The sensitivity of next-generation gravitational-wave detectors such as Advanced LIGO and LCGT should be limited mostly by quantum noise with an expected technical progress to reduce seismic noise and thermal noise. Those detectors will employ the optical configuration of resonant-sideband-extraction that can be realized with a signal-recycling mirror added to the Fabry-Perot Michelson interferometer. While this configuration can reduce quantum noise of the detector, it can possibly increase laser frequency noise and intensity noise. The analysis of laser noise in the interferometer with the conventional configuration has been done in several papers, and we shall extend the analysis to the resonant-sideband-extraction configuration with the radiation-pressure effect included. We shall also refer to laser noise in the case we employ the so-called DC readout scheme.

We present a detailed study of the quark and lepton mass spectra in a $SO(10)$ framework with one ${10}_H$ and one ${\overline{126}}_H$ Higgs representations in the Yukawa sector. We consider in full generality the interplay between type I and type II seesaw for neutrino masses. We first perform a ${\chi }^2$ fit of fermion masses independent on the structure of the GUT Higgs potential and determine the regions of the parameter space that are preferred by the fermion mass sum rules. We then apply our study to the case of the minimal renormalizable SUSY $SO(10)$ GUT with one ${10}_H$, one ${\overline{126}}_H$, one ${126}_H$, and one ${210}_H$ Higgs representations. By requiring that proton decay bounds are fulfilled we identify a very limited area in the parameter space where all fermion data are consistently reproduced. We find that in all cases gauge coupling unification in the supersymmetric scenario turns out to be severely affected by the presence of lighter than GUT (albeit $B-L$ conserving) states. We then conclusively show that the minimal supersymmetric $SO(10)$ scenario here considered is not consistent with data. The fit of neutrino masses with type I and type II seesaws within a renormalizable $SO(10)$ framework strongly suggests a non-SUSY scenario for gauge unification.

We present a measurement of the unitarity triangle angle ${\varphi }_3$ using a Dalitz plot analysis of the $K_S^0{\pi }^{+}{\pi }^{-}$ decay of the neutral $D$ meson from the $B^{\pm }\to D^{(*)}{K}^{(*)\pm }$ process. The method exploits the interference between $D^0$ and ${\overline{D}}^0$ to extract the angle ${\varphi }_3$, strong phase $\delta$ and the ratio $r$ of suppressed and allowed amplitudes. We apply this method to a $357{\mathrm{fb}}^{-1}$ data sample collected by the Belle experiment. The analysis uses three modes: $B^{+}\to D{K}^{+}$, $B^{+}\to D^{*}{K}^{+}$ with $D^{*}\to D{\pi }^0$, and $B^{+}\to D{K}^{*+}$ with $K^{*+}\to K_S^0{\pi }^{+}$, as well as the corresponding charge-conjugate modes. From a combined maximum likelihood fit to the three modes, we obtain ${\varphi }_3=53°\genfrac{}{}{0ex}{}{+15°}{-18°}(\mathrm{stat})\pm 3°(\mathrm{syst})\pm 9°(\mathrm{\text{model}})$. The corresponding 2 standard deviation interval is $8°<{\varphi }_3<111°$.

The equivalence of quantum field theory and string theory as exemplified by the AdS/CFT correspondence is explored from the point of view of light cone quantization. On the string side we discuss the light cone version of the static string connecting a heavy external quark source to a heavy external antiquark source, together with small oscillations about the static string configuration. On the field theory side we analyze the weak/strong coupling transition in a ladder diagram model of the quark-antiquark system, also from the point of view of the light cone. Our results are completely consistent with those obtained by more standard covariant methods in the limit of infinitely massive quarks.

The semiclassical geometry of charged black holes is studied in the context of a two-dimensional dilaton gravity model where effects due to pair-creation of charged particles can be included in a systematic way. The classical mass-inflation instability of the Cauchy horizon is amplified and we find that gravitational collapse of charged matter results in a spacelike singularity that precludes any extension of the spacetime geometry. At the classical level, a static solution describing an eternal black hole has timelike singularities and multiple asymptotic regions. The corresponding semiclassical solution, on the other hand, has a spacelike singularity and a Penrose diagram like that of an electrically neutral black hole. Extremal black holes are destabilized by pair-creation of charged particles. There is a maximally charged solution for a given black hole mass but the corresponding geometry is not extremal. Our numerical data exhibits critical behavior at the threshold for black hole formation.

