Monopole Mass Research Articles

Gravitational scattering on a global monopole.

The scattering amplitude and the total scattering cross section of massless particles propagating in the gravitational field of a global monopole are derived. We find that the physical signature of such defects is a ringlike angular region where the scattering amplitude is very large. The size of this ringlike region is determined by the ratio of the global monopole mass to the Planck mass and its appearance stems from the fact that the metric of the global monopole is not asymptotically flat but rather displays the characteristic spherical angle defect. The situation is therefore very much reminiscent of scattering in the gravitational field of the cosmic string.

Monopole condensate and monopole mass in U(1) lattice gauge theory

The monopole condensate in the confined phase and the monopole mass in the Coulomb phase of U(1) lattice gauge theory are computed in numerical simulations using a monopole correlation function introduced by Fröhlich and Marchetti. The finite-size effects of (magnetically) charged particles in periodic and antiperiodic volumes are discussed in detail and their relation to the infraparticle problem is investigated. By duality the results also apply to the noncompact abelian Higgs model.

Mass limit for Dirac-type magnetic monopoles

We calculate the contribution of virtual monopole-antimonopole pairs to the anomalous magnetic moment of the muon ( g−2) μ . If strong coupling QED generates confinement of monopole-antimonopole pairs, as suggested by recent lattice calculations, most of the monopole search experiments would not have been capable of detecting monopoles. However, such confined systems contribute to radiative corrections. We conclude that the effective monopole mass has to be larger than 120 GeV.

Magnetic monopoles and superconducting cosmic strings

This letter shows that a superconducting cosmic string is an extremely efficient producer of magnetic monopoles if the mass of the magnetic monopole is of the same order of magnitude as the symmetry breaking mass that generates the string. Given the absence of any observed monopoles, this calculation casts severe doubt on the existence of superconducting cosmic strings. If such strings do exist, a superconducting string may have en effective maximal current several orders of magnitude below the standard theoretically predicted limit.

Monopole in the Coleman-Weinberg model

The quantized 't Hooft-Polyakov monopole is investigated at small mass μ of the scalar field when symmetry breaking is due to the Coleman-Weinberg mechanism. The BPS limit is unachievable because of monopole instability. The stability threshold and logarithmically large terms in quantum correction to the monopole mass are obtained.

Are massive photons and monopoles mutually exclusive?

Linear equations, constructed from quantities transforming according to the same representations of the Lorentz group as those making up Maxwell's equations, are used to investigate the effect of a photon mass on the existence of monopoles. For stable point particlesand one kind of photon it is shown that isolated monopoles cannot exist. Dirac strings are employed in the proof.

MONOPOLE ACCRETION BY COSMIC STRINGS

We study the accretion of super-heavy magnetic monopoles around cosmic string loops in the very early universe. For sufficiently massive monopoles, a possible result of this accretion process is the formation of monopole-black holes, leading ultimately to a monopole-to-photon ratio comparable to the limits required by neutron star observations.

Generalized maxwell equations and quantum mechanics. I. Dirac equation for the free electron

Some preliminary results presented in two previous papers are expanded upon. In the first it was shown that the Maxwell equations are equivalent to a nonlinear Dirac-like spinor equation. In the present paper it is shown that, in that formalism, the Dirac equation for the free electron is susceptible to a puzzling reinterpretation. In fact, it is shown that the Dirac equation is equivalent to the Maxwell equations for an electromagnetic field generated by two currents: one electric in nature and one, magnetic-monopolar. The elaboration of this result brings a nonlinear generalization of Maxwell's equations, as well as a nonlinear Dirac-like equation fully equivalent to them, from which both the electron mass as well as the magnetic monopole mass appear to be fully electromagnetic in nature, and the magnetic monopole to be tachyonic. The corresponding nonlinear Dirac equation reduces, under suitable approximations, to the ordinary Dirac equation for the free electron.

Gravitational particle production in the formation of global monopoles

The changing spacetime metric associated with the formation of global monopoles in the early universe will create particles. The total energy in created particles is estimated; it will exceed the energy in monopoles (and hence may be dynamically important) if the monopole mass exceeds roughly 7×10 17GeV.

Quantum correction to the monopole mass

For a quantum correction to the 't Hooft-Polyakov monopole mass the terms which are singular in the BPS limit are considered.

