Nuclear Theory·nucl-th

Wednesday·October 9, 2019

12 papers—5 primary·7 cross-listed

01
Color Correlations in the Proton
Gerald A. Miller🇺🇸
A general QCD light front formalism to compute many-body color charge correlation functions due to quarks in the proton was constructed~\cite{Dumitru:2018vpr}. These enable new studies of color charge distributions in the nucleon. The analogies between such correlation functions to electric and magnetization charge densities in the proton and also to nucleon-nucleon correlations in the nucleus are discussed. Including the color charge correlations leads naturally to the removal of infrared divergences that occurs in two- and three-gluon exchange interactions in $q q ˉ$ -proton scattering. Extensions to include gluonic color charge correlations are discussed.
nucl-thhep-ph0 citations
02
Density-dependent NN-interaction from subsubleading chiral 3N-force: Intermediate-range contributions
N. Kaiser🇩🇪
From the subsubleading chiral three-nucleon force [intermediate-range contributions, published in Phys. Rev. C\,87, 054007 (2013)] a density-dependent NN-interaction $V_{med}$ is derived in isospin-symmetric nuclear matter. Following the division of the pertinent 3N-diagrams into two-pion-one-pion exchange topology and ring topology, one evaluates for these all selfclosings and concatenations of nucleon-lines to an in-medium loop. In the case of the $2 π 1 π$ -exchange topology, the momentum- and $k_{f}$ -dependent potentials associated with the isospin-operators ( $1$ and $τ_{1} \cdot τ_{2}$ ) and five independent spin-structures require at most one numerical integration. For the more challenging (concatenations of the) ring diagrams proportional to $c_{1, 2, 3, 4}$ , one ends up with regularized double-integrals $\int_{0}^{λ} d r r \int_{0}^{π /2} d ψ$ from which the $λ^{2}$ -divergence has been subtracted and the logarithmic piece $\sim ln (m_{π} / λ)$ is isolated. The derived semi-analytical results are most helpful to implement the subsubleading chiral 3N-forces into nuclear many-body calculations.
nucl-thPRC(2020)·10 citations
03
Time-Reversal-Invariance Violation in the $N d$ System and Large- $N_{C}$
Jared Vanasse🇺🇸 · Anna C. Bowman🇺🇸
A minimal set of five low energy constants (LECs) for time-reversal and parity violating ( $\neq T \neq P$ ) nucleon-nucleon ( $N N$ ) interactions at low energies ( $E < m_{π}^{2} / M_{N}$ ) is given. Using a large- $N_{C}$ (number of colors in QCD) analysis we show that one linear combination of LECs is $O (N_{C})$ , three LECs are $O (N_{C}^{0})$ , and one linear combination of LECs is $O (N_{C}^{- 1})$ . We also calculate the $\neq T \neq P$ observables of neutron spin rotation through a polarized deuteron target and a spin correlation coefficient in nucleon-deuteron scattering using pionless effective field theory. Using the large- $N_{C}$ analysis we show that the spin correlation coefficient and the neutron spin rotation are predominantly determined by same two LECs in the large- $N_{C}$ basis.
nucl-thPRC(2023)·10 citations
04
Unblocking of stellar electron capture for neutron-rich $N = 50$ nuclei at finite temperature
Alan A. Dzhioev · K. Langanke · G. Martínez-Pinedo · A. I. Vdovin · Ch. Stoyanov
We have calculated electron capture rates for neutron-rich $N = 50$ nuclei ( $^{78}$ Ni, $^{82}$ Ge, $^{86}$ Kr, $^{88}$ Sr) within the Thermal QRPA approach at temperatures $T = 0$ , corresponding to capture on the ground-state, and at $T = 10$ GK (0.86 MeV), which is a typical temperature at which the $N = 50$ nuclei are abundant during a supernova collapse. In agreement with recent experiments, we find no Gamow-Teller (GT $_{+}$ ) strength at low excitation energies, $E < 7$ MeV, caused by Pauli blocking induced by the $N = 50$ shell gap. At the astrophysically relevant temperatures this Pauli blocking of the GT $_{+}$ strength is overcome by thermal excitations across the $Z = 40$ proton and $N = 50$ neutron shell gaps, leading to a sizable GT contribution to the electron capture. At the high densities, at which the $N = 50$ nuclei are important for stellar electron capture, forbidden transitions contribute noticeably to the capture rate. Our results indicate that the neutron-rich $N = 50$ nuclei do not serve as an obstacle of electron capture during the supernova collapse.
