Motivated by the recent observation of the high energy electron and positron excesses in cosmic ray by PAMELA and ATIC/PPB-BETS, we suggest an anomaly-free scenario for the universal extra dimension that localizes the standard model quarks and splits the spectrum of Kaluza-Klein (KK) quarks from KK leptons. When the SM quarks are “well localized” at the boundaries, the most stringent bound of the model ($1/R>510\mathrm{GeV}$) comes from the resonance search for the Tevatron dijet channels. Even at the early stage of LHC, one can discover the second KK gluon for masses up to 4 TeV.

We provide ready-to-use time-domain gravitational waveforms for spinning compact binaries with precession effects through 1.5 post-Newtonian (PN) order in amplitude, and compute their mode decomposition using spin-weighted $-2$ spherical harmonics. In the presence of precession, the gravitational-wave modes $(\ell ,m)$ contain harmonics originating from combinations of the orbital frequency and precession frequencies. We find that the gravitational radiation from binary systems with large mass asymmetry and large inclination angle can be distributed among several modes. For example, during the last stages of inspiral, for some maximally spinning configurations, the amplitude of the (2, 0) and (2, 1) modes can be comparable to the amplitude of the (2, 2) mode. If the mass ratio is not too extreme, the $\ell =3$ and $\ell =4$ modes are generally 1 or 2 orders of magnitude smaller than the $\ell =2$ modes. Restricting ourselves to spinning, nonprecessing compact binaries, we apply the stationary-phase approximation and derive the frequency-domain gravitational waveforms including spin-orbit and spin(1)-spin(2) effects through 1.5PN and 2PN order, respectively, in amplitude, and 2.5PN order in phase. Since spin effects in the amplitude through 2PN order affect only the first and second harmonics of the orbital phase, they do not extend the mass reach of gravitational-wave detectors. However, they can interfere with other harmonics and lower or raise the signal-to-noise ratio depending on the spin orientation. These ready-to-use waveforms could be employed in the data analysis of the spinning, inspiraling binaries as well as in comparison studies at the interface between analytical and numerical relativity.

Recent advances in space-qualified atomic clocks (low-mass, low power-consumption, frequency stability comparable to that of ground-based clocks) can enable interplanetary spacecraft radio science experiments at unprecedented Doppler sensitivities. The addition of an on-board digital receiver would allow the up- and down-link Doppler frequencies to be measured separately. Such separate, high-quality measurements allow optimal data combinations that suppress the currently leading noise sources: phase scintillation noise from the Earth’s atmosphere and Doppler noise caused by mechanical vibrations of the ground antenna. Here we provide a general expression for the optimal combination of ground and on-board Doppler data and compute the sensitivity such a system would have to low-frequency gravitational waves (GWs). Assuming a plasma scintillation noise calibration comparable to that already demonstrated with the multilink CASSINI radio system, the space-clock/digital-receiver instrumentation enhancements would give GW strain sensitivity of $3.7\times {10}^{-14}{\mathrm{Hz}}^{-1/2}$ for randomly polarized, monochromatic GW signals isotropically distributed over the celestial sphere, over a two-decade ($\sim 0.0001–0.01\mathrm{Hz}$) region of the low-frequency band. This is about an order of magnitude better than currently achieved with traditional two-way coherent Doppler experiments. The utility of optimally combining simultaneous up- and down-link observations is not limited to GW searches. The Doppler tracking technique discussed here could be performed at minimal incremental cost to improve also other radio science experiments (i.e., tests of relativistic gravity, planetary and satellite gravity field measurements, atmospheric and ring occultations) on future interplanetary missions.

We study numerically black-hole formation from a collapsing massless scalar field. The use of Painlevé-Gullstrand coordinates allows the evolution to proceed until singularity formation. We generate spacetime maps of the collapse, illustrating the evolution of apparent horizons for various initial data. A study of the Choptuik scaling reveals the expected universal values for the critical exponent and echoing period. The periodic oscillations in the supercritical horizon scaling relation, while universal with respect to initial Painlevé-Gullstrand data, show unexpected structure with large amplitude cusps.

