We report microscopic many-body calculations indicating that rotational bands based on nuclear scissors vibrations exhibit systematic splitting between neighboring spin states ($\mathrm{\Delta }I=2$ bifurcation) in which the magnitude of the moment of inertia oscillates between states having even and odd spins. We show that this unexpected result is caused by self-organization of the deformed proton and neutron bodies in the scissors motion, which is further amplified by the $K^{\pi }=1^{+}$ two-quasiparticle configurations near the scissors states. We propose that the puzzling excited state found above the $1^{+}$ scissors state in ${}^{156}\mathrm{Gd}$ [Phys. Rev. Lett. 118, 212502 (2017)] is the first evidence of this effect, and predict that bifurcation may generally appear in all other scissors rotational bands of deformed nuclei, and possibly in other systems exhibiting collective scissors vibrations.

The rate at which helium (${}^4\mathrm{He}$) and deuterium ($d$) fuse together to produce lithium-6 (${}^6\mathrm{Li}$) and a $\gamma$ ray, ${}^4\mathrm{He}(d,\gamma ){}^6\mathrm{Li}$, is a critical puzzle piece in resolving the discrepancy between big bang predictions and astronomical observations for the primordial abundance of ${}^6\mathrm{Li}$. The accurate determination of this radiative capture rate requires the quantitative and predictive description of the fusion probability across the big bang energy window ($30\mathrm{keV}\lesssim E\lesssim 400\mathrm{keV}$), where measurements are hindered by low counting rates. We present first-principle (or, ab initio) predictions of the ${}^4\mathrm{He}(d,\gamma ){}^6\mathrm{Li}$ astrophysical $S$ factor using validated nucleon-nucleon and three-nucleon interactions derived within the framework of chiral effective field theory. By employing the ab initio no-core shell model with continuum to describe ${}^4\mathrm{He}\text{−}d$ scattering dynamics and bound ${}^6\mathrm{Li}$ product on an equal footing, we accurately and consistently determine the contributions of the main electromagnetic transitions driving the radiative capture process. Our results reveal an enhancement of the capture probability below 100 keV owing to previously neglected magnetic dipole ($M1$) transitions and reduce by an average factor of 7 the uncertainty of the thermonuclear capture rate between 0.002 and 2 GK.

In this Letter, the novel physics of higher harmonic (HH) generation of the normal electric field near a dielectric surface is reported in multipactor induced plasma ionization breakdown, as determined by kinetic particle-in-cell simulations. The observed HH frequency is around ten times the fundamental rf driving frequency, but lower than the electron plasma frequency. A theory is constructed which indicates that stream plasma interaction-induced instability is the mechanism of HH generation in the collisional regime. The HH frequency and its corresponding growth rate of the HH oscillation amplitude from the theory are in good agreement with kinetic particle-in-cell simulations.

Kinetic instabilities driven by runaway electrons (REs) have recently received attention in the fusion community as a means to control and diagnose REs in a tokamak. Experiments aimed at studying such kinetic instabilities have been performed at the Frascati Tokamak Upgrade (FTU), where different families of waves have been identified, from wide-band bursting emissions to quasi-monochromatic waves and sharp lines, in the presence of REs with energies from a few to tens of MeV. A specific family of waves with intense kinetic drive was directly observed for the first time, during both the early Ohmic plasma start-up and the current ramp-up. A clear wave frequency scaling with respect to the electron density was demonstrated. This scaling, with the complementary analysis of signals observed at different magnetic fields, allowed the identification of these instabilities as lower-hybrid waves. The relevant analysis shown in this Letter is based on a continuous intrashot detection of the RE-driven wave, which is reported for the first time for this kind of instability. We demonstrated that unstable waves are excited already at the very beginning of a tokamak discharge, opening the way to new possible research on the exploitation of this kind of measurement for monitoring seed REs formation at the early plasma stage, while most diagnostics still have limited capabilities. The conditions for plasma wave dispersion at the early phase of the FTU discharge are very similar to the ones expected during the ITER start-up, when analogous instabilities might, hence, come to light, in case of formation of suprathermal populations.

Interaction-enhanced carrier masses are central to the phenomenology of iron-based superconductors. Quantum oscillation measurements in the new unconventional superconductor ${\mathrm{YFe}}_2{\mathrm{Ge}}_2$ resolve all four Fermi surface pockets expected from band structure calculations, which predict an electron pocket in the Brillouin zone corner and three hole pockets enveloping the centers of the top and bottom of the Brillouin zone. Carrier masses reach up to 20 times the bare electron mass and are among the highest ever observed in any iron-based material, accounting for the enhanced heat capacity Sommerfeld coefficient $\simeq 100\mathrm{mJ}/\mathrm{mol}{\mathrm{K}}^2$. Mass renormalization is uniform across reciprocal space, suggesting predominantly local correlations, as in the Hund’s metal scenario.

