It is possible to eliminate exactly all the auxiliary fields (einbein fields) appearing in the rotating string Hamiltonian to obtain the classical equations of motion of the relativistic flux tube model. A clear interpretation can then be done for the characteristic variables of the rotating string model.

The Higgs potential of the minimal nonminimal supersymmetric standard model (MNMSSM) is investigated within the context of electroweak phase transition. We investigate the allowed parameter space yielding correct electroweak phase transitoin employing a high temperature approximation. We devote to phenomenological consequences for the Higgs sector of the MNMSSM for electron-positron colliders. It is observed that a future $e^{+}{e}^{-}$ linear collider with $\sqrt{s}=1000\mathrm{G}\mathrm{e}\mathrm{V}$ will be able to test the model with regard to electroweak baryogenesis.

Unfreezing the radial degree of freedom, we study the three-dimensional Abelian Higgs model with compact gauge field and fundamentally charged matter. For small quartic Higgs self coupling and finite gauge coupling the model possesses a first order transition from the confined/symmetric phase to the deconfined/Higgs phase separated at some hopping parameter ${\kappa }_c$. At larger quartic coupling the first order transition ceases to exist, and the behavior becomes similar to that known from the London limit. These observations are complemented by a study of the photon propagator in Landau gauge in the two different regimes. The problems afflicting the gauge fixing procedure are carefully investigated. We propose an improved gauge fixing algorithm which uses a finite subgroup in a preselection/preconditioning stage. As far as the gauge boson propagator is concerned, we find that the radially active Higgs field provides qualitatively no new effect compared to the radially frozen Higgs field studied before.

Starting with a hidden local symmetry Lagrangian at the vector manifestation (VM) fixed point that incorporates heavy-quark symmetry and matching the bare theory to QCD, we calculate the splitting of chiral doublers of heavy-light mesons proposed by Nowak, Rho, and Zahed [M. A. Nowak, M. Rho, and I. Zahed, Phys. Rev. D 48, 4370 (1993).] and Bardeen and Hill [W. A. Bardeen and C. T. Hill, Phys. Rev. D 49, 409 (1994).]. We show, in the three-flavor chiral limit, that the splitting is directly proportional to the light-quark condensate $\langle \overline{q}q\rangle$ and comes out to be $\sim \frac{1}{3}{m}_N$ where $m_N$ is the nucleon mass, implying that the splitting vanishes in the chiral limit at the chiral restoration point—temperature $T_c$, density $n_c$, or number of flavors $N_f^c$. The result turns out to be surprisingly simple with the vector ($\rho$) meson playing the crucial role in quantum corrections, pointing to the relevance of the VM to QCD in the way chiral symmetry is manifested in hadronic matter. We also make predictions on the hadronic decay processes of the excited heavy- (charm) light mesons $\tilde{D}$.

We present a new numerical method for the construction of quasiequilibrium models of black hole-neutron star binaries. We solve the constraint equations of general relativity, decomposed in the conformal thin-sandwich formalism, together with the Euler equation for the neutron star matter. We take the system to be stationary in a corotating frame and thereby assume the presence of a helical Killing vector. We solve these coupled equations in the background metric of a Kerr-Schild black hole, which accounts for the neutron star’s black hole companion. In this paper we adopt a polytropic equation of state for the neutron star matter and assume large black hole-to-neutron star mass ratios. These simplifications allow us to focus on the construction of quasiequilibrium neutron star models in the presence of strong-field, black hole companions. We summarize the results of several code tests, compare with Newtonian models, and locate the onset of tidal disruption in a fully relativistic framework.

We show that a self-tuning mechanism of the cosmological constant could work in 5D noncompact space-time with a $Z_2$ symmetry in the presence of a massless scalar field. The standard model matter fields live only on the 4D brane. The change of vacuum energy on the brane (brane cosmological constant) by, for instance, electroweak and QCD phase transitions, just gives rise to dynamical shifts of the profiles of the background metric and the scalar field in the extra dimension, keeping 4D space-time flat without any fine-tuning. To avoid naked singularities in the bulk, the brane cosmological constant should be negative. We introduce an additional brane-localized 4D Einstein-Hilbert term so as to provide the observed 4D gravity with the noncompact extra dimension. With a general form of the brane-localized gravity term allowed by the symmetries, the low energy Einstein gravity is successfully reproduced on the brane at long distances. We show this phenomenon explicitly for the case of vanishing bulk cosmological constant.

We present two families of solutions $(g,\Phi )$ of the Einstein-Klein-Gordon system minimally coupled to gravity, massless scalar field equations possessing a regular $\mathbb{R}\times S^2$ bifurcating Killing horizon. The solutions may be interpreted as describing the metric $g$ and the field $\Phi$ in an open vicinity containing the event horizon of a Schwarzschild black hole interacting with an exterior, static-axisymmetric distribution of matter carrying scalar charges generating $\Phi$. One family of the solution possesses a spherical bifurcation two sphere and may be interpreted as generated by a distribution of matter carrying scalar charges but of negligible self-gravity. The other family describes an axisymmetric horizon with the distortion caused by the self-gravity of the external matter. For both classes of solutions the scalar field $\Phi$ relaxes into a configuration so that its energy-momentum tensor $T^{\mu \nu }$ on the Killing horizon obeys the property: $T^{\mu \nu }{l}_{\mu }{l}_{\nu }=0$ where $l^{\mu }$ is a null vector normal to the horizon. It is also indicated that the Einstein-Klein-Gordon system ought to admit distorted black holes characterized by an $\mathbb{R}\times S^1\times S^1$ event horizon.

We compute power-suppressed corrections to the $\eta \gamma$ and ${\eta }^{\prime }\gamma$ transition form factors $Q^2{F}_{\eta ({\eta }^{\prime })\gamma }(Q^2)$ arising from the end point regions $x\to 0,1$ by employing the infrared-renormalon approach. The contribution to the form factors from the quark and gluon content of the $\eta ,{\eta }^{\prime }$ mesons is taken into account using for the $\eta -{\eta }^{\prime }$ mixing the ${\mathrm{S}\mathrm{U}}_f(3)$ singlet ${\eta }_1$ and octet ${\eta }_8$ basis. The theoretical predictions obtained this way are compared with the corresponding CLEO data and restrictions on the input parameters (Gegenbauer coefficients) $B_2^q({\eta }_1)$, $B_2^g({\eta }_1)$, and $B_2^q({\eta }_8)$ in the distribution amplitudes for the ${\eta }_1,{\eta }_8$ states with one nonasymptotic term are deduced. Comparison is made with the results from QCD perturbation theory.

We consider a model for the reionization history of the Universe in which a significant fraction of the observed optical depth is a result of direct reionization by the decay products of a scaling cosmic defect network. We show that such network can make a significant contribution to the reionization history of the Universe even if its energy density is very small (the defect energy density has to be greater than about ${10}^{-11}$ of the background density). We compute the Cosmic Microwave Background temperature, polarization and temperature-polarization cross power spectrum and show that a contribution to the observed optical depth due to the decay products of a scaling defect network may help to reconcile a high optical depth with a low redshift of complete reionization suggested by quasar data. However, if the energy density of defects is approximately a constant fraction of the background density then these models do not explain the large scale bump in the temperature-polarization cross power spectrum observed by Wilkinson Microwave Anisotropy Probe.

We extend the Veneziano-Yankielowicz (VY) effective theory in order to account for ordinary glueball states. We propose a new form of the superpotential including a chiral superfield for the glueball degrees of freedom. When integrating it out we obtain the VY superpotential while the N vacua of the theory naturally emerge. This fact has a counterpart in the Dijkgraaf and Vafa geometric approach. We suggest a link of the new field with the underlying degrees of freedom which allows us to integrate it in the VY theory. We finally break supersymmetry by adding a gluino mass and show that the Kähler independent part of the potential has the same form of the ordinary Yang-Mills glueball effective potential.

We point out that double distributions need not vanish at their boundary. Boundary terms do not change the ambiguity inherent in defining double distributions; instead, boundary conditions must be satisfied in order to switch between different decompositions. We analyze both the spin zero and spin one-half cases.

This paper is an investigation of the pion form factor utilizing recently developed effective field theory techniques. The primary results reported are both the transition and electromagnetic form factors are corrected at order $\Lambda /Q$ due to time ordered products which account for deviations of the pion from being a state composed purely of highly energetic collinear quarks in the lab frame. The usual higher twist wave function corrections contribute only at order ${\Lambda }^2/Q^2$, when the quark mass vanishes. In the case of the electromagnetic form factor the $\Lambda /Q$ power correction is enhanced by a power of $1/{\alpha }_s(Q)$ relative to the leading order result of Brodsky and Lepage, if the scale $\sqrt{\Lambda Q}$ is nonperturbative. This enhanced correction could explain the discrepancy with the data.

Here we study the effect of the nonminimal coupling $j^{\mu }{ϵ}_{\mu \nu \alpha }{\partial }^{\nu }{A}^{\alpha }$ on the static potential in multiflavor ${\mathrm{Q}\mathrm{E}\mathrm{D}}_3$. Both cases of four and two components fermions are studied separately at leading order in the $1/N$ expansion. Although a nonlocal Chern-Simons term appears, in the four components case the photon is still massless leading to a confining logarithmic potential similar to the classical one. In the two components case, as expected, the parity breaking fermion mass term generates a traditional Chern-Simons term which makes the photon massive and we have a screening potential which vanishes at large intercharge distance. The extra nonminimal couplings have no important influence on the static potential at large intercharge distances. However, interesting effects show up at finite distances. In particular, for strong enough nonminimal coupling we may have a new massive pole in the photon propagator, while in the opposite limit there may be no poles at all in the irreducible case. We also found that, in general, the nonminimal couplings lead to a finite range repulsive force between charges of opposite signs.

Starting from rotational invariance we derive sum rules for the single-spin asymmetries in inclusive production and binary processes. We also get sum rules for spin correlation parameters in elastic $pp$-scattering.

Recent studies of exclusive electroproduction of vector mesons at JLab make it possible for the first time to play with two independent hard scales: the virtuality $Q^2$ of the photon, which sets the observation scale, and the momentum transfer $t$ to the hadronic system, which sets the interaction scale. They reinforce the description of hard-scattering processes in terms of few effective degrees of freedom relevant to the JLab-Hermes energy range.

We discuss experimental and observational constraints on certain models of higher dimensional light Majorana neutrinos. Models with flavor blind brane-bulk couplings plus three or four flavor diagonal light Majorana neutrinos on the brane, with subsequent mixing induced solely by the Kaluza-Klein tower of states, are found to be excluded by data on the oscillations of solar, atmospheric and reactor neutrinos, taken together with the cosmological upper bound on the sum of neutrino masses. Extra dimensions, if relevant to neutrino mixing, need to discriminate between neutrino flavors.

We investigate the elastic form factors of the $\rho$ meson in the light-front quark model (LFQM). With the phenomenologically accessible meson vertices including the one obtained by the Melosh transformation frequently used in the LFQM, we find that only the helicity $0\to 0$ matrix element of the plus current receives the zero-mode contribution. We quantify the zero-mode contribution in the helicity $0\to 0$ amplitude using the angular condition of spin-1 system. After taking care of the zero-mode issue, we obtain the magnetic ($\mu$) and quadrupole ($Q$) moments of the $\rho$ meson as $\mu =1.92$ and $Q=0.43$, respectively, in the LFQM consistent with the Melosh transformation and compare our results with other available theoretical predictions.

A generalized Tomonaga-Schwinger equation, holding on the entire boundary of a finite spacetime region, has recently been considered as a tool for studying particle scattering amplitudes in background-independent quantum field theory. The equation has been derived using lattice techniques under assumptions on the existence of the continuum limit. Here I show that in the context of continuous Euclidean field theory the equation can be directly derived from the functional integral formalism, using a technique based on Hadamard’s formula for the variation of the propagator.