Using a recently developed generalized Weyl formalism, we construct an asymptotically flat, static vacuum Einstein solution that describes a superposition of multiple five-dimensional Schwarzschild black holes. The spacetime exhibits a $U\left(1\right)\mathrm{}\times U\left(1\right)\mathrm{}$ rotational symmetry. It is argued that for certain choices of parameters the black holes are collinear and so may be regarded as a five-dimensional generalization of the Israel-Khan solution. The black holes are kept in equilibrium by membranelike conical singularities along the two rotational axes; however, they still distort one another by their mutual gravitational attraction. We also generalize this solution to one describing multiple charged black holes, with fixed mass-to-charge ratio, in Einstein-Maxwell-dilaton theory.

Possible cosmic microwave background radiation (CMBR) correlations are estimated for a model in which a Hubble-size magnetic wall is formed during the QCD chiral phase transition. Measurable polarization correlations are found for l values greater than about 1000. It is also found that metric perturbations from the wall could give rise to observable CMBR correlations for large l.

We use recent results from the Wilkinson Microwave Anisotropy Probe for the locations of peaks and troughs of the cosmic microwave background power spectrum, together with constraints from large-scale structure, to study a quintessence model in which the pure exponential potential is modified by a polynomial factor. Our analysis, in the $\left({\Omega }_m{,h,n}_s\right)$ cosmological parameter space and for a wide range of potential parameters, shows that quintessence is favored compared to the cold dark matter model with a cosmological constant $\left(\Lambda \mathrm{CDM}\right)$ for $n_s\approx 1$ and relatively high values of the average fraction of dark energy before last scattering (“early quintessence”); for $n_s<1,$ quintessence and $\Lambda \mathrm{CDM}$ give similar results, except for high values of early quintessence, in which case $\Lambda \mathrm{CDM}$ is favored.

Ultrahigh energy cosmic ray (UHECR) protons produced by uniformly distributed astrophysical sources contradict the energy spectrum measured by both the AGASA and HiRes experiments, assuming the small scale clustering of UHECRs observed by AGASA is caused by pointlike sources. In that case, the small number of sources leads to a sharp exponential cutoff at the energy $E<\mathrm{}{10}^{20}\mathrm{eV}$ in the UHECR spectrum. New hadrons with a mass of 1.5–3 GeV can solve this cutoff problem. For the first time we discuss the production of such hadrons in proton collisions with infrared or optical photons in astrophysical sources. This production mechanism, in contrast with proton-proton collisions, requires the acceleration of protons only to energies $E\lesssim {10}^{21}\mathrm{eV}.$ The diffuse gamma-ray and neutrino fluxes in this model obey all existing experimental limits. We predict large UHE neutrino fluxes well above the sensitivity of the next generation of high energy neutrino experiments. As an example we study hadrons containing a light bottom squark. This model can be tested by accelerator experiments, UHECR observatories, and neutrino telescopes.

The wave effect in the gravitational lensing phenomenon by a straight cosmic string is investigated. The interference pattern is expressed in terms of a simple formula. We demonstrate that modulations of the interfered wave amplitude can be a unique signature of the wave effect. We briefly mention a possible chance of detecting the wave effect in future gravitational wave observatories.

We make use of a semiclassical method for calculating the suppression exponent for topology changing transitions in high-energy electroweak collisions. In the Standard Model these processes are accompanied by violation of baryon and lepton number. By using a suitable computational technique we obtain results for s-wave scattering in a large region of initial data. Our results show that baryon and lepton number violation remains exponentially suppressed up to very high energies of at least 30 sphaleron masses (250 TeV). We also conclude that the known analytic approaches inferred from low energy expansion provide reasonably good approximations up to the sphaleron energy (8 TeV) only.

We analyze the collective modes of high-temperature QCD in the case when there is an anisotropy in the momentum-space distribution function for the gluons. We perform a tensor decomposition of the gluon self-energy and solve the dispersion relations for both stable and unstable modes. Results are presented for a class of anisotropic distribution functions which can be obtained by stretching or squeezing an isotropic distribution function along one direction in momentum space. We find that there are three stable modes and either one or two unstable modes, depending on whether the distribution function is stretched or squeezed. The presence of unstable modes which have exponential growth can lead to a more rapid thermalization and isotropization of the soft modes in a quark gluon plasma and therefore may play an important role in the dynamical evolution of a quark-gluon plasma.

