Measurements of the EMC effect in the tritium and helium-3 mirror nuclei are reported. The data were obtained by the MARATHON Jefferson Lab experiment, which performed deep inelastic electron scattering from deuterium and the three-body nuclei, using a cryogenic gas target system and the high resolution spectrometers of the Hall A Facility of the Lab. The data cover the Bjorken x range from 0.20 to 0.83, corresponding to a squared four-momentum transfer Q^{2} range from 2.7 to 11.9  (GeV/c)^{2}, and to an invariant mass W of the final hadronic state greater than 1.84  GeV/c^{2}. The tritium EMC effect measurement is the first of its kind. The MARATHON experimental results are compared to results from previous measurements by DESY-HERMES and JLab-Hall C experiments, as well as with few-body theoretical predictions.

Inclusive electron scattering at carefully chosen kinematics can isolate scattering from the high-momentum nucleons in short-range correlations (SRCs). SRCs are produced by the hard, short-distance interactions of nucleons in the nucleus, and because the two-nucleon (2N) SRCs arise from the same N-N interaction in all nuclei, the cross section in the SRC-dominated regime is identical up to an overall scaling factor. This scaling behavior has been used to identify SRC dominance and to measure the contribution of SRCs in a wide range of nuclei. We examine this scaling behavior over a range of momentum transfers using new data on ^2H, ^3H, and ^3He, and find an expanded scaling region compared to heavy nuclei. Motivated by this improved scaling, we examine the ^3H and ^3He data in kinematics where three-nucleon SRCs may play an important role. The data for the largest struck nucleon momenta are consistent with isolation of scattering from three-nucleon SRCs, and suggest that the very highest momentum nucleons in ^3He have a nearly isospin-independent momentum configuration.

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.

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.

The electromagnetic form factors of the proton and neutron encode information on the spatial structure of their charge and magnetization distributions. While measurements of the proton are relatively straightforward, the lack of a free neutron target makes measurements of the neutron's electromagnetic structure more challenging and more sensitive to experimental or model-dependent uncertainties. Various experiments have attempted to extract the neutron form factors from scattering from the neutron in deuterium, with different techniques providing different, and sometimes large, systematic uncertainties. We present results from a novel measurement of the neutron magnetic form factor using quasielastic scattering from the mirror nuclei ^3H and ^3He, where the nuclear effects are larger than for deuterium but expected to largely cancel in the cross-section ratios. We extracted values of the neutron magnetic form factor for low-to-modest momentum transfer, 0.6<Q^2<2.9 GeV^2, where existing measurements give inconsistent results. The precision and Q^2 range of this data allow for a better understanding of the current world's data, and suggest a path toward further improvement of our overall understanding of the neutron's magnetic form factor.

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 nuclear dependence of the inclusive inelastic electron scattering cross section (the EMC effect) has been measured for the first time in B10 and B11. Previous measurements of the EMC effect in A≤12 nuclei showed an unexpected nuclear dependence; B10 and B11 were measured to explore the EMC effect in this region in more detail. Results are presented for Be9, B10, B11, and C12 at an incident beam energy of 10.6 GeV. The EMC effect in the boron isotopes was found to be similar to that for Be9 and C12, yielding almost no nuclear dependence in the EMC effect in the range A=4–12. This represents important new data supporting the hypothesis that the EMC effect depends primarily on the local nuclear environment due to the cluster structure of these nuclei.Received 8 July 2022Revised 21 April 2023Accepted 17 July 2023DOI:https://doi.org/10.1103/PhysRevC.108.035201©2023 American Physical SocietyPhysics Subject Headings (PhySH)Research AreasLepton induced nuclear reactionsQCD in nuclear reactionsProperties6 ≤ A ≤ 19TechniquesParticle sources & targetsSpectrometers & spectroscopic techniquesNuclear Physics

