Letter: Fluids of Vortices and Dark Matter

By considering full-field string solutions of the Abelian–Higgs model, we modify the model of a fluid of strings (which is composed of Nambu strings) to obtain a model for a fluid of vortices. With this model, and following closely Soleng's proposal of a fluid of strings as the source of a Milgrom-type correction to the Newton dynamics, we determine quantitatively the modified dynamics generated by a static, spherical fluid of vortices.     

Cosmic strings in a space–time with positive cosmological constant

We study Abelian strings in a fixed de Sitter background. We find that the gauge and Higgs fields extend smoothly across the cosmological horizon and that the string solutions have oscillating scalar fields outside the cosmological horizon for all currently accepted values of the cosmological constant. If the gauge to Higgs boson mass ratio is small enough, the gauge field function has a power-like behaviour, while it is oscillating outside the cosmological horizon if Higgs and gauge boson mass are comparable. Moreover, we observe that Abelian strings exist only up to a maximal value of the cosmological constant and that two branches of solutions exist that meet at this maximal value. We also construct radially excited solutions that only exist for non-vanishing values of the cosmological constant and are thus a novel feature as compared to flat space–time. Considering the effect of the de Sitter string on the space–time, we observe that the deficit angle increases with increasing cosmological constant. Lensed objects would thus be separated by a larger angle as compared to asymptotically flat space–time.     

Inflation and cosmic strings in models with dynamical symmetry breaking

We derive the effective action for the composite field which in dynamical symmetry breaking plays the role of the Higgs field. We show that this effective action does not give rise to inflation. It is, however, possible to obtain topological defects such as cosmic strings. There will be fermionic zero modes trapped on the strings, and the strings will therefore be superconducting in a generalized sense.     

Finite tension strings in SU(2) gauge theory

The second-order field equations of the SU(2) Higgs model are studied and a new class of string solutions is obtained. The tension is finite and scale-dependent and the strings are of minus one unit flux.     

Fermionic string from Abelian Higgs model with monopoles and Θ-term

The four-dimensional Abelian Higgs model with monopoles and Θ-term is considered in the limit of large mass of the Higgs boson. We show that for Θ=2π the theory is equivalent, at large distances, to summation over all possible world-sheets of fermionic strings with Dirichlet-type boundary conditions on the string coordinates. Pis’ma Zh. éksp. Teor. Fiz. 64, No. 2, 76–80 (25 July 1996) Published in English in the original Russian journal. Edited by Steve Torstveit.     

Search strategies for non-standard Higgs bosons at future ee colliders

Already in the simplest two-Higgs-doublet model with CP violation in the Higgs sector, the 3×3 mixing matrix for the neutral Higgs bosons can substantially modify their couplings, thereby endangering the “classical” Higgs search strategies. However, there are sum rules relating Yukawa and Higgs–Z couplings which ensure that the ZZ, and couplings of a given neutral 2HDM Higgs boson cannot all be simultaneously suppressed. This result implies that any single Higgs boson will be detectable at an e⁺e⁻ collider if the Z+Higgs, Higgs and Higgs production channels are all kinematically accessible and if the integrated luminosity is sufficient. We explore, as a function of Higgs mass, the luminosity required to guarantee Higgs boson detection, and find that for moderate tanβ values the needed luminosity is unlikely to be available for all possible mixing scenarios. Implications of the sum rules for Higgs discovery at the Tevatron and LHC are briefly discussed.     

Grand unification and B&L conservation

A brief summary of some of the recent developments in grand unification and B&;L conservation is given. Proton stability in supergravity unified models is discussed. Also discussed are the effects of supersymmetric dark matter constraints and the constraints of proton lifetime on the SUSY spectrum. Other topics reviewed include Planck scale effects and p decay, effects of textures, and extension to nonminimal models including models with many Higgs triplets. Recent developments in GUTs and strings are also discussed.     