We consider the flavor structure of supersymmetric theories that can account for the deviation of the observed time-dependent $\mathrm{CP}$ asymmetry in $\overrightarrow{B}\phi K_S$ from the standard model prediction. Assuming simple flavor symmetries and effective field theory, we investigate possible correlations between sizable supersymmetric contributions to $\overrightarrow{b}s$ transitions and to flavor changing processes that are more tightly constrained. With relatively few assumptions, we determine the properties of minimal Yukawa and soft mass textures that are compatible with the desired supersymmetric flavor-changing effect and constraints. We then present explicit models that are designed (at least approximately) to realize these textures. In particular, we present an Abelian model based on a single U(1) factor and a non-trivial extra-dimensional topography that can explain the $\mathrm{CP}$ asymmetry in $\overrightarrow{B}\phi K_S,$ while suppressing other supersymmetric flavor changing effects through a high degree of squark-quark alignment.

Due to the enhancement of the couplings between Higgs bosons and bottom quarks in the minimal supersymmetric standard model (MSSM), the cross section of the process $pp\left(p\overline{p}\right)\to h^0{b(h}^0\overline{b})+X$ at hadron colliders can be considerably enhanced. We investigate the production of a Higgs boson associated with a single high-$p_T$ bottom quark via the subprocess $bg\left(\overline{b}g\right)\to h^0{b(h}^0\overline{b})$ at hadron colliders including the next-to-leading-order (NLO) QCD corrections in the MSSM. We find that the NLO-QCD correction in the MSSM reaches $50\%–70\%$ at the CERN LHC and $60\%–85\%$ at the Fermilab Tevatron in our chosen parameter space.

A recent surge of interest in the novel ideas of large extra dimensions and their implications, such as the early unification of quarks and leptons, has prompted us to revive a paper written 22 years ago. In that paper, we provided a general discussion of quark-lepton unification characterized by the gauge group $G_S\otimes G_W$ with two couplings $g_S$ and $g_W$ and by the unification mass scales $M=10\mathrm{}\mathrm{TeV}–1000\mathrm{TeV}.$ The constraint from ${\sin }^2{\theta }_W$ restricts the choices for $G_W$ and our favorite model for petite unification was chosen to be ${\mathrm{SU}\left(4\right)\mathrm{}}_{\mathrm{PS}}\otimes {\mathrm{SU}\left(2\right)\mathrm{}}^4.$ In the present paper, we review the main results of our earlier paper and propose two new models based on the groups ${\mathrm{SU}\left(4\right)\mathrm{}}_{\mathrm{PS}}\otimes {\mathrm{SU}\left(2\right)\mathrm{}}^3$ and ${\mathrm{SU}\left(4\right)\mathrm{}}_{\mathrm{PS}}\otimes {\mathrm{SU}\left(3\right)\mathrm{}}^2,$ for which the consistency with the measured value of ${\sin }^2{\theta }_W{(M}_Z^2)$ determines the unification scale to be roughly 1 TeV and 3–10 TeV, respectively. The implication of this very early unification is the existence of new quarks and leptons with charges up to 4/3 (for quarks) and 2 (for leptons) and masses $O\left(250\mathrm{}\mathrm{GeV}\right).\mathrm{}$ Interestingly, in these models the rare decay $K_L\to \mu e$ is automatically absent at the tree level and the one-loop contributions are consistent with the experimental upper bound for this decay. On the other hand, the original ${\mathrm{SU}\left(4\right)\mathrm{}}_{\mathrm{PS}}\otimes {\mathrm{SU}\left(2\right)\mathrm{}}^4$ model can be made consistent with the measured value of ${\sin }^2{\theta }_W{(M}_Z^2)$ and the unification scale $M=O\left(1\mathrm{}\mathrm{TeV}\right)$ only provided there exist at least nine ordinary quark and lepton generations, with four generations in the case of the supersymmetric version. Moreover, the solution to the $K_L\to \mu e$ problem is not as natural as in the two other scenarios. We comment on the recent papers on early unification in the context of large extra dimensions.

We consider the production, at future lepton colliders, of charged Higgs boson pairs in the minimal supersymmetric standard model. Assuming a relatively light supersymmetry (SUSY) scenario, we show that, for center of mass energies in the 1 TeV range, a one-loop logarithmic Sudakov expansion that includes an “effective” next-to-subleading order term is adequate to the expected level of experimental accuracy. We consider then the coefficient of the linear (subleading) SUSY Sudakov logarithm and the SUSY next-to-subleading term of the expansion and show that their dependence on the supersymmetric parameters of the model is drastically different. In particular, the coefficient of the SUSY logarithm is only dependent on $\tan \beta$ while the next-to-subleading term depends on a larger set of SUSY parameters. This would allow us to extract from the data separate informations and tests of the model.

