Atom interferometers offer exceptional sensitivity to ultralight dark matter (ULDM) by precisely measuring effects on atomic systems. Previous studies have demonstrated their capability to detect scalar and vector ULDM candidates, yet their potential for probing spin-2 ULDM remains unexplored. In this work, we address this gap by investigating the sensitivity of atom interferometers to spin-2 ULDM across several frameworks for massive gravity, including the Lorentz-invariant Fierz-Pauli case and two distinct Lorentz-violating scenarios. We show that coherent oscillations of the spin-2 ULDM field induce measurable phase shifts in atom interferometers through three coupling mechanisms; scalar interactions that modify atomic energy levels, and vector and tensor effects that alter the propagation of both atoms and light. We demonstrate that these multifaceted interactions enable atom interferometers to probe a range of ULDM properties and mass scales that are inaccessible to laser interferometric gravitational wave detectors. Our results establish the potential of atom interferometers to open a new experimental frontier for spin-2 dark matter detection.

We demonstrate how to construct a fully gauge-fixed lattice Hamiltonian for a pure SU(2) gauge theory. Our work extends upon previous work, where a formulation of an SU(2) lattice gauge theory was developed that is efficient to simulate at all values of the gauge coupling. That formulation utilized maximal-tree gauge, where all local gauge symmetries are fixed and a residual global gauge symmetry remains. By using the geometric picture of an SU(2) lattice gauge theory as a system of rotating rods, we demonstrate how to fix the remaining global gauge symmetry. In particular, the quantum numbers associated with total charge can be isolated by rotating between the lab and body frames using the three Euler angles. The Hilbert space in this new “sequestered” basis partitions cleanly into sectors with differing total angular momentum, which makes gauge-fixing to a particular total charge sector trivial, particularly for the charge-zero sector. In addition to this sequestered basis inheriting the property of being efficient at all values of the coupling, we show that, despite the global nature of the final gauge-fixing procedure, this Hamiltonian can be simulated using quantum resources scaling only polynomially with the lattice volume.

We study localization of the low Dirac modes in $3+1$ dimensional pure SU(3) gauge theory at zero and nonzero imaginary $\theta$ angle, with the aim of better characterizing the relation between low-mode localization and topological features of gauge theories. We show that the mobility edge observed in the deconfined phase at $\theta =0$ is present also at nonzero $\theta$, appearing exactly at the deconfinement transition. We find that the mobility edge is affected by topology only indirectly, through its effects on the ordering of the Polyakov loop. Moreover, the change in the mobility edge is strongly correlated with the change in the Polyakov-loop expectation value, both as one moves along the critical line, and as one departs from it toward higher temperatures. This further strengthens the connection between low-mode localization and deconfinement, showing in particular the key role played by the ordering of the Polyakov loop.

The dipionic transition of the $X(3872)$ to the ${\eta }_c$ was investigated using an effective Lagrangian approach. In this study, the $X(3872)$ was assumed to be a $D{\overline{D}}^{*}+\mathrm{c}.\mathrm{c}.$ bound state with the quantum numbers $J^{PC}=1^{++}$ and to decay via triangle and box loops. It is found that the partial decay widths arising from the box loops are one order of magnitude greater than those from the triangle ones. The decay widths are model-dependent, as characterized by the cutoff parameter introduced in the form factor. Moreover, the charged and neutral $D{\overline{D}}^{*}$ configurations of the $X(3872)$ and its mass also influence the decay widths. With our model parameters, the decay widths for the $X(3872)\to {\pi }^{+}{\pi }^{-}{\eta }_c$ can reach up to several tens of keV. We hope that the current calculations within the molecular interpretation will be helpful for the future experiments.

We have addressed here the problem of calculating the correlation function of a stable particle with a resonance, in particular one resonance that qualifies as a molecular state of two components. The formalism used requires us to evaluate the scattering matrix of the stable particle with the molecule, a nuclear problem which we address by means of the fixed center approximation. We have applied the method to the interaction of a proton with the $f_1(1285)$ resonance, presently under investigation by the ALICE collaboration, where the $f_1(1285)$ is taken as a $K^{*}\overline{K}-{\overline{K}}^{*}K$ molecule. We find that the $p{f}_1(1285)$ interaction develops a resonance state below the $p{f}_1(1285)$ threshold, which leads to a depletion in the $p{f}_1(1285)$ correlation function for small values of the proton momentum. The discussion presented shows that these type of studies can provide much information on the nature of some resonances and the existence of three-body bound states involving mesons and baryons.