nucl-thPRC(2020)·34 citations
05
Lifetime estimations and a non-monotonic initial energy density in heavy ion collisions at RHIC and LHC
G. Kasza🇭🇺 · T. Csorgo🇭🇺
We highlight some connections between the final state hadronic observables and the initial conditions using a recently found new exact family of solutions of relativistic hydrodynamics. These relations provide explicit examples of the scaling behaviour in relativistic hydrodynamics and may provide an advanced estimate of the lifetime and the initial energy density in $s_{N N} = 62.4$ , $130$ , and $200$ GeV Au+Au collisions at RHIC and $s_{N N} = 5.0$ TeV Pb+Pb and $5.44$ TeV Xe+Xe as well as $s = 7$ , $8$ and $13$ TeV p+p collisions at LHC energies. A surprising result is that these advanced estimates yield a non-monotonic increase of the initial energy density with increasing collision energy at the RHIC energy range.
nucl-thhep-exhep-phnucl-exPhys.Part.Nucl.(2020)·0 citations
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 $e p$ 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 $e p$ scattering at HERA can be very well described by any of the four variants. When going from $e p$ 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
07
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
08
20Ne + 76Ge elastic and inelastic scattering at 306 MeV
A. Spatafora🇮🇹 · F. Cappuzzello🇮🇹 · D. Carbone🇮🇹 · M. Cavallaro🇮🇹 · J. A. Lay🇪🇸 · L. Acosta🇲🇽 · C. Agodi🇮🇹 · D. Bonanno🇮🇹 · D. Bongiovanni🇮🇹 · I. Boztosun🇹🇷 · G. A. Brischetto🇮🇹 · S. Burrello🇮🇹 and 37 other authors
Background: Double charge exchange (DCE) nuclear reactions have recently attracted much interest as tools to provide experimentally driven information about nuclear matrix elements of interest in the context of neutrinoless double-beta decay. In this framework, a good description of the reaction mechanism and a complete knowledge of the initial and final-state interactions are mandatory. Presently, not enough is known about the details of the optical potentials and nuclear response to isospin operators for many of the projectile-target systems proposed for future DCE studies. Among these, the 20Ne + 76Ge DCE reaction is particularly relevant due to its connection with 76Ge double-beta decay. Purpose: We intend to characterize the initial-state interaction for the 20Ne + 76Ge reactions at 306 MeV bombarding energy and determine the optical potential and the role of the couplings between elastic channel and inelastic transitions to the first low-lying excited states. Methods: We determine the experimental elastic and inelastic scattering cross-section angular distributions, compare the theoretical predictions by adopting different models of optical potentials with the experimental data, and evaluate the coupling effect through the comparison of the distorted-wave Born approximation calculations with the coupled channels ones. Results: Optical models fail to describe the elastic angular distribution above the grazing angle (9.4{\deg}). A correction in the geometry to effectively account for deformation of the involved nuclear systems improves the agreement up to about 14{\deg}. Coupled channels effects are crucial to obtain good agreement at large angles in the elastic scattering cross section.
↳ nucl-exnucl-thPRC(2019)·49 citations
09
Khuri-Treiman equations for $3 π$ decays of particles with spin
JPAC Collaboration: M. Albaladejo🇺🇸 · D. Winney🇺🇸 · I. V.~Danilkin🇩🇪 · C. Fernandez-Ramirez🇲🇽 · V. Mathieu🇪🇸 · M. Mikhasenko🇨🇭 · A. Pilloni🇮🇹 · J.A. Silva-Castro🇲🇽 · A. P. Szczepaniak🇺🇸