Superconducting strings

It is known that certain spontaneously broken gauge theories give rise to stable strings or vortex lines. In this paper it is shown that under certain conditions such strings behave like superconducting wires whose passage through astrophysical magnetic fields would generate a variety of striking and perhaps observable effects. The superconducting charge carriers may be either bosons (if a charged Higgs field has an expectation value in the core of the string) or fermions (if charged fermions are trapped in zero modes along the string, as is known to occur in certain circumstances). They might be observable as synchrotron sources or as sources of high-energy cosmic rays. If the charge carriers are ordinary quarks and leptons, the strings have important baryon number violating interactions with magnetic fields; such a string, traversing a galactic magnetic field of 10^?6 G, creates baryons (or antibaryons) at a rate of order 10¹² particles/cm of string per second.     

Dynamical interactions of cosmic strings and flux vortices in superconductors

We perform a numerical simulation of the dynamical interactions of vortex excitations in the abelian Higgs model. These structures can be interpreted as cross sections of cosmic strings or of magnetic flux tubes trapped in a superconductor. Although at a critical value of the coupling constant the interaction energy between static vortices vanishes, colliding vortices interact nontrivially by scattering at 90° in a head-on collision, and are therefore not solitons. We also observe 90° scattering at non-critical values of the coupling constant.     

Stable charged cosmic strings

We study the quantum stabilization of a cosmic string by a heavy fermion doublet in a reduced version of the standard model. We show that charged strings, obtained by populating fermionic bound state levels, become stable if the electroweak bosons are coupled to a fermion that is less than twice as heavy as the top quark. This result suggests that extraordinarily large fermion masses or unrealistic couplings are not required to bind a cosmic string in the standard model. Numerically we find the most favorable string profile to be a simple trough in the Higgs vacuum expectation value of radius ≈10(-18) m. The vacuum remains stable in our model, because neutral strings are not energetically favored.     

The effect of the location of the new Higgs doublet on the radiative lepton flavor violating decays in the split fermion scenario

We study the branching ratios of the lepton flavor violating processes μ→eγ, τ→eγ and τ→μγ in the split fermion scenario, with the assumption that the new Higgs doublet is restricted to the 4D brane (thin bulk) in one and two extra dimensions, in the framework of the two Higgs doublet model. We observe that the branching ratios are sensitive to the location of the 4D brane and, in the second case, the width of the thin bulk, especially for the μ→eγ decay.     

Searching for light Higgs scalar bosons in the next generation of electron-positron collider at LEP

Thee ⁺ e ^–-collider facilities at LEP II, with the CM energy S in the range 100–170 GeV, may be able to detect light Higgs bosons, assuming a high luminosity. The production cross sections of a light Higgs bosonH ⁰ in association with the neutral gauge bosonZ ⁰ are calculated for varying ranges of the CM energy expected to be available to LEP II and VLEEP (Novosibirsk) and for various values of the light Higgs mass. It is found that production cross sections are sizable in comparison with those for the very massive Higgs bosons in proton-anti(proton) supercolliders, Tevatron, Sp¯pS, and SSC, respectively. The implication of this feature is pointed out. Further, prospects for light Higgs production in association with the charged gauge bosonW ^– in ultraenergetic neutrino beams are examined.     

The bose form of two-dimensional quantum chromodynamics

By means of a special choice of gauge QCD₂ [SU(N)] with one flavor of quarks is recast into the Bose form. Weak (g m) and strong (gm) coupling regimes are studied. The former is shown to be the SU(N)-symmetric confining phase in which bound states possess stringlike configurations with strings being represented by electric vortex lines; the ordinary mesons and baryons appear as longitudinal modes of electric strings. The strong coupling regime describes the Higgs phase with the residual symmetry [U(1)]^N−1 S_N where the left and right factors are the maximal abelian subgroup of SU(N) and the permutation group of N quarks, respectively; the particle spectrum consists of S_N multiplets and the [Uw(1)]^N−1 charges are trapped.     

Electroweak corrections to the fermionic decay width of the standard Higgs boson

The partial decay width of the standard model Higgs particle into a general species of fermions is given at the electroweak 1-loop level. The analytic formulae are applicable to light and heavy fermions. Numerical results are presented for Higgs decays intob andt quarks and into charged leptons. For not too heavy Higgs bosons the radiative corrections are of the order of a few per cent. In particular for Higgs bosons below theW ⁺ W ^– threshold the correction to the partial width intob quarks is very small and insensitive to the top mass. For every heavy Higgs bosons the 1-loop corrections increase the fermionic decay widths for all channels up to 15%.     

