120381541
Experimental study of pi- p ---> pi- n* at 8 and 16 gev/c
121141376
Charged Multiplicity Associated with Transverse Momentum of a Leading Proton in pp at 28.5 GEV/C
We have measured the mean charged multiplicity nCH as a function of transverse momentum p⊥ of the forward proton in the reaction p + p ⇒ p + MM for five intervals of missing mass MM using our Multiparticle Argo Spectrometer System. We observe an increase of nCH for p⊥ > 1 GeV/c.
125174279
Design and performance of the multiparticle argo spectrometer system
Abstract The Multiparticle Argo Spectrometer System, MASS, consists of a magnetic vertex spectrometer, two external trigger spectrometers, an on-line monitoring system and an off-line data analysis chain. The performance of MASS has been evaluated from physics data taken in a study of 28.5 GeV/ c pp collisions covering a large range of transverse momentum.
115233092
Asymmetry in Angular Distribution of Neutrons from Muon Capture in Spin 0 Nuclei.
121981552
Observation and study of centrally produced pion clusters in 28. 5-GeV/c p-p interactions
A double-arm spectrometer is used to identify a pion cluster produced in central p-p collisions at 28.5 GeV/c. Cluster properties studied are angular momentum, quantum statistics, multiplicity, and effective mass. There is some speculation on the production mechanism. (AIP)
139640917
Effects of Channel Failure Rates on the Jet Reconstruction Efficiencies an Resolutions in an Fe HF Calorimeter
13369520
Geodesics, the Equivalence Principle and Singularities in Higher-dimensional General Relativity and Braneworlds
The geodesics of a spacetime seldom coincide with those of an embedded submanifold of co-dimension one. We investigate this issue for higher-dimensional general relativity-like models, firstly in the simpler case without branes to isolate which features are already present, and then in the more complicated case with branes. The framework in which we consider branes is general enough to include asymmetric braneworlds but not thick branes. We apply our results on geodesics to study both the equivalence principle and cosmological singularities. Among the models that we study, these considerations favour Z2 symmetric braneworlds with a negative bulk cosmological constant.
119270516
An interpretation of variational principles for gauge theories: a cyclic coordinate alternative to ADM split
I show that there is an ambiguity in how one treats auxiliary variables in gauge theories including general relativity cast as 3 + 1 geometrodynamics. Auxiliary variables may be treated pre-variationally as multiplier coordinates or as the velocities corresponding to cyclic coordinates. The latter treatment works through the physical meaninglessness of auxiliary variables' values applying also to the end points (or end spatial hypersurfaces) of the variation, so that these are free rather than fixed. (This is also known as variation with natural boundary conditions.) Further principles of dynamics workings such as Routhian reduction and the Dirac procedure are shown to have parallel counterparts for this new formalism. One advantage of the new scheme is that the corresponding actions are more manifestly relational. While the electric potential is usually regarded as a multiplier coordinate and Arnowitt, Deser and Misner have regarded the lapse and shift likewise, this paper's scheme considers new flux, instant and grid variables whose corresponding velocities are, respectively, the above-mentioned previously used variables. This paper's way of thinking about gauge theory furthermore admits interesting generalizations as regards variational principles for the conformal form of general relativity's initial value problem.
10694441
Strong-Coupled Relativity Without Relativity
GR can be interpreted as a theory of evolving 3-geometries. A recent such formulation, the 3-space approach of Barbour, Foster and Ó'Murchadha, also permits the construction of a limited number of other theories of evolving 3-geometries, including conformal gravity and strong gravity. In this paper, we use the 3-space approach to construct a 1-parameter family of theories which generalize strong gravity. The usual strong gravity is the strong-coupled limit of GR, which is appropriate near singularities and is one of very few regimes of GR which is amenable to quantization. Our new strong gravity theories are similar limits of scalar-tensor theories such as Brans–Dicke theory, and are likewise appropriate near singularities. They represent an extension of the regime amenable to quantization, which furthermore spans two qualitatively different types of inner product.We find that these strong gravity theories permit coupling only to ultralocal matter fields and that they prevent gauge theory. Thus in the classical picture, gauge theory breaks down (rather than undergoing unification) as one approaches the GR initial singularity.
17420273
Seminar on Records Theory
In quantum gravity, one seeks to combine quantum mechanics and general relativity. In attempting to do so, one comes across the `problem of time' impasse: the notion of time is conceptually different in each of these theories. In this seminar, I consider the timeless records approach toward resolving this. Records are localized, information-containing subconfigurations of a single instant. Records theory is the study of these and of how science (or history) is to be abstracted from correlations between them. I explain how to motivate this approach, provide a ground-level structure for it and discuss what kind of further tools are needed. For a more comprehensive account with many more references, see [1].
16649409
Emergent semiclassical time in quantum gravity: I. Mechanical models*
The emergent semiclassical time approach to resolving the problem of time in quantum gravity is considered in the arena of relational particle toy models. In situations with 'heavy' and 'light' degrees of freedom, two notions of emergent semiclassical WKB time emerge; these are furthermore equivalent to two notions of emergent classical 'Leibniz–Mach–Barbour' time. I study the semiclassical approach, in a geometric phase formalism, extended to include linear constraints, and with particular care to make explicit the approximations and assumptions used, which are an important part of the semiclassical approach. I propose a new iterative scheme for the semiclassical approach in the cosmologically motivated case with one heavy degree of freedom. I find that the usual semiclassical quantum cosmology emergence of time comes hand in hand with the emergence of other qualitatively significant terms, including back-reactions on the heavy subsystem and second time derivatives. I take my analysis further for relational particle models with linearly coupled harmonic oscillator potentials, which, being exactly soluble by means outside the semiclassical approach to quantum cosmology, are additionally useful for testing the justifiability of some of the approximations and assumptions habitually made therein. Finally, I contrast emergent semiclassical time with its hidden dilational Euler time counterpart.