In this paper, we investigate the nucleon-antinucleon static energies in the Skyrme model with the product Anzatz. The calculation shows that, in the ungroomed $S\overline{S}$ (Skyrmion and anti-Skyrmion) channel which leads to rapid annihilation, there exists a quasistable bound state which may give a natural explanation for the near-threshold enhancement in the proton-antiproton $(p\overline{p})$ mass spectrum reported by the BES Collaboration and the Belle Collaboration. Similar to the phenomenological well potential of the deuteron, we construct a phenomenological Skyrmion-type potential to study this narrow $p\overline{p}$-resonance in $J/\psi \to \gamma p\overline{p}$. By this potential model, a $p\overline{p}$ baryonium with small binding energies is suggested and the decay width of this state is calculated by WKB approximation. In this picture the decay is attributed to quantum tunneling and $p\overline{p}$ annihilation. Prediction on the decay mode from the baryonium annihilation at rest is also pointed out.

The masses of the ground state heavy baryons consisting of two light ($u,d,s$) and one heavy ($c,b$) quarks are calculated in the heavy-quark–light-diquark approximation within the constituent quark model. The light quarks, forming the diquark, and the light diquark in the baryon are treated completely relativistically. The expansion in $v/c$ up to the second order is used only for the heavy ($b$ and $c$) quarks. The diquark-gluon interaction is taken modified by the form factor describing the light diquark structure in terms of the diquark wave functions. An overall reasonable agreement of the obtained predictions with available experimental data and previous theoretical results is found.

Despite the apparent simplicity of meson spectroscopy, light scalar mesons cannot be accommodated in the usual $q\overline{q}$ structure. We study the description of the scalar mesons below 2 GeV in terms of the mixing of a chiral nonet of tetraquarks with conventional $q\overline{q}$ states. A strong diquark-antidiquark component is found for several states. The consideration of a glueball as dictated by quenched lattice QCD drives a coherent picture of the isoscalar mesons.

The decays of nonstrange positive parity excited baryons via emission of a pseudoscalar meson are studied in the framework of the $1/N_c$ expansion to order $1/N_c$. In particular, the pionic decays of the $\ell =0$ Roper baryons and of the $\ell =2$ baryons in the mass interval 1680–1950 MeV are analyzed using the available partial decay widths. Decay widths by emission of an $\eta$ meson are shown to be suppressed by a factor $1/N_c^2$ with respect to the pionic ones.

We present a $2.5\sigma$ detection of the Integrated Sachs-Wolfe (ISW) effect and discuss the constraints it places on cosmological parameters. We cross correlate microwave temperature maps from the Wilkinson microwave anisotropy probe (WMAP) satellite with a $4000{deg}^2$ luminous red galaxy (LRG) overdensity map measured by the Sloan Digital Sky Survey. These galaxies have accurate photometric redshifts ($\Delta z\sim 0.03$) and an approximately volume limited redshift distribution from $z\sim 0.2$ to $z\sim 0.6$ well suited to detecting the ISW effect. Accurate photometric redshifts allow us to perform a reliable autocorrelation analysis of the LRGs, eliminating the uncertainty in the galaxy bias, and combined with the cross correlation signal, constrains cosmological parameters—in particular, the matter density. We use a minimum-variance power spectrum estimator that optimally weights the data according to expected theoretical templates. We find a $2.5\sigma$ signal in the Ka, Q, V, and W WMAP bands, after combining the information from multipoles $2\le l<400$. This is consistent with the expected amplitude of the ISW effect but requires a lower matter density than is usually assumed: the amplitude, parametrized by the galaxy bias assuming ${\Omega }_M=0.3$, ${\Omega }_{\Lambda }=0.7$, and ${\sigma }_8=0.9$, is $b_g=4.05\pm 1.54$ for V band, with similar results for the other bands. This should be compared to $b_g=1.82\pm 0.02$ from the autocorrelation analysis. These data provide only a weak confirmation ($2.5\sigma$) of dark energy but provide a significant upper limit: ${\Omega }_{\Lambda }={0.80}_{-0.06}^{+0.03}(1\sigma {)}_{-0.19}^{+0.05}(2\sigma )$, assuming a cosmology with ${\Omega }_M+{\Omega }_{\Lambda }=1$, ${\Omega }_b=0.05$, ${\sigma }_8=0.9$, and $w=-1$. The weak cross correlation signal rules out low matter density/high dark energy density universes and, in combination with other data, strongly constrains models with $w<-1.3$. We provide a simple prescription to incorporate these constraints into cosmological parameter estimation methods for $({\Omega }_M,{\sigma }_8,w)$. We find no evidence for a systematic contamination of ISW signal, either from galactic or extragalactic sources, but we do detect some large statistical fluctuations on smaller scales that could affect analyses without the template weighting.

