We construct infinite new classes of supersymmetric solutions of $D=11$ supergravity that are warped products of ${\mathrm{AdS}}_3$ with an eight-dimensional manifold ${\mathcal{M}}_8$ and have nonvanishing four-form flux. In order to be compact, ${\mathcal{M}}_8$ is constructed as an $S^2$ bundle over a six-dimensional manifold $B_6$ which is either Kähler-Einstein or a product of Kähler-Einstein spaces. In the special cases that $B_6$ contains a two-torus, we also obtain new ${\mathrm{AdS}}_3$ solutions of type IIB supergravity, with constant dilaton and only five-form flux. Via the anti-de Sitter (AdS)-conformal field theory (CFT) correspondence the solutions with compact ${\mathcal{M}}_8$ will be dual to two-dimensional conformal field theories with $N=(0,2)$ supersymmetry. Our construction can also describe noncompact geometries and we discuss examples in type IIB which are dual to four-dimensional $N=1$ superconformal theories coupled to stringlike defects.

Breakdown of local physics in string theory at distances longer than the string scale is investigated. Such nonlocality would be expected to be visible in ultrahigh-energy scattering. The results of various approaches to such scattering are collected and examined. No evidence is found for nonlocality from strings whose length grows linearly with the energy. However, local quantum field theory does apparently fail at scales determined by gravitational physics, particularly strong gravitational dynamics. This amplifies locality bound arguments that such failure of locality is a fundamental aspect of physics. This kind of nonlocality could be a central element of a possible loophole in the argument for information loss in black holes.

The black hole information paradox apparently indicates the need for a fundamentally new ingredient in physics. The leading contender is nonlocality. Possible mechanisms for the nonlocality needed to restore unitarity to black hole evolution are investigated. Suggestions that such dynamics arise from ultra-Planckian modes in Hawking’s derivation are investigated and found not to be relevant, in a picture using smooth slices spanning the exterior and interior of the horizon. However, no simultaneous description of modes that have fallen into the black hole and outgoing Hawking modes can be given without appearance of a large kinematic invariant, or other dependence on ultra-Planckian physics. This indicates that a reliable argument for information loss has not been constructed, and that strong gravitational dynamics is important. Such dynamics has been argued to be fundamentally nonlocal in extreme situations, such as those required to investigate the fate of information.

In Coulomb gauge QCD in the Lagrangian formalism, energy divergences arise in individual diagrams. We give a proof on cancellation of these divergences to all orders of perturbation theory without obstructing the algebraic renormalizability of the theory.

Light-front Hamiltonian formulation of QCD with only one flavor of quarks is used in its simplest approximate version to calculate masses and boost-invariant wave functions of $c\overline{c}$ or $b\overline{b}$ mesons. The quark-antiquark Hamiltonian is obtained in the lowest (second) order of a weak-coupling expansion scheme for Hamiltonians of effective particles in quantum field theory. The derivation involves a heuristic ansatz for a gluon mass-gap that is meant to account for non-Abelian color dynamics of virtual effective particles in the Fock components with one or more effective gluons and can be improved order by order in the expansion. Fortunately, the resulting quark-antiquark Hamiltonian does not depend on any details of the ansatz within a large class of possibilities. It is shown that in the Hamiltonian approach in its simplest version the strong coupling constant $\alpha$ and quark mass $m$ (for suitable values of the renormalization group parameter $\lambda$ that is used in the calculation), can be adjusted so that (a) masses of 12 lightest well-established $b\overline{b}$ mesons are reproduced with accuracy better than 0.5% for all of them, which means 50 MeV in a few worst cases and on the order of 10 MeV in other cases, or (b) masses of 11 lightest $c\overline{c}$ mesons are reproduced with accuracy better than 3% for all of them, which means better than 100 MeV in a few worst cases and on the order of 10 MeV in the other cases, while the parameters $\alpha$ and $m$ are near the values expected in the cases (a) and (b) by analogy with other approaches. A fourth-order study in the same Hamiltonian scheme will be required to explicitly include renormalization group running of the parameters $\alpha$ and $m$ from the scale set by masses of bosons $W$ and $Z$ down to the values of $\lambda$ that are suitable in the bound-state calculations. In principle, one can use the Hamiltonian approach to describe the structure, decay, production, and scattering of heavy quarkonia in all kinds of motion, including velocities arbitrarily close to the speed of light. This work is devoted exclusively to a pilot study of masses of the quarkonia in the simplest version of the approach.

We discuss the implications of the recent measurement of the $B_s-{\overline{B}}_s$ oscillation frequency $\Delta M_s$ on the parameter space of $R$-parity violating supersymmetry. For completeness, we also discuss the bounds coming from leptonic, semileptonic, and nonleptonic $B$ decay modes, and point out some possibly interesting channels at the Large Hadron Collider.