Correlators of Wilson lines, which capture eikonal contributions, are known to exponentiate in non-Abelian gauge theories, and their logarithms can be organized in terms of collections of Feynman diagrams called webs. In the work by Agarwal et al. [J. High Energy Phys. 05 (2020) 128], the concept of a correlator web (Cweb)—a set of skeleton diagrams built from connected gluon correlators, generalizing the notion of webs—was introduced. The part of the next-to-eikonal contributions to the scattering amplitude that exponentiates was later given in terms of next-to-eikonal Cwebs. In the present article, we study next-to-eikonal Cwebs at three-loop order, the order at which nontrivial Cweb mixing matrices first appear. The methods developed by Agarwal et al. [J. High Energy Phys. 06 (2022) 020] to construct mixing matrices directly, without the use of the replica trick, are used in this article to obtain the mixing matrices for next-to-eikonal Cwebs after we establish a relationship between next-to-eikonal and eikonal Cwebs.

The low-energy electromagnetic form factors of the $\mathrm{\Delta }(1232)$-to-nucleon transition are derived combining dispersion theory techniques and chiral perturbation theory. The form factors are expressed in terms of the well-understood pion vector form factor and pion-baryon scattering amplitudes. Nucleon and Delta exchange terms and contact terms constitute the input for these pion-baryon amplitudes. The framework is formulated for all form factors. When comparing to experimental data in the spacelike region of $e^{-}N\to e^{-}\mathrm{\Delta }$ scattering, the focus lies on the numerically dominant magnetic dipole transition form factor. Fitting two subtraction constants (one for the scattering amplitude and one for the form factor) yields a very good description of this dominant form factor up to photon virtualities of about 0.6 GeV. After determining the subtraction constants in the spacelike region and at the photon point, respectively, predictions for the timelike region of Dalitz decays $\mathrm{\Delta }\to N{e}^{+}{e}^{-}$ are presented.

We explore toponium, the smallest known quantum bound state of a top quark and its antiparticle, bound by the strong force. With a Bohr radius of $8\times {10}^{-18}\mathrm{m}$ and a lifetime of $2.5\times {10}^{-25}\mathrm{s}$, toponium uniquely probes microphysics. Unlike all other hadrons, it is governed by ultraviolet freedom. This distinction offers novel insights into quantum chromodynamics. Our analysis reveals a toponium signal exceeding $5\sigma$ in the distribution of the cross section ratio between $e^{+}{e}^{-}\to b\overline{b}$ and $e^{+}{e}^{-}\to q\overline{q}$ ($q=b$, $c$, $s$, $d$, $u$), based on $400{\mathrm{fb}}^{-1}$ of data collected at $\sqrt{s}\approx 341\mathrm{GeV}$. This discovery enables a top quark mass measurement with an uncertainty reduced by a factor of ten compared to current precision levels. Moreover, this method improves the systematic uncertainty by at least a factor of 2.7 compared to any other possible methods.

We discuss radiative transitions $D_{s1}\to D_s\gamma$ and $D_{s1}\to D_s^{*}\gamma$ of $p$-wave mesons. Since $D_{s1}$ mesons have no certain $C$-parity, and the masses of quarks in these mesons differ significantly, then due to the spin-orbit interaction, each of the $p$-wave mesons with the total angular momentum $J=1$ is a superposition of states with the total spin of quarks $S_{\mathrm{tot}}=0$ and $S_{\mathrm{tot}}=1$. We explain why the partial width of $D_{s1}(2460)\to D_s\gamma$ radiative transition is significantly larger than the corresponding value for $D_{s1}(2536)\to D_s\gamma$. We also predict the corresponding partial widths of $B_{s1}$ and $B_{c1}$.

We perform a systematical investigation of the doubly charmed dibaryon system with quantum numbers $IJ=01$ and strangeness numbers $S=0$, $-2$, and $-4$ in the framework of the chiral quark model. Two resonance states with strangeness numbers $S=-2$ are obtained in the $\mathrm{\Lambda }{\mathrm{\Omega }}_{cc}$ scattering channel: the ${\mathrm{\Xi }}_{cc}^{*}\mathrm{\Xi }$ state with resonance mass 5081 MeV and decay width 0.3 MeV, and the ${\mathrm{\Xi }}_c^{*}{\mathrm{\Xi }}_c^{\prime }$ state with mass 5213 MeV and decay width 19.8 MeV. These two predicted charmed dibaryon candidates are worth searching for experimentally. Besides this, we would like to emphasize that the multichannel coupling calculation is important for confirming the existence of multiquark states. The coupling can shift the energy of the resonance, give width to the resonance, and even destroy the resonance. Therefore, to provide the necessary information for experiments to search for exotic hadron states, the coupling calculation between the bound channels and open channels is indispensable.

