We discuss the physics of superbeam upgrades, where we focus on T2KK, a NuMI beam line based experiment NOνA*, and a wide-band beam (WBB) experiment independent of the NuMI beam line. For T2KK, we find that the Japan-Korea baseline helps resolve parameter degeneracies, but the improvement due to correlated systematics between the two detectors (using identical detectors) is only moderate. For an upgrade of NOνA with a liquid argon detector, we demonstrate that the Ash River site is preferred compared to alternatives, such as at the second oscillation maximum, and is the optimal site within the U.S. For a WBB experiment, we find that high proton energies and long decay tunnels are preferable. We compare water Cherenkov and liquid argon technologies, and find the break-even point in detector cost at about $4:1$. In order to compare the physics potential of the different experimental configurations, we use the concept of exposure to normalize the performance. We find that experiments with WBBs are the best experimental concept. NOνA* could be competitive with sufficient luminosity. If ${sin}^{2}2{\theta }_{13}>0.01$, a WBB experiment can perform better than a neutrino factory.

The 5.4 kton MINOS far detector has been taking charge-separated cosmic ray muon data since the beginning of August, 2003 at a depth of 2070 m.w.e. in the Soudan Underground Laboratory, Minnesota, USA. The data with both forward and reversed magnetic field running configurations were combined to minimize systematic errors in the determination of the underground muon charge ratio. When averaged, two independent analyses find the charge ratio underground to be $N_{{\mu }^{+}}/N_{{\mu }^{-}}=1.374\pm 0.004(\mathrm{stat}{)}_{-0.010}^{+0.012}(\mathrm{sys})$. Using the map of the Soudan rock overburden, the muon momenta as measured underground were projected to the corresponding values at the surface in the energy range 1–7 TeV. Within this range of energies at the surface, the MINOS data are consistent with the charge ratio being energy independent at the 2 standard deviation level. When the MINOS results are compared with measurements at lower energies, a clear rise in the charge ratio in the energy range 0.3–1.0 TeV is apparent. A qualitative model shows that the rise is consistent with an increasing contribution of kaon decays to the muon charge ratio.

In this paper we calculate the zero point energy density experienced by observers on ${\mathcal{M}}^4$ due to a massless scalar field defined throughout ${\mathcal{M}}^4\times {\mathbf{T}}_F^2$, where ${\mathbf{T}}_F^2$ are fuzzy extra dimensions. Using the Green’s function approach we calculate the energy density for the commutative torus and the fuzzy torus. We also calculate the energy density for the fuzzy torus using the Hamiltonian approach. Agreement is shown between the Green’s function and Hamiltonian approaches.

A general class of loop quantizations for anisotropic models is introduced and discussed, which enhances loop quantum cosmology by relevant features seen in inhomogeneous situations. The main new effect is an underlying lattice which is being refined during dynamical changes of the volume. In general, this leads to a new feature of dynamical difference equations which may not have constant step-size, posing new mathematical problems. It is discussed how such models can be evaluated and what lattice refinements imply for semiclassical behavior. Two detailed examples illustrate that stability conditions can put strong constraints on suitable refinement models, even in the absence of a fundamental Hamiltonian which defines changes of the underlying lattice. Thus, a large class of consistency tests of loop quantum gravity becomes available. In this context, it will also be seen that quantum corrections due to inverse powers of metric components in a constraint are much larger than they appeared recently in more special treatments of isotropic, free scalar models where they were artificially suppressed.

We present a complete set of the equations and matching conditions required for the description of physically meaningful charged, dissipative, spherically symmetric gravitational collapse with shear. Dissipation is described with both free-streaming and diffusion approximations. The effects of viscosity are also taken into account. The roles of different terms in the dynamical equation are analyzed in detail. The dynamical equation is coupled to a causal transport equation in the context of Israel-Stewart theory. The decrease of the inertial mass density of the fluid, by a factor which depends on its internal thermodynamic state, is reobtained, with the viscosity terms included. In accordance with the equivalence principle, the same decrease factor is obtained for the gravitational force term. The effect of the electric charge on the relation between the Weyl tensor and the inhomogeneity of the energy density is discussed.

Recent Wilkinson Microwave Anisotropy Probe (WMAP) data confirm the cosmic microwave background (CMB) quadrupole anomaly. We further elaborate our previous proposal that the quadrupole power can be naturally suppressed in axis-symmetric universes. In particular, we discuss in greater detail the CMB quadrupole anisotropy and considerably improve our analysis. As a result, we obtain tighter constraints on the direction of the axis of symmetry as well as on the eccentricity at decoupling. We find that the quadrupole amplitude can be brought in accordance with observations with an eccentricity at decoupling of about $0.64\times {10}^{-2}$. Moreover, our determination of the direction of the symmetry axis is in reasonable agreement with recent statistical analyses of cleaned CMB temperature fluctuation maps obtained by means of improved internal linear combination methods as galactic foreground subtraction technique.