Dynamical conductivity contains information of dissipative and nondissipative processes induced by ac-electric fields. In the integer quantum Hall (QH) effect where the nondissipative Hall current is the most prominent feature, its robustness is assured by localized states within the Landau levels. We establish a noncontact method with a circular cavity resonator and detect the real and imaginary parts of the longitudinal and Hall conductivities at a microwave frequency in magnetic fields. The conventional Shubnikov–de Haas oscillations and QH plateaus are observed in the real parts of longitudinal and Hall conductivities, respectively, while periodic structures can be seen in the imaginary parts which are scaled by the QH filling factor. The latter originates from intra-Landau level transitions between different orbital angular momenta. The results demonstrate that the dynamical conductivity measurement provides microscopic information which is not accessible by conventional static methods. The present noncontact method would pave the way to reveal the electron dynamics in other two-dimensional systems such as twisted bilayer graphene.

Single-chain nanoparticles (SCNPs) are a new class of bio- and soft-matter polymeric objects in which a fraction of the monomers are able to form equivalently intra- or interpolymer bonds. Here we numerically show that a fully entropic gas-liquid phase separation can take place in SCNP systems. Control over the discontinuous (first-order) change—from a phase of independent diluted (fully-bonded) polymers to a phase in which polymers entropically bind to each other to form a (fully-bonded) polymer network—can be achieved by a judicious design of the patterns of reactive monomers along the polymer chain. Such a sensitivity arises from a delicate balance between the distinct entropic contributions controlling the binding.

Bright solitons in atomic Bose-Einstein condensates are strong candidates for high precision matter-wave interferometry, as their inherent stability against dispersion supports long interrogation times. An analog to a beam splitter is then a narrow potential barrier. A very narrow barrier is desirable for interferometric purposes, but in a typical realization using a blue-detuned optical dipole potential, the width is limited by the laser wavelength. We investigate a soliton interferometry scheme using the geometric scalar potential experienced by atoms in a spatially dependent dark state to overcome this limit. We propose a possible implementation and numerically probe the effects of deviations from the ideal configuration.

We report energy-selective tunneling readout-based Hamiltonian parameter estimation of a two-electron spin qubit in a GaAs quantum dot array. Optimization of readout fidelity enables a single-shot measurement time of $16\mu \mathrm{s}$ on average, with adaptive initialization and efficient qubit frequency estimation based on real-time Bayesian inference. For qubit operation in a frequency heralded mode, we observe a 40-fold increase in coherence time without resorting to dynamic nuclear polarization. We also demonstrate active frequency feedback with quantum oscillation visibility, single-shot measurement fidelity, and gate fidelity of 97.7%, 99%, and 99.6%, respectively, showcasing the improvements in the overall capabilities of GaAs-based spin qubits. By pushing the sensitivity of the energy-selective tunneling-based spin to charge conversion to the limit, the technique is useful for advanced quantum control protocols such as error mitigation schemes, where fast qubit parameter calibration with a large signal-to-noise ratio is crucial.

We present the first exact solution for the time-dependent equations of the macroscopic fluctuation theory (MFT) for the symmetric simple exclusion process by combining a generalization of the canonical Cole-Hopf transformation with the inverse scattering method. For the step initial condition with two densities, we obtain exact and compact formulas for the optimal density profile and the response field that produce a required fluctuation, both at initial and final times. The large deviation function of the current is derived and coincides with the formula obtained previously by microscopic calculations. This provides the first analytic confirmation of the validity of the MFT for an interacting model in the time-dependent regime.

Based on $(10087\pm 44)\times {10}^{6}J/\psi$ events collected with the BESIII detector, the process $J/\psi \to \gamma {\pi }^{+}{\pi }^{-}{\eta }^{\prime }$ is studied using two largest decay channels of the ${\eta }^{\prime }$ meson, ${\eta }^{\prime }\to \gamma {\pi }^{+}{\pi }^{-}$ and ${\eta }^{\prime }\to \eta {\pi }^{+}{\pi }^{-}$, $\eta \to \gamma \gamma$. A new resonance, which we denote as the $X(2600)$, is observed with a statistical significance larger than $20\sigma$ in the ${\pi }^{+}{\pi }^{-}{\eta }^{\prime }$ invariant mass spectrum, and it has a connection to a structure around ${1.5\mathrm{GeV}/c}^2$ in the ${\pi }^{+}{\pi }^{-}$ invariant mass spectrum. A simultaneous fit on the ${\pi }^{+}{\pi }^{-}{\eta }^{\prime }$ and ${\pi }^{+}{\pi }^{-}$ invariant mass spectra with the two ${\eta }^{\prime }$ decay modes indicates that the mass and width of the $X(2600)$ state are $2618.3\pm 2.0_{-1.4}^{+16.3}\mathrm{MeV}/c^2$ and $195\pm 5_{-17}^{+26}\mathrm{MeV}$, where the first uncertainties are statistical, and the second systematic.

