Search

We outline the physics opportunities provided by the Electron Ion Collider (EIC). These include the study of the parton structure of the nucleon and nuclei, the onset of gluon saturation, the production of jets and heavy flavor, hadron spectroscopy and tests of fundamental symmetries. We review the present status and future challenges in EIC theory that have to be addressed in order to realize this ambitious and impactful physics program, including how to engage a diverse and inclusive workforce. In order to address these many-fold challenges, we propose a coordinated effort involving theory groups with differing expertise is needed. We discuss the scientific goals and scope of such an EIC Theory Alliance., Comment: 44 pages, ReVTeX, White Paper on EIC Theory Alliance

Plenary presentation at DIS2022

We study the small-$x$ evolution equation for the gluon generalized parton distribution (GPD) $E_g$ of the nucleon. It is shown that $E_g$ at vanishing skewness exhibits the Regge behavior identical to the BFKL Pomeron, despite its association with nucleon helicity-flip processes. We also consider the effect of gluon saturation and demonstrate that $E_g$ gets saturated in the same way as its helicity-nonflip counterpart $H_g$. Our result has a direct impact on the modeling of $E_g$ as well as the small-$x$ contribution to nucleon spin sum rules., Comment: 5 pages, 1 figure, v2 matches PRL version

We present a model of exclusive $��$-meson lepto-production $ep \to e'p'��$ near threshold which features the strangeness gravitational form factors of the proton. We argue that the shape of the differential cross section $d��/dt$ is a sensitive probe of the strangeness D-term of the proton., 9 pages

We study sub-threshold heavy quarkonium ($J/��$ and $��$) photo-productions in $��A$ collisions as an independent test of the universality of the nucleon-nucleon short range correlation (SRC) in nuclear scattering processes. Just below the $��p$ threshold, the cross section is dominated by the mean field contribution of nucleons inside the nucleus. The SRC contributions start to dominate at lower photon energies, depending on the fraction of the SRC pairs in the target nucleus. We give an estimate of the cross sections in the sub-threshold region both for $J/��$ and $��$. This may be helpful for future measurements at JLab as well as at the Electron-Ion Collider in the U.S., and especially in China., 7 pages, 5 figures

We update our previous calculation of $J/��$ photo-production near threshold \cite{Hatta:2018ina} by incorporating the recent developments in theory and the new experimental data from the GlueX collaboration at Jefferson Lab \cite{Ali:2019lzf}. We then propose to study the near threshold production of $��$ and $J/��$ in ultraperipheral $pA$ collisions at RHIC. These processes are sensitive to the gluon condensate in the proton which is related to the QCD trace anomaly. Our result emphasizes the role of gluons as the origin of the proton mass., 10 pages, 9 figures

It has been suggested that the production of a heavy quarkonium near threshold in electron-proton scattering can shed light on the origin of the proton mass via the QCD trace anomaly. We study the photoproduction of $J/��$ off the proton using gauge/string duality and demonstrate that the $t$-dependence of the differential cross section $d��/dt$ at small-$t$ is a sensitive probe of the trace anomaly., 17 pages, 7 figures. v2: Eq.(24,27) corrected, minor changes in numerical results

We show that the diffractive forward production of two quarkonia, especially the $��_{cJ}$ and $��_c$ states, in proton-proton or proton-ion collisions can access the Weizs��cker-Williams gluon Wigner distribution of the proton. We use the hybrid factorization approach where the collinear, double gluon PDF is applied for one of the protons and the $k_T$-dependent (Wigner or GTMD) distribution for the other. The production of quarkonia is treated in the NRQCD framework. A particularly concise formula is obtained for double $��_{J=1}$ production., 19 pages, 3 figures

We suggest inclusive hadron production in ultra-peripheral proton-nucleus collisions (UPCs) $p^\uparrow A \to h AX$ as a new channel to investigate single spin asymmetries (SSAs), in particular, to test the assumed dominance of the contribution from twist-three fragmentation functions. The UPC cross sections are obtained by considering the photoproduction limit of semi-inclusive deep inelastic scattering (SIDIS). In particular, we find simple formulas for the polarized UPC cross sections in the collinear twist-three framework. We then numerically calculate the fragmentation contribution to SSA in $p^\uparrow A \to \pi A X$ at $\sqrt{s} = 200$ GeV and find a few percent asymmetry in the forward region., Comment: minor corrections, matches the published version

© 2016 American Physical Society. We investigate the close connection between the quantum phase space Wigner distribution of small-x gluons and the color dipole scattering amplitude, and we propose studying it experimentally in the hard diffractive dijet production at the planned electron-ion collider. The angular correlation between the nucleon recoiled momentum and the dijet transverse momentum probes the nontrivial correlation in the phase space Wigner distribution. This experimental study not only provides us with three-dimensional tomographic pictures of gluons inside high energy protons - it gives a unique and interesting signal for the small-x dynamics with QCD evolution effects.

We compute the inclusive spectrum of produced particles in e+e- annihilation in confining gauge theories that have a gravity dual and show that the momentum distribution exhibits the thermal behavior., Comment: 4 pages, revtex4; v2. discussion slightly expanded

This paper has been withdrawn by the author., Comment: 2pages, 1figure, revtex

We argue that the chiral phase transition and the deconfinement phase transition in finite temperature QCD are just different limits of a single crossover phase transition driven by the lightest scalar field which is a mixture of the glueball and the sigma meson. The key mechanism, the level repulsion between the sigma and the glueball, gives not only a unified description of the finite temperature phase transitions, but also a consistent characterization of the entire QCD phase diagram in the temperature-quark mass plane., 10 pages, 3 figures