We present the details of a model in general relativity of a small charged black hole moving in an external gravitational and electromagnetic field. The importance of our model lies in the fact that we can derive the equations of motion of the black hole from the Einstein-Maxwell vacuum field equations without encountering infinities. The key assumptions which we base our results upon are that (a) the black hole is isolated and (b) near the black hole the wave fronts of the radiation generated by its motion are smoothly deformed spheres. The equations of motion which emerge fit the pattern of the original DeWitt and Brehme equations of motion (after they “renormalize”). Our calculations are carried out in a coordinate system in which the null hypersurface histories of the wave fronts can be specified in a simple way, with the result that we obtain a new explicit form, particular to our model, for the well-known “tail term” in the equations of motion.

We investigate extremal dyon black holes in the Einstein-Maxwell-dilaton theory with higher curvature corrections in the form of the Gauss-Bonnet density coupled to the dilaton. In the same theory without the Gauss-Bonnet term the extremal dyon solutions exist only for discrete values of the dilaton coupling constant $a$. We show that the Gauss-Bonnet term acts as a dyon hair tonic enlarging the allowed values of $a$ to continuous domains in the plane $(a,q_m)$ where $q_m$ is the magnetic charge. In the limit of the vanishing curvature coupling (a large magnetic charge) the dyon solutions obtained tend to the Reissner-Nordström solution but not to the extremal dyons of the Einstein-Maxwell-dilaton theory. Both solutions have the same dependence of the horizon radius in terms of charges. The entropy of new dyonic black holes interpolates between the Bekenstein-Hawking value in the limit of the large magnetic charge (equivalent to the vanishing Gauss-Bonnet coupling) and twice this value for the vanishing magnetic charge. Although an expression for the entropy can be obtained analytically using purely local near-horizon solutions, its interpretation as the black hole entropy is legitimate only once the global black hole solution is known to exist, and we obtain numerically the corresponding conditions on the parameters. Thus, a purely local analysis is insufficient to fully understand the entropy of the curvature-corrected black holes. We also find dyon solutions which are not asymptotically flat, but approach the linear dilaton background at infinity. They describe magnetic black holes on the electric linear dilaton background.

Distances in cosmology are usually inferred from observed redshifts—an estimate that is dependent on the local peculiar motion—giving a distorted view of the three-dimensional structure and affecting basic observables such as the correlation function and power spectrum. We calculate the full nonlinear redshift-space power spectrum for Gaussian fields, giving results for both the standard flat-sky approximation and the directly observable angular correlation function and angular power spectrum $C_l(z,z^{\prime })$. Coupling between large and small-scale modes boosts the power on small scales when the perturbations are small. On larger scales power is slightly suppressed by the velocities perturbations on smaller scales. The analysis is general, but we comment specifically on the implications for future high-redshift observations and show that the nonlinear spectrum has significantly more complicated angular structure than in linear theory. We comment on the implications for using the angular structure to separate cosmological and astrophysical components of 21 cm observations.

The potential use of the redshifted 21 cm line from neutral hydrogen for probing the epoch of reionization is motivating the construction of several low-frequency interferometers. There is also much interest in the possibility of constraining the initial conditions from inflation and the nature of the dark matter and dark energy by probing the power spectrum of density perturbations in three dimensions and on smaller scales than probed by the microwave background anisotropies. Theoretical understanding of the 21 cm signal has been fragmented into different regimes of physical interest. In this paper, we make the first attempt to describe the full redshift evolution of the 21 cm signal between $0<z<300$. We include contributions to the 21 cm signal from fluctuations in the gas density, temperature, and neutral fraction, as well as the $\mathrm{Ly}\alpha$ flux, and allow for a post-reionization signal from damped $\mathrm{Ly}\alpha$ systems. Our comprehensive analysis provides a useful foundation for optimizing the design of future arrays whose goal is to separate the particle physics from the astrophysics, either by probing the peculiar velocity distortion of the 21 cm power spectrum, or by extending the 21 cm horizon to $z\gtrsim 25$ before the first galaxies had formed, or to $z\lesssim 6$ when the residual pockets of hydrogen trace large-scale structure.

