Long base interferometers for gravitational wave detection involve a number of mirrors having outstanding levels of quality. These large mirrors are now currently being produced. Each mirror has its own signature in reflected wave fronts due to its particular roughness pattern. Direct wave front measurements, carried out after the coating process, provide numerical maps from which very useful information can be extracted, either directly or by insertion in a numerical model of the interferometer. In particular, we show how it is possible to test the performances of the instrument for various attitudes of the mirrors before installing them in the vacuum chambers, a heavy and dangerous task.

We calculate the Wilson coefficients $C_{10}{,C}_{Q_i}$ $\mathrm{}(i=1,2\mathrm{})\mathrm{}$ in the $\overline{\mathrm{MS}}$ renormalization scheme in the model III two Higgs doublet model (2HDM). Using the obtained Wilson coefficients, we analyze the CP violation in the decays $B_q^0\to l^{+}{l}^{-}\mathrm{}(q=d,s)\mathrm{}$ in the model. The CP asymmetry $A_{\mathrm{CP}},$ depending on the parameters of the models, can be as large as 40% and 35% in $B_d\to l^{+}{l}^{-}$ for $l=\tau$ and $l=\mu ,$ respectively. It can reach 4% for $B_s^0$ decays. Because in the SM CP violation is smaller than or equal to ${O(10\mathrm{}}^{-3}),$ which is unobservably small, an observation of CP asymmetry in the decays $B_q^0\to l^{+}{l}^{-}\mathrm{}(q=d,s)\mathrm{}$ would unambiguously signal the existence of new physics.

We examine localized kinetic terms for gauge fields which can propagate into compact, warped extra dimensions. We show that these terms can have a relevant impact on the values of the Kaluza-Klein (KK) gauge field masses, wave functions, and couplings to brane and bulk matter. The resulting phenomenological implications are discussed. In particular, we show that the presence of opaque branes, with nonvanishing brane-localized gauge kinetic terms, allow much lower values of the lightest KK mode than in the case of transparent branes. Moreover, we show that if the large discrepancies among the different determinations of the weak mixing angle would be solved in favor of the value obtained from the lepton asymmetries, bulk electroweak gauge fields in warped-extra dimensions may lead to an improvement of the agreement of the fit to the electroweak precision data for a Higgs boson mass of the order of the weak scale and a mass of the first KK gauge boson excitation of a few TeV, most likely within reach of the CERN LHC.

In this paper we study the effects of $\overrightarrow{s}d+2\mathrm{}$ gluon on $K_L\to \gamma \gamma$ in the standard model. We find that this interaction can induce new sizable SU(3) and U(3) nonet breaking effects in $K_L-\eta ,{\eta }^{\prime }$ transitions and therefore in $K_L\to \gamma \gamma$ due to large matrix elements of $〈\eta \left({\eta }^{\prime }\right)|{\alpha }_s{G}_{\mu \nu }^a{G}_a^{\mu \nu }|0〉$ from the QCD anomaly. These new effects play an important role in explaining the observed value. We also study the effects of this interaction on the contribution to $\Delta m_{K_L-K_S}.$

Within the framework of the top-color-assisted technicolor (TC2) model, we calculate the new physics contributions to the branching ratios $\mathcal{B}{(B}_{s,d}\to \gamma \gamma )$ and $\mathrm{CP}$ violating asymmetries $r_{\mathrm{CP}}^{-}{(B}_{s,d}\to \gamma \gamma )$ in the QCD factorization based on the heavy-quark limit $m_b\gg {\Lambda }_{\mathrm{QCD}}.$ Using the considered parameter space, we find that (a) for both $B_s\to \gamma \gamma$ and $B_d\to \gamma \gamma$ decays, the new physics contribution can provide a factor of two to six enhancement to their branching ratios, (b) for the $B_s\to \gamma \gamma$ decay, its direct $\mathrm{CP}$ violation is very small in both the SM and TC2 model, and (c) the $\mathrm{CP}$ violating asymmetry $r_{\mathrm{CP}}^{-}{(B}_d\to \gamma \gamma )$ is around the ten percent level in both the SM and TC2 model, but the sign of $\mathrm{CP}$ asymmetry in the TC2 model is different from that in the SM.

The coupled system of renormalized Dyson-Schwinger equations for the quark, gluon, and ghost propagators of the Landau gauge QCD is solved within truncation schemes. These employ bare as well as nonperturbative Ansätze for the vertices such that the running coupling as well as the quark mass function are independent of the renormalization point. The one-loop anomalous dimensions of all propagators are reproduced. Dynamical chiral symmetry breaking is found; the dynamically generated quark mass agrees well with the phenomenological values, and the corresponding results from lattice calculations. The effects of unquenching the system are small. In particular the infrared behavior of the ghost and gluon dressing functions found in previous studies is almost unchanged as long as the number of light flavors is smaller than four.

