum field theoretical simulations based on the Dirac equation predict a suppression of pair creation even if the electric field is supercritical. Furthermore, an arbitrarily small magnetic field outside the interaction zone can bring the creation process even to a complete halt, if it is sufficiently extended. The mechanism for this magnetically induced complete shutoff can be associated with a reopening of the mass gap and the emergence of electrically dressed Landau levels.

The search for Majorana fermions in $p$-wave paired fermionic systems has recently moved to the forefront of condensed matter research. Here we propose an alternative route and show theoretically that Majorana-like modes can be realized and probed in a driven-dissipative system of strongly correlated photons consisting of a chain of tunnel-coupled cavities, where $p$-wave pairing effectively arises from the interplay between strong on-site interactions and two-photon parametric driving. The nonlocal nature of these exotic modes could be demonstrated through cross-correlation measurements carried out at the ends of the chain—revealing a strong photon-bunching signature—and their non-Abelian properties could be simulated through tunnel-braid operations.

We demonstrate, via simulations of asymptotically reduced equations describing rotationally constrained Rayleigh-Bénard convection, that the efficiency of turbulent motion in the fluid bulk limits overall heat transport and determines the scaling of the nondimensional Nusselt number $\mathrm{Nu}$ with the Rayleigh number $\mathrm{Ra}$, the Ekman number $E$, and the Prandtl number $\sigma$. For $E\ll 1$ inviscid scaling theory predicts and simulations confirm the large $\mathrm{Ra}$ scaling law $\mathrm{Nu}-1\approx C_1{\sigma }^{-1/2}\mathrm{R}{\mathrm{a}}^{3/2}{E}^2$, where $C_1$ is a constant, estimated as $C_1\approx 0.04\pm 0.0025$. In contrast, the corresponding result for nonrotating convection, $\mathrm{Nu}-1\approx C_2\mathrm{R}{\mathrm{a}}^{\alpha }$, is determined by the efficiency of the thermal boundary layers (laminar: $0.28\lesssim \alpha \lesssim 0.31$, turbulent: $\alpha \sim 0.38$). The $3/2$ scaling law breaks down at Rayleigh numbers at which the thermal boundary layer loses rotational constraint, i.e., when the local Rossby number $\approx 1$. The breakdown takes place while the bulk Rossby number is still small and results in a gradual transition to the nonrotating scaling law. For low Ekman numbers the location of this transition is independent of the mechanical boundary conditions.

Non-neutral plasmas can be trapped for long times by means of combined electric and magnetic fields. Adiabatic cooling is achieved by slowly decreasing the trapping frequency and letting the plasma occupy a larger volume. We develop a fully kinetic time-dependent theory of adiabatic cooling for plasmas trapped in a one-dimensional well. This approach is further extended to three dimensions and applied to the cooling of antiproton plasmas, showing excellent agreement with recent experiments [Gabrielse et al., Phys. Rev. Lett. 106, 073002 (2011)].

The fundamental instability responsible for the shear localization which results in shear bands in amorphous solids remains unknown despite an enormous amount of research, both experimental and theoretical. As this is the main mechanism for the failure of metallic glasses, understanding the instability is invaluable in finding how to stabilize such materials against the tendency to shear localize. In this Letter we explain the mechanism for shear localization under shear, which is the appearance of highly correlated lines of Eshelby-like quadrupolar singularities which organize the nonaffine plastic flow of the amorphous solid into a shear band. We prove analytically that such highly correlated solutions in which $\mathcal{N}$ quadrupoles are aligned with equal orientations are minimum energy states when the strain is high enough. The line lies at 45 degrees to the compressive stress.

