The physics case for quarkonium-production studies accessible at the US Electron Ion Collider is described.

This White Paper presents an overview of the current status and future perspective of QCD research, based on the community inputs and scientific conclusions from the 2022 Hot and Cold QCD Town Meeting. We present the progress made in the last decade toward a deep understanding of both the fundamental structure of the sub-atomic matter of nucleon and nucleus in cold QCD, and the hot QCD matter in heavy ion collisions. We identify key questions of QCD research and plausible paths to obtaining answers to those questions in the near future, hence defining priorities of our research over the coming decades.

In 2In 2018, the E12-17-003 experiment was conducted at the Thomas Jefferson National Accelerator Facility (JLab) to explore the possible existence of an nn Lambda state in the reconstructed missing mass distribution from a tritium gas target [K. N. Suzuki et al., Prog. Theor. Exp. Phys. 2022, 013D01 (2022); B. Pandey et al., Phys. Rev. C 105, L051001 (2022)]. As part of this investigation, data were also collected using a gaseous hydrogen target, not only for a precise absolute mass scale calibration but also for the study of Lambda/Sigma(0) electroproduction. This dataset was acquired at Q(2) similar or equal to 0.5 ( GeV/c)(2), W = 2.14 GeV, and theta(c.m)(gamma K) similar or equal to 8 degrees. It covers forward angles where photoproduction data are scarce and a low-Q(2) region that is of interest for hypernuclear experiments. On the other hand, this kinematic region is at a slightly higher Q(2) than previous hypernuclear experiments, thus providing crucial information for understanding the Q(2) dependence of the differential cross sections for Lambda/Sigma(0) hyperon electroproduction. This paper reports on the Q(2) dependence of the differential cross section for the e + p. e ' + K+ + Lambda/Sigma(0) reaction at 0.2-0.8 (GeV/c)(2), and provides comparisons with the currently available theoretical models.

The ECCE detector has been recommended as the selected reference detector for the future Electron-Ion Collider (EIC). A series of simulation studies have been carried out to validate the physics feasibility of the ECCE detector. In this paper, detailed studies of heavy flavor hadron and jet reconstruction and physics projections with the ECCE detector performance and different magnet options will be presented. The ECCE detector has enabled precise EIC heavy flavor hadron and jet measurements with a broad kinematic coverage. These proposed heavy flavor measurements will help systematically study the hadronization process in vacuum and nuclear medium especially in the underexplored kinematic region.

In 2018, the E12-17-003 experiment was conducted at the Thomas Jefferson National Accelerator Facility (JLab) to explore the possible existence of an nnLambda state in the reconstructed missing mass distribution from a tritium gas target [K. N. Suzuki et al., Prog. Theor. Exp. Phys. 2022, 013D01 (2022), B. Pandey et al., Phys. Rev. C 105, L051001 (2022)]. As part of this investigation, data was also collected using a gaseous hydrogen target, not only for a precise absolute mass scale calibration but also for the study of Lambda/Sigma^0 electroproduction. This dataset was acquired at Q^2 0.5 (GeV/c)^2, W=2.14 GeV, and theta_gamma K^c.m. 8 deg. It covers forward angles where photoproduction data is scarce and a low-Q^2 region that is of interest for hypernuclear experiments. On the other hand, this kinematic region is at a slightly higher Q^2 than previous hypernuclear experiments, thus providing crucial information for understanding the Q^2 dependence of the differential cross sections for Lambda/Sigma^0 hyperon electroproduction. This paper reports on the Q^2 dependence of the differential cross section for the e + p -> e' + K^+ + Lambda/Sigma^0 reaction in the 0.2-0.8 (GeV/c)^2, and provides comparisons with the currently available theoretical models.

