Nuclear Theory·nucl-th

Thursday·June 15, 2017

4 papers—3 primary·1 cross-listed

01
Finite temperature pairing re-entrance in drip-line $^{48}$ Ni nucleus
M. Belabbas🇩🇿 · J.J. Li🇨🇳 · J. Margueron🇺🇸
Finite-temperature Hartree-Fock-Bogoliubov theory using Skyrme interactions and Relativistic Hartree-Fock effective Lagrangians, predicts $^{48}$ Ni as being a possible candidate for the finite temperature pairing re-entrance phenomenon. For this proton-drip-line nucleus, proton resonant states are expected to contribute substantially to pairing correlations and the two predicted critical temperatures are $T_{c 1} \sim 0.08 - 0.2$ ~MeV and $T_{c 2} \sim 0.7 - 0.9$ ~MeV. It is also shown that pairing re-entrance modifies the proton single particle energies around the Fermi level, as well as occupation numbers, and quasi-particle levels. The understanding of pairing re-entrance in $^{48}$ Ni presently challenge our understanding of exotic matter under extreme conditions.
nucl-thPRC(2017)·9 citations
02
Small- $x$ Asymptotics of the Gluon Helicity Distribution
Yuri V. Kovchegov🇺🇸 · Daniel Pitonyak🇺🇸 · Matthew D. Sievert🇺🇸
We determine the small- $x$ asymptotics of the gluon helicity distribution in a proton at leading order in perturbative QCD at large $N_{c}$ . To achieve this, we begin by evaluating the dipole gluon helicity TMD at small $x$ . In the process we obtain an interesting new result: in contrast to the unpolarized dipole gluon TMD case, the operator governing the small- $x$ behavior of the dipole gluon helicity TMD is different from the operator corresponding to the polarized dipole scattering amplitude (used in our previous work to determine the small- $x$ asymptotics of the quark helicity distribution). We then construct and solve novel small- $x$ large- $N_{c}$ evolution equations for the operator related to the dipole gluon helicity TMD. Our main result is the small- $x$ asymptotics for the gluon helicity distribution: $Δ G \sim (\frac{1}{x})^{α_{h}^{G}}$ with $α_{h}^{G} = \frac{13}{4 3} \frac{α _{s} N _{c}}{2 π} \approx 1.88 \frac{α _{s} N _{c}}{2 π}$ . We note that the power $α_{h}^{G}$ is approximately 20 $%$ lower than the corresponding power $α_{h}^{q}$ for the small- $x$ asymptotics of the quark helicity distribution defined by $Δ q \sim (\frac{1}{x})^{α_{h}^{q}}$ with $α_{h}^{q} = \frac{4}{3} \frac{α _{s} N _{c}}{2 π} \approx 2.31 \frac{α _{s} N _{c}}{2 π}$ found in our earlier work.
nucl-thhep-exhep-phnucl-exJHEP(2017)·113 citations
03
Calculating the norm matrix to solve the A-body Schrödinger equation within a set of non-orthogonal many-body states
B. Bally · T. Duguet
There are efficient many-body methods, such as the (symmetry-restored) generator coordinate method in nuclear physics, that formulate the A-body Schrödinger equation within a set of nonorthogonal many-body states. Solving the corresponding secular equation requires the evaluation of the norm matrix and thus the capacity to compute its entries consistently and without any phase ambiguity. This is not always a trivial task, e.g. it remained a long-standing problem for methods based on general Bogoliubov product states. While a solution to this problem was found recently in Ref. [L. M. Robledo, Phys. Rev. C79, 021302 (2009)], the present work introduces an alternative method that can be generically applied to other classes of states of interest in many-body physics. The method is presently exemplified in the case of Bogoliubov states and numerically illustrated on the basis of a toy model.
nucl-thcond-mat.supr-conquant-ph0 citations
04
A revised $B (E 2; 2_{1}^{+} \to 0_{1}^{+})$ value in the semi-magic nucleus $^{210}$ Po
D. Kocheva · G. Rainovski · J. Jolie · N. Pietralla · A. Blazhev · A. Astier · Th. Braunroth · M.L. Cortés · A. Dewald · M. Djongolov · C. Fransen · K. Gladnishki and 20 other authors
The lifetimes of the $2_{1}^{+}$ , the $2_{2}^{+}$ and the $3_{1}^{-}$ states of $^{210}$ Po have been measured in the $^{208}$ Pb( $^{12}$ C, $^{10}$ Be) $^{210}$ Po transfer reaction by the Doppler-shift attenuation method. The results for the lifetime of the $2_{1}^{+}$ state is about three times shorter than the adopted value. However, the new value still does not allow for consistent description of the properties of the yrast $2_{1}^{+}$ , $4_{1}^{+}$ , $6_{1}^{+}$ , and $8_{1}^{+}$ states of $^{210}$ Po in the framework of nuclear shell models. The Quasi-particle Phonon Model (QPM) calculations also cannot overcome this problem thus indicating the existence of a peculiarity which is neglected in both theoretical approaches.
↳ nucl-exnucl-thEPJA(2017)·23 citations

Affiliations

first authorsco-authorsvia INSPIRE

Finite temperature pairing re-entrance in drip-line 48Ni nucleus

Small-x Asymptotics of the Gluon Helicity Distribution

Calculating the norm matrix to solve the A-body Schrödinger equation within a set of non-orthogonal many-body states

A revised B(E2;21+​→01+​) value in the semi-magic nucleus 210Po

Affiliations

Finite temperature pairing re-entrance in drip-line $^{48}$ Ni nucleus

Small- $x$ Asymptotics of the Gluon Helicity Distribution

A revised $B (E 2; 2_{1}^{+} \to 0_{1}^{+})$ value in the semi-magic nucleus $^{210}$ Po