Mon·Feb 10, 2020Monday·February 10, 2020

1. 01*

   Search for exotic spin-dependent interactions using polarized helium

   P.-H. Chu🇺🇸 · Y. J. Kim🇰🇷 · I. M. Savukov🇺🇸

   We investigate the sensitivities of searches for exotic spin-dependent interactions between the polarized nuclear spins of ${}^3$He and the particles of unpolarized or polarized solid-state masses using the frequency method and the resonance method. In the frequency method, the spin-dependent interactions act as an effective static magnetic field, causing the frequency shift to the spin precession of ${}^3$He. In the resonance method, proposed by Arvanitaki and Geraci [Phys. Rev. Lett. 113, 161801 (2014)] for the significant improvement of the experimental sensitivities on the spin-dependent interactions, the mass movement is modulated at the Larmor frequency of ${}^3$He. This results in the modulating spin-dependent interactions inducing an effective oscillatory magnetic field, which can tilt the ${}^3$He spins, similarly as an oscillatory magnetic field in nuclear magnetic resonance. We estimate the sensitivities of the searches using a room-temperature ${}^3$He target for its extremely long relaxation time. New limits on the coupling strengths of the spin-dependent interactions can be set in the interaction length range below $10^{-1}$ m.

   nucl-ex4 citations
2. 02*

   Examining the EMC Effect using the $F_2^n$ neutron structure function

   H. Szumila-Vance🇺🇸 · C. Keppel🇺🇸 · S. Escalante · N. Kalantarians🇺🇸

   The persistently mysterious deviations from unity of the ratio of nuclear target structure functions to those of deuterium as measured in deep inelastic scattering (often termed the "EMC Effect") have become the canonical observable for studies of nuclear medium modifications to free nucleon structure in the valence regime. The structure function of the free proton is well known from numerous experiments spanning decades. The free neutron structure function, however, has remained difficult to access. Recently it has been extracted in a systematic study of the global data within a parton distribution function extraction framework and is available from the CTEQ-Jefferson Lab (CJ) Collaboration. Here, we leverage the latter to introduce a new method to study the EMC Effect in nuclei by re-examining existing data in light of the the magnitude of the medium modifications to the free neutron and proton structure functions independently. From the extraction of the free neutron from world data, it is possible to examine the nuclear effects in deuterium and their contribution to our interpretation of the EMC Effect. In this study, we observe that the ratio of the deuteron to the sum of the free neutron and proton structure functions has some $x_B$ and $Q^2$ dependencies that impact the magnitude of the EMC Effect as typically observed. Specifically, different EMC slopes are obtained when data from different $x_B$ and $Q^2$ values are utilized. While a linear correlation persists between the EMC and short range correlation effects, the slope is modified when deuteron nuclear effects are removed.

   nucl-exPRC(2021)·3 citations
3. 03*

   QCD equation of state at finite densities for nuclear collisions

   Akihiko Monnai🇯🇵 · Björn Schenke🇺🇸 · Chun Shen🇺🇸

   We construct the QCD equation of state at finite chemical potentials including net baryon, electric charge, and strangeness based on the results of lattice QCD simulations and the hadron resonance gas model. The situation of strangeness neutrality and a fixed charge-to-baryon ratio, which resembles that of heavy nuclei, is considered for the application to relativistic heavy-ion collisions. This increases the values of baryon chemical potential compared to the case of vanishing strangeness and electric charge chemical potentials, modifying the fireball trajectory in the phase diagram. We perform viscous hydrodynamic simulations and demonstrate the importance of multiple chemical potentials for identified particle production in heavy-ion collisions at the RHIC and SPS beam energy scan energies.

   ↳ nucl-thhep-phnucl-exNPA(2021)·4 citations
4. 04*

   On the excitation of the $2_1^{+}$ state in ${}^{12}$C in the $(e,e^{\prime }\gamma )$ reaction

   D. H. Jakubassa-Amundsen🇩🇪 · V. Yu. Ponomarev🇩🇪

   The excitation of the carbon $2^{+}$ state at 4.439 MeV by $70-150$ MeV electron impact and its subsequent decay to the ground state by photon emission is described within the distorted-wave Born approximation. The transition densities are obtained from the nuclear quasiparticle phonon model. The photon angular distributions are compared with earlier results and with experiment, including the influence of bremsstrahlung. Predictions for spin asymmetries in the case of polarized electron impact are also made.

   ↳ nucl-thnucl-exEPJA(2020)·2 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.