Nuclear Theory·nucl-th

Thursday·June 16, 2016

11 papers—4 primary·7 cross-listed

05
[Submitted on 14 Jun 2016] (cross-list from cond-mat.quant-gas)
An effective-field-theory analysis of Efimov physics in heteronuclear mixtures of ultracold atomic gases
Bijaya Acharya · Chen Ji · Lucas Platter
We use an effective-field-theory framework to analyze the Efimov effect in heteronuclear three-body systems consisting of two species of atoms with a large interspecies scattering length. In the leading-order description of this theory, various three-body observables in heteronuclear mixtures can be universally parameterized by one three-body parameter. We present the next-to-leading corrections, which include the effects of the finite interspecies effective range and the finite intraspecies scattering length, to various three-body observables. We show that only one additional three-body parameter is required to render the theory predictive at this order. By including the effective range and intraspecies scattering length corrections, we derive a set of universal relations that connect the different Efimov features near the interspecies Feshbach resonance. Furthermore, we show that these relations can be interpreted in terms of the running of the three-body counterterms that naturally emerge from proper renormalization. Finally, we make predictions for recombination observables of a number of atomic systems that are of experimental interest.
Comments:
peer-reviewed and edited version, errors fixed
Subjects:
Quantum Gases (cond-mat.quant-gas); Nuclear Theory (nucl-th)
arXiv:
1606.04508 [pdf]
PRA(2016)·8 citations
06
[Submitted on 14 Jun 2016] (cross-list from hep-ph)
An electroweak basis for neutrinoless double $β$ decay
Michael L. Graesser🇺🇸
A discovery of neutrinoless double- $β$ decay would be profound, providing the first direct experimental evidence of $Δ L = 2$ lepton number violating processes. While a natural explanation is provided by an effective Majorana neutrino mass, other new physics interpretations should be carefully evaluated. At low--energies such new physics could manifest itself in the form of color and $S U (2)_{L} \times U (1)_{Y}$ invariant higher dimension operators. Here we determine a complete set of electroweak invariant dimension--9 operators, and our analysis supersedes those that only impose $U (1)_{e m}$ invariance. Imposing electroweak invariance implies: 1) a significantly reduced set of leading order operators compared to only imposing $U (1)_{e m}$ invariance; and 2) other collider signatures. Prior to imposing electroweak invariance we find a minimal basis of 24 dimension-9 operators, which is reduced to 11 electroweak invariant operators at leading order in the expansion in the Higgs vacuum expectation value. We set up a systematic analysis of the hadronic realization of the 4-quark operators using chiral perturbation theory, and apply it to determine which of these operators have long-distance pion enhancements at leading order in the chiral expansion. We also find at dimension--11 and dimension--13 the electroweak invariant operators that after electroweak symmetry breaking produce the remaining $Δ L = 2$ operators that would appear at dimension--9 if only $U (1)_{e m}$ is imposed.
Comments:
31 pages, 6 tables, 1 figure. v3 updated references and added extended introduction, conclusions unchanged from v2. v4: updated references; final published version
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
1606.04549 [pdf]
JHEP(2017)·75 citations
07
[Submitted on 15 Jun 2016] (cross-list from hep-ph)
$K ˉ$ -induced formation of the $f_{2} (1270)$ and $f_{2}^{^{'}} (1525)$ resonances on proton targets
Yin Huang🇨🇳 · Ju-jun Xie🇨🇳 · Jun He🇨🇳 · Xurong Chen🇨🇳 · Hong-fei Zhang🇨🇳
We investigate the productiong of $f_{2} (1270)$ and $f_{2}^{^{'}} (1525)$ mesons in the $K^{-} p \to Λ f_{2} (1270)$ , $K^{-} p \to Λ f_{2}^{^{'}} (1525)$ and $K^{-} p \to K^{+} K^{-} Λ$ reactions within an effective Lagrangian approach. For $K^{-} p \to f_{2} Λ$ reaction, by considering the contributions from the $t$ -channel $K^{+}$ exchange and $u$ -channel nucleon pole, we get a fairly good description of the experimental measurements about the total and differential cross sections. Based on the studies of the $K^{-} p \to f_{2} Λ$ reaction, we investigate $K^{-} p \to K^{+} K^{-} Λ$ reaction including the contributions from the $f_{2} (1270)$ and $f_{2}^{'} (1525)$ mesons decaying into $K^{+} K^{-}$ pair. The total cross sections and invariant mass distribution of the $K p \to K^{+} K^{-} Λ$ reaction are predicted. The results can be tested in future experiments and therefore offer new clues on the nature of these tensor states.
Comments:
6 pages,8 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
1606.04623 [pdf]
2 citations
08
[Submitted on 15 Jun 2016] (cross-list from hep-ph)
Instantaneous Bethe-Salpeter View of Goldstone-Type Pseudoscalar Mesons
Wolfgang Lucha🇦🇹 · Franz F. Schöberl🇦🇹
