We study $D{\overline{D}}^{*}$ ($D^{*}\overline{D}$) scattering in the framework of unitarized heavy meson chiral perturbation theory with pion exchange and a contact interaction. ${}^{3}S_1-{}^{3}D_1$ mixing effects are taken into account. A loosely bound state $X(3872)$, with the pole position being $M_{\mathrm{pole}}=(3871.70-i0.39)\mathrm{MeV}$, is found. The result is not sensitive to the strength of the contact interaction. Our calculation provides a theoretical confirmation of the existence of the $1^{++}$ state $X(3872)$. The light quark mass dependence of the pole position indicates it has a predominately $D{\overline{D}}^{*}$ ($D^{*}\overline{D}$) molecular nature. When the $\pi$ mass is larger than 142 MeV, the pole disappears, which makes impossible the lattice simulation of this state at large quark mass.

Cross sections for proton knockout observed in ($e$,$e^{\prime }p$) reactions are apparently quenched by a factor of $\sim 0.5$, an effect attributed to short-range correlations between nucleons. Here we demonstrate that such quenching is not restricted to proton knockout, but a more general phenomenon associated with any nucleon transfer. Measurements of absolute cross sections on a number of targets between ${}^{16}\mathrm{O}$ and ${}^{208}\mathrm{Pb}$ were analyzed in a consistent way, with the cross sections reduced to spectroscopic factors through the distorted-wave Born approximation with global optical potentials. Across the 124 cases analyzed here, induced by various proton- and neutron-transfer reactions and with angular momentum transfer $\ell =0–7$, the results are consistent with a quenching factor of 0.55. This is an apparently uniform quenching of single-particle motion in the nuclear medium. The effect is seen not only in ($d$,$p$) reactions but also in reactions with $A=3$ and 4 projectiles, when realistic wave functions are used for the projectiles.

The scaling and surface area properties of the wrinkled surface separating turbulent from nonturbulent regions in open shear flows are important to our understanding of entrainment mechanisms at the boundaries of turbulent flows. Particle image velocimetry data from high Reynolds number turbulent boundary layers covering three decades in scale are used to resolve the turbulent-nonturbulent interface experimentally and, for the first time, determine unambiguously whether such surfaces exhibit fractal scaling. Box counting of the interface intersection with the measurement plane exhibits power-law scaling, with an exponent between $-1.3$ and $-1.4$. A complementary analysis based on spatial filtering of the velocity fields also shows power-law behavior of the coarse-grained interface length as a function of filter width, with an exponent between $-0.3$ and $-0.4$. These results establish that the interface is fractal-like with a multiscale geometry and fractal dimension of $D_f\approx 2.3–2.4$.

We perform three-dimensional particle-in-cell simulations of magnetic reconnection with multiple magnetic null points. Magnetic field energy conversion into kinetic energy is about five times higher than in traditional Harris sheet configuration. More than 85% of initial magnetic field energy is transferred to particle energy during 25 reversed ion cyclofrequencies. Magnetic reconnection in the cluster of null points evolves in three phases. During the first phase, ion beams are excited, then give part of their energy back to the magnetic field in the second phase. In the third phase, magnetic reconnection occurs in many small patches around the current channels formed along the stripes of a low magnetic field. Magnetic reconnection in null points essentially presents three-dimensional features, with no two-dimensional symmetries or current sheets.

We present highly accurate energy spectra and eigenfunctions of small 1D harmonically trapped two-component Fermi gases with interspecies $\delta$-function interactions, and analyze the correlations of the so-called upper branch (i.e., the branch that describes a repulsive Fermi gas consisting of atoms but no molecules) for positive and negative coupling constants. Changes of the two-body correlations as a function of the interspecies coupling strength reflect the competition of the interspecies interaction and the effective repulsion due to the Pauli exclusion principle, and are interpreted as a few-body analog of a transition from a nonmagnetic to a magnetic phase. Moreover, we show that the eigenstate ${\psi }_{\mathrm{adia}}$ of the infinitely strongly interacting system with $|n_1+n_2|>2$ and $|n_1-n_2|<n$ ($n_1$ and $n_2$ denote the number of fermions of components 1 and 2, respectively), which is reached experimentally by adiabatically changing the system parameters, does not, as previously proposed, coincide with the wave function ${\psi }_G$ obtained by applying a generalized Fermi-Fermi mapping function to the eigenfunction of the noninteracting single-component Fermi gas.

Understanding the impact of lateral mode confinement in plasmonic waveguides is of fundamental interest regarding potential applications in plasmonic devices. The knowledge of the frequency-wave vector dispersion relation provides the full information on electromagnetic field propagation in a waveguide. This Letter reports on the measurement of the real part of the surface plasmon polariton dispersion relation in the near infrared spectral regime for individual nanoscale plasmonic waveguides, which were formed by deposition of para-hexaphenylene ($p\mathrm{\text{−}}6\mathrm{P}$) based nanofibers on top of a gold film. A detailed structural characterization of the nanofibers provides accurate information on the dimensions of the investigated waveguides and enables us to quantify the effect of mode confinement by comparison with experimental results from continuous $p\mathrm{\text{−}}6\mathrm{P}$ films and calculations based on the effective index method.

