Recently the Experiment to Detect the Global Epoch of Reionization Signature reported the detection of a 21 cm absorption signal stronger than astrophysical expectations. In this paper we study the impact of radiation from dark matter (DM) decay and primordial black holes (PBHs) on the 21 cm radiation temperature in the reionization epoch, and impose a constraint on the decaying dark matter and PBH energy injection in the intergalactic medium, which can heat up neutral hydrogen gas and weaken the 21 cm absorption signal. We assume a strong coupling limit in the Lyman-$\alpha$ background and consider decay channels $\mathrm{DM}\to e^{+}{e}^{-},\gamma \gamma$, ${\mu }^{+}{\mu }^{-}$, ${\tau }^{+}{\tau }^{-}$, $b\overline{b}$ and the $10^{15–17}\mathrm{g}$ mass range for primordial black holes, and require that the heating of the neutral hydrogen does not negate the 21 cm absorption signal. For $e^{+}{e}^{-}$, $\gamma \gamma$ final states and PBH cases we find strong 21 cm bounds that can be more stringent than the current extragalactic diffuse photon bounds. For the $\mathrm{DM}\to e^{+}{e}^{-}$ channel, the lifetime bound is ${\tau }_{\mathrm{DM}}>{10}^{27}\mathrm{s}$ for sub-GeV dark matter. The bound is ${\tau }_{\mathrm{DM}}\ge {10}^{26}\mathrm{s}$ for the sub-GeV $\mathrm{DM}\to \gamma \gamma$ channel and reaches $10^{27}\mathrm{s}$ for MeV DM. For $b\overline{b}$ and ${\mu }^{+}{\mu }^{-}$ cases, the 21 cm constraint is better than all the existing constraints for $m_{\mathrm{DM}}<30\mathrm{GeV}$ where the bound on ${\tau }_{\mathrm{DM}}\ge {10}^{26}\mathrm{s}$. For both DM decay and primordial black hole cases, the 21 cm bounds significantly improve over the cosmic microwave background damping limits from Planck data.

The search for the QCD critical point in heavy-ion collision experiments requires dynamical simulations of the bulk evolution of QCD matter as well as of fluctuations. We consider two essential ingredients of such a simulation: a generic extension of hydrodynamics by a parametrically slow mode or modes (“$\mathrm{Hydro}+$”) and a description of fluctuations out of equilibrium. By combining the two ingredients, we are able to describe the bulk evolution and the fluctuations within the same framework. Critical slowing-down means that equilibration of fluctuations could be as slow as hydrodynamic evolution, and thus fluctuations could significantly deviate from equilibrium near the critical point. We generalize hydrodynamics to partial-equilibrium conditions where the state of the system is characterized by the off-equilibrium magnitude of fluctuations in addition to the usual hydrodynamic variables—conserved densities. We find that the key element of the new formalism—the extended entropy taking into account the off-equilibrium fluctuations—is remarkably similar to the 2PI action in the quantum field theory. We show how the new $\mathrm{Hydro}+$ formalism reproduces two major effects of critical fluctuations on the bulk evolution: the strong frequency dependence of the anomalously large bulk viscosity as well as the stiffening of the equation of state with an increasing frequency or wave number. While the agreement with known results confirms its validity, the fact that $\mathrm{Hydro}+$ achieves this within a local and deterministic framework gives it significant advantages for dynamical simulations.

We find a class of scale-anomaly-free $\mathcal{N}=2$ supersymmetric quantum systems with nonvanishing potential terms where space and time scale with distinct exponents. Our results generalize the known case of the supersymmetric inverse square potential to a larger class of scaling symmetries.

