Fri·Jul 26, 2019Friday·July 26, 2019

1. 01*

   Transverse Spin Asymmetries in the $p^{\uparrow }p\to p{\pi }^{0}X$ Process at STAR

   Christopher Dilks🇺🇸

   A significant sample of $p^{\uparrow }p\to p{\pi }^{0}X$ events has been observed at STAR in $\sqrt{s}=200$ GeV transversely polarized $pp$ collisions, where an isolated ${\pi }^0$ is detected in the forward pseudorapidity range $2.65<\eta <3.9$ along with the forward-going proton $p$, which scatters with a near-beam forward pseudorapidity into Roman Pot detectors. The sum of the ${\pi }^0$ and the scattered proton energies is consistent with the incident proton energy of 100 GeV, indicating that no further particles are produced in this direction. It is postulated that the forward incident proton may have fluctuated into a $p+{\pi }^0$ system, with an angular momentum correlated with the initial proton spin. The backward-going proton interacts with the $p+{\pi }^0$ system, which then separates such that the ${\pi }^0$ has a transverse momentum of $\sim 2$ GeV/$c$ and the proton has a transverse momentum of $\sim 0.2$ GeV/$c$, while the backward proton shatters into the remaining particles $X$. Correlations between the ${\pi }^0$ and scattered proton will be presented, along with single-spin asymmetries which depend on the azimuthal angles of both the pion and the proton. This is the first time that spin asymmetries have been explored for this process, and a model to explain their azimuthal dependence is needed.

   ↳ hep-exnucl-exPoS(2019)·1 citation
2. 02*

   Bayesian Inference of High-density Nuclear Symmetry Energy from Radii of Canonical Neutron Stars

   Wen-Jie Xie🇺🇸 · Bao-An Li🇺🇸

   The radius $R_{1.4}$ of neutron stars (NSs) with a mass of 1.4 M${}_{\odot }$ has been extracted consistently in many recent studies in the literature. Using representative $R_{1.4}$ data, we infer high-density nuclear symmetry energy $E_{\mathrm{sym}}(\rho )$ and the associated nucleon specific energy $E_0(\rho )$ in symmetric nuclear matter (SNM) within a Bayesian statistical approach using an explicitly isospin-dependent parametric Equation of State (EOS) for nucleonic matter. We found that: (1) The available astrophysical data can already improve significantly our current knowledge about the EOS in the density range of ${\rho }_0-2.5{\rho }_0$. In particular, the symmetry energy at twice the saturation density ${\rho }_0$ of nuclear matter is determined to be $E_{\mathrm{sym}}(2{\rho }_0)$ =39.2${}_{-8.2}^{+12.1}$ MeV at 68\% confidence level. (2) A precise measurement of the $R_{1.4}$ alone with a 4\% 1$\sigma$ statistical error but no systematic error will not improve much the constraints on the EOS of dense neutron-rich nucleonic matter compared to what we extracted from using the available radius data. (3) The $R_{1.4}$ radius data and other general conditions, such as the observed NS maximum mass and causality condition introduce strong correlations for the high-order EOS parameters. Consequently, the high-density behavior of $E_{\mathrm{sym}}(\rho )$ inferred depends strongly on how the high-density SNM EOS $E_0(\rho )$ is parameterized, and vice versa. (4) The value of the observed maximum NS mass and whether it is used as a sharp cut-off for the minimum maximum mass or through a Gaussian distribution affect significantly the lower boundaries of both the $E_0(\rho )$ and $E_{\mathrm{sym}}(\rho )$ only at densities higher than about $2.5{\rho }_0$.

   ↳ astro-ph.HEastro-ph.SRnucl-exnucl-thApJ(2019)·125 citations
3. 03*

   Underlying structure of collective bands and self-organization in quantum systems

   Takaharu Otsuka🇯🇵 · Yusuke Tsunoda🇯🇵 · Takashi Abe · Noritaka Shimizu🇯🇵 · Piet Van Duppen🇧🇪

   The underlying structure of low-lying collective bands of atomic nuclei is discussed from a novel perspective on the interplay between single-particle and collective degrees of freedom, by utilizing state-of-the-art configuration interaction calculations on heavy nuclei. Besides the multipole components of the nucleon-nucleon interaction that drive collective modes forming those bands, the monopole component is shown to control the resistance against such modes. The calculated structure of 154Sm corresponds to coexistence between prolate and triaxial shapes, while that of 166Er exhibits a deformed shape with a strong triaxial instability. Both findings differ from traditional views based on beta/gamma vibrations. The formation of collective bands is shown to be facilitated from a self-organization mechanism.

   ↳ nucl-thnucl-exPRL(2019)·66 citations
4. 04*

   A Novel Energy Resolved X-Ray Semiconductor Detector

   Tengfei Yan · Chunlei Yang🇺🇸 · Xiaodong Cui

   The hyperspectral X-ray imaging has been long sought in various fields from material analysis to medical diagnosis. Here we propose a new semiconductor detector structure to realize energy-resolved imaging at potentially low cost. The working principle is based on the strong energy-dependent absorption of X-ray in solids. Namely, depending on the energy, X-ray photons experience dramatically different attenuation. An array or matrix of semiconductor cells is to map the X-ray intensity along its trajectory. The X-ray spectrum could be extracted from a Laplace like transform or even a supervised machine learning. We demonstrated an energy-resolved X-ray detection with a regular silicon camera.

