The spherically symmetric steady accretion of polytropic perfect fluids onto a black hole is the simplest flow model that can demonstrate the effects of backreaction. The analytic and numerical investigation reveals that backreaction keeps intact most of the characteristics of the sonic point. For any such system, with the free parameter being the relative abundance of the fluid, the mass accretion rate achieves maximal value when the mass of the fluid is $1/3$ of the total mass. Fixing the total mass of the system, one observes the existence of two weakly accreting regimes, one overabundant and the other poor in fluid content.

We develop several nonperturbative approximations for studying the dynamics of a supersymmetric $O(N)$ model which preserve supersymmetry. We study the phase structure of the vacuum in both the leading order in large-$N$ approximation as well as in the Hartree approximation, and derive the finite temperature renormalized effective potential. We derive the exact Schwinger-Dyson equations for the superfield Green functions and develop the machinery for going beyond the next to leading order in large-$N$ approximation using a truncation of these equations which can also be derived from a two-particle irreducible effective action.

We calculate the likelihood map in the full 7-dimensional parameter space of the minimal supersymmetric standard model assuming universal boundary conditions on the supersymmetry breaking terms. Simultaneous variations of $m_0$, $A_0$, $M_{1/2}$, $\tan \beta$, $m_t$, $m_b$ and ${\alpha }_s(M_Z)$ are applied using a Markov chain Monte Carlo algorithm. We use measurements of $b\to s\gamma$, $(g-2{)}_{\mu }$ and ${\Omega }_{DM}{h}^2$ in order to constrain the model. We present likelihood distributions for some of the sparticle masses, for the branching ratio of $B_s^0\to {\mu }^{+}{\mu }^{-}$ and for $m_{\tilde{\tau }}-m_{{\chi }_1^0}$. An upper limit of $2\times {10}^{-8}$ on this branching ratio might be achieved at the Tevatron, and would rule out $29\%$ of the currently allowed likelihood. If one allows for non-thermal-neutralino components of dark matter, this fraction becomes $35\%$. The mass ordering allows the important cascade decay ${\tilde{q}}_L\to {\chi }_2^0\to {\tilde{l}}_R\to {\chi }_1^0$ with a likelihood of $24\pm 4\%$. The stop-coannihilation region is highly disfavored, whereas the light Higgs region is marginally disfavored.

We incorporate heavy-light mesons into staggered chiral perturbation theory ($\mathrm{S}\chi \mathrm{PT}$), working to leading order in $1/m_Q$, where $m_Q$ is the heavy-quark mass. At first nontrivial order in the chiral expansion, staggered taste violations affect the chiral logarithms for heavy-light quantities only through the light-meson propagators in loops. There are also new analytic contributions coming from additional terms in the Lagrangian involving heavy-light and light mesons. Using this heavy-light $\mathrm{S}\chi \mathrm{PT}$, we perform the one-loop calculation of the $B$ (or $D$) meson leptonic decay constant in the partially quenched and full QCD cases. In our treatment, we assume the validity both of the “fourth root trick” to reduce four staggered tastes to one, and of the $\mathrm{S}\chi \mathrm{PT}$ prescription to represent this trick by insertions of factors of $1/4$ for each sea-quark loop.

We present a seminumerical algorithm to calculate one-loop virtual corrections to scattering amplitudes. The divergences of the loop amplitudes are regulated using dimensional regularization. We only treat in detail the case of amplitudes with up to five external legs and massless internal lines, although we believe the method to be more generally applicable. Tensor integrals are reduced to generalized scalar integrals, which in turn are reduced to a set of known basis integrals using recursion relations. The reduction algorithm is modified near exceptional configurations to ensure numerical stability. To test the procedure we apply these techniques to one-loop corrections to the Higgs to four quark process for which analytic results have recently become available.

We review the experimental status of the $b$-quark production at the Fermilab Tevatron. We compare all available measurements to perturbative QCD predictions (NLO and FONLL) and also to the parton-level cross section evaluated with parton-shower Monte Carlo generators. We examine both the single $b$ cross section and the so called $b\overline{b}$ correlations. The review shows that the experimental situation is quite complicated because the measurements appear to be inconsistent among themselves. In this situation, there is no solid basis to either claim that perturbative QCD is challenged by these measurements or, in contrast, that long-standing discrepancies between data and theory have been resolved by incrementally improving the measurements and the theoretical prediction.

We address known discrepancies between the heavy-flavor properties of jets produced at the Tevatron collider and the prediction of conventional-QCD simulations. In this study, we entertain the possibility that these effects are real and due to new physics. We show that all anomalies can be simultaneously fitted by postulating the additional pair production of light bottom squarks with a 100% semileptonic branching fraction.

