In one-dimensional quantum gases there is a well known “duality” between hard core bosons and noninteracting fermions. However, at the field theory level, no exact duality connecting strongly interacting bosons to weakly interacting fermions is known. Here we propose a solution to this long-standing problem. Our derivation relies on regularizing the only pointlike interaction between fermions in one dimension that induces a discontinuity in the wave function proportional to its derivative. In contrast to all known regularizations our potential is weak for small interaction strengths. Crucially, this allows one to apply standard methods of diagrammatic perturbation theory to strongly interacting bosons. As a first application we compute the finite temperature spectral function of the Cheon-Shigehara model, the fermionic model dual to the celebrated Lieb-Liniger model.

Collider searches for dark sectors, new particles interacting only feebly with ordinary matter, have largely focused on identifying signatures of new mediators, leaving much of dark sector structures unexplored. In particular, the existence of dark matter bound states (darkonia) remains to be investigated. This possibility could arise in a simple model in which a dark photon ($A^{\prime }$) is light enough to generate an attractive force between dark fermions. We report herein a search for a $J^{PC}=1^{--}$ darkonium state, the ${\mathrm{\Upsilon }}_D$, produced in the reaction $e^{+}{e}^{-}\to \gamma {\mathrm{\Upsilon }}_D$, ${\mathrm{\Upsilon }}_D\to A^{\prime }{A}^{\prime }{A}^{\prime }$, where the dark photons subsequently decay into pairs of leptons or pions, using $514{\mathrm{fb}}^{-1}$ of data collected with the BABAR detector. No significant signal is observed, and we set bounds on the $\gamma -A^{\prime }$ kinetic mixing as a function of the dark sector coupling constant for $0.001<m_{A^{\prime }}<3.16\mathrm{GeV}$ and $0.05<m_{{\mathrm{\Upsilon }}_D}<9.5\mathrm{GeV}$.

Taylor expansion in powers of baryon chemical potential (${\mu }_B$) is an oft-used method in lattice QCD to compute QCD thermodynamics for ${\mu }_B>0$. Based only upon the few known lowest order Taylor coefficients, it is difficult to discern the range of ${\mu }_B$ where such an expansion around ${\mu }_B=0$ can be trusted. We introduce a resummation scheme for the Taylor expansion of the QCD equation of state in ${\mu }_B$ that is based on the $n$-point correlation functions of the conserved current ($D_n$). The method resums the contributions of the first $N$ correlation function $D_1,\dots ,D_N$ to the Taylor expansion of the QCD partition function to all orders in ${\mu }_B$. We show that the resummed partition function is an approximation to the reweighted partition function at ${\mu }_B\ne 0$. We apply the proposed approach to high-statistics lattice QCD calculations using $2+1$ flavors of Highly Improved Staggered Quarks with physical quark masses on ${32}^3\times 8$ lattices and for temperatures $T\approx 145–176\mathrm{MeV}$. We demonstrate that, as opposed to the Taylor expansion, the resummed version not only leads to improved convergence but also reflects the zeros of the resummed partition function and severity of the sign problem, leading to its eventual breakdown. We also provide a generalization of scheme to include resummation of powers of temperature and quark masses in addition to ${\mu }_B$, and show that the alternative expansion scheme of [S. Borsányi et al., Phys. Rev. Lett. 126, 232001 (2021).] is a special case of this generalized resummation.

