Cosmological constant and vacuum energy: old and new ideas

By J. Solà. 2013

326 citations recorded by the source corpus.

The cosmological constant (CC) term in Einstein's equations, Λ, was first associated to the idea of vacuum energy density. Notwithstanding, it is well-known that there is a huge, in fact appalling, discrepancy between the theoretical prediction and the observed value picked from the modern cosmological data. This is the famous, and extremely difficult, "CC problem". Paradoxically, the recent observation at the CERN Large Hadron Collider of a Higgs-like particle, should actually be considered ambivalent: on the one hand it appears as a likely great triumph of particle physics, but on the other hand it wide opens Pandora's box of the cosmological uproar, for it may provide (alas!) the experimental certification of the existence of the electroweak (EW) vacuum energy, and thus of the intriguing reality of the CC problem. Even if only counting on this contribution to the inventory of vacuum energies in the universe, the discrepancy with the cosmologically observed value is already of 55 orders of magnitude. This is the (hitherto) "real" magnitude of the CC problem, rather than the (too often) brandished 123 ones from the upper (but fully unexplored!) ultrahigh energy scales. Such is the baffling situation after 96 years of introducing the Λ-term by Einstein. In the following I will briefly (and hopefully pedagogically) fly over some of the old and new ideas on the CC problem. Since, however, the Higgs boson just knocked our door and recalled us that the vacuum energy may be a fully tangible concept in real phenomenology, I will exclusively address the CC problem from the original notion of vacuum energy, and its possible "running" with the expansion of the universe, rather than venturing into the numberless attempts to replace the CC by the multifarious concept of dark energy.

Subfields: Astronomy and Astrophysics, Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/2a0ae69e97136e7c27f7aa0f3e68d8009b06dd7d

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Citations in the corpus

Possible signals of vacuum dynamics in the Universe (2017, background): “The last DVM under study is the so-called running vacuum model (RVM), which can be motivated in the context c© 0000 RAS, MNRAS 000, 000–000 of QFT in curved spacetime (cf. Solà 2013; Solà & GómezValent 2015, and references therein).”
Search for New Physics with Atoms and Molecules (2017, background): “sum of known contributions to vacuum energy in the universe and the cosmologically observed value is 55 orders of magnitude (Solà, 2013).”
Dynamical vacuum energy in the expanding Universe confronted with observations: a dedicated study (2014, methodology): “These can be well motivated within the context of quantum field theory (QFT) in curved spacetime since their structure is manifestly compatible with the general covariance of the effective action and can be linked to the notion of renormalization group.”