In this work, we calculate the branching ratios, polarization fractions and $CP$ asymmetry parameters of decay modes $B\to \rho (\omega )\rho (\omega )$ in the perturbative QCD approach, which is based on ${\mathbf{k}}_T$ factorization. After calculation, we find that the branching ratios of $B^0\to {\rho }^{+}{\rho }^{-}$, $B^{+}\to {\rho }^{+}{\rho }^0$, and $B^{+}\to {\rho }^{+}\omega$ are at the order of ${10}^{-5}$, and their longitudinal polarization fractions are more than 90%. The above results agree with BaBar’s measurements. We also calculate the branching ratios and polarization fractions of $B^0\to {\rho }^0{\rho }^0$, $B^0\to {\rho }^0\omega$, and $B^0\to \omega \omega$ decays. We find that their longitudinal polarization fractions are suppressed to 60–80% due to a small color suppressed tree contribution. The dominant penguin and nonfactorization tree contributions equally contribute to the longitudinal and transverse polarization, which will be tested in the future experiments. We predict the $CP$ asymmetry of $B^0\to {\rho }^{+}{\rho }^{-}$ and $B^{+}\to {\rho }^{+}{\rho }^0$, which will be measured in $B$ factories.

I explore the hypothesis that the Cabibbo angle is an expansion parameter for lepton as well as quark mixing. Cabibbo effects are deviations from zero mixing for the quarks but are deviations from unknown mixings for the leptons, such that lepton mixing is veiled by a Cabibbo haze. I present a systematic classification of parametrizations and catalog the leading order effects. This phenomenological approach has practical merit both as a method for organizing top-down flavor models and as a guideline for planning future experiments.

The sizes of tracks of events of neutrinoless double-beta decay in a Germanium detector depend on particle physics and nuclear physics parameters such as neutrino mass, right-handed current parameters, etc., and nuclear matrix elements. In this paper for the first time Monte Carlo simulations of neutrino-accompanied ($2\nu \beta \beta$) and neutrinoless double-beta decay ($0\nu \beta \beta$) events, and of various kinds of background processes such as multiple and other $\gamma$ interactions are reported for a Ge detector. The time history of the evolution of the individual events is followed and the sizes of the events (partial volumes in the detector inside which the energy of the event is released) are investigated. Effects of the angular correlations of the two electrons in $\beta \beta$ decay, which again depend on the above nuclear and (for $0\nu \beta \beta$ decay) on particle physics parameters, are taken into account and have been calculated for this purpose for the first time on basis of the experimental half-life of ${}^{76}\mathrm{G}\mathrm{e}$ and of realistic nuclear matrix elements. The sizes determine, together with the location of the events in the detector, the pulse shapes to be observed. It is shown for $\beta \beta$ decay of ${}^{76}\mathrm{G}\mathrm{e}$, that $\beta \beta$ events should be selectable with high efficiency by rejecting large size (high multiplicity) $\gamma$ events. Double-escape peaks of similar energy of $\gamma$ lines show concerning their sizes similar behavior as $0\nu \beta \beta$ events, and in that sense can be of some use for corresponding ’calibration’ of pulse shapes of the detector. The possibility to distinguish $\beta \beta$ events from $\gamma$ events is found to be essentially independent of the particle physics parameters of the $0\nu \beta \beta$ process. A brief outlook is given on the potential of future experiments with respect to determination of the particle physics parameters $⟨m_{\nu }⟩,⟨\lambda ⟩,⟨\eta ⟩$.

The $e^{+}{e}^{-}\to p\overline{p}$ cross section is determined over a range of $p\overline{p}$ masses, from threshold to $4.5\mathrm{GeV}/c^2$, by studying the $e^{+}{e}^{-}\to p\overline{p}\gamma$ process. The data set corresponds to an integrated luminosity of $232{\mathrm{fb}}^{-1}$, collected with the BABAR detector at the PEP-II storage ring, at an $e^{+}{e}^{-}$ center-of-mass energy of 10.6 GeV. The mass dependence of the ratio of electric and magnetic form factors, $|G_E/G_M|$, is measured for $p\overline{p}$ masses below $3\mathrm{GeV}/c^2$; its value is found to be significantly larger than 1 for masses up to $2.2\mathrm{GeV}/c^2$. We also measure $J/\psi \to p\overline{p}$ and $\psi (2S)\to p\overline{p}$ branching fractions and set an upper limit on $Y(4260)\to p\overline{p}$ production and decay.

A quark action designed for highly anisotropic-lattice simulations is discussed. The mass-dependence of the parameters in the action is studied and the results are presented. Applications of this action in studies of heavy quark quantities are described and results are presented from simulations at an anisotropy of six, for a range of quark masses from strange to bottom.

From a study of conserved quantities of the so-called modified Newtonian dynamics we propose an alternative to this theory. We show that this proposal is consistent with the Tully-Fisher law, has conserved quantities whose Newtonian limit are the energy and angular momentum, and can be useful to explain cosmic acceleration. The dynamics obtained suggests that, when acceleration is very small, time depends on acceleration. This result is analogous to that of special relativity where time depends on velocity.

