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Welcome to the EIC Early Career Workshop 2021!
Check us out on the twitter: https://twitter.com/ion_early
Meeting Zoom link: https://cwm.zoom.us/j/97224327244?pwd=TFAybkNpWmltTW90NHF4ODR6dTZ4dz09
Meeting ID: 972 2432 7244
Passcode: 1111
I will present a developing research activity for an application of a harmonic kicker to a RCS injection scheme of the EIC.
The use of organic scintillating fibre arrays with opto-electronics devices combines the fast response of scintillating detectors with the granularity of tracking devices and the advantage of reduced cost and relatively simple construction. In this talk, I will present examples of this detector and potential uses of it in the EIC.
The Timing Optimized PID Silicon Detector for the EIC (TOPSiDE) is Argonne's proposed central detector concept for the Electron-Ion Collider, with its physics goals of perturbative and non-perturbative Quantum ChromoDynamics (QCD) studies of the structure of nucleons and nuclei. It requires high precision tracking, good vertex resolution, and excellent particle identification with a timing resolution of around 10 ps or better. TOPSiDE uses Ultra-Fast Silicon Detectors (UFSD) based on the Low-Gain Avalanche Detector (LGAD) technology. The LGADs are proven to provide timing resolutions of a few 10s of picoseconds. I will present the results of 35 $\mu$m and 50 $\mu$m thick DC-LGAD tests at Fermilab Test Beam Facility with 120 GeV proton beam. The best timing resolution of DC-LGADs in a test beam to date is achieved using three combined planes of 35 $\mu$m thick LGADs at -30 $^\circ$C with a precision of 14.3 $\pm$ 1.5 ps. The latest test measurements of AC-LGADs using single-channel and multichannel read-outs will also be presented.
Excellent particle identification (PID) is one of the key requirements for the central detector of the Electron-Ion collider (EIC). Identification of the hadrons in the final state is important to study how different quark flavors contribute to nucleon properties. A detector with a radial size of only 7-8 cm, which uses the principle of Detection of Internally Reflected Cherenkov light (DIRC), is a very attractive solution to meet these requirements. The R$\&$D program performed by the EIC PID collaboration (eRD14) is focused on developing a high-performance DIRC (hpDIRC) detector that would primarily extend the momentum coverage well beyond the state-of-the-art 3 standard deviations or more separation of $\pi/K$ up to at least 6 GeV/$c$ in the polar angle range $30^{\circ}-145^{\circ}$. Additionally it is expected to provide separation power for p/K up to 10 GeV/$c$, and low momentum e/$\pi$. The key element of the hpDIRC detector is a custom-made 3-layer compound lens used to focus Cherenkov photons produced by charged tracks to small pixel-size photo-sensors leading to measure the position and time of the photons with great precision and finally identify the charged particle. In this talk an overview of the hpDIRC detector development will be presented as an example of wide range of research opportunities during the R$\&$D phase.
Understanding the modification of quarks in nucleons within nuclei (EMC effect) is a longstanding open question in nuclear physics. Recent experimental results from electron scattering at Jefferson Lab strengthen the correlation between the EMC effect and nucleon-nucleon short-range correlated pairs (SRC) within nuclei. That means that the EMC effect is probably driven by the high-momentum highly-virtual nucleons of the SRC pairs. This connection can be tested experimentally by measuring electron deep inelastic scattering (DIS) from a nucleon and detecting its correlated SRC partner nucleon (tagging). The Electron-Ion-Collider (EIC) is an ideal machine for tagging measurements due to unique capability of measuring recoil nucleons compared to fixed-target experiments. The design of the EIC detectors allows for a full acceptance for forward-going protons, neutrons and nuclear fragments in addition to the scattered electron.
In my talk, I will present results from simulation studies of tagged short-range correlations in Quasi-elastic kinematics at the EIC. The results will show the achievable statistics and tagging capabilities for tagged SRC physics at the EIC.
