J. R. Ellis, J. S. Hagelin, D. V. Nanopoulos and M. Srednicki, Nucl. Phys. B 241 (1984) 381.  Home/Search   Document Not in Database   Summary   Related Articles   Check

....of dilaton dark matter. To appear in Phys. Lett. B Relaxed bounds on the dilaton mass in a string cosmology scenario. It is known that the coherent oscillations around the minimum of the potential of a cosmic scalar background [1 4] such as the dilaton [5 7], put severe cosmological bounds on the allowed value of the mass m of that scalar field. Such oscillations, however, become coherent, and then constrain the mass, only when the possible spatial inhomogeneities of the background are negligible. Spatial inhomogeneities of the dilaton background ....

.... p ) 9) the index m means that the variable is to be evaluated at the scale H = m) The reheating from T d to T r will thus produce an entropy increase T r T d (10) In order to preserve any pre existing baryon antibaryon asymmetry, the condition should be satisfied [5 7]. Such a condition implies 14 GeV (11) This last requirement could be alleviated, however, in the case of low energy (electro weak, for instance) baryogenesis; in particular, in the case of baryogenesis associated to the dilaton decay itself [7,11] occuring at scales not much distant from ....

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J. Ellis, D. V. Nanopoulos and M. Quiros, Phys. Lett. B174 (1986) 176

....gas already present at the scale H d is in fact, from eq. 5.20) T d = T i (M p H i ) M p H 1 6 (5.24) The reheating of the radiation gas from T d to T r thus produces an entropy increase mM (5. 25) By imposing #S 10 in order to preserve nucleosynthesis [57] one obtains the bound 10 2 (5.26) The second alternative corresponds to T r TN , i.e. m GeV , and allows a nucleosynthesis phase subsequent to dilaton decay. In such case, the only phenomenological constraint is possibly imposed by primordial baryogenesis. The maximum ....

....decay. In such case, the only phenomenological constraint is possibly imposed by primordial baryogenesis. The maximum tolerable amount of entropy, in order not to wash out any pre existing baryon antibaryon asymmetry, is somewhat model dependent, but in general #S seems to be acceptable [57,58]. This implies the bound 10 10 (5.27) Note, however, that this last condition may be evaded in the case of low energy baryogenesis and, in particular, in the case of baryogenesis associated with the dilaton decay itself [55, 58] occurring at scales not much distant from ....

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J. Ellis, D. V. Nanopoulos and M. Quiros, in ref. 7

....as opposed to the ffstate case. Therefore, the initial reduced density matrix ae 0 of the parent universe determines in a unique fashion its effective density matrix ae at arbitrary time. We show in Appendix that the evolution equation for ae is a special case of the equation of refs. [19, 20]: ae = Gammai[T ; ae] Gamma 1 2 V V ae Gamma 1 2 aeV V V aeV : 10) It is straightforward to see [19] that T rae 2 decreases with time, so that quantum coherence is indeed lost for the parent universe subsystem. The authors are indebted to T. Banks, K. Lee, Kh. Nirov ....

J.Ellis, J.S.Hagelin, D.V. Nanopoulos and M.Srednicki, Nucl. Phys. B241 (1984) 381.

....[Note, however, that m I can be 10 15 GeV if cosmic strings are invoked to generate the needed initial density fluctuations. Even if one does not try to use the moduli as inflatons, the existence of light gravitationally coupled fields resurrects the infamous Polonyi problem [126] 127] [128], 129] In essence the problem is that the presence of light particles with very weak, Planck suppressed couplings causes cosmological problems, either because they decay late and generate too much entropy while failing to reheat the Universe sufficiently to restart nucleosynthesis, or because ....

