We study a finite $\mathrm{SU}\left(5\right)\mathrm{}$ grand unified model based on the non-Abelian discrete symmetry $A_4.$ This model leads to the democratic structure of the mass matrices for the quarks and leptons. In the soft supersymmetry breaking sector, the scalar trilinear couplings are aligned and the soft scalar masses are degenerate, thus solving the SUSY flavor problem.

In the Randall-Sundrum model, the radion-Higgs mixing is weakly suppressed by the effective electroweak scale. A novel feature of the existence of gravity-scalar mixing would be a sizable three-point vertex, $h_{\mu \nu }^{\mathrm{}\left(n\right)\mathrm{}}-h-\phi .$ We study this vertex in the process $e^{+}{e}^{-}\to h_{\mu \nu }^{\mathrm{}\left(n\right)\mathrm{}}\to h\phi ,$ which is allowed only with a nonzero radion-Higgs mixing. It is shown that the angular distribution is a unique characteristic of the exchange of massive spin-2 gravitons, and the total cross section at the future $e^{+}{e}^{-}$ colliders is big enough to cover a large portion of the parameter space that the LEP or LEP II data cannot constrain.

We study the forward-backward asymmetries in the decays of $K^{+}\to {\pi }^{+}{l}^{+}{l}^{-}$ $(l=e$ and μ) in the presence of scalar or tensor terms. We find that with the scalar [tensor] type interaction the asymmetry can be up to ${O(10\mathrm{}}^{-3})$ $\left[{O(10\mathrm{}}^{-1}\right)]$ and arbitrarily large for the electron and muon modes, respectively, without conflict with the experimental data. We also discuss the cases in the minimal supersymmetric standard model where the scalar terms can be induced. In particular, we show that the asymmetry in $K^{+}\to {\pi }^{+}{\mu }^{+}{\mu }^{-}$ can be as large as ${O(10\mathrm{}}^{-3})$ in the large $\tan \beta$ limit, which can be tested in future experiments such as the CKM experiment at Fermilab.

The $\mathrm{CP}$-violating charge asymmetry in the decays $K^{\pm }\to {\pi }^{\pm }\gamma \gamma ,$ which is induced by the electromagnetic penguin operators, has been studied both in the standard model and in its extensions. Because of a large enhancement of the Wilson coefficients of the electromagnetic penguin operators in the supersymmetric extensions of the standard model, a significant upper bound on this charge asymmetry could be expected, and thus high-precision measurements of this interesting $\mathrm{CP}$-violating quantity might explore new physics effects beyond the standard model.

We give a more transparent understanding of the vacuum expectation value of the renormalized local operator $A^2$ by relating it to the gluon propagator integrated over the momentum. The quadratically divergent perturbative contribution is subtracted and the remainder, dominantly due to the ${O(1/p}^2)$ correction to the perturbative propagator at large $p^2$ is logarithmically divergent. This provides a transparent derivation of the fact that this ${O(1/p}^2)$ term is related to the vacuum expectation value of the local $A^2$ operator and confirms a previous claim based on the operator product expansion (OPE) of the gluon propagator. At leading logarithms the agreement is quantitative, with a standard running factor, between the local $A^2$ condensate renormalized as described above and the one renormalized in the OPE context. This result supports the claim that the BRST invariant Landau-gauge $A^2$ condensate might play an important role in describing the QCD vacuum.

Recently computed terms of order $\mathcal{O}\left({\alpha }_s^4{n}_f^2\right)$ in the perturbative series for the $\tau$ decay rate, and similar (new) strange quark mass corrections, are used to discuss the validity of various optimization schemes. The results are then employed to arrive at improved predictions for the complete terms of order $\mathcal{O}\left({\alpha }_s^4\right)$ and $\mathcal{O}\left({\alpha }_s^5\right)$ in the massless limit as well as for terms due to the strange quark mass. The phenomenological implications are presented.

The measurement of the atmospheric muon spectrum is currently of great interest because of the study of atmospheric neutrinos and the claim of neutrino oscillations made in 1998 by the Super-Kamiokande Collaboration. A measurement of the muon flux is an indirect measure of the neutrino flux. Therefore, it can be used to improve the calculation of the atmospheric neutrino flux, which in turn can be compared with the observed neutrino rates in underground detectors. This article reports a new measurement of the ${\mu }^{+}$ and ${\mu }^{-}$ spectra at several atmospheric depths in the momentum ranges $0.3–20\mathrm{GeV}/c$ and $0.3–40\mathrm{GeV}/c,$ respectively. The data were collected by the balloon-borne experiment CAPRICE98 during the ascent of the payload on 28 May 1998 from Fort Sumner, N. M. The experiment used the NMSU-WIZARD/CAPRICE 98 balloon-borne magnet spectrometer equipped with a gas ring imaging Cherenkov detector and a silicon-tungsten calorimeter.

