Nuclear Theory·nucl-th

Wednesday·March 17, 2021

4 papers—1 primary·3 cross-listed

02
Anti- $k_{T}$ jet function at next-to-next-to-leading order
Hao-yu Liu🇨🇳 · Xiaohui Liu🇨🇳 · Sven-Olaf Moch🇩🇪
Jets constructed via clustering algorithms (e.g., anti- $k_{T}$ , soft-drop) have been proposed for many precision measurements, such as the strong coupling $α_{s}$ and the nucleon intrinsic dynamics. However, the theoretical accuracy is affected by missing QCD corrections at higher orders for the jet functions in the associated factorization theorems. Their calculation is complicated by the jet clustering procedure. In this work, we propose a method to evaluate jet functions at higher orders in QCD. The calculation involves the phase space sector decomposition with suitable soft subtractions. As a concrete example, we present the quark-jet function using the anti- $k_{T}$ algorithm with E-scheme recombination at next-to-next-to-leading order.
↳ hep-phnucl-thPRD(2021)·15 citations
03
First observation of a nuclear $s$ -state of $Ξ$ hypernucleus, $_{Ξ}^{15} C$
M. Yoshimoto🇯🇵 · J. K. Ahn🇰🇷 · B. Bassalleck🇺🇸 · H. Ekawa🇯🇵 · Y. Endo🇯🇵 · M. Fujita🇯🇵 · Y. Han🇨🇳 · T. Hashimoto🇯🇵 · S. H. Hayakawa🇯🇵 · K. Hicks🇺🇸 · K. Hoshino🇯🇵 · S. Hoshino🇯🇵 and 37 other authors
Bound-systems of $Ξ^{-}$ -- $_{14} N$ are studied via $Ξ^{-}$ capture at rest followed by emission of a twin single- $Λ$ hypernucleus in the emulsion detectors. Two events forming extremely deep $Ξ^{-}$ bound states were obtained by analysis of a hybrid method in the E07 experiment at J-PARC and reanalysis of the E373 experiment at KEK-PS. The decay mode of one event was assigned as $Ξ^{-} +_{14} N \to_{Λ}^{5} He$ + $_{Λ}^{5} He$ + $_{4} He$ +n. Since there are no excited states for daughter particles, the binding energy of the $Ξ^{-}$ hyperon, $B_{Ξ^{-}}$ , in $_{14} N$ nucleus was uniquely determined to be 6.27 $\pm$ 0.27 MeV. Another $Ξ^{-}$ -- $_{14} N$ system via the decay $_{Λ}^{9} Be$ + $_{Λ}^{5} He$ + n brings a $B_{Ξ^{-}}$ value, 8.00 $\pm$ 0.77 MeV or 4.96 $\pm$ 0.77 MeV, where the two possible values of $B_{Ξ^{-}}$ correspond to the ground and the excited states of the daughter $_{Λ}^{9} Be$ nucleus, respectively. Because the $B_{Ξ^{-}}$ values are larger than those of the previously reported events (KISO and IBUKI), which are both interpreted as the nuclear $1 p$ state of the $Ξ^{-}$ -- $_{14} N$ system, these new events give the first indication of the nuclear $1 s$ state of the $Ξ$ hypernucleus, $_{Ξ}^{15} C$ .
↳ nucl-exnucl-thphysics.ins-detPTEP(2021)·57 citations
04
Spin polarization induced by the hydrodynamic gradients
Shuai Y. F. Liu🇨🇳 · Yi Yin🇨🇳
We systematically analyze the effects of the derivatives of the hydrodynamic fields on axial Wigner function that describes the spin polarization vector in phase space. We have included all possible first-order derivative contributions that are allowed by symmetry and compute the associated transport functions at one-loop using the linear response theory. In addition to reproducing known effects due to the temperature gradient and vorticity, we have identified a number of potentially significant contributions that are overlooked previously. In particular, we find that the shear strength, the symmetric and traceless part of the flow gradient, will induce a quadrupole for spin polarization in the phase space. We refer to this novel effect as the shear-induced polarization (SIP). Our results, together with hydrodynamic gradients obtained from hydrodynamic simulations, can be employed as a basis for the interpretation of the $Λ$ (anti- $Λ$ ) spin polarization measurement in heavy-ion collisions.
↳ hep-phnucl-thJHEP(2021)·163 citations

Affiliations

first authorsco-authorsvia INSPIRE

Anti-kT​ jet function at next-to-next-to-leading order

First observation of a nuclear s-state of Ξ hypernucleus, Ξ15​C

Spin polarization induced by the hydrodynamic gradients

Affiliations

Anti- $k_{T}$ jet function at next-to-next-to-leading order

First observation of a nuclear $s$ -state of $Ξ$ hypernucleus, $_{Ξ}^{15} C$