We review the status of ${\nu }_{\mu }\to {\nu }_{\tau }$ flavor transitions of atmospheric neutrinos in the 92 kton-year data sample collected in the first phase of the Super-Kamiokande (SK) experiment, in combination with the recent spectral data from the KEK-to-Kamioka (K2K) accelerator experiment (including 29 single-ring muon events). We consider a theoretical framework which embeds flavor oscillations plus hypothetical decoherence effects, and where both standard oscillations and pure decoherence represent limiting cases. It is found that standard oscillations provide the best description of the SK+K2K data, and that the associated mass-mixing parameters are determined at $\pm 1\sigma$ (and $N_{\mathrm{DF}}=1)$ as $\Delta m^2=(2.6\mathrm{}\pm 0.4)\times {10}^{-3}{\mathrm{eV}}^2$ and ${\sin }^{2}2\theta {=1.00\mathrm{}}_{-0.05}^{+0.00\mathrm{}}.$ As compared with standard oscillations, the case of pure decoherence is disfavored, although it cannot be ruled out yet. In the general case, additional decoherence effects in the ${\nu }_{\mu }\to {\nu }_{\tau }$ channel do not improve the fit to the SK and K2K data, and upper bounds can be placed on the associated decoherence parameter. Such indications, presently dominated by SK, could be strengthened by further K2K data, provided that the current spectral features are confirmed with higher statistics. A detailed description of the statistical analysis of SK and K2K data is also given, using the so-called “pull” approach to systematic uncertainties.

The expression for the dynamical mass of fermions in QED in a magnetic field is obtained for a large number of the fermion flavor N in the framework of $1/N$ expansion. The existence of a threshold value $N_{\mathrm{thr}},$ dividing the theories with essentially different dynamics, is established. For the number of flavors $N\ll N_{\mathrm{thr}},$ the dynamical mass is very sensitive to the value of the coupling constant ${\alpha }_b,$ related to the magnetic scale $\mu =\sqrt{|\mathrm{eB}|}.$ For N of the order of $N_{\mathrm{thr}}$ or larger, a dynamics similar to that in the Nambu–Jona-Lasinio model with a cutoff of the order of $\sqrt{|\mathrm{eB}|}$ and the dimensional coupling constant $G\sim 1/\left(N|\mathrm{eB}|\right)$ takes place. In this case, the value of the dynamical mass is essentially ${\alpha }_b$ independent (the dynamics with an infrared stable fixed point). The value of $N_{\mathrm{thr}}$ separates a weak coupling dynamics (with ${\tilde{\alpha }}_b\equiv N{\alpha }_b\ll 1)$ from a strong coupling one (with ${\tilde{\alpha }}_b\gtrsim 1)$ and is of the order of $1/{\alpha }_b.$

For a quantum mechanical system with broken supersymmetry, we present a simple method of determining the ground state when the corresponding energy eigenvalue is sufficiently small. A concise formula is derived for the approximate ground-state energy in an associated, well-separated, asymmetric double-well-type potential. Our discussion is also relevant for the analysis of the fermion bound state in the kink-antikink scalar background.

A partial wave analysis using the basis of the total angular momentum operator $J_3$ is carried out for the first order Born amplitude of a Dirac particle in an Aharonov-Bohm potential. It is demonstrated that the s partial wave contributes to the scattering amplitude in contrast with the case with scalar nonrelativistic particles. We suggest that this explains the fact that the first order Born amplitude of a Dirac particle coincides with the exact amplitude expanded to the same order, where it does not for a scalar particle. An interesting algebra involving the Dirac velocity operator and the angular observables is discovered and its consequences are exploited.

Using nonrelativistic many body quantum field theory, a master equation is derived for the reduced density matrix of a dilute gas of massive particles undergoing scattering interactions with an environment of light particles. The dynamical variable that naturally decoheres (the pointer basis) is essentially the local number density of the dilute gas. Earlier master equations for this sort of system (such as that derived by Joos and Zeh) are recovered on restricting to the one-particle sector for the distinguished system. The derivation shows explicitly that the scattering environment stores information about the system by “measuring” the number density. This therefore provides an important example of the general connection between decoherence and records indicated by the decoherent histories approach to quantum theory. It also brings the master equation for this system into a form emphasizing the role of local densities, which is relevant to current work in deriving hydrodynamic equations from quantum theory.

We show that the Kidder-Scheel-Teukolsky family of hyperbolic formulations of the 3+1 evolution equations of general relativity remains hyperbolic when coupled to a recently proposed modified version of the Bona-Masso slicing condition.

