The direct detection of gravitational waves provides the opportunity to measure fundamental aspects of gravity which have never been directly probed before, including the polarization of gravitational waves. In the context of searches for continuous waves from known pulsars, we present novel methods to detect signals of any polarization content, measure the modes present and place upper limits on the amplitude of nontensorial components. This will allow us to obtain new model-independent, dynamical constraints on deviations from general relativity. We test this framework on multiple potential sources using simulated data from three advanced-era detectors at design sensitivity. We find that signals of any polarization will become detectable and distinguishable for characteristic strains $h\gtrsim 3\times {10}^{-27}\sqrt{1\mathrm{yr}/T}$, for an observation time $T$. We also find that our ability to detect nontensorial components depends only on the power present in those modes, irrespective of the strength of the tensorial strain.

We propose a method to identify the direction of an incident weakly interacting massive particle (WIMP) via induced nuclear recoil. Our method is based on spectroscopic interrogation of quantum defects in macroscopic solid-state crystals. When a WIMP scatters in a crystal, the induced nuclear recoil creates a tell-tale damage cluster, localized to within about 50 nm, with an orientation to the damage trail that correlates well with the direction of the recoil and hence the incoming WIMP. This damage cluster induces strain in the crystal, shifting the energy levels of nearby quantum defects. These level shifts can be measured optically (or through paramagnetic resonance) making it possible to detect the strain environment around the defect in a solid sample. As a specific example, we consider nitrogen vacancy centers in diamond, for which high defect densities and nanoscale localization of individual defects have been demonstrated. To localize the millimeter-scale region of a nuclear recoil within the crystal due to a potential dark matter event, we can use conventional WIMP detection techniques such as the collection of ionization/scintillation. Once an event is identified, the quantum defects in the vicinity of the event can be interrogated to map the strain environment, thus determining the direction of the recoil. In principle, this approach should be able to identify the recoil direction with an efficiency greater than 70% at a false-positive rate less than 5% for 10 keV recoil energies. If successful, this method would allow for directional detection of WIMP-induced nuclear recoils at solid-state densities, enabling probes of WIMP parameter space below the solar neutrino floor. This technique could also potentially be applied to identify the direction of particles such as neutrons whose low scattering cross section requires detectors with a large target mass.

In Coulomb gauge a longitudinal electric field is generated instantaneously with the creation of a static quark-antiquark pair. The field due to the quarks is a sum of two contributions, one from the quark and one from the antiquark, and there is no obvious reason that this sum should fall off exponentially with distance from the sources. We show here, however, from numerical simulations in pure SU(2) lattice gauge theory, that the color Coulomb electric field does in fact fall off exponentially with transverse distance away from a line joining static quark-antiquark sources, indicating the existence of a color Coulomb flux tube, and the absence of long-range Coulomb dipole fields.

In the present work, we investigate the spectrum of several low-lying $sscq\overline{q}$ pentaquark configurations employing the constituent quark model, within which the hyperfine interaction between quarks is taken to be mediated by Goldstone boson exchange. Our numerical results show that four $sscq\overline{q}$ configurations with $J^P=1/2^{-}$ or $J^P=3/2^{-}$ lie at energies very close to the recently observed five ${\mathrm{\Omega }}_c^0$ states by the LHCb Collaboration; this indicates that the $sscq\overline{q}$ pentaquark configurations may form sizable components of the observed ${\mathrm{\Omega }}_c^0$ resonances.

The number of nonrelativistic axions can be changed by inelastic reactions that produce photons or relativistic axions. Any odd number of axions can annihilate into two photons. Any even number of nonrelativistic axions can scatter into two relativistic axions. We calculate the rate at which axions are lost from axion stars from these inelastic reactions. In dilute systems of axions, the dominant inelastic reaction is axion decay into two photons. In sufficiently dense systems of axions, the dominant inelastic reaction is the scattering of four nonrelativistic axions into two relativistic axions. The scattering of odd numbers of axions into two photons produces monochromatic radio-frequency signals at odd-integer harmonics of the fundamental frequency set by the axion mass. This provides a unique signature for dense systems of axions, such as a dense axion star or a collapsing dilute axion star.

