arXiv subjects

Yuan-Yuan Zhang

Publications and source records attributed to Yuan-Yuan Zhang.

8 recordsLinked to original sources

arXiv2024

eHIJING: an Event Generator for Jet Tomography in Electron-Ion Collisions

We develop the first event generator, the electron-Heavy-Ion-Jet-INteraction-Generator (eHIJING), for the jet tomography study of electron-ion collisions. In this generator, energetic jet partons produced from the initial hard scattering undergo multiple collisions with the nuclear target. The collision rate is proportional to the transverse-momentum-dependent (TMD) gluon density in the nucleus, which is given by a simple model inspired by the physics of gluon saturation. Medium-modified QCD splitting functions within the higher-twist (HT) and generalized higher-twist (GHT) frameworks are utilized to simulate parton showering in the nuclear medium that takes into account the non-Abelian Landau-Pomeranchuck-Midgal interference effect. Employing eHIJING, we revisit hadron production in semi-inclusive deep inelastic scattering (SIDIS) as measured by EMC, HERMES, and recent CLAS experiments. eHIJING with both GT and GHT frameworks gives reasonably good descriptions of these experimental data. Predictions for experiments at the future electron-ion colliders are also provided. It is demonstrated that future measurements of the transverse momentum broadening of single hadron spectra can be used to map out the two-dimensional kinematic ($Q^2, x_B$) dependence of the jet transport coefficient $\hat{q}$ in cold nuclear matter.

hep-ph↗

arXiv2023

Harmonics of Lepton-Jet Correlations in inclusive and diffractive scatterings

Based on our previous work, we study the harmonic coefficient of both inclusive and diffractive azimuthal angle dependent lepton-jet correlations in Hadron-Electron Ring Accelerator and the future electron-ion collider. Numerical calculations for inclusive and diffractive harmonics and the ratio of harmonics in $e+\text{Au}$~and $e+p$ indicate their strong discriminating power for non-saturation model and saturation model. Additionally, we demonstrate that the t-dependent diffractive harmonics can serve as novel observables for nuclear density profile.

hep-ph↗

arXiv2023

Harmonics of Parton Saturation in Lepton-Jet Correlations at the EIC

Parton saturation is one of the most intriguing phenomena in the high energy nuclear physics research frontier, especially in the upcoming era of the Electron-Ion Collider (EIC). The lepton-jet correlation in deep inelastic scattering provides us with a new gateway to the parton saturation at the EIC. In particular, we demonstrate that azimuthal angle anisotropies of the lepton-jet correlation are sensitive to the strength of the saturation momentum in the EIC kinematic region. In contrast to the predictions based on the collinear framework calculation, significant nuclear modification of the anisotropies is observed when we compare the saturation physics results in e + p and e + Au scatterings. By measuring these harmonic coefficients at the EIC, one can conduct quantitative analysis in different collisional systems and unveil compelling evidence for saturation effects.

hep-ph↗

arXiv2022

Parton rescattering and gluon saturation in dijet production at EIC

Large angle gluon radiations induced by multiple parton scatterings contribute to dijet production in deeply inelastic scattering off a large nucleus at the Electron-Ion Collider. Within the generalized high-twist approach to multiple parton scattering, such contributions at the leading order in perturbative QCD and large Bjorken momentum fraction $x_B$ can be expressed as a convolution of the multiple parton scattering amplitudes and the transverse momentum dependent (TMD) two-parton correlation matrix elements. We study this medium-induced dijet spectrum and its azimuthal angle correlation under the approximation of small longitudinal momentum transfer in the secondary scattering and the factorization of two-parton correlation matrix elements as a product of quark and gluon TMD parton distribution function (PDF). Using a simple model for gluon saturation based on the parametrized gluon TMD PDF, we can calculate the $x_B$ and $Q^2$ dependence of the saturation scale and parton transport coefficient $\hat q$. Contributions to dijet cross section from double scattering are power-suppressed and only become sizable for mini-jets at small transverse momentum. We find that the total dijet correlation for these mini-jets, which also includes the contribution from single scattering, is sensitive to the transverse momentum broadening in the quark TMD PDF at large $x$ and saturation in the gluon TMD PDF at small $x$ inside the nucleus. The correlation from double scattering is also found to increase with the dijet rapidity gap and have a quadratic nuclear-size dependence because of the Landau-Pomeranchuk-Migdal (LPM) interference in gluon emission induced by multiple scattering. Experimental measurements of such unique features in the dijet correlation can shed light on the LPM interference in strong interaction and gluon saturation in large nuclei.