We revisit the problem of finding the entanglement entropy of a scalar field on a lattice by tracing over its degrees of freedom inside a sphere. It is known that this entropy satisfies the area law—entropy proportional to the area of the sphere—when the field is assumed to be in its ground state. We show that the area law continues to hold when the scalar field degrees of freedom are in generic coherent states and a class of squeezed states. However, when excited states are considered, the entropy scales as a lower power of the area. This suggests that, for large horizons, the ground state entropy dominates, whereas entropy due to excited states gives power-law corrections. We discuss possible implications of this result to black hole entropy.

We give detailed predictions for the diffractive associated production of SUSY Higgs bosons and top squarks at the LHC via exclusive double pomeron exchange mechanism. We study how the SUSY Higgs production cross section and the signal-over-background ratio are enhanced as a function of $\tan \beta$ in different regimes. The prospects are particularly promising in the antidecoupling regime, which we study in detail. We also give prospects for a precise measurement of the top squark mass using the threshold scan of central diffractive associated top squark events at the LHC.

We compare the grand-canonical partition function at fixed chemical potential $\mu$ with the canonical partition function at fixed baryon number $B$, formally and by numerical simulations at $\mu =0$ and $B=0$ with four flavors of staggered quarks. We verify that the free energy densities are equal in the thermodynamic limit, and show that they can be well described by the hadron resonance gas at $T<T_c$ and by the free fermion gas at $T>T_c$. Small differences between the two ensembles, for thermodynamic observables characterizing the deconfinement phase transition, vanish with increasing lattice size. These differences are solely caused by contributions of nonzero baryon density sectors, which are exponentially suppressed with increasing volume. The Polyakov loop shows a different behavior: for all temperatures and volumes, its expectation value is exactly zero in the canonical formulation, whereas it is always nonzero in the commonly used grand-canonical formulation. We clarify this paradoxical difference, and show that the nonvanishing Polyakov loop expectation value is due to contributions of nonzero triality states, which are not physical, because they give zero contribution to the partition function.

The chirally unbroken and the color-superconducting 2SC and CFL phases are investigated in the chiral limit within a Dyson-Schwinger approach for the quark propagator in QCD. The hierarchy of Green’s functions is truncated such that at vanishing density known results for the vacuum and at asymptotically high densities the corresponding weak-coupling expressions are recovered. The anomalous dimensions of the gap functions are analytically calculated. Based on the quark propagator the phase structure is studied, and results for the gap functions, occupation numbers, coherence lengths, and pressure differences are given and compared with the corresponding expressions in the weak-coupling regime. At moderate chemical potentials the quasiparticle pairing gaps are several times larger than the extrapolated weak-coupling results.

Using the QCD factorization approach, we reexamine the two-body hadronic charmless $B$-meson decays to final states involving a pseudoscalar ($P$) and a vector ($V$) meson, with inclusion of the penguin contractions of spectator-scattering amplitudes induced by the $b\to D{g}^{*}{g}^{*}$ (where $D=d$ or $s$, and $g^{*}$ denotes an off-shell gluon) transitions, which are of order ${\alpha }_s^2$. Their impacts on the $CP$-averaged branching ratios and $CP$-violating asymmetries are examined. We find that these higher order penguin contraction contributions have significant impacts on some specific decay modes. Since $B\to \pi K^{*}$, $K\rho$ decays involve the same electroweak physics as $B\to \pi K$ puzzles, we present a detailed analysis of these decays and find that the five $R$-ratios for the $B\to \pi K^{*}$, $K\rho$ system are in agreement with experimental data except for $R(\pi K^{*})$. Generally, these new contributions are found to be important for penguin-dominated $B\to PV$ decays.

