We discuss and compare the charge-parity ($CP$) asymmetry in the charged Higgs boson decays $H^{-}\to {\overline{u}}_i{d}_j$ for the second and third generation quarks in the minimal supersymmetric standard model. As part of the analysis, we derive some general analytical formulas for the imaginary parts of two-point and three-point scalar one-loop integrals and use them for calculating vectorial- and tensorial-type integrals needed for the problem under consideration. We find that, even though each decay mode has a potential to yield a $CP$ asymmetry larger than 10%, further analysis based on the number of required charged Higgs events at colliders favors the $\overline{t}b$, $\overline{c}b$, and $\overline{c}s$ channels, whose asymmetry could reach 10%–15% in certain parts of the parameter space.

The generic predictions of two-texture zero neutrino mass matrices in the flavor basis have been examined especially in relation to the degeneracies between mass matrices within a class and interesting constraints on the neutrino parameters have been obtained. It is shown that the knowledge of the octant of ${\theta }_{23}$, the sign of $\cos \delta$, and neutrino mass hierarchy can be used to lift these degeneracies.

We study the discovery reach for nonstandard interactions (NSIs) in a neutrino factory experiment. After giving a theoretical, but model-independent, overview of the most relevant classes of NSIs, we present detailed numerical results for some of them. Our simulations take into account matter effects, uncertainties in the neutrino oscillation parameters, systematical errors, parameter correlations, and degeneracies. We perform scans of the parameter space, and show that a neutrino factory has excellent prospects of detecting NSIs originating from new physics at around 1 TeV, which is a scale favored by many extensions of the standard model. It will also turn out that the discovery reach depends strongly on the standard and nonstandard $CP$ violating phases in the Lagrangian.

We consider a particular large-radius limit of the world sheet $S$ matrix for strings propagating on ${\mathrm{AdS}}_5\times S^5$. This limiting theory interpolates smoothly between the so-called plane-wave and giant-magnon regimes of the theory. The sigma model in this region simplifies; it stands as a toy model of the full theory, and may be easier to solve directly. The $S$ matrix of the limiting theory is nontrivial, and receives contributions to all orders in the ${\alpha }^{\prime }$ expansion. We analyze a guess for the full world sheet $S$ matrix that was formulated recently by Beisert, Hernandez, and Lopez, and Beisert, Eden, and Staudacher, and take the corresponding limit. After doing a Borel resummation we find that the proposed $S$ matrix reproduces the expected results in the giant-magnon region. In addition, we rely on general considerations to draw some basic conclusions about the analytic structure of the $S$ matrix.

The cosmological evolution of the string landscape is expected to consist of multiple stages of old inflation with a large cosmological constant, each of which ends by tunneling. Old inflation has a well-known graceful exit problem as the observable universe becomes empty, devoid of any entropy. Simultaneously, in the quest for reheating the right degrees of freedom, it is important that the final stage of inflation reheat the standard model sector. It is known that inflation can occur naturally along a flat direction of the minimal supersymmetric standard model (MSSM), solving the reheating problem, but the initial conditions require a large degree of fine-tuning. In this paper, we study how inflation of a MSSM flat direction can be embedded into the string theory landscape to solve both the graceful exit problem of old inflation and the fine-tuning problem of MSSM inflation, elaborating on ideas of Bousso and Polchinski. The fluctuations of the MSSM flat direction during old inflation create regions with initial conditions favorable for eternal inflation, which also allows the cosmological constant to continue to relax. This final phase of inflation also provides all the usual benefits of MSSM inflation, including straightforward reheating into standard model degrees of freedom.

We consider salient cosmological features of a supersymmetric model which is left-right symmetric and therefore possessing gauged $B-L$ symmetry. The requirement of breaking parity and also obtaining charge preserving vacua introduces some unique features to this model (MSLRM), resulting in a preference for nonthermal leptogenesis. Assuming that the model preserves TeV scale supersymmetry, we show that the vacuum structure generically possesses domain walls, which can serve two important purposes. They can signal a secondary inflation required to remove unwanted relics such as gravitino and moduli and also generate lepton asymmetry by a mechanism similar to electroweak baryogenesis. The requirement of disappearance of domain walls imposes constraints on the soft parameters of the theory, testable at the TeV scale. We also propose an alternative model with spontaneous parity violation ($\mathrm{MSLR}\mathrm{P̸}$). Incorporating the same cosmological considerations in this case entails constraints on a different set of soft parameters.

We consider a population of small, high-velocity cosmic string loops. We assume the typical length of these loops is determined by the gravitational radiation scale and use the results of Polchinski and Rocha which pointed out their highly relativistic nature. A study of the gravitational wave emission from such a population is carried out. The large Lorentz boost involved causes the lowest harmonics of the loops to fall within the frequency band of the Laser Interferometer Gravitational Wave Observatory detector. Because of this feature the gravitational waves emitted by such loops can be detected in a periodic search rather than in burst or stochastic analysis. It is shown that, for interesting values of the string tension (${10}^{-10}\lesssim G\mu \lesssim {10}^{-8}$), the detector can observe loops at reasonably high redshifts and that detection is, in principle, possible. We compute the number of expected observations produced by such a process. For a 10 h search we find that this number is of order $O({10}^{-4})$. This is a consequence of the low effective number density of the loops traveling along the line of sight. However, small probabilities of reconnection and longer observation times can improve the result.

