Mon·Jun 25, 2018Monday·June 25, 2018

1. 01*

   Searching for states analogous to the 12C Hoyle state in heavier nuclei using the thick target inverse kinematics technique

   M. Barbui🇺🇸 · K. Hagel🇺🇸 · J. Gauthier🇺🇸 · S. Wuenschel🇺🇸 · R. Wada · V.Z. Goldberg🇺🇸 · R. T. deSouza🇺🇸 · S. Hudan🇺🇸 · D. Fang · X-G Cao🇨🇳 · J.B.Natowitz🇺🇸

   Identification of alpha cluster states analogous to the 12C Hoyle state in heavier alpha- conjugate nuclei can provide tests of the existence of alpha condensates in nuclei. Such states are predicted for 16O, 20Ne, 24Mg, 28Si etc. at excitation energies slightly above the multi-alpha particle decay threshold, but have not yet been experimentally identified. The Thick Target Inverse Kinematics (TTIK) technique can be used to study the breakup of excited self-conjugate nuclei into many alpha particles. The reaction 20Ne+{\alpha} was studied using a 20Ne beam at 12 MeV/nucleon from the K150 cyclotron at Texas A&M University. The TTIK method was used to study both single {\alpha}-particle emission and multiple {\alpha}-particle decays. Events with alpha multiplicity up to four were analyzed. The analysis of the three {\alpha} - particle emission data allowed the identification of the Hoyle state and other 12C excited states decaying into three alpha particles. The results are shown and compared with other data available in the literature. Although the statistics for events with alpha multiplicity four is low, the data show a structure at about 15.2 MeV that could indicate the existence in 16O of a state analogous to the 12C Hoyle state. This structure is confirmed by the re-analysis of alpha multiplicity four events from a previous experiment performed at 9.7 MeV/nucleon with a similar setup but lower granularity. Moreover, the reconstructed excitation energy of 24Mg for these events peaks at around 34 MeV, very close to the predicted excitation energy for an excited state analogous to the 12C Hoyle state in 24Mg.

   nucl-exPRC(2018)·30 citations
2. 02*

   A nucleation model analysis of neck emission yields in 124Sn+112,124Sn reactions at 26 MeV/nucleon

   J. Gauthier🇺🇸 · M. Barbui🇺🇸 · X. Cao🇺🇸 · K. Hagel🇺🇸 · R. Wada🇺🇸 · S. Wuenschel🇺🇸 · J. B. Natowitz🇺🇸

   A recent analysis of experimental ternary fission fragment yields using a nucleation moderated statistical equilibrium model reproduced observed yields with fairly good accuracy. In the present work, the same approach is applied to neck emission in peripheral and mid-peripheral 124Sn+112,124Sn collisions at 26A MeV. The model can reasonably reproduce the yields of lithium to silicon isotopes with realistic time and temperature values. A comparison is made between equilibrium constants derived from the present data and those previously obtained for ternary fission of 242Pu.

   nucl-exnucl-th0 citations
3. 03*

   Observation of centrality-dependent acoplanarity for muon pairs produced via two-photon scattering in Pb+Pb collisions at $\sqrt{s_{\mathrm{NN}}}=5.02$ TeV with the ATLAS detector

   ATLAS Collaboration

   This Letter presents a measurement of $\gamma \gamma \to {\mu }^{+}{\mu }^{-}$ production in Pb+Pb collisions recorded by the ATLAS detector at the Large Hadron Collider at $\sqrt{s_{\mathrm{NN}}}=5.02$ TeV with an integrated luminosity of 0.49 nb${}^{-1}$. The azimuthal angle and transverse momentum correlations between the muons are measured as a function of collision centrality. The muon pairs are produced from $\gamma \gamma$ through the interaction of the large electromagnetic fields of the nuclei. The contribution from background sources of muon pairs is removed using a template fit method. In peripheral collisions, the muons exhibit a strong back-to-back correlation consistent with previous measurements of muon pair production in ultra-peripheral collisions. The angular correlations are observed to broaden significantly in central collisions. The modifications are qualitatively consistent with rescattering of the muons while passing through the hot matter produced in the collision.

   nucl-exhep-exPRL(2018)·113 citations
4. 04*

   Doubly-Charged Scalars in the Type-II Seesaw Mechanism: Fundamental Symmetry Tests and High-Energy Searches

   P. S. Bhupal Dev🇺🇸 · Michael J. Ramsey-Musolf🇺🇸 · Yongchao Zhang🇺🇸

   We analyze the sensitivity of low-energy fundamental symmetry tests to interactions mediated by doubly-charged scalars that arise in type-II seesaw models of neutrino mass and their left-right symmetric extensions. We focus on the next generation measurement of the parity-violating asymmetry in Møller scattering planned by the MOLLER collaboration at Jefferson Laboratory. We compare the MOLLER sensitivity to that of searches for charged lepton flavor violation (CLFV) and neutrinoless double beta-decay ($0\nu \beta \beta$-decay) as well as present and possible future high-energy collider probes. We show that for the simplest type-II seesaw scenario, CLFV searches have the greatest sensitivity. However, in a left-right symmetric extension where the scale of parity-breaking is decoupled from the $SU(2{)}_R$-breaking scale, the MOLLER experiment will provide a unique probe of scalar triplet interactions in the right-handed sector for a doubly-charged scalar mass up to $\sim$ 10 TeV and help elucidate the mechanism of $0\nu \beta \beta$-decay.

   ↳ hep-phhep-exnucl-exnucl-thPRD(2018)·65 citations

* Reconstructed cohort: no mailing for this day survives in the archive. Papers are grouped by their submission times and arXiv's announcement cut-off, assuming announcement without delay; positions follow identifier order. Validated at ~91% exact-day agreement against the archived era.