Predictions of glueball decay rates in the holographic Witten-Sakai-Sugimoto model for low-energy QCD can be uniquely extended to include finite quark masses up to an as-yet-undetermined parameter in the coupling of glueballs to the nonanomalous part of the pseudoscalar mass terms. The assumption of a universal coupling of glueballs to mass terms of the full nonet of pseudoscalar mesons leads to flavor asymmetries in the decay rates of scalar glueballs that agree well with experimental data for the glueball candidate $f_0(1710)$ and implies a vanishing decay rate into $\eta {\eta }^{\prime }$ pairs, for which only upper bounds for the $f_0(1710)$ meson are known at present from experiment. Relaxing this assumption, the holographic model gives a tight correlation between the decay rates into pairs of pseudo-Goldstone bosons of the same type and $\eta {\eta }^{\prime }$ pairs. If $\mathrm{\Gamma }(G\to KK)/\mathrm{\Gamma }(G\to \pi \pi )$ is kept within the range reported currently by the Particle Data Group for the $f_0(1710)$ meson, the rate $\mathrm{\Gamma }(G\to \eta {\eta }^{\prime })/\mathrm{\Gamma }(G\to \pi \pi )$ is predicted to be $\lesssim 0.04$. The corresponding situation for $f_0(1500)$ is also discussed; however, this is found to be much less compatible with the interpretation of a largely unmixed glueball.

Nucleon-nucleon systems are studied with lattice quantum chromodynamics at a pion mass of $m_{\pi }\sim 450\mathrm{MeV}$ in three spatial volumes using $n_f=2+1$ flavors of light quarks. At the quark masses employed in this work, the deuteron binding energy is calculated to be $B_d=14.4_{-2.6}^{+3.2}\mathrm{MeV}$, while the dineutron is bound by $B_{nn}=12.5_{-5.0}^{+3.0}\mathrm{MeV}$. Over the range of energies that are studied, the S-wave scattering phase shifts calculated in the ${}^1{S}_0$ and ${{}^{3}S}_1-{{}^{3}D}_1$ channels are found to be similar to those in nature, and indicate repulsive short-range components of the interactions, consistent with phenomenological nucleon-nucleon interactions. In both channels, the phase shifts are determined at three energies that lie within the radius of convergence of the expansion, allowing for constraints to be placed on the inverse scattering lengths and effective ranges. The extracted phase shifts allow for matching to nuclear effective field theories, from which low-energy counterterms are extracted and issues of convergence are investigated. As part of the analysis, a detailed investigation of the single hadron sector is performed, enabling a precise determination of the violation of the Gell-Mann–Okubo mass relation.

We carry out numerical experiments in the critical collapse of a spherically symmetric massless scalar field in $2+1$ spacetime dimensions in the presence of a negative cosmological constant and compare them against a new theoretical model. We approximate the true critical solution as the $n=4$ Garfinkle solution, matched at the light cone to a Vaidya-like solution, and corrected to leading order for the effect of $\mathrm{\Lambda }<0$. This approximation is only $C^3$ at the light cone and has three growing modes. We conjecture that pointwise it is a good approximation to a yet unknown true critical solution that is analytic with only one growing mode (itself approximated by the top mode of our amended Garfinkle solution). With this conjecture, we predict a Ricci-scaling exponent of $\gamma =8/7$ and a mass-scaling exponent of $\delta =16/23$, compatible with our numerical experiments.

Ab initio numerical simulations of the thermodynamics of dense quark matter remain a challenge. Apart from the infamous sign problem, lattice methods have to deal with finite volume and discretization effects as well as with the necessity to introduce sources for symmetry-breaking order parameters. We study these artifacts in the Polyakov-loop-extended Nambu–Jona-Lasinio (PNJL) model and compare its predictions to existing lattice data for cold and dense two-color matter with two flavors of Wilson quarks. To achieve even qualitative agreement with lattice data requires the introduction of two novel elements in the model: (i) explicit chiral symmetry breaking in the effective contact four-fermion interaction, referred to as the chiral twist, and (ii) renormalization of the Polyakov loop. The feedback of the dense medium to the gauge sector is modeled by a chemical-potential-dependent scale in the Polyakov-loop potential. In contrast to previously used analytical Ansätze, we determine its dependence on the chemical potential from lattice data for the expectation value of the Polyakov loop. Finally, we propose adding a two-derivative operator to our effective model. This term acts as an additional source of explicit chiral symmetry breaking, mimicking an analogous term in the lattice Wilson action.