We discuss the moduli space approximation for heterotic M theory, both for the minimal case of two boundary branes only, and when a bulk brane is included. The resulting effective actions may be used to describe the cosmological dynamics in the regime where the branes are moving slowly, away from singularities. We make use of the recently derived colliding branes solution to determine the global structure of moduli space, finding a boundary at which the trajectories undergo a hard wall reflection. This has important consequences for the allowed moduli space trajectories, and for the behavior of cosmological perturbations in the model.

We study the effect of theoretical and parametric uncertainties on the ability of future Higgs coupling measurements at the International Linear Collider (ILC) to reveal deviations from the standard model (SM). To quantify the impact of these uncertainties we plot $\Delta {\chi }^2=25$ contours for the deviations between the SM Higgs couplings and the light Higgs couplings in the $m_h^{\max }$ benchmark scenario of the minimal supersymmetric standard model (MSSM). We consider the theoretical uncertainties in the SM Higgs decay partial widths and production cross section and the parametric uncertainties in the bottom and charm masses and the strong coupling ${\alpha }_s$. We find that the impact of the theoretical and parametric uncertainties is moderate in the first phase of ILC data-taking ($500{\mathrm{fb}}^{-1}$ at 350 GeV center-of-mass energy), reducing the reach in the $CP$-odd MSSM Higgs mass $M_A$ by about 10% to $\sim 500\mathrm{GeV}$, while in the second phase ($1000{\mathrm{fb}}^{-1}$ at 1000 GeV) these uncertainties are larger than the experimental uncertainties and reduce the reach in $M_A$ by about a factor of 2, from $\sim 1200$ down to $\sim 600\mathrm{GeV}$. The bulk of the effect comes from the parametric uncertainties in $m_b$ and ${\alpha }_s$, followed by the theoretical uncertainty in ${\Gamma }_b$.

Using heavy meson chiral perturbation theory, we consider the light quark mass and spatial volume dependence of the matrix elements of $\Delta B=2$ and $\Delta C=2$ four-quark operators relevant for $B_{(s)}^0-{\overline{B}}_{(s)}^0$ and $D^0-{\overline{D}}^0$ mixing, and the $B_s$ meson width difference. Our results for these matrix elements are obtained in the $N_f=2+1$ partially quenched theory, which becomes full QCD in the limit where sea and valence quark masses become equal. They can be used in extrapolation of lattice calculations of these matrix elements to the physical light quark masses and to infinite volume. An important conclusion of this paper is that the chiral extrapolations for matrix elements of heavy-light meson mixing beyond the standard model, and those relevant for the $B_s$ width difference are more complicated than that for the standard model mixing matrix elements.

Using $281{\mathrm{pb}}^{-1}$ of data recorded by the CLEO-c detector in $e^{+}{e}^{-}$ collisions at the $\psi (3770)$, corresponding to $0.78\times {10}^6$ $D^{+}{D}^{-}$ pairs, we investigate the substructure of the decay $D^{+}\to {\pi }^{-}{\pi }^{+}{\pi }^{+}$ using the Dalitz plot technique. We find that our data are consistent with the following intermediate states: $\rho (770){\pi }^{+}$, $f_2(1270){\pi }^{+}$, $f_0(1370){\pi }^{+}$, $f_0(1500){\pi }^{+}$, $f_0(980){\pi }^{+}$, and $\sigma {\pi }^{+}$. We confirm large $S$ wave contributions at low $\pi \pi$ mass. We set upper limits on contributions of other possible intermediate states. We consider three models of the $\pi \pi$ $S$ wave and find that all of them adequately describe our data.

We find a very large set of smooth horizonless geometries that have the same charges and angular momenta as the five-dimensional, maximally spinning, three-charge, supersymmetric black hole ($J^2=Q^3$). Our solutions are constructed using a four-dimensional Gibbons-Hawking base space that has a very large number of two-cycles. The entropy of our solutions is proportional to $\sqrt{Q}$. In the same class of solutions we also find microstates corresponding to zero-entropy black rings, and these are related to the microstates of the black hole by continuous deformations.

Using post-Newtonian equations of motion for fluid bodies valid to the second post-Newtonian order, we derive the equations of motion for binary systems with finite-sized, nonspinning but arbitrarily shaped bodies. In particular we study the contributions of the internal structure of the bodies (such as self-gravity) that would diverge if the size of the bodies were to shrink to zero. Using a set of virial relations accurate to the first post-Newtonian order that reflect the stationarity of each body, and redefining the masses to include 1PN and 2PN self-gravity terms, we demonstrate the complete cancellation of a class of potentially divergent, structure-dependent terms that scale as $s^{-1}$ and $s^{-5/2}$, where $s$ is the characteristic size of the bodies. This is further evidence of the strong equivalence principle, and supports the use of post-Newtonian approximations to derive equations of motion for strong-field bodies such as neutron stars and black holes. This extends earlier work done by Kopeikin.