hep-ph↗

arXiv2019

Parton Energy Loss and the Generalized Jet Transport Coefficient

We revisit radiative parton energy loss in deeply inelastic scattering (DIS) off a large nucleus within the perturbative QCD approach. We calculate the gluon radiation spectra induced by double parton scattering in DIS without collinear expansion in the transverse momentum of initial gluons as in the original high-twist approach. The final radiative gluon spectrum can be expressed in terms of the convolution of hard partonic parts and unintegrated or transverse momentum dependent (TMD) quark-gluon correlations. The TMD quark-gluon correlation can be factorized approximately as a product of initial quark distribution and TMD gluon distribution which can be used to define the generalized or TMD jet transport coefficient. Under the static scattering center and soft radiative gluon approximation, we recover the result by Gylassy-Levai-Vitev (GLV) in the first order of the opacity expansion. The difference as a result of the soft radiative gluon approximation is investigated numerically under the static scattering center approximation.

hep-ph↗

arXiv2019

Local-hidden-state models for T-states using finite shared randomness

The study of local models using finite shared randomness originates from the consideration about the cost of classically simulating entanglement in composite quantum systems. We construct explicitly two families of local-hidden-state (LHS) models for T-states, by mapping the problem to the Werner state. The continuous decreasing of shared randomness along with entanglement, as the anisotropy increases, can be observed in the one from the most economical model for the Werner state. The construction of the one for separable states shows that the separable boundary of T-states can be generated from the one of the Werner state, and the cost is 2 classical bits.

quant-ph↗

arXiv2019

Local-hidden-state models for Bell diagonal states and beyond

For a bipartite entangled state shared by two observers, Alice and Bob, Alice can affect the post-measured states left to Bob by choosing different measurements on her half. Alice can convince Bob that she has such an ability if and only if the unnormalized postmeasured states cannot be described by a local-hidden-state (LHS) model. In this case, the state is termed steerable from Alice to Bob. By converting the problem to construct LHS models for two-qubit Bell diagonal states to the one for Werner states, we obtain the optimal models given by Jevtic \textit{et al.} [J. Opt. Soc. Am. B 32, A40 (2015)], which are developed by using the steering ellipsoid formalism. Such conversion also enables us to derive a sufficient criterion for unsteerability of any two-qubit state.

quant-ph↗

arXiv2015

Superconducting properties of sulfur-doped iron selenide

The recent discovery of high-temperature superconductivity in single-layer iron selenide has generated significant experimental interest for optimizing the superconducting properties of iron-based superconductors through the lattice modification. For simulating the similar effect by changing the chemical composition due to S doping, we investigate the superconducting properties of high-quality single crystals of FeSe$_{1-x}$S$_{x}$ ($x$=0, 0.04, 0.09, and 0.11) using magnetization, resistivity, the London penetration depth, and low temperature specific heat measurements. We show that the introduction of S to FeSe enhances the superconducting transition temperature $T_{c}$, anisotropy, upper critical field $H_{c2}$, and critical current density $J_{c}$. The upper critical field $H_{c2}(T)$ and its anisotropy are strongly temperature dependent, indicating a multiband superconductivity in this system. Through the measurements and analysis of the London penetration depth $λ_{ab}(T)$ and specific heat, we show clear evidence for strong coupling two-gap $s$-wave superconductivity. The temperature-dependence of $λ_{ab}(T)$ calculated from the lower critical field and electronic specific heat can be well described by using a two-band model with $s$-wave-like gaps. We find that a $d$-wave and single-gap BCS theory under the weak-coupling approach can not describe our experiments. The change of specific heat induced by the magnetic field can be understood only in terms of multiband superconductivity.

cond-mat.supr-con↗