We present the threshold ${\mathrm{N}}^3\mathrm{LO}$ perturbative QCD corrections to the rapidity distributions of dileptons in the Drell-Yan process and Higgs boson in gluon fusion. Sudakov resummation of QCD amplitudes, renormalization group invariance, and the mass factorization theorem provide useful guidelines to obtain them in an elegant manner. We use various state of the art three loop results that have been recently available to obtain these distributions. For the Higgs boson, we demonstrate numerically the importance of these corrections at the LHC.

Highly mobile crystal defects such as crowdions and prismatic dislocation loops exhibit an anomalous temperature independent mobility unexplained by phonon scattering analysis. Using a projection operator, without recourse to elasticity, we derive analytic expressions for the mobility of highly mobile defects and dislocations which may be efficiently evaluated in molecular dynamics simulation. The theory explains how a temperature-independent mobility arises because defect motion is not an eigenmode of the Hessian, an implicit assumption in all previous treatments.

We present an unambiguous identification of low-frequency terahertz vibrations in the archetypal imidazole-based metal-organic framework (MOF) materials: ZIF-4, ZIF-7, and ZIF-8, all of which adopt a zeolite-like nanoporous structure. Using inelastic neutron scattering and synchrotron radiation far-infrared absorption spectroscopy, in conjunction with density functional theory (DFT), we have pinpointed all major sources of vibrational modes. Ab initio DFT calculations revealed the complex nature of the collective THz modes, which enable us to establish detailed correlations with experiments. We discover that low-energy conformational dynamics offers multiple pathways to elucidate novel physical phenomena observed in MOFs. New evidence demonstrates that THz modes are intrinsically linked, not only to anomalous elasticity underpinning gate-opening and pore-breathing mechanisms, but also to shear-induced phase transitions and the onset of structural instability.

${\mathrm{SmFeO}}_3$ has attracted considerable attention very recently due to its reported multiferroic properties above room temperature. We have performed powder and single crystal neutron diffraction as well as complementary polarization dependent soft X-ray absorption spectroscopy measurements on floating-zone grown ${\mathrm{SmFeO}}_3$ single crystals in order to determine its magnetic structure. We found a $k=0$ $G$-type collinear antiferromagnetic structure that is not compatible with inverse Dzyaloshinskii-Moriya interaction driven ferroelectricity. While the structural data reveal a clear sign for magneto-elastic coupling at the Néel-temperature of $\sim 675\mathrm{K}$, the dielectric measurements remain silent as far as ferroelectricity is concerned.

We demonstrate the tracking of the spin dynamics of ensemble and individual magnetic ferritin proteins from cryogenic up to room temperature using the nitrogen-vacancy color center in diamond as a magnetic sensor. We employ different detection protocols to probe the influence of the ferritin nanomagnets on the longitudinal and transverse relaxation of the nitrogen-vacancy center, which enables magnetic sensing over a wide frequency range from Hz to GHz. The temperature dependence of the observed spectral features can be well understood by the thermally induced magnetization reversals of the ferritin and enables the determination of the anisotropy barrier of single ferritin molecules.

We argue that the current heterogeneous computing environment mimics a complex nonlinear system which needs to borrow the concept of time-scale separation and the delayed difference approach from statistical mechanics and nonlinear dynamics. We show that by replacing the usual difference equations approach by a delayed difference equations approach, the sequential fraction of many scientific computing algorithms can be substantially reduced. We also provide a comprehensive theoretical analysis to establish that the error and stability of our scheme is of the same order as existing schemes for a large, well-characterized class of problems.