We develop velocity-dependent models describing the evolution of string networks that involve several types of interacting strings, each with a different tension. These incorporate the formation of Y-type junctions with links stretching between colliding strings, while always ensuring energy conservation. These models can be used to describe network evolution for non-Abelian strings as well as cosmic superstrings. The application to $Z_N$ strings in which interactions are topologically constrained, demonstrates that a scaling regime is generally reached which involves a hierarchy of string densities with the lightest most abundant. We also study hybrid networks of cosmic superstrings, where energetic considerations are more important in determining interaction outcomes. We again find that networks tend towards scaling, with the three lightest network components being dominant and having comparable number densities, while the heavier string states are suppressed. A more quantitative analysis depends on the precise calculation of the string interaction matrix using the underlying string or field theory. Nevertheless, these results provide further evidence that the presence of junctions in a string network does not obstruct scaling.

New bounds on long-range parity violation in gravitation are reported from inconclusive searches of parity violating energy differences (PVED) in chiral molecules. In particular, it is found that Leitner-Okubo-Hari Dass’s ${\alpha }_2$ (or $A_2$) parameter is constrained by current experimental searches of PVED between molecular enantiomers. The possibility of constraining other parameters which parametrize the strength of contact parity violation in gravity, as well as other long-range parity violating potentials will be briefly commented.

We present a full calculation of the amplitudes for $B_{d[s]}\to \gamma \gamma$ in a simple Appelquist-Cheng-Dobrescu model that extends an incomplete one in a previous paper. We find cancellations between the contributions from different Kaluza-Klein towers and a small decrease relative to the standard model predictions. It is conjectured that radiative QCD corrections might actually lead to an enhancement in the branching ratios and $CP$ asymmetries, but no more than modest ones.

Electromagnetic resonant cavities form the basis of many tests of Lorentz invariance involving photons. The effects of some forms of Lorentz violation scale with cavity size. We investigate possible signals of violations in the naturally occurring resonances formed in the Earth-ionosphere cavity. Comparison with observed resonances places the first terrestrial constraints on coefficients associated with dimension-three Lorentz-violating operators at the level of ${10}^{-20}\mathrm{GeV}$.

We calculate the thermal evolution of $\pi \mathrm{\text{−}}\pi$ scattering lengths, in the framework of the Nambu–Jona-Lasinio model. The thermal corrections were calculated at the one-loop level using thermofield dynamics. We present also results for the pion thermal mass. Our procedure implies the modeling of a propagating scalar meson as a resumation of chains of quark bubbles, which is presented explicitly. We compare our results with previous analysis of this problem in the framework of different theoretical approaches.

Recent data on $B$ meson mixings and decays are, in general, in accord with the standard model expectations, except showing a few hiccups: (i) a large phase in $B_s$ mixing, (ii) a significant difference ($>3.5\sigma$) between $CP$-asymmetries in $B^{\pm }\to {\pi }^0{K}^{\pm }$ and $B_d\to {\pi }^{\mp }{K}^{\pm }$ channels, and (iii) a larger than expected branching ratio in $B_d\to {\pi }^0{\pi }^0$ channel. We show that selective baryon-number violating Yukawa couplings in $R$-parity violating supersymmetry can reconcile all the measurements.

Many extensions of the standard model (SM) generate contributions to flavor changing neutral current (FCNC) processes that must have sufficient flavor suppression to be consistent with experiments, if the new physics (NP) is associated with a scale of a TeV. Here we present a mechanism for suppressing the NP effects to FCNC processes while allowing for new non-SM $CP$ violating phases. We consider the possibility that the source of NP contributions to FCNC processes share the same flavor symmetry underlying the SM source of FCNC processes which are the quark and lepton mass matrices. We call this the principle of shared flavor symmetry. In the flavor symmetric limit, the quark and lepton mixing matrices have fixed forms and there are no NP FCNC processes. In the flavor symmetric limit, we take the quark mixing matrix to be the identity matrix and the lepton mixing matrix to be given by tri-bimaximal mixing. Realistic mixing matrices are obtained by the small breaking of the flavor symmetry. New contributions to FCNC processes arise because of nonuniversal breaking of the flavor symmetry in the quark and lepton mass matrices and the NP sources of FCNC processes. In particular, we will focus on new FCNC effects that arise due to the breaking of flavor symmetry only in the quark and charged lepton mass matrices but not in the NP sector. In this scenario, NP contributions to FCNC processes are linked to the source of flavor symmetry breaking in the quark and charged lepton mass matrices. The breaking of flavor symmetry in the NP sector is assumed to produce FCNC effects that are at most the size of NP FCNC effects due to the breaking of flavor symmetry in the quark and charged lepton mass matrices. To demonstrate the mechanism we use a two Higgs doublet model as an example of beyond the SM physics though one should be able to adapt this mechanism to other models of new physics.

