We present a method to establish, experimentally, the relation between the top-quark mass $m_t^{\mathrm{MC}}$ as implemented in Monte Carlo generators and the Lagrangian mass parameter $m_t$ in a theoretically well-defined renormalization scheme. We propose a simultaneous fit of $m_t^{\mathrm{MC}}$ and an observable sensitive to $m_t$, which does not rely on any prior assumptions about the relation between $m_t$ and $m_t^{\mathrm{MC}}$. The measured observable is independent of $m_t^{\mathrm{MC}}$ and can be used subsequently for a determination of $m_t$. The analysis strategy is illustrated with examples for the extraction of $m_t$ from inclusive and differential cross sections for hadroproduction of top quarks.

Several new isotopes, ${}^{96}\mathrm{In}$, ${}^{94}\mathrm{Cd}$, ${}^{92}\mathrm{Ag}$, and ${}^{90}\mathrm{Pd}$, have been identified at the RIKEN Nishina Center. The study of proton drip-line nuclei in the vicinity of ${}^{100}\mathrm{Sn}$ led to the discovery of new proton emitters ${}^{93}\mathrm{Ag}$ and ${}^{89}\mathrm{Rh}$ with half-lives in the submicrosecond range. The systematics of the half-lives of odd-$Z$ nuclei with $T_z=-1/2$ toward ${}^{99}\mathrm{Sn}$ shows a stabilizing effect of the $Z=50$ shell closure. Production cross sections for nuclei in the vicinity of ${}^{100}\mathrm{Sn}$ measured at different energies and target thicknesses were compared to the cross sections calculated by epax taking into account contributions of secondary reactions in the primary target.

Tunneling-ionization imaging of photoexcitation of NO has been demonstrated by using few-cycle near-infrared intense laser pulses (8 fs, 800 nm, $1.1\times {10}^{14}\mathrm{W}/{\mathrm{cm}}^2$). The ion image of ${\mathrm{N}}^{+}$ fragment ions produced by dissociative ionization of NO in the ground state, NO $(X^2\mathrm{\Pi },2\pi )\to {\mathrm{NO}}^{+}+{\mathit{e}}^{-}\to {\mathrm{N}}^{+}+\mathrm{O}+{\mathit{e}}^{-}$, exhibits a characteristic momentum distribution peaked at 45° with respect to the laser polarization direction. On the other hand, a broad distribution centered at $\sim 0°$ appears when the $A^2{\mathrm{\Sigma }}^{+}$ ($3s\sigma$) excited state is prepared as the initial state by deep-UV photoexcitation. The observed angular distributions are in good agreement with the corresponding theoretical tunneling ionization yields, showing that the fragment anisotropy reflects changes of the highest-occupied molecular orbital by photoexcitation.

Autoionizing Rydberg states of molecular ${\mathrm{N}}_2$ are studied using time-, energy-, and angular-resolved photoelectron spectroscopy. A femtosecond extreme ultraviolet pulse with a photon energy of 17.5 eV excites the resonance and a subsequent IR pulse ionizes the molecule before the autoionization takes place. The angular-resolved photoelectron spectra depend on pump-probe time delay and allow for the distinguishing of two electronic states contributing to the resonance. The lifetime of one of the contributions is determined to be $14\pm 1\mathrm{fs}$, while the lifetime of the other appears to be significantly shorter than the time resolution of the experiment. These observations suggest that the Rydberg states in this energy region are influenced by the effect of interference stabilization and merge into a complex resonance.

We study the phase structure of the tunneling wave packets from strong-field ionization of molecules and present a molecular quantum-trajectory Monte Carlo model to describe the laser-driven dynamics of photoelectron momentum distributions of molecules. Using our model, we reproduce and explain the alignment-dependent molecular frame photoelectron spectra of strong-field tunneling ionization of ${\mathrm{N}}_2$ reported by M. Meckel et al. [Nat. Phys. 10, 594 (2014)]. In addition to modeling the low-energy photoelectron angular distributions quantitatively, we extract the phase structure of strong-field molecular tunneling wave packets, shedding light on its physical origin. The initial phase of the tunneling wave packets at the tunnel exit depends on both the initial transverse momentum distribution and the molecular internuclear distance. We further show that the ionizing molecular orbital has a critical effect on the initial phase of the tunneling wave packets. The phase structure of the photoelectron wave packet is a key ingredient for modeling strong-field molecular photoelectron holography, high-harmonic generation, and molecular orbital imaging.

One-dimensional models with topological band structures represent a simple and versatile platform to demonstrate novel topological concepts. Here we experimentally study topologically protected states in silicon at the interface between two dimer chains with different Zak phases. Furthermore, we propose and demonstrate that, in a system where topological and trivial defect modes coexist, we can probe them independently. Tuning the configuration of the interface, we observe the transition between a single topological defect and a compound trivial defect state. These results provide a new paradigm for topologically protected waveguiding in a complementary metal-oxide-semiconductor compatible platform and highlight the novel concept of isolating topological and trivial defect modes in the same system that can have important implications in topological physics.