   ↳ physics.ins-detnucl-exphysics.app-phphysics.med-ph0 citations
5. 05*

   Pseudorapidity dependent hydrodynamic response in heavy-ion collisions

   Hui Li🇨🇳 · Li Yan🇨🇳

   We propose a differential hydrodynamic response relation, $V_2(\zeta )=\int d\xi G(\zeta -\xi ){\mathcal{E}}_2(\xi )$, to describe the formation of a pseudorapidity dependent elliptic flow in heavy-ion collisions, in response to a fluctuating three-dimensional initial density profile. By analyzing the medium expansion using event-by-event simulations of 3+1D MUSIC, with initial conditions generated via the AMPT model, the differential response relation is verified. Given the response relation, we are able to separate the two-point correlation of elliptic flow in pseudorapidity into fluid response and two-point correlation of initial eccentricity. The fluid response contains information of the speed of sound and shear viscosity of the medium. From the pseudorapidity dependent response relation, a finite radius of convergence of hydrodynamic gradient expansion is obtained with respect to realistic fluids in heavy-ion collisions.

   ↳ nucl-thhep-phnucl-exPLB(2020)·11 citations
6. 06*

   Characterization of Light Production and Transport in Tellurium Dioxide Crystals

   R. G. Huang🇺🇸 · G. Benato🇺🇸 · J. Caravaca🇺🇸 · Yu. G. Kolomensky🇺🇸 · B. J. Land🇺🇸 · G. D. Orebi Gann🇺🇸 · B. Schmidt🇺🇸

   Simultaneous measurement of phonon and light signatures is an effective way to reduce the backgrounds and increase the sensitivity of CUPID, a next-generation bolometric neutrinoless double-beta decay ($0\nu \beta \beta$) experiment. Light emission in tellurium dioxide (TeO${}_2$) crystals, one of the candidate materials for CUPID, is dominated by faint Cherenkov radiation, and the high refractive index of TeO${}_2$ complicates light collection. Positive identification of $0\nu \beta \beta$ events therefore requires high-sensitivity light detectors and careful optimization of light transport. A detailed microphysical understanding of the optical properties of TeO${}_2$ crystals is essential for such optimization. We present a set of quantitative measurements of light production and transport in a cubic TeO${}_2$ crystal, verified with a complete optical model and calibrated against a UVT acrylic standard. We measure the optical surface properties of the crystal, and set stringent limits on the amount of room-temperature scintillation in TeO${}_2$ for $\beta$ and $\alpha$ particles of 5.3 and 8 photons / MeV, respectively, at 90% confidence. The techniques described here can be used to optimize and verify the particle identification capabilities of CUPID.

   ↳ physics.ins-detnucl-exJINST(2019)·2 citations
7. 07*

   Primordial fluctuations in heavy-ion collisions

   François Gelis🇫🇷 · Giuliano Giacalone🇫🇷 · Pablo Guerrero-Rodríguez🇪🇸 · Cyrille Marquet🇫🇷 · Jean-Yves Ollitrault🇫🇷

   We present a simple description of the energy density profile created in a nucleus-nucleus collision, motivated by high-energy QCD. The energy density is modeled as the sum of contributions coming from elementary collisions between localized charges and a smooth nucleus. Each of these interactions creates a sharply-peaked source of energy density falling off at large distances like $1/r^2$, corresponding to the two-dimensional Coulomb field of a point charge. Our model reproduces the one-point and two-point functions of the energy density field calculated in the framework of the color glass condensate effective theory, to leading logarithmic accuracy. We apply it to the description of eccentricity fluctuations. Unlike other existing models of initial conditions for heavy-ion collisions, it allows us to reproduce simultaneously the centrality dependence of elliptic and triangular flow.

   ↳ nucl-thhep-phnucl-ex21 citations
8. 08*

   Temperature and fluid velocity on the freeze-out surface from $\pi$, $K$, $p$ spectra in pp, p--Pb and Pb--Pb collisions

   Aleksas Mazeliauskas🇨🇭 · Vytautas Vislavicius🇩🇰

   We present a new approach to take into account resonance decays in the blast-wave model fits of identified hadron spectra. Thanks to pre-calculated decayed particle spectra, we are able to extract, in a matter of seconds, the multiplicity dependence of the single freeze-out temperature $T_{\mathrm{fo}}$, average fluid velocity $⟨{\beta }_{\mathrm{T}}⟩$, velocity exponent $n$, and the volume $dV/dy$ of an expanding fireball. In contrast to blast-wave fits without resonance feed-down, our approach results in a freeze-out temperature of $T_{\mathrm{fo}}\approx 150\text{MeV}$, which has only weak dependence on multiplicity and collision system. Finally, we discuss separate chemical and kinetic freeze-outs separated by partial chemical equilibrium.

   ↳ hep-phnucl-exnucl-thPRC(2020)·49 citations
9. 09*

   Pion-proton correlation in neutrino interactions on nuclei

   Tejin Cai🇺🇸 · Xianguo Lu🇬🇧 · Daniel Ruterbories🇺🇸

   In neutrino-nucleus interactions, a proton produced with a correlated pion might exhibit a left-right asymmetry relative to the lepton scattering plane even when the pion is absorbed. Absent in other proton production mechanisms, such an asymmetry measured in charged-current pionless production could reveal the details of the absorbed-pion events that are otherwise inaccessible. In this study, we demonstrate the idea of using final-state proton left-right asymmetries to quantify the absorbed-pion event fraction and underlying kinematics. This technique might provide critical information that helps constrain all underlying channels in neutrino-nucleus interactions in the GeV regime.

   ↳ hep-exhep-phnucl-exPRD(2019)·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.