We constrain anisotropic cosmic birefringence using four-point correlations of even-parity $E$-mode and odd-parity $B$-mode polarization in the cosmic microwave background measurements made by the POLARization of the Background Radiation (POLARBEAR) experiment in its first season of observations. We find that the anisotropic cosmic birefringence signal from any parity-violating processes is consistent with zero. The Faraday rotation from anisotropic cosmic birefringence can be compared with the equivalent quantity generated by primordial magnetic fields if they existed. The POLARBEAR nondetection translates into a 95% confidence level (C.L.) upper limit of 93 nanogauss (nG) on the amplitude of an equivalent primordial magnetic field inclusive of systematic uncertainties. This four-point correlation constraint on Faraday rotation is about 15 times tighter than the upper limit of 1380 nG inferred from constraining the contribution of Faraday rotation to two-point correlations of $B$-modes measured by Planck in 2015. Metric perturbations sourced by primordial magnetic fields would also contribute to the $B$-mode power spectrum. Using the POLARBEAR measurements of the $B$-mode power spectrum (two-point correlation), we set a 95% C.L. upper limit of 3.9 nG on primordial magnetic fields assuming a flat prior on the field amplitude. This limit is comparable to what was found in the Planck 2015 two-point correlation analysis with both temperature and polarization. We perform a set of systematic error tests and find no evidence for contamination. This work marks the first time that anisotropic cosmic birefringence or primordial magnetic fields have been constrained from the ground at subdegree scales.

We calculate the massive Wilson coefficients for the heavy-flavor contributions to the nonsinglet charged-current deep-inelastic scattering structure function $x{F}_3^{W^{+}}(x,Q^2)+x{F}_3^{W^{-}}(x,Q^2)$ in the asymptotic region $Q^2\gg m^2$ to three-loop order in QCD at general values of the Mellin variable $N$ and the momentum fraction $x$. Besides the heavy-quark pair production also the single heavy-flavor excitation $s\to c$ contributes. Numerical results are presented for the charm-quark contributions and consequences on the Gross-Llewellyn Smith sum rule are discussed.

There are very few direct experimental tests of the inverse square law of gravity at distances comparable to the scale of the Solar System and beyond. Here we describe a possible space mission optimized to test the inverse square law at a scale of up to 100 AU. For example, sensitivity to a Yukawa correction with a strength of $10^{-7}$ times gravity and length scale of 100 AU is within reach, improving the current state of the art by over two orders of magnitude. This experiment would extend our understanding of gravity to the largest scale that can be reached with a direct probe using known technology. This would provide a powerful test of long-distance modifications of gravity including many theories motivated by dark matter or dark energy.

We revisit Heisenberg’s model for nucleon-nucleon scattering which admits a saturation of the Froissart bound. We examine its uniqueness, and find that up to certain natural generalizations, it is the only action that saturates the bound. We find that we can extract also subleading behavior for ${\sigma }_{\mathrm{tot}}(s)$ from it, though that requires a knowledge of the wave function solution that is hard to obtain, and a black-disk model allows the calculation of ${\sigma }_{\text{elastic}}(s)$ as well. The wave-function solution is analyzed perturbatively, and its source is interpreted. Generalizations to several mesons, the addition of vector mesons, and curved space regimes are also found. We discuss the relations between Heisenberg’s model and holographic models that are dual to QCD-like theories.