A new branch of black hole solutions occurs along with the standard Schwarzschild branch in $n$-dimensional extensions of general relativity including terms quadratic in the Ricci tensor. The standard and new branches cross at a point determined by a static negative-eigenvalue eigenfunction of the Lichnerowicz operator, analogous to the Gross-Perry-Yaffe eigenfunction for the Schwarzschild solution in standard $n=4$ dimensional general relativity. This static eigenfunction has two roles: both as a perturbation away from Schwarzschild along the new black-hole branch and also as a threshold unstable mode lying at the edge of a domain of Gregory-Laflamme-type instability of the Schwarzschild solution for small-radius black holes. A thermodynamic analogy with the Gubser and Mitra conjecture on the relation between quantum thermodynamic and classical dynamical instabilities leads to a suggestion that there may be a switch of stability properties between the old and new black-hole branches for small black holes with radii below the branch crossing point.

We construct models of static spherical distributions of the perfect fluid in trace free Einstein gravity theory. The equations governing the gravitational field are equivalent to standard Einstein’s equations; however, their presentation is manifestly different, which motivates the question whether new information would emerge due to the nonlinearity of the field equations. The incompressible fluid assumption does not lead to the well known Schwarzschild interior metric of Einstein gravity, and a term denoting the presence of a cosmological constant is present on account of the integration process. The Schwarzschild interior is regained as a special case of a richer geometry. On the other hand, when the Schwarzschild geometry is prescribed, a constant density fluid emerges consistent with the standard equations. A complete model of an isothermal fluid sphere with pressure and density obeying the inverse square law is obtained. Corrections to the model previously presented in the literature by Saslaw et al. are exhibited. The isothermal ansatz does not yield a constant gravitational potential in general, but both potentials are position dependent. Conversely, it is shown that assuming a constant $g_{rr}$ gravitational potential does not yield an isothermal fluid in general as is the case in standard general relativity. The results of the standard Einstein equations are special cases of the models reported here. Noteworthy is the fact that whereas the previously reported isothermal solution was only of cosmological interest, the solution reported herein admits compact objects by virtue of the fact that a pressure free hypersurface exists. Finally we analyze the consequences of selecting the Finch-Skea metric as the seed solution. The density profiles match; however, there is a deviation between the pressure profiles with the Einstein case although the qualitative behavior is the same. It is shown in detail that the model satisfies elementary requirements for physical plausibility such as a positive density and pressure, existence of a hypersurface of vanishing pressure, a subluminal sound speed, satisfaction of the weak, strong, and dominant energy conditions, as well as the Buchdahl mass–radius compactness requirement.

In this work we study constraints from new searches for heavy particles at the LHC on the allowed masses and couplings of a Kaluza-Klein (KK) graviton in a holographic composite Higgs model. Keeping new electroweak states heavy such that electroweak precision tests are satisfied, we control the mass of the lightest KK graviton using a brane kinetic term. With this we study KK graviton masses from 0.5–3 TeV. In our analysis we also employ little Randall-Sundrum (RS) models, characterized by a lower UV scale in the five-dimensional model which in turn implies modified couplings to massless bulk fields. Viewing this scenario as a strongly coupled four-dimensional theory with a composite Higgs boson, the KK graviton is interpreted as a composite spin-2 state and the varying UV scale corresponds to a varying intermediate scale between the cutoff of the low-energy effective theory and the Planck scale. We find that KK gravitons with masses in the range [500, 3000] GeV are compatible with current collider constraints, where the most promising channels for detecting these states are the diphoton and $ZZ$ channels. A detection is more likely in the little RS models, in which the dual gauge theory has a larger number of colors than in traditional RS models.

The masses of the low-lying baryons are evaluated using an ensemble with two degenerate light twisted mass clover-improved quarks with mass tuned to reproduce the physical pion mass. The Iwasaki improved gluonic action is employed. The coupling constant value corresponds to a lattice spacing of $a=0.0938(3)(2)\mathrm{fm}$, determined from the nucleon mass. We find that the clover term supresses isospin symmetry breaking as compared to our previous results using $N_f=2+1+1$ twisted mass fermions. The masses of the hyperons and charmed baryons evaluated using this ensemble are in agreement with the experimental values. We provide predictions for the mass of the doubly charmed ${\mathrm{\Xi }}_{cc}^{*}$, as well as of the doubly and triply charmed $\mathrm{\Omega }$s that have not yet been determined experimentally.

Statistical moments of particle multiplicities in heavy-ion collision experiments are an important probe in the exploration of the phase diagram of strongly interacting matter and, particularly, in the search for the QCD critical end point. In order to appropriately interpret experimental measures of these moments, however, it is necessary to understand the role of experimental limitations, as well as background contributions, providing expectations on how critical behavior should be affected by them. We here present a framework for calculating moments of particle multiplicities in the presence of correlations of both critical and spurious origins. We also include effects from resonance decay and a limited acceptance window, as well as detector efficiency. Although we focus on second-order moments, for simplicity, an extension to higher-order moments is straightforward.

