We examine the real-time dynamics of a system of one or more black holes interacting with long wavelength gravitational fields. We find that the (classical) renormalizability of the effective field theory that describes this system necessitates the introduction of a time dependent mass counterterm, and consequently the mass parameter must be promoted to a dynamical degree of freedom. To track the time evolution of this dynamical mass, we compute the expectation value of the energy-momentum tensor within the in-in formalism, and fix the time dependence by imposing energy-momentum conservation. Mass renormalization induces logarithmic ultraviolet divergences at quadratic order in the gravitational coupling, leading to a new time-dependent renormalization group (RG) equation for the mass parameter. We solve this RG equation and use the result to predict heretofore unknown high order logarithms in the energy distribution of gravitational radiation emitted from the system.

Transfer of quantum information from the interior of a black hole to its atmosphere is described, in models based on effective field theory. This description illustrates that such transfer need not be violent to the semiclassical geometry or to infalling observers, and in particular can avoid producing a singular horizon or “firewall”. One can specifically quantify the rate of information transfer and show that a rate necessary to unitarize black hole evaporation produces a relatively mild modification to the stress tensor near the horizon. In an exterior description of the transfer, the new interactions responsible for it are approximated by “effective sources” acting on fields in the black hole atmosphere. If the necessary interactions couple to general modes in the black hole atmosphere, one also finds a straightforward mechanism for information transfer rates to increase when a black hole is mined, avoiding paradoxical behavior. Correspondence limits are discussed, in the presence of such new interactions, for both small black holes and large ones; the near-horizon description of the latter is approximately that of Rindler space.

In this paper we present a data analysis approach applicable to the potential saddle-point fly-by mission extension of LISA Pathfinder (LPF). At the peak of its sensitivity, LPF will sample the gravitational field in our Solar System with a precision of several $\mathrm{fm}/{\mathrm{s}}^2/\sqrt{\mathrm{Hz}}$ at frequencies around 1 mHz. Such an accurate accelerometer will allow us to test alternative theories of gravity that predict deviations from Newtonian dynamics in the nonrelativistic limit. As an example, we consider the case of the Tensor-Vector-Scalar (TeVeS) theory of gravity and calculate, within the nonrelativistic limit of this theory, the signals that anomalous tidal stresses generate in LPF. We study the parameter space of these signals and divide it into two subgroups, one related to the mission parameters and the other to the theory parameters that are determined by the gravity model. We investigate how the mission parameters affect the signal detectability concluding that these parameters can be determined with the sufficient precision from the navigation of the spacecraft and fixed during our analysis. Further, we apply Bayesian parameter estimation and determine the accuracy to which the gravity theory parameters may be inferred. We evaluate the portion of parameter space that may be eliminated in case of no signal detection and estimate the detectability of signals as a function of parameter space location. We also perform a first investigation of non-Gaussian “noise glitches” that may occur in the data. The analysis we develop is universal and may be applied to anomalous tidal stress induced signals predicted by any theory of gravity.

We point out that violation of Lorentz invariance affects the interaction of high-energy photons with the Earth’s atmosphere and magnetic field. In a certain parameter region this interaction becomes suppressed and the photons escape observation, passing through the atmosphere without producing air showers. We argue that a detection of photon-induced air showers with energies above $10^{19}\mathrm{eV}$, implying the absence of suppression as well as the absence of photon decay, will put tight double-sided limits on Lorentz violation in the sector of quantum electrodynamics. These constraints will be by several orders of magnitude stronger than the existing ones and will be robust against any assumptions about the astrophysical origin of the detected photons.

Direct photons play an important role as electromagnetic probes from the quark-gluon plasma (QGP) which occurs during ultrarelativistic heavy-ion collisions. In this context, it is of particular interest how the finite lifetime of the QGP affects the resulting photon production. Earlier investigations on this question were accompanied by a divergent contribution from the vacuum polarization and by the remaining contributions not being integrable in the ultraviolet (UV) domain. In this work, we provide a different approach in which we do not consider the photon number density at finite times, but for free asymptotic states obtained by switching the electromagnetic interaction according to the Gell-Mann and Low theorem. This procedure eliminates a possible unphysical contribution from the vacuum polarization and, moreover, renders the photon number density UV integrable. It is emphasized that the consideration of free asymptotic states is, indeed, crucial to obtain such physically reasonable results.

