119386333
Canonical general relativity on a null surface with coordinate and gauge fixing
We use the canonical formalism developed together with David Robinson to study the Einstein equations on a null surface. Coordinate and gauge conditions are introduced to fix the triad and the coordinates on the null surface. Together with the previously found constraints, these form a sufficient number of second-class constraints so that the phase space is reduced to one pair of canonically conjugate variables: and . The formalism is related to both the Bondi - Sachs and the Newman - Penrose methods of studying the gravitational field at null infinity. Asymptotic solutions in the vicinity of null infinity which exclude logarithmic behaviour require the connection to fall off like after the Minkowski limit. This, of course, gives the previous results of Bondi - Sachs and Newman - Penrose. Introducing terms which fall off more slowly leads to logarithmic behaviour which leaves null infinity intact, allows for meaningful gravitational radiation, but the peeling theorem does not extend to in the terminology of Newman - Penrose. The conclusions are in agreement with those of Chrusciel, MacCallum and Singleton. This work was begun as a preliminary study of a reduced phase space for quantization of general relativity.
119537735
Newman‐Penrose Constants and Their Invariant Transformations
The origin and significance of the Newman‐Penrose (N‐P) constants of the motion are examined from the point of view that constants of the motion generate invariant transformations. Here the calculation makes use of a generalization of Green's theorem to a situation applicable to the coupled Einstein‐Maxwell fields in general relativity. One finds strictly electromagnetic constants generated by an incoming electromagnetic shock wave, with dipole symmetry, at future null infinity. The gravitational constants contain an admixture from the electromagnetic field. They are generated by an incident quadrupole gravitational shock wave at future null infinity (J+). Both the electromagnetic dipole field and the gravitational quadrupole field behave like linearized fields at J+. All higher‐multipole fields do not uncouple from the nonlinear corrections induced by the self‐coupling of the gravitational field and its coupling with the electromagnetic field. It is shown that the gravitational constants are related to t...
35621396
Conserved quantities at spatial and null infinity: The Penrose potential.
We define a superpotential for energy-momentum and rotation momentum which is built out of the conformal tensor and a bivector. This superpotential is identified with that used by Penrose in his definition of quasilocal energy. It is applied to the definition of energy-momentum and rotation momentum at spatial and at null infinities. At spatial infinity the results are in agreement with those of Ashtekar and Hansen. At null infinity the results are unsatisfactory; they are tied to a specific Bondi frame. Thus, they are not in agreement with the results of Tamburino and Winicour, Geroch and Winicour, nor with those of Dray and Streubel. Some reasons for this failure are discussed.
120204158
Developments and predictions
117256701
Limiting behavior of asymptotically flat gravitational fields
AbstractCouch and Torrence suggest that the vacuum Einstein equations admit a larger class of asymptotically flat solutions than those exhibiting the peeling property. Starting with the assumption that
$$\Psi _0  = O(r^{ - 2 - \varepsilon _0 } )$$
, (d/dr)
$$\Psi _0  = O(r^{ - 3 - \varepsilon _0 } )$$
 and (δ/δxA)
$$\Psi _1  = O(r^{ - 2 - \varepsilon _0 } )$$
, wherexA (A = 2, 3) are angular coordinates, they show that
$$\Psi _1  = O(r^{ - 2 - \varepsilon _1 } )$$
, where ε1⩽ 2 and ε1<ε0;
$$< \varepsilon _0 ;\Psi _2  = O(r^{ - 2 - \varepsilon _2 } )$$
, where ε2 ⩽ 1 and ε1< ε1; and Ψ4 and Ψ3 peel as they would under the stronger peeling conditions. The Winicour-Tamburino energy-momentun and angular momentum integrals for these solutions, in general, diverge. In fact, since Couch and Torrence determine only the radial dependence of the solution, it is not clear that the solutions are well defined. We find that the stronger assumption
$$\Psi _0  = O(r^{ - 3 - \varepsilon _0 } )$$
, (d/dr)
$$\Psi _0  = O(r^{ - 4 - \varepsilon _0 } )$$
, and (δ/δxA)
$$\Psi _0  = O(r^{ - 3 - \varepsilon _0 } )$$
 does result in well-defined solutions for which both the energy-momentum and angular momentum intergrals are not only finite but result in the same expressions as are obtained for peeling space-times. This assumption appears to be the minimal assumption that is necessary for investigating outgoing radiation at null infinity.
119857978
ASYMPTOTIC INVARIANTS IN GRAVITATIONAL RADIATION FIELDS
Asymptotic integral invariants are constructed for the electromagnetic and gravitational fields. The integrals are taken over closed two-dimensional surfaces embedded in a null hypersurface. In the absence of incoming radiation the asymptotic behavior of the electromagnetic field F/sup ab/ and the Riemann tensor R/sub abcd/ is such that the integrals formed with these quantities are independent of the particular space-like surface of integration, as long as it lies in the same null hypersurface. Therefore, the integrals are related to the multipole structure of the charge distribution please delete the above abstract no. 31658=====
123460442
A new high gain thin gap detector for the opal hadron calorimeter
Abstract A new type of thin gap multiwire gas detector operating in a high gain mode has been developed for use in the OPAL pole tip calorimeter. The detector thickness is only 6.6 mm and its area is 0.61 m 2 . The induced pad readout provides high output pulses which require no amplification. The set-up for the detector mass production and quality control test is described. Results from a test beam set-up that simulates the OPAL pole tip calorimeter are presented and compared with computer simulations.
16978878
What is the statistical significance of the solar neutrino flux problem
Uniform random numbers, not Gaussian random numbers, should have been used with Standard Solar Models to estimate the effect on the neutrino flux of uncertainties in input data. The observed discrepancy is therefore probably quite smaller than currently accepted.
123161968
A new description of high energy antiproton (proton)-proton elastic scattering
Abstract We develop a generalization of the geometric picture for high-energy antiproton (proton)-proton elastic scattering. The eikonal at each impact parameter is considered to have fluctuations about an average value, and is thus characterized by a distribution. A connection to parton branching is made through the specific form of the distribution function for the eikonal. A unified physical theory with significant fluctuations accurately describes the p(p)-p data at both s =546 GeV and 53 GeV. The fluctuation parameter is remarkably well given by that directly observed in multiparticle production.
118402616
Comment on Jerrold Franklin, Superluminal neutrinos, arXiv:1110.0234v1
A reasonably short antineutrino run using OPERA and/or MINOS may test J. Franklin's explanation of recently claimed $\nu_\mu$ superluminality.