Using a sample of 106 million $\psi (3686)$ decays, the branching fractions of $\psi (3686)\to \gamma {\chi }_{c0}$, $\psi (3686)\to \gamma {\chi }_{c1}$, and $\psi (3686)\to \gamma {\chi }_{c2}$ are measured with improved precision to be $(9.389\pm 0.014\pm 0.332)\%$, $(9.905\pm 0.011\pm 0.353)\%$, and $(9.621\pm 0.013\pm 0.272)\%$, respectively, where the first uncertainties are statistical and the second ones are systematic. The product branching fractions of $\psi (3686)\to \gamma {\chi }_{c1},{\chi }_{c1}\to \gamma J/\psi$ and $\psi (3686)\to \gamma {\chi }_{c2},{\chi }_{c2}\to \gamma J/\psi$ and the branching fractions of ${\chi }_{c1}\to \gamma J/\psi$ and ${\chi }_{c2}\to \gamma J/\psi$ are also presented.

We propose a new holographic dual of conformal field theory defined on a manifold with boundaries, i.e., boundary conformal field theory (BCFT). Our proposal can apply to general boundaries and agrees with Takayanagi [Phys. Rev. Lett. 107, 101602 (2011)] for the special case of a disk and half-plane. Using the new proposal of $\mathrm{AdS}/\mathrm{BCFT}$, we successfully obtain the expected boundary Weyl anomaly, and the obtained boundary central charges naturally satisfy a c-like theorem holographically. We also investigate the holographic entanglement entropy of BCFT and find that the minimal surface must be normal to the bulk spacetime boundaries when they intersect. Interestingly, the entanglement entropy depends on the boundary conditions of BCFT and the distance to the boundary. The entanglement wedge has an interesting phase transition that is important for the self-consistency of $\mathrm{AdS}/\mathrm{BCFT}$.

We study the coexistence system of both bosonic and fermionic degrees of freedom. Even if a Lagrangian does not include higher derivatives, fermionic ghosts exist. For a Lagrangian with up to first derivatives, we find the fermionic ghost free condition in Hamiltonian analysis, which is found to be the same as requiring that the equations of motion of fermions be first order in Lagrangian formulation. When fermionic degrees of freedom are present, the uniqueness of time evolution is not guaranteed a priori because of the Grassmann property. We confirm that the additional condition, which is introduced to close Hamiltonian analysis, also ensures the uniqueness of the time evolution of the system.

In this paper, the linearly charged three-dimensional Einstein’s theory coupled to a dilatonic field has been considered. It has been shown that the dilatonic potential must be considered in a form of generalized Liouville-type potential. Two new classes of charged dilatonic black hole solutions, as the exact solutions to the Einstein-Maxwell-dilaton (EMd) gravity, have been obtained and their properties have been studied. The conserved charge and mass related to both of the new EMd black holes have been calculated. Through comparison of the thermodynamical extensive quantities (i.e., temperature and entropy) obtained from both, the geometrical and the thermodynamical methods, the validity of first law of black hole thermodynamics has been investigated for both of the new black holes we just obtained. At the final stage, making use of the canonical ensemble method and regarding the black hole heat capacity, the thermal stability or phase transition of the new black hole solutions have been analyzed. It has been shown that there is a specific range for the horizon radius in such a way that the black holes with the horizon radius in that range are locally stable. Otherwise, they are unstable and may undergo type one or type two phase transitions to be stabilized.

I propose an alternative $f(R)$ theory of gravity constructed by applying the function $f$ directly to the Ricci tensor instead of the Ricci scalar. The main goal of this study is to derive the resulting modified Einstein equations for the metric case with the Levi-Cività connection, as well as for the general nonmetric connection with torsion. The modification is then applied to the Robertson-Walker metric so that the cosmological evolution corresponding to the standard model can be studied. An appealing feature is that even in the vacuum case, scenarios without initial singularity and exponential expansion can be recovered. Finally, formulas for possible observational tests are given.