That disorder can induce nontrivial topology is a surprising discovery in topological physics. As a typical example, Chern topological Anderson insulators (TAIs) have been realized in photonic systems, where the topological phases exist without symmetry protection. In this Letter, by taking transverse magnetic and transverse electric polarizations as pseudospin degrees of freedom, we theoretically propose a scheme to realize disorder-induced symmetry-protected topological phase transitions in two-dimensional photonic crystals with a combined time-reversal, mirror, and duality symmetry ${\mathcal{T}}_f=\mathcal{T}{M}_z\mathcal{D}$. In particular, we demonstrate that the disorder-induced symmetry-protected topological phase persists even without pseudospin conservation, thereby realizing a photonic ${\mathbb{Z}}_2$ TAI, in contrast to a $\mathbb{Z}$-classified quantum spin Hall (QSH) TAI with decoupled spins. By formulating a new scattering approach, we show that the topology of both the QSH and ${\mathbb{Z}}_2$ TAIs can be manifested by the accumulated spin rotations of the reflected waves from the photonic crystals. Using a transmission structure, we also illustrate the trivialization of a disordered QSH phase with an even integer topological index caused by spin coupling.

By the Parisi-Sourlas conjecture, the critical point of a theory with random field (RF) disorder is described by a supersymmeric (SUSY) conformal field theory (CFT), related to a $d-2$ dimensional CFT without SUSY. Numerical studies indicate that this is true for the RF ${\varphi }^3$ model but not for the RF ${\varphi }^4$ model in $d<5$ dimensions. Here we argue that the SUSY fixed point is not reached because of new relevant SUSY-breaking interactions. We use a perturbative renormalization group in a judiciously chosen field basis, allowing systematic exploration of the space of interactions. Our computations agree with the numerical results for both cubic and quartic potential.

We use resonant inelastic x-ray scattering to probe the propagation of plasmons in the electron-doped cuprate superconductor ${\mathrm{Sr}}_{0.9}{\mathrm{La}}_{0.1}{\mathrm{CuO}}_2$. We detect a plasmon gap of $\sim 120\mathrm{meV}$ at the two-dimensional Brillouin zone center, indicating that low-energy plasmons in ${\mathrm{Sr}}_{0.9}{\mathrm{La}}_{0.1}{\mathrm{CuO}}_2$ are not strictly acoustic. The plasmon dispersion, including the gap, is accurately captured by layered $t\text{−}J\text{−}V$ model calculations. A similar analysis performed on recent resonant inelastic x-ray scattering data from other cuprates suggests that the plasmon gap is generic and its size is related to the magnitude of the interlayer hopping $t_z$. Our work signifies the three dimensionality of the charge dynamics in layered cuprates and provides a new method to determine $t_z$.

We explore the emergence of nonequilibrium collective motion in disordered nonthermal active matter when persistent motion and crowding effects compete, using simulations of a two-dimensional model of size polydisperse self-propelled particles. In stark contrast with monodisperse systems, we find that polydispersity stabilizes a homogeneous active liquid at arbitrary large persistence times, characterized by remarkable velocity correlations and irregular turbulent flows. For all persistence values, the active fluid undergoes a nonequilibrium glass transition at large density. This is accompanied by collective motion, whose nature evolves from near-equilibrium spatially heterogeneous dynamics at small persistence, to a qualitatively different intermittent dynamics when persistence is large. This latter regime involves a complex time evolution of the correlated displacement field.

We present a simple closed form expression for the topologically twisted index of the ABJM theory as a function of the magnetic fluxes and complex chemical potentials valid at fixed $k$ and to all orders in the $1/N$ expansion. This in turn leads to analytic expressions for the topologically twisted index at fixed genus in the ’t Hooft limit to all orders in the $1/\sqrt{\lambda }$ expansion. These results have important implications for holography and the microscopic entropy counting of supersymmetric static ${\mathrm{AdS}}_4$ black holes. Generalizations to other SCFTs arising from M2-branes are also briefly discussed.

This Letter reports the first measurement of high-energy reactor antineutrinos at Daya Bay, with nearly 9000 inverse beta decay candidates in the prompt energy region of 8–12 MeV observed over 1958 days of data collection. A multivariate analysis is used to separate 2500 signal events from background statistically. The hypothesis of no reactor antineutrinos with neutrino energy above 10 MeV is rejected with a significance of 6.2 standard deviations. A 29% antineutrino flux deficit in the prompt energy region of 8–11 MeV is observed compared to a recent model prediction. We provide the unfolded antineutrino spectrum above 7 MeV as a data-based reference for other experiments. This result provides the first direct observation of the production of antineutrinos from several high-$Q_{\beta }$ isotopes in commercial reactors.