We measure the $B^0$ lifetime ${\tau }_{B^0}$ and the $B^0-B^0$ oscillation frequency $\Delta m_d$ with a sample of approximately 14000 exclusively reconstructed $B^0\to D^{*-}{\mathcal{l}}^{+}{\nu }_{\mathcal{l}}$ signal events, selected from 23 million $B\overline{B}$ pairs recorded at the ${\rm Y}\mathrm{}\left(4S\right)\mathrm{}$ resonance with the BABAR detector at the Stanford Linear Accelerator Center. The decay position of the other B is determined with the remaining tracks in the event, and its b-quark flavor at the time of decay is determined with a tagging algorithm that exploits the correlation between the flavor of the b quark and the charges of its decay products. The lifetime and oscillation frequencies are measured simultaneously with an unbinned maximum-likelihood fit that uses, for each event, the measured difference in decay times of the two B mesons $\left(\Delta t\right),$ the calculated uncertainty on $\Delta t,$ the signal and background probabilities, and b-quark tagging information for the other B. The results are ${\tau }_{B^0}{=(1.523\mathrm{}}_{-0.023}^{+0.024\mathrm{}}\pm 0.022)\mathrm{ps}$ and $\Delta m_d=(0.492\mathrm{}\pm 0.018\pm 0.013){\mathrm{ps}}^{-1}.$ The statistical correlation coefficient between ${\tau }_{B^0}$ and $\Delta m_d$ is -0.22.

We develop a method to measure the Cabibbo-Kobayashi-Maskawa angle $\gamma$ without hadronic uncertainties from the analysis of $B^{\pm }\to K^{\pm }{D}^0$ and $K^{\pm }{D}^0$ followed by singly Cabibbo-suppressed D decays to non-$\mathrm{CP}$ eigenstates, such as $K^{\pm }{K}^{*\mp }.$ This method utilizes the interference between $\overrightarrow{b}cūs$ and $\overrightarrow{b}u\overline{c}s$ decays, and we point out several attractive features of it. All the modes that need to be measured for this method are accessible in the present data.

We consider the possibility that the standard model Higgs fields may originate from extra components of higher dimensional gauge fields. Theories of this type considered before have had problems accommodating the standard model fermion content and Yukawa couplings different from the gauge coupling. Considering orbifolds based on Abelian discrete groups we are led to a 6 dimensional $G_2$ gauge theory compactified on $T^2{/Z}_4.$ This theory can naturally produce the SM Higgs fields with the right quantum numbers while predicting the value of the weak mixing angle ${\sin }^2{\theta }_W=0.25\mathrm{}$ at the tree level, close to the experimentally observed one. The quartic scalar coupling for the Higgs boson is generated by the higher dimensional gauge interaction and predicts the existence of a light Higgs boson. We point out that one can write a quadratically divergent counterterm for Higgs boson mass localized to the orbifold fixed point. However, we calculate these operators and show that higher dimensional gauge interactions do not generate them at least at one loop. Fermions are introduced at orbifold fixed points, making it easy to accommodate the standard model fermion content. Yukawa interactions are generated by Wilson lines. They may be generated by the exchange of massive bulk fermions, and the fermion mass hierarchy can be obtained. Around a TeV, the first KK modes would appear as well as additional fermion modes localized at the fixed point needed to cancel the quadratic divergences from the Yukawa interactions. The cutoff scale of the theory could be a few times 10 TeV.

Anderson et al. find the measured trajectories of Pioneer 10 and 11 spacecrafts deviate from the trajectories computed from known forces acting on them. This unmodeled acceleration (and the less well known, but similar, unmodeled torque) can be accounted for by non-isotropic radiation of spacecraft heat. Various forms of non-isotropic radiation were proposed by Katz, Murphy, and Scheffer, but Anderson et al. felt that none of these could explain the observed effect. This paper calculates the known effects in more detail and considers new sources of radiation, all based on spacecraft construction. These effects are then modeled over the duration of the experiment. The model reproduces the acceleration from its appearance at a heliocentric distance of 5 AU to the last measurement at 71 AU to within 10%. However, it predicts a larger decrease in acceleration between intervals I and III of the Pioneer 10 observations than is observed. This is a $2\sigma$ discrepancy from the average of the three analyses (SIGMA, CHASMP, and Markwardt). A more complex (but more speculative) model provides a somewhat better fit. Radiation forces can also plausibly explain the previously unmodeled torques, including the spindown of Pioneer 10 that is directly proportional to spacecraft bus heat, and the slow but constant spin-up of Pioneer 11. In any case, by accounting for the bulk of the acceleration, the proposed mechanism makes it much more likely that the entire effect can be explained without the need for new physics.

