The spin weighted spherical harmonic (SWSH) description of angular functions is typically associated with the Newman-Penrose (NP) null tetrad formalism. Recently, the SWSH description, but not the NP formalism, has been used in the study of the polarization anisotropy of the cosmic microwave background. Here we relate this application of SWSHs to a description of electromagnetic radiation and polarization in the NP formalism. In particular, we introduce NP Stokes fields that are the NP equivalent of the Stokes parameters. In addition to giving a more coherent foundation for the recent cosmological SWSH application, the NP formalism aids in the computation of the Lorentz transformation properties of polarization.

We study limits on a primordial magnetic field arising from cosmological data, including that from big bang nucleosynthesis, cosmic microwave background polarization plane Faraday rotation limits, and large-scale structure formation. We show that the physically relevant quantity is the value of the effective magnetic field, and limits on it are independent of how the magnetic field was generated.

Ongoing and upcoming surveys in x rays and SZE are expected to jointly detect many clusters due to the large overlap in sky coverage. We show that these clusters can be used as an ensemble of rulers to estimate the angular diameter distance, $d_{\mathrm{A}}(z)$. This comes at no extra observational cost, as these clusters form a subset of a much larger sample, assembled to build cluster number counts, $\frac{dN}{dz}$. On using this $d_{\mathrm{A}}(z)$ the dark energy constraints can be improved by factors of 1.5–4, over those from just $\frac{dN}{dz}$. Even in the presence of a mass follow-up of 100 clusters (done for mass calibration), the dark energy constraints can be further tightened by factors of 2–3 . Adding $d_{\mathrm{A}}(z)$ from clusters is similar to adding $d_{\mathrm{L}}(z)$, from the SNe observations; for eg., $\frac{dN}{dz}$ (from ACT/SPT) plus $d_{\mathrm{A}}(z)$ is comparable to $\frac{dN}{dz}$ plus $d_{\mathrm{L}}(z)$ in constraining ${\Omega }_m$ and ${\sigma }_8$.

The cascade mass reconstruction approach was applied to simulated production of the lightest stop quark at the LHC in the cascade decay $\tilde{g}\to {\tilde{t}}_{1}t\to {\tilde{\chi }}_2^{0}tt\to {\tilde{\ell }}_R\ell tt\to {\tilde{\chi }}_1^0\ell \ell tt$ with top quarks decaying into hadrons. The stop quark mass was reconstructed assuming that the masses of gluino, slepton, and the two lightest neutralinos were reconstructed in advance. A data sample set for the SU3 model point containing 400 k supersymmetry events was generated which corresponded to an integrated luminosity of about $20{\mathrm{fb}}^{-1}$ at 14 TeV. These events were passed through the AcerDET detector simulator, which parametrized the response of a generic LHC detector. The mass of the ${\tilde{t}}_1$ was reconstructed with a precision of about 10%.

Nonperturbative charm and bottom quark-pair production is investigated in the early stage of heavy-ion collisions. The time-dependent study is based on a kinetic description of fermion-pair production in strong non-Abelian fields. We introduce a time-dependent chromo-electric external field with a pulselike time evolution to simulate the overlap of two colliding heavy ions. The calculations is performed in a SU(2) color model with finite current quark masses. Yields of heavy quark pairs are compared to the ones of light and strange quark pairs. We show that the small inverse duration time of the field pulse determines the efficiency of the quark-pair production. The expected suppression for heavy quark production, as follows from the Schwinger formula for a constant field, is not seen, but rather an enhanced heavy quark production appears at ultrarelativistic energies.

We study the fluctuations and correlations of conserved charges, such as the baryon number, the electric charge and the strangeness, at the finite temperature and the nonzero baryon chemical potential in an effective model. The fluctuations are calculated up to the fourth-order and the correlations to the third-order. We find that the second-order fluctuations and correlations have a peak or valley structure when the chiral phase transition takes place with the increase of the baryon chemical potential; the third-order fluctuations and correlations change their signs during the chiral phase transition; and the fourth-order fluctuations have two maxima and one minimum. We also depict contour plots of various fluctuations and correlations of conserved charges in the plane of temperature and the baryon chemical potential. It is found that higher-order fluctuations and correlations of conserved charges are superior to the second-order ones to be used to search for the critical point in heavy ion collision experiments.

