The possibility of a strongly first-order electroweak phase transition by means of a dimension-six Higgs operator in the Higgs potential of the standard model is studied at finite temperature at the one-loop level. Exact calculation of the one-loop effective Higgs potential at finite temperature suggests that for the Higgs boson with its mass between 115 and 132 GeV the strongly first-order electroweak phase transition is possible if a dimension-six operator is present.

Determinations of $|V_{ud}|$ and $|V_{us}|$ along with their implications for the unitarity test $|V_{ud}{|}^2+|V_{us}{|}^2+|V_{ub}{|}^2=1$ are discussed. The leading two-loop radiative corrections to neutron $\beta$ decay are evaluated and used to derive a refined relationship $|V_{ud}{|}^2{\tau }_n(1+3g_A^2)=4908(4)\mathrm{s}$. Employing $|V_{ud}|=0.9740(5)$ from superallowed nuclear decays and the measured neutron lifetime ${\tau }_n=885.7(7)\mathrm{s}$ leads to the precise prediction $g_A=1.2703(8)$ which is compared with current direct experimental values. Various extractions of $|V_{us}|$ are described and updated. The long accepted Particle Data Group value of $|V_{us}|$ from fitted $K_{e3}$ decay rates suggests a deviation from CKM unitarity but it is contradicted by more recent experimental results which confirm unitarity with good precision. An outlook for possible future advances is given.

The measurement of the deviation of the 2–3 leptonic mixing from maximal, $D_{23}\equiv 1/2-{sin}^2{\theta }_{23}$, is one of the key issues for understanding the origin of the neutrino masses and mixing. In the $3\nu$ context we study the dependence of various observables in the atmospheric neutrinos on $D_{23}$. We perform the global $3\nu$-analysis of the atmospheric and reactor neutrino data taking into account the effects of both the oscillations driven by the solar parameters ($\Delta m_{21}^2$ and ${\theta }_{12}$) and the 1–3 mixing. The departure from the one-dominant mass scale approximation results into the shift of the 2–3 mixing from maximal by $\Delta {sin}^2{\theta }_{23}\approx 0.04$, so that $D_{23}\sim 0.04\pm 0.07$ $(1\sigma )$. Though the value of the shift is not statistically significant, the tendency of the allowed region to move towards smaller values of ${sin}^2{\theta }_{23}$ is robust. The shift is induced by the excess of the $e$-like events in the sub-GeV sample. We show that future large scale water Cherenkov detectors can determine $D_{23}$ with accuracy of a few percent, comparable with the sensitivity of future long-baseline experiments. Moreover, the atmospheric neutrinos will provide unique information on the sign of the deviation (octant of ${\theta }_{23}$).

The polarization of the ${\chi }_{c2}$ produced in $\psi (2S)$ decays into $\gamma {\chi }_{c2}$ is measured using a sample of $14\times {10}^6\psi (2S)$ events collected by the BESII detector at the BEPC storage ring. A fit to the ${\chi }_{c2}$ production and decay angular distributions in $\psi (2S)\to \gamma {\chi }_{c2}$, ${\chi }_{c2}\to {\pi }^{+}{\pi }^{-}$ and $K^{+}{K}^{-}$ yields values $x=A_1/A_0=2.08\pm 0.44$ and $y=A_2/A_0=3.03\pm 0.66$, with a correlation $\rho =0.92$ between them, where $A_{0,1,2}$ are the ${\chi }_{c2}$ helicity amplitudes. The measurement agrees with a pure $E1$ transition, and $M2$ and $E3$ contributions do not differ significantly from zero.

