Tue·Oct 8, 2019Tuesday·October 8, 2019

1. 01*

   First direct search for $2ϵ$ and $ϵ{\beta }^{+}$ decay of ${}^{144}$Sm and $2{\beta }^{-}$ decay of ${}^{154}$Sm

   P. Belli🇮🇹 · R. Bernabei🇮🇹 · R.S. Boiko🇺🇦 · F. Cappella🇮🇹 · V. Caracciolo🇮🇹 · R. Cerulli🇮🇹 · F.A. Danevich🇺🇦 · A. Di Marco🇮🇹 · A. Incicchitti🇮🇹 · B.N. Kropivyansky🇺🇦 · M. Laubenstein🇮🇹 · S. Nisi🇮🇹 and 3 other authors

   The first direct search for the double electron capture ($2ϵ$) and the electron capture with positron emission ($ϵ{\beta }^{+}$) in ${}^{144}$Sm to the ground state and to the excited levels of ${}^{144}$Nd was realized by measuring - over 1899 h - a 342 g sample of highly purified samarium oxide (Sm${}_2$O${}_3$) with the ultra-low background HP-Ge $\gamma$ spectrometer GeCris (465 cm${}^3$) at the STELLA facility of the Gran Sasso National Laboratory (LNGS). No effect was observed and half-life limits were estimated at the level of $T_{1/2}\sim (0.1-1.3)\times 10^{20}$ yr (90% C.L.). Moreover, for the first time half-life limits of the double beta ($2{\beta }^{-}$) decay of ${}^{154}$Sm to several excited levels of ${}^{154}$Gd have been set; they are at the level of $T_{1/2}\sim (0.06-8)\times 10^{20}$ yr (90% C.L.).

   nucl-exEPJA(2019)·7 citations
2. 02*

   Hadron production in pp and p-Pb collisions: A mass dependent phenomenon

   S. Sahoo🇮🇳 · R. C. Baral · P. K. Sahu🇮🇳 · M. K. Parida🇮🇳

   The mass dependence plays a significant role in the yield enhancement or suppression of hadrons in pp and p-Pb collisions at the LHC energies. This has been observed by parameterizing the variation of yield ratios between any two hadrons with event charged-particle multiplicity using a single empirical function. We notice that this variation is independent of all quantum numbers and solely depends on masses of hadrons and masses of their valence quarks. The function shows that the amount of quark deconfinement increases with event multiplicity, and the quark coalescence favours more the production of heavier hadrons compared to lighter ones.

   nucl-exnucl-th0 citations
3. 03*

   Pion-induced production of $\Lambda (1520)$ hyperons on nuclei near threshold

   E. Ya. Paryev🇷🇺 · Yu. T. Kiselev🇷🇺

   We study the pion-induced inclusive $\Lambda (1520)$ hyperon production from nuclei near threshold within a nuclear spectral function approach accounting for incoherent primary ${\pi }^{-}$ meson--proton ${\pi }^{-}p\to K^0\Lambda (1520)$ production processes. We calculate the absolute differential and total cross sections for the production of $\Lambda (1520)$ hyperons off carbon and tungsten nuclei at laboratory angles of 0${}^{\circ }$--10${}^{\circ }$, 10${}^{\circ }$--45${}^{\circ }$ and 45${}^{\circ }$--85${}^{\circ }$ by ${\pi }^{-}$ mesons with momentum of 1.7 GeV/c as well as their relative (transparency ratio) differential and integral yields from these nuclei within four scenarios for their total in-medium width. We demonstrate that these absolute observables, contrary to the relative ones, reveal some sensitivity to the $\Lambda (1520)$ in-medium width. Therefore, their measurement in a dedicated experiment at the GSI pion beam facility will allow to shed light on this width.

