The redshifted 21-cm line of hydrogen holds great potential for the study of cosmology, as it can probe otherwise unobservable cosmic epochs. In particular, measurements of the 21-cm power spectrum during cosmic dawn—the era when the first stars were formed—will provide us with a wealth of information about the astrophysics of stellar formation, as well as the origin of fluctuations intn our Universe. In addition to their usually considered density fluctuations, dark matter and baryons possess large relative velocities with respect to each other, due to the baryon acoustic oscillations suffered by the latter, which suppress the formation of stars during cosmic dawn, leaving an imprint on 21-cm observables during this era. Here we present 21cmvfast, a version of the publicly available code 21cmvfast modified to account for this effect. Previous work has shown that the inclusion of relative velocities produces an acoustic modulation on the large-scale 21-cm power spectrum during cosmic dawn. By comparing analytic calculations with simulations from 21cmvfast, here we demonstrate that this modulation takes the form of robust velocity-induced acoustic oscillations (VAOs), during both the Lyman-$\alpha$ coupling era and the subsequent epoch of heating. The unique shape of these VAOs, which is determined by the acoustic physics that generated the relative velocities, can be analytically computed and is easily distinguishable from the usual density-sourced fluctuations. We find that, under a broad range of astrophysical assumptions, the VAOs are detectable at high significance by the upcoming HERA interferometer, which could therefore confirm the presence of acoustic oscillations at cosmic dawn.

The dipion transitions $\mathrm{\Upsilon }(2S,3S,4S)\to \mathrm{\Upsilon }(1S,2S)\pi \pi$ are systematically studied by considering the mechanisms of the hadronization of soft gluons, exchanging the bottomoniumlike $Z_b$ states, and the bottom-meson loops. The strong pion-pion final-state interaction, especially including the channel coupling to $K\overline{K}$ in the $S$-wave, is taken into account in a model-independent way using the dispersion theory. Through fitting to the available experimental data, we extract values of the transition chromopolarizabilities $|{\alpha }_{\mathrm{\Upsilon }(mS)\mathrm{\Upsilon }(nS)}|$, which measure the chromoelectric couplings of the bottomonia with soft gluons. It is found that the $Z_b$ exchange has a slight impact on the extracted chromopolarizablity values, and the obtained $|{\alpha }_{\mathrm{\Upsilon }(2S)\mathrm{\Upsilon }(1S)}|$ considering the $Z_b$ exchange is $(0.29\pm 0.20){\mathrm{GeV}}^{-3}$. Our results could be useful in studying the interactions of bottomonium with light hadrons.

We explore the large spin spectrum in two-dimensional conformal field theories with a finite twist gap, using the modular bootstrap in the light-cone limit. By recursively solving the modular crossing equations associated with different $PSL(2,\mathbb{Z})$ elements, we identify the universal contribution to the density of large spin states from the vacuum in the dual channel. Our result takes the form of a sum over $PSL(2,\mathbb{Z})$ elements, whose leading term generalizes the usual Cardy formula to a wider regime. Rather curiously, the contribution to the density of states from the vacuum becomes negative in a specific limit, which can be canceled by that from a nonvacuum Virasoro primary whose twist is no bigger than $\frac{c-1}{16}$. This suggests a new upper bound of $\frac{c-1}{16}$ on the twist gap in any $c>1$ compact, unitary conformal field theory with a vacuum, which would in particular imply that pure ${\mathrm{AdS}}_3$ gravity does not exist. We confirm this negative density of states in the pure gravity partition function by Maloney, Witten, and Keller. We generalize our discussion to theories with $\mathcal{N}=(1,1)$ supersymmetry and find similar results.

In this paper we study the two-body gravitational scattering of massive scalars with different masses in general spacetime dimensions. We focus on the Regge limit (eikonal regime) of the resulting scattering amplitudes and discuss how to extract the classical information representing the scattering of two black holes. We derive the leading eikonal and explicitly show the resummation of the first leading energy contribution up to second order in Newton’s gravitational constant. We also calculate the subleading eikonal showing that in general spacetime dimensions it receives a nontrivial contribution from the box integral. From the eikonal we extract the two-body classical scattering angle between the two black holes up to the second post-Minkowskian order. Taking various probe-limits of the two-body scattering angles we are able to show agreement between our results and various results in the literature. We highlight that the box integral also has a log-divergent (in energy) contribution at subsubleading order which violates perturbative unitarity in the ultrarelativistic limit. We expect this term to play a role in the calculation of the eikonal at the third post-Minkowskian order.

