相关论文: The Angular Correlations in the $e^+e^-$ Decay of …
Measurements of the $^2$H($^{16}$C,$^{16}$C$^{*}$$\rightarrow^4$He+$^{12}$Be or $^6$He+$^{10}$Be)$^2$H inelastic excitation and cluster-decay reactions have been carried out at a beam energy of about 23.5 MeV/u. A specially designed…
Electron-positron angular correlations were measured for the isovector magnetic dipole 17.6 MeV state ($J^\pi=1^+$, $T=1$) $\rightarrow$ ground state ($J^\pi=0^+$, $T=0$) and the isoscalar magnetic dipole 18.15 MeV ($J^\pi=1^+$, $T=0$)…
In this paper we report on a systematic search for a neutral boson in the mass range between 5 and 15 MeV/c$^{2}$ in the decay of highly excited nuclei. Its signature is found a deviation in the angular correlation of the $e^+e^-$ pairs…
The QCD axion remains experimentally viable in the mass range of O(10 MeV) if (i) it couples predominantly to the first generation of SM fermions; (ii) it decays to $e^+ e^-$ with a short lifetime $\tau_a\lesssim 10^{-13}\,$s; and (iii) it…
The improved results on a direct search for a new X(16.7 MeV) boson which could explain the anomalous excess of $e^+e^-$ pairs observed in the excited 8Be nucleus decays ("Berillium anomaly") are reported. Due to its coupling to electrons,…
In the presence of an electric dipole coupling of $t \bar t$ to a photon, and an analogous ``weak" dipole coupling to the $Z$, $CP$ violation in the process $e^+e^- \rightarrow t \bar t$ leads to the polarization of the top and anti-top.…
A cluster-transfer experiment $^9$Be($^9$Be,$^{14}$C$^*\rightarrow\alpha$+$^{10}$Be)$\alpha$ was carried out using an incident beam energy of 45 MeV. This reaction channel has a large $Q$-value that favors populating the high-lying states…
An exclusive measurement of the Coulomb breakup of 8B into 7Be+p at 254 A MeV allowed to study the angular correlations of the breakup particles. These correlations demonstrate clearly that E1 multipolarity dominates and that E2…
We give a precision analysis of the correlation coefficients of the electron-energy spectrum and angular distribution of the beta decay and radiative beta decay of the neutron with polarized neutron and electron to order 10^(-3). The…
The anomaly found in the excited $^8\text{Be}$ nuclear transition to its ground state is attributed to a spin-1 gauge boson $X(16.7)$. To hunt for this boson, we propose two traps: $e^+e^-\to X\gamma$ and $J/\psi\to X\gamma$, both following…
The 12B excitation energy spectrum has been obtained from coincidence measurements of the 9Be+7Li -> 2alpha+8Li reaction at E{0}=52 MeV. The decay of the states at excitations between 10 and 16 Mev into alpha$+8Li has been observed for the…
The unbound nucleus $^{7}$He was recently studied in the $^2$H($^{6}$He,$^1$H)$^{7}$He reaction at 29 $A\,$MeV beam energy in Ref.[M.S. Golovkov et al., Phys. Rev. C 109, L061602 (2024)]. The excitation spectrum of $^{7}$He was measured up…
The $B$(E1;$1/2^+\to1/2^-$) strength for $^{11}$Be has been extracted from intermediate energy Coulomb excitation measurements, over a range of beam energies using a new reaction model, the extended continuum discretized coupled channels…
Using the CLEO detector at the Cornell Electron Storage Ring, we have studied the distribution of kinematic variables in the decay Lambda_c^+ -> Lambda e^+ nu_e. By performing a four-dimensional maximum likelihood fit, we determine the form…
The first measurement of two-particle angular correlations for charged particles produced in $e^+e^-$ annihilation up to $\sqrt{s}$ = 209 GeV is presented. Hadronic $e^+e^-$ data, archived at center-of-mass energies ranging from 91 to 209…
A full calculation of lepton-pair angular characteristics is carried out for $e^+e^-$ pairs created in $pp$, $pn$ and $pd$ collisions at intermediate energies. It is demonstrated that the proposed new observable, the dilepton decay…
We study the branching ratios of the allowed and forbidden radiative transitions among the first few (9) fine structure levels of O VI using relativistic coupled cluster theory. We find irregular patterns for a number of transitions with in…
Isovector and isoscalar dipole excitations in $^9$Be and $^{10}$Be are investigated in the framework of antisymmetrized molecular dynamics, in which angular-momentum and parity projections are performed. In the present method, 1p-1h…
The resonance region of $^{11}$B covering excitation energies from 8.4 MeV to 13.6 MeV was investigated with the $(d,p)$ reaction performed on an enriched $^{10}$B target at the Florida State University Super-Enge Split-Pole Spectrograph of…
We have searched for the rare decay of the eta meson $\eta \to e^{+}e^{-}$ using the CLEO II detector. The $\eta$'s were produced in $e^{+}e^{-}$ collisions with 10 GeV center-of-mass energy at the Cornell Electron Storage Ring (CESR). We…