LVD at Gran Sasso

LVD is a large volume detector which will be installed in Hall A of the Gran Sasso Laboratory. This detector is 49 m long, 13.2 m high and 12 m wide. It contains 2280 m 3 of scintillator (1800 t) and 1800 t of steel. The geometric acceptance of LVD for an isotropic flux of particles is greater than 7000 m 2 sr. LVD is the ideal detector for detecting a stellar collapse, anywhere in our galaxy; for studying neutrino oscillations; for searching for the supersymmetric decay mode of the proton; and for looking at the boron neutrinos from the sun. LVD is a very competitive detector for detecting astrophysical neutrino emitting point sources, for performing dark matter searches, for studying single muon distributions, for detecting muon bundles and hence determining the primary cosmic ray composition, and for searching for massive monopoles and other ultra heavy particles. LVD is composed of 190 identical modules, of which the first 10% of these modules will installed in 1987.

Search for magnetic monopoles trapped in old iron ores using a superconducting detector.

Magnetically trapped monopoles were sought in iron ores using a set of two SQUID (superconducting quantum-interference device) fluxmeters. We operated the apparatus under a sintering furnace in an industrial ore-processing plant for two months and tried to observe a signal of a monopole penetrating superconducting coils after its release from ore paramagnetized through a heat treatment. No candidate events were found consistent with the passage of a magnetic charge greater than 0.6 times Dirac's unit strength g/sub D/. The total weight of ore examined varies between 137 and approx.10/sup 4/ tons, depending on what mechanism is assumed for the release of monopoles. By taking the most modest estimate, we obtain an upper limit of 2.2 x 10/sup -7/ monopoles/g (95% confidence level (C.L.)) for the density of very massive monopoles (10/sup 14/--10/sup 17/ GeV/c/sup 2/) in iron ores which involve ferro/ferri-ferrimagnetic ingredients of age 10/sup 7/--10/sup 9/ yr to the extent of 10%. The free-monopole flux is also obtained as less than 1.4 x 10/sup -10//cm/sup 2/sec sr (90% C.L.), irrespective of its mass or velocity from a 57-d live time of two 20-cm-diam search coils.

Charge neutrality of atoms and magnetic monopoles.

Under the assumption that charge conservation and charge quan- tization are exact, it is pointed out that the expectation values f the charges can still deviate from the exact quantized eigenvalues, as long as the charge superselection rule is not absolute. The deviations can be suppressed by a large energy scale, identified as the mass of the magnetic monopole. Existing experimental results are consistent with \ensuremath{\Delta}${Q}_{p}$+\ensuremath{\Delta}${Q}_{e}$\ensuremath{\approxeq}3\ifmmode\times\else\texttimes\fi{}${10}^{\mathrm{\ensuremath{-}}20}$e and \ensuremath{\Delta}${Q}_{n}$\ensuremath{\approxeq}-3\ifmmode\times\else\texttimes\fi{}${10}^{\mathrm{\ensuremath{-}}20}$e, where \ensuremath{\Delta}${Q}_{i}$ is the deviation for particle i. Implications, in particular \ensuremath{\approxeq}6\ifmmode\times\else\texttimes\fi{}${10}^{\mathrm{\ensuremath{-}}20}$e, are discussed.

Any physical, monopole equation of motion structure uniquely determines a projective inertial structure and an (n−1)-force

It is proved that, in the context of a conformal causal structure, (a) any acceleration field decomposes uniquely into the sum of an affine structure that is compatible with the conformal structure and an n-force, and (b) any directing field, such that the n-force of the corresponding family of acceleration fields is due to tensor fields and is orthogonal to the n-velocity, uniquely decomposes into a projective structure that is compatible with the conformal structure and an (n−1)-force. Moreover, if there are no second clock effects and variable rest masses do not exist, there exists a unique pseudo-Riemannian metric on space-time that determines the unique standard of no acceleration for all massive monopoles. It follows from this that a non-null result for the Eötvös experiment entails the existence of a fifth force rather than a violation of the universality of free fall.

