Nuclear Theory·nucl-th

Friday·September 2, 2016

5 papers—1 primary·4 cross-listed

01
[Submitted on 1 Sept 2016]
Charge symmetry breaking in $Λ$ hypernuclei: updated HYP 2015 progress report
Avraham Gal🇮🇱
Ongoing progress in understanding and evaluating charge symmetry breaking in $Λ$ hypernuclei is discussed in connection to recent measurements of the $_{Λ}^{4} H (0_{g.s.}^{+})$ binding energy at MAMI [A1 Collaboration: PRL 114 (2015) 232501] and of the $_{Λ}^{4} He (1_{exc}^{+})$ excitation energy at J-PARC [E13 Collaboration: PRL 115 (2015) 222501].
Comments:
updated version of HYP 2015 invited talk; a slightly edited v2 to be published in the Japan Physical Society Conference Proceedings
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
1609.00229 [pdf]
JPS Conf.Proc.(2017)·2 citations
02
[Submitted on 31 Aug 2016] (cross-list from hep-th)
Thermal chiral vortical and magnetic waves: new excitation modes in chiral fluids
Tigran Kalaydzhyan🇺🇸 · Elena Murchikova🇺🇸
In certain circumstances, chiral (parity-violating) medium can be described hydrodynamically as a chiral fluid with microscopic quantum anomalies. Possible examples of such systems include strongly coupled quark-gluon plasma, liquid helium 3He-A, neutron stars and the Early Universe. We study first-order hydrodynamics of a chiral fluid on a vortex background and in an external magnetic field. We show that there are two previously undiscovered modes describing heat waves propagating along the vortex and magnetic field. We call them the Thermal Chiral Vortical Wave and Thermal Chiral Magnetic Wave. We also identify known gapless excitations of density (chiral vortical and chiral magnetic waves) and transverse velocity (chiral Alfven wave). We demonstrate that the velocity of the chiral vortical wave is zero, when the full hydrodynamic framework is applied, and hence the wave is absent and the excitation reduces to the charge diffusion mode. We also comment on the frame-dependent contributions to the obtained propagation velocities.
Comments:
5 pages. Version to appear in Nucl. Phys. B
Subjects:
High Energy Physics — Theory (hep-th); Mesoscale and Nanoscale Physics (cond-mat.mes-hall); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1609.00024 [pdf]
NPB(2017)·17 citations
03
[Submitted on 24 Aug 2016] (cross-list from cond-mat.str-el)
Overscreened Kondo effect, (color) superconductivity and Shiba states in Dirac metals and quark matter
Takuya Kanazawa🇯🇵 · Shun Uchino🇯🇵
We study the interplay between the Kondo effect and (color) superconductivity in doped Dirac metals with magnetic impurities and in quark matter with colorful impurities. We first point out that the overscreened Kondo effect arises in the normal state of these systems. Next the (color) superconducting gap is incorporated as a mean field and the phase diagram for a varying gap and temperature is constructed nonperturbatively. A rich phase structure emerges from a competition of effects unique to a multichannel system. The Kondo-screened phase is shown to disappear for a sufficiently large gap. Peculiarity of quark matter due to the confining property of non-Abelian gauge fields is noted. We also investigate the spectrum of sub-gap excited states, called Shiba states. Based on a model calculation and physical reasoning we predict that, as the coupling of the impurity to the bulk is increased, there will be more than one quantum phase transition due to level crossing among overscreened states.
Comments:
25 pages, 15 figures. v2: Figure 9 added, minor revisions. matches published version
Subjects:
Strongly Correlated Electrons (cond-mat.str-el); Superconductivity (cond-mat.supr-con); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1609.00033 [pdf]
PRD(2016)·24 citations
04
[Submitted on 1 Sept 2016] (cross-list from nucl-ex)
Alpha clustering in $^{28}$ Si probed through the identification of high-lying $0^{+}$ states
P. Adsley · D.G. Jenkins · J. Cseh · S.S. Dimitriova · J.W. Brümmer · K.C.W. Li · D.J. Marín-Lámbarri · K. Lukyanov · N.Y. Kheswa · R. Neveling · P. Papka · L. Pellegri and 6 other authors
Aspects of nuclear structure in alpha-conjugate nuclei have long been associated with alpha clustering, including the existence of superdeformed bands. In this paper, an alpha-particle inelastic scattering experiment investigating the location of $0^{+}$ states in $^{28}$ Si is reported in an attempt to locate possible cluster states. The results are compared to a semi-microscopic model which shows good agreement with the data, and supports the assignment of a newly discovered $0^{+}$ state as the band-head of a previously observed superdeformed band in $^{28}$ Si
Comments:
6 figures, 8 pages, updated to fix broken figure placement, updated again to fix a couple of typos; final update
Subjects:
Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
1609.00296 [pdf]
PRC(2017)·21 citations
05
[Submitted on 1 Sept 2016] (cross-list from cond-mat.quant-gas)
Towards Quantum Turbulence in Cold Atomic Fermionic Superfluids
Aurel Bulgac · Michael McNeil Forbes · Gabriel Wlazłowski
Fermionic superfluids provide a new realization of quantum turbulence, accessible to both experiment and theory, yet relevant to phenomena from both cold atoms to nuclear astrophysics. In particular, the strongly interacting Fermi gas realized in cold-atom experiments is closely related to dilute neutron matter in neutron star crusts. Unlike the liquid superfluids 4He (bosons) and 3He (fermions) where quantum turbulence has been studied in the laboratory, superfluid Fermi gases stand apart for a number of reasons. They admit a reliable theoretical description based on a DFT called the TDSLDA that describes both static and dynamic phenomena. Cold atom experiments demonstrate exquisite control over particle number, spin polarization, density, temperature, and interaction strength. Topological defects such as domain walls and quantized vortices, which lie at the heart of quantum turbulence, can be created and manipulated with time-dependent external potentials, and agree with the time-dependent theoretical techniques. While similar experimental and theoretical control exists for weakly interacting Bose gases, the unitary Fermi gas is strongly interacting. The resulting vortex line density is extremely high, and quantum turbulence may thus be realized in small systems where classical turbulence is suppressed. Fermi gases also permit the study of exotic superfluid phenomena such as a 3D LOFF supersolid, and a finite temperature pseudo-gap in the regime of classical turbulence. The dynamics associated with these phenomena has only started to be explored. Finally, superfluid mixtures have recently been realized, providing experimental access to phenomena like Andreev-Bashkin entrainment. Superfluid Fermi gases thus provide a rich forum for addressing phenomena related to quantum turbulence with applications ranging from terrestrial superfluidity to astrophysical dynamics in neutron stars.
Comments:
12 pages, 5 figures: Updated to correspond with published version (minor updates, 1 new figure comparing theory and experiment)
Subjects:
Quantum Gases (cond-mat.quant-gas); Nuclear Theory (nucl-th)
arXiv:
1609.00363 [pdf]
J.Phys.B(2016)·16 citations

Affiliations

first authorsco-authorsvia INSPIRE

Charge symmetry breaking in Λ hypernuclei: updated HYP 2015 progress report

Thermal chiral vortical and magnetic waves: new excitation modes in chiral fluids

Overscreened Kondo effect, (color) superconductivity and Shiba states in Dirac metals and quark matter

Alpha clustering in 28Si probed through the identification of high-lying 0+ states

Towards Quantum Turbulence in Cold Atomic Fermionic Superfluids

Affiliations

Charge symmetry breaking in $Λ$ hypernuclei: updated HYP 2015 progress report

Alpha clustering in $^{28}$ Si probed through the identification of high-lying $0^{+}$ states