We study realization of the democratic form of Yukawa matrices by infrared fixed points. We investigate renormalization-group flows of Yukawa couplings in models with a single Yukawa matrix for three families, and up and down-sector Yukawa matrices. It is found that each model has its certain pattern of renormalization-group flows of Yukawa matrices. We apply them to the charged lepton sector and quark sector, and examine in which situation our class of models can lead to realistic results for the mass ratios and mixing angles between the second and third families. We also study corresponding $A$-terms. The $A$-terms approach toward the universal form with no physical $CP$-violating phase. Thus, constraints due to various neutral flavor changing processes except for $\mu \to e\gamma$ are found to be satisfied by this dynamics. In order to suppress the electric dipole moments as well as $\mu \to e\gamma$ sufficiently, more alignment of the $A$-terms with some reason is required.

The first dedicated experiment for the rare kaon decay $K_L^0\to {\pi }^0\nu \overline{\nu }$ has been performed by the E391a Collaboration at the KEK 12-GeV proton synchrotron. A new upper limit of $2.1\times {10}^{-7}$ at the 90% confidence level was set for the branching ratio of the decay $K_L^0\to {\pi }^0\nu \overline{\nu }$ using about 10% of the data collected during the first period of data taking.

I investigate some of the inert phases in three-flavor, spin-zero, color-superconducting quark matter: the color-flavor-locked (CFL) phase (the analogue of the B phase in superfluid ${}^3\mathrm{He}$), the A and A* phases, and the 2SC and sSC phases. I compute the pressure of these phases with and without the neutrality condition. It is shown that the 2SC phase is identical to the A* phase up to a color rotation. The CFL phase is the energetically favored phase except for a small region of intermediate densities where the 2SC/A* phase is favored.

We have investigated the gamma-ray bursts (GRBs) pulses with a fast rise and an exponential decay phase, assumed to arise from relativistically expending fireballs, and found that the curvature effect influences the evolutionary curve of the corresponding hardness ratio (hereafter HRC). We find, due to the curvature effect, the evolutionary curve of the pure hardness ratio (when the background count is not included) would peak at the very beginning of the curve, and then would undergo a drop-to-rise-to-decay phase. In the case of the raw hardness ratio (when the background count is included), the curvature effect would give rise to several types of evolutionary curve, depending on the hardness of a burst. For a soft burst, an upside down pulse of its raw HRC would be observed; for a hard burst, its raw HRC shows a pulselike profile with a sinkage in its decaying phase; for a very hard burst, the raw HRC possesses a pulselike profile without a sinkage in its decaying phase. For a pulselike raw HRC as shown in the case of the hard and very hard bursts, its peak would appear in advance of that of the corresponding light curve, which was observed previously in some GRBs. For illustration, we have studied here the HRC of GRB 920216, GRB 920830, and GRB 990816 in detail. The features of the raw HRC expected in the hard burst are observed in these bursts. A fit to the three bursts shows that the curvature effect alone could indeed account for the predicted characteristics of HRCs. In addition, we find that the observed hardness ratio tends to be harder at the beginning of the pulses than what the curvature effect could predict and be softer at the late time of the pulses. We believe this is an evidence showing the existence of intrinsic hard-to-soft radiation which might be due to the acceleration-to-deceleration mode of shocks.

Recently, a reconsideration of Drell-Yan cross sections at moderate energies and masses has suggested the possibility of relevant enhancements of the cross sections in some kinematical regions. If confirmed, these predictions could largely affect the planning of Drell-Yan experiments aimed at transverse spin measurements after 2010. More in general, the problem is present of a precision measurement of the $\tau$ dependence of Drell-Yan cross sections. Here we discuss the feasibility of such a measurement within short time at the COMPASS apparatus, and its relevance for the PANDA experiment.

We study the deep inelastic process ${\nu }_{\tau }+\mathcal{N}\to {\tau }^{-}+X$ (with $\mathcal{N}\equiv (n+p)/2$ an isoscalar nucleon), in the context of the two Higgs doublet model type two (2HDM(II)). In particular, we discuss the contribution to the total cross section of diagrams, in which a charged Higgs boson is exchanged. We show that for large values of $\tan \beta$ such contribution for an inclusive dispersion generated through the collision of an ultrahigh energy tau-neutrino on a target nucleon can reach up to 57% of the value of the contribution of the $W^{+}$ exchange diagrams (i.e. can reach up to 57% of the standard model (SM) prediction) and could permit to distinguish between the SM and the 2HDM(II) predictions at the Pierre Auger Observatory.