We investigate the role of disorder on the fracturing process of heterogeneous materials by means of a two-dimensional fuse network model. Our results in the extreme disorder limit reveal that the backbone of the fracture at collapse, namely, the subset of the largest fracture that effectively halts the global current, has a fractal dimension of $1.22\pm 0.01$. This exponent value is compatible with the universality class of several other physical models, including optimal paths under strong disorder, disordered polymers, watersheds and optimal path cracks on uncorrelated substrates, hulls of explosive percolation clusters, and strands of invasion percolation fronts. Moreover, we find that the fractal dimension of the largest fracture under extreme disorder, $d_f=1.86\pm 0.01$, is outside the statistical error bar of standard percolation. This discrepancy is due to the appearance of trapped regions or cavities of all sizes that remain intact till the entire collapse of the fuse network, but are always accessible in the case of standard percolation. Finally, we quantify the role of disorder on the structure of the largest cluster, as well as on the backbone of the fracture, in terms of a distinctive transition from weak to strong disorder characterized by a new crossover exponent.

We study the spectrum of a one-dimensional Kitaev chain placed in a microwave cavity. In the off-resonant regime, the frequency shift of the cavity can be used to identify the topological phase transition of the coupled system. In the resonant regime, the topology of the system is sensitive to the presence of photons in the microwave cavity and, moreover, for a large number of photons (classical limit), the physics becomes similar to that of periodically driven systems (Floquet insulators). We also analyze numerically a finite chain and show the existence of a degenerate subspace in the presence of the cavity that can be interpreted as a Majorana polariton.

We report the magnetic and electric properties of ${\mathrm{Ba}}_3{\mathrm{NiNb}}_2{\mathrm{O}}_9$, which is a quasi-two-dimensional spin-one triangular-lattice antiferromagnet with trigonal structure. At low $T$ and with increasing magnetic field, the system evolves from a 120 degree magnetic ordering phase ($A$ phase) to an up-up-down ($uud$) phase ($B$ phase) with a change of slope at $1/3$ of the saturation magnetization, and then to an “oblique” phase ($C$ phase). Accordingly, the ferroelectricity switches on at each phase boundary with appearance of spontaneous polarization. Therefore, ${\mathrm{Ba}}_3{\mathrm{NiNb}}_2{\mathrm{O}}_9$ is a unique triangular-lattice antiferromagnet exhibiting both $uud$ phase and multiferroicity.

We describe a novel type of ordering phenomenon associated with the incommensurate occupational modulation of bistable molecular magnetic state in a spin-crossover material. This unusual type of aperiodicity resulting from the ordering of multistable electronic states opens new possibilities for addressing such materials by light. Here we show that light can switch the crystal from four- to three-dimensional periodic structure. Mixing aperiodicity, multistability, and photoinduced phenomenà opens new perspectives for directing complex order and function in material science.

We demonstrate the plasmonic analogue of a coherent photonic effect known as coherent perfect absorption. A periodically nanopatterned metal film perfectly absorbs multiple coherent light beams coupling to a single surface plasmon mode. The perfect absorbing state can be switched to a nearly perfect scattering state by tuning the phase difference between the incident beams. We theoretically explain the plasmonic coherent perfect absorption by considering time-reversal symmetry of surface plasmon amplification by stimulated emission of radiation. We experimentally demonstrate coherent control of the plasmonic absorption in good agreement with a coupled-mode theory of dissipative resonances. Associated potential applications include absorption-based plasmonic switches, modulators, and light-electricity transducers.

We have investigated the contribution of 90° domain walls and thermal expansion mismatch to pyroelectricity in ${\mathrm{PbZr}}_{0.2}{\mathrm{Ti}}_{0.8}{\mathrm{O}}_3$ thin films. The first phenomenological models to include extrinsic and secondary contributions to pyroelectricity in polydomain films predict significant extrinsic contributions (arising from the temperature-dependent motion of domain walls) and large secondary contributions (arising from thermal expansion mismatch between the film and the substrate). Phase-sensitive pyroelectric current measurements are applied to model thin films for the first time and reveal a dramatic increase in the pyroelectric coefficient with increasing fraction of in-plane oriented domains and thermal expansion mismatch.