We discuss the use of fermion polarization for studying neutral Higgs bosons at a photon collider. To this aim we construct polarization asymmetries which can isolate the contribution of a Higgs boson $\varphi$ in $\gamma \gamma \to f\overline{f}$, $f=\tau /t$, from that of the QED continuum. This can help in getting information on the $\gamma \gamma \varphi$ coupling in case $\varphi$ is a $CP$ eigenstate. We also construct $CP$-violating asymmetries which can probe $CP$ mixing in case $\varphi$ has indeterminate $CP$. Furthermore, we take the minimal supersymmetric standard model (MSSM) with $CP$ violation as an example to demonstrate the potential of these asymmetries in a numerical analysis. We find that these asymmetries are sensitive to the presence of a Higgs boson as well as its $CP$ properties over a wide range of MSSM parameters. In particular, the method suggested can cover the region where a light Higgs boson may have been missed by LEP due to $CP$ violation in the Higgs sector, and may be missed as well at the LHC.

We study the spectrum of low-lying eigenmodes of the kinetic operator for scalar particles, in the color adjoint representation of Yang-Mills theory. The kinetic operator is the covariant Laplacian, plus a constant which serves to renormalize mass. In the pure gauge theory, our data indicates that the interval between the lowest eigenvalue and the mobility edge tends to infinity in the continuum limit. On these grounds, it is suggested that the perturbative expression for the scalar propagator may be misleading even at distance scales that are small compared to the confinement scale. We also measure the density of low-lying eigenmodes, and find a possible connection to multicritical matrix models of order $m=1$.

We analyze and compare candidate crystal structures for the crystalline color superconducting phase that may arise in cold, dense but not asymptotically dense, three-flavor quark matter. We determine the gap parameter $\Delta$ and free energy $\Omega (\Delta )$ for many possible crystal structures within a Ginzburg-Landau approximation, evaluating $\Omega (\Delta )$ to order ${\Delta }^6$. In contrast to the two-flavor case, we find a positive ${\Delta }^6$ term and hence an $\Omega (\Delta )$ that is bounded from below for all the structures that we analyze. This means that we are able to evaluate $\Delta$ and $\Omega$ as a function of the splitting between Fermi surfaces for all the structures we consider. We find two structures with particularly robust values of $\Delta$ and the condensation energy, within a factor of 2 of those for the CFL phase which is known to characterize QCD at asymptotically large densities. The robustness of these phases results in their being favored over wide ranges of density. However, it also implies that the Ginzburg-Landau approximation is not quantitatively reliable. We develop qualitative insights into what makes a crystal structure favorable, and use these to winnow the possibilities. The two structures that we find to be most favorable are both built from condensates with face-centered cubic symmetry: in one case, the $⟨ud⟩$ and $⟨us⟩$ condensates are separately face-centered cubic; in the other case $⟨ud⟩$ and $⟨us⟩$ combined make up a face-centered cube.

The large-$x$ behavior of the transverse-momentum dependent quark distributions is analyzed in the factorization-inspired perturbative QCD framework, particularly for the naive time-reversal-odd quark Sivers function which is responsible for the single transverse-spin asymmetries in various semi-inclusive hard processes. By examining the dominant hard gluon exchange Feynman diagrams, and using the resulting power-counting rule, we find that the Sivers function has power behavior $(1-x{)}^4$ at $x\to 1$, which is one power of ($1-x$) suppressed relative to the unpolarized quark distribution. These power-counting results provide important guidelines for the parameterization of quark distributions and quark-gluon correlations.

We evaluate the cross section of the process $e^{+}{e}^{-}\to \gamma X(3872)$ in terms of the content of the $D^{*0}{\overline{D}}^0$ “molecular“ component in the wave function of the resonance $X(3872)$. If this component is dominating, the cross section of the reaction $e^{+}{e}^{-}\to \gamma X(3872)$ can reach up to about ${10}^{-3}$ of that for $e^{+}{e}^{-}\to D^{*}{\overline{D}}^{*}$ at energy slightly above the $D^{*}{\overline{D}}^{*}$ threshold, and the considered process can be a realistic source of the $X(3872)$ particles for the studies of this resonance.

$D^0\mathrm{\text{−}}{\overline{D}}^0$ mixing and significant $CP$ violation in the charm system may indicate the signature of new physics. In this study, we suggest that the coherent $D^0{\overline{D}}^0$ events from the decay of ${\rm Y}(1S)\to D^0{\overline{D}}^0$ can be used to measure both mixing parameters and $CP$ violation in charm decays. The neutral $D$ mesons from ${\rm Y}(1S)$ decay are strongly boosted, so that it will offer the possibility to measure the proper-time interval $\Delta t$ between the fully reconstructed $D^0$ and ${\overline{D}}^0$. Both coherent and time-dependent information can be used to extract $D^0\mathrm{\text{−}}{\overline{D}}^0$ mixing parameters. The sensitivity of the measurement should be improved at $B$ factories or at super-$B$.

