Nuclear Theory·nucl-th

Wednesday·November 18, 2020

10 papers—3 primary·7 cross-listed

04
[Submitted on 16 Nov 2020] (cross-list from hep-ex)
Observation of a near-threshold structure in the $K^{+}$ recoil-mass spectra in $e^{+} e^{-} \to K^{+} (D_{s}^{-} D^{* 0} + D_{s}^{*-} D^{0})$
BESIII Collaboration: M. Ablikim🇨🇳 · M. N. Achasov🇷🇺 · P. Adlarson🇸🇪 · S. Ahmed🇩🇪 · M. Albrecht🇩🇪 · R. Aliberti🇩🇪 · A. Amoroso🇮🇹 · Q. An🇨🇳 · Anita🇮🇳 · X. H. Bai🇨🇳 · Y. Bai🇨🇳 · O. Bakina🇷🇺 and 493 other authors
We report a study of the processes of $e^{+} e^{-} \to K^{+} (D_{s}^{-} D^{* 0} + D_{s}^{*-} D^{0})$ based on $e^{+} e^{-}$ annihilation samples collected with the BESIII detector operating at BEPCII at five center-of-mass energies ranging from 4.628 to 4.698 GeV with a total integrated luminosity of 3.7 fb $^{- 1}$ . An excess over the known contributions of the conventional charmed mesons is observed near the $D_{s}^{-} D^{* 0}$ and $D_{s}^{*-} D^{0}$ mass thresholds in the $K^{+}$ recoil-mass spectrum for events collected at $s = 4.681$ GeV. The structure matches a mass-dependent-width Breit-Wigner line shape, whose pole mass and width are determined as $(3982. 5_{- 2.6}^{+ 1.8} \pm 2.1)$ MeV/ $c^{2}$ and $(12. 8_{- 4.4}^{+ 5.3} \pm 3.0)$ MeV, respectively. The first uncertainties are statistical and the second are systematic. The significance of the resonance hypothesis is estimated to be 5.3 $σ$ over the contributions only from the conventional charmed mesons. This is the first candidate of the charged hidden-charm tetraquark with strangeness, decaying into $D_{s}^{-} D^{* 0}$ and $D_{s}^{*-} D^{0}$ . However, the properties of the excess need further exploration with more statistics.
Comments:
17 pages; Version published in Phys. Rev. Lett
Subjects:
High Energy Physics — Experiment (hep-ex); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2011.07855 [pdf]
PRL(2021)·290 citations
05
[Submitted on 16 Nov 2020] (cross-list from hep-ph)
Transasymptotics and hydrodynamization of the Fokker-Planck equation for gluons
A. Behtash🇺🇸 · S. Kamata🇵🇱 · M. Martinez🇺🇸 · T. Schaefer🇺🇸 · V. Skokov🇺🇸
We investigate the non-linear transport processes and hydrodynamization of a system of gluons undergoing longitudinal boost-invariant expansion. The dynamics is described within the framework of the Boltzmann equation in the small-angle approximation. The kinetic equations for a suitable set of moments of the one-particle distribution function are derived. By investigating the stability and asymptotic resurgent properties of this dynamical system, we demonstrate, that its solutions exhibit a rather different behavior for large (UV) and small (IR) effective Knudsen numbers. Close to the forward attractor in the IR regime the constitutive relations of each moment can be written as a multiparameter transseries. This resummation scheme allows us to extend the definition of a transport coefficient to the non-equilibrium regime naturally. Each transport coefficient is renormalized by the non-perturbative contributions of the non-hydrodynamic modes. The Knudsen number dependence of the transport coefficient is governed by the corresponding renormalization group flow equation. An interesting feature of the Yang-Mills plasma in this regime is that it exhibits transient non-Newtonian behavior while hydrodynamizing. In the UV regime the solution for the moments can be written as a power-law asymptotic series with a finite radius of convergence. We show that radius of convergence of the UV perturbative expansion grows linearly as a function of the shear viscosity to entropy density ratio. Finally, we compare the universal properties in the pullback and forward attracting regions to other kinetic models including the relaxation time approximation and the effective kinetic Arnold-Moore-Yaffe (AMY) theory.