In 2018, the E12-17-003 experiment was conducted at the Thomas Jefferson National Accelerator Facility (JLab) to explore the possible existence of an $nn\mathrm{\ensuremath{\Lambda}}$ state in the reconstructed missing mass distribution from a tritium gas target [K. N. Suzuki et al., Prog. Theor. Exp. Phys. 2022, 013D01 (2022); B. Pandey et al., Phys. Rev. C 105, L051001 (2022)]. As part of this investigation, data were also collected using a gaseous hydrogen target, not only for a precise absolute mass scale calibration but also for the study of $\mathrm{\ensuremath{\Lambda}}/{\mathrm{\ensuremath{\Sigma}}}^{0}$ electroproduction. This dataset was acquired at ${Q}^{2}\ensuremath{\simeq}0.5$ ${(\mathrm{GeV}/c)}^{2}$, $W=2.14$ GeV, and ${\ensuremath{\theta}}_{\ensuremath{\gamma}\mathrm{K}}^{\mathrm{c}.\mathrm{m}.}\ensuremath{\simeq}{8}^{\ensuremath{\circ}}$. It covers forward angles where photoproduction data are scarce and a low-${Q}^{2}$ region that is of interest for hypernuclear experiments. On the other hand, this kinematic region is at a slightly higher ${Q}^{2}$ than previous hypernuclear experiments, thus providing crucial information for understanding the ${Q}^{2}$ dependence of the differential cross sections for $\mathrm{\ensuremath{\Lambda}}/{\mathrm{\ensuremath{\Sigma}}}^{0}$ hyperon electroproduction. This paper reports on the ${Q}^{2}$ dependence of the differential cross section for the $e+p\ensuremath{\rightarrow}{e}^{\ensuremath{'}}+{K}^{+}+\mathrm{\ensuremath{\Lambda}}/{\mathrm{\ensuremath{\Sigma}}}^{0}$ reaction at $0.2--0.8$ ${(\mathrm{GeV}/c)}^{2}$, and provides comparisons with the currently available theoretical models.

The evaluation of the measurement of double-spin asymmetries for charge-separated pions and kaons produced in deep-inelastic scattering from the proton using the ECCE detector design concept is presented, for the combinations of lepton and hadron beam energies of 5 x 41 GeV2 and 18 x 275 GeV2. The study uses unpolarised simulated data that are processed through a full GEANT simulation of the detector. These data are then reweighted at the parton level with DSSV helicity distributions and DSS fragmentation functions, in order to generate the relevant asymmetries, and subsequently analysed. The performed analysis shows that the ECCE detector concept provides the resolution and acceptance, with a broad coverage in kinematic phase space, needed for a robust extraction of asymmetries. This, in turn, allows for a precise extraction of sea-quark helicity distributions.

Exclusive heavy quarkonium photoproduction is one of the most popular processes in EIC, which has a large cross section and a simple final state. Due to the gluonic nature of the exchange Pomeron, this process can be related to the gluon distributions in the nucleus. The momentum transfer dependence of this process is sensitive to the interaction sites, which provides a powerful tool to probe the spatial distribution of gluons in the nucleus. Recently the problem of the origin of hadron mass has received lots of attention in determining the anomaly contribution $M_{a}$. The trace anomaly is sensitive to the gluon condensate, and exclusive production of quarkonia such as J/$ψ$ and $Υ$ can serve as a sensitive probe to constrain it. In this paper, we present the performance of the ECCE detector for exclusive J/$ψ$ detection and the capability of this process to investigate the above physics opportunities with ECCE.

The recently approved Electron-Ion Collider (EIC) will provide a unique new opportunity for searches of charged lepton flavor violation (CLFV) and other new physics scenarios. In contrast to the $e \leftrightarrow \mu$ CLFV transition for which very stringent limits exist, there is still a relatively large discovery space for the $e \to \tau$ CLFV transition, potentially to be explored by the EIC. With the latest detector design of ECCE (EIC Comprehensive Chromodynamics Experiment) and projected integral luminosity of the EIC, we find the $\tau$-leptons created in the DIS process $ep\to \tau X$ are expected to be identified with high efficiency. A first ECCE simulation study, restricted to the 3-prong $\tau$-decay mode and with limited statistics for the Standard Model backgrounds, estimates that the EIC will be able to improve the current exclusion limit on $e\to \tau$ CLFV by an order of magnitude.