We study the diffractive dissociation of a virtual photon in the scattering off a large nucleus at high energies in the QCD dipole picture in which the photon is conveniently represented by an onium. In a well-defined parametric regime, the nuclear scattering of the onium is triggered by large-dipole fluctuations in the course of its rapidity evolution in the form of color dipole branching, and the diffractive dissociation with a minimal gap $Y_0$ is tantamount to the probability that an even number of the dipoles in the onium Fock state effectively participates in the scattering, in a frame in which the onium is evolved to the rapidity $Y−Y_0$ out of the total relative rapidity $Y$. Such picture allows to extract the asymptotic solution to the Kovchegov-Levin equation, established in QCD 20 years ago, which rules the diffractive cross section. Diffraction in electron-ion collisions, which can be linked to the same process in onium-nucleus scattering, is then studied based on numerical solutions of the original Kovchegov-Levin equation and of its next-to-leading extension taking into account the running of the strong coupling, with the aim to make predictions for the distribution of rapidity gaps in realistic kinematics of future electron-ion colliders. We show that the fixed and the running coupling equations lead to different distributions, rather insensitive to the chosen prescription in the running coupling case. The obtained distributions for the fixed coupling framework exhibit a shape characteristic of the above-mentioned picture already at rapidities accessible at future electron-ion colliders, which demonstrates the relevance of measurements of such observables for the microscopic understanding of diffractive dissociation in QCD.
The spin structure function of the neutron is traditionally determined by measuring the spin asymmetry of inclusive electron deep inelastic scattering (DIS) off polarized 3He nuclei. In such experiments, nuclear corrections are significant and must be treated carefully in the interpretation of experimental data. Here we study the feasibility of suppressing model dependencies by tagging both spectator protons in the process of DIS off neutrons in 3He at the forthcoming Electron-Ion Collider (EIC). This allows for a reconstruction of the momentum of the struck neutron to ensure it was nearly at rest in the initial state, thereby reducing sensitivity to nuclear corrections and suppressing contributions from electron DIS off protons in 3He. Using realistic accelerator and detector configurations, we demonstrate that the EIC can probe the neutron spin structure from xB of 0.003 to 0.651. We find that the double spectator tagging method results in reduced uncertainties by a factor of 4 on the extracted neutron spin asymmetries over all kinematics and by a factor of 10 in the low-xB region, thereby providing valuable insight into the spin and flavor structure of nucleons.
Quantum chromodynamics degrees of freedom are proposed to explain various puzzling results in nuclear physics. The 1983 EMC experiment discovery of unexpected quark behavior in nuclei has been investigated in great depth both experimentally and theoretically since that time. The viability of quark-quark bonds across nucleons provides an explanation for unusual quark behavior when the quark home nucleon is embedded in a nucleus. Predictions for the isospin values of nucleon-nucleon pairs are given and the spin dependence of diquark bonds in nuclei is quantified.
The Electron-Ion Collider (EIC) to be built at Brookhaven National Laboratory is a high luminosity accelerator facility colliding polarized electron beam with different ion species ranging from lighter nuclei (proton, deuterium) to heavier nuclei (gold, uranium). Design of a stripline injection kicker for the Hadron Storage Ring (HSR) of EIC for beams with beam rigidity of 81 T-m poses some technical challenges due to expected high feedthrough voltages, short bunch spacing, and high peak current of EIC. This talk will focus on the optimization of the stripline injection kicker. Starting from the 2D cross-section design which includes the selection of electrodes shape, we describe the optimization of the kicker's cross-section and the techniques that we employed to optimize its 3D geometry. In addition, we present the simulation results for the beam coupling impedance and Time Domain Reflection (TDR). Finally, we will show the maximum surface electric field corresponds to the feedthrough voltage we require and the surface heating due to the circulating beam.
The space and momentum distribution of hadronic constituents (gluons, sea quarks) inside the nucleon is of utmost importance in studies of QCD. Deeper considerations of the lightest mesons (pions, kaons) could provide insights into many questions that plague modern QCD studies. Pions and Kaons are connected to the Goldstone modes of dynamical chiral symmetry breaking, making them critical components in understanding the origin of hadronic mass. The Electron-Ion Collider (EIC) will provide access to a large kinematic range in the longitudinal momentum fraction, x, and the four-momentum transfer, Q2 . These would allow the extraction of structure functions and the pion and kaon form factors. Such measurements would allow one to probe the differences of gluon content in pions, kaons, and nucleons. The difference in gluon content may be the origin of the differences in these hadron masses. While the EIC is under development, Monte Carlo simulations are a quick and effective approach for feasibility studies of measurements in a particular region of interest to theoretical calculations. Specifically, simulations of the pion and kaon structure functions will provide feedback on the feasibility of studying the different gluon content and hadronic structure at large values of x. The EIC will have the capacity to host two interaction regions, each with a corresponding detector. It is expected that each of these two detectors would be represented by a Collaboration. Meson structure function studies are the main driver for far-forward region design. During the EIC YR, optimization of the first beamline was done. The second beamline is only now undergoing a more detailed design and may be even better suited for meson structure studies - in particular, the kaon final state. I will be discussing the optimization of these beamlines and contributions to the PDF global fitting community.
