Observers in Kerr spacetimes: the ergoregion on the equatorial plane

We perform a detailed analysis of the properties of stationary observers located on the equatorial plane of the ergosphere in a Kerr spacetime, including light-surfaces. This study highlights crucial differences between black hole and the super-spinner sources. In the case of Kerr naked singularities, the results allow us to distinguish between “weak” and “strong ” singularities, corresponding to spin values close to or distant from the limiting case of extreme black holes, respectively. We derive important limiting angular frequencies for naked singularities. We especially study very weak singularities as resulting from the spin variation of black holes. We also explore the main properties of zero angular momentum observers for different classes of black hole and naked singularity spacetimes.     

Magnetic charge,black holes,and cosmic censorship

The possibility of converting a Reissner-Nordström black hole into a naked singularity by means of test particle accretion is considered. The dually charged Reissner-Nordström metric describes a black hole only when M² > Q³ + P². The test particle equations of motion are shown to allow test particles with arbitrarily large magnetic charge/mass ratios to fall radially into electrically charged black holes. To determine the nature of the final state (black hole or naked singularity) an exact solution of Einstein's equations representing a spherical shell of magnetically charged dust falling into an electrically charged black hole is studied. Naked singularities are never formed so long as the weak energy condition is obeyed by the infalling matter. The differences between the spherical shell model and an infalling point test particle are examined and discussed.     

Destroying Extremal Kerr-Newman-AdS Black Holes with Test Particles

Neglecting the self-force,self-energy and radiative effects,we follow the spirit of Wald's gedanken experiment and further discuss whether an extremal Kerr-Newman-AdS(KNA)black hole can turn into a naked singularity when it captures charged and spinning massive particles.It is found that feeding a test particle into an extremal KNA black hole could lead to a violation of cosmic censorship for the black hole.     

Gravity beyond quantum theory: Electron as a closed heterotic string

The observable gravitational and electromagnetic parameters of an electron determine that its background should be the Kerr-Newman (KN) solution of the rotating black hole without horizons. This metric has a topological defect—the Kerr singular ring which, as we show, is a closed heterotic string of the Compton radius a = ?/(2m). We show that the Dirac equation emerges as a consequence of the underlying KN gravity and string theory. Regularization of the KN solution leads to a model of gravitating soliton of the oscillon type, in which the closed heterotic string is positioned on the edge rim of a disklike vacuum bubble. It is suggested that the string-like core of the electron should be experimentally observable by the novel methods of the “Deeply Virtual (nonforward) Compton scattering”.     

Destroying a Near-Extremal Kerr-Newman-AdS Black Hole with Test Particles

If radiative and self-force effects are neglected, we find that feeding a test particle into a near-extremal KerrNewman-Ad S black hole could lead to destroy their event horizon, giving rise to naked singularities. Hence radiative and self-force effects must be taken into account to further test cosmic censorship. Moreover, the allowed parameter range for this test particle is very narrow, this leaves the possibility of radiative and self-force effects considerations to cure the problem of WCC violation in Kerr-Newman-Ad S spacetime.     

Weak Gravitational Lensing from Regular Bardeen Black Holes

In this article we study weak gravitational lensing of regular Bardeen black hole which has scalar charge g and mass m. We investigate the angular position and magnification of non-relativistic images in two cases depending on the presence or absence of photon sphere. Defining dimensionless charge parameter \(q=\frac {g}{2m}\) we seek to disappear photon sphere in the case of \(|q|>{24\sqrt 5}/{125}\) for which the space time metric encounters strongly with naked singularities. We specify the basic parameters of lensing in terms of scalar charge by using the perturbative method and found that the parity of images is different in two cases: (a) The strongly naked singularities is present in the space time. (b) singularity of space time is weak or is eliminated (the black hole lens).     

New evaluation of muon (g − 2) hadronic anomaly

The hadronic part a_H of the muon g-factor anomaly $\text{a ≡}\text{(g ? 2)}\text{2}$ is evaluated from latest data on σ(e⁺e^? → hadrons). For a p-wave ππ scattering length of a₁ = 0.04±0.005 we calculate a_H = (66±10) × 10^?9, compared to a(experiment) ? a(QED) = (60±29) × 10^?9. Half of the uncertainty on a_H is associated with the energy interval $\text{0.92 <}\text{s}\text{< 2}\text{GeV}$.     

