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

N. Liyanage, B. D. Anderson, K. A. Aniol, L. Auerbach, F. T. Baker, J. Berthot, W. Bertozzi, P. -Y. Bertin, L. Bimbot, W. U. Boeglin, E. J. Brash, V. Breton, H. Breuer, E. Burtin, J. R. Calarco, L. Cardman, G. D. Cates, C. Cavata, C. C. Chang, J. -P. Chen, E. Cisbani, D. S. Dale, R. De Leo, A. Deur, B. Diederich, P. Djawotho, J. Domingo, B. Doyle, J. -E. Ducret, M. B. Epstein, L. A. Ewell, J. M. Finn, K. G. Fissum, H. Fonvieille, B. Frois, S. