We compare the color-evaporation model (CEM) and nonrelativistic QCD (NRQCD) factorization predictions for inclusive quarkonium production. Using the NRQCD factorization formulas for quarkonium production and for perturbative $Q\overline{Q}$ production, we deduce relationships that are implied by the CEM between the nonperturbative NRQCD matrix elements that appear in the factorization formula for quarkonium production. These relationships are at odds with the phenomenological values of the matrix elements that have been extracted from the Tevatron data for charmonium production at large transverse momentum. A direct comparison of the CEM and NRQCD factorization predictions with the CDF charmonium production data reveals that the CEM fits to the data are generally unsatisfactory, while the NRQCD factorization fits are generally compatible with the data. The inclusion of $k_T$ smearing improves the CEM fits substantially, but significant incompatibilities remain. The NRQCD factorization fits to the ${\chi }_c$ data indicate that multiple gluon radiation is an essential ingredient in obtaining the correct shape of the cross section as a function of $p_T$.

The bounds on the neutrino mixing angles and $CP$ Dirac phase for an $SO(10)$ model with lopsided mass matrices, arising from the presence of ${\mathbf{16}}_H$ and ${\overline{\mathbf{16}}}_H$ Higgs representations, are studied by variation of the one real and three unknown complex input parameters for the right-handed Majorana neutrino mass matrix. The scatter plots obtained favor nearly maximal atmospheric neutrino mixing, while the reactor neutrino mixing lies in the range ${10}^{-5}\lesssim {sin}^2{\theta }_{13}\lesssim 1\times {10}^{-2}$ with values greater than ${10}^{-3}$ most densely populated. A rather compelling scenario within the model follows, if we restrict the three unknown complex parameters to their imaginary axes and set two of them equal. We then find the scatter plots are reduced to narrow bands, as the mixing angles and $CP$ phase become highly correlated and predictive. The bounds on the mixing angles and phase then become $0.45\lesssim {sin}^2{\theta }_{23}\lesssim 0.55$, $0.38\lesssim {tan}^2{\theta }_{12}\lesssim 0.50$, $0.002\lesssim {sin}^2{\theta }_{13}\lesssim 0.003$, and $60°\lesssim \pm {\delta }_{CP}\lesssim 85°$. Moreover, successful leptogenesis and subsequent baryogenesis are also obtained, with ${\eta }_B$ increasing from $(2.7\mathrm{to}6.3)\times {10}^{-10}$ as ${sin}^2{\theta }_{23}$ increases from 0.45 to 0.55.

Using data samples collected at $\sqrt{s}=3.686\mathrm{GeV}$ and 3.650 GeV by the BESII detector at the BEPC, the branching fraction of $\psi (2S)\to 3({\pi }^{+}{\pi }^{-})$ is measured to be $[5.45\pm 0.42(\mathrm{stat})\pm 0.87(\mathrm{syst})]\times {10}^{-4}$, and the relative branching fraction of $J/\psi \to 2({\pi }^{+}{\pi }^{-})$ to that of $J/\psi \to {\mu }^{+}{\mu }^{-}$ is measured to be $[6.01\pm 0.20(\mathrm{stat})\pm 0.48(\mathrm{syst})]\%$ via $\psi (2S)\to {\pi }^{+}{\pi }^{-}J/\psi ,J/\psi \to 2({\pi }^{+}{\pi }^{-})$. The electromagnetic form factor of $3({\pi }^{+}{\pi }^{-})$ is determined to be $0.19\pm 0.02$ and $0.24\pm 0.02$ at $\sqrt{s}=3.650\mathrm{GeV}$ and 3.686 GeV, respectively.

The late-time evolution of the charged massive Dirac fields in the background of a Reissner-Norström (RN) black hole is studied. It is found that the intermediate late-time behavior is dominated by an inverse power-law decaying tail without any oscillation in which the dumping exponent depends not only on the multiple number of the wave mode but also on the field parameters. It is also found that, at very late times, the oscillatory tail has the decay rate of $t^{-5/6}$ and the oscillation of the tail has the period $2\pi /\mu$ which is modulated by two types of long-term phase shifts.

We demonstrate that a gas of wrapped branes in the early Universe can help resolve the cosmological Dine-Seiberg/Brustein-Steinhardt overshoot problem in the context of moduli stabilization with steep potentials in string theory. Starting from this mechanism, we propose a cosmological model with a natural setting in the context of an early phase dominated by brane and string gases. The Universe inflates at early times due to the presence of a wrapped two brane (domain wall) gas and all moduli are stabilized. A natural graceful exit from the inflationary regime is achieved. However, the basic model suffers from a generalized domain wall/reheating problem and cannot generate a scale invariant spectrum of fluctuations without additional physics. Several suggestions are presented to address these issues.

We introduce continuous Wilson lines to reduce the rank of the gauge group in orbifold constructions. In situations where the orbifold twist can be realized as a rotation in the root lattice of a grand unified group we derive an appealing geometric picture of the symmetry breakdown. This symmetry breakdown is smooth and corresponds to a standard field theory Higgs mechanism. The embedding into heterotic string theory is discussed.

Calorons of the $SU(N)$ gauge group with nontrivial holonomy, i.e. periodic instantons with arbitrary eigenvalues of the Polyakov line at spatial infinity, can be viewed as composed of $N$ Bogomolnyi-Prasad-Sommerfeld monopoles or dyons. Using the metric of the caloron moduli space found previously we compute the integration measure over caloron collective coordinates in terms of the constituent monopole positions and their $U(1)$ phases. In the limit of small separations between dyons and/or trivial holonomy, calorons reduce locally to the standard instantons whose traditional collective coordinates are the instanton center, size, and orientation in the color space. We show that in this limit the instanton collective coordinates can be explicitly written through dyons’ positions and phases, and that the $N$-dyon measure coincides exactly with the standard instanton one.

We study $1/2$ Bogomol’nyi-Prasad-Sommerfield (BPS) domain walls, $1/2$ BPS flux tubes (strings), and their $1/4$ BPS junctions. We consider the simplest example of $\mathcal{N}=2$ Abelian gauge theory with two charged matter hypermultiplets which contains all of the above-listed extended objects. In particular, we focus on string-wall junctions (boojums) and calculate their energy. It turns out to be logarithmically divergent in the infrared domain. We compute this energy first in the ($2+1$)-dimensional effective theory on the domain wall and then, as a check, obtain the same result from the point of view of ($3+1$)-dimensional bulk theory. Next, we study interactions of boojums considering all possible geometries of string-wall junctions and directions of the string magnetic fluxes.

Cosmogenic neutrinos reach the Earth with energies around ${10}^9\mathrm{GeV}$, and their interactions with matter will be measured in upcoming experiments (Auger, IceCube). Models with extra dimensions and the fundamental scale at the TeV could imply signals in these experiments. In particular, the production of microscopic black holes by cosmogenic neutrinos has been extensively studied in the literature. Here we make a complete analysis of gravity-mediated interactions at larger distances, where they can be calculated in the eikonal approximation. In these processes a neutrino of energy $E_{\nu }$ interacts elastically with a parton inside a nucleon, loses a small fraction $y$ of its energy, and starts a hadronic shower of energy $y{E}_{\nu }\ll E_{\nu }$. We analyze the ultraviolet dependence and the relevance of graviton emission in these processes, and show that they are negligible. We also study the energy distribution of cosmogenic events in AMANDA and IceCube and the possibility of multiple-bang events. For any neutrino flux, the observation of an enhanced rate of neutral current events above 100 TeV in neutrino telescopes could be explained by TeV-gravity interactions. The values of the fundamental scale of gravity that IceCube could reach are comparable to those to be explored at the LHC.

We take further steps in the development of the characteristic approach to enable handling the physical problem of a compact self-gravitating object, such as a neutron star, in close orbit around a black hole. We examine different options for setting the initial data for this problem and, in order to shed light on their physical relevance, we carry out short time evolution of this data. To this end we express the matter part of the characteristic gravity code so that the hydrodynamics are in conservation form. The resulting gravity plus matter relativity code provides a starting point for more refined future efforts at longer term evolution. In the present work we find that, independently of the details of the initial gravitational data, the system quickly flushes out spurious gravitational radiation and relaxes to a quasiequilibrium state with an approximate helical symmetry corresponding to the circular orbit of the star.

We show that the leading-power $B$ meson wave function can be extracted reliably from the photon energy spectrum of the $B\to \gamma l\nu$ decay up to $O(1/m_b^2)$ and $O({\alpha }_s^2)$ uncertainty, $m_b$ being the $b$ quark mass and ${\alpha }_s$ the strong coupling constant. The $O(1/m_b)$ corrections from heavy-quark expansion can be absorbed into a redefined leading-power $B$ meson wave function. The two-parton $O(1/m_b)$ corrections cancel exactly, and the three-parton $B$ meson wave functions turn out to contribute at $O(1/m_b^2)$. The constructive long-distance contribution through the $B\to V\to \gamma$ transition, $V$ being a vector meson, almost cancels the destructive $O({\alpha }_s)$ radiative correction. Using models of the leading-power $B$ meson wave function available in the literature, we obtain the photon energy spectrum in the perturbative QCD framework, which is then compared with those from other approaches.

We make a theoretical study of the $s$-wave interaction of the nonet of vector mesons with the octet of pseudoscalar mesons starting from a chiral invariant Lagrangian and implementing unitarity in coupled channels. By looking for poles in the unphysical Riemann sheets of the unitarized scattering amplitudes, we get two octets and one singlet of axial-vector dynamically generated resonances. The poles found can be associated with most of the low lying axial-vector resonances quoted by the Particle Data Group: $b_1(1235)$, $h_1(1170)$, $h_1(1380)$, $a_1(1260)$, $f_1(1285)$, and two poles to the $K_1(1270)$ resonance. We evaluate the couplings of the resonances to the $VP$ states and the partial decay widths in order to reinforce the arguments in the discussion.

The resonant substructure in $D^0\to K_S^0{\pi }^{+}{\pi }^{-}$ decays is described by a combination of ten quasi two-body intermediate states which include both $CP$-even and $CP$-odd eigenstates and one doubly Cabibbo suppressed channel. We present a formalism that connects the variation in $D^0$ decay time over the Dalitz plot with the mixing parameters, $x$ and $y$, that describe off-shell and on-shell $D^0-{\overline{D}}^0$ mixing. We analyze the CLEO II.V data sample and find the parameters $x$ and $y$ are consistent with zero. We limit $(-4.5<x<9.3)\%$ and $(-6.4<y<3.6)\%$ at the 95% confidence level.

We introduce a new Lorentz-violating modification to a scalar quantum field theory. This interaction, while super-renormalizable by power counting, is fundamentally different from the interactions previously considered within the Lorentz-violating standard model extension. The Lagrange density is nonlocal, because of the presence of a Hilbert transform term; however, this nonlocality is also very weak. The theory has reasonable stability and causality properties and, although the Lorentz-violating interaction possesses a single vector index, the theory is nonetheless CPT even. As an application, we analyze the possible effects of this new form of Lorentz violation on neutral meson oscillations. We find that under certain circumstances, the interaction may lead to quite peculiar sidereal modulations in the oscillation frequency.

In this paper we elaborate on the idea of an emergent spacetime which arises due to the dynamical breaking of diffeomorphism invariance in the early universe. In preparation for an explicit symmetry breaking scenario, we consider nonlinear realizations of the group of analytical diffeomorphisms which provide a unified description of spacetime structures. We find that gravitational fields, such as the affine connection, metric, and coordinates, can all be interpreted as Goldstone fields of the diffeomorphism group. We then construct a Higgs mechanism for gravity in which an affine spacetime evolves into a Riemannian one by the condensation of a metric. The symmetry breaking potential is identical to that of hybrid inflation but with the noninflaton scalar extended to a symmetric second-rank tensor. This tensor is required for the realization of the metric as a Higgs field. We finally comment on the role of Goldstone coordinates as a dynamical fluid of reference.

Motivated by a recent change in viewing the onset of the extragalactic component in the cosmic ray spectrum, we have fitted the observed data down to ${10}^{8.6}\mathrm{GeV}$ and have obtained the corresponding power emissivity. This transition energy is well below the threshold for resonant $p\gamma$ absorption on the cosmic microwave background, and thus source evolution is an essential ingredient in the fitting procedure. Two-parameter fits in the spectral and redshift evolution indices show that a standard Fermi $E_i^{-2}$ source spectrum is excluded at larger than 95% confidence level (CL). Armed with the primordial emissivity, we follow Waxman and Bahcall to derive the associated neutrino flux on the basis of optically thin sources. For $pp$ interactions as the generating mechanism, the neutrino flux exceeds the AMANDA-B10 90% CL upper limits. In the case of $p\gamma$ dominance, the flux is consistent with AMANDA-B10 data. In the new scenario the source neutrino flux is considerably enhanced, especially below ${10}^9\mathrm{GeV}$. Should data from AMANDA-II prove consistent with the model, we show that IceCube can measure the characteristic power law of the neutrino spectrum, and thus provide a window on the source dynamics.

The $1/N_c$ expansion for the baryon distribution amplitude is constructed in terms of a specially designed generating functional. At large $N_c$ this functional shows exponential behavior. The exponential factor is universal for all low-lying baryons and baryon-meson scattering states. Simple factorization properties are established for the preexponential term. This factorization agrees with the large-$N_c$ contracted $SU(2N_f)$ spin-flavor symmetry. The consistency of the factorization with the soft-pion theorem for the baryon distribution amplitude is explicitly checked. A relation between the generating functionals for the distribution amplitudes of the nucleon and the $\Delta$ resonance is derived.

We use an effective-field-theory approach to construct models with naturally light sterile neutrinos, due to either exact or accidental global symmetries. The most attractive models we find are based on gauge symmetries, either discrete or continuous. We give examples of simple models based on ${\mathbf{Z}}_N$, $\mathrm{U}(1{)}^{\prime }$, and $\mathrm{SU}(2{)}^{\prime }$.

The low-energy structure of the energy momentum tensor in several chiral quark models with SU(3) flavor symmetry is analyzed in the presence of external gravitational fields. To this end a derivative expansion in a curved four dimensional space-time is considered. This allows us to compute the chiral coefficients $L_{11}$, $L_{12}$, and $L_{13}$, appearing when the model is coupled to gravity and related to space-time curvature properties.