Assuming only the nonzero electron and tau neutrino components ${ϵ}_{ee}$, ${ϵ}_{e\tau }$, ${ϵ}_{\tau \tau }$ of the nonstandard matter effect and postulating the atmospheric neutrino constraint ${ϵ}_{\tau \tau }=|{ϵ}_{e\tau }{|}^2/(1+{ϵ}_{ee})$, we study the sensitivity to the nonstandard interaction in neutrino propagation of the T2KK neutrino long-baseline experiment. It is shown that T2KK can constrain the parameters $|{ϵ}_{ee}|\lesssim 1$, $|{ϵ}_{e\tau }|\lesssim 0.2$. It is also shown that if $|{ϵ}_{e\tau }|$ and ${\theta }_{13}$ are large, then T2KK can determine the Dirac phase and the phase of ${ϵ}_{e\tau }$ separately, due to the information at the two baselines. We also provide an argument that the components $|{ϵ}_{\alpha \mu }|$ ($\alpha =e$, $\mu$, $\tau$) must be small for the disappearance oscillation probability to be consistent with high-energy atmospheric neutrino data, which justifies our premise that these quantities are negligible.

We have searched for $B_s^0\to hh$ decays, where $h$ stands for a charged or neutral kaon, or a charged pion. These results are based on a $23.6{\mathrm{fb}}^{-1}$ data sample collected with the Belle detector on the ${\rm Y}(5S)$ resonance at the KEKB asymmetric-energy $e^{+}{e}^{-}$ collider, containing $1.25\times {10}^6$ $B_s^{(*)}{\overline{B}}_s^{(*)}$ events. We observe the decay $B_s^0\to K^{+}{K}^{-}$ and measure its branching fraction, $\mathcal{B}(B_s^0\to K^{+}{K}^{-})=[{3.8}_{-0.9}^{+1.0}(\mathrm{stat})\pm 0.5(\mathrm{syst})\pm 0.5(f_s)]\times {10}^{-5}$. The first error is statistical, the second is systematic, and the third error is due to the uncertainty in the $B_s^0$ production fraction in $e^{+}{e}^{-}\to b\overline{b}$ events. No significant signals are seen in other decay modes, and we set upper limits at the 90% confidence level: $\mathcal{B}(B_s^0\to K^{-}{\pi }^{+})<1.2\times {10}^{-5}$, $\mathcal{B}(B_s^0\to {\pi }^{+}{\pi }^{-})<2.6\times {10}^{-5}$, and $\mathcal{B}(B_s^0\to K^0{\overline{K}}^0)<6.6\times {10}^{-5}$.

The CDF and D0 experiments have reported on the measurement of the forward-backward asymmetry of top quark pair production at the Tevatron and the result is that it is more than 2 standard deviations above the predicted value in the standard model. This has to be added to the long-standing anomaly in the forward-backward asymmetry for bottom quark production at LEP which is 3 standard deviations different from the standard model value. The discrepancy in the bottom asymmetry can be accounted for by the contributions of Kaluza-Klein excitations of electroweak gauge bosons at LEP in warped extra-dimensional models in which the fermions are localized differently along the extra dimension so that the gauge interactions of heavy third generation fermions are naturally different from that of light fermions. In this paper, we show that it is more difficult to elaborate a model generating a significant top asymmetry through exchanges of Kaluza-Klein gluons at the Tevatron due to the indirect constraints originating from precision electroweak data.