On energy in 5-dimensional gravity and the mass of the Kaluza-Klein monopole

We discuss the concept of energy in higher-dimensional gravity, with special attention given to the problem of the choice of a background. Three different approaches to the calculation of energy for solutions of the 5-dimensional Einstein equation are considered. They are then shown to be equivalent and applied to the calculation of the mass of the Kaluza-Klein monopole. The question of the reduction of a 5-dimensional theory to an effective 4-dimensional one in the presence of a Killing vector field along the compact dimension is then discussed, in particular with regard to the conformal ambiguity in the definition of the metric in the reduced theory. We show that there exists an essentially unique choice of reduction for which the 4-dimensional energy has the usual general relativistic form, and that for the Kaluza-Klein monopole this is the reduction that will make the “naive” 4-dimensional energy additive.

Particle physicists’ candidates for dark matter

A review is presented of the candidates for dark matter that arise in different particle theories. These include massive neutrinos and monopoles in grand unified theories, axions arising from attempts to explain cp conservation in the strong interactions, stable supersymmetric particles such as photinos, gravitinos or sneutrinos, and other possible stable relics from the Big Bang. Wherever possible, relations to laboratory information and possible experiments directly sensitive to the different dark-matter candidates are discussed.

Magnetic monopole detector with sensitivity to extremely small magnetic charge

A magnetic monopole detector with a sensitivity range down to extremely small magnetic charge is described. Backgrounds in the detector are discussed and representative background distributions are given. Appropriate steps to minimize these backgrounds are detailed. The region of sensitivity of the detector to magnetic monopoles in terms of monopole charge and monopole mass is given.

Dirac magnetic-monopole pair production in relativistic nucleus-nucleus collisions

Dirac magnetic-monopole pair production is examined for very-high-energy nucleus-nucleus collisions. Comparisons are made, for various masses of the magnetic monopole, between the rate at which pairs are produced via the Drell-Yan mechanism and from thermalized quark-gluon matter. To do this the fireball model is used. It is pointed out that properties of the quark-gluon plasma can be determined by an accurate specification of the monopole mass. Specifically, lower limits on the energy density of the quark-gluon plasma as well as its temperature can be determined in this way in the kinematical regions where experiment will be able to verify the thermal production of magnetic-monopole pairs. It is pointed out that very-high-multiplicity gamma-ray events are a possible signature of monopole-antimonopole annihilation and a Monte Carlo simulation of this process is performed for various masses of the decaying pair to give the expected multigamma distributions, should this process occur, for a proposed 4π detector.

Search for massive Monopoles at the Gran Sasso Laboratory with a large scale apparatus made up of scintillation counters, streamer tubes and CR-39 detectors

Abstract A large area detector to be used for a Magnetic Monopole search is in preparation. Complementary techniques, in particular the track-etch detector CR-39, will be used. The apparatus will cover a total area of at least 10 3 m 2 inside the Gran Sasso Laboratory. The role of CR-39 in the experiment and the structure of the track-etch detector are presented in this paper. Tests in progress are reported.

Wave equation for a magnetic monopole

We show that there is room, in the Dirac equation, for a massless monopole. The basic idea is that the Dirac equation admits a second electromagnetic minimal coupling associated to the chiral gauge $$e^{i\gamma _5 \theta }$$ , which is only valid for a massless particle, but satisfies all the symmetry laws of a monopole. In the problem of the diffusion on a central electric field, we find the Poincare integral and the Dirac relationeg/ħ=n/2. The latter is deduced as a consequence of the fact (which is shown in this paper) thateg/c is the projection of the total angular momentum on the symmetry axis of the system formed by the monopole and the electric charge. Another important property is that a monopole and an antimonopole have opposite helicities (as for the neutrino), but do not have opposite charges: this precludes a vacuum magnetic polarization which would be analogous to the electric one, but allows us to imagine an aether made up of monopole-antimonopole pairs. The theory is then generalized on the basis of a nonlinear equation which is the most general invariant equation under the chiral gauge law. This equation admits solutions corresponding to massive monopoles, among which there are bradyons (i.e., ordinary massive particles) and tachyons. This equation is shown to be closely related to previous works initiated by Hermann Weyl, on Dirac's theory in the framework of general relativity. In conclusion, it is suggested that massless monopoles are perhaps excited states of the neutrino and that they may be produced in some weak interactions. Consequences on the solar activity are considered.