We compare the results of a numerical lattice QCD calculation of the charmonium spectrum with the structure of a general nonrelativistic potential model. To achieve this we form the nonrelativistic reduction of derivative-based fermion bilinear interpolating fields used in lattice QCD calculations and compute their overlap with $c\overline{c}$ meson states at rest constructed in the nonrelativistic quark model, providing a bound-state model interpretation for the lattice data. Essential gluonic components in the bound states, usually called hybrids, are identified by considering interpolating fields that involve the gluonic field-strength tensor and which have zero overlap onto simple $c\overline{c}$ model states.

The gravitational form factor of the pion is evaluated in two chiral quark models and confronted with the recent full-QCD lattice data. We find good agreement for the case of the spectral quark model, which builds in the vector-meson dominance for the charge form factor. We derive a simple relation between the gravitational and electromagnetic form factors, holding in the considered quark models in the chiral limit. The relation implies that the gravitational mean squared radius is half the electromagnetic one. We also analyze higher-order quark generalized form factors of the pion, related to higher moments in the symmetric Bjorken $X$ variable of the generalized parton distribution functions, and discuss their perturbative QCD evolution, which is needed to relate the quark-model predictions to the lattice data. The values of the higher-order quark form factors at $t=0$, computed on the lattice, also agree with our quark-model results within the statistical and method uncertainties.

We study the impact of the full $\mathcal{O}({\alpha }_s)$ QCD and $\mathcal{O}({\alpha }_{\mathrm{ew}})$ electroweak (EW) radiative corrections to the $e^{+}{e}^{-}\to t\overline{t}{Z}^0$ process in the standard model, and investigate the dependence of the lowest-order (LO), one-loop QCD and EW corrected cross sections on colliding energy $\sqrt{s}$. The LO, QCD and EW corrected spectrums of the invariant mass of $t\overline{t}$ pair and the distributions of the transverse momenta of final top quark and $Z^0$ boson are presented. The numerical results show that the one-loop QCD correction enhances the LO cross section, but the EW one-loop correction generally suppresses the LO cross section with our chosen parameters. In the case of $m_H=120\mathrm{GeV}$, the QCD relative corrections can reach 43.16% when $\sqrt{s}=500\mathrm{GeV}$, while the EW relative corrections have the values of $-9.24\%$, $-4.36\%$ and $-5.81\%$, when $\sqrt{s}=500\mathrm{GeV}$, 800 GeV, 1.2 TeV, respectively.

We estimate the production of two meson pairs in high energy photon-photon collisions produced in ultraperipheral collisions at LHC. We show that the study of charge asymmetries may reveal the existence of the perturbative Odderon and discuss the concrete event rates expected at the LHC. Sizable rates and asymmetries are expected in the case of proton-proton collisions and medium values of $\gamma \gamma$ energies $\sqrt{s_{\gamma \gamma }}\approx 20\mathrm{GeV}$. Proton-proton collisions will benefit from a high rate due to a large effective $\gamma \gamma$ luminosity and ion-ion collisions with a somewhat lower rate from the possibility to trigger on ultraperipheral collisions and a reduced background from strong interactions.

We present a tribimaximal lepton mixing scheme where the neutrinoless double beta decay rate has a lower bound which correlates with the ratio $\alpha \equiv \Delta m_{\mathrm{sol}}^2/\Delta m_{\mathrm{atm}}^2$ well determined by current data, as well as with the unknown Majorana $CP$ phase ${\varphi }_{12}$ characterizing the solar neutrino subsystem. For the special value ${\varphi }_{12}=\frac{\pi }{2}$ (opposite $CP$-sign neutrinos) the $\beta {\beta }_{0\nu }$ rate vanishes at tree level when $\Delta m_{\mathrm{sol}}^2/\Delta m_{\mathrm{atm}}^2=3/80$, only allowed at $3\sigma$. For all other cases the rate is nonzero, and lies within current and projected experimental sensitivities close to ${\varphi }_{12}=0$. We suggest two model realizations of this scheme in terms of $A_4\times Z_2$ and $A_4\times Z_4$ flavor symmetries.