In finite volume the partition function of QCD with a given $\theta$ is a sum of different topological sectors with a weight primarily determined by the topological susceptibility. If a physical observable is evaluated only in a fixed topological sector, the result deviates from the true expectation value by an amount proportional to the inverse space-time volume $1/V$. Using the saddle point expansion, we derive formulas to express the correction due to the fixed topological charge in terms of a $1/V$ expansion. Applying this formula, we propose a class of methods to determine the topological susceptibility in QCD from various correlation functions calculated in a fixed topological sector.

We compute the ground-state energies of a heavy-light $K\mathrm{\text{−}}\Lambda$ like system as a function of the relative distance $r$ of the hadrons. The heavy quarks, one in each hadron, are treated as static. Then, the energies give rise to an adiabatic potential $V_a(r)$ which we use to study the structure of the five-quark system. The simulation is based on an anisotropic and asymmetric lattice with Wilson fermions. Energies are extracted from spectral density functions obtained with the maximum entropy method. Our results are meant to give qualitative insight: Using the resulting adiabatic potential in a Schrödinger equation produces bound-state wave functions which indicate that the ground state of the five-quark system resembles a hadronic molecule, whereas the first excited state, having a very small root-mean-square (rms) radius, is probably better described as a five-quark cluster, or a pentaquark. We hypothesize that an all light-quark pentaquark may not exist, but in the heavy-quark sector it might, albeit only as an excited state.

Using an integration formula recently derived by Conrey, Farmer, and Zirnbauer, we calculate the expectation value of the phase factor of the fermion determinant for the staggered lattice QCD action in one dimension. We show that the chemical potential can be absorbed into the quark masses; the theory is in the same chiral symmetry class as QCD in three dimensions at zero chemical potential. In the limit of a large number of colors and fixed number of lattice points, chiral symmetry is broken spontaneously, and our results are in agreement with expressions based on a chiral Lagrangian. In this limit, the eigenvalues of the Dirac operator are correlated according to random matrix theory for QCD in three dimensions. The discontinuity of the chiral condensate is due to an alternative to the Banks-Casher formula recently discovered for QCD in four dimensions at nonzero chemical potential. The effect of temperature on the average phase factor is discussed in a schematic random matrix model.

A measurement of the ${\tau }^{-}\to K^{-}{\pi }^0{\nu }_{\tau }$ branching fraction has been made using $230.2{\mathrm{fb}}^{-1}$ of data recorded by the BABAR detector at the PEP-II $e^{+}{e}^{-}$ collider, located at the Stanford Linear Accelerator Center (SLAC), at a center-of-mass energy $\sqrt{s}$ close to 10.58 GeV. We measure $\mathcal{B}({\tau }^{-}\to K^{-}{\pi }^0{\nu }_{\tau })=(0.416\pm 0.003(\mathrm{stat})\pm 0.018(\mathrm{syst}))\%$.

We calculate the complete one-loop off-shell three-point scalar-photon vertex in arbitrary gauge and dimension for scalar quantum electrodynamics. Explicit results are presented for the particular cases of dimensions 3 and 4 both for massive and massless scalars. We then propose nonperturbative forms of this vertex that coincide with the perturbative answer to order $e^2$.

The curvaton scenario for the generation of the cosmological curvature perturbation on large scales represents an alternative to the standard slow-roll scenario of inflation in which the observed density perturbations are due to fluctuations of the inflaton field itself. Its basic assumption is that the initial curvature perturbation due to the inflaton field is negligible. This is attained by lowering the energy scale of inflation, thereby highly suppressing the amount of gravitational waves produced during inflation. We compute the power spectrum of the gravitational waves generated at second order in perturbation theory by the curvaton (isocurvature) perturbations between the end of inflation and the curvaton decay. An interesting property of this contribution to the tensor perturbations is that it is directly proportional to the amount of non-Gaussianity predicted within the curvaton scenario. We show that the spectrum of gravitational waves may be in the range of future gravitational wave detectors.

If dark matter decays to electromagnetically interacting particles, it can inject energy into the baryonic gas and thus affect the processes of recombination and reionization. This leaves an imprint on the cosmic microwave background (CMB): the large-scale polarization is enhanced, and the small-scale temperature fluctuation is damped. We use the Wilkinson Microwave Anisotropy Probe (WMAP) three-year data combined with galaxy surveys to constrain radiatively decaying dark matter. Our new limits to the dark-matter decay width are about 10 times stronger than previous limits. For dark-matter lifetimes that exceed the age of the Universe, a limit of $\zeta {\Gamma }_{\chi }<1.7\times {10}^{-25}{\mathrm{s}}^{-1}$ (95% C.L.) is derived, where $\zeta$ is the efficiency of converting decay energy into ionization energy. Limits for lifetimes short compared with the age of the Universe are also derived. We forecast improvements expected from the Planck satellite.

We demonstrate the possibility of studying weakly interacting new particles in weak-boson fusion, using the example of supersymmetric same-sign charginos. This signal could establish the existence of Majorana neutralinos and give access to their electroweak couplings. It can be observed over (supersymmetric) QCD backgrounds provided the charginos are light and not too close to the squark mass. We finally show how same-sign fermion production can be distinguished from same-sign scalars or vectors arising in other models of new physics.

