The capture of dark matter by the Sun and its subsequent annihilation may produce an observable feature in the solar neutrino spectrum. We analyze this possibility in the case where the dark matter takes the form of heavy nuggets of quark matter. In this scenario neutrinos are produced in nuclear annihilations deep within the quark matter. The production of neutrinos and antineutrinos at typical nuclear annihilation energies in the 20–50 MeV range is strongly constrained by data from Super-Kamiokande and in this region there is no background from conventional solar processes. However, we demonstrate that a cascade generated by a nuclear annihilation within the nuggets rapidly transfers its energy down to the lightest pseudo-Goldstone mesons (the pions and Kaons) which have masses in the $\lesssim 20\mathrm{MeV}$ range, significantly lighter than the vacuum mesons for which $m_{\pi }\simeq 140\mathrm{MeV}$. Thus, the decay of these light pseudo-Goldstone modes of the quark matter phase will not produce neutrinos at the same scale as those seen from annihilations occurring in vacuum. In this work we predict the basic properties of the resulting neutrino spectrum and argue that, while nuggets composed of purely nuclear matter would be effectively ruled out by present neutrino flux constraints, there remains a wide class of viable models. Furthermore, we emphasize the potential for continued neutrino observations with the current generation of detectors to offer a strong test of these models.

Terrestrial searches for the conversion of dark matter axions or axionlike particles into photons inside magnetic fields are sensitive to the phase space structure of the local Milky Way halo. We simulate signals in a hypothetical future experiment based on the Axion Dark Matter Experiment that could be performed once the axion has been detected and a frequency range containing the axion mass has been identified. We develop a statistical analysis to extract astrophysical parameters, such as the halo velocity dispersion and laboratory velocity, from such data and find that with only a few days integration time a level of precision can be reached, matching that of astronomical observations. For longer experiments lasting up to a year in duration, we find that exploiting the modulation of the power spectrum in time allows accurate measurements of the Solar peculiar velocity with an accuracy that would improve upon astronomical observations. We also simulate signals based on results from N-body simulations and find that finer substructure in the form of tidal streams would show up prominently in future data, even if only a subdominant contribution to the local dark matter distribution. In these cases, it would be possible to reconstruct all the properties of a dark matter stream using the time and frequency dependence of the signal. Finally, we consider the detection prospects for a network of streams from tidally disrupted axion miniclusters. These features appear much more prominently in the resolved spectrum than suggested by calculations based on a scan over a range of resonant frequencies, making the detection of axion minicluster streams more viable than previously thought. These results confirm that haloscope experiments in a postdiscovery era are able to perform “axion astronomy.”

Merging binary neutron stars (BNSs) represent the ultimate targets for multimessenger astronomy, being among the most promising sources of gravitational waves (GWs), and, at the same time, likely accompanied by a variety of electromagnetic counterparts across the entire spectrum, possibly including short gamma-ray bursts (SGRBs) and kilonova/macronova transients. Numerical relativity simulations play a central role in the study of these events. In particular, given the importance of magnetic fields, various aspects of this investigation require general relativistic magnetohydrodynamics (GRMHD). So far, most GRMHD simulations focused the attention on BNS mergers leading to the formation of a hypermassive neutron star (NS), which, in turn, collapses within few tens of ms into a black hole surrounded by an accretion disk. However, recent observations suggest that a significant fraction of these systems could form a long-lived NS remnant, which will either collapse on much longer time scales or remain indefinitely stable. Despite the profound implications for the evolution and the emission properties of the system, a detailed investigation of this alternative evolution channel is still missing. Here, we follow this direction and present a first detailed GRMHD study of BNS mergers forming a long-lived NS. We consider magnetized binaries with different mass ratios and equations of state and analyze the structure of the NS remnants, the rotation profiles, the accretion disks, the evolution and amplification of magnetic fields, and the ejection of matter. Moreover, we discuss the connection with the central engine of SGRBs and provide order-of-magnitude estimates for the kilonova/macronova signal. Finally, we study the GW emission, with particular attention to the post-merger phase.

Stellar core collapse events are expected to produce gravitational waves via several mechanisms, most of which are not yet fully understood due to the current limitations in the numerical simulations of these events. In this paper, we begin with an empirical functional form that fits the gravitational-wave spectra from existing simulations of stellar core collapse and integrate over all collapse events in the Universe to estimate the resulting stochastic gravitational-wave background. We then use a Gaussian functional form to separately fit and model a low-frequency peak in the core-collapse strain spectra, which likely occurs due to prompt convection. We systematically study the parameter space of both models, as well as the combined case, and investigate their detectability by upcoming gravitational-wave detectors, such as Advanced LIGO and the Einstein Telescope. Assuming realistic formation rates for progenitors of core-collapse supernovae, our results indicate that both models are 2–4 orders of magnitude below the expected sensitivity of Advanced LIGO, and 1–2 orders of magnitude below that of the Einstein Telescope.

