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8
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84931481546
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It is useful to bear in mind that this is based on a purely classical analysis and that quantum fluctuations (near the end of inflation) in the curvature of spatial hypersurfaces are likely to invalidate this conclusion (possibly, to a part in 104 on the scale of the horizon);
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34
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84931481548
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One would hope that an explanation of this coincidental similarity can be achieved consistent with the requirement that the scalar field and the baryonic fluid interact, if at all, only exceedingly weakly.
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35
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84931481541
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In Ref. 17 we presented contours of three cosmological parameters in the two-dimensional ( ΩB, α ) parameter space for the power-law potential models ( alpha is the power-law index of the scalar-field potential). If the cosmological measurements converge to select a point in the ( ΩB, α ) space, this will be strong circumstantial evidence for a power-law potential model. Other scalar-field potential models may be compared to the observational data in a similar manner. At this stage we can make no further observational predictions. However, once a detailed model for entropy production and galaxy formation is constructed, these models should have further observational consequences.
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42
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84931481540
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In the standard superstring scenario, it is believed that once supersymmetry is broken string-loop corrections will generate a potential for the dilaton. It is hoped that the form of this potential will ensure that the resulting time variation of the dilaton ``vacuum'' expectation value (and hence that of coupling constants such as the fine-structure constant which depend on the dilaton ``vacuum'' expectation value) does not conflict with observational bounds on the time variation of fundamental constants.
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43
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84931481539
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A simple-minded analysis (which ignores the need to compactify the higher-dimensional superstring theory) suggests that it might be difficult to reconcile a slowly rolling dilaton ``vacuum'' expectation value with the observational bounds on the time variation of fundamental constants.
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45
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84931481535
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A. Sandage and G. A. Tammann, in Large-Scale Structure of the Universe, edited by G. Setti and L. Van Hove ESO CERN report, 1984;
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47
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84931481533
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If one was willing to depart even further from the conventional inflation modified hot big-bang scenario, it is conceivable that this small ratio could be increased, even closer, towards unity.
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48
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84931481532
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G. 't Hooft, in Recent Developments in Gauge Theories, edited by G. 't Hooft et al.. (Plenum, New York, 1980).
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49
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84931481538
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In our models there are really two, somewhat different, facets of the cosmological-constant ``problem.'' There is the issue of preserving the shape of the potential as well as the issue of ensuring that the energy at the global minimum of the potential is exceedingly small, compared to the Planck scale.
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50
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84931481537
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In any current, satisfactory, theory of particle physics, the cosmological constant at low energies is, essentially, a free parameter. This even seems to be true in superstring theories (at least at the present stage of their development), since the symmetry (supersymmetry) which might ensure that LAMBDA vanishes at the Planck scale must be broken below >wig 1 TeV. In the absence of a theory which determines the value of the cosmological constant and in the absence of conclusive observational evidence that Λ =0 (in fact the observational data is not inconsistent with the existence of a LAMBDA energy density an order of magnitude larger than the present energy density in baryons), the only option seems to be to study the observational consequences of models with a nonvanishing cosmological ``constant.''
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60
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84931481569
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DESY Reports Nos. DESY 87-122 and DESY 87-123, 1987 (unpublished), and references therein.
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Wetterich, C.1
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68
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84931481571
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report, 1987 (unpublished).
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Weiss, N.1
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86
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84931481570
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In the standard inflationary scenario, sufficient entropy is expected to be generated during the period of rapid damped scalar oscillations about the minimum of the potential. We are unaware of a comprehensive study of this part of the canonical scenario. In our models, it might be possible to produce entropy if V( Φ ) had a local minimum followed by a local maximum, before the epoch when PHI begins to roll. However, with such a potential some regions of the Universe might get stuck in the local minimum, possibly leading to a problem similar to that in the original model of inflation. It is for this reason that we have suggested an alternate mechanism for the production of entropy.
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87
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84931481565
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The cosmological consequences of our models do not depend on the parity of the scalar field. In certain cases a pseudoscalar field might be more desirable than a scalar field (although this does restrict the form of the potential). The forces mediated by a pseudoscalar coupled to ordinary matter are usually more difficult to detect than the scalar mediated force;
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89
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84931481564
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It is, at present, unclear whether sufficient entropy can be generated in such pseudoscalar models.
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93
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84931481567
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V. I. Arnold, Ordinary Differential Equations (MIT, Cambridge, MA, 1981); C. M. Bender and S. A. Orszag, Advanced Mathematical Methods for Scientists and Engineers (McGraw-Hill, New York, 1978); E. A. Coddington and N. Levinson, Theory of Ordinary Differential Equations (Krieger, Melbourne, Fl, 1984); H. T. Davis, Introduction to Nonlinear Differential and Integral Equations (USAEC, Washington, D.C., 1960).
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101
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84931481566
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and references therein.
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