Neutron-proton mass difference in nuclear matter

The electromagnetic transition between the almost degenerate 5/2 + and 3/2 + states in 229 Th is deemed to be very sensitive to potential changes in the fine structure constant α. State of the art Hartree-Fock and Hartree-Fock-Bogoliubov calculations are performed to compute the difference in Coulomb energies of the two states which determines the amplification of variations in α into variations of the transition frequency. The kinetic energies are also calculated which reflect a possible variation in the nucleon or quark masses. A generalized Hellmann-Feynman theorem is proved including the use of density-matrix functionals. As the two states differ mainly in the orbit occupied by the last unpaired neutron the Coulomb energy difference results from a change in the nuclear polarization of the proton distribution. This effect turns out to be rather small and to depend on the nuclear model, the amplification varies between about −4 × 10 4 and +4 × 10 4 . Therefore much more effort must be put into the improvement of the nuclear models before one can draw conclusions from a measured drift in the transition frequency on a temporal drift of fundamental constants. All calculations published so far do not reach the necessary fidelity.

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“…The dependence of the nucleon masses on α can be estimated from the paper by Meißner et al [25] (Eq. (36)).…”

Section: Amplificationmentioning

confidence: 99%

Nuclear structure of lowestTh229states and time-dependent fundamental constants

et al. 2009

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“…In this context we recently studied isospin-breaking effects in the baryonic sector of a medium-modified Skyrme model [35], by focusing on the single hadron properties in the nuclear environment rather than on the properties of the system as a whole. The approach predicted that the neutron-proton mass difference changes in an isospinsymmetric nuclear environment by a very small amount.…”

Section: Introductionmentioning

confidence: 99%

“…The Lagrangian of the present study is a generalization of the in-medium Skyrme-type Lagrangian of Ref. [35]. In addition to the strong isospin-breaking in the mesonic sector it explicitly takes into account the different influences of the isospin-asymmetric environment on the charged (π ± ) and neutral (π 0 ) pion fields via a builtin energy dependence in the s-wave pion-nucleon (π ± N) scattering lengths [37,38,39,40,41] and the p-wave optical potential [42].…”

Section: Introductionmentioning

confidence: 99%

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Neutron-proton mass difference in isospin-asymmetric nuclear matter

et al. 2007

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Abstract. Isospin-breaking effects in the baryonic sector are studied in the framework of a medium-modified Skyrme model. The neutron-proton mass difference in infinite, asymmetric nuclear matter is discussed. In order to describe the influence of the nuclear environment on the skyrmions, we include energy-dependent charged and neutral pion optical potentials in the s-and p-wave channels. The present approach predicts that the neutron-proton mass difference is mainly dictated by its strong part and that it strongly decreases in neutron matter.

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“…The results discussed in Sec. 5 show that ΔT n and ΔT p are of the same order as ΔV C so that the terms with the proton and neutron mass variations (see Meissner et al 7 ) can be neglected. Instead of measuring the nuclear transition frequency Berengut et al 8 proposed to look at atomic transitions that feel the isomeric field shift, which depends on the charge radii and quadruple moments of the two nuclear states.…”

Section: Amplificationmentioning

confidence: 96%

Variation of fundamental constants and ²²⁹Th

Feldmeier¹,

Литвинова²,

Flambaum³

et al. 2017

The Fourteenth Marcel Grossmann Meeting

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The first excited state of the nucleus 229 Th has an exceptionally small excitation energy of 7.8 eV, which is expected to be very sensitive to changes in the fine structure constant α. A small difference in the Coulomb energies of the two states, which both are of the order 10 9 eV, would amplify variations in α into large variations of the transition frequency. Hartree-Fock and Hartree-Fock-Bogoliubov calculations are performed to compute the Coulomb energies of the two states. The kinetic energies are also calculated which reflect a possible variation in the nucleon or quark masses or local Lorentz invariance violation.

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Neutron-proton mass difference in nuclear matter

Cited by 14 publications

References 41 publications

Nuclear structure of lowestTh229states and time-dependent fundamental constants

Nuclear structure of lowestTh229states and time-dependent fundamental constants

Neutron-proton mass difference in isospin-asymmetric nuclear matter

Variation of fundamental constants and ²²⁹Th

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Neutron-proton mass difference in nuclear matter

Cited by 14 publications

References 41 publications

Nuclear structure of lowestTh229states and time-dependent fundamental constants

Nuclear structure of lowestTh229states and time-dependent fundamental constants

Neutron-proton mass difference in isospin-asymmetric nuclear matter

Variation of fundamental constants and 229Th

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Variation of fundamental constants and ²²⁹Th