Recently, axionlike particle search has received renewed interest, and several groups have started experiments. In this paper, we present the final results of our experiment on photon-axion oscillations in the presence of a magnetic field, which took place at the Laboratoire pour l’Utilisation des Lasers Intenses, Palaiseau, France. Our null measurement allowed us to exclude the existence of axions with inverse coupling constant $M>9.\times {10}^5\mathrm{GeV}$ for low axion masses and to improve the preceding Brookhaven-Fermilab-Rochester-Trieste (BFRT) Collaboration limits by a factor of 3 or more for axion masses $1.1<m_a<2.6\mathrm{meV}$. We also show that our experimental results improve the existing limits on the parameters of a low mass hidden-sector boson usually dubbed “paraphoton” because of its similarity with the usual photon. We detail our apparatus which is based on the “light shining through the wall” technique. We compare our results to other existing ones.

We calculate the prompt neutrino flux from atmospheric charm production by cosmic rays, using the dipole picture in a perturbative QCD framework, which incorporates the parton saturation effects present at high energies. We compare our results with the next-to-leading-order perturbative QCD result and find that saturation effects are large for neutrino energies above ${10}^6\mathrm{GeV}$, leading to a substantial suppression of the prompt neutrino flux. We comment on the range of prompt neutrino fluxes due to theoretical uncertainties.

We consider extremal black hole solutions to the vacuum Einstein equations in dimensions greater than five. We prove that the near-horizon geometry of any such black hole must possess an $SO(2,1)$ symmetry in a special case where one has an enhanced rotational symmetry group. We construct examples of vacuum near-horizon geometries using the extremal Myers-Perry black holes and boosted Myers-Perry strings. The latter lead to near-horizon geometries of black ring topology, which in odd spacetime dimensions have the correct number of rotational symmetries to describe an asymptotically flat black object. We argue that a subset of these correspond to the near-horizon limit of asymptotically flat extremal black rings. Using this identification we provide a conjecture for the exact “phase diagram” of extremal vacuum black rings with a connected horizon in odd spacetime dimensions greater than five.

We discuss color transparency in the nuclear QCD context from the perspective of pre- and post-selected ensembles. We show that the small size of the hadronic states can be explained by the peculiar “force of post-selection,” in contrast to the more standard explanation based on external forces.

We consider the branching ratio and the $CP$ asymmetries in $B\to f_0(980)K_S$ decay to the end of determining the deviation of the time-dependent $CP$ asymmetry from $\sin (2\beta )$, $\Delta S_{f_0{K}_S}\equiv -{\eta }_{f_0{K}_S}{S}_{f_0{K}_S}-\sin (2\beta )$, arising from standard model physics. We obtain $\Delta S_{f_0{K}_S}$ within the context of the QCD factorization framework for the $B\to f_0(980)K_S$ decay amplitudes assuming the $f_0(980)$ is a $q\overline{q}$ state and employing a random scan over the theoretical parameter space to assess the possible range in $\Delta S_{f_0{K}_S}$. Imposing the value of the experimental branching ratio within $1\sigma$ and $3\sigma$, respectively, of its central value as a constraint, we find the range of $\Delta S_{f_0{K}_S}$ to be [0.018, 0.033] for a scan in which the parameters are allowed to vary within $1\sigma$ of their central values and the range $[-0.019,0.064]$ for a scan in which the parameters vary within $3\sigma$ of their central values.

We study the constraints on the contribution of new physics in the form of scalar/pseudoscalar operators to the average forward-backward asymmetry $⟨A_{\mathrm{FB}}⟩$ of muons in $B\to K{\mu }^{+}{\mu }^{-}$ and the longitudinal polarization asymmetry $A_{\mathrm{LP}}$ of muons in $B_s\to {\mu }^{+}{\mu }^{-}$. We find that the maximum possible value of $⟨A_{\mathrm{FB}}⟩$ allowed by the present upper bound on $B(B_s\to {\mu }^{+}{\mu }^{-})$ is about 1% at 95% C.L. and hence will be very difficult to measure. On the other hand, the present bound on $B(B_s\to {\mu }^{+}{\mu }^{-})$ fails to put any constraints on $A_{\mathrm{LP}}$, which can be as high as 100% even if $B(B_s\to {\mu }^{+}{\mu }^{-})$ is close to its standard model prediction. The measurement of $A_{\mathrm{LP}}$ will be a direct evidence for an extended Higgs sector, and combined with the branching ratio $B(B_s\to {\mu }^{+}{\mu }^{-})$ it can even separate the new physics scalar and pseudoscalar contributions.

