A simple analytic expression for the nonsinglet structure function $f_{\mathrm{NS}}$ is given. The expression is derived from the result of Ermolaev, Manaenkov, and Ryskin obtained by low x resummation of the quark ladder diagrams in the double logarithmic approximation of perturbative QCD.

“Little Higgs” models, in which the Higgs particle arises as a pseudo Goldstone boson, have a natural mechanism of electroweak symmetry breaking associated with the large value of the top quark Yukawa coupling. The mechanism typically involves a new heavy $\mathrm{SU}{\mathrm{}\left(2\right)\mathrm{}}_L$ singlet top quark T. We discuss the relationship of the Higgs boson and the two top quarks. We suggest experimental tests of the little Higgs mechanism of electroweak symmetry breaking using the production and decay of the T at the CERN Large Hadron Collider.

Quenched QCD simulations on three volumes $8^3\times ,$ ${12}^3\times$ and ${16}^3\times 32$ and three couplings $\beta =5.7,$ 5.85 and 6.0 using domain wall fermions provide a consistent picture of quenched QCD. We demonstrate that the small induced effects of chiral symmetry breaking inherent in this formulation can be described by a residual mass ${(m}_{\mathrm{res}})$ whose size decreases as the separation between the domain walls ${(L}_s)$ is increased. However, at stronger couplings much larger values of $L_s$ are required to achieve a given physical value of $m_{\mathrm{res}}.$ For $\beta =6.0\mathrm{}$ and $L_s=16,$ we find $m_{\mathrm{res}}{/m}_s=0.033\mathrm{}\left(3\right),$ while for $\beta =5.7,$ and $L_s=48,$ $m_{\mathrm{res}}{/m}_s=0.074\mathrm{}\left(5\right),$ where $m_s$ is the strange quark mass. These values are significantly smaller than those obtained from a more naive determination in our earlier studies. Important effects of topological near zero modes which should afflict an accurate quenched calculation are easily visible in both the chiral condensate and the pion propagator. These effects can be controlled by working at an appropriately large volume. A non-linear behavior of $m_{\pi }^2$ in the limit of small quark mass suggests the presence of additional infrared subtlety in the quenched approximation. Good scaling is seen both in masses and in $f_{\pi }$ over our entire range, with inverse lattice spacing varying between 1 and 2 GeV.

The recently discovered narrow charmonium resonance near 3870 MeV is interpreted as a hadronic molecule whose constituents are the charm mesons $D^0$ and $D^{*0}$ or $D^0$ and $D^{*0}.$ Because of an accidental fine-tuning of the molecule to very near the $D^0{D}^{*0}$ threshold, it has some universal properties that are completely determined by the unnaturally large $D^0{D}^{*0}$ scattering length a. Its narrow width can be explained by the suppression by a factor of $1/a$ of decay modes other than the decay of a constituent $D^{*0}$ or $D^{*0}.$ Its production rates are also suppressed by a factor of $1/a.$ A particularly predictive mechanism for generating the large scattering length is the accidental fine-tuning of a P-wave charmonium state to the $D^0{D}^{*0}$ threshold.

$\overrightarrow{\tau }\pi \pi \pi {\nu }_{\tau }$ decays are analyzed within the framework of the resonance effective theory of QCD. We work out the relevant Lagrangian that describes the axial-vector current hadronization contributing to these processes, in particular the local $a_1\mathrm{}\left(1260\right)-\rho \mathrm{}\left(770\right)\mathrm{}$-Goldstone interactions. The new coupling constants are constrained by imposing the asymptotic behavior of the corresponding spectral function within QCD. Hence we compare the theoretical framework with the experimental data, obtaining a good quality fit from the ALEPH spectral function and branching ratio. We also get values for the mass and on-shell width of the $a_1\mathrm{}\left(1260\right)\mathrm{}$ resonance. In this way we are able to provide the structure functions that have been measured by OPAL and CLEO-II and we find an excellent agreement.