We perform a numerical study of nonlocal partonic transport in anisotropic QCD matter, relevant to the evolution of hard probes in the aftermath of high-energy nuclear scattering events. The recently derived master equation, obtained from quantum field theory considerations, differs from Boltzmann transport by incorporating a nonlocal elastic scattering kernel arising from density gradients. After rewriting the master equation in a form suitable for numerical implementation and assuming a static density profile, we compare the nonlocal evolution to Boltzmann transport, demonstrating that the new interaction kernel is essential for accurately describing the azimuthal structure of the final-state momentum distribution. We further study the nonlocal partonic transport in the case of a matter profile governed by two-dimensional hydrodynamics, accounting for its flow and generalizing the evolution equation. Our results demonstrate the necessity of going beyond classical transport at high $p_t$ to accurately capture the structure of jets propagating through structured QCD matter. The master equation used in the numerical simulations can be seamlessly integrated into state-of-the-art transport codes.

We perform a detailed analysis of the semileptonic ${\mathrm{\Xi }}_b\to {\mathrm{\Xi }}_c{\ell }^{-}{\overline{\nu }}_{\ell }$ decays within the perturbative QCD framework. In our study, the ${\mathrm{\Xi }}_b\to {\mathrm{\Xi }}_c$ transition form factors are calculated using several popular models for baryonic light-cone distribution amplitudes. These form factors are then employed to analyze a range of observable quantities for the semileptonic processes via the helicity formalism. Our work presents predictions for the branching fractions of these decays for both the $\tau$ and $e$ channels. Notably, the obtained lepton flavor universality ratio, ${\mathcal{R}}_{{\mathrm{\Xi }}_c}\approx 0.3$, may offer new insights into the ${\mathcal{R}}^{(*)}$ puzzle. Furthermore, we investigate various angular observables, such as forward-backward asymmetries, lepton-side convexity parameters, and polarization asymmetries, which provide complementary information regarding potential new physics in $b$-baryonic semileptonic transitions. The numerical results for these angular observables are presented as both functions of $q^2$ and as averaged values. We observe that the lepton mass plays a significant role in shaping the angular distributions, affecting most of the observables under consideration. These results are expected to be valuable for both current and future experimental investigations of semileptonic heavy-to-heavy baryon decays.

Using $e^{+}{e}^{-}$ collision data corresponding to an integrated luminosity of $10.6{\mathrm{fb}}^{-1}$ collected at center-of-mass energies between 4.258 and 4.681 GeV with the BESIII detector at the BEPCII collider, we search for the $1^{-+}$ charmoniumlike hybrid via $e^{+}{e}^{-}\to \gamma \eta {\eta }_c$ and $e^{+}{e}^{-}\to \gamma {\eta }^{\prime }{\eta }_c$ decays for the first time. No significant signal is observed, and the upper limits on the Born cross sections for both processes are set at the 90% confidence level.

In this paper we continue our investigation of superstring scattering amplitudes in the conformal basis. We focus on the case of the four-graviton scattering processes at one loop in closed superstring theory. We write the expression for such a process in the celestial variables and confirm previous expectations. In particular, we find the adequate overall factorization of the ${\alpha }^{\prime }$ dependence which organizes the loop expansion of closed string celestial amplitudes. We also show that, at one loop, the field theory limit, when properly defined, commutes with the Mellin transform of the amplitudes for all values of the conformally invariant cross-ratio, something that had already been observed for gluon processes at one loop in open string theory and is to be compared with the tree-level computations. This indicates that many of the features satisfied for open string gluon amplitudes at tree and one-loop levels are also universal properties of graviton celestial amplitudes in closed string theory. As a by-product, we also compute field theory graviton amplitudes at one loop in the conformal basis.