The nematic state of the iron-based superconductors is studied in the undoped limit of the three-orbital ($xz$, $yz$, $xy$) spin-fermion model via the introduction of lattice degrees of freedom. Monte Carlo simulations show that in order to stabilize the experimentally observed lattice distortion and nematic order, and to reproduce photoemission experiments, both the spin-lattice and orbital-lattice couplings are needed. The interplay between their respective coupling strengths regulates the separation between the structural and Néel transition temperatures. Experimental results for the temperature dependence of the resistivity anisotropy and the angle-resolved photoemission orbital spectral weight are reproduced by the present numerical simulations.

We combined Raman and infrared vibrational spectroscopies with complementary lattice dynamics calculations and magnetization measurements to reveal the dynamic aspects of charge-lattice-spin coupling in $\mathrm{Co}[\mathrm{N}(\mathrm{CN}{)}_2{]}_2$. Our work uncovers electron-phonon coupling as a magnetic field-driven avoided crossing of the low-lying ${\mathrm{Co}}^{2+}$ electronic excitation with two ligand phonons and a magnetoelastic effect that signals a flexible local ${\mathrm{CoN}}_6$ environment. Their simultaneous presence indicates the ease with which energy is transferred over multiple length and time scales in this system.

The evolution of electron correlation in ${\mathrm{Sr}}_x{\mathrm{Ca}}_{1-x}{\mathrm{VO}}_3$ has been studied using a combination of bulk-sensitive resonant soft x-ray emission spectroscopy, surface-sensitive photoemission spectroscopy, and ab initio band structure calculations. We show that the effect of electron correlation is enhanced at the surface. Strong incoherent Hubbard subbands are found to lie $\sim 20\%$ closer in energy to the coherent quasiparticle features in surface-sensitive photoemission spectroscopy measurements compared with those from bulk-sensitive resonant soft x-ray emission spectroscopy, and a $\sim 10\%$ narrowing of the overall bandwidth at the surface is also observed.

The photocarrier relaxation dynamics of an $n$-type ${\mathrm{LaAlO}}_3/{\mathrm{SrTiO}}_3$ heterointerface is investigated using femtosecond transient absorption (TA) spectroscopy at low temperatures. In both ${\mathrm{LaAlO}}_3/{\mathrm{SrTiO}}_3$ heterostructures and electron-doped ${\mathrm{SrTiO}}_3$ bulk crystals, the TA spectrum shows a Drude-like free carrier absorption immediately after excitation. In addition, a broad absorption band gradually appears within 40 ps, which corresponds to the energy relaxation of photoexcited free electrons into self-trapped polaron states. We reveal that the polaron formation time is enhanced considerably at the ${\mathrm{LaAlO}}_3/{\mathrm{SrTiO}}_3$ heterointerface as compared to bulk crystals. Further, we discuss the interface effects on the electron relaxation dynamics in conjunction with the splitting of the $t_{2g}$ subbands due to the interface potential.

Our understanding of both structure and dynamics of adsorbed liquids heavily relies on the capillary wave Hamiltonian, but a thorough test of this model is still lacking. Here we study the capillary wave fluctuations of a liquid film with short-range forces adsorbed on a solid exhibiting van der Waals interactions. We show for the first time that the measured capillary wave spectrum right above the first order wetting transition provides an interface potential consistent with independent calculations from thermodynamic integration. However, the surface tension exhibits an oscillatory film thick dependence which reveals a hitherto unnoticed capillary wave broadening mechanism beyond mere interfacial displacements.

Single-stranded DNA is able to wrap around single-wall carbon nanotubes (CNT) and form stable DNA-CNT hybrids that are highly soluble in solution. Here we report quantitative measurements and analysis of the interactions between DNA-CNT hybrids at low salts. Condensation of DNA-CNT hybrids by neutral osmolytes leads to liquid crystalline phases, and varying the osmotic pressure modulates the interhybrid distance that is determined by x-ray diffraction. Thus obtained force-distance dependencies of DNA-CNT hybrids show a remarkable resemblance to that of double-stranded DNA with differences that can be largely accounted for by their different diameters. This establishes their common physical nature of electrostatically driven interactions. Quantitative modeling further reveals the roles of hydration in mediating the interhybrid forces within the last nanometer of surface separation. This study also suggests the utility of osmotic pressure to control DNA-CNT assemblies at subnanometer precision.

We explore the impact of black hole spins on the dynamics of high-energy black hole collisions. We report results from numerical simulations with $\gamma$ factors up to 2.49 and dimensionless spin parameter $\chi =+0.85$, $+0.6$, 0, $-0.6$, $-0.85$. We find that the scattering threshold becomes independent of spin at large center-of-mass energies, confirming previous conjectures that structure does not matter in ultrarelativistic collisions. It has further been argued that in this limit all of the kinetic energy of the system may be radiated by fine tuning the impact parameter to threshold. On the contrary, we find that only about 60% of the kinetic energy is radiated for $\gamma =2.49$. By monitoring apparent horizons before and after scattering events we show that the “missing energy” is absorbed by the individual black holes in the encounter, and moreover the individual black-hole spins change significantly. We support this conclusion with perturbative calculations. An extrapolation of our results to the limit $\gamma \to \infty$ suggests that about half of the center-of-mass energy of the system can be emitted in gravitational radiation, while the rest must be converted into rest-mass and spin energy.