J. Ellis, D.V. Nanopoulos and M. Quiros, Phys. Lett. B174, 176 (1986).

....of dilaton dark matter. To appear in Phys. Lett. B Relaxed bounds on the dilaton mass in a string cosmology scenario. It is known that the coherent oscillations around the minimum of the potential of a cosmic scalar background [1 4] such as the dilaton [5 7], put severe cosmological bounds on the allowed value of the mass m of that scalar field. Such oscillations, however, become coherent, and then constrain the mass, only when the possible spatial inhomogeneities of the background are negligible. Spatial inhomogeneities of the dilaton background can ....

.... means that the variable is to be evaluated at the scale H = m) The reheating from T d to T r will thus produce an entropy increase DeltaS = T r T d ) 3 M p m (10) In order to preserve any pre existing baryon antibaryon asymmetry, the condition DeltaS 10 5 should be satisfied [5 7]. Such a condition implies m 10 14 GeV (11) This last requirement could be alleviated, however, in the case of low energy (electro weak, for instance) baryogenesis; in particular, in the case of baryogenesis associated to the dilaton decay itself [7,11] occuring at scales not much ....

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J. Ellis, D. V. Nanopoulos and M. Quiros, Phys. Lett. B174 (1986) 176

....function has been always enigmatic. We propose here to use an explicit string derived mechanism in one interpretation of non critical string theory for the collapse of the wave function[4] involving quantum gravity in an essential way and solidifying previous intuitively plausible suggestions[5, 6]. It is an amazing surprise that quantum gravity effects, of order of magnitude G 1=2 N m p 10 Gamma19 , with GN Newton s gravitational constant and m p the proton mass, can play a role in such low energies as the eV scales of the typical energy transfer that occurs in cytoskeleta. However, ....

.... S matrix element, as was the case of critical strings [46] Instead, one has nonfactorisable contributions to a superscattering amplitude = S 6= SS y , as is usually the case in open quantum mechanical systems, where the fundamental building blocks are density matrices and not pure quantum states[5]. For completeness, we describe in Appendix A some formal aspects of this situation, based on results of our approach to non critical strings [4] It is this sort of coherence breakdown that we advocate as happening inside the part of the brain related to consciousness, whose operation is ....

J. Ellis, J.S. Hagelin, D.V. Nanopoulos and M. Srednicki, Nucl. Phys. B241 (1984), 381.

....OE j a Delta a Gamma 1 4 exp i OE f OE j F j F j a 4f OE F j F j ; where we specialized to the supersymmetric S dual case [6] in fixing the axion scale f a = ff s =2 )f OE . The observation that a CDM axion should come with a dilaton is already implicit in [7], since it was pointed out that a dilaton with a large coupling scale f OE should also meet cosmological constraints from Omega 1. It was shown in [8] that dilatons with f OE of the order of the Planck mass should acquire a mass of the order of the gravitino mass if supersymmetry is softly ....

J. Ellis, D.V. Nanopoulos and M. Quiros, Phys. Lett. B174 (1986) 176.

....can derive [13] an equation for the temporal evolution of the density matrix ae of the subsystem comprising of the Liouville dressed displacement field T ( t) in interaction with the fluctuating space time. The equation is of the generic form expected in an effective theory of quantum gravity [12]: t ae = i[ae; H] ffiH ae (23) where = ffiH is a non commutator term, depending on data of the (non critical) oe model that describes propagation of the string excitations in a non trivial black hole space time [13, 24] One can calculate in this approach the off diagonal elements of the ....

J. Ellis, J.S. Hagelin, D.V. Nanopoulos and M. Srednicki, Nucl. Phys. B241 (1984), 381.

.... and final state density matrices: ae out = Sae in (1) It has further been pointed out that, if this suggestion is correct, there must be a modification of the usual quantum mechanical time evolution of the wave function, taking the form of a modified Liouville equation for the density matrix [2]: t ae = i[ae; H] ffiH ae (2) The extra term in (2) is of the form generally encountered in the description of an open quantum mechanical system, in which observable degrees of freedom are coupled to unobservable components which are effectively integrated over, which may evolve from a pure ....