I present lattice Monte Carlo calculations for a universal four-component Fermi gas confined to a finite box and to a harmonic trap in one spatial dimension. I obtain the values ${\xi }_{1D}=0.370(4)$ and ${\xi }_{1D}=0.372(1)$, respectively, for the Bertsch parameter, a nonperturbative universal constant defined as the (square of the) energy of the untrapped (trapped) system measured in units of the free gas energy. The Bertsch parameter obtained for the one-dimensional system is consistent to within $\sim 1\%$ uncertainties with the most recent numerical and experimental estimates of the analogous Bertsch parameter for a three-dimensional spin-$1/2$ Fermi gas at unitarity. The finding suggests the intriguing possibility that there exists a universality between two conformal theories in different dimensions. To lend support to this study, I also compute ground state energies for four and five fermions confined to a harmonic trap and demonstrate the restoration of a virial theorem in the continuum limit. The continuum few-body energies obtained are consistent with exact analytical calculations to within $\sim 1.0\%$ and $\sim 0.3\%$ statistical uncertainties, respectively.

A quantum-dot hybrid qubit formed from three electrons in a double quantum dot has the potential for great speed, due to the presence of level crossings where the qubit becomes chargelike. Here, we show how to exploit the level crossings to implement fast pulsed gating. We develop one- and two-qubit dc quantum gates that are simpler than the previously proposed ac gates. We obtain closed-form solutions for the control sequences and show that the gates are fast (subnanosecond) and can achieve high fidelities.

We perform three-flavor Boltzmann neutrino transport radiation hydrodynamics simulations covering a period of 3 s after the formation of a protoneutron star in a core-collapse supernova explosion. Our results show that a treatment of charged-current neutrino interactions in hot and dense matter as suggested by Reddy et al. [Phys. Rev. D 58, 013009 (1998)] has a strong impact on the luminosities and spectra of the emitted neutrinos. When compared with simulations that neglect mean-field effects on the neutrino opacities, we find that the luminosities of all neutrino flavors are reduced while the spectral differences between electron neutrinos and antineutrinos are increased. Their magnitude depends on the equation of state and in particular on the symmetry energy at subnuclear densities. These modifications reduce the proton-to-nucleon ratio of the outflow, increasing slightly their entropy. They are expected to have a substantial impact on nucleosynthesis in neutrino-driven winds, even though they do not result in conditions that favor an $r$ process. Contrary to previous findings, our results show that the spectra of electron neutrinos remain substantially different from those of other (anti)neutrino flavors during the entire deleptonization phase of the protoneutron star. The obtained luminosity and spectral changes are also expected to have important consequences for neutrino flavor oscillations and neutrino detection on Earth.

If the neutral component of weak-scale dark matter is accompanied by a charged excitation separated by a mass gap of less than $\sim 20\mathrm{MeV}$, weakly interacting massive particles (WIMPs) can form stable bound states with nuclei. We show that the recent progress in experiments searching for neutrinoless double-beta decay sets the first direct constraint on the exoergic reaction of WIMP-nucleus bound state formation. We calculate the rate for such a process in representative models and show that the double-beta decay experiments provide unique sensitivity to a large fraction of parameter space of the WIMP doublet model, complementary to constraints imposed by cosmology and direct collider searches.

We show that extreme vacuum pressures can be measured with current technology by detecting the photons produced by the relativistic Thomson scattering of ultraintense laser light by the electrons of the medium. We compute the amount of radiation scattered at different frequencies and angles when a Gaussian laser pulse crosses a vacuum tube and design strategies for the efficient measurement of pressure. In particular, we show that a single day experiment at a high repetition rate petawatt laser facility such as Vega, that will be operating in 2014 in Salamanca, will be sensitive, in principle, to pressures $p$ as low as ${10}^{-16}\mathrm{Pa}$, and will be able to provide highly reliable measurements for $p\gtrsim {10}^{-14}\mathrm{Pa}$.