Hardware injections are simulated gravitational-wave signals added to the Laser Interferometer Gravitational-wave Observatory (LIGO). The detectors’ test masses are physically displaced by an actuator in order to simulate the effects of a gravitational wave. The simulated signal initiates a control-system response which mimics that of a true gravitational wave. This provides an end-to-end test of LIGO’s ability to observe gravitational waves. The gravitational-wave analyses used to detect and characterize signals are exercised with hardware injections. By looking for discrepancies between the injected and recovered signals, we are able to characterize the performance of analyses and the coupling of instrumental subsystems to the detectors’ output channels. This paper describes the hardware injection system and the recovery of injected signals representing binary black hole mergers, a stochastic gravitational wave background, spinning neutron stars, and sine-Gaussians.

We propose a variant of the $D4\text{−}D8$ construction to describe the low-energy effective theory of heavy-light mesons, interacting with the lowest lying pseudoscalar and vector mesons. The heavy degrees of freedom are identified with the $D{8}_L\text{−}D{8}_H$ string low-energy modes, and are approximated near the world volume of $N_f-1$ light $D{8}_L$ branes, by fundamental vector field valued in $U(N_f-1)$. The effective action follows from the reduction of the bulk Dirac-Born-Infeld and Chern-Simons actions, and is shown to exhibit both chiral and heavy-quark symmetry. The action interpolates continuously between the $U(N_f)$ case with massless mesons, and the $U(N_f-1)$ case with heavy-light mesons. The heavy-light meson radial spectrum is Regge-like. The one-pion and two-pion couplings to the heavy-light multiplets are evaluated. The partial widths for the charged decays $G\to H+\pi$ are shown to be comparable to the recently reported full widths for both the charm and bottom mesons.

We extend our analysis of quasidistributions onto the pion distribution amplitude. Using the formalism of parton virtuality distribution amplitudes, we establish a connection between the pion transverse momentum dependent distribution amplitude $\mathrm{\Psi }(x,k_{\perp }^2)$ and the pion quasidistribution amplitude (QDA) $Q_{\pi }(y,p_3)$. We build models for the QDAs from the virtuality-distribution-amplitude-based models for soft transverse momentum dependent distribution amplitudes, and analyze the $p_3$ dependence of the resulting QDAs. As there are many models claimed to describe the primordial shape of the pion distribution amplitude, we present the $p_3$-evolution patterns for models producing some popular proposals: Chernyak-Zhitnitsky, flat, and asymptotic distribution amplitude. Our results may be used as a guide for future studies of the pion distribution amplitude on the lattice using the quasidistribution approach.

We explore the ability of current and future dark matter and collider experiments in probing the anomalous magnetic moment of the muon, $(g-2{)}_{\mu }$, within the minimal supersymmetric standard model (MSSM). We find that the latest PandaX-II/LUX-2016 data give a strong constraint on parameter space that accommodates the $(g-2{)}_{\mu }$ within the $2\sigma$ range, which will be further excluded by the upcoming XENON-1T (2017) experiment. We also find that a 100 TeV $pp$ collider can cover most of our surviving samples that satisfy dark matter (DM) relic density within the $3\sigma$ range through the $Z$ or $h$ resonant effect by searching for trilepton events from ${\tilde{\chi }}_2^0{\tilde{\chi }}_1^{+}$ associated production. The samples that are beyond future sensitivity of the trilepton search at a 100 TeV $pp$ collider and the DM direct detections are either Higgsino/winolike lightest supersymmetric partilces (LSPs) or binolike LSPs coannihilating with sleptons. Such compressed regions may be covered by the monojet(like) searches at a 100 TeV $pp$ collider.

In this paper, we study the possibility of an inhomogeneous quark condensate in the ($1+1$)-dimensional Nambu-Jona-Lasinio model in the large-$N_c$ limit at finite temperature $T$ and quark chemical potential $\mu$ using dimensional regularization. The phase diagram in the $\mu –T$ plane is mapped out. At zero temperature, an inhomogeneous phase with a chiral-density wave exists for $\mu >{\mu }_c$, where ${\mu }_c$ is a critical chemical potential. Performing a Ginzburg-Landau analysis, we show that in the chiral limit, the tricritical point and the Lifschitz point coincide. We also consider the competition between a chiral-density wave and a constant pion condensate at finite isospin chemical potential ${\mu }_I$. The phase diagram in the ${\mu }_I-\mu$ plane is mapped out and shows a rich phase structure.