We present a theoretical analysis of an electron confined by a Penning trap, also known as geonium, that is affected by gravity. In particular, we investigate the gravitational influence on the electron dynamics and the electromagnetic field of the trap. We consider the special case of a homogeneous gravitational field, which is represented by Rindler spacetime. In this spacetime the Hamiltonian of an electron with anomalous magnetic moment is constructed. Based on this Hamiltonian and the exact solution to Maxwell equations for the field of a Penning trap in Rindler spacetime, we derive the transition energies of geonium up to the relativistic corrections of $1/{\mathrm{c}}^2$. These transition energies are used to obtain an extension of the well known ${\mathrm{g}}_s$-factor formula introduced by L. S. Brown and G. Gabrielse [Rev. Mod. Phys. 58, 233 1986].

Completeness of the spectrum of charged branes in a quantum theory of gravity naturally motivates the question of whether the consistency of what lives on the branes can be used to explain some of the swampland conditions. In this paper, we focus on consistency of what lives on string probes to show that some of the theories with $\mathcal{N}=(1,0)$ supersymmetry in ten dimensions and six dimensions, which are otherwise consistent looking, belong to the swampland. Gravitational and gauge group anomaly inflow on these probes can be used to compute the gravitational central charges $(c_L,c_R)$ as well as the level of the group’s current algebra $k_L$. The fact that the left-moving central charge on the string probes should be large enough to allow unitary representations of the current algebra with a given level can be used to rule out some theories. This, in particular, explains why it has not been possible to construct the corresponding theories from string theory.

In this paper, we verify the large scale structure consistency relations using $N$-body simulations, including modes in the highly nonlinear regime. These relations (pointed out by Kehagias & Riotto and Peloso & Pietroni) follow from the symmetry of the dynamics under a shift of the Newtonian potential by a constant and a linear gradient, and predict the absence of certain poles in the ratio between the (equal time) squeezed bispectrum and power spectrum. The consistency relations, as symmetry statements, are exact, but have not been previously checked beyond the perturbative regime. Our test using $N$-body simulations not only offers a nonperturbative check, but also serves as a warm-up exercise for applications to observational data. A number of subtleties arise when taking the squeezed limit of the bispectrum—we show how to circumvent or address them. An interesting by-product of our investigation is an explicit demonstration that the linear-gradient symmetry is unaffected by the periodic boundary condition of the simulations. Lastly, we verify using simulations that the consistency relations are violated when the initial conditions are non-Gaussian (of the local $f_{\mathrm{NL}}$ type). The methodology developed here paves the way for constraining primordial non-Gaussianity using large scale structure data, including (numerous) highly nonlinear modes that are otherwise hard to interpret and utilize.

The leading electromagnetic (e.m.) and strong isospin-breaking corrections to the ${\pi }^{+}\to {\mu }^{+}\nu [\gamma ]$ and $K^{+}\to {\mu }^{+}\nu [\gamma ]$ leptonic decay rates are evaluated for the first time on the lattice. The results are obtained using gauge ensembles produced by the European Twisted Mass Collaboration with $N_f=2+1+1$ dynamical quarks. The relative leading-order e.m. and strong isospin-breaking corrections to the decay rates are 1.53(19)% for ${\pi }_{\mu 2}$ decays and 0.24(10)% for $K_{\mu 2}$ decays. Using the experimental values of the ${\pi }_{\mu 2}$ and $K_{\mu 2}$ decay rates and updated lattice QCD results for the pion and kaon decay constants in isosymmetric QCD, we find that the Cabibbo-Kobayashi-Maskawa matrix element $|V_{us}|=0.22538(46)$, reducing by a factor of about 1.8 the corresponding uncertainty in the particle data group review. Our calculation of $|V_{us}|$ allows also an accurate determination of the first-row Cabibbo-Kobayashi-Maskawa unitarity relation $|V_{ud}{|}^2+|V_{us}{|}^2+|V_{ub}{|}^2=0.99988(46)$. Theoretical developments in this paper include a detailed discussion of how QCD can be defined in the full $\mathrm{QCD}+\mathrm{QED}$ theory and an improved renormalization procedure in which the bare lattice operators are renormalized nonperturbatively into the regularization independent momentum subtraction (RI’-MOM) scheme and subsequently matched perturbatively at $O({\alpha }_{\mathrm{em}}{\alpha }_s(M_W))$ into the W-regularization scheme appropriate for these calculations.