We study the general properties of axially symmetric dissipative configurations under the shear-free condition. The link between the magnetic part of the Weyl tensor and the vorticity is clearly exhibited, as well as the role of the dissipative fluxes. As a particular case, we examine the geodesic fluid. In this case, the magnetic part of the Weyl tensor always vanishes, suggesting that no gravitational radiation is produced during the evolution. In addition, for the geodesic case, in the absence of dissipation, the system evolves towards a Friedmann-Roberston-Walker spacetime if the expansion scalar is positive.

The spin measurement of black holes has important implications in physics and astrophysics. Regardless of the specific technique to estimate the black hole spin, all the current approaches assume that the spacetime geometry around the compact object is exactly described by the Kerr solution. This is clearly an approximation, because the Kerr metric is a stationary solution of the vacuum Einstein equations. In this paper, we estimate the effect of a massive accretion disk in the measurement of the black hole spin with a simple analytical model. For typical accretion disks, the mass of the disk is completely negligible, even for future more accurate measurements. However, for systems with very massive disks the effect may not be ignored.

We compute the one-loop correction to the probe D3-brane action in $Ad{S}_5\times S^5$ expanded around the classical Drukker–Fiol solution ending on a circle at the boundary. It is essentially the logarithm of the one-loop partition function of an Abelian $\mathcal{N}=4$ vector multiplet in $Ad{S}_2\times S^2$ geometry. This one-loop correction should be describing the subleading $1/N$ term in the expectation value of circular Wilson loop in the totally symmetric rank $k$ representation in $SU(N)$ supersymmetric Yang-Mills theory at strong coupling. In the limit $1\ll k\ll N$ when the circular Wilson loop expectation values for the symmetric representation and for the product of $k$ fundamental representations are expected to match, we find that this one-loop D3-brane correction agrees with the gauge theory result for the $k$-fundamental case.

We revisit the effective low-energy dynamics of the volume modulus in warped flux compactifications with anti-D3-branes in order to analyze the prospects for metastable de Sitter vacua and brane inflation along the lines of KKLT/KKLMMT. At the level of the ten-dimensional supergravity solution, antibranes in flux backgrounds with opposite charge are known to source singular terms in the energy densities of the bulk fluxes, which led to a debate on the consistency of such constructions in string theory. A straightforward yet nontrivial check of the singular solution is to verify that its dimensional reduction in the large-volume limit reproduces the four-dimensional low-energy dynamics expected from known results where the antibranes are treated as a probe. Taking into account the antibrane backreaction in the effective scalar potential, we find that both the volume scaling and the coefficient of the antibrane uplift term are in exact agreement with the probe potential if the singular fluxes satisfy a certain near-brane boundary condition. This condition can be tested explicitly and may thus help to decide whether flux singularities should be interpreted as pathological or benign features of flux compactifications with antibranes. Throughout the paper, we also comment on a number of subtleties related to the proper definition of warped effective field theory with antibranes.

The phase transition and jet quenching parameter $\widehat{q}$ are investigated in the framework of the dynamical holographic QCD model. We find that both the trace anomaly and the ratio of the jet quenching parameter over cubic temperature $\widehat{q}/T^3$ show a peak around the critical temperature $T_c$, and the ratio of the jet quenching parameter over entropy density $\widehat{q}/s$ sharply rises at $T_c$. This indicates that the jet quenching parameter can characterize the phase transition. The effect of the jet quenching parameter enhancement around the phase transition on the nuclear modification factor $R_{AA}$ and elliptic flow $v_2$ are also analyzed, and we find that the temperature-dependent jet quenching parameter from the dynamical holographic QCD model can considerably improve the description of jet quenching azimuthal anisotropy as compared with the conformal case.