Many astrophysical phenomena exhibit relativistic radiative flows. While velocities in excess of $v\sim 0.1c$ can occur in these systems, it has been common practice to approximate radiative transfer to $\mathcal{O}(v/c)$. In the case of neutrino transport in core-collapse supernovas, this approximation gives rise to an inconsistency between lepton number transfer and lab-frame energy transfer, which have different $\mathcal{O}(v/c)$ limits. A solution used in spherically symmetric $\mathcal{O}(v/c)$ simulations has been to retain, for energy accounting purposes, the $\mathcal{O}(v^2/c^2)$ terms in the lab-frame energy transfer equation that arise from the $\mathcal{O}(v/c)$ neutrino number transport equation. Avoiding the proliferation of such extra $\mathcal{O}(v^2/c^2)$ terms in the absence of spherical symmetry motivates a special relativistic formalism, which we exhibit in coordinates sufficiently general to encompass Cartesian, spherical, and cylindrical coordinate systems.

A group of transformations changing the phases of the elements of the single-particle density matrix, but leaving unchanged the predictions for identical particles concerning the momentum distributions, momentum correlations etc., is identified. Its implications for the determinations of the interaction regions from studies of Bose-Einstein correlations are discussed.

We discuss indirect manifestations of graviton exchange, predicted by large extra dimensions, in fermion-pair production at a high-energy $e^{+}{e}^{-}$ collider. By means of specifically defined asymmetries among integrated angular distributions, the graviton exchange signal can be cleanly distinguished from the effects of either vector-vector contact interactions or heavy scalar exchanges. The role of initial electron and positron beams polarization is also discussed. The method is applied to a quantitative assessment of the sensitivity to the mass cutoff parameter $M_H$ of the KK graviton tower in the ADD scenario, and of the potential identification reach of this mechanism obtainable at the currently planned International Linear Collider.

Two- and three-particle distribution amplitudes of heavy pseudoscalar mesons of well-defined geometric twist are introduced. They are obtained from appropriately parametrized vacuum-to-meson matrix elements by applying those twist projectors which determine the enclosed light-cone operators of definite geometric twist and, in addition, observing the heavy quark constraint. Comparing these distribution amplitudes with the conventional ones of dynamical twist we derive relations between them, partially being of Wandzura-Wilczek type; also sum rules of Burkhardt-Cottingham type are derived. The derivation is performed for the (double) Mellin moments and then resummed to the nonlocal distribution amplitudes. Furthermore, a parametrization of vacuum-to-meson matrix elements for nonlocal operators off the light cone in terms of distribution amplitudes accompanying independent kinematical structures is derived.

Analysis of semi-inclusive hadroproduction in deep inelastic scattering suggests broadening of transverse momentum distributions at $x$ below a few ${10}^{-3}$, which can be modeled in the Collins-Soper-Sterman formalism by a modification of impact-parameter-dependent parton densities. We discuss the consequences of such a modification for the production of electroweak bosons at hadron-hadron colliders. If substantial small-$x$ broadening is observed in forward $Z^0$ boson production in the Tevatron Run-2, it will strongly affect predicted $q_T$ distributions for $W^{\pm }$, $Z^0$, and Higgs boson production at the Large Hadron Collider.

It is generally expected that decoherence processes will erase the quantum properties of the inflationary primordial spectra. However, given the weakness of gravitational interactions, one might end up with a distribution which is only partially decohered. Below a certain critical change, we show that the inflationary distribution retains quantum properties. We identify four of these: a squeezed spread in some direction of phase space, nonvanishing off-diagonal matrix elements, and two properties used in quantum optics called non-$P$ representability and nonseparability. The last two are necessary conditions to violate Bell’s inequalities. The critical value above which all these properties are lost is associated with the “grain“ of coherent states. The corresponding value of the entropy is equal to half the maximal (thermal) value. Moreover it coincides with the entropy of the effective distribution obtained by neglecting the decaying modes. By considering backreaction effects, we also provide an upper bound for this entropy at the onset of the radiation dominated era.

We discuss a new class of solutions to the Einstein equations which describe a primordial black hole (PBH) in a flat Friedmann background. Such solutions arise if a Schwarzschild black hole is patched onto a Friedmann background via a transition region. They are possible providing the black hole event horizon is larger than the cosmological apparent horizon. Such solutions have a number of strange features. In particular, one has to define the black hole and cosmological horizons carefully and one then finds that the mass contained within the black hole event horizon decreases when the black hole is larger than the Friedmann cosmological apparent horizon, although its area always increases. These solutions involve two distinct future null infinities and are interpreted as the conversion of a white hole into a black hole. Although such solutions may not form from gravitational collapse in the same way as standard PBHs, there is nothing unphysical about them, since all energy and causality conditions are satisfied. Their conformal diagram is a natural amalgamation of the Kruskal diagram for the extended Schwarzschild solution and the conformal diagram for a black hole in a flat Friedmann background. In this paper, such solutions are obtained numerically for a spherically symmetric universe containing a massless scalar field, but it is likely that they exist for more general matter fields and less symmetric systems.

In this paper, we use the type Ia supernovae data to constrain the holographic dark energy model proposed by Li. We also apply a cosmic age test to this analysis. We consider in this paper a spatially flat Friedmann-Robertson-Walker universe with a matter component and a holographic dark energy component. The fit result shows that the case $c<1$ ($c=0.21$) is favored, which implies that the holographic dark energy behaves as a quintom-type dark energy. Furthermore, we also perform a joint analysis of $\mathrm{SNe}+\mathrm{CMB}+\mathrm{LSS}$ to this model; the result is well improved and still upholds the quintom dark energy conclusion. The best fit results in our analysis are $c=0.81$, ${\Omega }_m^0=0.28$, and $h=0.65$, which lead to the present equation of state of dark energy $w_0=-1.03$ and the deceleration/acceleration transition redshift $z_T=0.63$. Finally, an expected supernova/acceleration probe simulation using $\Lambda \mathrm{CDM}$ as a fiducial model is performed on this model, and the result shows that the holographic dark energy model takes on $c<1$ ($c=0.92$) even though the dark energy is indeed a cosmological constant.

We study analytically and numerically the inflationary solutions for various type scalar potentials in the nonminimally coupled scalar field theory. The Hamilton-Jacobi equation is used to deal with nonlinear evolutions of inhomogeneous spacetimes and the long-wavelength approximation is employed to find the homogeneous solutions during an inflation period. The constraints that lead to a sufficient number of e-folds, a necessary condition for inflation, are found for the nonminimal coupling constant and initial conditions of the scalar field for inflation potentials. In particular, we numerically find an inflationary solution in the new inflation model of a nonminimal scalar field.

We study how the oscillations of the neutrinos affect their thermalization process during the reheating period with temperature $O(1)$ MeV in the early universe. We follow the evolution of the neutrino density matrices and investigate how the predictions of big bang nucleosynthesis vary with the reheating temperature. For the reheating temperature of several MeV, we find that including the oscillations makes different predictions, especially for ${}^4\mathrm{He}$ abundance. Also, the effects on the lower bound of the reheating temperature from cosmological observations are discussed.