We consider the massive Dirac neutrino electric charge and magnetic moment within the context of the standard model supplied with an SU(2)-singlet right-handed neutrino in an arbitrary $R_{\xi }$ gauge. Using the dimensional-regularization scheme we start with the calculations of the one-loop contributions to the neutrino electromagnetic vertex function exactly accounting for the neutrino mass. We examine the decomposition of the massive neutrino electromagnetic vertex function. It is found by means of direct calculations that the massive neutrino vertex function contains only the four form factors. Then we derive the closed integral expressions for different contributions to the neutrino electric form factor, electric charge, and magnetic moment. For several one-loop contributions to the neutrino charge and magnetic moment that were calculated previously with mistakes by the other authors, we find the correct results. We show that the electric charge for the massive neutrino is a gauge independent and vanishing parameter in the first two orders of the expansion over the neutrino mass parameter ${b=(m}_{\nu }{/M}_W{)}^2.$ From the obtained closed two-integral expression for a massive neutrino electric form factor it is also possible to derive the neutrino charge radius. In the particular choice of the ’t Hooft–Feynman gauge we also demonstrate that the neutrino charge is zero in all orders of expansion over b, i.e., for an arbitrary mass of neutrino. For each of the diagrams contributing to the neutrino magnetic moment, we obtain the expressions accounting for the leading (zeroth) and next-to-leading (first) order in b, where the gauge dependence is shown explicitly. Each of the contributions is finite and the sum of all contributions turns out to be gauge independent. Our calculations also enable us to obtain the neutrino magnetic moment in theoretical models that differ from each other by the values of particles’ masses, including the case of a very heavy neutrino. The general expression for the massive neutrino magnetic form factor is presented.

We present extensive results and analysis of energy and angular distributions of diffuse UHE ${\nu }_e,$ ${\nu }_{\mu },$ and ${\nu }_{\tau }$ fluxes propagated through Earth, with and without augmentation of the standard model interactions by low scale gravity. With propagated fluxes in hand we estimate event rates in a $1{\mathrm{km}}^3$ detector in ice with characteristics of ICECUBE. We determine that, at an 0.5 PeV energy threshold, there is a significant difference in the ratios of down shower events to upward muon events between the standard model and the low scale gravity cases with 1 TeV and 2 TeV mass scales. The same is true for the energy threshold at 5 PeV. Though the difference is large in all flux models, the statistical significance of this difference depends on the flux models, especially at 5 PeV and above. Both flavor assumptions, ${\nu }_e,$ ${\nu }_{\mu },$ ${\nu }_{\tau }::1,$ 2, 0 and ${\nu }_e,$ ${\nu }_{\mu },$ ${\nu }_{\tau }::1,$ 1, 1, and all flux models show large differences. Though rates of tagged events are low, we find that ${\nu }_{\tau }$ regeneration by $\tau$ decay may play an important role in disclosing deviations from standard model predictions at energies in the neighborhood of 1 PeV for 1-TeV-scale gravity, for example. We emphasize those analyses whose sensitivity to new physics is independent of the flux model assumed.

In this paper we consider a q-deformed scalar quantum field theory and show that this theory is renormalizable up to second order in the coupling constant. This result is obtained in a similar way to the nondeformed standard theory.

The Casimir energy is evaluated for massless scalar fields under Dirichlet or Neumann boundary conditions, and for the electromagnetic field with perfect conductor boundary conditions on one and two infinite parallel plates moving by uniform proper acceleration through the Fulling-Rindler vacuum in an arbitrary number of spacetime dimensions. For the geometry of a single plate both regions of the right Rindler wedge, (i) on the right (RR region) and (ii) on the left (RL region), of the plate are considered. The zeta function technique is used, in combination with contour integral representations. The Casimir energies for separate RR and RL regions contain pole and finite contributions. For an infinitely thin plate taking RR and RL regions together, in odd spatial dimensions the pole parts cancel and the Casimir energy for the whole Rindler wedge is finite. In $d=3\mathrm{}$ spatial dimensions the total Casimir energy for a single plate is negative for Dirichlet scalar and positive for Neumann scalar and the electromagnetic field. The total Casimir energy for two plates geometry is presented in the form of a sum of the Casimir energies for separate plates plus an additional interference term. The latter is negative for all values of the plates separation for both Dirichlet and Neumann scalars, and for the electromagnetic field.