We present a locally supersymmetric extension of the minimal supersymmetric standard model (MSSM) based on the gauge group $SU(3{)}_C\times SU(2{)}_L\times U(1{)}_Y\times U(1{)}^{\prime }$ where, except for the supersymmetry-breaking scale which is fixed to be $\sim {10}^{11}\mathrm{GeV}$, we require that all non-standard-model parameters allowed by the local spacetime and gauge symmetries assume their natural values. The $U(1{)}^{\prime }$ symmetry, which is spontaneously broken at the intermediate scale, serves to (i) explain the weak scale magnitudes of $\mu$ and $b_{\mu }$ terms, (ii) ensure that dimension-3 and dimension-4 baryon-number-violating superpotential operators (and, in a class of models, all $\Delta B=1$ operators) are forbidden, solving the proton-lifetime problem, and (iii) predict bilinear lepton-number violation in the superpotential at just the right level to accommodate the observed mass and mixing pattern of active neutrinos (leading to a novel connection between the SUSY-breaking scale and neutrino masses), while corresponding trilinear operators are strongly suppressed. The phenomenology is like that of the MSSM with bilinear $R$-parity violation, where the would-be lightest supersymmetric particle decays leptonically with a lifetime of $\sim {10}^{-12}–{10}^{-8}\mathrm{s}$. Theoretical consistency of our model requires the existence of multi-TeV, stable, color-triplet, weak-isosinglet scalars or fermions, with either conventional or exotic electric charge which should be readily detectable if they are within the kinematic reach of a hadron collider. Null results of searches for heavy exotic isotopes imply that the reheating temperature of our Universe must have been below their mass scale which, in turn, suggests that sphalerons play a key role for baryogenesis. Finally, the dark matter cannot be the weakly interacting neutralino.

We make a detailed study of the longitudinal polarization of hyperons and antihyperons in semi-inclusive deep-inelastic lepton-nucleon scattering. We present the numerical results for spin transfer in quark fragmentation processes, and analyze the possible origins for a difference between the polarization for hyperon and that for the corresponding antihyperon. We present the results obtained in the case that there is no asymmetry between sea and antisea distribution in the nucleon as well as those obtained when such an asymmetry is taken into account. We compare the results with the available data such as those from COMPASS and make predictions for future experiments including those at even higher energies such as at eRHIC.

New superconformal extensions of $d=1$ Calogero-type systems are obtained by gauging the $\mathrm{U}(n)$ isometry of matrix superfield models. We consider the cases of $\mathcal{N}=1$, $\mathcal{N}=2$, and $\mathcal{N}=4$ as one-dimensional supersymmetries. The bosonic core of the $\mathcal{N}=1$ and $\mathcal{N}=2$ models is the standard conformal $A_{n-1}$ Calogero system, whereas the $\mathcal{N}=4$ model is an extension of the U(2)-spin Calogero system.

This paper devises a procedure for adding fundamental and momentum charges to a neutral 5d solution of Einstein’s vacuum equations, when the solution has three Killing vectors. This procedure uses the standard method of boosting and T-dualising a generic metric to give a new two-charge 5d solution to Einstein’s vacuum equations. The physical properties of the charged solution are derived and their implications for the solution are then examined, with the two-charge dual spinning black ring being used as an example.

We discuss the localization of scalar, fermion, and gauge field zero modes on a 3-brane that resides at the intersection of two 4-branes in six-dimensional anti-de Sitter space. This setup has been introduced in the context of braneworld models and, higher-dimensional versions of it, in string theory. In both six- and ten-dimensional cases, it has been shown that four-dimensional gravity can be reproduced at the intersection, due to the existence of a massless, localized graviton zero-mode. However, realistic scenarios require also the standard model to be localized on the 3-brane. In this paper, we discuss under which conditions a higher-dimensional field theory, propagating on the above geometry, can have a zero-mode sector localized at the intersection and find that zero modes can be localized only if masses and couplings to the background curvature satisfy certain relations. We also consider the case when other 4-branes cut the bulk at some distance from the intersection and argue that, in the probe brane approximation, there is no significant effect on the localization properties at the 3-brane. The case of bulk fermions is particularly interesting, since the properties of the geometry allow localization of chiral modes independently.