Using the harmonic superspace approach, we perform a comprehensive study of the structure of divergences in the higher-derivative $6D$, $\mathcal{N}=(1,0)$ supersymmetric Yang-Mills theory coupled to the hypermultiplet in the adjoint representation. The effective action is constructed in the framework of the superfield background field method with the help of the $\mathcal{N}=(1,0)$ supersymmetric higher-derivative regularization scheme which preserves all symmetries of the theory. The one-loop divergences are calculated in a manifestly gauge invariant and $6D$, $\mathcal{N}=(1,0)$ supersymmetric form, hopefully admitting a generalization to higher loops. The $\beta$ function in the one-loop approximation is found and analyzed. In particular, it is shown that the one-loop $\beta$ function for an arbitrary regulator function is specified by integrals of double total derivatives in momentum space, like it happens in $4D$, $\mathcal{N}=1$ superfield gauge theories. This points to the potential possibility to derive the all-loop Novikov-Shifman-Vainshtein-Zakharov-like exact $\beta$ function in the considered theory.

We generalize the $\eta$ regularization scheme in order to develop a framework for systematically studying regularization of loops in quantum field theory. This allows us to“solve” a set of gauge consistency conditions for families of gauge invariant regularization schemes. We recover several known examples such as dimensional and denominator regularizations, as well as some more general solutions. We also study anomalies in chiral theories in order to carefully describe how our formalism should be properly implemented.

We present a modification to a “rotating” version of the dynamical Alcubierre spacetime, which was previously shown to permit closed timelike curves (CTCs). We find that if the effective rotation rate is made dependent on the spacetime coordinates within the bubble, a class of closed timelike curves are promoted to spatially circular geodesics. These paths provide a simple model of a free particle interacting with a CTC for a finite proper time interval, entering and exiting in flat spacetime. Despite the questionable physical realisability of our metric, we suggest that it may provide a useful background for future theoretical studies of classical and quantum models of time travel in a general relativistic setting.

Einstein-aether gravity is a theory that breaks the local Lorentz symmetry by introducing a preferred direction via a vector field, which is considered to play the role of an aether. The theory is identified by four coupling constants between the aether and gravity. Minimal Einstein-aether is the special case in which only one of the couplings is non-zero. We show that the aether vector field in its minimal version is Hodge dual to a gauge field. The gauge symmetry in the dual description has been known for decades and has been used to implement a cosmological constant into the Lagrangian. As a result, solutions to the well-established gauge theory can be transferred into the minimal Einstein-aether theory straightforwardly. On the other hand, some of the proposed solutions to the minimal Einstein-aether theory could be discarded as pure gauges of the vanishing aether. We prove as a theorem that this holds true for all divergenceless aether fields.

For locally rotationally symmetric (LRS) spacetimes, we construct two equivalent forms of the Komar current derived from a conformal Killing vector. One is a kinematic construction and the other is in terms of the matter quantities on the spacetime. The required conservation condition for the current is derived and discussed in various instances, and the implications of the conservation of the current, and in the case of a vanishing current, are analyzed. A relationship between the conservation criterion and the presence of trapped surfaces in the spacetime is found and discussed. We also show that for LRS II metrics with a constant metric time component, the current is always conserved. In the presence of a conformal Killing horizon, properties of the current are analyzed, and restrictions on and some implications for the physical spacetime variables in the vicinity of the horizon are obtained. Finally, with respect to the conformal Killing horizon, the associated Noether charge is shown to be proportional to the surface gravity, establishing the thermodynamic interpretation of the Noether charge.

In Remmen and Carroll 2013, it was claimed that in the spatially flat cosmological case there exists a unique conserved measure (up to normalization) on the $(\varphi ,\dot{\varphi })$ phase space for scalar field with $m^2{\varphi }^2$ potential by finding a unique solution to the differential equation (44) (in Remmen and Carroll 2013) in the low-energy regime. In Remmen and Carroll 2014, it was also claimed that a unique solution to the same differential equation was found in the high-energy regime and using this solution the authors calculated the expected total number of $e$-folds of inflation. In this comment, we reanalyze the differential equation (44) and obtain general solutions both in the low-energy and high-energy regime, which can include the solution in Remmen and Carroll 2013 and the solution in Remmen and Carroll 2014 as a special case in the corresponding energy regime. In this way, we find that following the constructions in the 2013 article there actually exist infinitely many nonequivalent conserved measures for the scalar-field cosmology with $m^2{\varphi }^2$ potential on the $(\varphi ,\dot{\varphi })$ phase space. Moreover, through specific calculations, we also show that different choices of measures can lead to quite different predictions of the expected total number of $e$-folds of inflation.