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UID:UW-Physics-Event-1559
DTSTART:20090618T210000Z
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DTSTAMP:20260409T130324Z
LAST-MODIFIED:20090610T161956Z
LOCATION:4274 Chamberlin
SUMMARY:Cosmic acceleration as the gravitational feedback of mass-vary
 ing dark matter\, NPAC (Nuclear/Particle/Astro/Cosmo) Forum\, Andre Fu
 zfa\, GAMASCO\, University of Namur (FUNDP)\; Louvain U\; Paris Observ
 atory\;
DESCRIPTION:Coupling dark matter (DM) to dark energy (DE) is one of th
 e most promising way to build a unified description of the invisible s
 ector of cosmology. It also glimpses beyond the concordance model LCDM
  in which DM and DE are assumed physically unrelated. However\, such D
 M-DE couplings make the mass of the DM particles varying\, therefore b
 reaking the universality of free fall (Galileo's equivalence principle
 ). Doing so\, the strong equivalence principle\, stating the universal
 ity of gravitational binding energy\, does not hold anymore\, particul
 arly where DM is profuse like in the large-scale universe. Mass-varyin
 g DM therefore induces modifications of gravity. This gravitational fe
 edback on ordinary matter can explain cosmic acceleration\, which is t
 hen interpreted as the observable signature of the violation of the eq
 uivalence principle on cosmological scales. To embrace the various phy
 sics of DM-induced violation of the equivalence principle\, we have de
 velopped a generalisation of Brans-Dicke tensor-scalar theories of gra
 vitation\, dubbed the Abnormally Weighting Energy (AWE) Hypothesis. In
  this approach\, the variation of the inertial mass of DM particles in
 duces a running of the gravitational coupling strength on cosmological
  scales that is observable in the late-time cosmic acceleration. Besid
 es of describing both DM and DE\, the AWE hypothesis allows measuring 
 the density paramters of baryons and dark matter from the Hubble diagr
 am *alone*\, and its predictions are consistent with the independent c
 osmological tests of Cosmic Microwave Background (CMB) and Big Bang Nu
 cleosynthesis (BBN). This interpretation also shed new light on the co
 incidence problem. We will end this seminar by showing how this mechan
 ism could interestingly be applied to the physics of neutrino mass gen
 eration and mass-varying neutrinos by turning the spontaneous symmetry
  breaking of lepton number symmetry into a gravitational symmetry brea
 king.
URL:https://www.physics.wisc.edu/events/?id=1559
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