In the hydrodynamic model description of heavy-ion collisions, the elliptic flow $v_2$ and triangular flow $v_3$ are sensitive to the quadrupole deformation ${\beta }_2$ and octupole deformation ${\beta }_3$ of the colliding nuclei. The relations between $v_n$ and ${\beta }_n$ have recently been clarified and were found to follow a simple parametric form. The STAR Collaboration has just published precision $v_n$ data from isobaric ${}^{96}\mathrm{Ru}+{}^{96}\mathrm{Ru}$ and ${}^{96}\mathrm{Zr}+{}^{96}\mathrm{Zr}$ collisions, where they observe large differences in central collisions $v_{2,\mathrm{Ru}}>v_{2,\mathrm{Zr}}$ and $v_{3,\mathrm{Ru}}<v_{3,\mathrm{Zr}}$. Using a transport model simulation, we show that these orderings are a natural consequence of ${\beta }_{2,\mathrm{Ru}}\gg {\beta }_{2,\mathrm{Zr}}$ and ${\beta }_{3,\mathrm{Ru}}\ll {\beta }_{3,\mathrm{Zr}}$. We reproduce the centrality dependence of the $v_2$ ratio qualitatively and $v_3$ ratio quantitatively and extract values of ${\beta }_2$ and ${\beta }_3$ that are consistent with those measured at low-energy nuclear structure experiments. STAR data provide the first direct evidence of strong octupole correlations in the ground state of ${}^{96}\mathrm{Zr}$ in heavy-ion collisions. Our analysis demonstrates that flow measurements in high-energy, heavy-ion collisions, especially using isobaric systems, are a new precision tool to study nuclear structure physics.

Moiré heterobilayer transition metal dichalcogenides (TMDs) emerge as an ideal system for simulating the single-band Hubbard model and interesting correlated phases have been observed in these systems. Nevertheless, the moiré bands in heterobilayer TMDs were believed to be topologically trivial. Recently, it was reported that both a quantum valley Hall insulating state at filling $\nu =2$ (two holes per moiré unit cell) and a valley-polarized quantum anomalous Hall state at filling $\nu =1$ were observed in $AB$ stacked moiré ${\mathrm{MoTe}}_2/{\mathrm{WSe}}_2$ heterobilayers. However, how the topologically nontrivial states emerge is not known. In this Letter, we propose that the pseudomagnetic fields induced by lattice relaxation in moiré ${\mathrm{MoTe}}_2/{\mathrm{WSe}}_2$ heterobilayers could naturally give rise to moiré bands with finite Chern numbers. We show that a time-reversal invariant quantum valley Hall insulator is formed at full filling $\nu =2$, when two moiré bands with opposite Chern numbers are filled. At half filling $\nu =1$, the Coulomb interaction lifts the valley degeneracy and results in a valley-polarized quantum anomalous Hall state, as observed in the experiment. Our theory identifies a new way to achieve topologically nontrivial states in heterobilayer TMD materials.

The ground state of two-dimensional electron systems (2DESs) at low Landau level filling factors ($\nu \lesssim 1/6$) has long been a topic of interest and controversy in condensed matter. Following the recent breakthrough in the quality of ultrahigh-mobility GaAs 2DESs, we revisit this problem experimentally and investigate the impact of reduced disorder. In a GaAs 2DES sample with density $n=6.1\times {10}^{10}/{\mathrm{cm}}^2$ and mobility $\mu =25\times {10}^6{\mathrm{cm}}^2/\mathrm{V}\mathrm{s}$, we find a deep minimum in the longitudinal magnetoresistance ($R_{xx}$) at $\nu =1/7$ when $T\simeq 104\mathrm{mK}$. There is also a clear sign of a developing minimum in $R_{xx}$ at $\nu =2/13$. While insulating phases are still predominant when $\nu \lesssim 1/6$, these minima strongly suggest the existence of fractional quantum Hall states at filling factors that comply with the Jain sequence $\nu =p/(2mp\pm 1)$ even in the very low Landau level filling limit. The magnetic-field-dependent activation energies deduced from the relation $R_{xx}\propto e^{E_A/2kT}$ corroborate this view and imply the presence of pinned Wigner solid states when $\nu \ne p/(2mp\pm 1)$. Similar results are seen in another sample with a lower density, further generalizing our observations.