We study the purely leptonic $W$ decays $W^{+}\to e^{+}{\mu }^{-}{e}^{+}{\nu }_e$ and $W^{+}\to e^{+}{e}^{+}{\mu }^{-}{\overline{\nu }}_{\mu }$ (or their charge conjugates) produced at the LHC, induced by sterile neutrinos with mass below $M_W$ in the intermediate state. While the first mode is induced by both Dirac or Majorana neutrinos, the second mode is induced only by Majorana neutrinos, as it violates lepton number. We find that, even when the final (anti-)neutrino goes undetected, one could distinguish between these two processes, thus distinguishing the Dirac or Majorana character of the sterile neutrinos, by studying the muon spectrum in the decays.

Recently there has been significant interest in the claim that dark matter axions gravitationally thermalize and form a Bose-Einstein condensate with a cosmologically long-range correlation. This has potential consequences for galactic scale observations. Here we critically examine this claim. We point out that there is an essential difference between the thermalization and formation of a condensate due to repulsive interactions, which can indeed drive long-range order, and that due to attractive interactions, which can lead to localized Bose clumps (stars or solitons) that only exhibit short-range correlation. While the difference between repulsion and attraction is not present in the standard collisional Boltzmann equation, we argue that it is essential to the field theory dynamics, and we explain why the latter analysis is appropriate for a condensate. Since the axion is primarily governed by attractive interactions—gravitation and scalar-scalar contact interactions—we conclude that while a Bose-Einstein condensate is formed, the claim of long-range correlation is unjustified.

We show that the number of observed voids in galaxy redshift surveys is a sensitive function of the equation of state of dark energy. Using the Fisher matrix formalism, we find the error ellipses in the $w_0\text{−}{w}_a$ plane when the equation of state of dark energy is assumed to be of the form $w_{\mathrm{CPL}}(z)=w_0+w_{a}z/(1+z)$. We forecast the number of voids to be observed with the ESA Euclid satellite and the NASA WFIRST mission, taking into account updated details of the surveys to reach accurate estimates of their power. The theoretical model for the forecast of the number of voids is based on matches between abundances in simulations and the analytical prediction. To take into account the uncertainties within the model, we marginalize over its free parameters when calculating the Fisher matrices. The addition of the void abundance constraints to the data from Planck, HST and supernova survey data noticeably tighten the $w_0\text{−}{w}_a$ parameter space. We, thus, quantify the improvement in the constraints due to the use of voids and demonstrate that the void abundance is a sensitive new probe for the dark energy equation of state.

Using superconformal methods we derive an explicit de Sitter supergravity action invariant under spontaneously broken local $\mathcal{N}=1$ supersymmetry. The supergravity multiplet interacts with a nilpotent Goldstino multiplet. We present a complete locally supersymmetric action including the graviton and the fermionic fields, gravitino and Goldstino, no scalars. In the global limit when the supergravity multiplet decouples, our action reproduces the Volkov-Akulov theory. In the unitary gauge where the Goldstino vanishes we recover pure supergravity with the positive cosmological constant. The classical equations of motion, with all fermions vanishing, have a maximally symmetric solution: de Sitter space.

We present a new model of stealth dark matter: a composite baryonic scalar of an $SU(N_D)$ strongly coupled theory with even $N_D\ge 4$. All mass scales are technically natural, and dark matter stability is automatic without imposing an additional discrete or global symmetry. Constituent fermions transform in vectorlike representations of the electroweak group that permit both electroweak-breaking and electroweak-preserving mass terms. This gives a tunable coupling of stealth dark matter to the Higgs boson independent of the dark matter mass itself. We specialize to $SU(4)$, and investigate the constraints on the model from dark meson decay, electroweak precision measurements, basic collider limits, and spin-independent direct detection scattering through Higgs exchange. We exploit our earlier lattice simulations that determined the composite spectrum as well as the effective Higgs coupling of stealth dark matter in order to place bounds from direct detection, excluding constituent fermions with dominantly electroweak-breaking masses. A lower bound on the dark baryon mass $m_B\gtrsim 300\mathrm{GeV}$ is obtained from the indirect requirement that the lightest dark meson not be observable at LEP II. We briefly survey some intriguing properties of stealth dark matter that are worthy of future study, including collider studies of dark meson production and decay; indirect detection signals from annihilation; relic abundance estimates for both symmetric and asymmetric mechanisms; and direct detection through electromagnetic polarizability, a detailed study of which will appear in a companion paper.

