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Register a new userSearch for the Radiative Capture d+d->^4He+gamma Reaction from the ddmu Muonic Molecule State
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L. N. Bogdanova
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A search for the muon catalyzed fusion reaction dd --> ^4He +gamma in the ddmu muonic molecule was performed using the experimental mu CF installation TRITON and NaI(Tl) detectors for gamma-quanta. The high pressure target filled with deuterium at temperatures from 85 K to 800 K was exposed to the negative muon beam of the JINR phasotron to detect gamma-quanta with energy 23.8 MeV. The first experimental estimation for the yield of the radiative deuteron capture from the ddmu state J=1 was obtained at the level n_{gamma}leq 2times 10^{-5} per one fusion.
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We report a search for d^* dibaryon production by double-radiative capture on pionic deuterium. The experiment was conducted at the TRIUMF cyclotron using the RMC cylindrical pair spectrometer, and detected gamma-ray coincidences following pion stops in liquid deuterium. We found no evidence for narrow dibaryons, and obtained a branching ratio upper limit, BR < 6.7 times 10^{-6} (90% C.L.), for narrow d^* production in the mass range from 1920 to 1980 MeV. Replaced with Physics Letter B accepted version and corrected normalization.
We report the first observation of the charge symmetry breaking d + d -> 4He + pi0 reaction near threshold at the Indiana University Cyclotron Facility. Kinematic reconstruction permitted the separation of 4He + pi0 events from double radiative capture 4He + gamma + gamma events. We measured total cross sections for neutron pion production of 12.7 +- 2.2 pb at 228.5 MeV and 15.1 +- 3.1 pb at 231.8 MeV. The uncertainty is dominated by statistical errors.
To investigate the interaction between the nucleon $N$ and nucleon resonance $N(1535)1/2^-$, the $eta d$ threshold structure, connected to the isoscalar $S$-wave $N$-$N(1535)1/2^-$ system, has been experimentally studied in the $gamma{d}${$to$}$pi^0eta{d}$ reaction at incident photon energies ranging from the reaction threshold to 1.15 GeV. A strong enhancement is observed near the $eta d$ threshold over the three-body phase-space contribution in the $eta d$ invariant-mass distribution. An analysis incorporating the known isovector resonance $mathcal{D}_{12}$ with a spin-parity of $2^+$ in the $pi^0d$ channel has revealed the existence of a narrow isoscalar resonance-like structure $mathcal{D}_{eta d}$ with $1^-$ in the $eta d$ system. The Breit-Wigner mass of $mathcal{D}_{eta d}$ is found to be $2.425^{-0.006}_{+0.003}$ GeV, located just close to the $eta d$ threshold, and the width is $0.034_{-0.003}^{+0.004}$ GeV. The $mathcal{D}_{eta d}$ would be a predicted isoscalar $1^-$ $eta NN$ bound state from the $eta NN$ and $pi NN$ coupled-channel calculation, or $eta d$ virtual state owing to strong $eta d$ attraction.
We have observed an intense high-energy component in an inclusive $^4$He(stopped $K^-$, $d$) spectrum. For back-to-back $Lambda d$ pairs a prominent event cluster has been found just below the $m_{^4textrm{He}}+m_{K^-}-m_{n}$ mass threshold in the $Lambda d$ invariant mass spectrum of $Lambda dn$ events, which is evidence for a three-nucleon absorption process of $K^-$ in $^4$He. In addition, an appreciable strength is revealed below $sim$3220 MeV/$c^2$. Well separated $Sigma^0 dn$ events show a peak similar to the case of $Lambda dn$.
Using an electron-positron collision data sample of 2.93 fb$^{-1}$ collected at a center-of-mass energy of $sqrt{s}=3.773$ GeV with the BESIII detector, we present the first search for the radiative leptonic decay $D^{+} rightarrow gamma e^{+}{ u}_{e}$. The analysis is performed with a double tag method. We do not observe a significant $D^{+} rightarrow gamma e^{+}{ u}_{e}$ signal, and obtain an upper limit on the branching fraction of $D^{+} rightarrow gamma e^{+}{ u}_{e}$ decay with the energy of radiative photon larger than 10 MeV of $3.0times10^{-5}$ at the 90% confidence level.
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