Tue·Feb 24, 2015Tuesday·February 24, 2015

1. 01*

   Mixed-symmetry octupole and hexadecapole excitations in the N=52 isotones

   A. Hennig🇩🇪 · M. Spieker🇩🇪 · V. Werner🇺🇸 · T. Ahn🇺🇸 · V. Anagnostatou · N. Cooper🇺🇸 · V. Derya🇩🇪 · M. Elvers · J. Endres🇩🇪 · P. Goddard🇺🇸 · A. Heinz🇸🇪 · R. O. Huges and 9 other authors

   Background: Excitations with mixed proton-neutron symmetry have been previously observed in the $N=52$ isotones. Besides the well established quadrupole mixed-symmetry states (MSS), octupole and hexadecapole MSS have been recently proposed for the nuclei ${}^{92}$Zr and ${}^{94}$Mo. Purpose: The heaviest stable $N=52$ isotone ${}^{96}$Ru was investigated to study the evolution of octupole and hexadecapole MSS with increasing proton number. Methods: Two inelastic proton-scattering experiments on ${}^{96}$Ru were performed to extract branching ratios, multipole mixing ratios, and level lifetimes. From the combined data, absolute transition strengths were calculated. Results: Strong $M1$ transitions between the lowest-lying $3^{-}$ and $4^{+}$ states were observed, providing evidence for a one-phonon mixed-symmetry character of the $3_2^{(-)}$ and $4_2^{+}$ states. Conclusions: $sdg$-IBM-2 calculations were performed for ${}^{96}$Ru. The results are in excellent agreement with the experimental data, pointing out a one-phonon hexadecapole mixed-symmetry character of the $4_2^{+}$ state. The $⟨3_1^{-}||M1||3_2^{(-)}⟩$ matrix element is found to scale with the $<2_{\mathrm{s}}^{+}||M1||2_{\mathrm{ms}}^{+}>$ matrix element.

   nucl-exnucl-thPRC(2014)·11 citations
2. 02*

   Benchmarking Nuclear Fission Theory

   G.F. Bertsch🇺🇸 · W. Loveland🇺🇸 · W. Nazarewicz🇺🇸 · P. Talou🇺🇸

   We suggest a small set of fission observables to be used as test cases for validation of theoretical calculations. The purpose is to provide common data to facilitate the comparison of different fission theories and models. The proposed observables are chosen from fission barriers, spontaneous fission lifetimes, fission yield characteristics, and fission isomer excitation energies.

   ↳ nucl-thnucl-exJ.Phys.G(2015)·30 citations
3. 03*

   Neutron Interferometry constrains dark energy chameleon fields

   H. Lemmel🇦🇹 · Ph. Brax🇫🇷 · A. N. Ivanov🇦🇹 · T. Jenke🇦🇹 · G. Pignol🇫🇷 · M. Pitschmann🇦🇹 · T. Potocar🇦🇹 · M. Wellenzohn🇦🇹 · M. Zawisky🇦🇹 · H. Abele🇦🇹

   We present phase shift measurements for neutron matter waves in vacuum and in low pressure Helium using a method originally developed for neutron scattering length measurements in neutron interferometry. We search for phase shifts associated with a coupling to scalar fields. We set stringent limits for a scalar chameleon field, a prominent quintessence dark energy candidate. We find that the coupling constant $\beta$ is less than 1.9 $\times 10^7$~for $n=1$ at 95\% confidence level, where $n$ is an input parameter of the self--interaction of the chameleon field $\phi$ inversely proportional to ${\phi }^n$.

   ↳ hep-phhep-exnucl-exquant-phPLB(2015)·101 citations
4. 04*

   Hadrons from Coalescence plus Fragmentation in AA collisions from RHIC to LHC energy

   Vincenzo Minissale🇮🇹 · Francesco Scardina🇮🇹 · Vincenzo Greco🇮🇹

   In a coalescence plus independent fragmentation approach we calculate the $p_T$ spectra of the main hadrons: $\pi ,K,p,\bar{p},\Lambda ,\varphi$ in a wide range of transverse momentum from low $p_T$ up to about 10 GeV. The approach in its main features was developed several years ago at RHIC energy. Augmenting the model with the inclusion of some more main resonance decays, we show that the approach correctly predicts the evolution of the $p_T$ spectra from RHIC to LHC energy and in particular the baryon-to-meson ratios $p/\pi ,\bar{p}/\pi ,\Lambda /K$ that reach a value of the order of unit at $p_T\sim 3\mathrm{GeV}$. This is achieved without any change of the coalescence parameters. The more recent availability of experimental data up to $p_T\sim 10\mathrm{GeV}$ for $\Lambda$ spectrum as well as for $p/\pi$ and $\Lambda /K$ shows some lack of yield in a limited $p_T$ range around 6 GeV. This indicates that the baryons $p_T$ spectra from AKK fragmentation functions are too flat at $p_T\lesssim 8\mathrm{GeV}$. We also show that in a coalescence plus fragmentation approach one predicts a nearly $p_T$ independent $p/\varphi$ ratio up to $p_T\sim 4\mathrm{GeV}$ followed by a significant decrease at higher $p_T$. Such a behavior is driven by a similar radial flow effect at $p_T<2\mathrm{GeV}$ and the dominance of fragmentation for $\varphi$ at larger $p_T$.

   ↳ nucl-thhep-phnucl-exPRC(2015)·80 citations
5. 05*

   Testing Lorentz invariance in orbital electron capture

   K.K. Vos🇳🇱 · H.W. Wilschut🇳🇱 · R.G.E. Timmermans🇳🇱

   Searches for Lorentz violation were recently extended to the weak sector, in particular neutron and nuclear $\beta$ decay [1]. From experiments on forbidden $\beta$-decay transitions strong limits in the range of $10^{-6}$-$10^{-8}$ were obtained on Lorentz-violating components of the $W$-boson propagator [2]. In order to improve on these limits strong sources have to be considered. In this Brief Report we study isotopes that undergo orbital electron capture and allow experiments at high decay rates and low dose. We derive the expressions for the Lorentz-violating differential decay rate and discuss the options for competitive experiments and their required precision.

   ↳ hep-phnucl-exnucl-thPRC(2015)·19 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.