Nuclear Theory·nucl-th

Tuesday·March 10, 2020

9 papers—5 primary·4 cross-listed

06
[Submitted on 7 Mar 2020] (cross-list from nucl-ex)
Polarization and Vorticity in the Quark Gluon Plasma
Francesco Becattini🇮🇹 · Michael Lisa🇺🇸
The quark-gluon plasma produced by collisions between ultra-relativistic heavy nuclei is well described in the language of hydrodynamics. Non-central collisions are characterized by very large angular momentum, which in a fluid system manifests as flow vorticity. This rotational structure can lead to a spin polarization of the hadrons that eventually emerge from the plasma, providing experimental access to flow substructure at unprecedented detail. Recently, first observations of $Λ$ hyperon polarization along the direction of collisional angular momentum have been reported. These measurements are in broad agreement with hydrodynamic and transport-based calculations and reveal that the QGP is the most vortical fluid ever observed. However, there remain important tensions between theory and observation which might be fundamental in nature. In the relatively mature field of heavy ion physics, the discovery of global hyperon polarization and three-dimensional simulations of the collision have opened an entirely new direction of research. We discuss the current status of this rapidly developing area and directions for future research.
Comments:
30 pages, 6 figures; Invited review article for Annual Review of Nuclear and Particle Science; Comments to the authors are welcome! When citing this paper, please use the following: Becattini F, Lisa M. 2020. Title. Annu. Rev. Nucl. Part. Sci: Submitted. DOI: 10.1146/annurev-nucl-021920-095245
Subjects:
Nuclear Experiment (nucl-ex); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2003.03640 [pdf]
Ann.Rev.Nucl.Part.Sci.(2020)·292 citations
07
[Submitted on 8 Mar 2020] (cross-list from hep-ph)
Semi-Inclusive Jet Functions and Jet Substructure in $J_{E_{T}}^{(I)}$ and $J_{E_{T}}^{(I I)}$ Algorithms
Lei Wang🇨🇳 · Zhong-Bo Kang🇺🇸 · Hongxi Xing🇨🇳 · Ben-Wei Zhang🇨🇳
Within the framework of Soft Collinear Effective Theory, we present calculations of semi-inclusive jet functions and fragmenting jet functions at next-to-leading order (NLO) for both quark- and gluon-initiated jets, for jet algorithms of $J_{E_{T}}^{(I)}$ and $J_{E_{T}}^{(I I)}$ where one maximizes a suitable jet function. We demonstrate the consistency of the obtained results with the standard perturbative QCD calculations for $J_{E_{T}}^{(I)}$ algorithm, while the results for fragmenting jet functions with the $J_{E_{T}}^{(I I)}$ algorithm are new. The renormalization group (RG) equation for both semi-inclusive jet functions and fragmenting jet functions are derived and shown to follow the time-like DGLAP evolution equations, independent of specific jet algorithms. The RG equation can be used to resum single logarithms of the jet size parameter $β$ for highly collimated jets in these algorithms where $β ≫ 1$ .
Comments:
16 pages, 2 figures, typos corrected, some analytical results updated
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2003.03796 [pdf]
PRD(2021)·3 citations
08
[Submitted on 6 Mar 2020] (cross-list from hep-ph)
$Y (4260)$ as four-quark state
Anna Zuzana Dubnickova🇸🇰 · Stanislav Dubnicka🇸🇰 · Aidos Issadykov🇷🇺 · Mikhail Alekseevich Ivanov🇷🇺 · Andrej Liptaj🇸🇰
We treat the $Y (4260)$ resonance as a four-quark state in the framework of the covariant confining quark model. We study two choices of the interpolating current, either the molecular-type current which effectively corresponds to the product of $D$ and $D ˉ_{1}$ quark currents or tetraquark one. In both cases we calculate the widths of decays $Y (4260) \to Z_{c} (3900) + π$ and $Y (4260) \to D^{(*)} + D ˉ^{(*)}$ . It is found that in both approches the mode $Y \to Z_{c}^{+} + π^{-}$ is enhanced compared with the open charm modes. However the absolute value of the $Y \to Z_{c}^{+} + π^{-}$ decay width obtained in molecular picture is arguably too large. On the other hand the value obtained in tetraquark picture is reasonable.
Comments:
12 pages, 1 figure
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2003.04142 [pdf]
PRD(2020)·17 citations
09
[Submitted on 9 Mar 2020] (cross-list from hep-ph)
Nuclear shadowing in DIS at electron-ion colliders
Michal Krelina🇨🇱 · Jan Nemchik🇨🇿
We present a revision of predictions for nuclear shadowing in deep-inelastic scattering at small Bjorken $x_{B j}$ corresponding to kinematic regions accessible by the future experiments at electron-ion colliders. The nuclear shadowing is treated within the color dipole formalism based on the rigorous Green function technique. This allows incorporating naturally color transparency and coherence length effects, which are not consistently and properly included in present calculations. For the lowest $∣ q q ˉ ⟩$ Fock component of the photon, our calculations are based on an exact numerical solution of the evolution equation for the Green function. Here the magnitude of shadowing is tested using a realistic form for the nuclear density function, as well as various phenomenological models for the dipole cross section. The corresponding variation of the transverse size of the $q q ˉ$ photon fluctuations is important for $x_{B j} ≳ 1 0^{- 4}$ , on the contrary with the most of other models, which use frequently only the eikonal approximation with the "frozen" transverse size. At $x_{B j} ≲ 0.01$ we calculate within the same formalism also a shadowing correction for the higher Fock component of the photon containing gluons. The corresponding magnitudes of gluon shadowing correction are compared adopting different phenomenological dipole models. Our results are tested by available data from the E665 and NMC collaborations. Finally, the magnitude of nuclear shadowing is predicted for various kinematic regions that should be scanned by the future experiments at electron-ion colliders.
Comments:
Datasets at https://zenodo.org/record/3470138 , fixed figure and misprints
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2003.04156 [pdf]
Eur.Phys.J.Plus(2020)·15 citations

Affiliations

first authorsco-authorsvia INSPIRE

Polarization and Vorticity in the Quark Gluon Plasma

Semi-Inclusive Jet Functions and Jet Substructure in JET​(I)​ and JET​(II)​ Algorithms

Y(4260) as four-quark state

Nuclear shadowing in DIS at electron-ion colliders

Affiliations

Semi-Inclusive Jet Functions and Jet Substructure in $J_{E_{T}}^{(I)}$ and $J_{E_{T}}^{(I I)}$ Algorithms

$Y (4260)$ as four-quark state