We discuss a spontaneous baryogenesis mechanism in flat directions. After identifying the Nambu-Goldstone mode which derivatively couples to the associated $U\left(1\right)\mathrm{}$ current and rotates due to the A term, we show that spontaneous baryogenesis can be naturally realized in the context of the flat direction. As applications, we discuss two scenarios of baryogenesis in detail. One is baryogenesis in a flat direction with a vanishing $B-L$ charge, especially with neither baryon nor lepton charge, which was recently proposed by Chiba and the present authors. The other is a baryogenesis scenario compatible with a large lepton asymmetry.

We study the secular variation of the period of nonradial pulsations of white dwarfs when a temporal dependence of the gravitational constant G is assumed. We consider models that reproduce accurately the main characteristics of the best studied DA (hydrogen-rich atmosphere) white dwarf G117-B15A. For this object it has been possible to measure the secular variation of the main observed period of 215.2 s $(\mathrm{Ṗ}=2.3\mathrm{}\pm 1.4\times {10}^{-15}{\mathrm{s}}^{-1})$ with unprecedented accuracy. Comparing our models with observations we obtain that for $Ġ<0\mathrm{}$ the allowed values are in the range $-2.5\times {10}^{-10}{\mathrm{yr}}^{-1}\lesssim Ġ/G\lesssim 0,$ whereas, for $Ġ>0,$ the allowed values are $0\lesssim Ġ/G\lesssim 4.0\times {10}^{-11}{\mathrm{yr}}^{-1}$ at the $2\sigma$ confidence level, which are comparable to other bounds established by independent methods. We also show that in order to improve this bound significantly an improvement in the precision of the observed change in $\mathrm{Ṗ}$ which is too large to be reached in the foreseeable future is required.

We use the perturbation method to calculate the masses and widths for 27-plet baryons with spin $\frac{3}{2}$ from chiral soliton models. According to the masses and quantum numbers, we find all the candidates for nonexotic members of the 27-plet. The calculation of the widths shows that these candidates manifest an approximate symmetry of the 27 representation of the SU(3) group, and the quantum numbers of $\Xi \mathrm{}\left(1950\right)\mathrm{}$ seem to be ${I(J}^P)=\frac{1}{2}({\frac{3}{2}}^{+}).\mathrm{}$ Up to leading order of the strange quark mass, we find that the exotic members have widths much larger than those of the antidecuplet members.

We study the analytic structure of light-front wave functions (LFWFs) and its consequences for hadron form factors using an explicitly Lorentz-invariant formulation of the front form. The normal to the light front is specified by a general null vector ${\omega }^{\mu }.$ The LFWFs with definite total angular momentum are eigenstates of a kinematic angular momentum operator and satisfy all Lorentz symmetries. They are analytic functions of the invariant mass squared of the constituents $M_0^2=(\sum k^{\mu }{)}^2$ and the light-cone momentum fractions $x_i{=k}_i\cdot \omega /p\cdot \omega$ multiplied by invariants constructed from the spin matrices, polarization vectors, and ${\omega }^{\mu }.$ These properties are illustrated using known nonperturbative eigensolutions of the Wick-Cutkosky model. We analyze the LFWFs introduced by Chung and Coester to describe static and low momentum properties of the nucleons. They correspond to the spin locking of a quark with the spin of its parent nucleon, together with a positive-energy projection constraint. These extra constraints lead to an anomalous dependence of form factors on Q rather than $Q^2.$ In contrast, the dependence of LFWFs on $M_0^2$ implies that hadron form factors are analytic functions of $Q^2$ in agreement with dispersion theory and perturbative QCD. We show that a model incorporating the leading-twist perturbative QCD prediction is consistent with recent data for the ratio of proton Pauli and Dirac form factors.

We calculate the magnetic moment of the recently observed ${\Theta }^{+}$ pentaquark state in the framework of the light cone QCD sum rules using the photon distribution amplitudes. We find that ${\mu }_{{\Theta }^{+}}=(0.12\mathrm{}\pm 0.06){\mu }_N,$ which is quite small. We also compare our result with predictions of other groups.