Quasi-elastic scattering on $^{12}$C$(e,e'p)$ was measured in Hall C at Jefferson Lab for space-like 4-momentum transfer squared $Q^2$ in the range of 8--14.2\,(GeV/$c$)$^2$ with proton momenta up to 8.3\,GeV/$c$. The experiment was carried out in the upgraded Hall C at Jefferson Lab. It used the existing high momentum spectrometer and the new super high momentum spectrometer to detect the scattered electrons and protons in coincidence. The nuclear transparency was extracted as the ratio of the measured yield to the yield calculated in the plane wave impulse approximation. Additionally, the transparency of the $1s_{1/2}$ and $1p_{3/2}$ shell protons in $^{12}$C was extracted, and the asymmetry of the missing momentum distribution was examined for hints of the quantum chromodynamics prediction of Color Transparency. All of these results were found to be consistent with traditional nuclear physics and inconsistent with the onset of Color Transparency.

Quasielastic scattering on 12C(e, e'p) was measured in Hall C at Jefferson Lab for spacelike four-momentum transfer squared Q2 in the range of 8-14.2 (GeV/c)2 with proton momenta up to 8.3 GeV/c. The experiment was carried out in the upgraded Hall C at Jefferson Lab. It used the existing high-momentum spectrometer and the new super-high-momentum spectrometer to detect the scattered electrons and protons in coincidence. The nuclear transparency was extracted as the ratio of the measured yield to the yield calculated in the plane wave impulse approximation. Additionally, the transparency of the 1s1/2 and 1p3/2 shell protons in 12C was extracted, and the asymmetry of the missing momentum distribution was examined for hints of the quantum chromodynamics prediction of color transparency. All of these results were found to be consistent with traditional nuclear physics and inconsistent with the onset of color transparency.

The nuclear dependence of the inclusive inelastic electron scattering cross section (the EMC effect) has been measured for the first time in 10B and 11B. Previous measurements of the EMC effect in A 12 nuclei showed an unexpected nuclear dependence; 10B and 11B were measured to explore the EMC effect in this region in more detail. Results are presented for 9Be, 10B, 11B, and 12C at an incident beam energy of 10.6 GeV. The EMC effect in the boron isotopes was found to be similar to that for 9Be and 12C, yielding almost no nuclear dependence in the EMC effect in the range A = 4-12. This represents important new data supporting the hypothesis that the EMC effect depends primarily on the local nuclear environment due to the cluster structure of these nuclei.

The E12-14-012 experiment, performed in Jefferson Lab Hall A, has measured the $(e, e'p)$ cross section in parallel kinematics using a natural argon target. Here, we report the full results of the analysis of the data set corresponding to beam energy 2.222 GeV, and spanning the missing momentum and missing energy range $15 \lesssim p_m \lesssim 300$ MeV/c and $12 \lesssim E_m \lesssim 80$ MeV. The reduced cross section, determined as a function of $p_m$ and $E_m$ with $\approx$4\% accuracy, has been fitted using the results of Monte Carlo simulations involving a model spectral function and including the effects of final state interactions. The overall agreement between data and simulations turns out to be quite satisfactory ($\chi^2$/n.d.o.f.=1.9). The resulting spectral function will provide valuable new information, needed for the interpretation of neutrino interactions in liquid argon detectors.