Intrigued by a recent Belle result for a large direct $CP$ asymmetry in $B^0\to D^{+}{D}^{-}$, we study the effects of a $\overline{b}\to \overline{u}u\overline{d}$ quark transition by combining the asymmetry information with rates and asymmetries in isospin-related decays. Arguing for a hierarchy among several contributions to these decays, including an exchange amplitude which we estimate, we present tests for factorization of the leading terms, and obtain an upper bound on the ratio of $\overline{b}\to \overline{u}u\overline{d}$ and $\overline{b}\to \overline{c}c\overline{d}$ amplitudes. We prove an approximate $\Delta I=1/2$ amplitude relation for $B\to D\overline{D}$, and an approximate equality between $CP$ asymmetries in $B^0\to D^{+}{D}^{-}$ and $B^{+}\to D^{+}{\overline{D}}^0$. Violations of these relations by Belle measurements, at $1.8\sigma$ and $3.6\sigma$ respectively, if confirmed, would indicate a possible new physics contribution in $\overline{b}\to \overline{u}u\overline{d}$. Applying flavor SU(3), we extend this study to a total of ten processes, including $\Delta S=0$ decays involving final $D_s$ and initial $B_s$ mesons, and $\Delta S=1$ decays of $B$ and $B_s$ mesons into pairs of charmed pseudoscalar mesons. The decays $B_s\to D\overline{D}$ provide useful information about a small exchange amplitude, responsible for a decay rate difference between $B^{+}\to D^{+}{\overline{D}}^0$ and $B^0\to D^{+}{D}^{-}$. A method for determining the weak phase $\gamma$, based on $CP$ asymmetries in $B^0(t)\to D^{+}{D}^{-}$ and the decay rate for $B_s\to D_s^{+}{D}_s^{-}$ or $B^{+(0)}\to D_s^{+}{\overline{D}}^0(D^{-})$, is shown to involve high sensitivity to SU(3) breaking.

Using data taken with the CLEO-c detector at the Cornell Electron Storage Ring, we have investigated the direct-photon momentum spectrum in the decay $J/\psi (1\mathrm{S})\to \gamma gg$, via the “tagged” process: $e^{+}{e}^{-}\to \psi (2\mathrm{S})$; $\psi (2\mathrm{S})\to J/\psi {\pi }^{+}{\pi }^{-}$; $J/\psi \to \gamma +X$. Including contributions from two-body radiative decay processes, we find the ratio of the inclusive direct-photon branching fraction to that of the dominant three-gluon branching fraction [$R_{\gamma }=B(gg\gamma )/B(ggg)$] to be $R_{\gamma }=0.137\pm 0.001\pm 0.016\pm 0.004$, where the errors shown are statistical, systematic, and the model-dependent uncertainty related to the extrapolation to zero photon energy. The shape of the scaled photon energy spectrum in $J/\psi \to gg\gamma$ is observed to be very similar to that of ${\rm Y}\to gg\gamma$. The $R_{\gamma }$ value obtained is roughly consistent with that expected by a simple quark-charge scaling [$R_{\gamma }\sim (q_c/q_b{)}^2$] of the value determined at the ${\rm Y}(1\mathrm{S})$, but somewhat higher than the value expected from the running of the strong coupling constant.

We consider different types of fractional branes on a ${\mathbb{Z}}_2$ orbifold of the conifold and analyze in detail the corresponding gauge/gravity duality. The gauge theory possesses a rich and varied dynamics, both in the UV and in the IR. We find the dual supergravity solution, which contains both untwisted and twisted 3-form fluxes, related to what are known as deformation and $\mathcal{N}=2$ fractional branes, respectively. We analyze the resulting renormalization group flow from the supergravity perspective, by developing an algorithm to easily extract it. We find hints of a generalization of the familiar cascade of Seiberg dualities due to a nontrivial interplay between the different types of fractional branes. We finally consider the IR behavior in several limits, where the dominant effective dynamics is either confining in a Coulomb phase or runaway, and discuss the resolution of singularities in the dual geometric background.

