Is the Unitarity of the quark-mixing-CKM-matrix violated in neutron $\beta$-decay?

Abstract

We report on a new measurement of neutron $\beta$-decay asymmetry. From the result \linebreak $A_0$ = -0.1189(7), we derive the ratio of the axial vector to the vector coupling constant $\lambda$ = $g_A/g_V$ = -1.2739(19). When included in the world average for the neutron lifetime $\tau$ = 885.7(7)s, this gives the first element of the Cabibbo-Kobayashi-Maskawa (CKM) matrix $V_{ud}$. With this value and the Particle Data Group values for $V_{us}$ and $V_{ub}$, we find a deviation from the unitarity condition for the first row of the CKM matrix of $\Delta$ = 0.0083(28), which is 3.0 times the stated error.

Cited by in corpus (72)

• CP Violation and the CKM Matrix: Assessing the Impact of the Asymmetric B Factories
• Theory of Neutrinos: A White Paper
• Tests of the standard electroweak model in beta decay
• Measurement of the neutron lifetime using a gravitational trap and a low-temperature Fomblin coating
• Probing Novel Scalar and Tensor Interactions from (Ultra)Cold Neutrons to the LHC
• Flavor Physics in the Quark Sector
• The neutron and its role in cosmology and particle physics
• New physics searches in nuclear and neutron $\beta$ decay
• Measurement of the Weak Axial-Vector Coupling Constant in the Decay of Free Neutrons Using a Pulsed Cold Neutron Beam
• Semileptonic Hyperon Decays
• Precision Measurements and CKM Unitarity
• Determination of the Weak Axial Vector Coupling from a Measurement of the Beta-Asymmetry Parameter A in Neutron Beta Decay
• Neutron Lifetime and Axial Coupling Connection
• Calculated corrections to superallowed Fermi beta decay: New evaluation of the nuclear-structure-dependent terms
• Axial, Scalar and Tensor Charges of the Nucleon from 2+1+1-flavor Lattice QCD
• Isovector Charges of the Nucleon from 2+1+1-flavor Lattice QCD
• Low Energy Precision Test of Supersymmetry
• Determination of |Vud| from nuclear mirror transitions
• Big Bang Nucleosynthesis with a New Neutron Lifetime
• Standard Model $\mathcal{O}(\alpha )$ renormalization of $g_A$ and its impact on new physics searches
• Precision Measurement of the Neutron Beta-Decay Asymmetry
• New result for the neutron $\beta$-asymmetry parameter $A_0$ from UCNA
• Experiments in Fundamental Neutron Physics
• A clean, bright, and versatile source of neutron decay products
• V(us) Determination from Hyperon Semileptonic Decays
• Determination of the Axial-Vector Weak Coupling Constant with Ultracold Neutrons
• The Evaluation of V_{ud}, Experiment and Theory
• The NuTeV Anomaly, Lepton Universality, and Non-Universal Neutrino-Gauge Couplings
• The Puzzle of Neutron Lifetime
• Measurement of the Neutron Lifetime Using a Proton Trap
• Improved determination of the $\beta$-${\overline{\nu }}_e$ angular correlation coefficient $a$ in free neutron decay with the $a$SPECT spectrometer
• CP violation and the CKM matrix
• Measurement of the neutron $\beta$-asymmetry parameter $A_0$ with ultracold neutrons
• Search for a T-odd, P-even Triple Correlation in Neutron Decay
• Uncertainty quantification for proton-proton fusion in chiral effective field theory
• Quark Mixing, CKM Unitarity
• First Measurement of the Neutron $\beta$-Asymmetry with Ultracold Neutrons
• Radiative neutron beta-decay in effective field theory
• Inhomogeneous Big Bang Nucleosynthesis Revisited
• New precision measurements of free neutron beta decay with cold neutrons
• Framework for maximum likelihood analysis of neutron beta decay observables to resolve the limits of the V-A law
• Recent Developments in Precision Electroweak Physics
• Limits on tensor type weak currents from nuclear and neutron $\beta$~decays
• V_us From Hadronin Tau Decays
• On Continuum-State and Bound-State Beta Decay Rates of the Neutron
• A solenoidal electron spectrometer for a precision measurement of the neutron $\beta$-asymmetry with ultracold neutrons
• V_us From Hadronic Tau Decays
• R-parity violating supersymmetric contributions to the neutron beta decay
• CKM matrix and CP violation in B-mesons
• Unrecognized Backscattering in Low Energy Beta Spectroscopy
• Full One-Loop Radiative Corrections to the Asymmetry Parameter of Polarised Neutron Beta Decay
• Neutrino-deuteron reactions at solar neutrino energies
• Quantum levitation of nanoparticles seen with ultracold neutrons
• Study of levitating nanoparticles using ultracold neutrons
• Gauge Model of Quark-Lepton Nonuniversality
• Final results for the neutron $\beta$-asymmetry parameter $A_0$ from the UCNA experiment
• Testing the Unitarity of the CKM Matrix with a Space-Based Neutron Decay Experiment
• The magnetic shielding for the neutron decay spectrometer aSPECT
• Hexagonal SU(3) Unification and its Manifestation at the TeV Scale
• Conference Summary (5th Int. Conf. on Hyperons, Charm, and Beauty Hadrons)
• Measurement of the Axial-Vector Coupling Constant $g_A$ in Neutron Beta Decay
• The beta decay of Tz=-2 64Se and its descendants: the T=2 isobaric multiplet
• A novel technique of extracting UCN lifetimes from storage bottle measurements dominated by scattering losses
• Vus and neutron beta decay
• On V_ud determination from kaon decays
• New Physics Searches from Nucleon Matrix Elements in Lattice QCD
• Particles in finite volumes and a toy model of decaying neutrons
• Test of Symmetries with Neutrons and Nuclei
• Evidence against manifest right-handed currents in neutron beta decay
• Improved predictions of the standard model and the detection of new physics in neutron beta decay
• From primordial ${}^4$He abundance to the Higgs field
• Happy Birthday, Ultra-Cold Neutron!