Our recently developed variant of variationally optimized perturbation, in particular consistently incorporating renormalization group properties, is adapted to the calculation of the QCD spectral density of the Dirac operator and the related chiral quark condensate $⟨\overline{q}q⟩$ in the chiral limit, for $n_f=2$ and $n_f=3$ massless quarks. The results of successive sequences of approximations at two-, three-, and four-loop orders of this modified perturbation exhibit a remarkable stability. We obtain $⟨\overline{q}q{⟩}_{n_f=2}^{1/3}(2\mathrm{GeV})=-(0.833–0.845){\overline{\mathrm{\Lambda }}}_2$, and $⟨\overline{q}q{⟩}_{n_f=3}^{1/3}(2\mathrm{GeV})=-(0.814–0.838){\overline{\mathrm{\Lambda }}}_3$ where the range spanned by the first and second numbers (respectively, four- and three-loop order results) defines our theoretical error, and ${\overline{\mathrm{\Lambda }}}_{n_f}$ is the basic QCD scale in the $\overline{\mathrm{MS}}$ scheme. We obtain a moderate suppression of the chiral condensate when going from $n_f=2$ to $n_f=3$. We compare these results with some other recent determinations from other nonperturbative methods (mainly lattice and spectral sum rules).

The NEMO-3 detector, which had been operating in the Modane Underground Laboratory from 2003 to 2010, was designed to search for neutrinoless double-$\beta$ ($0\nu \beta \beta$) decay. We report the final results of a search for $0\nu \beta \beta$ decays with 6.914 kg of ${}^{100}\mathrm{Mo}$ using the entire NEMO-3 data set with a detector live time of 4.96 yr, which corresponds to an exposure of $34.3\mathrm{kg}·\mathrm{yr}$. We perform a detailed study of the expected background in the $0\nu \beta \beta$ signal region and find no evidence of $0\nu \beta \beta$ decays in the data. The level of observed background in the $0\nu \beta \beta$ signal region [2.8–3.2] MeV is $0.44\pm 0.13\mathrm{counts}/\mathrm{yr}/\mathrm{kg}$, and no events are observed in the interval [3.2–10] MeV. We therefore derive a lower limit on the half-life of $0\nu \beta \beta$ decays in ${}^{100}\mathrm{Mo}$ of $T_{1/2}(0\nu \beta \beta )>1.1\times 10^{24}\mathrm{yr}$ at the 90% confidence level, under the hypothesis of decay kinematics similar to that for light Majorana neutrino exchange. Depending on the model used for calculating nuclear matrix elements, the limit for the effective Majorana neutrino mass lies in the range $⟨m_{\nu }⟩<0.33–0.62\mathrm{eV}$. We also report constraints on other lepton-number violating mechanisms for $0\nu \beta \beta$ decays.

Using the canonical Arnowitt–Deser–Misner Hamiltonian formalism, a “first law of mechanics” is established for binary systems of point masses moving along generic stable bound (eccentric) orbits. This relationship is checked to hold within the post-Newtonian approximation to general relativity, up to third order. Several applications are discussed, including the use of gravitational self-force results to inform post-Newtonian theory and the effective one-body model for eccentric-orbit compact binaries.

