Tue·Nov 21, 2017Tuesday·November 21, 2017

1. 01*

   Mechanisms of Coulomb dissociation processes

   Zoltàn Seres🇭🇺

   The Coulomb dissociation is studied of the ${}^{8}L$i nuclei on Pb target at energies 40.3 and 69.5 MeV/nucleon, in the experiment NSCL #03038. The ${}^{6,7}$Li, ${}^{4,6}$He, and ${}^2$H fragments were identified. The resonance decay and the direct breakup reactions were observed. The data give experimental evidence that the Coulomb dissociation is a two-step process. The projectile in the approaching phase is braked down and the valence neutron gets forced oscillation. The increasing Coulonb force holds the projectile and brings through the excited states up to the closest approach point. There released, the projectile is trapped into a primary, highly excited state in the continuum. The lifetime of the primary state depends on the multipolarity of the deformed projectile. At intermediate energy the collision is a sudden reaction, the valence neutron may stay --- during the impact --- in the forward or backward hemisphere of the nucleus, and the orbit of the valence neutron gets prolate or oblate, dipole or multipole deformation and the nucleus gets single-particle or collective excitation. The primary excited states, developing will decay prompt or delayed into the same reaction channel, resulting in the two decay mechanisms.

   nucl-ex0 citations
2. 02*

   Lévy analysis of HBT correlation functions in $\sqrt{s_{\mathrm{NN}}}=$ 62 GeV and 39 GeV Au+Au collisions at PHENIX

   Dániel Kincses (for the PHENIX Collaboration)🇭🇺

   The phase diagram of strongly interacting matter can be explored by analyzing data of heavy-ion collisions at different center of mass collision energies. For investigating the space-time structure of the hadron emission source, HBT correlation measurements are among the best tools. In this paper we present the latest results from the RHIC PHENIX experiment on such measurements in $\sqrt{s_{\mathrm{NN}}}=$ 39 GeV and 62 GeV Au+Au collisions.

   nucl-exUniverse(2018)·14 citations
3. 03*

   Scaling within the Spectral Function approach

   J. E. Sobczyk🇪🇸 · N. Rocco🇬🇧 · A. Lovato🇺🇸 · J. Nieves🇪🇸

   Scaling features of the nuclear electromagnetic response functions unveil aspects of nuclear dynamics that are crucial for interpretating neutrino- and electron-scattering data. In the large momentum-transfer regime, the nucleon-density response function defines a universal scaling function, which is independent of the nature of the probe. In this work, we analyze the nucleon-density response function of ${}^{12}$C, neglecting collective excitations. We employ particle and hole spectral functions obtained within two distinct many-body methods, both widely used to describe electroweak reactions in nuclei. We show that the two approaches provide compatible nucleon-density scaling functions that for large momentum transfers satisfy first-kind scaling. Both methods yield scaling functions characterized by an asymmetric shape, although less pronounced than that of experimental scaling functions. This asymmetry, only mildly affected by final state interactions, is mostly due to nucleon-nucleon correlations, encoded in the continuum component of the hole SF.

   ↳ nucl-thhep-exnucl-exPRC(2018)·12 citations
4. 04*

   Energy dependence of non-local potentials

   A.E. Lovell🇺🇸 · P.-L. Bacq · P. Capel🇩🇪 · F.M. Nunes🇺🇸 · L.J. Titus🇺🇸

   Recently a variety of studies have shown the importance of including non-locality in the description of reactions. The goal of this work is to revisit the phenomenological approach to determining non-local optical potentials from elastic scattering. We perform a ${\chi }^2$ analysis of neutron elastic scattering data off ${}^{40}$Ca, ${}^{90}$Zr and ${}^{208}$Pb at energies $E\approx 5-40$ MeV, assuming a Perey and Buck or Tian, Pang, and Ma non-local form for the optical potential. We introduce energy and asymmetry dependencies in the imaginary part of the potential and refit the data to obtain a global parameterization. Independently of the starting point in the minimization procedure, an energy dependence in the imaginary depth is required for a good description of the data across the included energy range. We present two parameterizations, both of which represent an improvement over the original potentials for the fitted nuclei as well as for other nuclei not included in our fit. Our results show that, even when including the standard Gaussian non-locality in optical potentials, a significant energy dependence is required to describe elastic-scattering data.