The description of hadronic structure in terms of quark and gluon degrees of freedom is an open subject in physics. Great efforts are being devoted to it on both the theoretical and experimental sides. Triggered by existing plans to build new experimental facilities, and the need to properly interpret the data that are to come, interest into the zoology of parton distribution functions is increasing. Among them, GPDs, which are known to parametrize the soft-physics taking place in DVCS, are expected to play a central role drawing three-dimensional images of hadrons. In this work we focus on the study of pions, which, as Nambu-Goldstone bosons of QCD chiral symmetry breaking, provide one of the clearest windows onto the phenomenon of emergent hadronic mass (EHM). Herein we present a novel class of pion off-forward parton distributions (GPDs) which, relying on the covariant-extension, fulfill all of the theoretical constraints required by QCD. We analyse the effect of scale-evolution, showing that gluon content plays a dominant role into the description of pion's response to Compton scattering (CFFs). Finally, we exploit our models to obtain predictions for DVCS on pions, which is to be probed through the Sullivan process at the foreseen EIC. We show that a measurable asymmetry arise on that channel, therefore pushing optimism about probing pion's structure at future electron-ion colliders.
Studying the role of gluonic observables in exclusive scattering processes is essential as new physics programs, such as an electron ion collider, are planned in unprecedented kinematic regimes. We present a parameterization of gluon generalized parton distributions (GPDs) calculated using a reggeized spectator model. This parameterization is constrained using a combination of lattice QCD form factor calculations and extracted deep inelastic parton distributions. We evolve our parameterization at leading order in Q2 to the scale of experimental data using a perturbative QCD evolution framework. We demonstrate expected spatial distributions under Fourier transformation using our parametrization. Understanding the behavior of gluon GPDs is a first step towards extracting the gluon contribution to deeply virtual Compton scattering (DVCS) and timelike Compton scattering (TCS) observables. This work was funded by DOE grant DE-SC0016286 and SURA grant C2020-FEMT-002-04 and C2021-FEMT-006-05.
The recent exclusive backward-angle electroproduction of omega from Jefferson Lab Hall C electron-proton fixed-target scattering experiments above the resonance region hints at a new domain of applicability of QCD factorization in a unique u-channel kinematics regime. Thanks to this pioneering effort, the interest in studying nucleon structure through u-channel meson production observables has grown significantly. In this presentation, I will provide an overview of a recently completed feasibility study of u-channel pi0 exclusive production at the future Electron-Ion Collider, as it further extends the kinematics coverage beyond the JLab 12 GeV.
Backward ($u$-channel) production of vector mesons in electron-ion collisions is an under-studied mechanism with interesting physics implications. Backward-production reactions are characterized by a small Mandelstam $u$ compared to forward production's small Mandelstam $t$. The result of this difference in reaction channels is that the products of backward production are a proton at mid-rapidity and a vector meson in the forward direction. Data from fixed-target experiments currently constrain backward production kinematics, and experiments at the EIC will have the opportunity to probe this reaction channel with high statistics over a large energy range. The kinematics of backward vector meson production and vector meson decay daughters at the EIC will be discussed. eSTARlight is a Monte Carlo event generator which simulates vector meson production in electron-ion collisions. Recent modifications to eSTARlight which model backward vector meson production and vector meson decays will be presented. Insights from eSTARlight on challenges for EIC detectors to probe backward production will also be shown.