We consider the Schrödinger equation for a relativistic point particle in an external one-dimensional $\delta$-function potential. Using dimensional regularization, we investigate both bound and scattering states, and we obtain results that are consistent with the abstract mathematical theory of self-adjoint extensions of the pseudodifferential operator $H=\sqrt{p^2+m^2}$. Interestingly, this relatively simple system is asymptotically free. In the massless limit, it undergoes dimensional transmutation and it possesses an infrared conformal fixed point. Thus it can be used to illustrate nontrivial concepts of quantum field theory in the simpler framework of relativistic quantum mechanics.

This is the eighth paper in the series devoted to the systematic study of effective theories. Below, I discuss the renormalization of the one-loop two-leg functions in multicomponent effective scalar theory. It is shown that only a part of numerous contributions that appear in the general expression for a two-leg graph can be considered as the true self-energy function. This part is completely fixed by the values of minimal coupling constants; it is the only one that should be taken into account in the conventional process of the summation of Dyson’s chain that results in explicit expression for the full propagator. The other parts provide the well-defined finite corrections for the graphs with the number of legs $n>2$. It is also shown that there is no need to attract the renormalization prescriptions for the higher derivatives of the two-leg function on the mass shell; the requirements of finiteness and diagonability turn out to be quite sufficient.

In this paper noncommutative gravity is constructed as a gauge theory of the noncommutative $SO(2,3{)}_{\star }$ group, while the noncommutativity is canonical (constant). The Seiberg-Witten map is used to express noncommutative fields in terms of the corresponding commutative fields. The commutative limit of the model is the Einstein-Hilbert action with the cosmological constant term and the topological Gauss-Bonnet term. We calculate the second order correction to this model and obtain terms that are of zeroth to fourth power in the curvature tensor and torsion. Trying to relate our results with $f(R)$ and $f(T)$ models, we analyze different limits of our model. In the limit of big cosmological constant and vanishing torsion we obtain an $x$-dependent correction to the cosmological constant; i.e. noncommutativity leads to an $x$-dependent cosmological constant. We also discuss the limit of small cosmological constant and vanishing torsion and the teleparallel limit.

We examine a quantum group extension of the standard model. The field operators of the extended theory are obtained by replacing the field operators $\mathrm{\Psi }$ of the standard model by $\widehat{\mathrm{\Psi }}{\mathrm{D}}_{m{m}^{\prime }}^j$, where ${\mathrm{D}}_{m{m}^{\prime }}^j$ are elements of a representation of the quantum algebra SLq(2), which is also the knot algebra. The ${\mathrm{D}}_{m{m}^{\prime }}^j$ lie in this algebra and carry the new degrees of freedom of the field quanta. The ${\mathrm{D}}_{m{m}^{\prime }}^j$ are restricted jointly by empirical constraints and by a postulated correspondence with classical knots. The elementary fermions are described by elements of the trefoil ($j=\frac{3}{2}$) representation and the weak vector bosons by elements of the ditrefoil ($j=3$) representation. The adjoint ($j=1$) and fundamental ($j=\frac{1}{2}$) representations define hypothetical bosonic and fermionic preons. All particles described by higher representations may be regarded as composed of the fermionic preons. This preon model unexpectedly agrees in important detail with the Harari-Shupe model. The new Lagrangian, which is invariant under gauge transformations of the SLq(2) algebra, fixes the relative masses of the elementary fermions within the same family. It also introduces form factors that modify the electroweak couplings and provide a parametrization of the Cabbibo-Kobayashi-Maskawa matrix. It is additionally postulated that the preons carry gluon charge and that the fermions, which are three preon systems, are in agreement with the color assignments of the standard model.

Quantum fluctuations or other moments of a state contribute to energy expectation values and can imply interesting physical effects. In quantum cosmology, they turn out to be important for a discussion of density bounds and instabilities of initial-value problems in the presence of signature change in loop-quantized models. This paper provides an effective description of these issues, accompanied by a comparison with existing numerical results and an extension to squeezed states. The comparison confirms that canonical effective methods are well suited for computations of properties of physical states. As a side product, an example is found for a simple state in which quantum fluctuations can cancel holonomy modifications of loop quantum cosmology.