We present magnetization, specific heat, and ${}^{27}\mathrm{Al}$ NMR investigations on ${\mathrm{YbFe}}_2{\mathrm{Al}}_{10}$ over a wide range in temperature and magnetic field. The magnetic susceptibility at low temperatures is strongly enhanced at weak magnetic fields, accompanied by a $\ln (T_0/T)$ divergence of the low-$T$ specific heat coefficient in zero field, which indicates a ground state of correlated electrons. From our hard-x-ray photoemission spectroscopy study, the Yb valence at 50 K is evaluated to be 2.38. The system displays valence fluctuating behavior in the low to intermediate temperature range, whereas above 400 K, ${\mathrm{Yb}}^{3+}$ carries a full and stable moment, and Fe carries a moment of about $3.1{\mu }_B$. The enhanced value of the Sommerfeld-Wilson ratio and the dynamic scaling of the spin-lattice relaxation rate divided by $T[{}^{27}(1/T_{1}T)]$ with static susceptibility suggests admixed ferromagnetic correlations. ${}^{27}(1/T_{1}T)$ simultaneously tracks the valence fluctuations from the $4f$ Yb ions in the high temperature range and field dependent antiferromagnetic correlations among partially Kondo screened Fe $3d$ moments at low temperature; the latter evolve out of an Yb $4f$ admixed conduction band.

We introduce a model for thin films of multicomponent fluids that includes lateral and vertical phase separation, preferential component attraction at both surfaces, and surface roughening. We apply our model to thin films of binary polymer blends, and use simulations of different surface-blend interaction regimes to investigate pattern formation. We demonstrate that surface roughening couples to phase separation. For films undergoing lateral phase separation via a transient wetting layer, this results in distinct stages of roughening as the film evolves between different phase equilibria.

Charged gauge boson pair production at the Large Hadron Collider allows detailed probes of the fundamental structure of electroweak interactions. We present precise theoretical predictions for on-shell $W^{+}{W}^{-}$ production that include, for the first time, QCD effects up to next to next to leading order in perturbation theory. As compared to next to leading order, the inclusive $W^{+}{W}^{-}$ cross section is enhanced by 9% at 7 TeV and 12% at 14 TeV. The residual perturbative uncertainty is at the 3% level. The severe contamination of the $W^{+}{W}^{-}$ cross section due to top-quark resonances is discussed in detail. Comparing different definitions of top-free $W^{+}{W}^{-}$ production in the four and five flavor number schemes, we demonstrate that top-quark resonances can be separated from the inclusive $W^{+}{W}^{-}$ cross section without a significant loss of theoretical precision.

Using data collected with the BESIII detector operating at the Beijing Electron Positron Collider at center-of-mass energies of $\sqrt{s}=4.23$, 4.26, and 4.36 GeV, we observe $e^{+}{e}^{-}\to {\pi }^0{\pi }^0{h}_c$ for the first time. The Born cross sections are measured and found to be about half of those of $e^{+}{e}^{-}\to {\pi }^{+}{\pi }^{-}{h}_c$ within less than $2\sigma$. In the ${\pi }^0{h}_c$ mass spectrum, a structure at $4.02\mathrm{GeV}/c^2$ is found. It is most likely to be the neutral isospin partner of the $Z_c(4020{)}^{\pm }$ observed in the process of $e^{+}{e}^{-}\to {\pi }^{+}{\pi }^{-}{h}_c$ being found. A fit to the ${\pi }^0{h}_c$ invariant mass spectrum, with the width of the $Z_c(4020{)}^0$ fixed to that of its charged isospin partner and possible interferences with non-$Z_c(4020{)}^0$ amplitudes neglected, gives a mass of $(4023.9\pm 2.2\pm 3.8)\mathrm{MeV}/c^2$ for the $Z_c(4020{)}^0$, where the first error is statistical and the second systematic.

