We investigate the 35-plet baryons from the chiral soliton models. We find that the coupling constant for the decay of 35-plet baryons with spin $3/2$ to the decuplet baryons is surprisingly small, but that for the decay to 27-plet baryons with spin $3/2$ is larger. We give all the masses and widths of 35-plet baryons with spin $5/2$ and suggest candidates for all nonexotic members from the available particle listings. We also focus on ${\Delta }_{5/2}$ and ${\Theta }_2$, which are the lightest two baryons of 35-plet with spin $5/2$ and with simplest minimal pentaquark configurations. Calculations show that ${\Gamma }_{{\Delta }_{5/2}}<380\mathrm{M}\mathrm{e}\mathrm{V}$, compared with the results from the SU(2) Skyrme model (${\Gamma }_{{\Delta }_{5/2}}>800\mathrm{M}\mathrm{e}\mathrm{V}$), and ${\Gamma }_{{\Theta }_2}<100\mathrm{M}\mathrm{e}\mathrm{V}$ if we assume that their widths are dominated by two-body decay and that ${\Theta }^{+}$ has a width ${\Gamma }_{{\Theta }^{+}}<25\mathrm{M}\mathrm{e}\mathrm{V}$.

Four separate experiments [A. Etkin et al., Phys. Rev. Lett. 41, 784 (1978).][A. Etkin et al., Phys. Rev. Lett. 49, 1620 (1982).][A. Etkin et al., Phys. Lett. B 165, 217 (1985).][A. Etkin et al., Phys. Lett. B 201, 568 (1988).] observing the OZI forbidden disconnected reaction ${\pi }^{-}p\to \varphi \varphi n$ with increasing statistics were consistent. These experiments, very selectively, completely broke down the OZI suppression by three $\varphi \varphi$ resonances with $I^G{J}^{PC}=0^{+}{2}^{++}$ in the observed mass region 2.038 GeV to 2.600 GeV. The only viable proposed explanation has been that the $I^G{J}^{PC}=0^{+}{2}^{++}$ glueball expected in this mass region caused the hard glue in the disconnection to resonate and very selectively break down the OZI suppression for its quantum numbers only. Recently a $pp$ central production spin analysis found that the $f_2(1950)$ had a dominant decay mode $f_2(1270)\pi \pi$ [D. Barberis et al., Phys. Lett. B 471, 440 (2000).]). We consider if it is related to the $\varphi \varphi$ resonances, and find that it likely is.

We use local quark-hadron duality to calculate the nucleon structure function as seen by neutrino and muon beams. Our result indicates a possible signal of charge symmetry violation at the parton level in the very large $x$ region.

A model for the twist-3 wave function ${\psi }_p(x,{\mathbf{k}}_{\perp })$ of the pion has been constructed based on the moment calculation by applying the QCD sum rules, whose distribution amplitude has a better end-point behavior than that of the asymptotic one. With this model wave function, the twist-3 contributions including both the usual helicity components (${\lambda }_1+{\lambda }_2=0$) and the higher helicity components (${\lambda }_1+{\lambda }_2=\pm 1$) to the pion form factor have been studied within the modified pQCD approach. Our results show that the twist-3 contribution drops fast and it becomes less than the twist-2 contribution at $Q^2\sim 10\mathrm{G}\mathrm{e}{\mathrm{V}}^2$. The higher helicity components in the twist-3 wave function will give an extra suppression to the pion form factor. The model dependence of the twist-3 contribution to the pion form factor has been studied by comparing four different models. When all the power contributions, which include higher order in ${\alpha }_s$, higher helicities, higher twists in DA and, etc., have been taken into account, it is expected that the hard contributions will fit the present experimental data well at the energy region where pQCD is applicable.

It is shown that the charged massive Schwinger model supports a periodic vacuum structure for arbitrary charge density, similar to the common crystalline layout known in solid state physics. The dynamical origin of the inhomogeneity is identified in the framework of the bosonized model and in terms of the original fermionic variables.

Arguments for black hole formation in collisions of high-energy particles have rested on the emergence of a closed trapped surface in the classical geometry of two colliding Aichelburg-Sexl solutions. Recent analysis has, however, shown that curvatures and quantum fluctuations are large on this apparent horizon, potentially invalidating a semiclassical analysis. We show that this problem is an artifact of the unphysical classical point-particle limit: for a particle described by a quantum wavepacket, or for a continuous matter distribution, trapped surfaces indeed form in a controlled regime.

We examine the nonperturbative structure of the radiatively induced Chern-Simons term in a Lorentz- and CPT-violating modification of QED. Although the coefficient of the induced Chern-Simons term is in general undetermined, the nonperturbative theory appears to generate a definite value. However, the CPT-even radiative corrections in this same formulation of the theory generally break gauge invariance. We show that gauge invariance may yet be preserved through the use of a Pauli-Villars regulator, and, contrary to earlier expectations, this regulator does not necessarily give rise to a vanishing Chern-Simons term. Instead, two possible values of the Chern-Simons coefficient are allowed, one zero and one nonzero. This formulation of the theory therefore allows the coefficient to vanish naturally, in agreement with experimental observations.

We compute the dimension-2 condensate $⟨A^2⟩$ and dimension-4 mixed condensate $⟨\overline{q}\mathrm{A̸}q⟩$ from the recent quenched lattice results for the quark propagator in the Landau gauge. We fit the lattice data to the Operator Product Expansion in the fiducial region $1.2\mathrm{G}\mathrm{e}\mathrm{V}\le Q\le 3\mathrm{G}\mathrm{e}\mathrm{V}$. Our result for the dynamical gluon mass at the scale of $10{\mathrm{G}\mathrm{e}\mathrm{V}}^2$ is $m_A=600–650\mathrm{M}\mathrm{e}\mathrm{V}$, in agreement with independent determinations. For the dimension-4 mixed Landau-gauge condensate we get ${\alpha }_s⟨\overline{q}g\mathrm{A̸}q⟩=(-0.11\pm 0.03){\mathrm{G}\mathrm{e}\mathrm{V}}^4$. This value is an order of magnitude larger than the $⟨G^2⟩$ gluon condensate.

A model for the dressed-quark-gluon vertex, at zero gluon momentum, is formed from a nonperturbative extension of the two Feynman diagrams that contribute at one loop in perturbation theory. The required input is an existing ladder-rainbow model Bethe-Salpeter kernel from an approach based on the Dyson-Schwinger equations; no new parameters are introduced. The model includes an Ansatz for the triple-gluon vertex. Two of the three vertex amplitudes from the model provide a pointwise description of the recent quenched-lattice-QCD data. An estimate of the effects of quenching is made.

We develop a calculation scheme in Coulomb and temporal gauge that respects gauge invariance and is most easily applied to the infrared asymptotic region of QCD. It resembles the Dyson-Schwinger equations of Euclidean quantum field theory in Landau gauge, but is three dimensional. A simple calculation yields a color-Coulomb potential that behaves at large $R$ approximately like $V_{\mathrm{c}\mathrm{o}\mathrm{u}\mathrm{l}}(R)\sim R^{[1-0.2(d-1)]}$ for spatial dimension $1\le d\le 3$. This is a linearly rising potential plus a rather weak dependence on $d$.

We integrate out fast varying quantum fluctuations around static $A_4$ and $A_i$ fields for the $\mathrm{S}\mathrm{U}(N)$ gauge group. By assuming that the gluon fields are slowly varying but allowing for an arbitrary amplitude of $A_4$ we obtain two variants of the effective high-temperature theory for the Polyakov line. One is the effective action for the gauge-invariant eigenvalues of the Polyakov line, and it is explicitly $\mathrm{Z}(N)$ symmetric. The other is the effective action for the Polyakov line itself as an element of the $\mathrm{S}\mathrm{U}(N)$. In this case the theory necessarily includes the spatial components $A_i$ to ensure its gauge invariance under spatial gauge transformations. We derive the 1-loop effective action in the electric and magnetic sectors, summing up all powers of $A_4$.

At high energies on a cosmological brane of Randall-Sundrum type, particle interactions can produce gravitons that are emitted into the bulk and that can feed a bulk black hole. We generalize previous investigations of such radiating brane-worlds by allowing for a breaking of $Z_2$ symmetry via different bulk cosmological constants and different initial black hole masses on either side of the brane. One of the notable features of asymmetry is a suppression of the asymptotic level of dark radiation, which means that nucleosynthesis constraints are easier to satisfy. There are also models where the radiation escapes to infinity on one or both sides, rather than falling into a black hole, but these models can have negative energy density on the brane.

We study the late time behavior of a universe in the framework of brane gas cosmology. We investigate the evolution of a universe with a gas of supergravity particles and a gas of branes. Considering the case when different dimensions are anisotropically wrapped by various branes, we have derived Friedmann-like equations governing the dynamics of wrapped and unwrapped subvolumes. We point out that the compact internal dimensions are wrapped by three or higher dimensional branes.

The theoretical construction of a traversable wormhole from a Schwarzschild black hole is described, using analytic solutions in Einstein gravity. The matter model is pure phantom radiation (pure radiation with negative-energy density) and the idealization of impulsive radiation is employed.

We calculate the influence of the ’t Hooft interaction on the single-charm ($\mathrm{C}=1$) tetraquark ($cq{\overline{q}}^2$) mass spectrum and find that three SU(3)-flavor multiplets (${\overline{\mathbf{3}}}_{\mathbf{A}},\mathbf{6},\overline{\mathbf{15}}$) are significantly lowered, while the ${\overline{\mathbf{3}}}_{\mathbf{S}}$-plet is lifted, as compared with their unperturbed masses. States with the $D_s^{+}$ quantum numbers appear in two of the three lowered multiplets. The lower of the two states drops below both of the Okubo-Zweig-Iizuka (OZI)-allowed decay thresholds, thus being identified with $D_s^{*+}(2320)$, while the heavier state drops below the $\eta +D_s^{+}$ threshold, but stays above the $K+D$ one. A signature prediction of this theory is the lowering of the exotic tetraquark $\mathbf{6}$-plet and $\overline{\mathbf{15}}$-plet: most of these states cannot consist of only one quark and one antiquark. As a test we suggest a search for two quasistable exotic tetraquarks with open-charm and strangeness: the (isotriplet) $cs\overline{q}\overline{q}$ and the (isodoublet) $cq\overline{s}\overline{s}$.

We compute the two-loop virtual corrections to the flavor changing neutral current process $b\to d{\ell }^{+}{\ell }^{-}$. As calculation techniques, integration by parts identities and the method of differential equations are used. The result is presented in closed form as a function of $q^2/m_b^2$, where $q^2$ is the invariant mass of the lepton pair and $m_b$ is the $b$-quark mass.

In this paper, we derive the cross section formula for the Higgs pair production at a linear $e^{+}{e}^{-}$ collider in models with large extra dimensions and study the feasibility of its measurement through realistic Monte Carlo simulations. Since the process has essentially no standard model background, once produced, it will provide us with a very clean signature of physics beyond the standard model. Moreover, since the final-state particles are spinless, the spin-2 of the intermediate virtual Kaluza-Klein (KK) gravitons has to be conserved by the orbital angular momentum of the Higgs pair. This results in a very characteristic angular distribution of the final states. Taking into account finite detector acceptance and resolutions as well as initial-state radiation and beamstrahlung, we demonstrate in this paper that, given a sufficiently high center of mass energy, the angular distribution of the Higgs pair is indeed measurable at the linear collider and will allow us to prove the spin-2 nature of the KK gravitons exchanged in the $s$ channel.

We calculate the angles of deflection of high-speed particles projected in an arbitrary direction into the Kerr gravitational field. This is done by first calculating the lightlike boost of the Kerr gravitational field in an arbitrary direction and then using this boosted gravitational field as an approximation to the gravitational field experienced by a high-speed particle. In the rest frame of the Kerr source the angles of deflection experienced by the high-speed test particle can then easily be evaluated.

A simple relationship of the form $Z_{\mathrm{B}\mathrm{H}}=|Z_{\mathrm{t}\mathrm{o}\mathrm{p}}{|}^2$ is conjectured, where $Z_{\mathrm{B}\mathrm{H}}$ is a supersymmetric partition function for a four-dimensional BPS black hole in a Calabi-Yau compactification of Type II superstring theory and $Z_{\mathrm{t}\mathrm{o}\mathrm{p}}$ is a second-quantized topological string partition function evaluated at the attractor point in moduli space associated to the black hole charges. Evidence for the conjecture in a perturbation expansion about large graviphoton charge is given. The microcanonical ensemble of BPS black holes can be viewed as the Wigner function associated to the wave function defined by the topological string partition function.

The quantum theory involving noncommutative tensionless $p$-branes is studied following path integral methods. Our procedure allows a simple treatment for generally covariant noncommutative extended systems and it contains, as a particular case, the thermodynamics and the quantum tensionless string theory. The effect induced by noncommutativity in the field space is to produce a confinement among pairing of null $p$-branes.