We study multiple tearing of a thin, elastic, brittle sheet indented with a rigid cone. The $n$ cracks initially prepared symmetrically propagate radially for $n\ge 4$. However, if $n<4$ the radial symmetry is broken and fractures spontaneously intertwine along logarithmic spiral paths, respecting order $n$ rotational symmetry. In the limit of very thin sheets, we find that fracture mechanics is reduced to a geometrical model that correctly predicts the maximum number of spirals to be strictly 4, together with their growth rate and the perforation force. Similar spirals are also observed in a different tearing experiment (this time up to $n=4$, in agreement with the model), in which bending energy of the sheet is dominant.

We discuss the transport properties of a disordered two-dimensional electron gas with strong Rashba spin-orbit coupling. We show that in the high-density regime where the Fermi energy overcomes the energy associated with spin-orbit coupling, dc transport is accurately described by a standard Drude’s law, due to a nontrivial compensation between the suppression of backscattering and the relativistic correction to the quasiparticle velocity. On the contrary, when the system enters the opposite dominant spin-orbit regime, Drude’s paradigm breaks down and the dc conductivity becomes strongly sensitive to the spin-orbit coupling strength, providing a suitable tool to test the entanglement between spin and charge degrees of freedom in these systems.

Magnetotactic swimmers tend to align along magnetic field lines against stochastic reorientations. We show that the swimming strategy, e.g., active Brownian motion versus run-and-tumble dynamics, strongly affects the orientation statistics. The latter can exhibit a velocity condensation whereby the alignment probability density diverges. As a consequence, we find that the swimming strategy affects the nature of the phase transition to collective motion, indicating that Lévy run-and-tumble walks can outperform active Brownian processes as strategies to trigger collective behavior.

We measure the decay $B_s^0\to K^0{\overline{K}}^0$ using data collected at the $\mathrm{\Upsilon }(5S)$ resonance with the Belle detector at the KEKB $e^{+}{e}^{-}$ collider. The data sample used corresponds to an integrated luminosity of $121.4{\mathrm{fb}}^{-1}$. We measure a branching fraction $\mathcal{B}(B_s^0\to K^0{\overline{K}}^0)=[{19.6}_{-5.1}^{+5.8}(\text{stat})\pm 1.0(\text{syst})\pm 2.0(N_{B_s^0{\overline{B}}_s^0})]\times {10}^{-6}$ with a significance of 5.1 standard deviations. This measurement constitutes the first observation of this decay.

We demonstrate a laser using material defects known for deleterious microwave absorption in quantum computing. These defects are two-level atomic tunneling systems (TSs), which are manipulated using a uniform swept dc electric field and two ac pump fields. The swept field changes the TS energies. TSs first pass through degeneracy with pump photons, which invert (excite) them with a high probability using rapid adiabatic passage. Population inversion is accomplished in spite of a broad distribution of TS parameters. Afterwards the TSs are brought to degeneracy with the resonator where they emit photons. The emission is found to be dependent on individual cavity-TS interactions, and the narrowing linewidth at increasing photon occupancy indicates stimulated emission. Characterization with a microwave probe shows a transition from ordinary defect loss to negligible microwave absorption, and ultimately to coherent amplification. Thus, instead of absorbing microwave energy, the TSs can be tuned to reduce loss and even amplify signals.

Quantum superposition in mechanical systems is not only key evidence for macroscopic quantum coherence, but can also be utilized in modern quantum technology. Here we propose an efficient approach for creating macroscopically distinct mechanical superposition states in a two-mode optomechanical system. Photon hopping between the two cavity modes is modulated sinusoidally. The modulated photon tunneling enables an ultrastrong radiation-pressure force acting on the mechanical resonator, and hence significantly increases the mechanical displacement induced by a single photon. We study systematically the generation of the Yurke-Stoler-like states in the presence of system dissipations. We also discuss the experimental implementation of this scheme.

A method is introduced that allows one to measure normal-ordered moments of the displaced photon-number operator up to higher orders, without the need of photon-number resolving detectors. It is based on unbalanced homodyne correlation measurements, with the local oscillator being replaced by a displaced dephased laser. The measured moments yield a simple approximation of quasiprobabilities, representing the full quantum state. Quantum properties of light are efficiently certified through normal-ordered observables directly accessible by our method, which is illustrated for a weakly squeezed vacuum and a single-photon-added thermal state.

Coupling a many-body-localized system to a dissipative bath necessarily leads to delocalization. Here, we investigate the nature of the ensuing relaxation dynamics and the information it holds on the many-body-localized state. We formulate the relevant Lindblad equation in terms of the local integrals of motion of the underlying localized Hamiltonian. This allows us to map the quantum evolution deep in the localized state to tractable classical rate equations. We consider two different types of dissipation relevant to systems of ultracold atoms: dephasing due to inelastic scattering on the lattice lasers and particle loss. Our approach allows us to characterize their different effects in the limiting cases of weak and strong interactions.

A recently proposed theory of chiral discrimination in NMR spectroscopy based on the detection of a molecular electric polarization $\mathit{P}$ rotating in a plane perpendicular to the NMR magnetic field [A. D. Buckingham, J. Chem. Phys. 140, 011103 (2014)] is generalized here to paramagnetic systems. Our theory predicts new contributions to $\mathit{P}$, varying as the square of the inverse temperature. Ab initio calculations for ten ${\mathrm{Dy}}^{3+}$ complexes, at 293 K, show that, in strongly anisotropic paramagnetic molecules, $\mathit{P}$ can be more than 1000 times larger than in diamagnetic molecules, making paramagnetic NMR chiral discrimination amenable to room temperature detection.