It is well known that fits to high energy data cannot sharply discriminate between asymptotic $\ln s$ and ${ln}^{2}s$ behavior of total cross section. We show that this is no longer the case when we impose the condition that the amplitudes also describe, on average, low energy data dominated by resonances. We demonstrate this by fitting real analytic amplitudes to high energy measurements of the $\gamma p$ total cross section, for $\sqrt{s}\ge 4\mathrm{G}\mathrm{e}\mathrm{V}$. We subsequently require that the asymptotic fit smoothly join the $\sqrt{s}=2.01\mathrm{G}\mathrm{e}\mathrm{V}$ cross section described by Damashek and Gilman [M. Damashek and F. J. Gilman, Phys. Rev. D 1, 1319 (1970).] as a sum of Breit-Wigner resonances. The results strongly favor the high energy ${ln}^{2}s$ fit of the form ${\sigma }_{\gamma p}=c_0+c_1\ln (\nu /m)+c_2{ln}^2(\nu /m)+{\beta }_{{\mathcal{P}}^{\prime }}/\sqrt{\nu /m}$, basically excluding a $\ln s$ fit of the form ${\sigma }_{\gamma p}=c_0+c_1\ln (\nu /m)+{\beta }_{{\mathcal{P}}^{\prime }}/\sqrt{\nu /m}$, where $\nu$ is the laboratory photon energy. This evidence for saturation of the Froissart [M. Froissart, Phys. Rev. 123, 1053 (1961).] bound for $\gamma p$ interactions is confirmed by applying the same analysis to $\pi p$ data using vector meson dominance.

Branching fraction measurements using $B$-meson decays to $K_S^0{\pi }^{+}{\pi }^{-}$ are presented. These measurements were obtained by analyzing a data sample of $88.9\times {10}^6$ ${\rm Y}(4S)\to B\overline{B}$ decays collected with the BABAR detector at the SLAC PEP-II asymmetric-energy $B$ factory. Using a maximum likelihood fit, the following branching fraction results were obtained: $\mathcal{B}(B^0\to K^0{\pi }^{+}{\pi }^{-})=(43.7\pm 3.8\pm 3.4)\times {10}^{-6}$, $\mathcal{B}(B^0\to K^{*+}{\pi }^{-})=(12.9\pm 2.4\pm 1.4)\times {10}^{-6}$, and $\mathcal{B}\mathbf{(}{B}^0\to D^{-}(\to K_S^0{\pi }^{-}){\pi }^{+}\mathbf{)}=(42.7\pm 2.1\pm 2.2)\times {10}^{-6}$. The $CP$ violating charge asymmetry ${\mathcal{A}}_{K^{*}\pi }$ for the decay $B^0\to K^{*+}{\pi }^{-}$ was measured to be ${\mathcal{A}}_{K^{*}\pi }=0.23\pm {0.18}_{-0.06}^{+0.09}$. For all these measurements the first error is statistical and the second is systematic.

It is known that in the Minkowski vacuum a bunch of IIA superstrings with D0-branes can be blown-up to a supersymmetric tubular D2-brane, which is supported against collapse by the angular momentum generated by crossed electric and magnetic Born-Infeld fields. In this paper we show how the multiple, smaller tubes with relative angular momentum could condense to a single, larger tube to stabilize the system. Such a phenomena could also be shown in the systems under the Melvin magnetic-tube or uniform magnetic field background. However, depending on the magnitude of field strength, a tube in the uniform magnetic field background may split into multiple, smaller tubes with relative angular momentum to stabilize the system.

We show that the addition of the Gauss-Bonnet term to Einstein gravity induces a tachyon mode in the spin two fluctuations of the Randall-Sundrum I model. We demonstrate that this instability is generically related to the presence of a flat negative tension brane, of codimension one, embedded in an anti-de Sitter background. In particular its presence is independent of $Z_2$-symmetry or compactness of the extra dimension. The gravitational tachyon mode persists for arbitrarily small but nonvanishing Gauss-Bonnet coupling. It is a bound state localized on the negative tension brane, much like the graviton zero-mode is localized on a positive tension one. We discuss the possible resolution of this instability by the inclusion of induced gravity terms on the branes or by an effective four-dimensional cosmological constant.