We argue that the spin alignment of the vector mesons observed in unpolarized hadron-hadron collisions is closely related to the single-spin left-right asymmetry observed in transversely polarized hadron-hadron collisions. We present the numerical results obtained from the type of spin-correlation imposed by the existence of the single-spin left-right asymmetries. We compare the results with the available data and make predictions for future experiments.

We present in detail the calculation of the $O\left({\alpha }_s^3\right)$ inclusive total cross section for the process $p\overrightarrow{p}t\overline{t}h,$ in the standard model, at the CERN Large Hadron Collider with a center-of-mass energy $\sqrt{s_H}=14\mathrm{}\mathrm{TeV}.$ The calculation is based on the complete set of virtual and real $O\left({\alpha }_s\right)$ corrections to the parton level processes $q\overline{q}\to t\overline{t}h$ and $g\overrightarrow{g}t\overline{t}h,$ as well as the tree level processes $(q,\overline{q})\overrightarrow{g}t\overline{t}h+(q,\overline{q}).\mathrm{}$ The virtual corrections involve the computation of pentagon diagrams with several internal and external massive particles, first encountered in this process. The real corrections are computed using both the single and the two cutoff phase space slicing method. The next-to-leading order QCD corrections significantly reduce the renormalization and factorization scale dependence of the Born cross section and moderately increase the Born cross section for values of the renormalization and factorization scales above $m_t.$

The form of collinear gauge invariance for power suppressed operators in the soft-collinear effective theory (SCET) is discussed. Using a field redefinition we show that it is possible to make any power suppressed ultrasoft-collinear operators invariant under the original leading order gauge transformations. Our manipulations avoid gauge fixing. The Lagrangians to $\mathcal{O}\left({\lambda }^2\right)$ are given in terms of these new fields. We then give a simple procedure for constructing power suppressed soft-collinear operators in ${\mathrm{SCET}}_{\mathrm{II}}$ by using an intermediate theory ${\mathrm{SCET}}_{\mathrm{I}}.$

The first data released by the KamLAND Collaboration have confirmed the strong evidence in favor of the large mixing angle solution of the solar neutrino problem. Taking into account the ranges for the oscillation parameters allowed by the global analysis of the solar, CHOOZ and KamLAND data, we update the limits on the neutrinoless double beta decay effective neutrino mass parameter and analyze the impact of all the available data from neutrinoless double beta decay experiments on the neutrino mass bounds, in view of the latest WMAP results. For the normal neutrino mass spectrum the range (0.05–0.23) eV is obtained for the lightest neutrino mass if one takes into account the Heidelberg-Moscow evidence for neutrinoless double beta decay and the cosmological bound. It is also shown that under the same conditions the mass of the lightest neutrino may not be bounded from below if the spectrum is of the inverted type. Finally, we discuss how future experiments can improve the present bounds on the lightest neutrino mass set by the Troitsk, Mainz, and Wilkinson microwave anisotropy probe results.

Contributions from light-by-light scattering to ${(g}_{\mu }-2)/2,$ the anomalous magnetic moment of the muon, are mediated by the exchange of charged fermions or scalar bosons. Assuming large masses M, pointlike couplings for the virtual particles and employing the technique of large mass expansion, analytical results are obtained for virtual fermions and scalars in the form of a series in ${(m}_{\mu }{/M)}^2.$ This series is well convergent even for the case ${M=m}_{\mu }.$ For pointlike virtual fermions, the expansion confirms published analytical formulas. For virtual scalars, the result can be used to evaluate the contribution from pointlike charged pions. In this case our result confirms already available numerical evaluations; however, it is significantly more precise.

The possibility of measuring ${\sin }^{2}2{\theta }_{13}$ using reactor neutrinos is examined in detail. It is shown that the sensitivity ${\sin }^{2}2{\theta }_{13}>0.02\mathrm{}$ can be reached with 40 ton yr data by placing identical CHOOZ-like detectors at near and far distances from a giant nuclear power plant whose total thermal energy is $24.3{\mathrm{GW}}_{\mathrm{th}}.$ It is emphasized that this measurement is free from the parameter degeneracies that occur in accelerator appearance experiments, and therefore the reactor measurement is complementary to accelerator experiments. It is also shown that the reactor measurement may be able to resolve the degeneracy in ${\theta }_{23}$ if ${\sin }^{2}2{\theta }_{13}$ and ${\cos }^{2}2{\theta }_{23}$ are relatively large.