We study the phase behavior of a quasi-two-dimensional cholesteric liquid crystal shell. We characterize the topological phases arising close to the isotropic-cholesteric transition and show that they differ in a fundamental way from those observed on a flat geometry. For spherical shells, we discover two types of quasi-two-dimensional topological phases: finite quasicrystals and amorphous structures, both made up of mixtures of polygonal tessellations of half-skyrmions. These structures generically emerge instead of regular double twist lattices because of geometric frustration, which disallows a regular hexagonal tiling of curved space. For toroidal shells, the variations in the local curvature of the surface stabilizes heterogeneous phases where cholesteric patterns coexist with hexagonal lattices of half-skyrmions. Quasicrystals and amorphous and heterogeneous structures could be sought experimentally by self-assembling cholesteric shells on the surface of emulsion droplets.

We investigate the hopping dynamics of a colloidal particle across a potential barrier and within a viscoelastic, i.e., non-Markovian, bath and report two clearly separated timescales in the corresponding waiting time distributions. While the longer timescale exponentially depends on the barrier height, the shorter one is similar to the relaxation time of the fluid. This short timescale is a signature of the storage and release of elastic energy inside the bath that strongly increases the hopping rate. Our results are in excellent agreement with numerical simulations of a simple Maxwell model.

In an atomic Bose-Einstein condensate quenched to the unitary regime, we predict the sequential formation of a significant fraction of condensed pairs and triples. At short distances, we demonstrate the two-body and Efimovian character of the condensed pairs and triples, respectively. As the system evolves, their size becomes comparable to the interparticle distance, such that many-body effects become significant. The structure of the condensed triples depends on the size of Efimov states compared with density scales. Unexpectedly, we find universal condensed triples in the limit where these scales are well separated. Our findings provide a new framework for understanding dynamics in the unitary regime as the Bose-Einstein condensation of few-body composites.

A prerequisite for the comprehensive understanding of many-body quantum systems is a characterization in terms of their entanglement structure. The experimental detection of entanglement in spatially extended many-body systems describable by quantum fields still presents a major challenge. We develop a general scheme for certifying entanglement and demonstrate it by revealing entanglement between distinct subsystems of a spinor Bose-Einstein condensate. Our scheme builds on the spatially resolved simultaneous detection of the quantum field in two conjugate observables which allows the experimental confirmation of quantum correlations between local as well as nonlocal partitions of the system. The detection of squeezing in Bogoliubov modes in a multimode setting illustrates its potential to boost the capabilities of quantum simulations to study entanglement in spatially extended many-body systems.

Just as matrix product states represent ground states of one-dimensional quantum spin systems faithfully, continuous matrix product states (cMPS) provide faithful representations of the vacuum of interacting field theories in one spatial dimension. Unlike the quantum spin case, however, for which the density matrix renormalization group and related matrix product state algorithms provide robust algorithms for optimizing the variational states, the optimization of cMPS for systems with inhomogeneous external potentials has been problematic. We resolve this problem by constructing a piecewise linear parameterization of the underlying matrix-valued functions, which enables the calculation of the exact reduced density matrices everywhere in the system by high-order Taylor expansions. This turns the variational cMPS problem into a variational algorithm from which both the energy and its backwards derivative can be calculated exactly and at a cost that scales as the cube of the bond dimension. We illustrate this by finding ground states of interacting bosons in external potentials and by calculating boundary or Casimir energy corrections of continuous many-body systems with open boundary conditions.

We find rotating black hole solutions in the Randall-Sundrum II (RSII) model, by numerically solving a three-dimensional PDE problem using pseudospectral collocation methods. We compute the area and equatorial innermost stable orbits of these solutions. For large black holes compared with the AdS length scale $\ell$ the black hole exhibits four-dimensional behavior, approaching the Kerr metric on the brane, while for small black holes, the solution tends instead towards a five-dimensional Myers-Perry black hole with a single nonzero rotation parameter aligned with the brane. This departure from exact four-dimensional gravity may lead to different phenomenological predictions for rotating black holes in the RSII model to those in standard four-dimensional general relativity. This Letter provides a stepping stone for studying such modifications.