Motivated by recent astrophysical observations of quasar absorption systems, we formulate a simple theory where the electron to proton mass ratio $\mu =m_e/m_p$ is allowed to vary in spacetime. In such a minimal theory only the electron mass varies, with $\alpha$ and $m_p$ kept constant. We find that changes in $\mu$ will be driven by the electronic energy density after the electron mass threshold is crossed. Particle production in this scenario is negligible. The cosmological constraints imposed by recent astronomical observations are very weak, due to the low mass density in electrons. Unlike in similar theories for spacetime variation of the fine structure constant, the observational constraints on variations in $\mu$ imposed by the weak equivalence principle are much more stringent constraints than those from quasar spectra. Any time variation in the electron-proton mass ratio must be less than one part in ${10}^9$ since redshifts $z\approx 1$. This is more than 1000 times smaller than current spectroscopic sensitivities can achieve. Astronomically observable variations in the electron-proton must therefore arise directly from effects induced by varying fine structure “constant” or by processes associated with internal proton structure. We also place a new upper bound of $2\times {10}^{-8}$ on any large-scale spatial variation of $\mu$ that is compatible with the isotropy of the microwave background radiation. It is of course possible to bypass these constraints with the addition of a suitable potential to the dynamics.

A detailed study of the high temperature dynamics of the scalar sector of little Higgs scenarios, proposed to stabilize the electroweak scale, shows that the electroweak gauge symmetry remains broken even at temperatures much larger than the electroweak scale. Although we give explicit results for a particular modification of the littlest Higgs model, we expect that the main features are generic. As a spin-off, we introduce a novel way of dealing with scalar fluctuations in nonlinear sigma models, which might be of interest for phenomenological applications.

The exponential sensitivity of cluster number counts to the properties of the dark energy implies a comparable sensitivity to not only the mean but also the actual distribution of an observable-mass proxy given the true cluster mass. For example a 25% scatter in mass can provide a $\sim 50\%$ change in the number counts at $z\sim 2$ for the upcoming SPT survey. Uncertainty in the scatter of this amount would degrade dark energy constraints to uninteresting levels. Given the shape of the actual mass function, the properties of the distribution may be internally monitored by the shape of the observable mass function. As a proof of principle, for a simple mass-independent Gaussian distribution the scatter may be self-calibrated to allow a measurement of the dark energy equation of state of $\sigma (w)\sim 0.1$. External constraints on the mass variance of the distribution that are more accurate than $\Delta {\sigma }_{\ln M}^2<0.01$ at $z\sim 1$ can further improve constraints by up to a factor of 2. More generally, cluster counts and their sample variance measured as a function of the observable provide internal consistency checks on the assumed form of the observable-mass distribution that will protect against misinterpretation of the dark energy constraints.

We formulate and optimize a computational search strategy for detecting gravitational waves from isolated, previously unknown neutron stars (that is, neutron stars with unknown sky positions, spin frequencies, and spin-down parameters). It is well known that fully coherent searches over the relevant parameter-space volumes are not computationally feasible, and so more computationally efficient methods are called for. The first step in this direction was taken by Brady and Creighton (2000), who proposed and optimized a two-stage, stack-slide search algorithm. We generalize and otherwise improve upon the Brady-Creighton scheme in several ways. Like Brady and Creighton, we consider a stack-slide scheme, but here with an arbitrary number of semicoherent stages and with a coherent follow-up stage at the end. We find that searches with three semicoherent stages are significantly more efficient than two-stage searches (requiring about 2–5 times less computational power for the same sensitivity) and are only slightly less efficient than searches with four or more stages. We calculate the signal-to-noise ratio required for detection, as a function of computing power and neutron star spin-down-age, using our optimized searches.

We demonstrate that one could measure the absolute matter density of the Earth’s core with a vertical neutrino factory baseline at the per cent level for ${sin}^{2}2{\theta }_{13}\gtrsim 0.01$, where we include all correlations with the oscillation parameters in the analysis. We discuss the geographical feasibility of such an approach, and illustrate how the results change as a function of the detector location. We point out the complementarity to geophysics.