We investigate the reach at the LHC to probe light sterile neutrinos with displaced vertices. We focus on sterile neutrinos $N$ with masses $m_N\sim (5–30)\mathrm{GeV}$ that are produced in rare decays of the standard model gauge bosons and decay inside the inner trackers of the LHC detectors. With a strategy that triggers on the prompt lepton accompanying the $N$ displaced vertex and considers charged tracks associated with it, we show that the 13 TeV LHC with $3000/\mathrm{fb}$ is able to probe active-sterile neutrino mixings down to $|V_{lN}{|}^2\approx {10}^{-9}$, with $l=e$, $\mu$, which is an improvement of up to 4 orders of magnitude when comparing with current experimental limits from trileptons and proposed lepton-jets searches. In the case when $\tau$ mixing is present, mixing angles as low as $|V_{\tau N}{|}^2\approx {10}^{-8}$ can be accessed.

This paper explores the derivation of dark energy from a locally conformal projection of hyperconical universes. It focuses on the analysis of theoretical compatibility between the intrinsic view of the standard cosmology and an adequate transformation of hyperconical manifolds. Choosing some parametric family of locally conformal transformations and taking regional (second order) equality between the Hubble parameter of both theories, it is predicted that the dark energy density is ${\mathrm{\Omega }}_{\mathrm{\Lambda }}=0.6937181(2)$. In particular, we used a radially distorted stereographic projection, the distortion parameter of which is theoretically predicted about $\alpha =0.325\pm 0.005$ and empirically fitted as $\alpha =0.36\pm 0.02$ (${\chi }_0^2=562$) according to 580 SNe Ia observations.

We extend the general relativistic Lagrangian perturbation theory, recently developed for the formation of cosmic structures in a dust continuum, to the case of model universes containing a single fluid with a single-valued analytic equation of state. Using a coframe-based perturbation approach, we investigate evolution equations for structure formation in pressure-supported irrotational fluids that generate their rest-frame spacetime foliation. We provide master equations to first order for the evolution of the trace and traceless parts of barotropic perturbations that evolve in the perturbed space, where the latter describes the propagation of gravitational waves in the fluid. We illustrate the trace evolution for a linear equation of state and for a model equation of state describing isotropic velocity dispersion, and we discuss differences to the dust matter model, to the Newtonian case, and to standard perturbation approaches.

We analyze the unique capability of the existing SeaQuest experiment at Fermilab to discover well-motivated dark sector physics by measuring displaced electron, photon, and hadron decay signals behind a compact shield. A planned installation of a refurbished electromagnetic calorimeter could provide powerful new sensitivity to GeV-scale vectors, dark Higgs bosons, scalars, axions, and inelastic and strongly interacting dark matter models. This sensitivity is both comparable and complementary to NA62, SHiP, and FASER. SeaQuest’s ability to collect data now and over the next few years provides an especially exciting opportunity.

Within the context of composite Higgs models, recent hints on lepton flavor nonuniversality in $B$ decays can be explained by a vector resonance $V$ with sizeable couplings to the Standard Model leptons ($\ell$). We argue that, in such a case, spin-$1/2$ leptonic resonances ($L$) are most probably light enough to open the decay mode $V\to L\ell$. This implies, in combination with the fact that couplings between composite resonances are much larger than those between composite and elementary fields, that this new decay can be important. In this paper, we explore under which conditions it dominates over other decay modes. Its discovery, however, requires a dedicated search strategy. Employing jet substructure techniques, we analyze the final state with largest branching ratio, namely ${\mu }^{+}{\mu }^{-}Z/h,Z/h\to$ jets. We show that (i) parameter space regions that were believed excluded by dimuon searches are still allowed, (ii) these regions can already be tested with the dedicated search we propose and (iii) $V$ masses as large as $\sim 3.5\mathrm{TeV}$ can be probed at the LHC during the high-luminosity phase.

In this paper, a follow-up of [S. C. Chuliá, R. Srivastava, and J. W. F. Valle, Phys. Lett. B 781, 122 (2018)], we describe the many pathways to generate Dirac neutrino mass through dimension-six operators. By using only the standard model Higgs doublet in the external legs, one gets a unique operator $\frac{1}{{\mathrm{\Lambda }}^2}\overline{L}\overline{\mathrm{\Phi }}\overline{\mathrm{\Phi }}\mathrm{\Phi }{\nu }_R$. In contrast, the presence of new scalars implies new possible field contractions, which greatly increase the number of possibilities. Here, we study in detail the simplest ones, involving $SU(2{)}_L$ singlets, doublets, and triplets. The extra symmetries needed to ensure the Dirac nature of neutrinos can also be responsible for stabilizing dark matter.