A measurement of primordial non-Gaussianity will be of paramount importance to distinguish between different models of inflation. Cosmic microwave background (CMB) anisotropy observations have set unprecedented bounds on the non-Gaussianity parameter $f_{\mathrm{NL}}$ but the interesting regime $f_{\mathrm{NL}}\lesssim 1$ is beyond their reach. Brightness-temperature fluctuations in the 21-cm line during the dark ages ($z\sim 30–100$) are a promising successor to CMB studies, giving access to a much larger number of modes. They are, however, intrinsically nonlinear, which results in secondary non-gaussianities orders of magnitude larger than the sought-after primordial signal. In this paper we carefully compute the primary and secondary bispectra of 21-cm fluctuations on small scales. We use the flat-sky formalism, which greatly simplifies the analysis, while still being very accurate on small angular scales. We show that the secondary bispectrum is highly degenerate with the primordial one, and argue that even percent-level uncertainties in the amplitude of the former lead to a bias of order $\mathrm{\Delta }{f}_{\mathrm{NL}}\sim 10$. To tackle this problem we carry out a detailed Fisher analysis, marginalizing over the amplitudes of a few smooth redshift-dependent coefficients characterizing the secondary bispectrum. We find that the signal-to-noise ratio for a single redshift slice is reduced by a factor of $\sim 5$ in comparison to a case without secondary non-gaussianities. Setting aside foreground contamination, we forecast that a cosmic-variance-limited experiment observing 21-cm fluctuations over $30\le z\le 100$ with a 0.1-MHz bandwidth and 0.1 arc min angular resolution could achieve a sensitivity of order $f_{\mathrm{NL}}^{\text{local}}\sim 0.03$, $f_{\mathrm{NL}}^{\text{equil}}\sim 0.04$ and $f_{\mathrm{NL}}^{\text{ortho}}\sim 0.03$.

We study the behavior of the tree-level S-matrix of a variety of theories as two particles become soft. By analogy with the recently found subleading soft theorems for gravitons and gluons, we explore subleading terms in double soft emissions. We first consider double soft scalar emissions and find subleading terms that are controlled by the angular momentum operator acting on hard particles. The order of the subleading theorems depends on the presence or not of color structures. Next we obtain a compact formula for the leading term in a double soft photon emission. The theories studied are a special Galileon, Dirac–Born–Infeld, Einstein–Maxwell–Scalar, nonlinear sigma model and Yang–Mills–Scalar. We use the recently found Cachazo–He–Yuan representation of these theories in order to give a simple proof of the leading order part of all these theorems.

Planetary ephemerides are a very powerful tool to constrain deviations from the theory of general relativity (GR) using orbital dynamics. The effective field theory framework called the Standard-Model Extension (SME) has been developed in order to systematically parametrize hypothetical violations of Lorentz symmetry (in the Standard Model and in the gravitational sector). In this communication, we use the latest determinations of the supplementary advances of the perihelia and of the nodes obtained by planetary ephemerides analysis to constrain SME coefficients from the pure gravity sector and also from gravity-matter couplings. Our results do not show any deviation from GR and they improve current constraints. Moreover, combinations with existing constraints from Lunar Laser Ranging and from atom interferometry gravimetry allow us to disentangle contributions from the pure gravity sector from the gravity-matter couplings.

We present the first numerical calculation of the (local) metric perturbation produced by a small compact object moving on an eccentric equatorial geodesic around a Kerr black hole, accurate to first order in the mass ratio. The procedure starts by first solving the Teukolsky equation to obtain the Weyl scalar ${\psi }_4$ using semianalytical methods. The metric perturbation is then reconstructed from ${\psi }_4$ in an (outgoing) radiation gauge, adding the appropriate nonradiative contributions arising from the shifts in mass and angular momentum of the spacetime. As a demonstration we calculate the generalized redshift $U$ as a function of the orbital frequencies ${\mathrm{\Omega }}_r$ and ${\mathrm{\Omega }}_{\varphi }$ to linear order in the mass ratio, a gauge invariant measure of the conservative corrections to the orbit due to self-interactions. In Schwarzschild, the results surpass the existing result in the literature in accuracy, and we find new estimates for some of the unknown 4PN and 5PN terms in the post-Newtonian expansion of $U$. In Kerr, we provide completely novel values of $U$ for eccentric equatorial orbits. Calculation of the full self-force will appear in a forthcoming paper.