Within the class of field theories with the field content of the Skyrme model, one submodel can be found which consists of the square of the baryon current and a potential term only. For this submodel, a Bogomol’nyi-Prasad-Sommerfield bound exists, and the static soliton solutions saturate this bound. Further, already on the classical level, this Bogomol’nyi-Prasad-Sommerfield Skyrme model reproduces some features of the liquid drop model of nuclei. Here, we investigate the model in more detail and, besides, we perform the rigid rotor quantization of the simplest Skyrmion (the nucleon). In addition, we discuss indications that the viability of the model as a low-energy effective field theory for QCD is further improved in the limit of a large number of colors $N_c$.

Using the harmonic superspace approach, we construct the 3D $\mathcal{N}=4$ supersymmetric quantum mechanics of the supermultiplet $(\mathbf{3},\mathbf{4},\mathbf{1})$ coupled to an external SU(2) gauge field. The off-shell $\mathcal{N}=4$ supersymmetry requires the gauge field to be a static form of the ’t Hooft ansatz for the 4D self-dual SU(2) gauge fields, that is a particular solution of Bogomolny equations for Bogomolny-Prasad-Sommerfeld monopoles. We present the explicit form of the corresponding superfield and component actions, as well as of the quantum Hamiltonian and $\mathcal{N}=4$ supercharges. The latter can be used to describe a more general $\mathcal{N}=4$ mechanics system, with an arbitrary Bogomolny-Prasad-Sommerfeld monopole background and on-shell $\mathcal{N}=4$ supersymmetry. The essential feature of our construction is the use of semidynamical spin $(\mathbf{4},\mathbf{4},\mathbf{0})$ multiplet with the Wess-Zumino type action.

As a result of a new improved fit to old bubble chamber data of the dominant axial $C_5^A$ nucleon-to-delta form factor, and due to the relevance of this form factor for neutrino induced coherent pion production, we reevaluate our model predictions in [Phys. Rev. D 79, 013002 (2009)] for different observables of the latter reaction. Central values for the total cross sections increase by $20\%–30\%$, while differential cross sections do not change their shape appreciably. Furthermore, we also compute the uncertainties on total, differential, and flux-averaged cross sections induced by the errors in the determination of $C_5^A$. Our new results turn out to be compatible within about $1\sigma$ with the former ones. Finally, we stress the existing tension between the recent experimental determination of the $\frac{\sigma (\mathrm{CCcoh}{\pi }^{+})}{\sigma (\mathrm{NCcoh}{\pi }^0)}$ ratio by the SciBooNE Collaboration and the theoretical predictions.

We present a consistent renormalization of the top- and bottom-quark/squark sector of the minimal supersymmetric standard model with complex parameters. Various renormalization schemes are defined, analyzed analytically, and tested numerically in the decays ${\tilde{t}}_2\to {\tilde{b}}_i{H}^{+}/W^{+}$ ($i=1$, 2). No scheme is found that produces numerically acceptable results over all the parameter space, where problems occur in most cases already for real parameters. Two schemes are identified that show the most robust behavior. A numerical analysis of the four partial stop decay widths is performed in our “preferred” scheme, “$m_b$, $A_b$ $\overline{\mathrm{DR}}$.” The full one-loop corrections to the corresponding partial decay widths are evaluated, including hard QED and QCD radiation. We find mostly modest corrections at the one-loop level.

Four-quark correlators and the factorization hypothesis are analyzed in the meson sector within chiral perturbation theory. We define the four-quark condensate as $\underset{x\to 0}{lim}⟨T(\overline{q}q)(x)(\overline{q}q)(0)⟩$, which is equivalent to other definitions commonly used in the literature. Factorization of the four-quark condensate holds to leading and next to leading order. However, at next to next to leading order, a term with a nontrivial space-time dependence in the four-quark correlator yields a divergent four-quark condensate, whereas the two-quark condensate and the scalar susceptibility are finite. Such a nonfactorization term vanishes only in the chiral limit. We also comment on how factorization still holds in the large $N_c$ limit, provided such a limit is taken before renormalization.