We present a model independent determination of the CMB from any kind of fluid that has an equation of state taking four different values. The first region has $w=1/3,$ the second $w=1,$ the third $w=-1$ while the last one has $-1<~w=cte<~-2/3.$ This kind of dynamical w contains as a limit the cosmological constant and tracker models. We derive the model independent evolution of $w_{\phi },$ for scalar fields, and we see that it remains most of the time in either of its three extremal values given by $w_{\phi }=1,-{1,w}_{\phi o}.$ This “varying” w is the generic behavior of scalar fields, quintessence, and we determine the size of the different regions by solving the dynamical equations in a model independent way. The dynamical w models have a better fit to CMB data then the cosmological constant and the tracker models. These models can be thought of as arising after a late time phase transition ${\Lambda }_c$ where the scalar potential is produced. Before this time all the fields in this sector were massless and redshifted as radiation, giving the first period $w=1/3.\mathrm{}$ We determine the effect on the CMB of having the first two regions $w=1/3,1\mathrm{}$ and show that it is not negligible. In general, the CMB spectrum sets a lower limit on the phase transition scale ${\Lambda }_c.$ For smaller ${\Lambda }_c$ the CMB peaks are moved to the right of the spectrum and the height increases considerably. Depending on the initial energy density we obtain a lower limit on the phase transition scale ${\Lambda }_c,$ when the scalar field appears and we have the transition from $w=1/3\mathrm{}$ to $w=1.\mathrm{}$ For ${\Omega }_{\phi i}=0.1\mathrm{}$ the CMB sets a lower limit on the phase transition scale ${\Lambda }_c>~0.2\mathrm{eV}.$ This work allows for the possibility of distinguishing the nature of dark energy.

We carry out a numerical calculation of ultrahigh energy neutrino propagation through the Earth, taking into account the neutrino regeneration process in both neutral current and charged current neutrino interactions. The attenuation of neutrinos traversing the Earth (shadow effect) is determined, and the fluxes of $\nu$-induced upward-going leptons (muon and tau) are obtained at the Earth’s surface and for two configurations of the neutrino flavor in the incident neutrino flux $({\nu }_{\mu }\to {\nu }_{\tau }$ mixing). The implications of these results are discussed in the context of the possibility of detection of $\nu$-induced leptons in the next round of fluorescent telescopes such as the AUGER detector.

We consider the chargino contribution to $\mathrm{CP}$ violation in $\overrightarrow{B}\phi K_S$ decay in the minimal supersymmetric standard model at large $\tan \beta .$ It is shown that the Wilson coefficient $C_{8g}$ of the chromomagnetic penguin operator can be significantly enhanced by the chargino-mediated diagrams while satisfying other direct or indirect experimental constraints. The enhanced $C_{8g}$ allows a large deviation in the $\mathrm{CP}$ asymmetry from the standard model prediction, especially it can explain the apparent anomaly reported by BaBar and Belle.

We try a global fit of the experimental branching ratios and $\mathrm{CP}$ asymmetries of the charmless $\overrightarrow{B}\mathrm{PV}$ decays according to QCD factorization. We find it impossible to reach satisfactory agreement, the confidence level (C.L.) of the best fit being smaller than 0.1%. The main reason for this failure is the difficulty to accommodate several large experimental branching ratios of the strange channels. Furthermore, experiment was not able to exclude a large direct $\mathrm{CP}$ asymmetry in $\to {\rho }^{+}{\pi }^{-},$ which is predicted to be very small by QCD factorization. Trying a fit with QCD factorization complemented by a charming-penguin-diagram-inspired model we reach a best fit which is not excluded by experiment (C.L. of about 8%) but is not fully convincing. These negative results must be tempered by the remark that some of the experimental data used are recent and might still evolve significantly.

Starting from $N=1\mathrm{}$ scalar and vector supermultiplets in 2+1 dimensions, we construct superfields which constitute Lagrangians invariant under $N=2\mathrm{}$ supersymmetries. We first recover the $N=2\mathrm{}$ supersymmetric Abelian-Higgs model and then the $N=2\mathrm{}$ pure super Yang-Mills model. The conditions for this elevation are consistent with previous results found by other authors.

We implement in systems of fermions the formalism of pseudoclassical paths that we recently developed for systems of bosons and show that quantum states of fermionic fields can be described, in the Heisenberg picture, as linear combinations of randomly distributed paths that do not interfere between themselves and obey classical Dirac equations. Every physical observable is assigned a time-dependent value on each path in a way that respects the anticommutative algebra between quantum operators, and we observe that these values on paths do not necessarily satisfy the usual algebraic relations between classical observables. We use these pseudoclassical paths to define the dynamics of quantum fluctuations in systems of fermions and show that, as we found for systems of bosons, the dynamics of fluctuations of a wide class of observables that we call “collective” observables can be approximately described in terms of classical stochastic concepts. Finally, we apply this formalism to describe the dynamics of local fluctuations of globally conserved fermion numbers.

We study a modified Yang-Mills-Higgs system coupled to Einstein gravity. The modification of the Einstein-Hilbert action involves the direct coupling of the Higgs field to the scalar curvature. In this modified system we are able to write a Bogomol’nyi type condition in curved space and demonstrate that the positive static energy functional is bounded from below. We then investigate non-Abelian spherically symmetric static solutions in a similar fashion to the ’t Hooft–Polyakov monopole. After reviewing previously studied monopole solutions of this type, we extend the formalism to include electric charge and we present dyon solutions.

We consider a two-dimensional noncommutative inverted oscillator in the presence of a constant magnetic field, coupled to the system in a “symplectic” and “Poisson” way. We show that it has a discrete energy spectrum for some value of the magnetic field.