Signatures of extra dimensions from upsilon decays with a light gaugephobic Higgs boson

We explore non-standard Higgs phenomenology in the gaugephobic Higgs model in which the Higgs can be lighter than the usually quoted current experimental bound. The Higgs propagates in the bulk of a 5D space–time and Electroweak Symmetry Breaking occurs by a combination of boundary conditions in the extra dimension and an elementary Higgs. The Higgs can thus have a significantly suppressed coupling to the other Standard Model fields. A large enough suppression can be found to escape all limits and allow for a Higgs of any mass, which would be associated with the discovery of W^′ and Z^′ Kaluza–Klein resonances at the LHC. The Higgs can be precisely discovered at B-factories while the LHC would be insensitive to it due to high backgrounds. In this Letter we study the Higgs discovery mode in (3S), (2S), and (1S) decays, and the model parameter space that will be probed by BaBar, Belle, and CLEO data. In the absence of an early discovery of a heavy Higgs at the LHC, A Super-B factory would be an excellent option to further probe this region.     

Standard-like models from intersecting D4-branes

We construct a one-parameter set of intersecting D4-brane models, with six stacks, that yield the (non-supersymmetric) standard model plus extra vector-like matter. Twisted tadpoles and gauge anomalies are cancelled, and the model contains all of the Yukawa couplings to the tachyonic Higgs doublets that are needed to generate mass terms for the fermions. A string scale in the range 1–10 TeV and a Higgs mass not much greater than the current bound is obtained for certain values of the parameters, consistently with the observed values of the gauge coupling constants.     

Superconducting cosmic strings. II. Spacetime curvature

We solve the Einstein-Maxwell and scalar field equations for an infinitely long bosonic superconducting cosmic string and explore the associated geometry of space-time. The metric describing the space-time is valid for both fermionic and bosonic superconducting cosmic strings. Due to general relativistic corrections, the magnetic field energy per unit length associated with the string does not diverge. A non-uniform charged Higgs field contribution to the stress-energy tensor endows the string with an effective mass that enables to attract gravitationally and alters its lensing properties.     

Search for Higgs Boson in UHE Cosmic Rays

Considering the SM Higgs boson mass in the range of (95–235) GeV, we present here a mechanism for indirect searches of this scalar in UHE cosmic rays interactions. The mechanism is the decay of Higgs bosons which are produced through bubble formation due to vacuum excitation in an UHE cosmic rays interactions with air nuclei. We develop a model of hadronic interaction based on algorithms of the GENCL code of the UA5 experiment of CERN and some physics of CORSIKA code (Karlsruhe report), incorporating a fraction of energy transfer to bubble formation through vacuum excitation and subsequent multiparticle production via conversion of Higgs boson to heavy fermion pairs. Such events are expected to have high multiplicity and excess muons. This mechanism has significant effect starting from E _P 10¹⁸eV. It is found that the average muon number decreases gradually upto 175 GeV Higgs boson mass and remain practically constant thereafter for all primary energies (E _P) above 10¹⁸ eV and for all fractions of energy transfer (f _e 0.01–0.5). The fluctuation of muon multiplicity decreases with E _P and increases very slowly with Higgs mass upto 175 GeV, remaining practically invariant thereafter.     

On the equivalence of the Lagrangians of massless dirac and supersymmetrical particles

The classical equivalence between the Lagrangians of massless spinning and supersymmetrical particles presented in terms of u _A and Grassmannian _A Weyl spinor variables is established. It is shown that the condition of the inverse Higgs effect for a spinor invariant superform leads to the extension of the Penrose representation and the realization of fermionic string variables in terms of superstring variables. New superfield formulations of the actions for particles and strings invariant under local (world-sheet) and global (spacetime) supersymmetrics are suggested.     

Topological Solutions in the Self-dual Chern–Simons–Higgs Theory in a Background Metric

In this Letter we show the existence of topological multi-vortex solutions in the self-dual Chern–Simons–Higgs theory in a background metric which interpolates flat spacetime and cylinder smoothly.