Multiquark states have been advocated to explain recent experimental data in the heavy-light sector, and there are already speculations about multiquarks containing only heavy quarks and antiquarks. With a rigorous treatment of the four-body problem in current quark models, full-charm $(cc\overline{c}\overline{c})$ and full-beauty $(bb\overline{b}\overline{b})$ tetraquarks are found to be unbound. Thus their stability should rely on more subtle effects that are not included in the simple picture of constituent quarks. The case of $(bc\overline{b}\overline{c})$ might be more favorable if the naive color-additive model of confinement is replaced by a string-inspired interaction.

We study the motion of a string in the background of a Reissner-Nordstrom black hole, in both anti–de Sitter as well as asymptotically flat spacetimes. We describe the phase space of this dynamical system through the largest Lyapunov exponent, Poincaré sections and basins of attraction. We observe that string motion in these settings is particularly chaotic and comment on its characteristics.

We study the momentum space entanglement between different energy modes of interacting scalar fields propagating in general ($D+1$)-dimensional flat space-time. As opposed to some of the recent works [V. Balasubramanian et al., Phys. Rev. D 86, 045014 (2012)], we use a Lorentz invariant normalized ground state to obtain the momentum space entanglement entropy. We show that the Lorenz invariant definition removes the spurious power-law behavior obtained in the earlier works. More specifically, we show that the cubic interacting scalar field in ($1+1$) dimensions leads to logarithmic divergence of the entanglement entropy and is consistent with the results from real space entanglement calculations. We study the effects of the introduction of the Lorentz violating higher derivative terms in the presence of a nonlinear self-interacting scalar field potential and show that the divergence structure of the entanglement entropy is improved in the presence of spatial higher derivative terms.

We analyze the gravitational radiation emitted from a particle in circular motion around a Schwarzschild black hole using the framework of quantum field theory in curved spacetime at tree level. The gravitational perturbations are written in a gauge-invariant formalism for spherically symmetric spacetimes. We discuss the results, comparing them to the radiation emitted by a particle when it is assumed to be orbiting a massive object due to a Newtonian force in flat spacetime.

The success of loop quantum cosmology to resolve classical singularities of homogeneous models has led to its application to the classical Schwarszchild black hole interior, which takes the form of a homogeneous Kantowski-Sachs model. The first steps of this were done in pure quantum mechanical terms, hinting at the traversable character of the would-be classical singularity, and then others were performed using effective heuristic models capturing quantum effects that allowed a geometrical description closer to the classical one but avoided its singularity. However, the problem of establishing the link between the quantum and effective descriptions was left open. In this work, we propose to fill in this gap by considering the path-integral approach to the loop quantization of the Kantowski-Sachs model corresponding to the Schwarzschild black hole interior. We show that the transition amplitude can be expressed as a path integration over the imaginary exponential of an effective action which just coincides, under some simplifying assumptions, with the heuristic one. Additionally, we further explore the consequences of the effective dynamics. We prove first that such dynamics imply some rather simple bounds for phase-space variables, and in turn—remarkably, in an analytical way—they imply that various phase-space functions that were singular in the classical model are now well behaved. In particular, the expansion rate, its time derivative, and the shear become bounded, and hence the Raychaudhuri equation is finite term by term, thus resolving the singularities of classical geodesic congruences. Moreover, all effective scalar polynomial invariants turn out to be bounded.

Conjectures play a central role in theoretical physics, especially those that assert an upper bound to some dimensionless ratio of physical quantities. In this paper we introduce a new such conjecture bounding the ratio of the magnetic moment to angular momentum in nature. We also discuss the current status of some old bounds on dimensionless and dimensional quantities in arbitrary spatial dimension. Our new conjecture is that the dimensionless Schuster-Wilson-Blackett number, $c\mu /J{G}^{\frac{1}{2}}$, where $\mu$ is the magnetic moment and $J$ is the angular momentum, is bounded above by a number of order unity. We verify that such a bound holds for charged rotating black holes in those theories for which exact solutions are available, including the Einstein-Maxwell theory, Kaluza-Klein theory, the Kerr-Sen black hole, and the so-called STU family of charged rotating supergravity black holes. We also discuss the current status of the maximum tension conjecture, the Dyson luminosity bound, and Thorne’s hoop conjecture.