We derive the full Wess-Zumino-Witten term of a gauged chiral Lagrangian in $D=4$ by starting from a pure Yang-Mills theory of gauged quark flavor in a flat, compactified $D=5$. The theory is compactified such that there exists a $B_5$ zero mode, and supplemented with quarks that are “chirally delocalized” with $q_L$ ($q_R$) on the left (right) boundary (brane). The theory then necessarily contains a Chern-Simons term (anomaly flux) to cancel the fermionic anomalies on the boundaries. The constituent quark mass represents chiral symmetry breaking and is a bilocal operator in $D=5$ of the form: ${\overline{q}}_{L}W{q}_R+\mathrm{h}.\mathrm{c}$, where $W$ is the Wilson line spanning the bulk, $0\le x^5\le R$, and is interpreted as a chiral meson field, $W=\exp (2i\tilde{\pi }/f_{\pi })$, where $f_{\pi }\sim 1/R$. The quarks are integrated out, yielding a Dirac determinant which takes the form of a “boundary term” (anomaly flux return), and is equivalent to Bardeen’s counterterm that connects consistent and covariant anomalies. The Wess-Zumino-Witten term then emerges straightforwardly, from the Yang-Mills Chern-Simons term, plus boundary term. The method is systematic and allows generalization of the Wess-Zumino-Witten term to theories of extra dimensions, and to express it in alternative and more compact forms. We give a novel form appropriate to the case of (unintegrated) massless fermions.

We perform a statistical analysis of models with $SU(5)$ and flipped $SU(5)$ gauge group in a type II orientifold setup. We investigate the distribution and correlation of properties of these models, including the number of generations and the hidden sector gauge group. Compared to the recent analysis [F. Gmeiner, R. Blumenhagen, G. Honecker, D. Lüst, and T. Weigand, F. GmeinerJ. High Energy Phys. 01 (2006) 004; , Fortschr. Phys. 54, 391 (2006).] of models with a standard model-like gauge group, we find very similar results.

We study the stability of the color-flavor-locked (CFL) phase of dense quark matter with regard to the formation of a nonzero Goldstone boson current. We show that an instability appears in the vicinity of the point ${\mu }_s=\Delta$ which marks the appearance of gapless fermion modes in the CFL phase. Here, ${\mu }_s=m_s^2/(2\mu )$ is the shift in chemical potential due to the strange quark mass and $\Delta$ is the gap in the chiral limit. We show that in the Goldstone boson current phase all components of the magnetic screening mass are real. In this work we do not take into account homogeneous kaon condensation. We study the effects of an instanton induced interaction of the magnitude required to suppress kaon condensation.

We study the electron-positron system in a strong, constant, and homogeneous magnetic field using the differential Bethe-Salpeter equation in the ladder approximation. We derive the fully relativistic two-dimensional form that the four-dimensional Bethe-Salpeter equation takes in the limit of an asymptotically strong magnetic field. A maximum value for the magnetic field is determined, which provides the full compensation of the positronium rest mass by the binding energy in the maximum symmetry state and the vanishing of the energy gap separating the electron-positron system from the vacuum. The compensation becomes possible owing to the falling-to-the-center phenomenon that occurs in a strong magnetic field because of the dimensional reduction. The solution to the Bethe-Salpeter equation corresponding to the vanishing energy momentum of the electron-positron system is obtained.

The observed late-time acceleration of the Universe may be the result of unknown physical processes involving either modifications of gravitation theory or the existence of new fields in high energy physics. In the former case, such modifications are usually related to the possible existence of extra dimensions (which is also required by unification theories), giving rise to the so-called brane cosmology. In this paper we investigate the viability of this idea by considering a particular class of brane scenarios in which a large-scale modification of gravity arises due to a gravitational leakage into extra dimensions. To this end, differently from other recent analyses, we combine orthogonal age and distance measurements at intermediary and high redshifts. We use observations of the lookback time to galaxy clusters, indirect estimates of the age of the Universe from the most recent large-scale structure and cosmic microwave background data, along with the recent detection of the baryon acoustic oscillations at $z=0.35$. In agreement with other recent analyses, we find that, although compatible with these age and distance measurements, a spatially closed scenario is largely favored by the current observational data. By restricting our analysis to a spatially flat universe, we show that the standard $\Lambda \mathrm{CDM}$ model is favored over the particular braneworld scenario here investigated.

We investigate the formation via tunneling of inflating (false-vacuum) bubbles in a true-vacuum background, and the reverse process. Using effective potentials from the junction condition formalism, all true- and false-vacuum bubble solutions with positive interior and exterior cosmological constant, and arbitrary mass are catalogued. We find that tunneling through the same effective potential appears to describe two distinct processes: one in which the initial and final states are separated by a wormhole (the Farhi-Guth-Guven mechanism), and one in which they are either in the same hubble volume or separated by a cosmological horizon. In the zero-mass limit, the first process corresponds to the creation of an inhomogenous universe from nothing, while the second mechanism is equivalent to the nucleation of true- or false-vacuum Coleman-De Luccia bubbles. We compute the probabilities of both mechanisms in the WKB approximation using semiclassical Hamiltonian methods, and find that—assuming both process are allowed—neither mechanism dominates in all regimes.