The Electron-Ion Collider (EIC) is a cutting-edge accelerator facility that will study the nature of the "glue" that binds the building blocks of the visible matter in the universe. The proposed experiment will be realized at Brookhaven National Laboratory in approximately 10 years from now, with detector design and R D currently ongoing. Notably, EIC is one of the first large-scale facilities to leverage Artificial Intelligence (AI) already starting from the design and R D phases. The EIC Comprehensive Chromodynamics Experiment (ECCE) is a consortium that proposed a detector design based on a 1.5T solenoid. The EIC detector proposal review concluded that the ECCE design will serve as the reference design for an EIC detector. Herein we describe a comprehensive optimization of the ECCE tracker using AI. The work required a complex parametrization of the simulated detector system. Our approach dealt with an optimization problem in a multidimensional design space driven by multiple objectives that encode the detector performance, while satisfying several mechanical constraints. We describe our strategy and show results obtained for the ECCE tracking system. The AI-assisted design is agnostic to the simulation framework and can be extended to other sub-detectors or to a system of sub-detectors to further optimize the performance of the EIC detector.

We report the first measurements of deep inelastic scattering spin-dependent azimuthal asymmetries in back-to-back dihadron electroproduction in the deep inelastic scattering process. In this reaction, two hadrons are produced in opposite hemispheres along the z axis in the virtual photon-target nucleon center-of-mass frame, with the first hadron produced in the current-fragmentation region and the second in the target-fragmentation region. The data were taken with longitudinally polarized electron beams of 10.2 and 10.6 GeV incident on an unpolarized liquid-hydrogen target using the CLAS12 spectrometer at Jefferson Lab. Observed nonzero sinΔϕ modulations in ep→e^{'}pπ^{+}X events, where Δϕ is the difference of the azimuthal angles of the proton and pion in the virtual photon and target nucleon center-of-mass frame, indicate that correlations between the spin and transverse momenta of hadrons produced in the target- and current-fragmentation regions may be significant. The measured beam-spin asymmetries provide a first access in dihadron production to a previously unexplored leading-twist spin- and transverse-momentum-dependent fracture function. The fracture functions describe the hadronization of the target remnant after the hard scattering of a virtual photon off a quark in the target particle and provide a new avenue for studying nucleonic structure and hadronization.

In a randomized, placebo-controlled phase 2b trial in NSV, the efficacy of the oral JAK3/TEC family kinase inhibitor ritlecitinib with or without a 4-week loading dose (200/50mg, 100/50mg, 50mg, 30mg, 10mg) or placebo for 24 weeks was evaluated in patients with lighter skin (FST I-III) vs darker skin (FST IV-VI); 50mg dose groups (50mg) and 30/10mg (low dose) groups were combined for analysis. Treatment with 50mg ritlecitinib significantly reduced depigmentation extent at Week 24 [W24] vs placebo both in patients with FST I-III (% change from baseline [%CFB] in Facial-Vitiligo Area Scoring Index -15.2,P=0.004) and FST IV-VI (-37.4, P<0.0001). At Week 48, there was no difference in %CFB between FST I-III and FST IV-VI groups (-63.1 vs -66.8). Immune biomarkers were evaluated. Blood collected at baseline, Week 4 [W4], and W24 was analyzed by Olink proteomics cardiovascular, neurology, immuno-oncology, and inflammation target panels. At baseline, patients with FST I-III had elevated levels of serum proteins such as CLM-1 and CSF-1, and patients with FST IV-VI had elevated levels of NOS3. Following ritlecitinib treatment, patients with FST I-III in the 50mg groups had decreased CXCL11 levels from baseline (W24: P=9e-5), while patients with FST IV-VI had increased levels of CXCL11 (W24: P=0.05), IL-10 (W24: P=0.003), and IL-27 (W4: P=0.0007). These results suggest that NSV immune system dysregulation can vary, leading to differential molecular changes in response to JAK3/TEC family kinase inhibition.

We describe the design and performance the calorimeter systems used in the ECCE detector to achieve the overall performance specifications cost-effectively with careful consideration of appropriate technical and schedule risks. The calorimeter systems consist of three electromagnetic calorimeters, covering the combined pseudorapidity range from −3.7 to 3.8 and two hadronic calorimeters covering a combined range of −1.1<η<3.8. Key calorimeter performances which include energy and position resolutions, reconstruction efficiency, and particle identification will be presented.