We perform the first numerical simulations of necklaces in a non-Abelian gauge theory. Necklaces are composite classical solutions which can be interpreted as monopoles trapped on strings, rather generic structures in a Grand Unified Theory. We generate necklaces from random initial conditions, modeling a phase transition in the early Universe, and study the evolution. For all cases, we find that the necklace system shows scaling behavior similar to that of a network of ordinary cosmic strings. Furthermore, our simulations indicate that comoving distance between the monopoles or semipoles along the string asymptotes to a constant value at late times. This means that, while the monopole-to-string energy density ratio decreases as the inverse of the scale factor, a horizon-size length of string has a large number of monopoles, significantly affecting the dynamics of string loops. We argue that gravitational wave bounds from millisecond pulsar timing on the string tension in the Nambu-Goto scenario are greatly relaxed.

We extend the study of long-mode perturbations to other large-scale observables such as cosmic rulers, galaxy-number counts, and halo bias. The long mode is a pure gradient mode that is still outside an observer’s horizon. We insist that gradient-mode effects on observables vanish. It is also crucial that the expressions for observables are relativistic. This allows us to show that the effects of a gradient mode on the large-scale observables vanish identically in a relativistic framework. To study the potential modulation effect of the gradient mode on halo bias, we derive a consistency condition to the first order in gradient expansion. We find that the matter variance at a fixed physical scale is not modulated by the long gradient mode perturbations when the consistency condition holds. This shows that the contribution of long gradient modes to bias vanishes in this framework.

Understanding single pion production reactions on free nucleons is the first step towards a correct description of these processes in nuclei, which are important for signal and background contributions in current and near future accelerator neutrino oscillation experiments. In this work, we reanalyze our previous studies of neutrino-induced one-pion production on nucleons for outgoing $\pi N$ invariant masses below 1.4 GeV. Our motivation is to get a better description of the ${\nu }_{\mu }n\to {\mu }^{-}n{\pi }^{+}$ cross section, for which current theoretical models give values significantly below data. This channel is very sensitive to the crossed $\mathrm{\Delta }(1232)$ contribution and thus, to spin $1/2$ components in the Rarita-Schwinger $\mathrm{\Delta }$ propagator. We show how these spin $1/2$ components are nonpropagating and give rise to contact interactions. In this context, we point out that the discrepancy with experiment might be corrected by the addition of appropriate extra contact terms and argue that this procedure will provide a natural solution to the ${\nu }_{\mu }n\to {\mu }^{-}n{\pi }^{+}$ puzzle. To keep our model simple, in this work, we propose to change the strength of the spin $1/2$ components in the $\mathrm{\Delta }$ propagator and use the ${\nu }_{\mu }n\to {\mu }^{-}n{\pi }^{+}$ data to constraint its value. With this modification, we now find a good reproduction of the ${\nu }_{\mu }n\to {\mu }^{-}n{\pi }^{+}$ cross section without affecting the good results previously obtained for the other channels. We also explore how this change in the $\mathrm{\Delta }$ propagator affects our predictions for pion photoproduction and find also a better agreement with experiment than with the previous model.

Supernova (SN) neutrinos can excite the nuclei of various detector materials beyond their neutron emission thresholds through charged current (CC) and neutral current (NC) interactions. The emitted neutrons, if detected, can be a signal for the supernova event. Here we present the results of our study of SN neutrino detection through the neutron channel in ${}^{208}\mathrm{Pb}$ and ${}^{56}\mathrm{Fe}$ detectors for realistic neutrino fluxes and energies given by the recent Basel/Darmstadt simulations for an 18 solar mass progenitor SN at a distance of 10 kpc. We find that, in general, the number of neutrons emitted per kiloton (kTon) of detector material for the neutrino luminosities and average energies of the different neutrino species as given by the Basel/Darmstadt simulations are significantly lower than those estimated in previous studies based on the results of earlier SN simulations. At the same time, we highlight the fact that, although the total number of neutrons produced per kTon in a ${}^{56}\mathrm{Fe}$ detector is more than an order of magnitude lower than that for ${}^{208}\mathrm{Pb}$, the dominance of the flavor blind NC events in the case of ${}^{56}\mathrm{Fe}$, as opposed to the dominance of ${\nu }_e$ induced CC events in the case of ${}^{208}\mathrm{Pb}$, offers a complementarity between the two detector materials so that simultaneous detection of SN neutrinos in a ${}^{208}\mathrm{Pb}$ and a sufficiently large ${}^{56}\mathrm{Fe}$ detector suitably instrumented for neutron detection may allow estimating the fraction of the total $\mu$ and $\tau$ flavored neutrinos in the SN neutrino flux and thereby probing the emission mechanism as well as flavor oscillation scenarios of the SN neutrinos.