....obtained from the Hamiltonian (13) is suppressed relative to the terms obtained from the free energy. Such a suppression is necessary for the consistency of our adiabatic approximation. The term in (44) that depends on the energy content of the scalar matter field is the last one, which is of O[ 2 ], where is the mass of the scalar particle. The rest of the terms depend on details of the black hole background, and in particular on its hair [7] For extreme macroscopic black holes with m h 1 (in units of the Planck mass M P ) for instance, the dominant term is the 2 term. This ....

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J. Ellis, J.S. Hagelin, D.V. Nanopoulos and M. Srednicki, Nucl. Phys. B241 (1984), 381.

....time evolution of a quantum system must also be modified. When integrated over all time, the usual Liouville equation t ae = i[ae; H] becomes the normal S matrix description of asymptotic scattering. In order to avoid this so as to accommodate a lack of factorization (9) we need an extra term [7]: t ae = i[ae; H] ffiH ae (10) Just such a modification of the quantum Liouville equation is characteristic of open quantummechanical systems. Here, the openness would be due to the coupling of the observable system to unseen (unseeable ) modes of the theory within the microscopic event ....

....microscopic event horizons believed to infest space time. Any modification (10) would necessarily cause pure states to evolve into mixed states, with the collapse of off diagonal entries in the density matrix. One can also show that symmetries no longer correspond to conservation laws, in general [7]. Clearly, any modification of the type (10) should respect probability conservation, which means that Trae should be time independent, and it should also conserve energy, at least to a very good approximation. Shortly after the proposal (10) was made, the concern was expressed [8] that energy ....

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J. Ellis, J.S. Hagelin, D.V. Nanopoulos and M. Srednicki, Nucl. Phys. B241 (1984), 381.

....Universe, its large entropy and its closeness to the critical density. Inflation occurs for generic scalar field potentials, but these may not fit naturally within a conventional Grand Unified field theory. A number of proposals have been made for the accommodation of inflation within string theory[3, 4], but these are also beset with difficulties. At the level of an effective field theory derived from an underlying string theory, it becomes even more difficult to generate naturally a suitable inflationary scalar potential. Some such scenaria have inflationary epochs that are too short and or ....

....the level of an effective field theory derived from an underlying string theory, it becomes even more difficult to generate naturally a suitable inflationary scalar potential. Some such scenaria have inflationary epochs that are too short and or inhomogeneous density fluctuations that are too large[3]. However, we do not rule out the possibility that a realistic scenario may emerge under certain extra assumptions. A more fundamental approach has been to study full string theories in timedependent backgrounds[5] in the hope of identifying string solutions of cosmological interest that could ....

J. Ellis, K. Enqvist, D.V. Nanopoulos and M. Quiros, Nucl. Phys. B277 (1986), 231;

....massive [37] In no scale supergravity models, the masses of these scalars (and the gravitino as well) are not determined at the tree level, despite the local breaking of supersymmetry. If these masses are large, as in [37] there is no longer a problem with either the scalars or the gravitino [38]. So long as the masses of the scalars are more than 10 Gamma8 M P , there is no appreciable entropy production [39] and if the scalar masses are larger than 10 Gamma12 M P they never dominate the energy density [27] and are therefore acceptable. Below this mass, the scalars do ....

J. Ellis, D.V. Nanopoulos and M. Quiros, Phys. Lett. B174 (1986) 176.

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J. R. Ellis, J. S. Hagelin, D. V. Nanopoulos and M. Srednicki, Nucl. Phys. B 241 (1984) 381.

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J. Ellis, D. V. Nanopoulos and M. Quiros, Phys. Lett. B174, 176 (1986); J. Ellis, C. Tsamish and M. Voloshin, Phys. Lett. B194, 291 (1987).

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J. Ellis, D. V. Nanopoulos and M. Quiros, Phys. Lett. B174, 176 (1986). 60

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J. Ellis, D.V. Nanopoulos and M. Quir'os, Phys. Lett. B174 (1986) 176.

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