Background PF-06835375 is a humanised, afucosyl IgG1 antibody selective against C-X-C chemokine receptor type 5 (CXCR5), a receptor expressed on B cells, bona fide T follicular helper (Tfh) cells and circulating T follicular helper-like (cTfh) cells. PF-06835375 is in development for autoimmune diseases through depletion of CXCR5-positive B and Tfh cells and antagonism of C-X-C motif chemokine ligand 13-dependent signalling. Objectives This first-in-human study evaluated the safety, tolerability, pharmacokinetics (PK) and pharmacodynamics (PD) of PF‑06835375 in patients with seropositive systemic lupus erythematosus (SLE) or rheumatoid arthritis (RA). Methods This multi-centre, double-blind, placebo-controlled Phase 1 study enrolled patients aged 18–70 years with seropositive SLE (diagnosed by Systemic Lupus International Collaborating Clinics classification criteria, and positive anti-nuclear antibody titres ≥1:80 and/or anti-dsDNA and/or anti-Smith antibodies) or RA (diagnosed by 2010 ACR/EULAR criteria and positive rheumatoid factor and/or anti-citrullinated peptide antibody), with no minimum disease activity requirement. Patients were randomised to intravenous (IV) PF-06835375 (0.03, 0.1, 0.3, 1, 3 or 6 mg) or placebo in 6 sequential single ascending dose (SAD) cohorts, or to subcutaneous (SC) PF‑06835375 (0.3, 1, 3, 6 or 10 mg) or placebo administered on Days 1 and 29 in 5 multiple ascending dose (MAD) cohorts. Pre-and post-dose corticosteroids were permitted to manage infusion or injection reactions at the investigator’s discretion. Primary endpoints were incidence of treatment-emergent adverse events (TEAEs) of all casualties, infections and laboratory, vital sign and electrocardiogram (ECG) abnormalities. Secondary endpoints were PK parameters, change in circulating CXCR5-positive B- and cTfh-cell counts and incidence of anti-drug antibodies (ADAs). Results In total, 74 patients were randomised and 73 were treated (SAD cohorts: SLE, n=17; RA, n=14; MAD cohorts: SLE, n=22; RA, n=20). Corticosteroids were given in PF-06835375 3 and 6 mg IV cohorts and 3, 6 and 10 mg SC cohorts. Mean (standard deviation) age was 53.3 (10.7) years. Most patients were female (n=65, 89.0%) and White (n=54, 74.0%). In total, 62 patients (84.9%) experienced TEAEs; most were mild or moderate. Serious adverse events were reported in 3 patients (9.7%). One patient (1.4%) discontinued due to a TEAE of disease progression (placebo SC cohort). The most common TEAEs were headache (n=18, 24.7%), pyrexia (n=11, 15.1%) and urinary tract infection (n=9, 12.3%). All infections were mild or moderate. Laboratory abnormalities (placebo IV SAD, PF-06835375 1 mg IV SAD and PF‑06835375 3 mg SC MAD) and ECG abnormalities (PF-06835375 0.1, 1 and 6 mg IV SAD) were reported as TEAEs in individual patients. No deaths occurred. In IV SAD cohorts, median Tmax ranged from 2–4 h and mean CL ranged from 0.021–0.313 L/h. Exposure (AUCinf and Cmax) generally increased dose-proportionally for doses ≤1 mg and more than dose‑proportionally for doses >1 mg. In SC MAD cohorts, median Tmax ranged from 121–171 h and mean CL/F ranged from 0.07847–0.1171 L/h. Exposure (AUCtau and Cmax) generally increased dose-proportionally. B- and cTfh-cell counts generally showed dose-dependent reductions across cohorts (range of mean maximum depletion: 67.3–99.3% and 62.4–98.7%, respectively, in SAD, and 91.1–99.6% and 89.5–98.1%, respectively, in MAD cohorts; Figure 1). Mean duration of B- and cTfh-cell depletion extended up to 71.6 and 62.0 days, respectively, in SAD, and 78.5 and 109.5 days, respectively, in MAD cohorts. ADA data did not suggest any clinically relevant impact on PK, PD or safety. Conclusion PF-06835375 was generally well tolerated in patients with seropositive SLE and RA with potent and prolonged B- and cTfh-cell depletion, supporting further development as a treatment for autoimmune diseases. Acknowledgements This study was sponsored by Pfizer Inc. Medical writing support, under the direction of the authors, was provided by Sonya Frazier, PhD, CMC Connect, a division of IPG Health Medical Communications, and was funded by Pfizer Inc, New York, NY, USA, in accordance with Good Publication Practice (GPP 2022) guidelines (Ann Intern Med 2022; 175: 1298-1304). Disclosure of Interests Stanley Cohen Consultant of: Pfizer Inc, Jean Beebe Employee of: Former employee of Pfizer Inc, Vishala Chindalore: None declared, Shunjie Guan Employee of: Employee of Pfizer Inc, Mina Hassan-Zahraee Employee of: Employee of Pfizer Inc, Craig Hyde Employee of: Employee of Pfizer Inc, Sarita Koride Employee of: Employee of Pfizer Inc, Robert Levin Speakers bureau: AbbVie and GlaxoSmithKline, Consultant of: AbbVie, AstraZeneca and Janssen, Shannon Lubaczewski Employee of: Employee of Pfizer Inc, Mikhail Salganik Employee of: Employee of Pfizer Inc, Abigail Sloan Employee of: Employee of Pfizer Inc, Erin Stevens Employee of: Employee of Pfizer Inc, Elena Peeva Employee of: Employee of Pfizer Inc, Michael Vincent Shareholder of: Pfizer Inc, Employee of: Employee of Pfizer Inc, David Martin Employee of: Employee of Pfizer Inc, Myron Chu Employee of: Employee of Pfizer Inc.

