Nuclear Theory·nucl-th

Thursday·March 4, 2021

14 papers—4 primary·10 cross-listed

05
Higher-spin particles at high-energy colliders
Juan Carlos Criado🇬🇧 · Abdelhak Djouadi🇪🇪 · Niko Koivunen🇪🇪 · Martti Raidal🇪🇪 · Hardi Veermäe🇪🇪
Using an effective field theory approach for higher-spin fields, we derive the interactions of colour singlet and electrically neutral particles with a spin higher than unity, concentrating on the spin-3/2, spin-2, spin-5/2 and spin-3 cases. We compute the decay rates and production cross sections in the main channels for spin-3/2 and spin-2 states at both electron-positron and hadron colliders, and identify the most promising novel experimental signatures for discovering such particles at the LHC. The discussion is qualitatively extended to the spin-5/2 and spin-3 cases. Higher-spin particles exhibit a rich phenomenology and have signatures that often resemble the ones of supersymmetric and extra-dimensional theories. To enable further studies of higher-spin particles at collider and beyond, we collect the relevant Feynman rules and other technical details.
↳ hep-phhep-exhep-thnucl-thJHEP(2021)·13 citations
06
Tests of collectivity in $^{98}$ Zr by absolute transition rates
V. Karayonchev🇩🇪 · J. Jolie🇩🇪 · A. Blazhev🇩🇪 · A. Dewald🇩🇪 · A. Esmaylzadeh🇩🇪 · C. Fransen🇩🇪 · G. Häfner🇩🇪 · L. Knafla🇩🇪 · J. Litzinger🇩🇪 · C. Müller-Gatermann🇩🇪 · J.-M. Régis🇩🇪 · K. Schomacker🇩🇪 and 4 other authors
Lifetimes of low-spin excited states in $^{98}$ Zr were measured using the recoil-distance Doppler-shift technique and the Doppler-shift attenuation method. The nucleus of interest was populated in a $^{96}$ Zr( $^{18}$ O, $^{16}$ O) $^{98}$ Zr two-neutron transfer reaction at the Cologne FN Tandem accelerator. Lifetimes of six low-spin excited states, of which four are unknown, were measured. The deduced $B (E 2)$ values were compared with Monte Carlo shell model and interacting boson model with configuration mixing calculations. Both approaches reproduce well most of the data but leave challenging questions regarding the structure of some low lying states.
↳ nucl-exnucl-thPRC(2020)·30 citations
07
Mirror Neutron Stars
Maurício Hippert🇺🇸 · Jack Setford🇨🇦 · Hung Tan🇺🇸 · David Curtin🇨🇦 · Jacquelyn Noronha-Hostler🇺🇸 · Nicolas Yunes🇺🇸
The fundamental nature of dark matter is entirely unknown. A compelling candidate is Twin Higgs mirror matter, invisible hidden-sector cousins of the Standard Model particles and forces. This predicts mirror neutron stars made entirely of mirror nuclear matter. We find their structure using realistic equations of state, robustly modified based on first-principle quantum chromodynamic calculations, for the first time. This allows us to predict their gravitational wave signals, demonstrating an impressive discovery potential and ability to probe dark sectors connected to the hierarchy problem.
↳ astro-ph.HEgr-qchep-phnucl-thPRD(2022)·78 citations
08
On the scalar $π K$ form factor beyond the elastic region
Leon von Detten🇩🇪 · Frederic Noël🇩🇪 · Christoph Hanhart🇩🇪 · Martin Hoferichter🇨🇭 · Bastian Kubis🇩🇪
Pion-kaon ( $π K$ ) pairs occur frequently as final states in heavy-particle decays. A consistent treatment of $π K$ scattering and production amplitudes over a wide energy range is therefore mandatory for multiple applications: in Standard Model tests; to describe crossed channels in the quest for exotic hadronic states; and for an improved spectroscopy of excited kaon resonances. In the elastic region, the phase shifts of $π K$ scattering in a given partial wave are related to the phases of the respective $π K$ form factors by Watson's theorem. Going beyond that, we here construct a representation of the scalar $π K$ form factor that includes inelastic effects via resonance exchange, while fulfilling all constraints from $π K$ scattering and maintaining the correct analytic structure. As a first application, we consider the