Effect of bound dineutrons upon big bang nucleosynthesis

Kneller, James P.; McLaughlin, G. C.

doi:10.1103/physrevd.70.043512

Cited by 25 publications

(24 citation statements)

References 74 publications

(138 reference statements)

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“…), and of the way the world would be once those thresholds are crossed (e.g., how does a neutron-stable world behave? ), as the masses are tuned via variations in w. The changes in w contemplated here-which lead to altogether qualitatively different worlds-are larger than those studied in the context of observational constraints on time or space variations in w or other Standard Model parameters in our universe (e.g., [21,22,23,24,25,26,27,28,29,30,31].) In addition this paper is does not actually apply anthropic reasoning or thoroughly explore the parameter space of possible worlds (e.g., [32]); it just explores the nuclear astrophysics of varying w with other parameters held fixed.…”

Section: Introductionmentioning

confidence: 93%

“…[38,39] We do not know for example at what value of w (if any) the dineutron becomes stable, or what its binding energy or decay time to a deuteron would be. [27] (It is unbound in our world by only 70keV). Even so, the state of QCD modeling for single isolated baryons is now good enough to estimate the neutron-proton mass difference and therefore the threshold of neutron stability.…”

Section: Nuclear Astrophysics With W <mentioning

confidence: 99%

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Nuclear astrophysics of worlds in the string landscape

Hogan

2006

Phys. Rev. D

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Motivated by landscape models in string theory, cosmic nuclear evolution is analyzed allowing the Standard Model Higgs expectation value w to take values different from that in our world (w ≡ 1), while holding the Yukawa couplings fixed. Thresholds are estimated, and astrophysical consequences are described, for several sensitive dependences of nuclear behavior on w. The dependence of the neutron-proton mass difference on w is estimated based on recent calculations of strong isospin symmetry breaking, and is used to derive the threshold of neutron-stable worlds, w ≈ 0.6 ± 0.2. The effect of a stable neutron on nuclear evolution in the Big Bang and stars is shown to lead to radical differences from our world, such as a predominance of heavy r-process and s-process nuclei and a lack of normal galaxies, stars and planets. Rough estimates are reviewed of w thresholds for deuteron stability and the pp and pep reactions dominant in many stars. A simple model of nuclear resonances is used to estimate the w dependence of overall carbon and oxygen production during normal stellar nucleosynthesis; carbon production is estimated to change by a fraction ≈ 15(1 − w). Radical changes in astrophysical behavior seem to require changes in w of more than a few percent, even for the most sensitive phenomena.

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Section: Introductionmentioning

confidence: 93%

Section: Nuclear Astrophysics With W <mentioning

confidence: 99%

Nuclear astrophysics of worlds in the string landscape

Hogan

2006

Phys. Rev. D

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“…Therein the emission of two correlated neutrons with low relative momentum from the excited 10 Be nucleus was observed and satisfactorily described in an effective three-body model: 8 Be gs + n + n. The only differences with respect to Ref. [1] are the way of production (n+ 9 Be → n +n+ 8 Be gs ) and somewhat higher excitation energy (E ex = 16 MeV).…”

Section: Introductionmentioning

confidence: 87%

“…It has been checked (Ref. [9]) that such states would affect the big bang nucleosynthesis only, if the binding energy were greater than 3 MeV. However, such strong binding is hardly expected given the current empirical evidence.…”

Section: Neutral Nuclei-hints From Theory?mentioning

confidence: 99%

A Method for Unambiguous Detection of a Hypothetical Bound Two-Neutron System

Bodek

2013

Few-Body Syst

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An experiment is proposed aiming at the unambiguous detection of mass A = 2 neutral particles via elastic scattering and neutron exchange reactions on protons in a plastic scintillating fibre detector. Dineutrons would be produced in ordinary π − absorption at rest on 3 He together with tagging protons. The basic advantages of the proposed process are the strict collinearity and opposite, and constant momenta of hypothetical di-neutrons and recoiling particles in the LAB reference frame. Moreover, the detection cross sections ( 2 n + p → p + 2 n; 2 n + p → d + n) are calculable with three-nucleon codes based on 1 a nn dependent nn interactions.

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“…The effects of a bound dineutron on BBN were studied in [46], where it was found that the final abundances were essentially unaffected as long as the dineutron binding energy remained smaller than B D . An effective field theory analysis may also be applied to the binding of the dineutron, which lies in a different channel from the deuteron [65].…”

Section: Stability Of Dineutron and 8 Bementioning

confidence: 99%

Primordial nucleosynthesis as a probe of fundamental physics parameters

2007

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We analyze the effect of variation of fundamental couplings and mass scales on primordial nucleosynthesis in a systematic way. The first step establishes the response of primordial element abundances to the variation of a large number of nuclear physics parameters, including nuclear binding energies. We find a strong influence of the n − p mass difference (for the 4 He abundance), of the nucleon mass (for deuterium) and of A = 3, 4, 7 binding energies (for 3 He, 6 Li and 7 Li). A second step relates the nuclear parameters to the parameters of the Standard Model of particle physics. The deuterium, and, above all, 7 Li abundances depend strongly on the average light quark massm ≡ (m u + m d )/2. We calculate the behaviour of abundances when variations of fundamental parameters obey relations arising from grand unification. We also discuss the possibility of a substantial shift in the lithium abundance while the deuterium and 4 He abundances are only weakly affected.

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Effect of bound dineutrons upon big bang nucleosynthesis

Cited by 25 publications

References 74 publications

Nuclear astrophysics of worlds in the string landscape

Nuclear astrophysics of worlds in the string landscape

A Method for Unambiguous Detection of a Hypothetical Bound Two-Neutron System

Primordial nucleosynthesis as a probe of fundamental physics parameters

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