Nuclear Theory·nucl-th

Monday·July 1, 2019

9 papers—5 primary·4 cross-listed

01
Elastic Antiproton-Nucleus Scattering from Chiral Forces
Matteo Vorabbi🇨🇦 · Michael Gennari🇨🇦 · Paolo Finelli🇮🇹 · Carlotta Giusti🇮🇹 · Petr Navrátil🇨🇦
Elastic scattering of antiprotons off $^{4}$ He, $^{12}$ C, and $^{16, 18}$ O is described for the first time with a totally microscopic approach based on the calculation of an optical potential (OP) describing the antiproton-target interaction. The OP is derived using the recent antiproton-nucleon ( $p ˉ N$ ) chiral interaction to calculate the $p ˉ N$ $t$ matrix, while the target densities are computed with the ab initio no-core shell model using chiral interactions as well. Our results are in a good agreement with the existing experimental data and the results computed at different chiral orders of the $p ˉ N$ interaction display the convergence pattern expected from the theory.
nucl-thnucl-exPRL(2020)·15 citations
02
Nuclear effective field theory: status and perspectives
H.-W. Hammer🇩🇪 · S. König🇩🇪 · U. van Kolck🇫🇷
The nuclear physics landscape has been redesigned as a sequence of effective field theories (EFTs) connected to the Standard Model through symmetries and lattice simulations of Quantum Chromodynamics (QCD). EFTs in this sequence are expansions around different low-energy limits of QCD, each with its own characteristics, scales, and ranges of applicability regarding energy and number of nucleons. We review each of the three main nuclear EFTs -- Chiral, Pionless, Halo/Cluster -- highlighting their similarities, differences, and connections. In doing so, we survey the structural properties and reactions of nuclei that have been derived from the ab initio solution of the few- and many-body problem built upon EFT input.
nucl-thRMP(2020)·569 citations
03
Number conserving particle-hole RPA for superfluid nuclei
J. Dukelsky🇪🇸 · J.E. García-Ramos🇪🇸 · J.M. Arias🇪🇸 · P. Pérez-Fernández🇪🇸 · P. Schuck🇫🇷
We present a number conserving particle-hole RPA theory for collective excitations in the transition from normal to superfluid nuclei. The method derives from an RPA theory developed long ago in quantum chemistry using antisymmetric geminal powers, or equivalently number projected HFB states, as reference states. We show within a minimal model of pairing plus monopole interactions that the number conserving particle-hole RPA excitations evolve smoothly across the superfluid phase transition close to the exact results, contrary to particle-hole RPA in the normal phase and quasiparticle RPA in the superfluid phase that require a change of basis at the broken symmetry point. The new formalism can be applied in a straightforward manner to study particle-hole excitations on top of a number projected HFB state.
nucl-thPLB(2019)·5 citations
04
Suppression of elliptic flow without viscosity
Adam Takacs🇳🇴 · Denes Molnar🇭🇺
We investigate fluid-to-particle conversion using the usual Cooper-Frye approach but with more general local equilibrium distributions than the Boltzmann or Bose/Fermi distributions typically used. Even though we study ideal fluids (i.e., shear stress and bulk pressure are zero everywhere), we find a suppression of elliptic flow (v2) at high transverse momenta (pT>1.5 GeV/c), relative to results obtained with the traditional Boltzmann distributions. The non-viscous suppression shows qualitatively similar features to the well-known shear viscous suppression of v2; for example, it increases with pT, and it is smaller for heavier species as seen in self-consistent kinetic theory calculations. Our results question whether all of the v2 suppression seen in the data can be attributed to viscous effects, and indicate that shear viscosities extracted from RHIC and LHC elliptic flow data might be overestimated.
nucl-thhep-exhep-phnucl-ex8 citations
05
How AMPT generates large elliptic flow with small cross sections
Denes Molnar (Dept. of Physics and Astronomy, Purdue University, West Lafayette, IN)🇺🇸
We resolve the long-standing open question of how the transport model AMPT manages to generate sufficiently high elliptic flow (v2) in A+A reactions with only few-millibarn 2->2 partonic cross sections - in apparent contradiction with an early study by Molnar and Gyulassy. Through detailed comparisons with the covariant Molnar's Parton Cascade (MPC), we pinpoint which features of initial conditions, interactions, and dynamics encoded in the partonic stage of AMPT allow it to circumvent the "opacity puzzle" at RHIC.
nucl-thhep-phnucl-ex9 citations
06
Nonperturbative Corrections to Soft Drop Jet Mass
André H. Hoang🇦🇹 · Sonny Mantry🇺🇸 · Aditya Pathak🇦🇹 · Iain W. Stewart🇺🇸