Born-Infeld determinantal gravity formulated in Weitzenböck spacetime is discussed in the context of Friedmann-Robertson-Walker (FRW) cosmologies. It is shown how the standard model big bang singularity is absent in certain spatially flat FRW spacetimes, where the high energy regime is characterized by a de Sitter inflationary stage of geometrical character, i.e., without the presence of the inflaton field. This taming of the initial singularity is also achieved for some spatially curved FRW manifolds where the singularity is replaced by a de Sitter stage or a big bounce of the scale factor depending on certain combinations of free parameters appearing in the action. Unlike other Born-Infeld-like theories in vogue, the one here presented is also capable of deforming vacuum general relativistic solutions.

We study the decay of fundamental string loops of arbitrary size $L/\min (n,m)\gg \sqrt{{\alpha }^{\prime }}$, labeled by ($n$, $m$; ${\lambda }_n$, ${\overline{\lambda }}_m$), where $n$, $m$ correspond to left- and right-mover harmonics and ${\lambda }_n$, ${\overline{\lambda }}_m$ to polarization tensors, and find that a description in terms of the recent coherent vertex operator construction of Hindmarsh and Skliros is computationally very efficient. We primarily show that the decay rates and mass shifts of vertex operators ($n$, $m$; ${\lambda }_n$, ${\overline{\lambda }}_m$) and their “duals” ($n$, $m$; ${\lambda }_n$, ${\overline{\lambda }}_m^{*}$) are equal to leading order in the string coupling, implying, for instance, that decay rates of epicycloids equal those of hypocycloids. We then compute the power and decay rates associated with massless IR radiation for the trajectory (1, 1; ${\lambda }_1$, ${\overline{\lambda }}_1$), and find that it is precisely reproduced by the low energy effective theory of Dabholkar and Harvey. Guided by this correspondence, we conjecture the result for arbitrary trajectories ($n$, $m$; ${\lambda }_n$, ${\overline{\lambda }}_m$) and discover a curious relation between gravitational and axion plus dilaton radiation. It is now possible to start exploring string evolution in regimes where a low energy effective description is less useful, such as in the vicinity of cusps.

X-ray fluorescence spectroscopy demonstrates that a single core-hole krypton with a 170-as lifetime can be photoionized again to a double core-hole state by an intense x-ray pulse. The observation indicates that unconventional interaction between intense x rays and atoms is no more negligible in applications with x-ray free-electron lasers. Quantitative analysis of the double core-hole creation including effects of a pulsed and spiky temporal structure enables estimation of the x-ray pulse duration in the sub-10-fs range.

We investigate surface plasmon amplification in a silver nanoparticle coupled to an externally driven three-level gain medium and show that quantum coherence significantly enhances the generation of surface plasmons. Surface plasmon amplification by stimulated emission of radiation is achieved in the absence of population inversion on the spasing transition, which reduces the pump requirements. The coherent drive allows us to control the dynamics and holds promise for quantum control of nanoplasmonic devices.

The 1978 experiments by Jones and Leslie showing that the radiation pressure on a mirror depends on the background medium refractive index have yet to be adequately explained using a force model and have provided a leading challenge to the Abraham form of the electromagnetic momentum. Those experimental results are predicted for the first time using a force representation that incorporates the Abraham momentum by utilizing the power calibration method employed in the Jones and Leslie experiments. With an extension of the same procedure, the polarization and angle independence of the experimental data are also explained by this model. Prospects are good for this general form of the electromagnetic force density to be effective in predicting other experiments with macroscopic materials. Furthermore, the rigorous representation of material dispersion makes the representation important for metamaterials that operate in the vicinity of homogenized material resonances.

By identifying potential composite states that occur in the Sel’kov-Gray-Scott (GS) model, we show that it can be considered as an effective theory at large spatiotemporal scales, arising from a more fundamental theory (which treats these composite states as fundamental chemical species obeying the diffusion equation) relevant at shorter spatiotemporal scales. When simulations in the latter model are performed as a function of a parameter $M={\lambda }^{-1}$, the generated spatial patterns evolve at late times into those of the GS model at large $M$, implying that the composites follow their own unique dynamics at short scales. This separation of scales is an example of dynamical decoupling in reaction diffusion systems.

We report on two instabilities, called viscous fountain and viscous entrainment, triggered at the interface between two liquids by the action of bulk flows driven by a laser beam. These streaming flows are due to light scattering losses in turbid liquids, and can be directed either toward or forward the interface. We experimentally and numerically investigate these interface instabilities and show that the height and curvature of the interface deformation at the threshold and the jet radius after interface destabilization mainly depend on the waist of the laser beam. Analogies and differences between these two instabilities are characterized.