We perform the first simultaneous global QCD extraction of the transverse momentum dependent (TMD) parton distribution functions and the TMD fragmentation functions in nuclei. This analysis allows us to extract the three-dimensional information of the partonic structure of nuclei as well as the three-dimensional information for hadron formation in a nuclear medium. In this analysis, we take into account the world data from semi-inclusive electron-nucleus deep inelastic scattering and Drell-Yan type di-lepton production in proton-nucleus collisions, comprising a total of 126 data points from 6 data sets with $\chi^2/dof = 1.045$. We quantify for the first time the broadening of partonic distributions in nuclei comparing with those in free nucleons. We also make predictions for the ongoing JLab 12 GeV program and future EIC measurements, which are expected to further constrain the three-dimensional partonic structure of nuclei.
We present explorative analyses of the 3D gluon content of the proton via a study of polarized T-odd gluon TMDs at twist-2, calculated in a spectator model for the parent nucleon. Our approach encodes a flexible parameterization for the spectator-mass density, suited to describe both moderate and small-x effects. All these prospective developments are relevant in the investigation of the gluon dynamics inside nucleons and nuclei, which constitutes one of the major goals of the EIC program.
Heavy quark production in deep inelastic scattering proceeds via the Boson Gluon Fusion process and thus are ideal tools to constrain the gluon distribution functions in the nucleon/ion probed. Measurement of heavy flavor hadron pair production in deep inelastic scattering processes provides access to the transverse kinematics of the gluon and provide unique constraints to the gluon transverse momentum dependent distributions (TMDs), particularly in the high Bjorken x ($x_B >$ 0.01) regions. In this talk we will discuss the performance of a tagging algorithm for heavy flavor hadrons, utilizing the displaced tracks from the heavy flavor decays with the excellent track pointing resolution capabilities provided by an all Silicon tracker detector design. We will also discuss performance of exclusive reconstruction of heavy flavor hadron decays with the all Silicon tracker. Projections made on the gluon TMD measurements at a future EIC experiment with these tagging and reconstruction performances will also be discussed.
Measurements of hard probes such as heavy flavor in deep inelastic scatterings will be an essential component to the EIC physics program and are one of the detector R\&D driving aspects. In this talk we will present the projected statistical precision of open charm hadron production through exclusive hadronic channel reconstruction with a silicon detector concept currently being developed using a PYTHIA-based simulation. We further study the impact of possible intrinsic charm in the proton on projected data, and estimate the constraint on the nuclear gluon parton distribution function (PDF) from the charm structure functions $F_{2}^{c\overline{c}}$ in $e$+Au collisions using a Bayesian PDF re-weighting technique.
To study quantum properties of the hadron wavefunction at small x, we derived the reduced density matrix for soft gluons in the CGC framework. We explicitly showed that the reduced density matrix is not diagonal in the particle number basis. The off-diagonal components are usually ignored in the conventional parton model. We thus defined the density matrix of ignorance by keeping only the part of the reduced density matrix which can be probed in a limited set of experimental measurements. We calculated Von Neumann entropy for both the reduced and ignorance density matrices. The entropy of ignorance is always greater than the entanglement entropy (computed drom the reduced density matrix) of gluons. Finally, we showed that the CGC reduced density matrix for soft gluons can be diagonalized in a thermal basis with Boltzmann weights suggesting thermalization of new quasi-particle states.
Using the CGC effective theory together with the hybrid factorisation, we study forward dijet production in proton-nucleus collisions beyond leading order. In this paper, we compute the "real" next-to-leading order (NLO) corrections, i.e. the radiative corrections associated with a three-parton final state, out of which only two are being measured. To that aim, we start by revisiting our previous results for the three-parton cross-section presented in our previous paper. After some reshuffling of terms, we deduce new expressions for these results, which not only look considerably simpler, but are also physically more transparent. We also correct several errors in this process. The real NLO corrections to inclusive dijet production are then obtained by integrating out the kinematics of any of the three final partons. We explicitly work out the interesting limits where the unmeasured parton is either a soft gluon, or the product of a collinear splitting. We find the expected results in both limits: the B-JIMWLK evolution of the leading-order dijet cross-section in the first case (soft gluon) and, respectively, the DGLAP evolution of the initial and final states in the second case (collinear splitting). The "virtual" NLO corrections to dijet production will be presented in a subsequent publication.