We study the $\cos 2\varphi$ azimuthal asymmetry in unpolarized semi-inclusive DIS, taking into account both the perturbative contribution (gluon emission and splitting) and the nonperturbative effects arising from intrinsic transverse motion and transverse spin of quarks. In particular we explore the possibility to extract from $⟨\cos 2\varphi ⟩$ some information about the Boer-Mulders function $h_1^{\perp }$, which represents a transverse-polarization asymmetry of quarks inside an unpolarized hadron. Predictions are presented for the HERMES, COMPASS and JLab kinematics, where $⟨\cos 2\varphi ⟩$ is dominated by the kinematical higher-twist contribution, and turns to be of order of a few percent. We show that under reasonable assumptions a larger asymmetry in ${\pi }^{-}$ production, compared to ${\pi }^{+}$ production, would represent a signature of the Boer-Mulders effect.

We investigate the vacuum polarization effects associated with a charged massless spin-$1/2$ field in a higher-dimensional space-time, induced by a composite topological defect. The defect is constituted by a global monopole living on a three brane and two-dimensional conical space transverse to the latter. In addition, we assume the presence of an extra magnetic flux along the core of the conical space. The heat kernel and the Feynman Green function are presented in the form of a sum of two terms. The first one corresponds to the contribution coming from the bulk with global monopole in the absence of conical structure of the orthogonal two space, and the second one is induced by this structure and the magnetic flux. We explicitly evaluate the part in the vacuum expectation value of the energy-momentum tensor induced by the flux carrying conical structure. As in pure cosmic string geometries, only the fractional part of the ratio of the magnetic flux to flux quantum leads to nontrivial effects. The vacuum energy-momentum tensor is an even function of this parameter. We show that for strong gravitational fields corresponding to large values of the solid angle deficit, the effects induced by the conical structure and flux are exponentially suppressed.

We study monopole solutions of the quantum exact low-energy effective $N=2$ super Yang-Mills theories of Seiberg and Witten. We find a first-order differential equation for the spatial dependence of the moduli and show that it can be interpreted as an attractor equation. Numerically integrating this equation, we try to address the question of what happens when one approaches the quantum core of the monopole where the low-energy effective theory breaks down or, alternatively, where there are modified monopole solutions that do not have a strongly coupled quantum core so that one may trust the solution not only asymptotically.

We study quenched $SU(N)$ gauge theories with fermions in the two-index symmetric, antisymmetric and the adjoint representations. Our main motivation is to check whether at large number of colors those theories become nonperturbatively equivalent. We prove the equivalence assuming that the charge-conjugation symmetry is not broken in pure Yang-Mills theory. We then carry out a quenched lattice simulation of the quark condensate in the symmetric, antisymmetric and the adjoint representations for $SU(2)$, $SU(3)$, $SU(4)$, $SU(6)$, and $SU(8)$. We show that the data support the equivalence and discuss the size of subleading corrections.

The calculation of the real part of a quasiparticle dispersion relation at next-to-leading order in the hard thermal loop effective theory is a very difficult problem. Even though the hard thermal loop effective theory is almost 20 years old, there is only one next-to-leading order calculation of the real part of a quasiparticle dispersion relation in the literature [H. Schulz, Nucl. Phys. B413, 353 (1994)]. In this paper, we calculate the fermion mass in QED and QCD at next-to-leading order. For QED the result is $M=eT/\sqrt{8}(1-(1.427\pm 0.02)e/4\pi )$ and for QCD with $N_f=2$ and $N_c=3$ we obtain $M=gT/\sqrt{6}(1+(1.867\pm 0.02)g/4\pi )$.

This paper is committed to calculations near a type of future singularity driven by phantom energy. At the singularities considered, the scale factor remains finite but its derivative diverges. The general behavior of barotropic phantom energy producing this singularity is calculated under the assumption that near the singularity such fluid is the dominant contributor. We use the semiclassical formula for renormalized stress tensors of conformally invariant fields in conformally flat spacetimes and analyze the softening/enhancing of the singularity due to quantum vacuum contributions. This dynamical analysis is then compared to results from thermodynamical considerations. In both cases, the vacuum states of quantized scalar and spinor fields strengthen the accelerating expansion near the singularity whereas the vacuum states of vector fields weaken it.

