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.
110040760
On Line Data Analysis of High Energy P-P Scattering Experiment
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)
122516925
Isobar production and elastic scattering in p p interactions from 6-GeV/c to 30-GeV/c
122807269
Observation of increasing charged multiplicity as a function of transverse momentum in 28.5-GeV/c pp interactions
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.
14761899
Leibniz--Mach foundations for GR and fundamental physics
Consider the configuration space Q for some physical system, and a continuous group of transformations G whose action on the configurations is declared to be physically irrelevant. Implement G indirectly by adjoining 1 auxiliary g per independent generator of G to Q, by writing the system's action in an arbitrary G-frame (G-AF), and then passing to the quotient Q/G thanks to the constraints encoded by g-variation. I show that this G-AF principle supercedes (and indeed leads to a derivation of) the Barbour--Bertotti (BB) best matching principle. My other consideration is that absolute external time is meaningless for the universe as a whole. For various choices of Q and G, these lead to BB's proposed absolute structure free replacement of Newtoninan mechanics, to Gauge Theory and to the 3-space approach (TSA) formulation of GR. For the latter with matter fields, I discuss the SR postulates, Principle of Equivalence (POE) and simplicity postulates. I explain how a full enough set of fundamental matter fields to describe nature can be accommodated in the TSA, and compare the TSA with the `split spacetime formulation' of Kuchar. I explain the emergence of broken and unbroken Gauge Theories as a consequence of the POE. I also consider as further examples of the G-AF principle the further quotienting out of conformal transformations (CT) or volume preserving CT. Depending on which choices are made, this leads to York's initial value formulation (IVF) of GR, new alternative foundations for it, or alternative theories of gravity built out of similar conformal mathematics which nevertheless admit no GR-like spacetime interpretation.
18221317
Emergent semiclassical time in quantum gravity: II. Full geometrodynamics and minisuperspace examples
I apply the preceding paper's emergent semiclassical time approach to geometrodynamics. The analogy between the two papers is useful at the level of the quadratic constraints, while I document the differences between the two due to the underlying differences in their linear constraints. I find that the emergent time-dependent wave equation for the universe in general not a time-dependent Schrodinger equation but rather a more general equation containing second time derivatives, and estimate in which regime this becomes significant. I provide a specific minisuperspace example for my emergent semiclassical time scheme and compare it with the hidden York time scheme. Overall, interesting connections are shown between Newtonian, Leibniz-Mach-Barbour, Wentzel-Kramers-Brillouin (WKB) and cosmic times, while the Euler and York hidden dilational times are argued to be somewhat different from these.
17480703
Interacting vector fields in relativity without relativity
Barbour, Foster and O Murchadha have recently developed a new framework, called here the 3-space approach, for the formulation of classical bosonic dynamics. Neither time nor a locally Minkowskian structure of spacetime are presupposed. Both arise as emergent features of the world from geodesic-type dynamics on a space of three-dimensional metric–matter configurations. In fact gravity, the universal light-cone and Abelian gauge theory minimally coupled to gravity all arise naturally through a single common mechanism. It yields relativity—and more—without presupposing relativity. This paper completes the recovery of the presently known bosonic sector within the 3-space approach. We show, for a rather general ansatz, that 3-vector fields can interact among themselves only as Yang–Mills fields minimally coupled to gravity.
14723293
On the recovery of geometrodynamics from two different sets of first principles
Abstract The conventional spacetime formulation of general relativity may be recast as a dynamics of spatial 3-geometries (geometrodynamics). Furthermore, geometrodynamics can be derived from first principles. I investigate two distinct sets of these: (i) Hojman, Kuchař and Teitelboim's, which presuppose that the spatial 3-geometries are embedded in spacetime. (ii) The 3-space approach of Barbour, Foster, O Murchadha and Anderson in which the spatial 3-geometries are presupposed but spacetime is not. I consider how the constituent postulates of the conventional approach to relativity emerge or are to be built into these formulations. I argue that the 3-space approach is a viable description of classical physics (fundamental matter fields included), and one which affords considerable philosophical insight because of its ‘relationalist’ character. From these assumptions of less structure, it is also interesting that conventional relativity can be recovered (albeit as one of several options). However, contrary to speculation in the earlier 3-space approach papers, I also argue that this approach is not selective over which sorts of fundamental matter physics it admits. In particular, it does not imply the equivalence principle.
117105066
PDE system approach to large extra dimensions
We explore some foundational issues regarding the splitting of D-dimensional Einstein Field Equations (EFE’s) with respect to timelike and spacelike (D - 1)-dimensional hypersurfaces, first without and then with thin matter sheets such as branes. We begin to implement methodology, that is well-established for the GR Cauchy and initial value problems (CP and IVP), in the new field of GR-based braneworlds, identifying and comparing many different choices of procedure. We abridge fragmentary parts of the literature of embeddings, putting the Campbell–Magaard theorem into context. We recollect and refine arguments why York and not elimination methods are used for the GR IVP. We compile a list of numerous mathematical and physical impasses to using timelike splits, whereas spacelike splits are known to be well-behaved. We however pursue both options to make contact with the current braneworld literature which is almost entirely based on timelike splits. In our study of timelike splits, we look at the Shiromizu–Maeda–Sasaki braneworld by means of reformulations which emphasize different aspects from the original formulation. We show that what remains of the York method in the timelike case generalizes heuristic bulk construction schemes. We formulate timelike (brane) versions of the thin sandwich conjecture. We discuss whether it is plausible to remove singularities by timelike embeddings. We point out how the braneworld geodesic postulates lead to futher difficulties with the notion of singularities than in GR where these postulates are simpler. Having argued for the use of the spacelike split, we study how to progress to the construction of more general data sets for spaces partially bounded by branes. Boundary conditions are found and algorithms provided. Working with (finitely) thick branes would appear to facilitate such a study.