   ↳ nucl-thnucl-exPRC(2017)·22 citations
5. 05*

   Container evolution for cluster structures in ${}^{16}\mathrm{O}$

   Y. Funaki🇯🇵

   Background: $\alpha +{}^{12}\mathrm{C}$ clustering in ${}^{16}\mathrm{O}$ has been of historical importance in nuclear clustering. In the last 15 years the $4\alpha$ condensate state has been proposed as a new-type cluster state. Purpose: The aim is to reveal a dynamical process of the formation of different kinds of cluster states, in terms of a "container" aspect of clusters, in ${}^{16}\mathrm{O}$. Method: The so-called THSR wave function for the $4\alpha$ clusters is extended to inclusion of two different containers occupied independently by the ${}^{12}\mathrm{C}$ $(3\alpha )$ and $\alpha$ clusters. Results: The five $J^{\pi }=0^{+}$ states with $4\alpha$ tetrahedral shape, $\alpha +{}^{12}\mathrm{C}$ cluster structures, and the $4\alpha$ condensate character, are found to be represented, to good approximation, by single configurations of the extended THSR wave function with containers of appropriate shape and size. Conclusions: It is demonstrated in ${}^{16}\mathrm{O}$ that the dynamical evolution of cluster structures can be caused by size and shape evolution of a container occupied with clusters. The $\alpha$ condensate with gaslike $4\alpha$ configuration appears as a limit of the cluster formation.

   ↳ nucl-thnucl-exPRC(2018)·31 citations
6. 06*

   Measurement of ${}^{144}\mathrm{Pr}$ beta-spectrum with Si(Li) detectors for the purpose of determining the spectrum of electron antineutrinos

   A.V. Derbin🇷🇺 · S.V. Bakhlanov🇷🇺 · I.S. Drachnev🇷🇺 · I.P. Filipov🇷🇺 · L.A. Lukyanchenko🇷🇺 · I.N. Machulin🇷🇺 · V.N. Muratova🇷🇺 · N.V. Pilipenko🇷🇺 · D.A. Semenov🇷🇺 · E.V. Unzhakov🇷🇺

   Here we present the specifications of the newly developed beta-spectrometer based on thick full absorption Si(Li) detector. The spectrometer can be used for precision measurements of various beta-spectra, namely for the beta-spectrum shape study of ${}^{144}$Pr, which is considered to be the most promising anti-neutrino source for sterile neutrino searches.

   ↳ physics.ins-dethep-exhep-phnucl-ex0 citations
7. 07*

   New quasibound states of the compound nucleus in $\alpha$-particle capture by the nucleus

   Sergei P. Maydanyuk (1 and2) · Peng-Ming Zhang (1) · Li-Ping Zou (1) ((1) Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou, 730000, China, (2) Institute for Nuclear Research, National Academy of Sciences of Ukraine, Kiev, 03680, Ukraine)

   We generalize the theory of nuclear decay and capture of Gamow that is based on tunneling through the barrier and internal oscillations inside the nucleus. In our formalism an additional factor is obtained, which describes distribution of the wave function of the $\alpha$ particle inside the nuclear region. We discover new most stable states (called quasibound states) of the compound nucleus (CN) formed during the capture of $\alpha$ particle by the nucleus. With a simple example, we explain why these states cannot appear in traditional calculations of the $\alpha$ capture cross sections based on monotonic penetrabilities of a barrier, but they appear in a complete description of the evolution of the CN. Our result is obtained by a complete description of the CN evolution, which has the advantages of (1) a clear picture of the formation of the CN and its disintegration, (2) a detailed quantum description of the CN, (3) tests of the calculated amplitudes based on quantum mechanics (not realized in other approaches), and (4) high accuracy of calculations (not achieved in other approaches). These peculiarities are shown with the capture reaction of $\alpha {+}^{44}\mathrm{Ca}$. We predict quasibound energy levels and determine fusion probabilities for this reaction. The difference between our approach and theory of quasistationary states with complex energies applied for the $\alpha$ capture is also discussed. We show (1) that theory does not provide calculations for the cross section of $\alpha$ capture (according to modern models of the $\alpha$ capture), in contrast with our formalism, and (2) these two approaches describe different states of the $\alpha$ capture (for the same $\alpha$-nucleus potential).