We used a torsion pendulum containing $\approx {10}^{23}$ polarized electrons to search new interactions that couple to electron spin. We limit $CP$-violating interactions between the pendulum’s electrons and unpolarized matter in the Earth or the Sun, test for rotation and boost-dependent preferred-frame effects using the Earth’s rotation and velocity with respect to the entire cosmos, and search for exotic velocity-dependent potentials between polarized electrons and unpolarized matter in the Sun and Moon. We find $CP$-violating parameters $|g_{\mathrm{P}}^e{g}_{\mathrm{S}}^N|/(\hslash c)<9.4\times {10}^{-37}$ and $|g_{\mathrm{A}}^e{g}_{\mathrm{V}}^N|/(\hslash c)<1.2\times {10}^{-56}$ for $\lambda >1\mathrm{AU}$. We test for preferred-frame interactions of the form $V=-{\mathit{\sigma }}^e·\mathit{A}$, $V=-B{\mathit{\sigma }}^e·\mathit{v}/c$, or $V=-\sum _{}^{}{\sigma }_i^e{C}_{ij}{v}_j/c$, where $\mathit{v}$ is the velocity of the Earth with respect to the cosmic microwave background restframe and $i$, $j$ represent the equatorial inertial coordinates $X$, $Y$, and $Z$. We constrain all 3 components of $A$, obtaining $1\sigma$ upper limits $|{\mathit{A}}_{X,Y}|\le 1.5\times {10}^{-22}\mathrm{eV}$ and $|{\mathit{A}}_Z|\le 4.4\times {10}^{-21}\mathrm{eV}$ that may be compared to the benchmark value $m_e^2/M_{\mathrm{Planck}}=2\times {10}^{-17}\mathrm{eV}$. Interpreting our constraint on $\mathit{A}$ in terms of noncommutative geometry, we obtain an upper bound of $(355l_{\mathrm{GUT}}{)}^2$ on the minimum observable area, where $l_{\mathrm{GUT}}=\hslash c/({10}^{16}\mathrm{GeV})$ is the grand unification length. We find that $|B|\le 1.2\times {10}^{-19}\mathrm{eV}$. All 9 components of $\mathit{C}$ are constrained at the ${10}^{-17}$ to ${10}^{-18}\mathrm{eV}$ level. We determine 9 linear combinations of parameters of the standard model extension; rotational-noninvariant and boost-noninvariant terms are limited at roughly the ${10}^{-31}\mathrm{GeV}$ and ${10}^{-27}\mathrm{GeV}$ levels, respectively. Finally, we find that the gravitational mass of an electron spinning toward the galactic center differs by less than about 1 part in ${10}^{21}$ from an electron spinning in the opposite direction. As a byproduct of this work, the density of polarized electrons in $\mathrm{Sm}{\mathrm{Co}}_5$ was measured to be $(4.19\pm 0.19)\times {10}^{22}{\mathrm{cm}}^{-3}$ at a field of 9.6 kG.

Based on $58\times {10}^6$ $J/\psi$ events collected with the BESII detector at the Beijing Electron-Positron Collider, the baryon pair processes $J/\psi \to {\Sigma }^{+}{\overline{\Sigma }}^{-}$ and $J/\psi \to {\Xi }^0{\overline{\Xi }}^0$ are observed for the first time. The branching fractions are measured to be $\mathcal{B}(J/\psi \to {\Sigma }^{+}{\overline{\Sigma }}^{-})=(1.50\pm 0.10\pm 0.22)\times {10}^{-3}$ and $\mathcal{B}(J/\psi \to {\Xi }^0{\overline{\Xi }}^0)=(1.20\pm 0.12\pm 0.21)\times {10}^{-3}$, where the first errors are statistical and the second ones are systematic.

We study exclusive ${\chi }_{c0,1,2}$ decays to four-hadron final states involving two charged and two neutral hadrons: ${\pi }^{+}{\pi }^{-}{\pi }^0{\pi }^0$, $K^{+}{K}^{-}{\pi }^0{\pi }^0$, $p\overline{p}{\pi }^0{\pi }^0$, $K^{+}{K}^{-}\eta {\pi }^0$, and $K^{\pm }{\pi }^{\mp }{K}^0{\pi }^0$. The ${\chi }_c$ states are produced in radiative decays of $3.08\times {10}^6$ $\psi (2S)$ resonance decays and observed in the CLEO detector. We also measure the largest substructure contributions to the modes ${\pi }^{+}{\pi }^{-}{\pi }^0{\pi }^0$ and $K^{\pm }{\pi }^{\mp }{K}^0{\pi }^0$.

A new method to amplify the photon-axion conversions in a magnetic field is proposed using a buffer gas at a specific pressure in a photon-regeneration experiment. As a first result, new bounds for mass and coupling constant for laboratory experiments aiming to detect any hypothetical scalars and pseudoscalars, which can couple to photons were obtained, excluding with 95% confidence level, the recently withdrawn PVLAS result.