Relaxation process of a coherent scalar field oscillation in the thermal bath is investigated using nonequilibrium quantum field theory. The Langevin-type equation of motion is obtained which has a memory term and both additive and multiplicative noise terms. The dissipation rate of the oscillating scalar field is calculated for various interactions such as Yukawa coupling, three-body scalar interaction, and biquadratic interaction. When the background temperature is larger than the oscillation frequency, the dissipation rate arising from the interactions with fermions is suppressed due to the Pauli-blocking, while it is enhanced for interactions with bosons due to the induced effect. In both cases, we find that the microphysical detailed-balance relation drives the oscillating field to a thermal equilibrium state. That is, for low-momentum modes, the classical fluctuation-dissipation theorem holds and they relax to a state the equipartition law is satisfied, while higher-momentum modes reach the state the number density of each quanta consists of the thermal boson distribution function and zero-point vacuum contribution. The temperature-dependent dissipation rates obtained here are applied to the late reheating phase of inflationary universe. It is found that in some cases the reheat temperature may take a somewhat different value from the conventional estimates, and in an extreme case the inflaton can dissipate its energy without linear interactions that leads to its decay. Furthermore the evaporation rate of the Affleck-Dine field at the onset of its oscillation is calculated.

A pseudo-Nambu-Goldstone boson as curvaton avoids the $\eta$ problem of inflation which plagues most curvaton candidates. We point out that a concrete realization of the curvaton mechanism with a pseudo-Nambu-Goldstone boson can be found in the supersymmetric Peccei-Quinn mechanism resolving the strong CP problem. In the flaton models of Peccei-Quinn symmetry breaking, the angular degree of freedom associated with the QCD axion can naturally be a flat direction during inflation and provides successful curvature perturbations. In this scheme, the preferred values of the axion scale and the Hubble parameter during inflation turn out to be about ${10}^{10}$ and ${10}^{12}\mathrm{G}\mathrm{e}\mathrm{V}$, respectively. Moreover, it is found that a significant isocurvature component, (anti)correlated to the overall curvature perturbation, can be generated, which is a smoking gun for the curvaton scenario. Finally, non-Gaussianity in the perturbation spectrum at a potentially observable level is also possible.

The laser phase noise is one of the dominant noises for the gravitational wave detector LISA. Since it is impossible to maintain equal distances between the spacecraft, the time-delay interferometry (TDI) techniques are used to eliminate the laser phase noise along with the optical bench noise. It has been shown for stationary case that the TDI can be formulated in a systematic manner using algebraic geometrical methods, which generate all the data combinations canceling laser phase noise. These data combinations form a module over the polynomials, formally known as first module of syzygies, in three time-delay operators corresponding to the arms of LISA. The rotation induces a difference in up and down light travel times between the spacecraft, which results in a residual laser noise. Recently, several TDI data combinations have been given to cancel the laser phase noise by taking these differences into account. In this paper, we present a rigorous formalism similar to that of stationary case, by taking different arm lengths for up and down beams, resulting in a module over polynomials in six variables. We compute the transfer functions for the six beams and obtain the response to the gravitational wave signal for the generating set of above module.

The observation of ${\pi }_1(1600)\to \pi \rho$ is shown in the flux-tube model to be compatible with this state being a hybrid meson with branching ratio to this channel $\sim 30\%$. The $\pi \rho$ widths of other hybrids are related by rather general arguments. These results enable cross sections for photoproduction of hybrids to be predicted.

We investigate the color-singlet order parameters and the quark description of the Nambu-Goldstone (NG) bosons in the color-flavor locked (CFL) phase. We put emphasis on the NG boson (phason) called $H$ associated with the ${\mathrm{U}}_{\mathrm{B}}(1)$ symmetry breaking. We qualitatively argue the nature of $H$ as the second sound in the hydrodynamic regime. We articulate, based on a diquark picture, how the structural change of the condensates and the associated NG bosons occurs continuously from hadronic to CFL quark matter if the quark-hadron continuity is realized. We sharpen the qualitative difference between the flavor octet pions and the singlet phason. We propose a conjecture that superfluid $H$ matter undergoes a crossover to a superconductor with tightly bound diquarks, and then a crossover to superconducting matter with diquarks dissociated.