We consider inflationary cosmology in the context of string compactifications with multiple throats. In scenarios where the warping differs significantly between throats, string and Kaluza-Klein physics can generate potentially observable corrections to the cosmology of inflation and reheating. First we demonstrate that a very low string scale in the ground state compactification is incompatible with a high Hubble scale during inflation, and we propose that the compactification geometry is altered during inflation. In this configuration, the lowest scale is just above the Hubble scale, which is compatible with the effective field theory but still leads to potentially observable cosmic microwave background corrections. Also in the appropriate region of parameter space, we find that reheating leads to a phase of long open strings in the standard model sector (before the usual radiation-dominated phase). We sketch the cosmology of the long string phase and we discuss possible observational consequences.

It is sometimes stated in the literature that the quantum anomaly is regarded as an example of the geometric phase. Though there is some superficial similarity between these two notions, I here show that the differences between these two notions are more profound and fundamental. As an explicit example, I analyze in detail a quantum mechanical model proposed by M. Stone, which is supposed to show the above connection. I show that the geometric term in the model, which is topologically trivial for any finite time interval $T$, corresponds to the so-called “normal naive term” in field theory and has nothing to do with the anomaly-induced Wess-Zumino term. In the fundamental level, the difference between the two notions is stated as follows: The topology of gauge fields leads to level crossing in the fermionic sector in the case of chiral anomaly, and the failure of the adiabatic approximation is essential in the analysis, whereas the (potential) level crossing in the matter sector leads to the topology of the Berry phase only when the precise adiabatic approximation holds.

We derive the first law of black ring thermodynamics in $n$-dimensional Einstein dilaton gravity with additional $(p+1)$-form field strength being the simplest generalization of five-dimensional theory containing a stationary black ring solution with dipole charge. It was done by means of choosing any cross section of the event horizon to the future of the bifurcation surface.

The possibility that neutron stars may contain substantial hyperon populations has important implications for neutron-star cooling and, through bulk viscosity, the viability of the $r$-modes of accreting neutron stars as sources of persistent gravitational waves. In conjunction with laboratory measurements of hypernuclei, astronomical observations were used by Glendenning and Moszkowski [Phys. Rev. Lett. 67, 2414 (1991)] to constrain the properties of hyperonic equations of state within the framework of relativistic mean-field theory. We revisit the problem, incorporating recent measurements of high neutron-star masses and a gravitational redshift. We find that only the stiffest of the relativistic hyperonic equations of state commonly used in the literature is compatible with the redshift. However, it is possible to construct stiffer equations of state within the same framework which produce the observed redshift while satisfying the experimental constraints on hypernuclei, and we do this. The stiffness parameter that most affects the redshift is not the incompressibility but rather the hyperon coupling. Nonrelativistic potential-based equations of state with hyperons are not constrained by the redshift, primarily due to a smaller stellar radius.

Current advances in observational cosmology suggest that our Universe is flat and dominated by dark energy. Out of many particular models of dark energy present in the literature we focus on four: quintessence, quintessence with time varying equation of state, braneworld model and generalized Chaplygin gas model. In this paper we discuss the utility of strong lensing systems for providing additional constraints on dark energy models. In particular, we use an Einstein cross gravitational lensing system HST $14176+5226$ to confront its measured characteristics with background cosmologies invoked in the context of dark energy. The image separations in the system depend on angular distances to the lens and to the source, which in turn are determined by background cosmology. This opens a possibility to constrain cosmological model provided that we have good knowledge of the lens model. We demonstrate that recent measurements of velocity dispersion in the lensing galaxy made by Subaru telescope seem to be consistent with independently obtained bounds on parameters of cosmological models considered. The method we describe is based on angular diameter distances and could become a valuable tool of cosmological model inference complementary to Hubble diagram technique based on luminosity distance.

A highly non-Gaussian cosmological perturbation with a flat spectrum has unusual stochastic properties. We show that they depend on the size of the box within which the perturbation is defined, but that for a typical observer the parameters defining the perturbation “run“ to compensate for any change in the box size. Focusing on the primordial curvature perturbation, we show that an uncorrelated Gaussian-squared component is bounded at around the 10% level by the Wilkinson Microwave Anisotropy Probe (WMAP) bound on the bispectrum, and we show that a competitive bound may follow from the trispectrum when it too is bounded by WMAP. Similar considerations apply to a highly non-Gaussian isocurvature perturbation.

We present the next-to-leading-order QCD corrected total cross sections and the distributions of the transverse momenta of the final anti-bottom quark, top quark, and charged Higgs boson for the processes of $p\overline{p}/pp\to t\overline{b}{H}^{-}+X$ in the minimal supersymmetric standard model at Tevatron and CERN LHC. We find that the next-to-leading-order (NLO) QCD corrections significantly modify the leading-order distributions of the transverse momenta of final particles ($p_T^b$, $p_T^t$, and $p_T^{H^{-}}$), and the total NLO QCD corrections reduce the dependence of the cross section on the renormalization and factorization scales; in particular, the NLO QCD corrected cross sections at the LHC are nearly independent of these scales. Our results show that the relative correction is obviously related to $m_{H^{-}}$ and $\tan \beta$, and the total NLO QCD relative corrections can be beyond $-50\%$ at Tevatron and approach $-40\%$ at the LHC in our chosen parameter space.