We investigate the dynamics of a $n$-dimensional domain wall in a $n+1$-dimensional Einstein-Gauss-Bonnet bulk. Exact effective potential induced by the Gauss-Bonnet (GB) term on the wall is derived. In the absence of the GB term we recover the familiar gravitational and antiharmonic oscillator potentials. Inclusion of the GB correction gives rise to a minimum radius of bounce for the Friedmann-Robertson-Walker universe expanding with a negative pressure on the domain wall.

Five-dimensional warped spaces with soft walls are generalizations of the standard Randall-Sundrum compactifications, where instead of an infrared brane one has a curvature singularity (with vanishing warp factor) at finite proper distance in the bulk. We project the physics near the singularity onto a hypersurface located a small distance away from it in the bulk. This results in a completely equivalent description of the soft wall in terms of an effective infrared brane, hiding any singular point. We perform explicitly this calculation for two classes of soft wall backgrounds used in the literature. The procedure has several advantages. It separates in a clean way the physics of the soft wall from the physics of the five-dimensional bulk, facilitating a more direct comparison with standard two-brane warped compactifications. Moreover, consistent soft walls show a sort of universal behavior near the singularity which is reflected in the effective brane Lagrangian. Thirdly, for many purposes, a good approximation is obtained by assuming the bulk background away from the singularity to be the usual Randall-Sundrum metric, thus making the soft wall backgrounds better analytically tractable. We check the validity of this procedure by calculating the spectrum of bulk fields and comparing it to the exact result, finding very good agreement.

Recently we discussed a multimetric gravity theory containing several copies of standard model matter each of which couples to its own metric tensor. This construction contained dark matter sectors interacting repulsively with the visible matter sector and was shown to lead to cosmological late-time acceleration. In order to test the theory with high-precision experiments within the solar system, we here construct a simple extension of the parametrized post-Newtonian (PPN) formalism for multimetric gravitational backgrounds. We show that a simplified version of this extended formalism allows the computation of a subset of the PPN parameters from the linearized field equations. Applying the simplified formalism we find that the PPN parameters of our theory do not agree with the observed values, but we are able to improve the theory so that it becomes consistent with experiments of post-Newtonian gravity and still features its promising cosmological properties.

The covariant entropy bound states that the entropy, $S$, of matter on a light sheet cannot exceed a quarter of its initial area, $A$, in Planck units. The gravitational entropy of black holes saturates this inequality. The entropy of matter systems, however, falls short of saturating the bound in known examples. This puzzling gap has led to speculation that a much stronger bound, $S\lesssim A^{3/4}$, may hold true. In this note, we exhibit light sheets whose entropy exceeds $A^{3/4}$ by arbitrarily large factors. In open Friedmann-Robertson-Walker universes, such light sheets contain the entropy visible in the sky; in the limit of early curvature domination, the covariant bound can be saturated but not violated. As a corollary, we find that the maximum observable matter and radiation entropy in universes with positive (negative) cosmological constant is of order ${\Lambda }^{-1}$ (${\Lambda }^{-2}$), and not $|\Lambda {|}^{-3/4}$ as had hitherto been believed. Our results strengthen the evidence for the covariant entropy bound, while showing that the stronger bound $S\lesssim A^{3/4}$ is not universally valid. We conjecture that the stronger bound does hold for static, weakly gravitating systems.

We construct thin-shell electrically charged wormholes in $d$-dimensional general relativity with a cosmological constant. The wormholes constructed can have different throat geometries, namely, spherical, planar, and hyperbolic. Unlike the spherical geometry, the planar and hyperbolic geometries allow for different topologies and in addition can be interpreted as higher-dimensional domain walls or branes connecting two universes. In the construction we use the cut-and-paste procedure by joining together two identical vacuum spacetime solutions. Properties such as the null energy condition and geodesics are studied. A linear stability analysis around the static solutions is carried out. A general result for stability is obtained from which previous results are recovered.

We argue that the possibility of having infinite energy in the center-of-mass frame of colliding particles is a generic property of rotating black holes. We suggest a general model–independent derivation valid for dirty black holes. The earlier observations for the Kerr or Kerr-Newman metrics are confirmed and generalized.