We study the associated production of the charged Higgs boson and $W^{\pm }$ gauge boson in high energy $e^{+}{e}^{-}$ collisions in the minimal supersymmetric standard model (MSSM). This associated production, which first arises at the one loop level, offers the possibility of producing the charged Higgs boson at the $e^{+}{e}^{-}$ collider with a mass more than half the center-of-mass energy, when the charged Higgs pair production is kinematically forbidden. We present analytic and numerical results for the cross section for $e^{+}{e}^{-}\to W^{+}{H}^{-}$ in the full MSSM, taking into account the previously uncalculated contributions from supersymmetric (SUSY) particles. We find that the contributions of the SUSY particles enhance the cross section over most of SUSY parameter space, especially when the SUSY particles are light, $\sim 200\hspace{0.5em}\mathrm{GeV}.$ With favorable SUSY parameters, at small $\tan \beta ,$ this process can yield more than ten $W^{\pm }{H}^{\mp }$ events for $m_{H^{\pm }}\lesssim 350\hspace{0.5em}\mathrm{GeV}$ in $500\hspace{0.5em}{\mathrm{fb}}^{-1}$ at a $500\hspace{0.5em}\mathrm{GeV}{e}^{+}{e}^{-}$ collider, or $m_{H^{\pm }}\lesssim 600\hspace{0.5em}\mathrm{GeV}$ in $1000\hspace{0.5em}{\mathrm{fb}}^{-1}$ at a 1000 GeV collider. 80% left-handed polarization of the $e^{-}$ beam improves these reaches to $m_{H^{\pm }}\lesssim 375\hspace{0.5em}\mathrm{GeV}$ and $m_{H^{\pm }}\lesssim 670\hspace{0.5em}\mathrm{GeV},$ respectively.

The polarization of the ${\Lambda }_b$ baryon has been measured in ALEPH, OPAL, and DELPHI experiments. A significant loss on the transfer of the b quark polarization to the ${\Lambda }_b$ baryon polarization has been noticed. This implies that the hadronization effects cannot be neglected. Therefore we may make use of the polarization measurements to look for a suitable model for the ${\Lambda }_b$ distribution function. To investigate the ${\Lambda }_b$ polarization, we construct four models based on a perturbative QCD factorization formula. The models are the quark model, the modified quark model, the parton model, and the modified parton model. The modified models mean the models having transverse degrees of freedom and the associated soft radiative corrections having been resummed. The quark and parton models cannot describe all experiments at the same time. On the other hand, the modified models can have the power to explain all data in the same formalism.

We derive a semiclassical transport equation for fermions propagating in the presence of a $\mathrm{CP}$-violating planar bubble wall at a first order electroweak phase transition. Starting from the Kadanoff-Baym (KB) equation for the two-point (Wightman) function we perform an expansion in gradients, or equivalently in the Planck constant $ħ.$ We show that to first order in $ħ$ the KB equations have a spectral solution, which allows for an on-shell description of the plasma excitations. The $\mathrm{CP}$-violating force acting on these excitations is found to be enhanced by a boost factor in comparison with the (1+1)-dimensional case studied in a former paper. We find that an identical semiclassical force can be obtained by the WKB method. Applications to the MSSM are also mentioned.

We examine the unitarity properties of spontaneously broken noncommutative gauge theories. We find that the symmetry breaking mechanism in the noncommutative standard model of Chaichian et al. leads to an unavoidable violation of tree-level unitarity in gauge boson scattering at high energies. We then study a variety of simplified spontaneously broken noncommutative theories and isolate the source of this unitarity violation. Given the group theoretic restrictions endemic to noncommutative model building, we conclude that it is difficult to build a noncommutative standard model under the Weyl-Moyal approach that preserves unitarity.

This paper explores a new mechanism for B production in which a $\overline{b}$ quark combines with a light parton from the hard-scattering process before hadronizing into the B hadron. This heavy-quark recombination mechanism can be calculated within perturbative QCD up to a few nonperturbative constants. Though suppressed at large transverse momentum by a factor ${\Lambda }_{\mathrm{QCD}}{m}_b{/p}_{\perp }^2$ relative to $\overline{b}$ fragmentation production, it can be important at large rapidities. A signature for this heavy-quark recombination mechanism in $p\overline{p}$ colliders is the presence of rapidity asymmetries in B cross sections. Given reasonable assumptions about the size of nonperturbative parameters entering the calculation, we find that the asymmetries are only significant for rapidities larger than those currently probed by collider experiments.

In scenarios with large extra dimensions and TeV scale gravity, ultrahigh energy neutrinos produce black holes in their interactions with the nucleons. We show that OWL may observe a large number of black hole events and provide valuable information about the fundamental Planck scale and the number of extra dimensions. OWL is especially well suited to observe black hole events produced by neutrinos from the interactions of cosmic rays with the 3 K background radiation. Depending on the parameters of the scenario of large extra dimensions and on the flux model, as many as 28 events per year are expected for a Planck scale of 3 TeV.