Motivated by recent experimental investigations of Cs-Cs-Li Efimov resonances, this work theoretically investigates the few-body properties of $N-1$ noninteracting identical heavy bosons, which interact with a light impurity through a large $s$-wave scattering length. For Cs-Cs-Cs-Li, we predict the existence of universal four-body states with energies $E_4^{(n,1)}$ and $E_4^{(n,2)}$, which are universally linked to the energy $E_3^{(n)}$ of the $n$th Efimov trimer. For infinitely large ${}^{133}\mathrm{Cs}\text{−}{}^6\mathrm{Li}$ and vanishing ${}^{133}\mathrm{Cs}\text{−}{}^{133}\mathrm{Cs}$ scattering lengths, we find $(E_4^{(1,1)}/E_3^{(1)}{)}^{1/2}\approx 1.51$ and $(E_4^{(1,2)}/E_3^{(1)}{)}^{1/2}\approx 1.01$. The ${}^{133}\mathrm{Cs}\text{−}{}^6\mathrm{Li}$ scattering lengths at which these states merge with the four-atom threshold, the dependence of these energy ratios on the mass ratio between the heavy and light atoms, and selected aspects of the generalized Efimov scenario for $N>4$ are also discussed. Possible implications of our results for ongoing cold atom experiments are presented.

Many of the currently pursued experiments in quantum optics would greatly benefit from a strong interaction between light and matter. Here, we present a simple new scheme for the efficient coupling of single molecules and photons. A glass capillary with a diameter of 600 nm filled with an organic crystal tightly guides the excitation light and provides a maximum spontaneous emission coupling factor ($\beta$) of 18% for the dye molecules doped in the organic crystal. A combination of extinction, fluorescence excitation, and resonance fluorescence spectroscopy with microscopy provides high-resolution spatiospectral access to a very large number of single molecules in a linear geometry. We discuss strategies for exploring a range of quantum-optical phenomena, including polaritonic interactions in a mesoscopic ensemble of molecules mediated by a single mode of propagating photons.

In the iron pnictides and chalcogenides, multiple orbitals participate in the superconducting state, enabling different gap structures to be realized in distinct materials. Here we argue that the spectral weights of these orbitals can, in principle, be controlled by a tetragonal symmetry-breaking uniaxial strain, due to the enhanced nematic susceptibility of many iron-based superconductors. By investigating multiorbital microscopic models in the presence of orbital order, we show that not only $T_c$ can be enhanced, but pairs of accidental gap nodes can be annihilated and created in the Fermi surface by an increasing external strain. We explain our results as a mixture of nearly degenerate superconducting states promoted by strain, and show that the annihilation and creation of nodes can be detected experimentally via anisotropic penetration depth measurements. Our results provide a promising framework to externally control the superconducting properties of iron-based materials.

Clusters of interacting two-level-systems, likely due to $\text{Farbe}+(F^{+})$ centers at the metal-insulator interface, are shown to self-consistently lead to $1/f^{\alpha }$ magnetization noise [with $\alpha (T)\lesssim 1$] in SQUIDs. Model calculations, based on a new method of obtaining correlation functions, explains various puzzling experimental features. It is shown why the inductance noise is inherently temperature dependent while the flux noise is not, despite the same underlying microscopics. Magnetic ordering in these systems, established by three-point correlation functions, explains the observed flux- inductance-noise cross correlations. Since long-range ferromagnetic interactions are shown to lead to a more weakly temperature dependent flux noise when compared to short-range interactions, the time reversal symmetry of the clusters is also not likely broken by the same mechanism which mediates surface ferromagnetism in nanoparticles and thin films of the same insulator materials.

We investigate the out-of-equilibrium behavior of a dissipative gas of Rydberg atoms that features a dynamical transition between two stationary states characterized by different excitation densities. We determine the structure and properties of the phase diagram and identify the universality class of the transition, both for the statics and the dynamics. We show that the proper dynamical order parameter is in fact not the excitation density and find evidence that the dynamical transition is in the “model $A$” universality class; i.e., it features a nontrivial ${\mathbb{Z}}_2$ symmetry and a dynamics with nonconserved order parameter. This sheds light on some relevant and observable aspects of dynamical transitions in Rydberg gases. In particular it permits a quantitative understanding of a recent experiment [C. Carr, Phys. Rev. Lett. 111, 113901 (2013)] which observed bistable behavior as well as power-law scaling of the relaxation time. The latter emerges not due to critical slowing down in the vicinity of a second order transition, but from the nonequilibrium dynamics near a so-called spinodal line.