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All sourcesNASA NTRSDOE OSTI
DOE OSTI2018

Weak Decays

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Wojcicki, S.↗
DOE OSTI2018

Weak Decays at PEP

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Yelton, J.↗
NASA NTRS1970

Decay of weak turbulence

Decay time of low Reynolds number weak turbulence generated by single and multistage grids, considering three dimensional energy spectrum

Huang, T. T.↗
DOE OSTI2019

Kaon Photoproduction and the Λ Decay Parameter α –

The weak decay parameter $\alpha_-$ of the $\Lambda$ is an important quantity for the extraction of polarization observables in various experiments. Moreover, in combination with $\alpha_+$ from $\bar\Lambda$ decay it provides a measure for matter-antimatter asymmetry. The weak decay parameter also affects the decay parameters of the $\Xi$ and $\Omega$ baryons and, in general, any quantity in which the polarization of the $\Lambda$ is relevant. The recently reported value by the BESIII collaboration of $0.750(9)(4)$ is significantly larger than the previous PDG value of $0.642(13)$ that had been accepted and used for over 40 years. In this work we make an independent estimate of $\alpha_-$, using an extensive set of polarization data measured in kaon photoproduction in the baryon resonance region and constraints set by spin algebra. The obtained value is 0.721(6)(5). The result is corroborated by multiple statistical tests as well as a modern phenomenological model, showing that our new value yields the best description of the data in question. Furthermore, our analysis supports the new BESIII finding that $\alpha_-$ is significantly larger than the previous PDG value. Any experimental quantity relying on the value of $\alpha_-$ should therefore be re-considered.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2023

First search for the weak radiative decays Λ$^+_c$ → Σ + γ and Ξ$^0_c$ → Ξ 0 γ

We present the first search for the weak radiative decays Λ$^+_c$ → Σ + γ and Ξ$^0_c$ → Ξ 0 γ using a data sample of 980 fb -1 collected by the Belle detector operating at the KEKB asymmetric-energy e + e - collider. There are no evident Λ$^+_c$ → Σ + γ or Ξ$^0_c$ → Ξ 0 γ signals. Taking the decays Λ$^+_c$ → pK - π + and Ξ$^0_c$ → Ξ - π + as normalization channels, the upper limits at 90% credibility level on the ratios of branching fractions $\mathcal{B}$(Λ$^+_c$ → Σ + γ)/$\mathcal{B}$(Λ$^+_c$ → pK - π + ) < 4.0 x 10 -3 and $\mathcal{B}$(Ξ$^0_c$ → Ξ 0 γ)/$\mathcal{B}$(Ξ$^0_c$ → Ξ - π + ) < 1.2 x 10 -2 are determined. We obtain the upper limits at 90% credibility level on the absolute branching fractions $\mathcal{B}$(Λ$^+_c$ → Σ + γ) < 2.6 x 10 -4 and $\mathcal{B}$(Ξ$^0_c$ → Ξ 0 γ) < 1.8 x 10 -4 .

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2016

Probing the Goldstone equivalence theorem in heavy weak doublet decays

We explore here the decays from heavy Higgsino-like weak doublets into Z , h bosons and missing particles. When pair-produced at the LHC, the subsequent Z , h → ℓ ℓ , b b ¯ decays in the doublet decay cascade can yield 4 ℓ , 2 ℓ 2 b and 4 b + E T + j ( s ) final states. Mutual observation of any two of these channels would provide information on the associated doublets’ decay branching fractions into a Z or h , thereby probing the Goldstone equivalence relation, shedding additional light on the Higgs sector of beyond the Standard Model theories and facilitating the discrimination of various contending models, in turn. We compare the Z / h decay ratio expected in the minimal supersymmetric model, the next-to-minimal supersymmetric model (NMSSM)and a minimal singlet-doublet dark matter model. Furthermore, we conduct a full Monte Carlo analysis of the prospects for detecting the targeted final states during 14 TeV running of the LHC in the context of a representative NMSSM benchmark model.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2022

On the stability of the open-string QED neutron and dark matter

We study the stability of a hypothetical QED neutron, which consists of a color-singlet system of two d quarks and a u quark interacting with the QED interaction. As a quark cannot be isolated, the intrinsic motion of the three quarks in the lowest-energy state may lie predominantly in 1 + 1 dimensions, as in a d-u-d open string. The attractive d-u and u-d QED interactions may overcome the weaker repulsive d-d QED interaction to bind the three quarks together. We examine the QED neutron in a phenomenological three-body problem in 1 + 1 dimensions with an effective interaction extracted from Schwinger’s exact QED solution in 1 + 1 dimensions. The phenomenological model in a variational calculation yields a stable QED neutron at 44.5 MeV. The analogous QED proton with two u quarks and a d quark has been found to be too repulsive to be stable and does not have a bound or continuum state, onto which the QED neutron can decay via the weak interaction. Consequently, the QED neutron is stable against the weak decay, has a long lifetime, and is in fact a QED dark neutron. It may be produced following the deconfinement-to-confinement phase transition of the quark gluon plasma in high-energy heavy-ion collisions. Because of the long lifetime of the QED dark neutron, self-gravitating assemblies of QED dark neutrons or dark antineutrons may be good candidates for a part of the primordial dark matter produced during the phase transition of the quark gluon plasma in the evolution of the early Universe.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