We present an exact expression for the quasinormal modes of scalar, electromagnetic, and gravitational perturbations of a near extremal Schwarzschild–de Sitter black hole and we show that is why a previous approximation holds exactly in this near extremal regime. In particular, our results give the asymptotic behavior of the quasinormal frequencies for highly damped modes, which has recently attracted much attention due to the proposed identification of its real part with the Barbero-Immirzi parameter.

The massless scalar field in the higher-dimensional Kerr black hole (Myers-Perry solution with a single rotation axis) has been investigated. It was shown that the field equation is separable in arbitrary dimensions. The quasinormal modes of the scalar field were searched in five dimensions using the continued fraction method. The numerical result shows evidence for the stability of the scalar perturbation of five-dimensional Kerr black holes. The time scale of the resonant oscillation in a rapidly rotating black hole, in which case the horizon radius becomes small, is characterized by $\left(\mathrm{black}\mathrm{}\mathrm{hole}\mathrm{}\mathrm{mass}{)}^{1/2}\right(\mathrm{Planck}\mathrm{}\mathrm{mass}{)}^{-3/2}$ rather than the light-crossing time of the horizon.

Following the work of Kinnersley and Walker for flat spacetimes, we analyzed the anti–de Sitter C metric in a previous paper. In this paper we study the de Sitter C metric (dS C metric). The C metric with a generic cosmological constant and other extra parameters was introduced by Plebański and Demiański. When one then sets to zero some of the extra parameters, and works with a positive cosmological constant, one has the dS C metric which has been analyzed and physically interpreted by Podolský and Griffiths. It describes a pair of accelerated black holes in the dS background with the acceleration being provided (in addition to the cosmological constant) by a strut that pushes away the two black holes or, alternatively, by a string that pulls them. We extend their analysis mainly in four directions. First, we draw the Carter-Penrose diagrams of the massless uncharged dS C metric, of the massive uncharged dS C metric and of the massive charged dS C metric. These diagrams allow us to clearly identify the presence of two dS black holes and to conclude that they cannot interact gravitationally. Second, we reexamine the embedding of the dS C metric in the 5D Minkowski spacetime and we represent the motion of the dS C metric origin in the dS 4-hyperboloid as well as the localization of the strut. Third, we comment on the physical properties of the strut that connects the two black holes. Finally, we find the range of parameters that correspond to nonextreme black holes, extreme black holes, and naked particles.

We follow our previous paper on the possible cosmological variation of the weak scale (quark masses) and the strong scale, inspired by data on the cosmological variation of the electromagnetic fine structure constant from distant quasar absorption spectra. In this work we identify the strange quark mass $m_s$ as the most important quantity, and the sigma meson mass as the ingredient of the nuclear forces most sensitive to it. As a result, we claim significantly stronger limits on the ratio of weak/strong scale ${(W=m}_s/{\Lambda }_{\mathrm{QCD}})$ variation following from our previous discussion on primordial big-bang nucleosynthesis $(|\delta W/W|<0.006)$ and the Oklo natural nuclear reactor $[|\delta W/W|<1.2\mathrm{}\times {10}^{-10};$ there is also a nonzero solution $\delta W/W=(-0.56\pm 0.05)\times {10}^{-9}].$

The stability of a Fermi ball $(F$ ball), which is a kind of nontopological soliton accompanying the breakdown of the approximate $Z_2$ symmetry, is investigated in three situations: when it is electrically neutral, when it is electrically charged and unscreened, and when it is electrically charged and screened. We argue only that the third case is physically meaningful since the neutral F ball is unstable and the case of an unscreened charged F ball is observationally excluded when it has a sizable contribution to CDM. We find that the energy scale of the breakdown of the approximate $Z_2$ symmetry $v$ should satisfy $v<\mathrm{}3\mathrm{}\times {10}^6\mathrm{GeV}$ if the F ball is the main component of CDM.