The angular power spectrum of the cosmic microwave background temperature anisotropy observed by WMAP has an anomalous dip at $\ell \sim 20$ and a bump at $\ell \sim 40$. One explanation for this structure is the presence of features in the primordial curvature power spectrum, possibly caused by a step in the inflationary potential. The detection of these features is only marginally significant from temperature data alone. However, the inflationary feature hypothesis predicts a specific shape for the $E$-mode polarization power spectrum with a structure similar to that observed in temperature at $\ell \sim 20–40$. Measurement of the CMB polarization on few-degree scales can therefore be used as a consistency check of the hypothesis. The Planck satellite has the statistical sensitivity to confirm or rule out the model that best fits the temperature features with $3\sigma$ significance, assuming all other parameters are known. With a cosmic variance limited experiment, this significance improves to $8\sigma$. For tests of inflationary models that can explain both the dip and the bump in temperature, the primary source of uncertainty is confusion with polarization features created by a complex reionization history, which, at most, reduces the significance to $2.5\sigma$ for Planck and $5\sigma –6\sigma$ for an ideal experiment. Smoothing of the polarization spectrum by a large tensor component only slightly reduces the ability of polarization to test for inflationary features, as does requiring that polarization is consistent with the observed temperature spectrum, given the expected low level of $TE$ correlation on few-degree scales. If polarized foregrounds can be adequately subtracted, Planck will supply valuable evidence for or against features in the primordial power spectrum. A future high-sensitivity polarization satellite would enable a decisive test of the feature hypothesis and provide complementary information about the shape of a possible step in the inflationary potential.

Combining a recent derivation of the CMB evolution equations for homogeneous but anisotropic (Bianchi) cosmologies with an account of the full linearized dynamical freedoms available in such models, I calculate and discuss the various temperature and polarization anisotropy patterns that may be formed. Certain anisotropies can be hidden in superhorizon modes at early times, thus avoiding any constraints from nucleosynthesis, while nevertheless producing nontrivial redshift-zero temperature patterns in flat and open universes. The results are likely to be more of pedagogical than observational interest, but future work will assess whether such patterns can be matched to anomalies in WMAP results.

We investigate the possibility for $k$-essence dynamics to reproduce the primary features of inflation in the early universe, generate dark matter subsequently, and finally account for the presently observed acceleration. We first show that for a purely kinetic $k$-essence model the late-time energy density of the universe when expressed simply as a sum of a cosmological constant and a dark matter term leads to a static universe. We then study another $k$-essence model in which the Lagrangian contains a potential for the scalar field as well as a noncanonical kinetic term. We show that such a model generates the basic features of inflation in the early universe, and also gives rise to dark matter and dark energy at appropriate subsequent stages. Observational constraints on the parameters of this model are obtained.

As a model of the current accelerated expansion of the Universe, we consider a model of the scalar-Einstein-Gauss-Bonnet gravity. This model includes the propagating scalar modes, which might give a large correction to the Newton law. In order to avoid this problem, we propose an extension of the chameleon mechanism where the scalar mode becomes massive due to the coupling with the Gauss-Bonnet term. Since the Gauss-Bonnet invariant does not vanish near the Earth or in the Solar System, even in the vacuum, the scalar mode is massive even in the vacuum and the correction to the Newton law could be small. We also discuss the possibility that the model could describe simultaneously the inflation in the early Universe, in addition to the current accelerated expansion.

We revisit the mechanism for violating the weak cosmic-censorship conjecture (WCCC) by overspinning a nearly-extreme charged black hole. The mechanism consists of an incoming massless neutral scalar particle, with low energy and large angular momentum, tunneling into the hole. We investigate the effect of the large angular momentum of the incoming particle on the background geometry and address recent claims that such a backreaction would invalidate the mechanism. We show that the large angular momentum of the incident particle does not constitute an obvious impediment to the success of the overspinning quantum mechanism, although the induced backreaction turns out to be essential to restoring the validity of the WCCC in the classical regime. These results seem to endorse the view that the “cosmic censor” may be oblivious to processes involving quantum effects.