   ↳ nucl-thnucl-exNPA(2019)·3 citations
4. 04*

   Possible lightest $\Xi$ Hypernucleus with Modern $\Xi N$ Interactions

   E. Hiyama🇯🇵 · K. Sasaki🇯🇵 · T. Miyamoto🇯🇵 · T. Doi🇯🇵 · T. Hatsuda🇯🇵 · Y. Yamamoto🇯🇵 · Th. A. Rijken🇳🇱

   Experimental evidence exists that the $\Xi$-nucleus interaction is attractive. We search for $NN\Xi$ and $NNN\Xi$ bound systems on the basis of the AV8 $NN$ potential combined with either a phenomenological Nijmegen $\Xi N$ potential or a first principles HAL QCD $\Xi N$ potential. The binding energies of the three-body and four-body systems (below the $d+\Xi$ and ${}^3\mathrm{H}$/${}^3\mathrm{He}+\Xi$ thresholds, respectively) are calculated by a high precision variational approach, the Gaussian Expansion Method. Although the two $\Xi N$ potentials have significantly different isospin ($T$) and spin ($S$) dependence, the $NNN\Xi$ system with quantum numbers $(T=0,J^{\pi }=1^{+}$) appears to be bound (one deep for Nijmegen and one shallow for HAL QCD) below the ${}^3\mathrm{H}$/${}^3\mathrm{He}+\Xi$ threshold. Experimental implications for such a state are discussed.

   ↳ nucl-thhep-lathep-phnucl-exPRL(2020)·61 citations
5. 05*

   Complications in the interpretation of the charge asymmetry dependent $\pi$ flow for the chiral magnetic wave

   Hao-jie Xu🇨🇳 · Jie Zhao🇺🇸 · Yicheng Feng🇺🇸 · Fuqiang Wang🇺🇸

   The charge asymmetry ($A_{\mathrm{ch}}$) dependence of the ${\pi }^{-}$ and ${\pi }^{+}$ elliptic flow difference, $\Delta v_2(A_{\mathrm{ch}})$, has been regarded as a sensitive observable for the possible chiral magnetic wave (CMW) in relativistic heavy ion collisions. In this work, we first demonstrate that, due to non-flow backgrounds, the flow measurements by the Q-cumulant method using all charged particles as reference introduce a trivial linear term to $\Delta v_2(A_{\mathrm{ch}})$. The trivial slope can be negative in the triangle flow difference $\Delta v_3(A_{\mathrm{ch}})$ if the non-flow is dominated by back-to-back pairs. After eliminating the trivial term, we find that the non-flow between like-sign pairs gives rise to an additional positive slope to $\Delta v_2(A_{\mathrm{ch}})$ because of the larger dilution effect to ${\pi }^{+}$ (${\pi }^{-}$) at positive (negative) $A_{\mathrm{ch}}$. We further find that the competition between different $\pi$ sources can introduce another non-trivial linear-$A_{\mathrm{ch}}$ term due to their different multiplicity fluctuations and anisotropic flows. We then study the effect of neutral cluster (resonance) decays as a mechanism for local charge conservation on the slope parameter of $\Delta v_2(A_{\mathrm{ch}})$. We find that the slope parameter is sensitive to the kinematics of those neutral clusters. Light resonances give positive slopes while heavy resonances give negative slopes. Local charge conservation from continuum cluster mass distribution can give a positive slope parameter comparable to experimental data. Our studies indicate that many non-CMW physics mechanisms can give rise to a $A_{\mathrm{ch}}$-dependent $\Delta v_2(A_{\mathrm{ch}})$ and the interpretation of $\Delta v_2(A_{\mathrm{ch}})$ in terms of the CMW is delicate.

   ↳ nucl-thnucl-exPRC(2020)·14 citations
6. 06*

   Investigating saturation effects in ultraperipheral collisions at the LHC with the color dipole model

   Bharath Sambasivam🇺🇸 · Tobias Toll🇮🇳 · Thomas Ullrich🇺🇸

   We investigate saturation effects in $ep$ scattering as well as in ultraperipheral $p$A and AA collisions at small $x$ with four variants of the impact parameter dependent color dipole model: with and without gluon saturation and with and without a novel mechanism that suppresses unphysical dipole radii above the confinement scale, a problem not addressed by most implementations. We show that $ep$ scattering at HERA can be very well described by any of the four variants. When going from $ep$ to $e$A scattering, saturation effects are expected to increase as $\sim$A${}^{1/3}$. In lieu of an electron-ion collider, we confront the different versions of the dipole model with data recorded in ultraperipheral collisions at the LHC in order to estimate the sensitivity of the data to gluon saturation in the target nuclei. We find that ultraperipheral PbPb collisions indicate strong saturation effects while $p$Pb collisions turn out to not have any discriminating power to distinguish saturation from non-saturation scenarios.

   ↳ hep-phnucl-exnucl-thPLB(2020)·41 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.