decay $τ \to K_{S} π ν_{τ}$ , in particular, we study to which extent the $S$ -wave $K_{0}^{*} (1430)$ and the $P$ -wave $K^{*} (1410)$ resonances can be differentiated and provide an improved estimate of the $C P$ asymmetry produced by a tensor operator. Finally, we extract the pole parameters of the $K_{0}^{*} (1430)$ and $K_{0}^{*} (1950)$ resonances via Padé approximants, $s_{K_{0}^{*} (1430)} = [1408 (48) - i 180 (48)]$ MeV and $s_{K_{0}^{*} (1950)} = [1863 (12) - i 136 (20)]$ MeV, as well as the pole residues. A generalization of the method also allows us to formally define a branching fraction for $τ \to K_{0}^{*} (1430) ν_{τ}$ in terms of the corresponding residue, leading to the upper limit $BR (τ \to K_{0}^{*} (1430) ν_{τ}) < 1.6 \times 1 0^{- 4}$ .
↳ hep-phhep-exnucl-thEPJC(2021)·30 citations
09
Actinide crystallization and fission reactions in cooling white dwarf stars
C. J. Horowitz🇺🇸 · M. E. Caplan🇺🇸
The first solids that form as a cooling white dwarf (WD) starts to crystallize are expected to be greatly enriched in actinides. This is because the melting points of WD matter scale as $Z^{5/3}$ and actinides have the largest charge $Z$ . We estimate that the solids may be so enriched in actinides that they could support a fission chain reaction. This reaction could ignite carbon burning and lead to the explosion of an isolated WD in a thermonuclear supernova (SN Ia). Our mechanism could potentially explain SN Ia with sub-Chandrasekhar ejecta masses and short delay times.
↳ astro-ph.SRastro-ph.HEnucl-thPRL(2021)·10 citations
10
Towards the three-dimensional parton structure of the pion: Integrating transverse momentum data into global QCD analysis
N. Y. Cao🇺🇸 · P. C. Barry🇺🇸 · N. Sato🇺🇸 · W. Melnitchouk🇺🇸
We perform a new Monte Carlo QCD analysis of pion parton distribution functions, including, for the first time, transverse momentum dependent pion-nucleus Drell-Yan cross sections together with $p_{T}$ -integrated Drell-Yan and leading neutron electroproduction data from HERA. We assess the sensitivity of the Monte Carlo fits to kinematic cuts, factorization scale, and parametrization choice, and we discuss the impact of the various datasets on the pion's quark and gluon distributions. This study provides the necessary step towards the simultaneous analysis of collinear and transverse momentum dependent pion distributions and the determination of the pion's three-dimensional structure.
↳ hep-phhep-exhep-latnucl-thPRD(2021)·42 citations
11
Progenitor Dependence of Hadron-quark Phase Transition in Failing Core-collapse Supernovae
Shuai Zha🇸🇪 · Evan P. O'Connor🇸🇪 · André da Silva Schneider🇸🇪
We study the consequences of a hadron-quark phase transition (PT) in failing core-collapse supernovae (CCSNe) which give birth to stellar-mass black holes (BH). We perform a suite of neutrino-transport general-relativistic hydrodynamic simulations in spherical symmetry with 21 progenitor models and a hybrid equation of state (EoS) including hadrons and quarks. We find that the effect of the PT on the CCSN postbounce dynamics is a function of the bounce compactness parameter $ξ_{2.2}$ . For $ξ_{2.2} ≳ 0.24$ , the PT leads to a second dynamical collapse of the protocompact star (PCS). While BH formation starts immediately after this second collapse for models with $ξ_{2.2} ≳ 0.51$ , the PCS experiences a second bounce and oscillations for models with $0.24 ≲ ξ_{2.2} ≲ 0.51$ . These models emit potent oscillatory neutrino signals with a period of $\sim$ ms for tens of ms after the second bounce, which can be a strong indicator of the PT in failing CCSNe if detected in the future. However, no shock revival occurs and BH formation inevitably takes place in our spherically-symmetric simulations. Furthermore, via a diagram of mass-specific entropy evolution of the PCS, the progenitor dependence can be understood through the appearance of third-family of compact stars emerging at large entropy induced by the PT.