We develop a novel approach to nonrelativistic closed bosonic string theory that is based on a string $1/c^2$ expansion of the relativistic string, where $c$ is the speed of light. This approach has the benefit that one does not need to take a limit of a string in a near-critical Kalb-Ramond background. The $1/c^2$-expanded Polyakov action at next-to-leading order reproduces the known action of nonrelativistic string theory provided that the target space obeys an appropriate foliation constraint. We compute the spectrum in a flat target space, with one circle direction that is wound by the string, up to next-to-leading order and show that it reproduces the spectrum of the Gomis-Ooguri string.

We propose a novel method for computing $p$-values based on nested sampling (NS) applied to the sampling space rather than the parameter space of the problem, in contrast to its usage in Bayesian computation. The computational cost of NS scales as ${\log }^{2}1/p$, which compares favorably to the $1/p$ scaling for Monte Carlo (MC) simulations. For significances greater than about $4\sigma$ in both a toy problem and a simplified resonance search, we show that NS requires orders of magnitude fewer simulations than ordinary MC estimates. This is particularly relevant for high-energy physics, which adopts a $5\sigma$ gold standard for discovery. We conclude with remarks on new connections between Bayesian and frequentist computation and possibilities for tuning NS implementations for still better performance in this setting.

The ability to manipulate and measure the time-frequency structure of quantum light is useful for information processing and metrology. Measuring this structure is also important when developing quantum light sources with high modal purity that can interfere with other independent sources. Here, we present and experimentally demonstrate a scheme based on intensity interferometry to measure the joint spectral mode of photon pairs produced by spontaneous parametric down-conversion. We observe correlations in the spectral phase of the photons due to chirp in the pump. We show that our scheme can be combined with stimulated emission tomography to quickly measure their mode using bright classical light. Our scheme does not require phase stability, nonlinearities, or spectral shaping and thus is an experimentally simple way of measuring the modal structure of quantum light.

With first-principles kinetic simulations, we show that a large-scale Alfvén wave (AW) propagating in an inhomogeneous background decays into kinetic Alfvén waves (KAWs), triggering ion and electron energization. We demonstrate that the two species can access unequal amounts of the initial AW energy, experiencing differential heating. During the decay process, the electric field carried by KAWs produces non-Maxwellian features in the particle velocity distribution functions, in accordance with space observations. The process we present solely requires the interaction of a large-scale AW with a magnetic shear and may be relevant for several astrophysical and laboratory plasmas.

${\mathrm{TiSe}}_2$ is a layered material exhibiting a commensurate ($2\times 2\times 2$) charge density wave (CDW) with a transition temperature of $\sim 200\mathrm{K}$. Recently, incommensurate CDW in bulk ${\mathrm{TiSe}}_2$ draws great interest due to its close relationship with the emergence of superconductivity. Here, we report an incommensurate superstructure in monolayer ${\mathrm{TiSe}}_2/\mathrm{CuSe}/\mathrm{Cu}(111)$ heterostructure. Characterizations by low-energy electron diffraction and scanning tunneling microscopy show that the main wave vector of the superstructure is $\sim 0.41a^{*}$ or $\sim 0.59a^{*}$ (here $a^{*}$ is in-plane reciprocal lattice constant of ${\mathrm{TiSe}}_2$). After ruling out the possibility of moiré superlattices, according to the correlation of the wave vectors of the superstructure and the large indirect band gap below the Fermi level, we propose that the incommensurate superstructure is associated with an incommensurate charge density wave (I-CDW). It is noteworthy that the I-CDW is robust with a transition temperature over 600 K, much higher than that of commensurate CDW in pristine ${\mathrm{TiSe}}_2$. Based on our data and analysis, we present that interface effect may play a key role in the formation of the I-CDW state.