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.

We study the cosmological effects of two-body dark matter decays in which the products of the decay include a massless and a massive particle. We show that if the massive daughter particle is slightly warm it is possible to relieve the tension between distance ladder measurements of the present-day Hubble parameter with measurements from the cosmic microwave background.

Perturbative expansions, such as the well-known gradient series and the recently proposed slow-roll expansion, have been recently used to investigate the emergence of hydrodynamic behavior in systems undergoing Bjorken flow. In this paper we determine for the first time the large order behavior of these perturbative expansions in relativistic hydrodynamics in the case of Gubser flow. While both series diverge, the slow-roll series can provide a much better overall description of the system’s dynamics than the gradient expansion when both series are truncated at low orders. The truncated slow-roll series can also describe the attractor solution of Gubser flow as long as the system is sufficiently close to equilibrium near the origin (i.e., $\rho =0$) in $d{S}_3\otimes \mathbb{R}$. Differently than the case of Bjorken flow, here we show that the Gubser flow attractor solution is not solely a function of the effective Knudsen number ${\tau }_R\sqrt{{\sigma }_{\mu \nu }{\sigma }^{\mu \nu }}\sim {\tau }_R\tanh \rho$. Our results give further support to the idea that new resummed constitutive relations between dissipative currents and the gradients of conserved quantities can emerge in systems far from equilibrium that are beyond the regime of validity of the usual gradient expansion.

We present constraints on extensions of the minimal cosmological models dominated by dark matter and dark energy, $\mathrm{\Lambda }\mathrm{CDM}$ and $w\mathrm{CDM}$, by using a combined analysis of galaxy clustering and weak gravitational lensing from the first-year data of the Dark Energy Survey (DES Y1) in combination with external data. We consider four extensions of the minimal dark energy-dominated scenarios: (1) nonzero curvature ${\mathrm{\Omega }}_k$, (2) number of relativistic species $N_{\mathrm{eff}}$ different from the standard value of 3.046, (3) time-varying equation-of-state of dark energy described by the parameters $w_0$ and $w_a$ (alternatively quoted by the values at the pivot redshift, $w_p$, and $w_a$), and (4) modified gravity described by the parameters ${\mu }_0$ and ${\mathrm{\Sigma }}_0$ that modify the metric potentials. We also consider external information from Planck cosmic microwave background measurements; baryon acoustic oscillation measurements from SDSS, 6dF, and BOSS; redshift-space distortion measurements from BOSS; and type Ia supernova information from the Pantheon compilation of datasets. Constraints on curvature and the number of relativistic species are dominated by the external data; when these are combined with DES Y1, we find ${\mathrm{\Omega }}_k=0.0020_{-0.0032}^{+0.0037}$ at the 68% confidence level, and the upper limit $N_{\mathrm{eff}}<3.28(3.55)$ at 68% (95%) confidence, assuming a hard prior $N_{\mathrm{eff}}>3.0$. For the time-varying equation-of-state, we find the pivot value $(w_p,w_a)=(-0.91_{-0.23}^{+0.19},-0.57_{-1.11}^{+0.93})$ at pivot redshift $z_p=0.27$ from DES alone, and $(w_p,w_a)=(-1.01_{-0.04}^{+0.04},-0.28_{-0.48}^{+0.37})$ at $z_p=0.20$ from DES Y1 combined with external data; in either case we find no evidence for the temporal variation of the equation of state. For modified gravity, we find the present-day value of the relevant parameters to be ${\mathrm{\Sigma }}_0=0.43_{-0.29}^{+0.28}$ from DES Y1 alone, and $({\mathrm{\Sigma }}_0,{\mu }_0)=(0.06_{-0.07}^{+0.08},-0.11_{-0.46}^{+0.42})$ from DES Y1 combined with external data. These modified-gravity constraints are consistent with predictions from general relativity.

We discuss some implications of the recently suggested swampland conjecture $\frac{|\nabla V|}{V}\gtrsim c\sim 1$, together with a previous one $\mathrm{\Delta }\varphi \lesssim 1$. We list some implications for particle phenomenology and the early Universe. The most intriguing implication of the conjecture could be a significant shift in allowed inflationary models, if not ruling out slow-roll (single field) inflation altogether. The tension of inflation and the conjecture does not only regard the amplitude of the tensor spectrum, but also its tilt, as $c\gtrsim 1$ implies both a yet unobserved tensor to scalar ratio, and an enhancement of the observed scalar power spectrum on large scales in discord with current data that favors a suppression on these scales. Scalar fields are abundant in theories of quantum gravity. Considering a second scalar field, its dynamics are dictated by the relation between its mass, $m$, and the Hubble parameter, $H$, at different epochs in the history of the Universe. This scalar field, a drainon, fulfills the conjecture draining up the swampland. For inflation, this drainon requires a modest hierarchy compared to the inflaton. For the rest of the thermal history of the Universe, the drainon can be a coherently oscillating scalar field strengthening the case of dark matter candidates of that sort.

Force-free electrodynamics (FFE) is a closed set of equations for the electromagnetic field of a magnetically dominated plasma. There are strong arguments for the existence of force-free plasmas near pulsars and active black holes, but FFE alone cannot account for the observational signatures, such as coherent radio emission and relativistic jets and winds. We reformulate FFE as the effective field theory of a cold string fluid and initiate a systematic study of corrections in a derivative expansion. At leading order the effective theory is equivalent to (generalized) FFE, with the strings comprised by magnetic field line world sheets. Higher-order corrections generically give rise to nonzero accelerating electric fields ($\mathbf{E}·\mathbf{B}\ne 0$). We discuss potential observable consequences and comment on an intriguing numerical coincidence.