Interest in the elastic properties of regular lattices constructed from domain walls has recently been motivated by cosmological applications as solid dark energy. This work investigates the particularly simple examples of triangular, hexagonal, and square lattices in two dimensions and a variety of more complicated lattices in three dimensions which have cubic symmetry. The relevant rigidity coefficients are computed taking into account nonaffine perturbations where necessary, and these are used to evaluate the propagation velocity for any macroscopic scale perturbation mode. Using this information we assess the stability of the various configurations. It is found that triangular lattices are isotropic and stable, whereas hexagonal lattices are unstable. It is argued that the simple orthonormal cases of a square in two dimensions and the cube in three are stable, except to perturbations of infinite extent. We also find that the more complicated case of a rhombic dodecahedral lattice is stable, except to the existence of transverse modes in certain directions, whereas a lattice formed from truncated octahedra is unstable.

Gamma-ray bursts (GRBs) offer a potential way to extend the Hubble diagram to very high redshifts and to constrain the nature of dark energy in a way complementary to distant type Ia supernovae. However, gravitational lensing systematically brightens distant GRBs through the magnification bias, in addition to increasing the dispersions of distance measurements. We investigate how the magnification bias limits the cosmological usage of GRBs. We perform Monte-Carlo simulations of Swift GRBs assuming a cosmological constant dominated universe and then constrain the dark energy equation of state neglecting gravitational lens effects. The originally assumed model is recovered with 68% confidence limit even when the dispersion of inferred luminosities is comparable to that of type Ia supernovae. This implies that the bias is not so drastic for Swift GRBs as to change constraints on dark energy and its evolution. However, the precise degree of the bias in cosmological parameter determinations depends strongly on the shape of the luminosity function of GRBs. Therefore, an accurate determination of the shape of the luminosity function is required to remove the effect of gravitational lensing and to obtain an unbiased Hubble diagram.

Extensions of the minimal supersymmetric standard model (MSSM) with additional singlet scalar fields solve the important $\mu$-parameter fine-tuning problem of the MSSM. We compute and compare the neutral Higgs boson mass spectra, including one-loop corrections, of the following MSSM extensions: next-to-minimal supersymmetric standard model (NMSSM), the nearly-minimal supersymmetric standard model (nMSSM), and the $U(1{)}^{\prime }$-extended minimal supersymmetric standard model (UMSSM) by performing scans over model parameters. We find that the secluded $U(1{)}^{\prime }$-extended minimal supersymmetric standard model (sMSSM) is identical to the nMSSM if three of the additional scalars decouple. The dominant part of the one-loop corrections are model independent since the singlet field does not couple to MSSM particles other than the Higgs doublets. Thus, model-dependent parameters enter the masses only at tree level. We apply constraints from LEP bounds on the standard model and MSSM Higgs boson masses and the MSSM chargino mass, the invisible $Z$ decay width, and the $Z-Z^{\prime }$ mixing angle. Some extended models permit a Higgs boson with mass substantially below the SM LEP limit or above theoretical limits in the MSSM. Ways to differentiate the models via masses, couplings, decays and production of the Higgs bosons are discussed.

Recently a $J^{PC}=0^{++}$ [$X(1812)$] state with a mass near the threshold of $\omega$ and $\varphi$ has been observed by the BES collaboration in $J/\psi \to \gamma \omega \varphi$ decay. It has been suggested that it is a $I^G=0^{+}$ state. If it is true, this state fits in a mixing scheme based on quarkonia, glueball, and hybrid (QGH) very nicely where five physical states are predicted. Together with the known $f_0(1370)$, $f_0(1500)$, $f_0(1710)$, and $f_0(1790)$ states, $X(1812)$ completes the five members in this family. Using known experimental data on these particles, we determine the ranges of the mixing parameters and predict decay properties for $X(1812)$. We also discuss some features which may be able to distinguish between four-quark and hybrid mixing schemes.