Quick summery:
https://www.youtube.com/watch?v=yBjd2HA51yE&ab_channel=DIS2021
The internal structure of jets has been an active research topic in QCD in recent years. In this talk, we propose to use one particular jet substructure - the so-called jet fragmentation function to study spin-dependent distribution and dynamics. In particular, we provide the general theoretical framework for studying the distribution of hadrons inside a jet by taking full advantage of the transverse-momentum-dependent distributions and polarization effects. The key development referred to as “polarized jet fragmentation functions’’, opens up new opportunities to study transverse momentum dependent (TMD) fragmentation functions via jets. Besides providing the theoretical understanding for the well-known Collins asymmetry for hadron in a jet, we also give additional examples involving polarization of Lambda baryons and pions inside the jet at the future Electron-Ion Collider.
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). 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.
In high energy collisions, heavy quarks (c, b) are predominately produced in the initial hard scattering process. The relative ratio of different heavy flavor hadrons species serves as a tool to study charm quark hadronization mechanism. Recently, data from $p$+$p$, $p$+A, and A+A collisions at RHIC and LHC showed that the $\Lambda_c^+/D^0$ ratio is considerably larger than the fragmentation baseline. The high luminosity e+p and e+A collisions in the future Electron-Ion Collider (EIC) at Brookhaven National Laboratory would allow us to systematically investigate the $\Lambda_c$ production over a broad kinematic region, which will shed detail insights on charm hadrochemistry and charm-quark hadronization.
In this talk, I will present the reconstruction capability study for $\Lambda_c^+$ baryons at the future EIC experiment utilizing an all silicon tracker based on next generation MAPS technology. Physics projections on the measurement of $\Lambda_c^+/D^0$ ratio in e+p and e+A collisions in the future EIC will be presented. I will also discuss the physics potentials towards understanding the nucleon/nuclei structure and cold nuclear matter effects enabled by the $\Lambda_c^+$ measurements at EIC.
We studied the use of machine learning to reconstruct deep inelastic scattering (DIS) kinematics. In particular, we trained deep neural networks to reconstruct $x$ and $Q^2$ based on information from the lepton and the hadronic system in ep scattering at the ZEUS experiment at HERA. These models were trained by a careful selection of Monte Carlo events. The results from the neural networks were compared to those of classical reconstruction methods, including the electron method, the Jacquet-Blondel Method, and the double-angle method. The classical methods only consider partial information from an event, each method has its limitations, including a sensitivity to initial and final state QED radiation, a requirement of precise energy measurements, and/or a poor resolution on different kinematic regions. The neural networks trained in our study reconstruct event kinematics based on the information used in the classical methods, but, in addition, are enhanced through correlations and patterns revealed in the simulated data sets from event generators. We show that, with the appropriate selection of a training set, data enhances the neural networks sufficiently to outperform all classical reconstruction methods on most of the kinematic range considered.
We present the results of a comprehensive new Monte Carlo analysis of high-energy lepton-lepton, lepton-hadron and hadron-hadron scattering data to simultaneously determine parton distribution functions (PDFs) in the proton and parton to hadron fragmentation functions (FFs).
DIS in electron-ion collisions provides detailed information on nuclear parton distribution and the partonic dynamics and hadronization in the cold nuclear matter. A general-purpose event generator that accounts for in-medium parton dynamics in DIS benefits both phenomenological study and experimental design. In the eHIJING-1.0 model currently under development, we use Pythia8 to generate initial hard collisions. The struck quark undergoes multiple collisions in the cold nuclear medium. We model the in-medium collision kernel by a saturation-motivated transverse-momentum dependent (TMD) gluon distribution function. In particular, the TMD distribution and saturation scale are determined self-consistently and results in an $x_B$ and $Q^2$ dependence of the jet-transport parameter. Medium-induced parton emission, using either the collinear higher-twist or the generalized higher-twist formula, is added to the $p_T$-ordered parton shower of Pythia8. Finally, we account for medium-modified fragmentation by allowing induced gluon emissions at low-virtuality before hadronization takes place. We tune and validate that the eHIJING model provides a satisfactory description for hadron multiplicities in e-A collisions at the HERMES experiment. We make further predictions for future EIC.