Khuri-Treiman equations have proven to be a useful theoretical tool in the analysis of 3-body decays, specially into the $3 π$ final state. In this work we present in full detail the necessary generalization of the formalism to study the decays of particles with arbitrary spin, parity, and charge conjugation. To this extent, we find it most convenient to work with helicity amplitudes instead of the so-called invariant amplitudes, specially when dealing with the unitarity relations. The isobar expansions in the three possible ( $s$ -, $t$ -, and $u$ -) final channels are related with the appropriate crossing matrices. We pay special attention to the kinematical singularities and constraints of the helicity amplitudes, showing that these can be derived by means of the crossing matrix.
↳ hep-phhep-exhep-thnucl-thPRD(2020)·25 citations
10
Spin polarizations under a pseudovector interaction between quarks with the Kobayashi-Maskawa-'t Hooft term in high density quark matter
M. Morimoto (Kochi Univ., Japan)🇯🇵 · Y. Tsue (Kochi Univ., Japan)🇵🇹 · J. da Providencia (Univ. de Coimbra, Portugal)🇵🇹 · C. Providencia (Univ. de Coimbra, Portugal) · M. Yamamura (Kansai Univ., Japan)🇵🇹
A possibility of a quark spin polarization originated from a pseudovector condensate is investigated in the three-flavor Nambu-Jona-Lasinio model with the Kobayashi-Maskawa-'t Hooft interaction which leads to flavor mixing. It is shown that a pseudovector condensate related to the strange quark easily occurs compared with pseudovector condensate related to light quarks. Further, it is shown that the pseudovector condensate related to the strange quark appears at a slightly small chemical potential by the effect of the flavor mixing due to the Kobayashi-Maskawa-'t Hooft interaction.
↳ hep-phnucl-thIJMPE(2020)·2 citations
11
Accessing the gluonic structure of light nuclei at the Electron Ion Collider
Heikki Mäntysaari🇫🇮 · Björn Schenke🇺🇸
We show how exclusive vector meson production off light ions can be used to probe the spatial distribution of small- $x$ gluons in the deuteron and $^{3}$ He wave functions. In particular, we demonstrate how short range repulsive nucleon-nucleon interactions affect the predicted coherent $J /Ψ$ production spectra. Fluctuations of the nucleon substructure are shown to have a significant effect on the incoherent cross section above $∣ t ∣ ≳ 0.2 GeV^{2}$ . By explicitly performing the JIMWLK evolution, we predict the $x$ -dependence of coherent and incoherent cross sections in the EIC energy range. Besides the increase of the average size of the nucleus with decreasing $x$ , both the growth of the nucleons and subnucleonic hot spots are visible in the cross sections. The decreasing length scale of color charge fluctuations with decreasing $x$ is also present, but may not be observable for $∣ t ∣ < 1 GeV^{2}$ , if subnucleonic spatial fluctuations are present.
↳ hep-phnucl-thPRC(2020)·34 citations
12
The Partonic Content of Nucleons and Nuclei
Juan Rojo🇳🇱
Deepening our knowledge of the partonic content of nucleons and nuclei represents a central endeavour of modern high-energy and nuclear physics, with ramifications in related disciplines such as astroparticle physics. There are two main scientific drivers motivating these investigations of the partonic structure of hadrons. On the one hand, addressing fundamental open issues in our understanding in the strong interactions such as the origin of the nucleon mass, spin, and transverse structure; the presence of heavy quarks in the nucleon wave function; and the possible onset of novel gluon-dominated dynamical regimes. On the other hand, pinning down with the highest possible precision the substructure of nucleons and nuclei is a central component for theoretical predictions in a wide range of experiments, from proton and heavy ion collisions at the Large Hadron Collider to ultra-high energy neutrino interactions at neutrino telescopes. This Article presents a succinct non-technical overview of our modern understanding of the quark, gluon, and photon substructure of nucleons and nuclei, focusing on recent trends and results and discussing future perspectives for the field.
↳ hep-phhep-exnucl-thOxford Research Encyclopedia of Physics(2021)·16 citations

Affiliations

first authorsco-authorsvia INSPIRE