↳ astro-ph.HEnucl-thApJ(2021)·35 citations
12
Pseudo spin doublet bands and Gallagher Moszkowski doublet bands in $^{100}$ Y
E. H. Wang🇺🇸 · J. H. Hamilton🇺🇸 · A. V. Ramayya🇺🇸 · C. J. Zachary🇺🇸 · A. Lemasson🇫🇷 · A. Navin🇫🇷 · M. Rejmund🇫🇷 · S. Bhattacharyya🇮🇳 · Q. B. Chen🇨🇳 · S. Q. Zhang🇨🇳 · J. M. Eldridge🇺🇸 · J. K. Hwang🇺🇸 and 12 other authors
New transitions in neutron rich $^{100}$ Y have been identified in a $^{9}$ Be+ $^{238}$ U experiment with mass- and Z- gates to provide full fragment identification. These transitions and high spin levels of $^{100}$ Y have been investigated by analyzing the high statistics $γ$ - $γ$ - $γ$ and $γ$ - $γ$ - $γ$ - $γ$ coincidence data from the spontaneous fission of $^{252}$ Cf at the Gammasphere detector array. Two new bands, 14 new levels and 23 new transitions have been identified. The $K^{π} = 4^{+}$ new band decaying to an 1s isomeric state is assigned to be the high- $K$ Gallagher-Moszkowski (GM) partner of the known $K^{π} = 1^{+}$ band, with the $π 5/2 [522] \otimes ν 3/2 [411]$ configuration. This 4 $^{+}$ band is also proposed to be the pseudo spin partner of the new $K^{π} = 5^{+}$ band with a 5 $^{+}$ $π 5/2 [422] \otimes ν 5/2 [413]$ configuration, to form a $π 5/2 [422] \otimes ν [312$ $5/2, 3/2]$ neutron pseudospin doublet. Constrained triaxial covariant density functional theory and quantal particle rotor model calculations have been applied to interpret the band structure and available electromagnetic transition probabilities and are found in good agreement with experimental values.
↳ nucl-exnucl-thPRC(2021)·7 citations
13
Spin polarization dynamics in the Bjorken-expanding resistive MHD background
Rajeev Singh🇵🇱 · Masoud Shokri🇮🇷 · Radoslaw Ryblewski🇵🇱
Evolution of spin polarization in the presence of external electric field is studied for collision energies $s_{NN} = 27 GeV$ and $s_{NN} = 200 GeV$ . The numerical analysis is done in the perfect-fluid Bjorken-expanding resistive magnetohydrodynamic background and novel results are reported. In particular, we show that the electric field plays a significant role in the competition between expansion and dissipation.
↳ hep-phhep-thnucl-thPRD(2021)·29 citations
14
Real-time lattice gauge theory actions: unitarity, convergence, and path integral contour deformations
Gurtej Kanwar🇺🇸 · Michael L. Wagman🇺🇸
The Wilson action for Euclidean lattice gauge theory defines a positive-definite transfer matrix that corresponds to a unitary lattice gauge theory time-evolution operator if analytically continued to real time. Hoshina, Fujii, and Kikukawa (HFK) recently pointed out that applying the Wilson action discretization to continuum real-time gauge theory does not lead to this, or any other, unitary theory and proposed an alternate real-time lattice gauge theory action that does result in a unitary real-time transfer matrix. The character expansion defining the HFK action is divergent, and in this work we apply a path integral contour deformation to obtain a convergent representation for U(1) HFK path integrals suitable for numerical Monte Carlo calculations. We also introduce a class of real-time lattice gauge theory actions based on analytic continuation of the Euclidean heat-kernel action. Similar divergent sums are involved in defining these actions, but for one action in this class this divergence takes a particularly simple form, allowing construction of a path integral contour deformation that provides absolutely convergent representations for U(1) and SU(N) real-time lattice gauge theory path integrals. We perform proof-of-principle Monte Carlo calculations of real-time U(1) and SU(3) lattice gauge theory and verify that exact results for unitary time evolution of static quark-antiquark pairs in (1 + 1)D are reproduced.
↳ hep-lathep-phhep-thnucl-th+1PRD(2021)·26 citations

Affiliations

first authorsco-authorsvia INSPIRE