We investigate the potential collider signatures of singly charged and doubly charged Higgs bosons such as those arising in minimal left-right symmetric models. Focusing on multileptonic probes in the context of the high-luminosity run of the Large Hadron Collider, we separately assess the advantages of the four-leptonic and trileptonic final states for a representative benchmark setup designed by considering a large set of experimental constraints. Our study establishes possibilities of identifying singly charged and doubly charged scalars at the Large Hadron Collider with a large significance, for luminosity goals expected to be reached during the high-luminosity phase of the Large Hadron Collider. We generalize our results and demonstrate that existing limits can in principle be pushed much further in the heavy mass regime.

In recent years the Tsallis statistics is gaining popularity in describing charged particle production and their properties, in particular $p_T$ spectra and the multiplicities in high energy particle collisions. Motivated by its success, an analysis of the LHC data of proton-proton collisions at energies ranging from 0.9 to 7 TeV in different rapidity windows for charged particle multiplicities has been done. A comparative analysis is performed in terms of the Tsallis distribution, the Gamma distribution and the shifted-Gamma distribution. An interesting observation on the inapplicability of these distributions at $\sqrt{s}=7\mathrm{TeV}$ in the lower rapidity windows is intriguing. The nonextensive nature of the Tsallis statistics is studied by determining the entropic index and its energy dependence. A two-component approach in terms of fractions of events without minijets and events with minijets is applied to improve the fittings. The analysis is extrapolated to predict the multiplicity distribution at $\sqrt{s}=14\mathrm{TeV}$ for one rapidity window, $|y|<1.5$ with the Tsallis function.

We use the complexity equals action proposal to calculate the rate of complexity growth for field theories that are the holographic duals of asymptotically flat spacetimes. To this aim, we evaluate the on-shell action of asymptotically flat spacetime on the Wheeler-DeWitt patch. This results in the same expression as can be found by taking the flat-space limit from the corresponding formula related to the asymptotically AdS spacetimes. For the bulk dimensions that are greater than three, the rate of complexity growth at late times approaches from above to Lloyd’s bound. However, for the three-dimensional bulks, this rate is a constant and differs from Lloyd’s bound by a logarithmic term.

In this paper, we argue that holographic complexity should be a basis-dependent quantity. Computational complexity of a state is defined as a minimum number of gates required to obtain that state from the reference state. Due to this minimality, it satisfies the triangle inequality and can be regarded as a (discrete version of) distance in the Hilbert space. However, we show a no-go theorem that any basis-independent distance cannot reproduce the behavior of the holographic complexity. Therefore, if holographic complexity is dual to a distance in the Hilbert space, it should be basis dependent; i.e., it is not invariant under a change of the basis of the Hilbert space.

In this paper, we show that the soft behavior of photons and graviton amplitudes, after projection, can be determined to infinite order in soft expansion via ordinary on-shell gauge invariance. In particular, as one of the particle’s momenta becomes soft, gauge invariance relates the nonsingular diagrams of an $n$-point amplitude to that of the singular ones up to possible homogeneous terms. We demonstrate that with a particular projection of the soft limit the homogeneous terms do not contribute, and one arrives at an infinite soft theorem. This reproduces the result recently derived from the Ward identity of large gauge transformations. We also discuss the modification of these soft theorems due to the presence of higher-dimensional operators.