Comments:
v2: 23 pages + appendices, 7 figures, updated references. Added new subsection IVB which is related with transasymptotic matching and RG flow equations of 1st. and 2nd. order transport coefficients for the most general case. Accepted for publication in PRD
Subjects:
High Energy Physics — Phenomenology (hep-ph); Statistical Mechanics (cond-mat.stat-mech); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th); Fluid Dynamics (physics.flu-dyn)
arXiv:
2011.08235 [pdf]
PRD(2021)·26 citations
06
[Submitted on 17 Nov 2020] (cross-list from hep-th)
Quasi-universal relations for generalized Skyrme stars
Christoph Adam🇪🇸 · Alberto García Martín-Caro🇪🇸 · Miguel Huidobro🇪🇸 · Ricardo Vázquez🇪🇸 · Andrzej Wereszczynski🇵🇱
First proposed in 2013 by Yagi and Yunes, the quasi-universal \emph{I-Love-Q relations} consist of a set of relations between the moment of inertia, the spin-induced quadrupole moment and the electric quadrupolar tidal deformability of neutron stars which are independent of the Equation of State (EoS) within an accuracy of $\sim 1%$ . In this work, we show that these relations hold for different Skyrme-based nuclear matter EoS and also for the star-like solutions of different Einstein-BPS-Skyrme-models, some of which do not even present a barotropic equation of state. Further, other quasi-universal relations are analyzed, and together with recent GW observations, we use them to select the generalized Skyrme model that better reproduces observations. Our results reaffirm both the universality of the \emph{I-Love-Q} relations and the suitability of generalized Skyrme models to describe nuclear matter inside neutron stars.
Comments:
23 pages, 11 figures
Subjects:
High Energy Physics — Theory (hep-th); General Relativity and Quantum Cosmology (gr-qc); Nuclear Theory (nucl-th)
arXiv:
2011.08573 [pdf]
PRD(2021)·15 citations
07
[Submitted on 17 Nov 2020] (cross-list from hep-ph)
Transverse-momentum-dependent parton distribution functions up to twist 4 for spin-1 hadrons
S. Kumano🇯🇵 · Qin-Tao Song🇨🇳
We show possible transverse-momentum-dependent parton distribution functions (TMDs) for spin-1 hadrons including twist-3 and 4 functions in addition to the leading twist-2 ones by investigating all the possible decomposition of a quark correlation function in the Lorentz-invariant way. The Hermiticity and parity invariance are imposed in the decomposition; however, the time-reversal invariance is not used due to an active role of gauge links in the TMDs. Therefore, there exist time-reversal-odd functions in addition to the time-reversal even ones in the TMDs. We list all the functions up to twist-4 level because there were missing terms associated with the lightcone vector $n$ in previous works on the twist-2 part and there was no correlation-function study in the twist-3 and 4 parts for spin-1 hadrons. We show that 40 TMDs exist in the tensor-polarized spin-1 hadron in twists 2, 3, and 4. Some expressions of twist-2 structure functions are modified from previous derivations due to the new terms with $n$ , and we find 30 new structure functions in twists 3 and 4 in this work. Since time-reversal-odd terms of the collinear correlation function should vanish after integrals over the partonic transverse momentum, we obtain new sum rules for the time-reversal-odd structure functions, $\int d^{2} k_{T} h_{L T} = \int d^{2} k_{T} h_{LL} = \int d^{2} k_{T} h_{3 LL} = 0$ . In addition, we indicate that new transverse-momentum-dependent fragmentation functions exist in tensor-polarized spin-1 hadrons. The TMDs are rare observables to find explicit color degrees of freedom in terms of color flow, which cannot be usually measured because the color is confined in hadrons.