We use higher derivative classical gravity to study the nonlinear coupling between the cosmological expansion of the universe and metric oscillations of Planck frequency and very small amplitude. We derive field equations at high orders in the derivative expansion and find that the nature of the new dynamics is extremely restricted. For the equation of state parameter $w>\mathrm{}0\mathrm{}$ the relative importance of the oscillations grows logarithmically. Their effect on the cosmological expansion resembles that of dark energy.

We present a method for the calculation of the gravitational back-reaction cutoff on the smallest scales of cosmic string networks taking into account that not all modes on strings interact with all other modes. This results in a small scale structure cutoff that is sensitive to the initial spectrum of perturbations present on strings. From a simple model, we compute cutoffs in radiation- and matter-dominated universes which are much smaller than the results usually presented in the literature.

We update the branching ratios for the inclusive decays $\overrightarrow{B}{X}_s{l}^{+}{l}^{-}$ and the exclusive decays $\overrightarrow{B}{(K,K}^{*}{)l}^{+}{l}^{-},$ with $l=e,\hspace{0.5em}\mu ,$ in the standard model by including the explicit $O\left({\alpha }_s\right)$ and ${\Lambda }_{\mathrm{QCD}}{/m}_b$ corrections. This framework is used in conjunction with the current measurements of the branching ratios for $\overrightarrow{B}{X}_s\gamma$ and $\overrightarrow{B}{\mathrm{Kl}}^{+}{l}^{-}$ decays and upper limits on the branching ratios for the decays $\overrightarrow{B}{(K}^{*}{,X}_s{)l}^{+}{l}^{-}$ to work out bounds on the Wilson coefficients $C_7,$ $C_8,$ $C_9$ and $C_{10}$ appearing in the effective Hamiltonian formalism. The resulting bounds are found to be consistent with the predictions of the standard model and some variants of supersymmetric theories. We illustrate the constraints on supersymmetric parameters that the current data on rare B decays implies in the context of the minimal flavor violating model and in more general scenarios admitting additional flavor changing mechanisms. Precise measurements of the dilepton invariant mass distributions in the decays $\overrightarrow{B}{(X}_s{,K}^{*}{,K)l}^{+}{l}^{-},$ in particular in the lower dilepton mass region, and the forward-backward asymmetry in the decays $\overrightarrow{B}{(X}_s{,K}^{*}{)l}^{+}{l}^{-},$ will greatly help in discriminating among the SM and various supersymmetric theories.

The main purpose of this paper is to discuss the link between forward-backward multiplicity correlation properties and the shape of the corresponding final charged particle multiplicity distribution in various classes of events in different collisions. It is shown that the same mechanism which explains the shoulder effect and the $H_n$ vs n oscillations in charged particle multiplicity distributions, i.e., the weighted superposition of different classes of events with negative binomial properties, reproduces within experimental errors also the forward-backward multiplicity correlation strength in $e^{+}{e}^{-}$ annihilation at the CERN LEP energy. In addition, it allows interesting predictions for $\mathrm{pp}$ collisions in the TeV energy region, to be tested at the CERN LHC, for instance, with the ALICE detector. We limit ourselves at present to study substructure properties in hadron-hadron collisions and $e^{+}{e}^{-}$ annihilation; they are examined as ancillary examples in the conviction that their understanding might be relevant also in other more complex cases.

We propose that neutrino-proton elastic scattering, $\nu +\overrightarrow{p}\nu +p,$ can be used for the detection of supernova neutrinos in scintillator detectors. Though the proton recoil kinetic energy spectrum is soft, with $T_p\simeq {2E}_{\nu }^2{/M}_p,$ and the scintillation light output from slow, heavily ionizing protons is quenched, the yield above a realistic threshold is nearly as large as that from ${\overline{\nu }}_e+\overrightarrow{p}{e}^{+}+n.\mathrm{}$ In addition, the measured proton spectrum is related to the incident neutrino spectrum, which solves a long-standing problem of how to separately measure the total energy and temperature of ${\nu }_{\mu },$ ${\nu }_{\tau },$ ${\overline{\nu }}_{\mu },$ and ${\overline{\nu }}_{\tau }.$ The ability to detect this signal would give detectors like KamLAND and Borexino a crucial and unique role in the quest to detect supernova neutrinos.

We solve the five dimensional vacuum Einstein equations for several kinds of anisotropic geometries. We consider metrics in which the spatial slices are characterized as Bianchi types II and V, and the scale factors are dependent both on time and a noncompact fifth coordinate. We examine the behavior of the solutions we find, exploring them within the context of the induced matter model.