Quantum gravitational bubbles

Spacetime is expected to have a “foamlike” structure on scales of the Planck length or less with high curvatures and complicated topology. This foam can be thought of as being built out of three basic kinds of units or “gravitational bubbles”, CP², S² × S² and K3. We investigate the propagation of particles in simple models of the first two types of bubble. The non-trivial topologies of the bubbles introduce extra singularities into the Green functions. These make large contributions to the S-matrix for scalar particles but only small contributions for $\text{spin}\text{-}\text{1}\text{2}$ or 1 particles at energies small compared to the Planck length. These results suggest that there is no inconsistency between the spacetime foam picture and everyday observations from which spacetime appears nearly flat, because all the elementary particles we have observed have spin $\text{1}\text{2}$ or greater. They do, however, suggest that Higgs scalar fields, if they exist at all, are probably bound states of higher spin particles rather than being elementary fields. Further developments may enable one to calculate processes in which quantum coherence is lost and intrinsic entropy is produced.     

Rotationally resolved spectra of two van der Waals states of I + Cl

Three-step optical resonance is used to execute state-selected transitions from the ground state of ICl to two van der Waals states, $\text{b(}\text{Ω}\text{= 1)}$ and $\text{b′(}\text{Ω}\text{= 2)}$, both of which correlate with the second dissociation limit, $\text{I}\text{(}{}^2\text{P}{}_{\mathrm{<mtext>3</mtext><mtext>2</mtext>}}\text{) +}\text{Cl}\text{(}{}^2\text{P}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{)}$, of ICl. Since the B(0⁺) state also belongs to this limit, three out of five states converging to I + Cl¹ are now accounted for. Principal constants of these states are: b′(2): T_e = 18275.84, ω_e = 31.093, ω_ex_e = 1.672, ω_ey_e = 0.0070, B_e = 0.034834, α_e = .001587, and D_e = 164.09 cm^?1; b(1): T_e = 18273.30, ω_e = 26.75, ω_ex_e = 0.882, B_e = 0.03579, q = 0.00084, and D_e = 166.63 cm^?1. In both states the equilibrium distance is near 4.2 Å, slightly greater than the sum of van der Waals contact radii, $\text{r}{}_{\mathrm{<mtext>I</mtext>}}\text{+ r}{}_{\mathrm{<mtext>Cl</mtext>}}\text{= 3.95}\text{A}\text{?}$. The large value of q in the b(1) state indicates that, in the basis set $\text{|j}{}_{\mathrm{a}}\text{j}{}_{\mathrm{b}}\text{j}\text{Ω}\text{〉}$ (a = I, b = Cl, j = j_a + j_b) the b(1) and b′(2) states belong to j = 1 and j = 2 “complexes,” respectively.     

Geometry of rotating charged bubbles in general relativity

It is shown that the spatial geometry of the bubbles with a constant radial coordinater _o, embedded in the Kerr-Newman manifold, does not depend on the mass and charge of this solution when referred to a coordinate frame rigidly rotating with the angular velocity =a(r ₀ ^{2+a 2})^–1. The corresponding line element is found to be identical to the one obtained by Smarr for the surface geometry of a charged rotating black hole.     

Repulsive Gravitation in the Kerr-Newman Field

It is shown that uncharged test particles, released from rest at infinity in the Kerr-Newman field, stop and rebound when the radial coordinate r takes the value r₀ = Q²/(2M). This expression corresponds to the position of a stationary source of the Kerr-Newman field found by the author. It represents the surface of a massive oblate ellipsoid of revolution undergoing rigid rotation. Besides, the magnitude of r₀ guarantees that no violation of causality occurs throughout spacetime. Although the test particles' angular momenta are always zero, they acquire a rotational motion as a consequence of the dragging of inertial frames.     

Solutions of the Einstein-Maxwell equations with many black holes

In Newtonian gravitational theory a system of point charged particles can be arranged in static equilibrium under their mutual gravitational and electrostatic forces provided that for each particle the charge,e, is related to the mass,m, bye=G ^1/2 m. Corresponding static solutions of the coupled source free Einstein-Maxwell equations have been given by Majumdar and Papapetrou. We show that these solutions can be analytically extended and interpreted as a system of charged black holes in equilibrium under their gravitational and electrical forces.We also analyse some of stationary solutions of the Einstein-Maxwell equations discovered by Israel and Wilson. If space is asymptotically Euclidean we find that all of these solutions have naked singularities.Alfred P. Sloan Research Fellow, supported in part by the National Science Foundation.     