We performed feasibility studies for various measurements that are related to unpolarized TMD distribution and fragmentation functions for the ECCE detector proposal. The processes studied include semi-inclusive Deep inelastic scattering (SIDIS) where single hadrons (pions and kaons) were detected in addition to the scattered DIS lepton. The single hadron cross sections and multiplicities were extracted as a function of the DIS variables x and Q(2), as well as the semi-inclusive variables z, which corresponds to the momentum fraction the detected hadron carries relative to the struck parton and P-T which corresponds to the transverse momentum of the detected hadron relative to the virtual photon. The expected statistical precision of such measurements is extrapolated to accumulated luminosities of 10 fb(-1) and potential systematic uncertainties are approximated given the deviations between true and reconstructed yields. The expected uncertainties are then used to obtain the expected impact on the related TMD distribution and fragmentation functions. We find that the ECCE detector proposal fulfills the physics requirements on these channels as detailed in the EIC Yellow Report.

We report the first measurement of $x_B$-scaling in $(e,e'p)$ cross-section ratios off nuclei relative to deuterium at large missing-momentum of $350 \leq p_{miss} \leq 600$ MeV/c. The observed scaling extends over a kinematic range of $0.7 \leq x_B \leq 1.8$, which is significantly wider than $1.4 \leq x_B \leq 1.8$ previously observed for inclusive $(e,e')$ cross-section ratios. The $x_B$-integrated cross-section ratios become constant (i.e., scale) beginning at $p_{miss}\approx k_F$, the nuclear Fermi momentum. Comparing with theoretical calculations we find good agreement with Generalized Contact Formalism calculations for high missing-momentum ($> 375$ MeV/c), suggesting the observed scaling results from interacting with nucleons in short-range correlated (SRC) pairs. For low missing-momenta, mean-field calculations show good agreement with the data for $p_{miss}\le k_F$, and suggest that contributions to the measured cross-section ratios from scattering off single, un-correlated, nucleons are non-negligible up to $p_{miss}\approx 350$ MeV/c. Therefore, SRCs become dominant in nuclei at $p_{miss}\approx 350$ MeV/c, well above the nuclear Fermi Surface of $k_F \approx 250$ MeV/c.

This article presents a collection of simulation studies using the ECCE detector concept in the context of the EIC's exclusive, diffractive, and tagging physics program, which aims to further explore the rich quark-gluon structure of nucleons and nuclei. To successfully execute the program, ECCE proposed to utilize the detecter system close to the beamline to ensure exclusivity and tag ion beam/fragments for a particular reaction of interest. Preliminary studies confirmed the proposed technology and design satisfy the requirements. The projected physics impact results are based on the projected detector performance from the simulation at 10 or 100 fb^-1 of integrated luminosity. Additionally, a few insights on the potential 2nd Interaction Region can (IR) were also documented which could serve as a guidepost for the future development of a second EIC detector.