For a generic quantum field theory we study the role played by the renormalization-group (RG) running of the cosmological constant (CC) in determining the ultimate fate of the universe. We consider the running of the CC of generic origin (the vacuum energy of quantum fields and the potential energy of classical fields), with the RG scale proportional to the (total energy ${\mathrm{d}\mathrm{e}\mathrm{n}\mathrm{s}\mathrm{i}\mathrm{t}\mathrm{y})}^{1/4}$ as the most obvious identification. Starting from the present-era values for cosmological parameters we demonstrate how the running can easily provide a negative cosmological constant, thereby changing the fate of the universe, at the same time rendering compatibility with critical string theory. We also briefly discuss the recent past in our scenario.

We explore the applications of the maximum entropy method (MEM) to determine the properties of unstable particles using the four-dimensional $O\left(4\right)\mathrm{}{\phi }^4$ theory as a laboratory. The spectral function of the correlation function of the unstable $\sigma$ particle is calculated with the MEM and is shown to yield reliable results for both the mass of the $\sigma$ and the energy of the two-pion state. Calculations are also made for the case in which $\sigma$ is stable. The distinctive differences in the volume dependence of the $\sigma$ mass and two-pion energy for the stable and unstable cases are analyzed in terms of perturbation theory.

The present unitarity triangle fit, whose essential input is represented by the $\overrightarrow{s}d$ and $\overrightarrow{b}d$ transition processes, fully agrees with the SM. However, most of the phenomena involving $\overrightarrow{b}s$ transitions are still largely unexplored and hence $\overrightarrow{b}s$ phenomenology still constitutes a place for new physics manifestations, in spite of the tremendous experimental and theoretical progress on $\overrightarrow{B}{X}_s\gamma .$ We perform a systematic study of the $\mathrm{CP}$ conserving and violating supersymmetry (SUSY) contributions to $\overrightarrow{b}s$ processes in a generic minimal supersymmetric standard model (MSSM). We consider gluino exchange contributions including next-to-leading order QCD corrections and lattice hadronic matrix elements for $\Delta B=2\mathrm{}$ and $\Delta B=1\mathrm{}$ processes. We take into account all available experimental information on processes involving $\overrightarrow{b}s$ transitions $(\overrightarrow{B}{X}_s\gamma ,\overrightarrow{B}{X}_s{\mathcal{l}}^{+}{\mathcal{l}}^{-}$ and the lower bound on the $B_s-B_s$ mass difference $\Delta M_s).\mathrm{}$ We study the correlations among the relevant observables under scrutiny at present or in a not too far future: $\Delta M_s$ and the amount of $\mathrm{CP}$ violation in $\overrightarrow{B}\phi K_s,B_s\to J/\psi \phi ,\overrightarrow{B}{X}_s\gamma .$ In particular we discuss the recent data by BaBar and BELLE on the time-dependent $\mathrm{CP}$ asymmetry in the decay $\overrightarrow{B}\phi K_S$ which suggest a deviation from the SM expectation. Our results show that the processes involving $\overrightarrow{b}s$ transitions represent a splendid opportunity to constrain different MSSM realizations, and, even more important, that they offer concrete prospects to exhibit SUSY signals at B factories and hadron colliders in spite of all the past frustration in flavor changing neutral current searches of new physics hints.

We show how the problem of small neutrino masses and suppressed proton decay can be simultaneously resolved in 6D universal extra dimension models (UED’s) with a low fundamental scale using extended gauge groups that contain the local $B-L$ symmetry. The extra space dimensions are compactified either on a $T^2{/Z}_2$ or $T^2{/Z}_2\times Z_2^{\prime }$ orbifold depending on whether the full gauge group is ${\mathrm{SU}\left(2\right)\mathrm{}}_L\times {U\left(1\right)\mathrm{}}_{I_{3R}}\times {U\left(1\right)\mathrm{}}_{B-L}$ or ${\mathrm{SU}\left(2\right)\mathrm{}}_L\times {\mathrm{SU}\left(2\right)\mathrm{}}_R\times {U\left(1\right)\mathrm{}}_{B-L}.$ In both cases, neutrino masses are suppressed by an appropriate orbifold parity assignment for the standard model singlet neutrinos and the proton decay rate is suppressed due to a residual discrete symmetry left over from compactification. For lower values of the fundamental scale, a dominant decay mode of the neutron is $\overrightarrow{n}3\nu .$ An interesting consequence of the model is a possible two component picture for the dark matter of the universe.