<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mrow><mml:mi mathvariant="script">F</mml:mi></mml:mrow><mml:mi>t</mml:mi></mml:mrow></mml:math>values of the<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mi>T</mml:mi><mml:mo>=</mml:mo><mml:mn>1</mml:mn><mml:mo>/</mml:mo><mml:mn>2</mml:mn></mml:mrow></mml:math>mirror β transitions

Severijns, N.; Tandecki, M.; Phalet, T.; Towner, I. S.

doi:10.1103/physrevc.78.055501

Cited by 120 publications

(285 citation statements)

References 36 publications

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“…The fit function contained a constant background plus four exponentials corresponding to the decays of 37 K and the main contaminants 35 [8]. The intensity of the contaminants could not be fit sepa- rately because of the high correlations between them, so we fixed the relative normalization of the contaminants at the values measured in the MARS focal-plane detector (corrected for losses in the degraders), and allowed only the total amount of contaminant activity to vary relative to 37 K in the fitting procedure.…”

Section: Discussionmentioning

confidence: 99%

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Precision half-life measurement of theβ+decay ofK37

et al. 2014

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The half-life of 37 K has been measured to be 1.23651(94) s, a value nearly an order of magnitude more precise than the best previously reported. The β + decay of 37 K occurs mainly via a superallowed branch to the ground-state of its T = 1/2 mirror, 37 Ar. This transition has been used recently, together with similar transitions from four other nuclei, as an alternative test of CVC and method for determining V ud , but the precision of its f t value was limited by the relatively large half-life uncertainty. Our result corrects that situation. Another motivation for improving the f t value was to determine the standard-model prediction for the β-decay correlation parameters, which will be compared to those currently being measured by the Trinat collaboration at Triumf. The new f t value, 4605(8) s, is now limited in precision by the 97.99(14)% ground-state branching ratio.

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Section: Discussionmentioning

confidence: 99%

“…[7] and [8] by defining the corrected F t value for mirror nuclei which includes the variation due to the ratio of the Fermi to Gamow-Teller matrix elements. Specifically, the F t 0 value is defined as…”

Section: F T-valuementioning

confidence: 99%

Precision half-life measurement of theβ+decay ofK37

et al. 2014

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“…Transitions between the isobaric analogue states in mirror nuclei |T = 1/2, I, T z = −1/2 →|T = 1/2, I, T z = +1/2 offer an alternative way to extract the F t-values [48] and V ud [40,49]. Those transitions are mixed Fermi and Gamow-Teller, meaning that they are mediated by both the vector and axial-vector currents.…”

Section: Isb Corrections To the Fermi Matrix Elements In Mirror-smentioning

confidence: 99%

“…TABLE V. Results of calculations for |T = 1/2, I, Tz = −1/2 →|T = 1/2, I, Tz = +1/2 β-decays between mirror nuclei: theoretical spin and parity assignments; isospin-mixing coefficients in the parent and daughter nuclei; ISB corrections calculated in this work (asterisks denote results obtained within unrestricted-symmetry calculations); ISB corrections of Ref. [48]; quadrupole equilibrium deformation parameters in the parent nuclei; and theoretical and experimental Q β values. The calculations also indicate an appreciable impact of the signature-symmetry constraint on δ V C , in particular, in the pf -shell nuclei with A = 45, 47, and 49.…”

Section: Isb Corrections To the Fermi Matrix Elements In Mirror-smentioning

confidence: 99%

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Isospin-breaking corrections to superallowed Fermiβdecay in isospin- and angular-momentum-projected nuclear density functional theory

et al. 2012

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Background: The superallowed β-decay rates provide stringent constraints on physics beyond the Standard Model of particle physics. To extract crucial information about the electroweak force, small isospin-breaking corrections to the Fermi matrix element of superallowed transitions must be applied.Purpose: We perform systematic calculations of isospin-breaking corrections to superallowed β-decays and estimate theoretical uncertainties related to the basis truncation, time-odd polarization effects related to the intrinsic symmetry of the underlying Slater determinants, and to the functional parametrization. Methods:We use the self-consistent isospin-and angular-momentum-projected nuclear density functional theory employing two density functionals derived from the density independent Skyrme interaction. Pairing correlations are ignored. Our framework can simultaneously describe various effects that impact matrix elements of the Fermi decay: symmetry breaking, configuration mixing, and long-range Coulomb polarization. Results:The isospin-breaking corrections to the I = 0 + , T = 1 → I = 0 + , T = 1 pure Fermi transitions are computed for nuclei from A=10 to A=98 and, for the first time, to the Fermi branch of the I, T = 1/2 → I, T = 1/2 transitions in mirror nuclei from A=11 to A=49. We carefully analyze various model assumptions impacting theoretical uncertainties of our calculations and provide theoretical error bars on our predictions. Conclusions:The overall agreement with empirical isospin-breaking corrections is very satisfactory. Using computed isospin-breaking corrections we show that the unitarity of the CKM matrix is satisfied with a precision better than 0.1%.

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Precision measurements in nuclear ‐decay with LPCTrap

et al. 2013

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The experimental achievements and the current program with the LPCTrap device installed at the LIRAT beam line of the SPIRAL1-GANIL facility are presented. The device is dedicated to the study of the weak interaction at low energy by means of precise measurements of the β−ν angular correlation parameter. Technical aspects as well as the main results are reviewed. The future program with new available beams is briefly discussed. The β−ν angular correlationThe structure of the weak interaction remains an important topic in the area of fundamental interaction physics. In particular, at low energies, there are nowadays ambitious experimental programs to search for "exotic" currents beyond the V-A theory [1,2]. Such studies have recently made significant progress with the advent of improved trapping techniques [3,4]. These sophisticated setups allow the production of β-decay sources almost at rest and confined in small volumes that can be surrounded by suitable detectors [5,6]. We describe here the achievements made with the LPCTrap setup installed at GANIL 1 . The experimental program is dedicated to precision measurements of the β−ν angular correlation parameter.From a theoretical point of view, the generalization of Fermi's theory leads to consideration of five different Lorentz invariant contributions in the transition amplitude describing nuclear beta decay, which are referred to as scalar (S), vector (V), tensor (T), axial-vector (A) and pseudoscalar (P). The search for S and T exotic contributions can be performed through a precise measurement of the β−ν angular correlation parameter, a βν . For allowed transitions and nonoriented nuclei, this parameter can be directly inferred from an events distribution linked to the angular correlation between the leptons [7]. GANIL: Grand Accélérateur National d'Ions LourdsSince neutrinos are difficult to detect, a sensitive observable for a β−ν angular correlation measurement is a kinematic parameter of the recoiling daughter nucleus. If the β particles and the recoil ions are detected in coincidence and the relative time of flight (ToF) is measured between the two particles, the expected distribution of events in the electron energy and recoil ion time of flight, t, is for all solid angles detected:where T e , E e and r(t) denote the kinetic and total energies of the β particle and the recoil ion momentum, respectively. Q is the energy available in the transition, K is a constant and F(± Z, E e ) is the Fermi function (β − and β + decays). The parameter a βν and the Fierz interference term b depend on the coupling constants, C i and C i (i = S, V, T, A), associated to the different contributions [7]:

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Ftvalues of theT=1/2mirror β transitions

Cited by 120 publications

References 36 publications

Precision half-life measurement of theβ+decay ofK37

Precision half-life measurement of theβ+decay ofK37

Isospin-breaking corrections to superallowed Fermiβdecay in isospin- and angular-momentum-projected nuclear density functional theory

Precision measurements in nuclear ‐decay with LPCTrap

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