We point out that, if $R$-parity is broken spontaneously, the neutralino can decay to the final state majoron plus neutrino, which from the experimental point of view is indistinguishable from the standard missing momentum signal of supersymmetry. We identify the regions of parameter space where this decay mode is dominant and show that they are independent of $R$-parity conserving SUSY parameters. Thus, (a) only very weak limits on $R$-parity violating couplings can be derived from the observation of missing momentum events and (b) at future collider experiments huge statistics might be necessary to establish that $R$-parity indeed is broken. Parameter combinations which give calculated relic neutralino density larger than the measured dark matter density in case of conserved $R$-parity are valid points in this scenario and their phenomenology at the LHC deserves to be studied.

We show how to resum neutral propagators to all orders in partially quenched chiral perturbation theory. We calculate the relevant quantities to next-to-next-to-leading order (NNLO). Using these results we show how to extend the proposal by Sharpe and Shoresh for determining the parameters relevant for the $\eta$ mass from partially quenched lattice QCD calculations to NNLO.

The $X(3872)$ seems to be a weakly bound hadronic molecule whose constituents are two charm mesons. Its binding energy is much smaller than all the other energy scales in QCD. This separation of scales can be exploited through factorization formulas for production and decay rates of the $X$. In a low-energy effective field theory for the constituents of the $X$, the factorization formulas can be derived using the operator product expansion. The derivations are carried out explicitly for the simplest effective theory in which the constituents interact through a contact interaction that produces a large scattering length. The long-distance factors in the operator product expansions for various observables are calculated nonperturbatively in the interaction strength of the contact interaction. After renormalization of the coupling constant, all remaining ultraviolet divergences can be absorbed into the short-distance factors in the operator product expansions.

In general relativity, the energy conditions are invoked to restrict general energy-momentum tensors $T_{\mu \nu }$ on physical grounds. We show that in the standard Friedmann–Lemaître–Robertson–Walker (FLRW) approach to cosmological modeling where the equation of state of the cosmological fluid is unknown, the energy conditions provide model-independent bounds on the behavior of the distance modulus of cosmic sources as a function of the redshift. We use both the gold and the legacy samples of current type Ia supenovae to carry out a model-independent analysis of the energy conditions violation in the context of standard cosmology.

It is shown that Wess-Zumino-Witten (WZW) type actions can be constructed in odd dimensional space-times using Wilson line or Wilson loop. WZW action constructed using Wilson line gives anomalous gauge variations and the WZW action constructed using Wilson loop gives anomalous chiral transformation. We show that pure gauge theory including Yang-Mills action, Chern-Simons action, and the WZW action can be defined in odd dimensional space-times with even dimensional boundaries. Examples in 3D and 5D are given. We emphasize that this offers a way to generalize gauge theory in odd dimensions. The WZW action constructed using Wilson line cannot be considered as action localized on boundary space-times since it can give anomalous gauge transformations on separated boundaries. We try to show that such WZW action can be obtained in the effective theory when making localized chiral fermions decouple.

The influence of a Lorentz-violating fixed background on fermions is considered by means of a torsion-free nonminimal coupling. The nonrelativistic regime is assessed and the Lorentz-violating Hamiltonian is determined. The effect of this Hamiltonian on the hydrogen spectrum is determined to first-order evaluation (in the absence and in the presence of an external magnetic field), revealing that there appear some energy shifts that modify the fine structure of the spectrum. In the case the nonminimal coupling is torsionlike, no first order correction shows up in the absence of an external field; in the presence of an external field, a secondary Zeeman effect is implied. Such effects are then used to set up stringent bounds on the parameters of the model.

We develop some properties of the non-BPS attractive STU black hole. Our principle result is the construction of exact solutions for the moduli, the metric, and the vectors in terms of appropriate harmonic functions. In addition, we find a spherically symmetric attractor carrying $p^0$ ($D6$ brane) and $q_a$ ($D2$ brane) charges by solving the non-BPS attractor equation (which we present in a particularly compact form) and by minimizing an effective black hole potential. Finally, we make an argument for the existence of multicenter attractors and conjecture that if such solutions exist they may provide a resolution to the existence of apparently unstable non-BPS “attractors.”

