Big Bang Nucleosynthesis as a Probe of New Physics

Pospelov, Maxim; Pradler, Josef

doi:10.1146/annurev.nucl.012809.104521

Cited by 223 publications

(263 citation statements)

References 113 publications

(280 reference statements)

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“…Assuming that observations will confirm a somewhat higher 6 Li abundance with respect to the computed CDM ( Lambda Cold Dark Matter ) model value, the only remaining possibilities to explain the discrepancy are very special astrophysical processes like stellar flare in-situ lithium production [41] . Other possibilities are unknown physical processes or new physics scenarios [42][43][44][45] .…”

Section: Discussionmentioning

confidence: 99%

Big Bang 6 Li nucleosynthesis studied deep underground (LUNA collaboration)

Trezzi

Anders

Aliotta

et al. 2017

Astroparticle Physics

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a b s t r a c tThe correct prediction of the abundances of the light nuclides produced during the epoch of Big Bang Nucleosynthesis (BBN) is one of the main topics of modern cosmology. For many of the nuclear reactions that are relevant for this epoch, direct experimental cross section data are available, ushering the so-called "age of precision". The present work addresses an exception to this current status: the 2 H( α, γ ) 6 Li reaction that controls 6 Li production in the Big Bang. Recent controversial observations of 6 Li in metal-poor stars have heightened the interest in understanding primordial 6 Li production. If confirmed, these observations would lead to a second cosmological lithium problem, in addition to the well-known 7 Li problem. In the present work, the direct experimental cross section data on 2 H( α, γ ) 6 Li in the BBN energy range are reported. The measurement has been performed deep underground at the LUNA (Laboratory for Underground Nuclear Astrophysics) 400 kV accelerator in the Laboratori Nazionali del Gran Sasso, Italy. The cross section has been directly measured at the energies of interest for Big Bang Nucleosynthesis for the first time, at E cm = 80, 93, 120, and 133 keV. Based on the new data, the 2 H( α, γ ) 6 Li thermonuclear reaction rate has been derived. Our rate is even lower than previously reported, thus increasing the discrepancy between predicted Big Bang 6 Li abundance and the amount of primordial 6 Li inferred from observations.

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Section: Discussionmentioning

confidence: 99%

Big Bang 6 Li nucleosynthesis studied deep underground (LUNA collaboration)

Trezzi

Anders

Aliotta

et al. 2017

Astroparticle Physics

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“…There are cosmological upper bounds on stable gravitinos (see e.g. [59][60][61][62] and references therein). From CMB measurements one gets m 3/2 ≤ 4.7 eV [60] and from primordial nucleosintesis m 3/2 ≤ 16 eV.…”

Section: Jhep11(2017)066mentioning

confidence: 99%

“…Details on bounds of dark radiation depend sensitively on how and when the particle decoupled and hence need not apply to the light degrees of freedom here considered (see e.g. [61,62]). …”

Section: Jhep11(2017)066mentioning

confidence: 99%

Constraining neutrino masses, the cosmological constant and BSM physics from the weak gravity conjecture

Ibáñez

Lozano²,

Valenzuela

2017

J. High Energ. Phys.

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It is known that there are AdS vacua obtained from compactifying the SM to 2 or 3 dimensions. The existence of such vacua depends on the value of neutrino masses through the Casimir effect. Using the Weak Gravity Conjecture, it has been recently argued by Ooguri and Vafa that such vacua are incompatible with the SM embedding into a consistent theory of quantum gravity. We study the limits obtained for both the cosmological constant Λ 4 and neutrino masses from the absence of such dangerous 3D and 2D SM AdS vacua. One interesting implication is that Λ 4 is bounded to be larger than a scale of order m 4 ν , as observed experimentally. Interestingly, this is the first argument implying a non-vanishing Λ 4 only on the basis of particle physics, with no cosmological input. Conversely, the observed Λ 4 implies strong constraints on neutrino masses in the SM and also for some BSM extensions including extra Weyl or Dirac spinors, gravitinos and axions. The upper bounds obtained for neutrino masses imply (for fixed neutrino Yukawa and Λ 4 ) the existence of upper bounds on the EW scale. In the case of massive Majorana neutrinos with a see-saw mechanism associated to a large scale M 10 10−14 GeV and Y ν 1 10 −3 , one obtains that the EW scale cannot exceed M EW 10 2 − 10 4 GeV. From this point of view, the delicate fine-tuning required to get a small EW scale would be a mirage, since parameters yielding higher EW scales would be in the swampland and would not count as possible consistent theories. This would bring a new perspective into the issue of the EW hierarchy.

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“…Such proposed solutions include (but are by no means restricted to) invoking WIMPS and SUSY [10], invoking Axions [11], varying fundamental constants [12], or using non-standard cosmologies such as allowing the universe to be inhomogeneous at Hubble scales [13]. These solutions are necessarily somewhat speculative.…”

Section: New Physics Solutionsmentioning

confidence: 99%

Nuclear Physics Solutions to the Primordial Lithium Problem

Cook

Luong

Williams

2012

EPJ Web of Conferences

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Abstract. The primordial lithium problem is one of the major outstanding issues in the standard model of the Big Bang. Measurements of the baryon to photon ratio in the cosmic microwave background constrain model predictions, giving abundances of 7 Li two to four times larger than observed via spectroscopic measurements of metal-poor stars. In an attempt to reconcile this discrepancy, significant effort has been directed at measuring reaction cross sections of light nuclei at astrophysically relevant energies. However, there remain reaction cross sections with large uncertainties, and some that have not yet been measured. Particularly relevant are those involving the destruction of 7 Be, a progenitor of 7 Li. Key issues that can be improved by nuclear physics input will be highlighted, and the applicability of detectors and event reconstruction techniques recently developed at the ANU will be discussed.

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Big Bang Nucleosynthesis as a Probe of New Physics

Cited by 223 publications

References 113 publications

Big Bang 6 Li nucleosynthesis studied deep underground (LUNA collaboration)

Big Bang 6 Li nucleosynthesis studied deep underground (LUNA collaboration)

Constraining neutrino masses, the cosmological constant and BSM physics from the weak gravity conjecture

Nuclear Physics Solutions to the Primordial Lithium Problem

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