Research output: Contribution to Journal/Magazine › Journal article › peer-review
Research output: Contribution to Journal/Magazine › Journal article › peer-review
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TY - JOUR
T1 - Dynamical cosmological constant from a very recent phase transition
AU - McDonald, John
PY - 2001/1/25
Y1 - 2001/1/25
N2 - Observation indicates that the expansion of the Universe is accelerating and favours a dynamical cosmological constant, Λ(t). We consider the possibility that this is due to a scalar field which has undergone a very recent phase transition. We study a simple class of model, corresponding to a φ4 potential with a time-dependent mass squared term. For the models considered the phase transition occurs at a red shift z⩽1.2. The evolution of the equation of state ωφ and energy density ρφ with time is distinct from existing dynamical Λ models based on slowly rolling fields, with ωφ and ρφ rapidly changing in a characteristic way following the transition. The φ energy density is composed of a time-dependent vacuum energy and coherently oscillating condensate component with a negative pressure. The condensate component will typically collapse to form non-topological soliton lumps, ‘φ-axitons’, which smoothly populate the Universe.
AB - Observation indicates that the expansion of the Universe is accelerating and favours a dynamical cosmological constant, Λ(t). We consider the possibility that this is due to a scalar field which has undergone a very recent phase transition. We study a simple class of model, corresponding to a φ4 potential with a time-dependent mass squared term. For the models considered the phase transition occurs at a red shift z⩽1.2. The evolution of the equation of state ωφ and energy density ρφ with time is distinct from existing dynamical Λ models based on slowly rolling fields, with ωφ and ρφ rapidly changing in a characteristic way following the transition. The φ energy density is composed of a time-dependent vacuum energy and coherently oscillating condensate component with a negative pressure. The condensate component will typically collapse to form non-topological soliton lumps, ‘φ-axitons’, which smoothly populate the Universe.
U2 - 10.1016/S0370-2693(00)01389-7
DO - 10.1016/S0370-2693(00)01389-7
M3 - Journal article
VL - 498
SP - 263
EP - 271
JO - Physics Letters B
JF - Physics Letters B
SN - 0370-2693
IS - 3-4
ER -