Comments:
18 pages, 12 eps figures and tables, typos in abstract and summary are corrected
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); High Energy Physics — Lattice (hep-lat); Nuclear Theory (nucl-th)
arXiv:
2011.08583 [pdf]
PRD(2021)·39 citations
08
[Submitted on 16 Nov 2020] (cross-list from nucl-ex)
The origin of the elements and other implications of gravitational wave detection for nuclear physics
David Lunney🇫🇷
The neutron-star collision revealed by the event GW170817 gave us a first glimpse of a possible birthplace of most of our heavy elements. The multi-messenger nature of this historical event combined gravitational waves, a gamma-ray burst and optical astronomy of a ``kilonova'', bringing the first observations of rapid neutron capture (r process) nucleosynthesis after 60 years of speculation. Modeling the r process requires a prodigious amount of nuclear-physics ingredients: practically all the quantum state and interaction properties of virtually all neutron-rich nuclides, many of which may never be produced in the laboratory! Another essential contribution of nuclear physics to neutron stars (and their eventual coalescence) is the equation of state (EoS) that defines their structure and composition. The EoS, combined with the knowledge of nuclear binding energies, determines the elemental profile of the outer crust of a neutron star and the relationship between its radius and mass. In addition, the EoS determines the form of the gravitational wave signal. This article combines a tutorial presentation and bibliography with recent results that link nuclear mass spectrometry to gravitational waves via neutron stars.
Comments:
Invited tutorial/review paper for a Special Issue of 4Open-Sciences (EDP) on "Gravitational waves and the advent of multi-messenger astronomy," following a minisymposium bearing the same title, held during the 2019 National Conference of the SFP (Société Française de Physique) in Nantes, France (14 pages, 3 figures)
Subjects:
Nuclear Experiment (nucl-ex); High Energy Astrophysical Phenomena (astro-ph.HE); Nuclear Theory (nucl-th)
arXiv:
2011.08645 [pdf]
4open(2020)·2 citations
09
[Submitted on 17 Nov 2020] (cross-list from hep-ph)
$Z_{cs} (3985)^{-}$ as the $U$ -spin partner of $Z_{c} (3900)^{-}$ and implication of other states in the $SU(3)_{F}$ symmetry and heavy quark symmetry
Lu Meng🇨🇳 · Bo Wang🇨🇳 · Shi-Lin Zhu🇨🇳
Recently, for the first time, the BESIII Collaboration reported the strange hidden charm tetraquark states $Z_{cs} (3985)^{-}$ in the $K^{+}$ recoil-mass spectrum near the $D_{s}^{-} D^{* 0} / D_{s}^{*-} D^{0}$ mass thresholds in the processes of $e^{+} e^{-} \to K^{+} (D_{s}^{-} D^{* 0} + D_{s}^{*-} D^{0})$ at $s = 4.681$ GeV. The significance was estimated to be 5.3 $σ$ . We show that the newly observed $Z_{cs} (3985)^{-}$ state is the $U$ -spin partner of $Z_{c} (3900)^{-}$ as a resonance within coupled-channel calculation in the $SU(3)_{F}$ symmetry and heavy quark spin symmetry (HQSS). In the $SU(3)_{F}$ symmetry, we introduce the $G_{U / V}$ parity to construct the flavor wave functions of the $Z_{cs}$ states. In a unified framework, we consider the $J / ψ π (K)$ , $D ˉ_{(s)} D^{*} / D ˉ_{(s)}^{*} D$ coupled-channel effect with the contact interaction. With the masses and widths of $Z_{c} (3900)$ and $Z_{c} (4020)$ , we determine all the unknown coupling constants. We obtain mass and width of $Z_{cs} (3985)$ in good agreement with the experimental results, which