Inclusive momentum spectra and multiplicity distributions of charged particles measured with the BESII detector at center of mass energies of 2.2, 2.6, 3.0, 3.2, 4.6 and 4.8 GeV are presented. Values of the second binomial moment $R_2$ obtained from the multiplicity distributions are reported. These results are compared with both experimental data from high energy $e^{+}{e}^{-},$ ep, and $p\overline{p}$ experiments and QCD calculations.

Using a $13.7{\mathrm{fb}}^{-1}$ data sample collected with the CLEO II and II.V detectors, we report new branching fraction measurements for two Cabibbo-suppressed decay modes of the $D^{+}$ meson: $\mathcal{B}{(D}^{+}\to {\pi }^{+}{\pi }^0)=(1.31\mathrm{}\pm 0.17\pm 0.09\pm 0.09)\times {10}^{-3}$ and $\mathcal{B}{(D}^{+}\to K^{+}{K}^0)=(5.24\mathrm{}\pm 0.43\pm 0.20\pm 0.34)\times {10}^{-3}$ which are significant improvements over past measurements. The errors reflect statistical and systematical uncertainties as well as the uncertainty in the absolute $D^{+}$ branching fraction scale. We also set the first 90% confidence level upper limit on the branching fraction of the doubly Cabibbo-suppressed decay mode $\mathcal{B}{(D}^{+}\to K^{+}{\pi }^0)<\mathrm{}4.2\mathrm{}\times {10}^{-4}.$

We recently derived exact solutions for the scalar, vector, and tensor mode functions of a single, minimally coupled scalar plus gravity in an arbitrary homogeneous and isotropic background. These solutions are applied to obtain improved estimates for the primordial scalar and tensor power spectra of anisotropies in the cosmic microwave background.

Can local fluctuations of a “quintessence” scalar field play a dynamical role in the gravitational clustering and cosmic structure formation process? We address this question in the general framework of scalar-tensor theories of gravity. Nonlinear energy density perturbations, both in the scalar field and matter component, and linear metric perturbations are accounted for in the perturbed Einstein equations. We derive the Newtonian limit of the relevant equations for clustering in scalar-tensor cosmologies. We then specialize to nonlinear perturbations of the “extended quintessence” model of dark energy; in such a model, a nonminimally coupled scalar field is thought to be responsible for driving the present accelerated phase of the Universe expansion. The interplay between dark energy and dark matter is displayed in the equations governing the growth of structure in the Universe.

We generalize a recently proposed mechanism for the origin of primordial metric perturbations in inflationary models. Quantum fluctuations of light scalar fields during inflation gives rise to superhorizon fluctuations of masses and reaction rates of various particles. Reheating, freeze-out, and matter-domination processes become inhomogeneous and generate superhorizon metric perturbations. We also calculate the degree of non-Gaussianity $f_{\mathrm{nl}}$ for this new model of cosmological perturbations. The precise value of $f_{\mathrm{nl}}$ depends on the specific models, but $|f_{\mathrm{nl}}|\sim \mathrm{few}$ is a natural lower bound for our mechanisms. This is much larger than the currently assumed theoretical value $f_{\mathrm{nl}}\sim \mathrm{tilt}\lesssim 0.05,$ and is thought to be observable. In a particularly attractive model of inhomogeneous mass domination, the non-Gaussianity of perturbations generated by our mechanism is simply $f_{\mathrm{nl}}=5,$ irrespective of the detailed structure of the underlying field theory.

Gauge invariant quintessence perturbations in the quintessence and cold dark matter model are investigated. For three cases of a constant equation-of-state (EOS) parameter, linear scalar field potential, and supergravity scalar field potential, their perturbation evolutions have a similar dependence on the EOS parameter and scale, but they have different sensitivity to the initial conditions due to the different shapes of the quintessence potential. They have a minor effect on primary cosmic microwave background (CMB) anisotropies but change the secondary CMB effect in different ways. The first case is insensitive to initial quintessence perturbations and modifies only the integrated Sachs-Wolfe effect within a factor of 2. The other two cases are sensitive to initial conditions at large scales and could affect the secondary CMB anisotropies drastically depending on how smooth the initial perturbations are. This makes it possible for future cosmological probes to provide constraints on quintessence properties.