Based on an $87\mathrm{\text{−}}{\mathrm{f}\mathrm{b}}^{-1}$ data set collected by the BABAR detector at the PEP-II asymmetric-energy $B$ Factory, a search for $D^0\mathrm{\text{−}}{\overline{D}}^0$ mixing has been made using the semileptonic decay modes $D^{*+}\to {\pi }^{+}{D}^0$, $D^0\to K^{(*)}e\nu$ (+c.c.). The use of these modes allows unambiguous flavor tagging and a combined fit of the $D^0$ decay time and $D^{*+}\mathrm{\text{−}}{D}^0$ mass difference ($\Delta M$) distributions. The high-statistics sample of unmixed semileptonic $D^0$ decays is used to model the $\Delta M$ distribution and time dependence of mixed events directly from the data. Neural networks are used to select events and reconstruct the $D^0$. A result consistent with no charm mixing has been obtained, $R_{\mathrm{m}\mathrm{i}\mathrm{x}}=0.0023\pm 0.0012\pm 0.0004$. This corresponds to an upper limit of $R_{\mathrm{m}\mathrm{i}\mathrm{x}}<0.0042$ (90% C.L.).

We study noncommutative electrodynamics using the concept of covariant coordinates. We propose a scheme for interpreting the formalism and construct two basic examples, a constant field and a plane wave. Superposing these two, we find a modification of the dispersion relation. Our results differ from those obtained via the Seiberg-Witten map.

We investigate, from the point of view of an inertial frame, the response rate of a uniformly accelerated point source interacting with a massless real scalar field in Minkowski vacuum submitted to boundary conditions on a surface of general shape with walls parallel to the source moving direction. Following the procedure developed by Higuchi, Matsas, and Sudarsky, we show that the same response rate is obtained in the coaccelerated frame assuming the existence of the Fulling-Davies-Unruh thermal bath and imposing the same boundary conditions to the thermal field. We compute the explicit form of the response rate for the case of a rectangular waveguide where Dirichlet boundary conditions are imposed to the field, obtaining a considerable inhibition of this rate for realistic tube width and particle acceleration.

We explore a possible connection between two aspects of loop quantum gravity which have been extensively studied in the recent literature: the black-hole area-entropy law and the energy-momentum dispersion relation. We observe that the original Bekenstein argument for the area-entropy law implicitly requires information on the energy-momentum dispersion relation and on the position-momentum uncertainty relation. Recent results show that in first approximation black-hole entropy in loop quantum gravity depends linearly on the area, with small correction terms which have logarithmic or inverse-power dependence on the area. And it has been argued that in loop quantum gravity the dispersion relation should include terms that depend linearly on the Planck length, while no evidence of modification of the position-momentum uncertainty relation has been found. We observe that this scenario with Planck-length-linear modification of the dispersion relation and unmodified position-momentum uncertainty relation is incompatible with the black-hole-entropy results, since it would give rise to a term in the entropy formula going like the square root of the area.

In the Randall-Sundrum two D-brane system, we derive the gravitational theory on the branes. It is turned out from the consistency that one D-brane has the negative tension brane under Randall-Sundrum tuning and both gauge fields on the brane are related by scale transformation through the bulk R(Ramond)R/NS(Neveu-Schwarz)-NS fields. As with the single D-brane case, the gauge field which is supposed to be localized on the brane does not couple to the gravity on the branes.

We study the evolution of noninteracting and entangled cosmic string networks in the context of the velocity-dependent one-scale model. Such networks may be formed in several contexts, including brane inflation. We show that the frozen network solution $L\propto a$, although generic, is only a transient one, and that the asymptotic solution is still $L\propto t$ as in the case of ordinary (intercommuting) strings, although in the present context the universe will usually be string dominated. Thus the behavior of two strings when they cross does not seem to affect their scaling laws, but only their densities relative to the background.

We study the connection of the dynamics in relativistic field theories in a strong magnetic field with the dynamics of noncommutative field theories (NCFT). As an example, the Nambu-Jona-Lasinio models in spatial dimensions $d\ge 2$ are considered. We show that this connection is rather sophisticated. In fact, the corresponding NCFT are different from the conventional ones considered in the literature. In particular, the UV/IR mixing is absent in these theories. The reason for that is an inner structure (i.e., dynamical form factors) of neutral composites which plays an important role in providing consistency of the NCFT. An especially interesting case is that of a magnetic field configuration with the maximal number of independent nonzero tensor components. In that case, we show that the NCFT are finite for even $d$ and their dynamics is quasi-($1+1$)-dimensional for odd $d$. For even $d$, the NCFT describe a confinement dynamics of charged particles. The difference between the dynamics in strong magnetic backgrounds in field theories and that in string theories is briefly discussed.