We present a prescription for computing gravitational waveforms for the inspiral, merger and ringdown of nonspinning moderately eccentric binary black hole systems. The inspiral waveform is computed using the post-Newtonian expansion and the merger waveform is computed by interpolating a small number of quasicircular NR waveforms. The use of circular merger waveforms is possible because binaries with moderate eccentricity circularize in the last few cycles before the merger, which we demonstrate up to mass ratio $q=m_1/m_2=3$. The complete model is calibrated to 23 numerical relativity (NR) simulations starting $\approx 20$ cycles before the merger with eccentricities $e_{\mathrm{ref}}\le 0.1$ and mass ratios $q\le 3$, where $e_{\mathrm{ref}}$ is the eccentricity $\approx 7$ cycles before the merger. The NR waveforms are long enough that they start below 30 Hz (10 Hz) for BBH systems with total mass $M\ge 80M_{\odot }$ ($230M_{\odot }$). We find that, for the sensitivity of advanced LIGO at the time of its first observing run, the eccentric model has a faithfulness with NR of over 97% for systems with total mass $M\ge 85M_{\odot }$ across the parameter space ($e_{\mathrm{ref}}\le 0.1$, $q\le 3$). For systems with total mass $M\ge 70M_{\odot }$, the faithfulness is over 97% for $e_{\mathrm{ref}}\lesssim 0.05$ and $q\le 3$. The NR waveforms and the Mathematica code for the model are publicly available.

We describe a procedure for constructing initial data for boosted black holes in the moving-punctures approach to numerical relativity that endows the initial time slice from the outset with trumpet geometry within the black hole interiors. We then demonstrate the procedure in numerical simulations using an evolution code from the Einstein Toolkit that employs $1+\log$ slicing. By using boosted Kerr-Schild geometry as an intermediate step in the construction, the Lorentz boost of a single black hole can be precisely specified and multiple, widely separated black holes can be treated approximately by superposition of single hole data. There is room within the scheme for later improvement to resolve (iterate) the constraint equations in the multiple black hole case. The approach is shown to yield an initial trumpet slice for one black hole that is close to, and rapidly settles to, a stationary trumpet geometry. By avoiding the assumption of conformal flatness, initial data in this new approach is shown to contain initial transient (or “junk”) radiation that is suppressed by as much as 2 orders of magnitude relative to that in comparable Bowen-York initial data.

We introduce gravity theories featuring spontaneously growing gauge fields where the growth is due to the Higgs mechanism. The underlying physics is inspired by the spontaneous scalarization phenomena in scalar-tensor theories. The tachyonic instability that causes the growth in spontaneous scalarization and its analog for vector fields is introduced not as an explicit potential term, but through a scalar coupling using a Higgs field. The resulting theories are distinct from previous examples of spontaneous tensorization in that they respect the gauge symmetry at the level of the action. Our results are valid for both Abelian and non-Abelian gauge theories, and this is the first study of the spontaneous growth of the latter. We discuss astrophysical implications of these theories and argue their relevance, especially in the strong gravity regime.

In this work, we find novel static and spherically symmetric wormhole geometries using a three-form field. By solving the gravitational field equations, we find a variety of analytical and numerical solutions and show that it is possible for the matter fields threading the wormhole to satisfy the null and weak energy conditions throughout the spacetime, when the three-form field is present. In these cases, the form field is responsible for supporting the wormhole and all the exoticity is confined to it. Thus, the three-form curvature terms, which may be interpreted as a gravitational fluid, sustain these wormhole geometries. We also show that in the case of a vanishing redshift function the field can display a cosmological constant behavior.

We show that spinor fields nonminimally coupled to gravity can grow spontaneously in the presence of matter. We name this phenomenon spontaneous spinorization after the spontaneous scalarization scenario in scalar-tensor theories. Underlying reason for the growth of the spinor is an instability similar to the tachyon of spontaneous scalarization. We first present the structure of a tachyonic Dirac equation, and incorporate it into the matter coupling in gravity. This causes the zero-spinor solution to be unstable and leads to spontaneous growth. We investigate the behavior of the resulting theory for a spherically symmetric neutron star that has grown a spinor cloud. Spontaneous spinorization has the potential to lead to order-of-unity deviations from general relativity in strong fields in a similar manner to its close relative spontaneous scalarization. This makes the theory especially relevant to gravitational wave science and neutron star astrophysics.