We present improved measurements of the branching fractions of the color-suppressed decays ${\overline{B}}^0\to D^{(*)0}{h}^0$, where $h^0$ represents a light neutral meson ${\pi }^0$, $\eta$ or $\omega$. The measurements are based on a data sample of $140{\mathrm{fb}}^{-1}$ collected at the ${\rm Y}(4S)$ resonance with the Belle detector at the KEKB energy-asymmetric $e^{+}{e}^{-}$ collider, corresponding to 7 times the luminosity of the previous Belle measurements. All the measured branching fractions fall in the range $1.4–2.4\times {10}^{-4}$, which is significantly higher than theoretical predictions based on naive factorization.

We study the initial-state-radiation processes $e^{+}{e}^{-}\to K^{+}{K}^{-}{\pi }^{+}{\pi }^{-}\gamma$ and $e^{+}{e}^{-}\to K^{+}{K}^{-}{\pi }^0{\pi }^0\gamma$ using an integrated luminosity of $232{\mathrm{fb}}^{-1}$ collected at the ${\rm Y}(4S)$ mass with the BABAR detector at SLAC. Even though these reactions are dominated by intermediate states with excited kaons, we are able to study for the first time the cross section for $e^{+}{e}^{-}\to \varphi (1020)f_0(980)$ as a function of center-of-mass energy. We observe a structure near threshold consistent with a $1^{--}$ resonance with mass $m=2.175\pm 0.010\pm 0.015\mathrm{GeV}/c^2$ and width $\Gamma =58\pm 16\pm 20\mathrm{MeV}$. We observe no $Y(4260)$ signal and set a limit of ${\mathcal{B}}_{Y\to \varphi {\pi }^{+}{\pi }^{-}}·{\Gamma }_{ee}^Y<0.4\mathrm{eV}$ (90% confidence level), which excludes some models.

The main objective of this paper was to obtain the two-dimensional order and disorder thermal operators using the Thermofield Bosonization formalism. We show that the general property of the two-dimensional world according with the bosonized Fermi field at zero temperature can be constructed as a product of an order and a disorder variables which satisfy a dual field algebra holds at finite temperature. The general correlation functions of the order and disorder thermofields are obtained.

It was suggested that the massive Yang-Mills-Chern-Simons matrix model has three phases and that in one of them a non-Abelian gauge symmetry is dynamically generated. The analysis was at the one-loop level around a classical solution of fuzzy sphere type. We obtain evidences that three phases are indeed realized as nonperturbative vacua by using the improved perturbation theory. It also gives a good example that even if we start from a trivial vacuum, the improved perturbation theory around it enables us to observe nontrivial vacua.

The problem of the consistency of the finiteness of the supermoduli space integral in the limit of vanishing super-fixed point distance and the genus-dependence of the integral over the super-Schottky coordinates in the fundamental region containing a neighborhood of $|K_n|=0$ is resolved. Given a choice of the categories of isometric circles representing the integration region, the exponential form of bounds for superstring amplitudes is derived.

We present results of large-scale numerical simulations of the evolution of neutrino and antineutrino flavors in the region above the late-time post-supernova-explosion proto-neutron star. Our calculations are the first to allow explicit flavor evolution histories on different neutrino trajectories and to self-consistently couple flavor development on these trajectories through forward scattering-induced quantum coupling. Employing the atmospheric-scale neutrino mass-squared difference ($|\delta m^2|\simeq 3\times {10}^{-3}{\mathrm{eV}}^2$) and values of ${\theta }_{13}$ allowed by current bounds, we find transformation of neutrino and antineutrino flavors over broad ranges of energy and luminosity in roughly the “bi-polar” collective mode. We find that this large-scale flavor conversion, largely driven by the flavor off-diagonal neutrino-neutrino forward scattering potential, sets in much closer to the proto-neutron star than simple estimates based on flavor-diagonal potentials and Mikheyev-Smirnov-Wolfenstein evolution would indicate. In turn, this suggests that models of $r$-process nucleosynthesis sited in the neutrino-driven wind could be affected substantially by active-active neutrino flavor mixing, even with the small measured neutrino mass-squared differences.

We develop a numerical scheme to make a high-frequency skymap of gravitational-wave backgrounds (GWBs) observed via a space-based interferometer. Based on the cross correlation technique, the intensity distribution of anisotropic GWB can be directly reconstructed from the time-ordered data of cross correlation signals, with full knowledge of the detector’s antenna pattern functions. We demonstrate how the planned space interferometer, LISA, can make a skymap of GWB for a specific example of anisotropic signals. At the frequency higher than the characteristic frequency $f_{*}=1/(2\pi L)$, where $L$ is the arm-length of the detector, the reconstructed skymap free from the instrumental noise potentially reaches the angular resolution up to the multipoles $\ell \sim 10$. The presence of instrumental noises degrades the angular resolution. The resultant skymap has angular resolution with multipoles $\ell \le 6\sim 7$ for the anisotropic signals with signal-to-noise ratio $\mathrm{S}/\mathrm{N}>5$.