Nuclear Theory·nucl-th

Tuesday·February 13, 2018

11 papers—6 primary·5 cross-listed

07
Gauge Invariant Noether's Theorem and The Proton Spin Crisis
Gouranga C Nayak🇺🇸
Due to proton spin crisis it is necessary to understand the gauge invariant definition of the spin and orbital angular momentum of the quark and gluon from first principle. In this paper we derive the gauge invariant Noether's theorem by using combined Lorentz transformation plus local gauge transformation. We find that the notion of the gauge invariant definition of the spin (or orbital) angular momentum of the electromagnetic field does not exist in Dirac-Maxwell theory although the notion of the gauge invariant definition of the spin (or orbital) angular momentum of the electron exists. We find that the gauge invariant definition of the spin angular momentum of the electromagnetic field in the literature is not correct because of the non-vanishing surface term in Dirac-Maxwell theory although the corresponding surface term vanishes for linear momentum. We also show that the Belinfante-Rosenfeld tensor is not required to obtain symmetric and gauge invariant energy momentum tensor of the electron and the electromagnetic field in Dirac-Maxwell theory.
↳ hep-phnucl-thJHEP(2018)·7 citations
08
Determination of $s$ - and $p$ -wave $I = 1/2$ $K π$ scattering amplitudes in $N_{f} = 2 + 1$ lattice QCD
Ruairí Brett🇺🇸 · John Bulava🇩🇰 · Jacob Fallica🇺🇸 · Andrew Hanlon🇩🇪 · Ben Hörz🇩🇪 · Colin Morningstar🇺🇸
The elastic $I = 1/2$ , $s$ - and $p$ -wave kaon-pion scattering amplitudes are calculated using a single ensemble of anisotropic lattice QCD gauge field configurations with $N_{f} = 2 + 1$ flavors of dynamical Wilson-clover fermions at $m_{π} = 230 MeV$ . A large spatial extent of $L = 3.7 fm$ enables a good energy resolution while partial wave mixing due to the reduced symmetries of the finite volume is treated explicitly.The $p$ -wave amplitude is well described by a Breit-Wigner shape with parameters $m_{K^{*}} / m_{π} = 3.808 (18)$ and $g_{K^{*} K π}^{BW} = 5.33 (20)$ which are insensitive to the inclusion of $d$ -wave mixing and variation of the $s$ -wave parametrization. An effective range description of the near-threshold $s$ -wave amplitude yields $m_{π} a_{0} = - 0.353 (25)$ .
↳ hep-lathep-phnucl-thNPB(2018)·82 citations
09
Correspondence between the physics of extremal black holes and that of stable heavy atomic nuclei
B. P. Kosyakov🇷🇺 · E. Yu. Popov🇷🇺 · M. A. Vronsky🇷🇺
Extremal black holes are immune of Hawking evaporation. On the other hand, some heavy atomic nuclei feature extraordinary stability to spontaneous transmutations changing their mass numbers. The fact that extremal black holes and stable nuclei share a common trait, that of defying spontaneous ejection of their constituents, suggests that a good part of nuclear physics is modelled on physics of extremal black holes through a simple version of gauge/gravity duality. A general criterion for discriminating between stable and unstable microscopic systems can be formulated to gain a new insight into some imperfectly understood phenomena, such as instability of truly neutral spinless particles (Higgs bosons, $π_{0}$ , quarkonia, glueballs).
↳ hep-thgr-qchep-phnucl-thClass.Quant.Grav.(2019)·4 citations
10
Radial Distributions of Power and Isotopic Concentrations in Candidate Accident Tolerant Fuel U3Si2 and UO2/U3Si2 Fuel Pins with FeCrAl Cladding
Shengli Chen🇨🇳 · Cenxi Yuan🇨🇳 · Daxi Guo🇨🇳
Monte Carlo simulations show similarity on radial distributions of power and isotopic concentrations at any effective full power depletion time among five kinds of fuel-cladding combinations with the same cycle length, including the normal UO2-zircaloy combination, the candidate Accident Tolerant Fuel (ATF) UO2/U3Si2-FeCrAl combination, and three kinds of candidate ATF U3Si2-FeCrAl combinations. An analytical formula f(x,s) including the fuel exposure (s) and the relative radial (x) is proposed to describe the radial properties for all five kinds of fuel-cladding combinations. f(x,s) has the form of the second order polynomial term of s with the exponential type of coefficients depending on x. It is shown that the suggested function f(x,s) gives a nice description on the simulation data with rather small deviations and can immediately provide radial distribution of power, burnup, and isotopic concentrations of 235U, 238U, 239Pu, and 241Pu at any fuel exposure and relative radius. It is useful to discuss the fuel temperature through the present analytical formula. The realistic radial power distribution gives flatter radial temperature distribution compared with the uniform power distribution. Because of the different thermal conductivities of fuels and claddings and the different thicknesses of claddings, the present discussed five kinds of fuel-cladding combinations have different radial temperature distributions, although their radial power distributions are quite similar. The present work provides an analytical formula to describe the radial properties of the ATF which is expected to be helpful for further neutronic and multi-physics coupling studies.
↳ physics.app-phnucl-thAnnals Nucl.Energy(2019)·2 citations
11
The $B = 5$ Skyrmion as a two-cluster system
Sven Bjarke Gudnason🇨🇳 · Chris Halcrow🇨🇳
The classical $B = 5$ Skyrmion can be approximated by a two-cluster system where a $B = 1$ Skyrmion is attached to a core $B = 4$ Skyrmion. We quantise this system, allowing the $B = 1$ to freely orbit the core. The configuration space is 11-dimensional but simplifies significantly after factoring out the overall spin and isospin degrees of freedom. We exactly solve the free quantum problem and then include an interaction potential between the Skyrmions numerically. The resulting energy spectrum is compared to the corresponding nuclei -- the Helium-5/Lithium-5 isodoublet. We find approximate parity doubling not seen in the experimental data. In addition, we fail to obtain the correct ground state spin. The framework laid out for this two-cluster system can readily be modified for other clusters and in particular for other $B = 4 n + 1$ nuclei, of which the $B = 5$ is the simplest example.
↳ hep-thnucl-thPRD(2018)·11 citations

Affiliations

first authorsco-authorsvia INSPIRE

Gauge Invariant Noether's Theorem and The Proton Spin Crisis

Determination of s- and p-wave I=1/2 Kπ scattering amplitudes in Nf​=2+1 lattice QCD

Correspondence between the physics of extremal black holes and that of stable heavy atomic nuclei

Radial Distributions of Power and Isotopic Concentrations in Candidate Accident Tolerant Fuel U3Si2 and UO2/U3Si2 Fuel Pins with FeCrAl Cladding

The B=5 Skyrmion as a two-cluster system

Affiliations

Determination of $s$ - and $p$ -wave $I = 1/2$ $K π$ scattering amplitudes in $N_{f} = 2 + 1$ lattice QCD

The $B = 5$ Skyrmion as a two-cluster system