Abstract Introduction Sequence variants in KCNJ2 are associated with Andersen-Tawil syndrome (ATS), a rare, multisystem disorder characterized by a triad of cardiac arrhythmia, periodic paralysis, and craniofacial-skeletal developmental anomalies. Purpose To define the cardiac and non-cardiac features of ATS associated with KCNJ2 variants. Methods Patients with KCNJ2 variants and features within the spectrum of ATS were identified from a detailed literature search between 2001 and 2020. Demographic, clinical and genetic data were collected. To avoid double counting the same proband, publications from the same authors or institutions were cross referenced and only included once unless it was evident that cases were not previously reported based on age, sex and specific KCNJ2. Minor allelic frequency was assessed in the Genome Aggregation Database (gnomAD). Results 296 patients (aged 25.5 ± 15.6 years) were identified from 66 publications. 136 (44%) were male and 162 (55%) probands. Age of symptom onset (reported in 100) was 10.7 ± 6.4 years. There were 162 probands. A family history of sudden death was reported for 23 probands. There were 69 different variants (fig 1a): missense (n=57), inframe deletion (n=5) and insertion (n=2), truncating (n=3), frameshift (n=1), copy number variant (n=1). Overall, penetrant disease was reported in 288 (96%), and only 2 (Arg312Cys, Pro415Leu) were seen in gnomAD. Variants at 2 residues (Arg67 and Arg218) were seen in 43 (26%) probands and 120 (41%) of all patients. Clinical data for all 3 major phenotypes was available for 289 individuals, with the full triad reported in 99 (34%) (fig 1b). A cardiac phenotype seen in 244 (84%), which was an isolated finding in 37 (13%). There was no difference in the phenotypic spectrum in those with variants Arg67 and Arg218 (fig 1c). An isolated cardiac phenotype was seen in 13/120 (11%) at these residues. Cardiac symptoms included palpitations (34/91; 37%), syncope (44/131; 34%). Cardiac arrest was reported in 20 (6.7%). ECG features included ventricular premature beats (VPB) (214/243; 90%), U wave (123/141; 87.2%), bidirectional (82/119; 68.9%), polymorphic (68/118; 57.6%) and monomorphic (7/35; 20.0%) ventricular tachycardia (VT). Arrhythmia-mediated cardiomyopathy was reported in 8. In 37 patients with an isolated cardiac phenotype, features included VPB (29/36; 81%), U waves (21/24; 88%), bidirectional (6/13; 43%), polymorphic (11/17; 65%) and monomorphic (2/7; 29%) VT. Cardiac arrest occurred in 5 (10%) cases. Conclusion The cardiac phenotype associated with KCNJ2 is highly varied. U-waves and VPB are prevalent features, and there is significant arrhythmic burden and morbidity. Identified KCNJ2 variants are highly penetrant and very rarely observed in the population. DIsease-associated variants are especially prevalent at the key functional residues 67 and 218. Improved recognition of this rare disorder will help further define the cardiac features and associated risk.

A mass spectroscopy experiment with a pair of nearly identical high-resolution spectrometers and a tritium target was performed in Hall A at Jefferson Lab. Utilizing the (e,e′K+) reaction, enhancements, which may correspond to a possible Λnn resonance and a pair of ΣNN states, were observed with an energy resolution of about 1.21 MeV (σ), although greater statistics are needed to make definitive identifications. An experimentally measured Λnn state may provide a unique constraint in determining the Λn interaction, for which no scattering data exist. In addition, although bound A=3 and 4 Σ hypernuclei have been predicted, only an A=4 Σ hypernucleus (HeΣ4) was found, utilizing the (K−,π−) reaction on a He4 target. The possible bound ΣNN state is likely a Σ0nn state, although this has to be confirmed by future experiments.Received 10 July 2020Revised 9 March 2022Accepted 9 May 2022DOI:https://doi.org/10.1103/PhysRevC.105.L051001©2022 American Physical SocietyPhysics Subject Headings (PhySH)Research AreasBinding energy & massesFew-body systemsMeson & hyperon induced nuclear reactionsNucleon-nucleon interactionsParticle interactionsPhysical SystemsHyperonsPropertiesA ≤ 5Nuclear PhysicsParticles & Fields

We performed an experiment using tritium and hydrogen cryogenic gas targets at Thomas Jefferson National Accelerator Facility (JLab) in 2018 (E12-17-003)[1, 2]. In this article, we discuss the Λ/Σ0 hyperon electroproduction from hydrogen target. Elementary Λ/Σ0 hyperon production processes are important not only for an absolute mass scale calibration in our experiment, but also for the study of the electroproduction mechanisms themselves. In this article, we reported the results of the differential cross section for the p(e, e’K+)Λ/Σ0 reaction at Q2 ∼ 0.5 (GeV/c)2.