In “modified” gravity the observed acceleration of the universe is explained by changing the gravitational force law or the number of degrees of freedom in the gravitational sector. Both possibilities can be tested by measurements of cosmological structure formation. In this paper we elaborate the details of such tests using the Galileon model as a case study. We pay attention to the possibility that each new degree of freedom may have stochastically independent initial conditions, generating different types of potential well in the early universe and breaking complete correlation between density and velocity power spectra. This “stochastic bias” can confuse schemes to parametrize the predictions of modified gravity models, such as the use of the growth parameter $f$ alone. Using data from the WiggleZ Dark Energy Survey we show that it will be possible to obtain constraints using information about the cosmological-scale force law embedded in the multipole power spectra of redshift-space distortions. As an example, we obtain an upper limit on the strength of the conformal coupling to matter in the cubic Galileon model, giving $|1/M|\lesssim 200/M_{\mathrm{P}}$. This allows the fifth-force to be stronger than gravity, but is consistent with zero coupling.

We present a systematic analysis of the dynamics of flat Friedmann-Lemaître-Robertson-Walker cosmological models with radiation and dust matter in generalized teleparallel $f(T)$ gravity. We show that the cosmological dynamics of this model are fully described by a function $W(H)$ of the Hubble parameter, which is constructed from the function $f(T)$. After reducing the phase space to two dimensions, we derive the conditions on $W(H)$ for the occurrence of de Sitter fixed points, accelerated expansion, crossing the phantom divide, and finite time singularities. Depending on the model parameters, it is possible to have a bounce (from contraction to expansion) or a turnaround (from expansion to contraction), but cyclic or oscillating scenarios are prohibited. As an illustration of the formalism we consider power law $f(T)=T+\alpha (-T{)}^n$ models, and show that these allow only one period of acceleration and no phantom divide crossing.

We analyze the prospects for resonant di-Higgs production searches at the LHC in the $b\overline{b}{W}^{+}{W}^{-}$ ($W^{+}\to {\ell }^{+}{\nu }_{\ell }$, $W^{-}\to {\ell }^{-}{\overline{\nu }}_{\ell }$) channel, as a probe of the nature of the electroweak phase transition in Higgs portal extensions of the Standard Model. In order to maximize the sensitivity in this final state, we develop a new algorithm for the reconstruction of the $b\overline{b}{W}^{+}{W}^{-}$ invariant mass in the presence of neutrinos from the $W$ decays, building from a technique developed for the reconstruction of resonances decaying to ${\tau }^{+}{\tau }^{-}$ pairs. We show that resonant di-Higgs production in the $b\overline{b}{W}^{+}{W}^{-}$ channel could be a competitive probe of the electroweak phase transition already with the data sets to be collected by the CMS and ATLAS experiments in run 2 of the LHC. The increase in sensitivity with larger amounts of data accumulated during the high-luminosity LHC phase can be sufficient to enable a potential discovery of the resonant di-Higgs production in this channel.

We investigate the spin-dependent (naive) T-odd fragmentation function $D_{1T}^{\perp }$, which can provide an explanation on the transverse polarization of the ${\mathrm{\Lambda }}^0$ hyperon produced in an unpolarized process. We calculate $D_{1T}^{\perp }$ for light flavors in the spectator diquark model, with a Gaussian form factor at the hyperon-quark-diquark vertex. We include in the calculation both the scalar diquark and axial-vector diquark spectators. We determine the values of the model parameters by fitting the unpolarized fragmentation function $D_1^{\mathrm{\Lambda }}$ to the parametrization for $D_1^{\mathrm{\Lambda }}$ by de Florian, Stratmann and Vogelsang. In addition, we compute the longitudinal polarization fragmentation function $G_1^{\mathrm{\Lambda }}$ and compare it with the known parametrization of $G_1^{\mathrm{\Lambda }}$. We also estimate the transverse polarizations of $\mathrm{\Lambda }$ production, in both semi-inclusive deep inelastic scattering and single inclusive $e^{+}{e}^{-}$ annihilation.

We propose to constrain the gluon Wigner distribution in the nucleon by studying the exclusive diffractive dijet production process in ultraperipheral proton-nucleus collisions (UPCs) at the RHIC and the LHC. Compared to the previous proposal in Ref. [Y. Hatta, B. W. Xiao, and F. Yuan, Phys. Rev. Lett. 116, 202301 (2016).] to study the same observable in lepton-nucleon scattering, the use of UPCs has a few advantages: not only is the cross section larger, but the extraction of the Wigner distribution from the data also becomes simpler, including its elliptic angular dependence. We compute the corresponding cross section and evaluate the coefficients using models which include the gluon saturation effects. A potential for the measurements of the Wigner distribution at current and future experimental facilities is also discussed.