It is well known that gravity and neutrino oscillation can be used to probe large extra dimensions in a braneworld scenario. We argue that neutrino oscillation remains a useful probe even when the extra dimensions are small, because the brane-bulk coupling is likely to be large. Neutrino oscillation in the presence of a strong brane-bulk coupling is vastly different from the usual case of a weak coupling. In particular, some active neutrinos could be absorbed by the bulk when they oscillate from one kind to another, a signature which can be taken as the presence of an extra dimension. In a very large class of models which we shall discuss, the amount of absorption for all neutrino oscillations is controlled by a single parameter, a property which distinguishes extra dimensions from other mechanisms for losing neutrino fluxes.

Using 13.5 ${\mathrm{fb}}^{-1}$ of $e^{+}{e}^{-}$ annihilation data collected with the CLEO II detector, we have observed a narrow resonance decaying to $D_s^{*+}{\pi }^0$ with a mass near $2.46\mathrm{GeV}{/c}^2.$ The search for such a state was motivated by the recent discovery by the BaBar Collaboration of a narrow state at $2.32\mathrm{GeV}{/c}^2,$ the $D_{\mathrm{sJ}}^{*}{\mathrm{}\left(2317\right)\mathrm{}}^{+},$ that decays to $D_s^{+}{\pi }^0.$ Reconstructing the $D_s^{+}{\pi }^0$ and $D_s^{*+}{\pi }^0$ final states in CLEO data, we observe peaks in both of the corresponding reconstructed mass difference distributions, $\Delta {M(D}_s{\pi }^0{)=M(D}_s{\pi }^0\left)-{M(D}_s\right)$ and $\Delta {M(D}_s^{*}{\pi }^0{)=M(D}_s^{*}{\pi }^0\left)-{M(D}_s^{*}\right),$ both of them at values near $350\mathrm{MeV}{/c}^2.$ We interpret these peaks as signatures of two distinct states, the $D_{\mathrm{sJ}}^{*}{\mathrm{}\left(2317\right)\mathrm{}}^{+}$ plus a new state, designated as the $D_{\mathrm{sJ}}{\mathrm{}\left(2463\right)\mathrm{}}^{+}.$ Because of the similar $\Delta M$ values, each of these states represents a source of background for the other if photons are lost, ignored or added. A quantitative accounting of these reflections confirms that both states exist. We have measured the mean mass differences $〈\Delta {M(D}_s{\pi }^0)〉=350.0\mathrm{}\pm 1.2(\mathrm{stat})\pm 1.0(\mathrm{syst})\mathrm{MeV}{/c}^2$ for the $D_{\mathrm{sJ}}^{*}{\mathrm{}\left(2317\right)\mathrm{}}^{+}$ state, and $〈\Delta {M(D}_s^{*}{\pi }^0)〉=351.2\mathrm{}\pm 1.7(\mathrm{stat})\pm 1.0(\mathrm{syst})\mathrm{MeV}{/c}^2$ for the new $D_{\mathrm{sJ}}{\mathrm{}\left(2463\right)\mathrm{}}^{+}$ state. We have also searched, but find no evidence, for decays of the two states via the channels $D_s^{*+}\gamma ,D_s^{+}\gamma ,$ and $D_s^{+}{\pi }^{+}{\pi }^{-}.$ The observations of the two states at 2.32 and $2.46\mathrm{GeV}{/c}^2,$ in the $D_s^{+}{\pi }^0$ and $D_s^{*+}{\pi }^0$ decay channels, respectively, are consistent with their interpretations as $c\overline{s}$ mesons with an orbital angular momentum $L=1\mathrm{}$ and spin and parity $J^P{=0\mathrm{}}^{+}$ and $1^{+}.$

Some of the peculiar electrodynamical effects associated with gauged “dimension bubbles” are presented. Such bubbles, which effectively enclose a region of 5D spacetime, can arise from a 5D theory with a compact extra dimension. Bubbles with thin domain walls can be stabilized against total collapse by the entrapment of light charged scalar bosons inside the bubble, extending the idea of a neutral dimension bubble to accommodate the case of a gauged U(1) symmetry. Using a dielectric approach to the 4D dilaton-Maxwell theory, it is seen that the bubble wall is almost totally opaque to photons, leading to a new stabilization mechanism due to trapped photons. Photon dominated bubbles very slowly shrink, resulting in a temperature increase inside the bubble. At some critical temperature, however, these bubbles explode, with a release of radiation.