We study the accuracy of the bound-state parameters obtained with the method of dispersive sum rules, one of the most popular theoretical approaches in nonperturbative QCD and hadron physics. We make use of a quantum-mechanical potential model since it provides the only possibility to probe the reliability and the accuracy of this method: one obtains the bound-state parameters from sum rules and compares these results with the exact values calculated from the Schrödinger equation. We investigate various possibilities to fix the crucial ingredient of the method of sum rules—the effective continuum threshold—and propose modifications which lead to a remarkable improvement of the accuracy of the extracted ground-state parameters compared to the standard procedures adopted in the method. Although the rigorous control of systematic uncertainties in the method of sum rules remains unfeasible, the application of the proposed procedures in QCD promises a considerable increase of the actual accuracy of the extracted hadron parameters.

Gauge-Higgs unification in warped extra dimensions provides an attractive solution to the hierarchy problem. The extension of the standard model gauge symmetry to $SO(5)\times U(1{)}_X$ allows the incorporation of the custodial symmetry $SU(2{)}_R$ plus a Higgs boson doublet with the right quantum numbers under the gauge group. In the minimal model, the Higgs mass is in the range 110–150 GeV, while a light Kaluza-Klein excitation of the top quark appears in the spectrum, providing agreement with precision electroweak measurements and a possible test of the model at a high luminosity LHC. The extension of the model to the lepton sector has several interesting features. We discuss the conditions necessary to obtain realistic charged lepton and neutrino masses. After the addition of an exchange symmetry in the bulk, we show that the odd neutrino Kaluza-Klein modes provide a realistic dark-matter candidate, with a mass of the order of 1 TeV, which will be probed by direct dark-matter detection experiments in the near future.

In the framework of the left-right twin Higgs model, we study pair production of the neutral Higgs bosons at the International Linear Collider (ILC) and the CERN LHC. We find that the production cross section of the process $e^{+}{e}^{-}\to {\varphi }^{0}h$ are at the level of several tens fb at the ILC, the production cross section of the ${\varphi }^0{\varphi }^0$ pair and ${\varphi }^{0}h$ pair are at the level of several hundreds fb at the LHC. As long as the neutral Higgs boson ${\varphi }^0$ is not too heavy, we conclude that its pair production might be used to test for the left-right twin Higgs model at the LHC experiment or in the future ILC experiment.

We point out that annihilation of dark matter in the galactic halo can be enhanced relative to that in the early Universe due to a Breit-Wigner tail, if the dark matter annihilates through a pole just below the threshold. This provides a new explanation to the “boost factor” which is suggested by the recent data of the PAMELA, ATIC and PPB-BETS cosmic ray experiments.

We report a measurement of the production cross section for $b$ hadrons in $p\overline{p}$ collisions at $\sqrt{s}=1.96\mathrm{TeV}$. Using a data sample derived from an integrated luminosity of $83{\mathrm{pb}}^{-1}$ collected with the upgraded Collider Detector (CDF II) at the Fermilab Tevatron, we analyze $b$ hadrons, $H_b$, partially reconstructed in the semileptonic decay mode $H_b\to {\mu }^{-}{D}^{0}X$. Our measurement of the inclusive production cross section for $b$ hadrons with transverse momentum $p_T>9\mathrm{GeV}/c$ and rapidity $|y|<0.6$ is $\sigma =1.30\mu \mathrm{b}\pm 0.05\mu \mathrm{b}(\mathrm{stat})\pm 0.14\mu \mathrm{b}(\mathrm{syst})\pm 0.07\mu \mathrm{b}(\mathcal{B})$, where the uncertainties are statistical, systematic, and from branching fractions, respectively. The differential cross sections $d\sigma /d{p}_T$ are found to be in good agreement with recent measurements of the $H_b$ cross section and well described by fixed-order next-to-leading logarithm predictions.

We add an initial nonhomogeneous perturbation to an otherwise homogeneous condensing tachyon background and compute its spacetime energy-momentum tensor from world-sheet string theory. We show that in the far future the energy-momentum tensor corresponds to nonhomogeneous pressureless tachyon matter.