In a pilot study, we use the topological charge density defined by the eigenmodes of the overlap Dirac operator (with ultraviolet filtering by mode truncation) to search for lumps of topological charge in $SU(2)$ pure gauge theory. Augmenting this search with periodic and antiperiodic temporal boundary conditions for the overlap fermions, we demonstrate that the lumps can be classified either as calorons or as separate caloron constituents (dyons). Inside the topological charge clusters, the (smeared) Polyakov loop is found to show the typical profile characteristic for calorons and dyons. This investigation, motivated by recent caloron/dyon model studies, is performed at the deconfinement phase transition for $SU(2)$ gluodynamics on ${20}^3\times 6$ lattices described by the tadpole-improved Lüscher-Weisz (LW) action. The transition point has been carefully located. As a necessary condition for the caloron/dyon detection capability, we check that the LW action, in contrast to the Wilson action, generates lattice ensembles, for which the overlap Dirac eigenvalue spectrum smoothly behaves under smearing and under the change of the boundary conditions.

We present a search for the decay $B^{+}\to {\tau }^{+}\nu$ using $383\times {10}^{6}B\overline{B}$ pairs collected at the ${\rm Y}(4S)$ resonance with the BABAR detector at the SLAC PEP-II $B$-Factory. A sample of events with one reconstructed semileptonic $B$ decay ($B^{-}\to D^0\ell -{\overline{\nu }}_{\ell }X$) is selected, and in the recoil a search for $B^{+}\to {\tau }^{+}\nu$ is performed. The $\tau$ is identified in the following channels: ${\tau }^{+}\to e^{+}\nu \overline{\nu }$, ${\tau }^{+}\to {\mu }^{+}\nu \overline{\nu }$, ${\tau }^{+}\to {\pi }^{+}\overline{\nu }$, and ${\tau }^{+}\to {\pi }^{+}{\pi }^0\overline{\nu }$. We measure a branching fraction of $\mathcal{B}(B^{+}\to {\tau }^{+}\nu )=(0.9\pm 0.6(\mathrm{stat}.)\pm 0.1(\mathrm{syst}.))\times {10}^{-4}$. In the absence of a significant signal, we calculate an upper limit at the 90% confidence level of $\mathcal{B}(B^{+}\to {\tau }^{+}\nu )<1.7\times {10}^{-4}$. We calculate the product of the $B$ meson decay constant $f_B$ and $|V_{\mathrm{ub}}|$ to be $f_B·|V_{\mathrm{ub}}|=({7.2}_{-2.8}^{+2.0}(\mathrm{stat}.)\pm 0.2(\mathrm{syst}.))\times {10}^{-4}\mathrm{GeV}$.

With the many ambitious proposals afoot for new generations of very large telescopes, along with spectrographs of unprecedented resolution, there arises the real possibility that the time evolution of the cosmological redshift may, in the not too distant future, prove to be a useful tool rather than merely a theoretical curiosity. Here I contrast this approach with the standard cosmological procedure based on the luminosity (or any other well-defined) distance. I then show that such observations would not only provide a direct measure of all the associated cosmological parameters of the LCDM model, but would also provide wide-ranging internal consistency checks. Further, in a more general context, I show that without introducing further time derivatives of the redshift one could in fact map out the dark energy equation of state should the LCDM model fail. A consideration of brane-world scenarios and interacting dark energy models serves to emphasize the fact that the usefulness of such observations would not be restricted to high redshifts.

We consider big bang nucleosynthesis (BBN) with long-lived charged massive particles. Before decaying, the long-lived charged particle recombines with a light element to form a bound state like a hydrogen atom. This effect modifies the nuclear-reaction rates during the BBN epoch through the modifications of the Coulomb field and the kinematics of the captured light elements, which can change the light element abundances. It is possible for heavier nuclei abundances such as ${}^7\mathrm{Li}$ and ${}^7\mathrm{Be}$ to decrease sizably, while the ratios $Y_p$, D/H, and ${}^3\mathrm{He}/\mathrm{H}$ remain unchanged. This may solve the current discrepancy between the BBN prediction and the observed abundance of ${}^7\mathrm{Li}$. If future collider experiments find signals of a long-lived charged particle inside the detector, the information of its lifetime and decay properties could provide insights into not only the particle physics models but also the phenomena in the early Universe, in turn.

We search data from the Energetic Gamma Ray Experiment Telescope (EGRET) for a gamma-ray line in the energy range 0.1–10 GeV from the $10°\times 10°$ region around the Galactic center. Our null results lead to upper limits to the line flux from the Galactic center. Such lines may have appeared if the dark matter in the Galactic halo is composed of weakly interacting massive particles (WIMPs) in the mass range 0.1–10 GeV. For a given dark-matter-halo model, our null search translates to upper limits to the WIMP two-photon annihilation cross section as a function of WIMP mass. We show that, for a toy model in which Majorana WIMPs in this mass range annihilate only to electron-positron pairs, these upper limits supersede those derived from measurements of the 511-keV line and continuum photons from internal bremsstrahlung at the Galactic center.