Phasing formulas in a recent paper of ours’ [Phys. Rev. D 63, 044023 (2001)] are updated taking into account the recent 3.5PN results. Some misprints in our recent paper are also corrected.

We study the bosonic and fermionic zero modes in noncommutative instanton backgrounds based on the Atiyah-Drinfeld-Hitchin-Manin (ADHM) construction. In the k instanton background in $U\left(N\right)\mathrm{}$ gauge theory, we show how to explicitly construct $4Nk$ $\mathrm{}\left(2Nk\right)\mathrm{}$ bosonic (fermionic) zero modes in the adjoint representation and $2k$ $\mathrm{}\left(k\right)\mathrm{}$ bosonic (fermionic) zero modes in the fundamental representation from the ADHM construction. The number of fermionic zero modes is also shown to be exactly equal to the Atiyah-Singer index of the Dirac operator in the noncommutative instanton background. We point out that (super)conformal zero modes in non-Bogomol’nyi-Prasad-Sommerfield instantons are affected by the noncommutativity. The role of Lorentz symmetry breaking by the noncommutativity is also briefly discussed to figure out the structure of $U\left(1\right)\mathrm{}$ instantons.

We study in detail the quantum field theory of mixing among three generations of Dirac fermions (neutrinos). We construct the Hilbert space for the flavor fields and determine the generators of the mixing transformations. By use of these generators, we recover all the known parametrizations of the three flavor mixing matrix and we find a number of new ones. The algebra of the currents associated with the mixing transformations is shown to be a deformed $\mathrm{su}\left(3\right)\mathrm{}$ algebra, when $\mathrm{CP}$ violating phases are present. We then derive the exact oscillation formulas, exhibiting new features with respect to the usual ones. $\mathrm{CP}$ and T violation are also discussed.

We consider the application of the Aichelburg-Sexl boost to plane and line distributions of matter. Our analysis shows that for a domain wall the space-time after the boost is flat except on a null hypersurface which is the history of a null shell. For a cosmic string we study the influence of the boost on the conical singularity and give the new value of the conical deficit.

In this paper we review how to construct scalar field theories in two-dimensional space-time that support kink or bouncelike solutions starting from solvable Schrödinger equations. Three different Schrödinger potentials are analyzed. We obtain two new models starting from the Morse and Scarf II hyperbolic potentials, i.e. the $U\left(\phi \right)={\phi }^2{\ln }^2\left({\phi }^2\right)$ and $U\left(\phi \right)={\phi }^2{\cos }^2\ln \left({\phi }^2\right)$ models, respectively. Also we give a closed expression for the (renormalized) kink quantum mass corrections in the case of the second model and evaluate it numerically.

We study different renormalization group flows for scale-dependent effective actions, including exact and proper-time renormalization group flows. These flows have a simple one-loop structure. They differ in their dependence on the full field-dependent propagator, which is linear for exact flows. We investigate the inherent approximations of flows with a nonlinear dependence on the propagator. We check explicitly that standard perturbation theory is not reproduced. We explain the origin of the discrepancy by providing links to exact flows both in closed expressions and in given approximations. We show that proper-time flows are approximations to Callan-Symanzik flows. Within a background field formalism, we provide a generalized proper-time flow, which is exact. Implications of these findings are discussed.

We study three-dimensional quenched quantum electrodynamics in the bare vertex approximation. We investigate the gauge dependence of the dynamically generated Euclidean mass of the fermion and the chiral condensate for a wide range of values of the covariant gauge parameter $\xi .$ We find that (i) away from the Landau gauge toward large positive values of $\xi ,$ the gauge dependence of the said quantities is considerably reduced without resorting to sophisticated vertex Ansätze, (ii) wave function renormalization plays an important role in restoring gauge invariance, and (iii) the Ward-Green-Takahashi identity seems to increase the gauge dependence when used in conjunction with some simplifying assumptions. In the Landau gauge, we also verify that our results are in agreement with those based upon the dimensional regularization scheme within the numerical accuracy available.

We investigate the symmetry properties for Baym’s $\Phi$-derivable schemes. We show that in general the solutions of the dynamical equations of motion, derived from approximations of the $\Phi$ functional, do not satisfy the Ward-Takahashi identities of the symmetry of the underlying classical action, although the conservation laws for the expectation values of the corresponding Noether currents are satisfied exactly for the approximation. Further we prove that one can define an effective action functional in terms of the self-consistent propagators which is invariant under the operation of the same symmetry group representation as the classical action. The requirements for this theorem to hold true are the same as for perturbative approximations: The symmetry has to be realized linearly on the fields and it must be free of anomalies; i.e., there should exist a symmetry-conserving regularization scheme. In addition, if the theory is renormalizable in Dyson’s narrow sense, it can be renormalized with counterterms which do not violate the symmetry.