In this paper we evaluate finite temperature corrections to the dark matter relic density within the context of minimal supersymmetry with a neutralino as the lightest supersymmetric partner (LSP). We identify several regions of parameter space where the weakly interacting massive particle (WIMP) annihilation cross section is especially sensitive to small corrections to the underlying parameters. In these regions, finite temperature effects have the potential to be important. However, we shall show by explicit calculation that these effects are small. In the regions we investigated, the maximal corrections are on the order of ${10}^{-4}$ and are therefore negligible compared with theoretical and experimental uncertainties.

The retarded Green function of the electromagnetic field in spacetime of a straight thin cosmic string is found. It splits into a geodesic part (corresponding to the propagation along null rays) and to the field scattered on the string. With help of the Green function the electric and magnetic fields of simple sources are constructed. It is shown that these sources are influenced by the cosmic string through a self-interaction with their field. The distant field of static sources is studied and it is found that it has a different multipole structure than in Minkowski spacetime. On the other hand, the string suppresses the electric and magnetic field of distant sources—the field is expelled from regions near the string.

We construct approximate analytical solutions to the constraint equations of general relativity for binary black holes of arbitrary mass ratio in quasicircular orbit. We adopt the puncture method to solve the constraint equations in the transverse-traceless decomposition and consider perturbations of Schwarzschild black holes caused by boosts and the presence of a binary companion. A superposition of these two perturbations then yields approximate, but fully analytic binary black hole initial data that are accurate to first order in the inverse of the binary separation and the square of the black holes’ momenta.

We consider solutions of the four-dimensional Einstein-Yang-Mills (EYM) system with a negative cosmological constant $\Lambda =-3g^2$, where $g$ is the non-Abelian gauge coupling constant. This theory corresponds to a consistent truncation of $\mathcal{N}=4$ gauged supergravity and may be uplifted to $d=11$ supergravity. A systematic study of all known solutions is presented as well as new configurations corresponding to rotating regular dyons and rotating non-Abelian black holes. The thermodynamics of the static black hole solutions is also discussed. The generic EYM solutions present a nonvanishing magnetic flux at infinity and should give us information about the structure of a conformal field theory (CFT) in a background SU(2) field. We argue that the existence of these configurations violating the no-hair conjecture is puzzling from the anti-de Sitter (AdS)/CFT point of view.

Supergravity corrections due to the energy density of a right-handed sneutrino can generate a negative mass squared for the inflaton, flattening the inflaton potential and reducing the spectral index and inflaton energy density. For the case of $D$-term hybrid inflation, we show that the spectral index can be lowered from the conventional value $n=0.98$ to a value within the range favored by the latest WMAP analysis, $n={0.951}_{-0.019}^{+0.015}$. The modified energy density is consistent with nonobservation of cosmic strings in the CMB if $n<0.946$. The WMAP lower bound on the spectral index implies that the $D$-term cosmic string contribution may be very close present CMB limits, contributing at least 5% to the CMB multipoles.

A simple algorithm which gives the multipole vectors in terms of the roots of a polynomial is given. We find that the reported alignment of the low $l$ multipole vectors can be summarized as an orthogonality of these with the dipole direction. This orthogonality is not only present in $l=2$ and 3 but also for $l=5$ and higher. This alignment is likely due to nonlinearity in the data processing. Our results are based on the 3 yr Wilkinson Microwave Anisotropy Probe data, we also list corresponding results for the first year data.

In this letter we discuss the connection between so-called homoclinic chaos and the violation of energy conditions in locally rotationally symmetric Bianchi type IX models, where the matter is assumed to be nontilted dust and a positive cosmological constant. We show that homoclinic chaos in these models is an artifact of unphysical assumptions: it requires that there exist solutions with positive matter energy density $\rho >0$ that evolve through the singularity and beyond as solutions with negative matter energy density $\rho <0$. Homoclinic chaos is absent when it is assumed that the dust particles always retain their positive mass. In addition, we discuss more general models: for solutions that are not locally rotationally symmetric we demonstrate that the construction of extensions through the singularity, which is required for homoclinic chaos, is not possible in general.