   ↳ nucl-thhep-phnucl-exPRC(2017)·13 citations
8. 08*

   $\mathrm{J}/\psi$ production as a function of multiplicity in pp and p-Pb collisions with ALICE

   Jana Crkovská (for the ALICE collaboration)🇫🇷

   The multiplicity dependence of charmed-particle production can unveil new information on processes taking part at the parton level and on the interplay of soft and hard production mechanisms in collisions of relativistic hadrons. In this contribution, we report on multiplicity-differential measurements of $\mathrm{J}/\psi$ in pp and p-Pb collisions studied by the ALICE Collaboration. Comparisons between measurements at different energies are drawn as well as comparisons with $\mathrm{D}$ mesons. We also discuss the comparison with different theoretical predictions.

   ↳ hep-exnucl-exPoS(2017)·0 citations
9. 09*

   Critical point of nuclear matter and beam energy dependence of net proton number fluctuations

   Volodymyr Vovchenko🇩🇪 · Lijia Jiang🇩🇪 · Mark I. Gorenstein🇺🇦 · Horst Stoecker🇩🇪

   The beam energy dependence of net baryon number susceptibilities is studied in the framework of the hadron resonance gas model with the attractive and repulsive van der Waals interactions between baryons. The collision energy dependences for the skewness $S\sigma$ and kurtosis $\kappa {\sigma }^2$ deviate significantly from the Poisson baseline and demonstrate the existence of rich structures at moderate collision energies. This behavior may result from the critical end point of the nuclear liquid-gas first order phase transition. In particular, $\kappa {\sigma }^2$ shows a non-monotonic energy dependence, and, in contrast to the standard scenario for the QCD critical point, it does not decrease at low collision energies. It is also found that the measurable net proton fluctuations differ significantly from the net baryon fluctuations when interactions between baryons cannot be neglected. The results are compared with the experimental net proton number fluctuations measured by the STAR collaboration.

   ↳ nucl-thhep-phnucl-exPRC(2018)·37 citations
10. 10*

    The impact of $S$-wave thresholds $D_{s1}{\bar{D}}_s+c.c.$ and $D_{s0}{\bar{D}}_s^{\ast }+c.c.$ on vector charmonium spectrum

    Zheng Cao🇨🇳 · Qiang Zhao🇨🇳

    By investigating the very closely lied $D_{s1}{\bar{D}}_s+c.c.$ and $D_{s0}{\bar{D}}_s^{\ast }+c.c.$ thresholds at about 4.43 GeV we propose that the $\psi (4415)$ and $\psi (4160)$ can be mixing states between the dynamic generated states of the strong $S$-wave $D_{s1}{\bar{D}}_s+c.c.$ and $D_{s0}{\bar{D}}_s^{\ast }+c.c.$ interactions and the quark model states $\psi (4S)$ and $\psi (2D)$. We investigate the $J/\psi K\bar{K}$ final states and invariant mass spectrum of $J/\psi K$ to demonstrate that nontrivial lineshapes can arise from such a mechanism. This process, which goes through triangle loop transitions, is located in the vicinity of the so-called "triangle singularity (TS)" kinematics. As a result, it provides a special mechanism for the production of exotic states $Z_{cs}$, which is the strange partner of $Z_c(3900)$, but with flavor contents of $c\bar{c}q\bar{s}$ (or $c\bar{c}s\bar{q}$) with $q$ denoting $u/d$ quarks. The lineshapes of the $e^{+}{e}^{-}\to J/\psi K\bar{K}$ cross sections and $J/\psi K(J/\psi \bar{K})$ spectrum are sensitive to the dynamically generated state, and we demonstrate that a pole structure can be easily distinguished from open threshold CUSP effects if an exotic state is created. A precise measurement of the cross section lineshapes can test such a mixing mechanism and provide navel information for the exotic partners of the $Z_c(3900)$ in the charmonium spectrum.

    ↳ hep-phnucl-exnucl-thPRD(2019)·20 citations
11. 11*

    First extraction of the scalar proton dynamical polarizabilities from real Compton scattering data

    B. Pasquini (1, 2)🇮🇹 · P. Pedroni (2)🇮🇹 · S. Sconfietti (1, 2) ((1) U. Pavia, (2) INFN, Pavia)🇮🇹

    We present the first attempt to extract the scalar dipole dynamical polarizabilities from proton real Compton scattering data below pion-production threshold. The theoretical framework combines dispersion relations technique, low-energy expansion and multipole decomposition of the scattering amplitudes. The results are obtained with statistical tools that have never been applied so far to Compton scattering data and are crucial to overcome problems inherent to the analysis of the available data set.

    ↳ hep-phhep-exnucl-exnucl-thPRC(2018)·27 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.