We study the accuracy and predictive power of conformal perturbation theory by a comparison with lattice results in the neighborhood of the finite-temperature deconfinement transition of SU(2) Yang-Mills theory, assuming that the infrared properties of this non-Abelian gauge theory near criticality can be described by the Ising model. The results of this comparison show that conformal perturbation theory yields quantitatively accurate predictions in a broad temperature range. We discuss the implications of these findings for the description of the critical point (belonging to the same universality class) of another strongly coupled, nonsupersymmetric non-Abelian gauge theory: the critical end point in the phase diagram of QCD at finite temperature and finite quark chemical potential.

In this paper, we test the perturbative halo bias model at the field level. The advantage of this approach is that any analysis can be done without sample variance if the same initial conditions are used in simulations and perturbation theory calculations. We write the bias expansion in terms of modified bias operators in Eulerian space, designed such that the large bulk flows are automatically resummed and not treated perturbatively. Using these operators, the bias model accurately matches the Eulerian density of halos in N-body simulations. The mean-square model error is close to the Poisson shot noise for a wide range of halo masses, and it is rather scale independent, with scale-dependent corrections becoming relevant at the nonlinear scale. In contrast, for the linear bias, the mean-square model error can be higher than the Poisson prediction by factors of up to a few on large scales, and it becomes scale dependent already in the linear regime. We show that by weighting simulated halos by their mass, the mean-square error of the model can be further reduced by up to an order of magnitude, or by a factor of 2 when including 60% mass scatter. We also test the standard Eulerian bias model using the nonlinear matter field measured from simulations and show that it leads to a larger and more scale-dependent model error than the bias expansion based on perturbation theory. These results may be of particular relevance for cosmological inference methods that use a likelihood of the biased tracer at the field level or for initial condition and baryon acoustic oscillation reconstruction that requires a precise estimate of the large-scale potential from the biased tracer density.

We report measurements of the lifetimes of the ${\mathrm{\Lambda }}_c^{+}$, ${\mathrm{\Xi }}_c^{+}$ and ${\mathrm{\Xi }}_c^0$ charm baryons using proton-proton collision data at center-of-mass energies of 7 and 8 TeV, corresponding to an integrated luminosity of $3.0{\mathrm{fb}}^{-1}$, collected by the LHCb experiment. The charm baryons are reconstructed through the decays ${\mathrm{\Lambda }}_c^{+}\to p{K}^{-}{\pi }^{+}$, ${\mathrm{\Xi }}_c^{+}\to p{K}^{-}{\pi }^{+}$ and ${\mathrm{\Xi }}_c^0\to p{K}^{-}{K}^{-}{\pi }^{+}$, and originate from semimuonic decays of beauty baryons. The lifetimes are measured relative to that of the $D^{+}$ meson, and are determined to be ${\tau }_{{\mathrm{\Lambda }}_c^{+}}=203.5\pm 1.0\pm 1.3\pm 1.4\mathrm{fs},{\tau }_{{\mathrm{\Xi }}_c^{+}}=456.8\pm 3.5\pm 2.9\pm 3.1\mathrm{fs},{\tau }_{{\mathrm{\Xi }}_c^0}=154.5\pm 1.7\pm 1.6\pm 1.0\mathrm{fs},$ where the uncertainties are statistical, systematic, and due to the uncertainty in the $D^{+}$ lifetime. The measurements are approximately 3–4 times more precise than the current world average values. The ${\mathrm{\Lambda }}_c^{+}$ and ${\mathrm{\Xi }}_c^{+}$ lifetimes are in agreement with previous measurements; however, the ${\mathrm{\Xi }}_c^0$ baryon lifetime is approximately 3.3 standard deviations larger than the world average value.

We point out two ways to search for low-mass axion dark matter using cosmic microwave background (CMB) polarization measurements. These appear, in particular, to be some of the most promising ways to directly detect fuzzy dark matter. Axion dark matter causes rotation of the polarization of light passing through it. This gives rise to two novel phenomena in the CMB. First, the late-time oscillations of the axion field today cause the CMB polarization to oscillate in phase across the entire sky. Second, the early-time oscillations of the axion field wash out the polarization produced at last scattering, reducing the polarized fraction (TE and EE power spectra) compared to the standard prediction. Since the axion field is oscillating, the common (static) “cosmic birefringence” search is not appropriate for axion dark matter. These two phenomena can be used to search for axion dark matter at the lighter end of the mass range, with a reach several orders of magnitude beyond current constraints. We set a limit from the washout effect using existing Planck results, and find significant future discovery potential for CMB detectors searching in particular for the oscillating effect.