We review Gordon’s optical metric and the transport equations for the amplitude and polarization of a geometrical optics wave traveling in a gravity field. We apply the theory to the Friedmann-Lemaître-Robertson-Walker cosmologies by associating a refraction index with the cosmic fluid. We then derive an expression for the accumulated effect of a refraction index on the distance-redshift relations and fit the Hubble curve of current supernova observations with a nonaccelerating cosmological model. We also show that some observational effects caused by inhomogeneities, e.g., the Sachs-Wolfe effect, can be interpreted as being caused by an effective index of refraction, and hence this theory could extend to other speed of light communications such as gravitational radiation and neutrino fluxes.

The effective-one-body (EOB) formalism contains several flexibility parameters, notably $a_5$, $v_{\mathrm{pole}}$, and ${\overline{a}}_{\mathrm{RR}}$. We show here how to jointly constrain the values of these parameters by simultaneously best-fitting the EOB waveform to two, independent, numerical relativity (NR) simulations of inspiralling and/or coalescing binary black-hole systems: published Caltech-Cornell inspiral data (considered for gravitational wave frequencies $M\omega \le 0.1$) on one side, and newly computed coalescence data on the other side. The resulting, approximately unique, “best-fit” EOB waveform is then shown to exhibit excellent agreement with NR coalescence data for several mass ratios. The dephasing between this best-fit EOB waveform and published Caltech-Cornell inspiral data is found to vary between $-0.0014$ and $+0.0008$ radians over a time span of $\sim 2464M$ up to gravitational wave frequency $M\omega =0.1$, and between $+0.0013$ and $-0.0185$ over a time span of $96M$ after $M\omega =0.1$ up to $M\omega =0.1565$. The dephasings between EOB and the new coalescence data are found to be smaller than: (i) $\pm 0.025$ radians over a time span of $730M$ (11 cycles) up to merger, in the equal-mass case, and (ii) $\pm 0.05$ radians over a time span of about $950M$ (17 cycles) up to merger in the $2:1$ mass-ratio case. These new results corroborate the aptitude of the EOB formalism to provide accurate representations of general relativistic waveforms, which are needed by currently operating gravitational wave detectors.

For a class of Friedmann-Robertson-Walker–type string solutions with compact hyperbolic spatial slices formulated in the critical dimension, we find the world-sheet conformal field theory which involves the linear dilaton and the Wess-Zumino-Witten–type model with a compact hyperbolic target space. By analyzing the infrared spectrum, we conclude that the theory is actually supercritical due to modular invariance. Thus, taking into account previous results, we conclude that all simple nontrivial string cosmological solutions are in fact supercritical. In addition, we discuss the relationship of this background with the supercritical string cosmology.

Free scalar field theory on 2-dimensional flat spacetime, cast in diffeomorphism invariant guise by treating the inertial coordinates of the spacetime as dynamical variables, is quantized using loop quantum gravity (LQG) type “polymer” representations for the matter field and the inertial variables. The quantum constraints are solved via group averaging techniques and, analogous to the case of spatial geometry in LQG, the smooth (flat) spacetime geometry is replaced by a discrete quantum structure. An overcomplete set of Dirac observables, consisting of (a) (exponentials of) the standard free scalar field creation-annihilation modes and (b) canonical transformations corresponding to conformal isometries, are represented as operators on the physical Hilbert space. None of these constructions suffer from any of the “triangulation”-dependent choices which arise in treatments of LQG. In contrast to the standard Fock quantization, the non-Fock nature of the representation ensures that the group of conformal isometries as well as that of the gauge transformations generated by the constraints are represented in an anomaly free manner. Semiclassical states can be analyzed at the gauge invariant level. It is shown that “physical weaves” necessarily underlie such states and that such states display semiclassicality with respect to, at most, a countable subset of the (uncountably large) set of observables of type (a). The model thus offers a fertile testing ground for proposed definitions of quantum dynamics as well as semiclassical states in LQG.

We point out that the results by Brandenberger et al. [Phys. Rev. D 77, 083502 (2008)] that the geometry around the straight cosmic strings with stationary junctions is flat to linear order in the string tension can be immediately extended to any order.