We discuss the constraints coming from current observations of type Ia supernovae on cosmological models which allow sudden future singularities of pressure (with the scale factor and the energy density regular). We show that such a sudden singularity may happen in the very near future (e.g. within $10\times {10}^6\mathrm{\text{years}}$) and its prediction at the present moment of cosmic evolution cannot be distinguished, with current observational data, from the prediction given by the standard quintessence scenario of future evolution. Fortunately, sudden future singularities are characterized by a momentary peak of infinite tidal forces only; there is no geodesic incompleteness, which means that the evolution of the universe may eventually be continued throughout until another “more serious” singularity such as a big crunch or big rip.

Bayesian probability theory is used to analyze the oft-made assumption that humans are typical observers in the Universe. Some theoretical calculations make the selection fallacy that we are randomly chosen from a class of objects by some physical process, despite the absence of any evidence for such a process, or any observational evidence favoring our typicality. It is possible to favor theories in which we are typical by appropriately choosing their prior probabilities, but such assumptions should be made explicit to avoid confusion.

The construction of the first baryon operators for staggered lattice QCD exploited the taste symmetry to emulate physical quark flavor; contemporary $2+1$ flavor simulations explicitly include three physical quark flavors and necessitate interpreting a valence sector with 12 quarks. After discussing expected features of the resulting baryon spectrum, I consider the spectra of operators transforming irreducibly under $SU(3{)}_F\times \mathrm{GTS}$, the direct product of flavor $SU(3{)}_F$ and the geometrical time-slice group of the 1-flavor staggered theory. I then describe the construction of a set of maximally local baryon operators transforming irreducibly under $SU(3{)}_F\times \mathrm{GTS}$ and enumerate this set. In principle, the operators listed here could be used to extract the masses of all the lightest spin-$\frac{1}{2}$ and spin-$\frac{3}{2}$ baryon resonances of staggered QCD. Using appropriate operators from this set in partially quenched simulations should allow for particularly clean $2+1$ flavor calculations of the masses of the nucleon, $\Delta$, ${\Sigma }^{*}$, ${\Xi }^{*}$, and ${\Omega }^{-}$.

Here I explain why in chiral soliton models the hadronic transition operator of the pentaquark decay cannot be identified from the axial current.

We present a measurement of the top-quark mass in $p\overline{p}$ collisions at $\sqrt{s}=1.96\mathrm{TeV}$ which uses events with an inclusive signature of missing transverse energy and jets. The event selection is sensitive to $t\overline{t}\to W^{+}b{W}^{-}\overline{b}\to l\nu bq{q}^{\prime }\overline{b}$ independent of the lepton flavor and results in a large acceptance for $W\to \tau \nu$ decays. All-hadronic $t\overline{t}$ decays and events with identified electrons or muons are vetoed to provide a statistically independent sample with respect to all previous measurements. The top-quark mass is inferred from the distribution of the scalar sum of all jet transverse energies and the missing transverse energy. Using $311{\mathrm{pb}}^{-1}$ of integrated luminosity recorded by the Collider Detector at Fermilab, we measure a top-quark mass $m_t={172.3}_{-9.6}^{+10.8}(\mathrm{stat})\pm 10.8(\mathrm{syst})\mathrm{GeV}/c^2$. While the uncertainty on $m_t$ is larger than that of other measurements, the result is statistically uncorrelated with those of other methods and thus can help to reduce the overall $m_t$ uncertainty when combined with other existing measurements.

We investigate the large baryon number sector of the Einstein-Skyrme model as a possible model for baryon stars. Gravitating hedgehog skyrmions have been investigated previously and the existence of stable solitonic stars excluded due to energy considerations [P. Bizon and T. Chmaj, Phys. Lett. B 297, 55 (1992).]. However, in this paper we demonstrate that by generating gravitating Skyrmions using rational maps, we can achieve multibaryon bound states while recovering spherical symmetry in the limit where $B$ becomes large.

We use twist deformation techniques to analyze the behavior under area-preserving diffeomorphisms of quantum averages of Wilson loops in Yang-Mills theory on the noncommutative plane. We find that while the classical gauge theory is manifestly twist covariant, the holonomy operators break the quantum implementation of the twisted symmetry in the usual formal definition of the twisted quantum field theory. These results are deduced by analyzing general criteria which guarantee twist invariance of noncommutative quantum field theories. From this a number of general results are also obtained, such as the twisted symplectic invariance of noncommutative scalar quantum field theories with polynomial interactions and the existence of a large class of holonomy operators with both twisted gauge covariance and twisted symplectic invariance.