When protons and neutrons (nucleons) are bound into atomic nuclei, they are close enough to feel significant attraction, or repulsion, from the strong, short-distance part of the nucleon-nucleon interaction. These strong interactions lead to hard collisions between nucleons, generating pairs of highly energetic nucleons referred to as short-range correlations (SRCs). SRCs are an important but relatively poorly understood part of nuclear structure1-3, and mapping out the strength and the isospin structure (neutron-proton (np) versus proton-proton (pp) pairs) of these virtual excitations is thus critical input for modelling a range of nuclear, particle and astrophysics measurements3-5. Two-nucleon knockout or 'triple coincidence' reactions have been used to measure the relative contribution of np-SRCs and pp-SRCs by knocking out a proton from the SRC and detecting its partner nucleon (proton or neutron). These measurements6-8 have shown that SRCs are almost exclusively np pairs, but they had limited statistics and required large model-dependent final-state interaction corrections. Here we report on measurements using inclusive scattering from the mirror nuclei hydrogen-3 and helium-3 to extract the np/pp ratio of SRCs in systems with a mass number of three. We obtain a measure of the np/pp SRC ratio that is an order of magnitude more precise than previous experiments, and find a marked deviation from the near-total np dominance observed in heavy nuclei. This result implies an unexpected structure in the high-momentum wavefunction for hydrogen-3 and helium-3. Understanding these results will improve our understanding of the short-range part of the nucleon-nucleon interaction.

A mass spectroscopy experiment with a pair of nearly identical high-resolution spectrometers and a tritium target was performed in Hall A at Jefferson Lab. Utilizing the (e, e' K+) reaction, enhancements, which may correspond to a possible Lambda nn resonance and a pair of Sigma NN states, were observed with an energy resolution of about 1.21 MeV (sigma), although greater statistics are needed to make definitive identifications. An experimentally measured Lambda nn state may provide a unique constraint in determining the Lambda n interaction, for which no scattering data exist. In addition, although bound A = 3 and 4 Sigma hypernuclei have been predicted, only an A = 4 Sigma hypernucleus (He-4(Sigma)) was found, utilizing the (K-, pi(-)) reaction on a He-4 target. The possible bound Sigma NN state is likely a Sigma(0)nn state, although this has to be confirmed by future experiments.

Missing-mass spectroscopy with the 3H(e, e′K+) reaction was carried out at Jefferson Lab’s (JLab) Hall A in Oct–Nov, 2018. The differential cross section for the 3H(γ∗, K+)Λnn was deduced at ω = Ee − Ee′ = 2.102 GeV and at the forward K+-scattering angle (0° ≤ θγ∗K ≤ 5°) in the laboratory frame. Given typical predicted energies and decay widths, which are (BΛ, Γ) = (−0.25, 0.8) and (−0.55, 4.7) MeV, the cross sections were found to be 11.2 ± 4.8(stat.)+4.1−2.1(sys.) and 18.1 ± 6.8(stat.)+4.2−2.9(sys.) nb/sr, respectively. The obtained result would impose a constraint for interaction models particularly between Λ and neutron by comparing to theoretical calculations.

Abstract. An nnΛ is a neutral baryon system with no charge. The study of the pure Λ-neutron system such as nnΛ gives us information on the Λn interaction. The nnΛ search experiment (E12-17-003) was performed at JLab Hall A in 2018. In this article, the Λn FSI was investigated by a shape analysis of the 3H(e, e′K+)X missing mass spectrum, and a preliminary result for the Λn FSI study is given.

The ratio of the nucleon F_{2} structure functions, F_{2}^{n}/F_{2}^{p}, is determined by the MARATHON experiment from measurements of deep inelastic scattering of electrons from ^{3}H and ^{3}He nuclei. The experiment was performed in the Hall A Facility of Jefferson Lab using two high-resolution spectrometers for electron detection, and a cryogenic target system which included a low-activity tritium cell. The data analysis used a novel technique exploiting the mirror symmetry of the two nuclei, which essentially eliminates many theoretical uncertainties in the extraction of the ratio. The results, which cover the Bjorken scaling variable range 0.19<x<0.83, represent a significant improvement compared to previous SLAC and Jefferson Lab measurements for the ratio. They are compared to recent theoretical calculations and empirical determinations of the F_{2}^{n}/F_{2}^{p} ratio.