The recent detection of gravitational waves (GWs) from the neutron star binary inspiral GW170817 has opened a unique avenue to probe matter and fundamental interactions in previously unexplored regimes. Extracting information on neutron star matter from the observed GWs requires robust and computationally efficient theoretical waveform models. We develop an approximate frequency-domain GW phase model of a main GW signature of matter: dynamic tides associated with the neutron stars’ fundamental oscillation modes ($f$-modes). We focus on nonspinning objects on circular orbits and demonstrate that, despite its mathematical simplicity, the new “$f$-mode tidal” (fmtidal) model is in good agreement with the effective-one-body dynamical tides model up to GW frequencies of $\gtrsim 1\mathrm{kHz}$ and gives physical meaning to part of the phenomenology captured in tidal models tuned to numerical relativity. The advantages of the fmtidal model are that it makes explicit the dependence of the GW phasing on the characteristic equation-of-state parameters, i.e., tidal deformabilities and $f$-mode frequencies; it is computationally efficient; and it can readily be added to any frequency-domain baseline waveform. The fmtidal model is easily amenable to future improvements and provides the means for a first step towards independently measuring additional fundamental properties of neutron star matter beyond the tidal deformability as well as performing novel tests of general relativity from GW observations.

We report a new binary black hole merger in the publicly available LIGO first observing run (O1) data release. The event has a false alarm rate of one per six years in the detector-frame chirp-mass range ${\mathcal{M}}^{\det }\in [20,40]M_{\odot }$ in a new independent analysis pipeline that we developed. Our best estimate of the probability that the event is of astrophysical origin is $P_{\text{astro}}\sim 0.71$. The estimated physical parameters of the event indicate that it is the merger of two massive black holes, ${\mathcal{M}}^{\det }=31_{-3}^{+2}{M}_{\odot }$ with an effective spin parameter, ${\chi }_{\mathrm{eff}}=0.81_{-0.21}^{+0.15}$, making this the most highly spinning merger reported to date. It is also among the two highest redshift mergers observed so far. The high aligned spin of the merger supports the hypothesis that merging binary black holes can be created by binary stellar evolution.

The energy-energy-correlator (EEC) observable in $e^{+}{e}^{-}$ annihilation measures the energy deposited in two detectors as a function of the angle between the detectors. The collinear limit, where the angle between the two detectors approaches zero, is of particular interest for describing the substructure of jets produced at hadron colliders as well as in $e^{+}{e}^{-}$ annihilation. We derive a factorization formula for the leading power asymptotic behavior in the collinear limit of a generic quantum field theory, which allows for the resummation of logarithmically enhanced terms to all orders by renormalization group evolution. The relevant anomalous dimensions are expressed in terms of the timelike data of the theory, in particular the moments of the timelike splitting functions, which are known to high perturbative orders. We relate the small angle and back-to-back limits to each other via the total cross section and an integral over intermediate angles. This relation, for the EEC in $e^{+}{e}^{-}$ and in Higgs decay to gluons, provides us with the initial conditions for quark and gluon jet functions at order ${\alpha }_s^2$. In QCD and in $\mathcal{N}=1$ super-Yang-Mills theory, we then perform the resummation to next-to-next-to-leading logarithm, improving previous calculations by two perturbative orders. We highlight the important role played by the nonvanishing $\beta$ function in these theories, which while subdominant for Higgs decays to gluons, dominates the behavior of the EEC in the collinear limit for $e^{+}{e}^{-}$ annihilation, and in $\mathcal{N}=1$ super-Yang-Mills theory. In conformally invariant $\mathcal{N}=4$ super-Yang-Mills theory, reciprocity between timelike and spacelike evolution can be used to express our factorization formula as a power law with exponent equal to the spacelike twist-two spin-three anomalous dimensions, thus providing a connection between timelike and spacelike approaches.