We characterize and present the details of the follow-up method used on the most significant outliers of the Hough Einstein@Home all-sky search for continuous gravitational waves [J. Aasi et al Phys. Rev. D 87, 042001 (2013)]. This follow-up method is based on the two-stage approach introduced by [M. Shaltev and R. Prix, Phys. Rev. D 87, 084057 (2013)], consisting of a semicoherent refinement followed by a fully coherent zoom. We quantify the efficiency of the follow-up pipeline using simulated signals in Gaussian noise. This pipeline does not search beyond first-order frequency spin-down, and therefore we also evaluate its robustness against second-order spin-down. We present the details of the Hough Einstein@Home follow-up [J. Aasi et al Phys. Rev. D 87, 042001 (2013)] on three hardware-injected signals and on the eight most significant search outliers of unknown origin.

We present the Riemann and Ricci tensors for a fully general nontwisting and shear-free geometry in arbitrary dimension $D$. This includes both the nonexpanding Kundt and expanding Robinson–Trautman family of spacetimes. As an interesting application of these explicit expressions, we then integrate the Einstein equations and prove a surprising fact that in any $D$ the Robinson–Trautman class does not admit solutions representing gyratonic sources, i.e., a matter field in the form of a null fluid (or particles propagating with the speed of light) with an additional internal spin. Contrary to the closely related Kundt class and $pp$-waves, the corresponding off-diagonal metric components thus do not encode the angular momentum of some gyraton. Instead, we demonstrate that in standard $D=4$ general relativity they directly determine two independent amplitudes of the Robinson–Trautman exact gravitational waves.

We present the complete set of analytical solutions of the geodesic equations in the general five-dimensional Myers-Perry spacetime in terms of the Weierstrass $\wp$, $\zeta$, and $\sigma$ functions. We analyze the underlying polynomials in the polar and radial equations, which depend on the parameters of the metric and the conserved quantities of a test particle, and characterize the motion by their zeros. We exemplify the efficiency of the analytical method on the basis of the explicit construction of test particle orbits and by addressing observables in this spacetime.

We examine the effect of nuclear response functions, as laid out by Fitzpatrick et al. [J. Cosmol. Astropart. Phys. 02 (2013) 004], on dark matter (DM) direct detection in the context of well-motivated UV completions, including electric and magnetic dipoles, anapole, spin-orbit, and pseudoscalar-mediated DM. Together, these encompass five of the six nuclear responses extracted from the nonrelativistic effective theory of Fitzpatrick et al. [J. Cosmol. Astropart. Phys. 02 (2013) 004] (with the sixth difficult to UV complete), with two of the six combinations corresponding to standard spin-independent and spin-dependent responses. For constraints from existing direct detection experiments, we find that only the COUPP constraint, due to its heavy iodine target with large angular momentum and an unpaired spin, and its large energy range sensitivity, is substantially modified by the new responses compared to what would be inferred using the standard form factors to model the energy dependence of the response. For heavy targets such as xenon and germanium, the behavior of the new nuclear responses as recoil energy increases can be substantially different from that of the standard responses, but this has almost no impact on the constraints derived from experiments such as LUX, XENON100, and CDMS since the maximum nuclear recoil energy detected in these experiments is relatively low. We simulate mock data for 80 and 250 GeV DM candidates utilizing the new nuclear responses to highlight how they might affect a putative signal, and find the new responses are most important for highly momentum-suppressed interactions such as the magnetic dipole or pseudoscalar-mediated interaction when the target is relatively heavy (such as xenon and iodine).

We explore a new type of entropic mechanism for generating density perturbations in a contracting phase in which there are two scalar fields but only one has a steep negative potential. This first field dominates the energy density and is the source of the ekpyrotic equation of state. The second field has a negligible potential, but its kinetic energy density is coupled to the first field with a nonlinear sigma-model type interaction. We show that for any ekpyrotic equation of state it is possible to choose the potential and the kinetic coupling such that exactly scale-invariant (or nearly scale-invariant) entropy perturbations are produced. The corresponding background solutions are stable, and the bispectrum of the entropy perturbations vanishes as no non-Gaussianity is produced during the ekpyrotic phase. Hence, the only contribution to non-Gaussianity comes from the nonlinearity of the conversion process during which entropic perturbations are turned into adiabatic ones, resulting in a local non-Gaussianity parameter, $f_{\mathrm{NL}}\sim 5$.