strongly supports the $Z_{cs}$ states as the $U / V$ -spin partner states of the charged $Z_{c} (3900)$ . We also calculate the ratio of the partial decay widths of $Z_{cs} (3985)$ , which implies that the $D ˉ_{s} D^{*} / D ˉ_{s}^{*} D$ decay modes are dominant. We also predict the $Z_{cs}^{'}$ states with a mass around $4130$ MeV and width around $30$ MeV, which are the $U / V$ -spin partner states of the charged $Z_{c} (4020)$ and HQSS partner states of the $Z_{cs} (3985)$ . In the hidden bottom sector, we predict the strange tetraquark states $Z_{b s}$ and $Z_{b s}^{'}$ with a mass around 10700 MeV and 10750 MeV, which are the $U / V$ -spin partner states of $Z_{b} (10610)^{\pm}$ and $Z_{b} (10650)^{\pm}$ , respectively.
Comments:
6 pages, 2 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); High Energy Physics — Lattice (hep-lat); Nuclear Theory (nucl-th)
arXiv:
2011.08656 [pdf]
PRD(2020)·81 citations
10
[Submitted on 17 Nov 2020] (cross-list from hep-ph)
Strange molecular partners of the $Z_{c} (3900)$ and $Z_{c} (4020)$
Zhi Yang🇨🇳 · Xu Cao🇨🇳 · Feng-Kun Guo🇨🇳 · Juan Nieves🇪🇸 · Manuel Pavon Valderrama🇨🇳
Quantum Chromodynamics presents a series of exact and approximate symmetries which can be exploited to predict new hadrons from previously known ones. The $Z_{c} (3900)$ and $Z_{c} (4020)$ resonances, which have been theorized to be isovector $D^{*} D ˉ$ and $D^{*} D ˉ^{*}$ molecules [ $I^{G} (J^{P C}) = 1^{-} (1^{+-})$ ], are no exception. Here we argue that from SU(3)-flavor symmetry, we should expect the existence of strange partners of the $Z_{c}$ 's with hadronic molecular configurations $D^{*} D ˉ_{s}$ - $D D ˉ_{s}^{*}$ and $D^{*} D ˉ_{s}^{*}$ (or, equivalently, quark content $c c ˉ s q ˉ$ , with $q = u, d$ ). The quantum numbers of these $Z_{cs}$ and $Z_{cs}^{*}$ resonances would be $I (J^{P})$ = $\frac{1}{2} (1^{+})$ . The predicted masses of these partners depend on the details of the theoretical scheme used, but they should be around the $D^{*} D ˉ_{s}$ - $D D ˉ_{s}^{*}$ and $D^{*} D ˉ_{s}^{*}$ thresholds, respectively. Moreover, any of these states could be either a virtual pole or a resonance. We show that, together with a possible triangle singularity contribution, such a picture nicely agrees with the very recent BESIII data of the $e^{+} e^{-} \to K^{+} (D_{s}^{-} D^{* 0} + D_{s}^{*-} D^{0})$ .
Comments:
8 pages, 5 figures; note added commenting on the Zcs structures reported recently by LHCb
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); High Energy Physics — Lattice (hep-lat); Nuclear Theory (nucl-th)
arXiv:
2011.08725 [pdf]
PRD(2021)·101 citations

Affiliations

first authorsco-authorsvia INSPIRE

Observation of a near-threshold structure in the K+ recoil-mass spectra in e+e−→K+(Ds−​D∗0+Ds∗−​D0)

Transasymptotics and hydrodynamization of the Fokker-Planck equation for gluons

Quasi-universal relations for generalized Skyrme stars

Transverse-momentum-dependent parton distribution functions up to twist 4 for spin-1 hadrons

The origin of the elements and other implications of gravitational wave detection for nuclear physics

Zcs​(3985)− as the U-spin partner of Zc​(3900)− and implication of other states in the SU(3)F​ symmetry and heavy quark symmetry

Strange molecular partners of the Zc​(3900) and Zc​(4020)

Affiliations

Observation of a near-threshold structure in the $K^{+}$ recoil-mass spectra in $e^{+} e^{-} \to K^{+} (D_{s}^{-} D^{* 0} + D_{s}^{*-} D^{0})$

$Z_{cs} (3985)^{-}$ as the $U$ -spin partner of $Z_{c} (3900)^{-}$ and implication of other states in the $SU(3)_{F}$ symmetry and heavy quark symmetry

Strange molecular partners of the $Z_{c} (3900)$ and $Z_{c} (4020)$