arXiv subjects

J. Jia

Publications and source records attributed to J. Jia.

24 records · Page 2Linked to original sources

arXiv2009

Scaling patterns of the suppression of $π^0$ yields in Au+Au collisions at $\sqrt{s_{NN}}=200$ GeV: links to the transport properties of the QGP

Suppression measurements for neutral pions ($π^0$) are used to investigate the predicted path length ($L$) and transverse momentum ($p_T$) dependent jet quenching patterns of the hot QCD medium produced in Au+Au collisions at $\sqrt{s_{NN}}=200$ GeV. The observed scaling patterns show the predicted trends for jet-medium interactions dominated by radiative energy loss. They also allow simple estimates of the transport coefficient $\hat{q}$ and the ratio of viscosity to entropy density $η/s$. These estimates indicate that the short mean free path ($λ$) in the QCD medium leading to hydrodynamic-like flow with a small value of $η/s$, is also responsible for the strong suppression observed.

nucl-ex↗

arXiv2009

Energy loss for heavy quarks in relation to light partons; is radiative energy loss for heavy quarks anomalous?

The scaling properties of jet suppression measurements are compared for non-photonic electrons ($e^{\pm}$) and neutral pions ($π^0$) in Au + Au collisions at $\sqrt{s_{NN}}=200$ GeV. For a broad range of transverse momenta and collision centralities, the comparison is consistent with jet quenching dominated by radiative energy loss for both heavy and light partons. Less quenching is indicated for heavy quarks via $e^{\pm}$; this gives an independent estimate of the transport coefficient $\hat{q}$ that agrees with its magnitude obtained from quenching of light partons via $π^0$'s.

nucl-ex↗

arXiv2009

Radiative Corrections in Vector-Tensor Models

We consider a two-form antisymmetric tensor field ϕminimally coupled to a non-abelian vector field with a field strength F. Canonical analysis suggests that a pseudoscalar mass term \frac{μ^2}{2} \tr (ϕ\wedge ϕ) for the tensor field eliminates degrees of freedom associated with this field. Explicit one loop calculations show that an additional coupling m\tr(ϕ\wedge F) (which can be eliminated classically by a tensor field shift) reintroduces tensor field degrees of freedom. We attribute this to the lack of the renormalizability in our vector-tensor model. We also explore a vector-tensor model with a tensor field scalar mass term \frac {μ^2}{2} \tr (ϕ\wedge\star ϕ) and coupling m\tr(ϕ\wedge \star F). We comment on the Stueckelberg mechanism for mass generation in the Abelian version of the latter model.

hep-th↗

arXiv2008

Crystallinity and Crystallographic Texture in Isotactic Polypropylene during Deformation and Heating

The development of the crystallinity and of the crystallographic orientation of isotactic polypropylene (iPP) during rolling deformation and subsequent heat treatment is studied. The experiments are conducted by using X-ray diffraction with an area detector. The evolution of crystallographic orientation is tracked by calculating the pole figures and by applying a quantitative 3D texture component fit method. The rolling orientation after a true strain of -1.5 mainly consists of the (010)[001], (130)[001], and [001]//RD fiber components (RD: rolling direction). The results reveal that the crystallinity drastically decreases during rolling. We suggest that decrystallization (disaggregation) is a deformation mechanism which takes place as a microscopic alternative to crystallographic intralamellar shear depending on the orientation of the lamellae relative to the imposed deformation tensor. Heat treatment after rolling leads to the recrystallization of amorphous material and to a strong enhancement of the fiber orientation component. The recrystallization orientation is explained in terms of an oriented nucleation mechanism where amorphous material aligns along existing crystalline lamellae blocks which prevailed during the preceding deformation.

cond-mat.soft↗

arXiv2008

An estimate for the location of QCD critical end point

It is proposed that a study of the ratio of shear viscosity to entropy density $\fracη{s}$ as a function of the baryon chemical potential $μ_B$, and temperature T, provides a dynamic probe for the critical end point (CEP) in hot and dense QCD matter. An initial estimate from an elliptic flow excitation function gives $μ^{\text{cep}}_B \sim 150-180$ MeV and $T_{\text{cep}} \sim 165 - 170$ MeV for the location of the the CEP. These values place the CEP in the range for "immediate" validation at RHIC.

nucl-ex↗

arXiv2002

Charged Hadron Spectra in PHENIX

PHENIX has measured transverse momentum spectra of charged particles at mid-rapidity up to 10 GeV/c in Au+Au collisions at sqrt{s}=200 GeV. For central collisions, the yield at high pT is significantly suppressed comparing to binary scaled p+p data, and this suppression is stronger than observed at 130 GeV. Above 4 GeV/c, the deficit of high momentum particles is almost independent of pT.

nucl-ex↗