We provide a quantum field theory based description of the nonperturbative effects from hadronization for soft drop groomed jet mass distributions using the soft-collinear effective theory and the coherent branching formalism. There are two distinct regions of jet mass $m_{J}$ where grooming modifies hadronization effects. In a region with intermediate $m_{J}$ an operator expansion can be used, and the leading power corrections are given by three universal nonperturbative parameters that are independent of all kinematic variables and grooming parameters, and only depend on whether the parton initiating the jet is a quark or gluon. The leading power corrections in this region cannot be described by a standard normalized shape function. These power corrections depend on the kinematics of the subjet that stops soft drop through short distance coefficients, which encode a perturbatively calculable dependence on the jet transverse momentum, jet rapidity, and on the soft drop grooming parameters $z_{cut}$ and $β$ . Determining this dependence requires a resummation of large logarithms, which we carry out at LL order. For smaller $m_{J}$ there is a nonperturbative region described by a one-dimensional shape function that is unusual because it is not normalized to unity, and has a non-trivial dependence on $β$ .
↳ hep-phnucl-thJHEP(2019)·74 citations
07
$D K$ , $D D K$ , and $D D D K$ molecules--understanding the nature of the $D_{s 0}^{*} (2317)$
Tian-Wei Wu🇨🇳 · Ming-Zhu Liu🇨🇳 · Li-Sheng Geng🇨🇳 · Emiko Hiyama🇯🇵 · Manuel Pavon Valderrama🇨🇳
The $D K$ interaction is strong enough to form a bound state, the $D_{s 0}^{*} (2317)$ . This in turn begs the question of whether there are bound states composed of several charmed mesons and a kaon. Previous calculations indicate that the three-body $D D K$ system is probably bound, where the quantum numbers are $J^{P} = 0^{-}$ , $I = \frac{1}{2}$ , $S = 1$ and $C = 2$ . The minimum quark content of this state is $cc q ˉ s ˉ$ with $q = u, d$ , which means that, if discovered, it will be an explicitly exotic tetraquark. In the present work. we apply the Gaussian Expansion Method to study the $D D D K$ system and show that it binds as well. The existence of these three and four body states is rather robust with respect to the $D D$ interaction and subleading (chiral) corrections to the $D K$ interaction. If these states exist, it is quite likely that their heavy quark symmetry counterparts exist as well. These three-body $D D K$ and four-body $D D D K$ molecular states could be viewed as counterparts of atomic nuclei, which are clusters of nucleons bound by the residual strong force, or chemical molecules, which are clusters of atoms bound by the residual electromagnetic interaction.
↳ hep-phhep-exhep-latnucl-ex+1PRD(2019)·68 citations
08
30 years of jet quenching
Xin-Nian Wang🇨🇳
In the last 30 years, the physics of jet quenching has gone from an early stage of a pure theoretical idea to initial theoretical calculations, experimental verification and now a powerful diagnostic tool for studying properties of the quark-gluon plasma (QGP) in high-energy heavy-ion collisions. I will describe my collaboration with Miklos Gyulassy in this exciting area of high-energy nuclear physics in the past 30 years on this special occasion of his 70th birthday and discuss what is ahead of us in jet tomographic study of QGP in heavy-ion collisions.
↳ hep-phnucl-thPoS(2020)·5 citations
09
Kinetic approach to a relativistic BEC with inelastic processes
Richard Lenkiewicz🇩🇪 · Alex Meistrenko🇩🇪 · Hendrik van Hees🇩🇪 · Kai Zhou🇩🇪 · Zhe Xu🇨🇳 · Carsten Greiner🇩🇪
The phenomenon of Bose-Einstein condensation is investigated in the context of the Color-Glass-Condensate description of the initial state of ultrarelativistic heavy-ion collisions. For the first time, in this paper we study the influence of particle-number changing $2 \leftrightarrow 3$ processes on the transient formation of a Bose-Einstein Condensate within an isotropic system of scalar bosons by including $2 \leftrightarrow 3$ interactions of massive bosons with constant and isotropic cross sections, following a Boltzmann equation. The one-particle distribution function is decomposed in a condensate part and a non-zero momentum part of excited modes, leading to coupled integro-differential equations for the time evolution of the condensate and phase-space distribution function, which are then solved numerically. Our simulations converge to the expected equilibrium state, and only for $σ_{23} / σ_{22} ≪ 1$ we find that a Bose-Einstein condensate emerges and decays within a finite lifetime in contrast to the case where only binary scattering processes are taken into account, and the condensate is stable due to particle-number conservation. Our calculations demonstrate that Bose-Einstein Condensates in the very early stage of heavy-ion collisions are highly unlikely, if inelastic collisions are significantly participating in the dynamical gluonic evolution.
↳ hep-phnucl-thPRD(2019)·6 citations

Affiliations

first authorsco-authorsvia INSPIRE