Describing the lightest pseudoscalar mesons as bound states of quark and antiquark within the framework of an instantaneous Bethe-Salpeter formalism constructed such as to retain (in contrast to Salpeter's equation) as much information on the relativistic effects provided by the full quark propagator as conceivable allows for a surprisingly simple implementation of their near masslessness mandatory for their interpretability as pseudo-Goldstone bosons related to the spontaneous breaking of the chiral symmetries of quantum chromodynamics.
Comments:
12 pages, 4 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1606.04781 [pdf]
Int.J.Mod.Phys.A(2016)·7 citations
09
[Submitted on 15 Jun 2016] (cross-list from hep-ph)
Energy versus centrality dependence of the jet quenching parameter $q^$ at RHIC and LHC: a new puzzle?
Carlota Andrés🇪🇸 · Néstor Armesto🇪🇸 · Matthew Luzum🇪🇸 · Carlos A. Salgado🇪🇸 · Pía Zurita🇪🇸
The central goal of jet quenching studies in high-energy nuclear collisions is the characterization of those QCD medium properties that are accessible by these probes. Most of the discussion in the last years has been focused on the determination of the jet quenching parameter, $q^$ . We present here an extraction of this parameter using data of inclusive particle suppression at RHIC and LHC energies for different centralities. Our approach consists of fitting a $K$ factor that quantifies the departure of this parameter from an ideal estimate, $K \equiv q^/ (2 ϵ^{3/4})$ , where $q^$ is determined by the local medium quantities as provided by hydrodynamical calculations. We find that this $K$ factor is larger at RHIC than at the LHC, as obtained already in previous analyses, but, surprisingly, it is almost independent of the centrality of the collision. Taken at face value, the $K$ factor would not depend on the local properties of the medium as energy density or temperature, but on global collision quantities such as the center of mass energy. This is a very intriguing, unexpected possibility for which we cannot yet provide a clear interpretation. We also comment on the limitations of the formalism that may affect this conclusion.
Comments:
26 pages, 7 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
1606.04837 [pdf]
EPJC(2016)·105 citations
10
[Submitted on 13 Jun 2016] (cross-list from astro-ph.HE)
The internal composition of proto-neutron stars under strong magnetic fields
B. Franzon · V. Dexheimer · S. Schramm
In this work, we study the effects of magnetic fields and rotation on the structure and composition of proto-neutron stars (PNS's). A hadronic chiral SU(3) model is applied to cold neutron stars (NS) and proto-neutron stars with trapped neutrinos and at fixed entropy per baryon. We obtain general relativistic solutions for neutron and proto-neutron stars endowed with a poloidal magnetic field by solving Einstein-Maxwell field equations in a self-consistent way. As the neutrino chemical potential decreases in value over time, this alters the chemical equilibrium and the composition inside the star, leading to a change in the structure and in the particle population of these objects. We find that the magnetic field deforms the star and significantly alters the number of trapped neutrinos in the stellar interior, together with strangeness content and temperature in each evolution stage.
Comments:
Accepted for publication in PRD
Subjects:
High Energy Astrophysical Phenomena (astro-ph.HE); Nuclear Theory (nucl-th)
arXiv:
1606.04843 [pdf]
PRD(2016)·33 citations
11
[Submitted on 8 Jun 2016] (cross-list from astro-ph.HE)
Vortex pinning and dynamics in the neutron star crust
Gabriel Wlazłowski · Kazuyuki Sekizawa · Piotr Magierski · Aurel Bulgac · Michael McNeil Forbes
The nature of the interaction between superfluid vortices and the neutron star crust, conjectured by Anderson and Itoh in 1975 to be at the heart vortex creep and the cause of glitches, has been a long-standing question in astrophysics. Using a qualitatively new approach, we follow the dynamics as superfluid vortices move in response to the presence of "nuclei" (nuclear defects in the crust). The resulting motion is perpendicular to the force, similar to the motion of a spinning top when pushed. We show that nuclei repel vortices in the neutron star crust, and characterize the force as a function of the vortex-nucleus separation.
Comments:
supplemental materials included
Subjects:
High Energy Astrophysical Phenomena (astro-ph.HE); Solar and Stellar Astrophysics (astro-ph.SR); Superconductivity (cond-mat.supr-con); Nuclear Theory (nucl-th)
arXiv:
1606.04847 [pdf]
PRL(2016)·79 citations

Affiliations

first authorsco-authorsvia INSPIRE

An effective-field-theory analysis of Efimov physics in heteronuclear mixtures of ultracold atomic gases

An electroweak basis for neutrinoless double β decay

Kˉ -induced formation of the f2​(1270) and f2′​(1525) resonances on proton targets

Instantaneous Bethe-Salpeter View of Goldstone-Type Pseudoscalar Mesons

Energy versus centrality dependence of the jet quenching parameter q^​ at RHIC and LHC: a new puzzle?

The internal composition of proto-neutron stars under strong magnetic fields

Vortex pinning and dynamics in the neutron star crust

Affiliations

An electroweak basis for neutrinoless double $β$ decay

$K ˉ$ -induced formation of the $f_{2} (1270)$ and $f_{2}^{^{'}} (1525)$ resonances on proton targets

Energy versus centrality dependence of the jet quenching parameter $q^$ at RHIC and LHC: a new puzzle?