Vierbein singularities in CP2

The compact open four-dimensional manifold $\text{C}$P², with Euclidean metric, has recently attracted attention as an example of a spacetime in which fields of half-integral spin cannot be defined in the absence of additional structure (such as an electromagnetic background). In this note we identify the specific topological anomaly responsible for this phenomenon: $\text{C}$P² contains a class of two-dimensional spheres—“complex lines”— in small neighborhoods of each of which the two transverse degrees of freedom are forced to “twist” in a characteristic way. It is shown in detail how the twists force vierbeins—tetrads of orthonormal vector fields that play a central role in the theory of spinors—to have singularities on every complex line. As an aid to visualization we construct an example of a vierbein with, loosely speaking, the smallest possible set of singularities: It is ill-defined at every point of some one complex line and smooth everywhere else. The behavior of such a vierbein near any one of its singular points is characterized explicitly. The structure of the minimally singular vierbein is used to illuminate the observation of Hawking and Pope that in the presence of an appropriate electromagnetic background, fields of any spin can exist on $\text{C}$P² as long as their electric charges are correctly quantized, but that the charge values available to half-integral-spin fields differ from those available to integral-spin fields.     

Supersymmetry of the extreme rotating toroidal black hole

We study the supersymmetry of the charged rotating toroidal black hole solutions found by Lemos and Zanchin, and show that the only configurations that are supersymmetric are: (i) the non-rotating electrically charged naked singularities already studied by Caldarelli and Klemm, and (ii) an extreme rotating toroidal black hole with zero magnetic and electric charges. For this latter case, the extreme uncharged black hole, we calculate the Killing spinors and show that the configuration preserves the same supersymmetries as the background spacetime.     

Magnetic moments of composite fermions

There have been a considerable number of papers proposing composite models for leptons and quarks. Recently, Glück and Lipkin have stated that reproducing the observed magnetic moments of these fermions presents a serious difficulty for these composite models. We show for a renormalizable theory that, in contrast to Glück's and Lipkin's nonrelativistic arguments, a deeply bound system (with heavy constituent particle masses m_c) of (total) spin $\text{1}\text{2}$, charge e and mass m has the magnetic moment $\text{(e/2m) [1 +}\text{“usual” (QED + QCD + weak) corrections +O}\text{(m/m}{}_{\mathrm{<mtext>c</mtext>}}\text{)}\text{“new” bindng corrections]}$. Although there remains the considerable dynamical problem of obtaining “light” bound fermions from heavy constituents, there is no separate, additional magnetic moment difficulty.     

Magnetic behaviour of single crystal anhydrous cupric chloride in the low temperature ordered phase

A “spin-flop” transition has been observed in anhydrous cupric chloride. The antiferromagnetic exchange field, H_e, is of the order of 10⁶ Oe so that only the spin-flop field can be measured: this gives H_sf = 4.1 × 10⁴ Oe. The ratio of the anisotropy field, H_a, which also acts in the crystal, to H_e is estimated as $\text{H}{}_{\mathrm{<mtext>a</mtext>}}\text{H}{}_{\mathrm{<mtext>e</mtext>}}\text{～ 8.4 × 10}{}^{\mathrm{?4}}$.     

An Analytic Approximation for Researching Tunneling Rate from Black Hole in Proca Field

The analytic solution of a static spherical symmetrical Proca black hole is discussed in this paper. As in the massive vector field, Proca black hole can be considered as the analogy of RN background plus a perturbation with the same order as μ ² due to the mass of vector particle μ satisfying μ ² ? 1. Through the action of Proca field, we find the analytic form with the first and arbitrary order approximation. Furthermore, we divide the results into 3 groups according to the real zero solutions of the background (i.e., spacetime in massless vector field). Finally we analyze the Hawking radiation of such black hole, which is significant for constructing black hole thermodynamic.     

Estimate of fusion through deuteron-ionic halide interaction

The possibility of attaining the fusion reactions ¹⁹F(d,n)²⁰Ne, or ¹⁹F(d,p)²⁰F through coupling of a fluorine ion and a deuteron is discussed. Approximation of the ground state of this effective “bose atom” yields the following expression for the transmission coefficient for penetration of the deuteron through nuclear Coulomb barrier: $\text{T=}\text{exp}\text{[?2πZ(2s)}{}^{\mathrm{<mtext>3</mtext><mtext>4</mtext>}}\text{(}\text{m}{}_{\mathrm{<mtext>d</mtext>}}\text{20m}{}_{\mathrm{<mtext>e</mtext>}}\text{)}{}^{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{]}$. The radius of the F^? ion is sa₀ and deuteron-to-electron mass is m_d/m_e. Thus, T is infinitesimal and the assumed model renders the said fusion reaction highly improbable.