In relativistic kinetic theory, the one-particle distribution function is approximated by an asymptotic perturbative power series in the Knudsen number which is divergent. For the Bjorken flow, we expand the distribution function in terms of its moments and study their nonlinear evolution equations. The resulting coupled dynamical system can be solved for each moment consistently using a multiparameter transseries which makes the constitutive relations inherit the same structure. A new nonperturbative dynamical renormalization scheme is born out of this formalism that goes beyond the linear response theory. We show that there is a Lyapunov function, also known as dynamical potential, which is, in general, a function of the moments and time satisfying Lyapunov stability conditions along renormalization group flows connected to the asymptotic hydrodynamic fixed point. As a result, the transport coefficients get dynamically renormalized at every order in the time-dependent perturbative expansion by receiving nonperturbative corrections present in the transseries. The connection between the integration constants and the UV data is discussed using the language of dynamical systems. Furthermore, we show that the first dissipative correction in the Knudsen number to the distribution function is not only determined by the known effective shear viscous term but also a new high-energy nonhydrodynamic mode. It is demonstrated that the survival of this new mode is intrinsically related to the nonlinear mode-to-mode coupling with the shear viscous term. Finally, we comment on some possible phenomenological applications of the proposed nonhydrodynamic transport theory.

Dark matter (DM) could couple to particles in the Standard Model (SM) through a light vector mediator. In the limit of small coupling, this portal could be responsible for producing the observed DM abundance through a mechanism known as freeze-in. Furthermore, the requisite DM-SM couplings provide a concrete benchmark for direct and indirect searches for DM. We present updated calculations of the relic abundance for DM produced by freeze-in through a light vector mediator. We identify an additional production channel: the decay of photons that acquire an in-medium plasma mass. These plasmon decays are a dominant channel for DM production for sub-MeV DM masses, and including this channel leads to a significant reduction in the predicted signal strength for DM searches. Accounting for production from both plasmon decays and annihilations of SM fermions, the DM acquires a highly nonthermal phase-space distribution which impacts the cosmology at later times; these cosmological effects will be explored in a companion paper.

Studies of on-shell and off-shell Higgs boson production in the four-lepton final state are presented, using data from the CMS experiment at the LHC that correspond to an integrated luminosity of $80.2{\mathrm{fb}}^{-1}$ at a center-of-mass energy of 13 TeV. Joint constraints are set on the Higgs boson total width and parameters that express its anomalous couplings to two electroweak vector bosons. These results are combined with those obtained from the data collected at center-of-mass energies of 7 and 8 TeV, corresponding to integrated luminosities of 5.1 and $19.7{\mathrm{fb}}^{-1}$, respectively. Kinematic information from the decay particles and the associated jets are combined using matrix element techniques to identify the production mechanism and to increase sensitivity to the Higgs boson couplings in both production and decay. The constraints on anomalous $HVV$ couplings are found to be consistent with the standard model expectation in both the on-shell and off-shell regions. Under the assumption of a coupling structure similar to that in the standard model, the Higgs boson width is constrained to be $3.2_{-2.2}^{+2.8}\mathrm{MeV}$ while the expected constraint based on simulation is $4.1_{-4.0}^{+5.0}\mathrm{MeV}$. The constraints on the width remain similar with the inclusion of the tested anomalous $HVV$ interactions.

We investigate the asymptotic structure of electromagnetism in Minkowski space in even and odd spacetime dimensions $\ge 4$. We focus on $d>4$ since the case $d=4$ has been studied previously at length. We first consider spatial infinity where we provide explicit boundary conditions that admit the known physical solutions and make the formalism well defined (finite symplectic structure and charges). Contrary to the situation found in $d=4$ dimensions, there is no need to impose parity conditions under the antipodal map on the leading order of the fields when $d>4$. There is, however, the same need to modify the standard bulk symplectic form by a boundary term at infinity involving a surface degree of freedom. This step makes the Lorentz boosts act canonically. Because of the absence of parity conditions, the theory is found to be invariant under two independent algebras of angle-dependent $u(1)$ transformations ($d>4$). We then integrate the equations of motion in order to find the behavior of the fields near null infinity. We exhibit the radiative and Coulomb branches, characterized by different decays and parities. The analysis yields generalized matching conditions between the past of ${\mathcal{I}}^{+}$ and the future of ${\mathcal{I}}^{-}$.

We propose using high-purity lab-grown diamond crystal for the detection of sub–giga electron volt dark matter. Diamond targets can be sensitive to both nuclear and electron recoils from dark matter scattering in the mega-electron-volt and above mass range as well as to absorption processes of dark matter with masses between sub–electron volts to tens of electron volts. Compared to other proposed semiconducting targets such as germanium and silicon, diamond detectors can probe lower dark matter masses via nuclear recoils due to the lightness of the carbon nucleus. The expected reach for electron recoils is comparable to that of germanium and silicon, with the advantage that dark counts are expected to be under better control. Via absorption processes, unconstrained QCD axion parameter space can be successfully probed in diamond for masses of order 10 eV, further demonstrating the power of our approach.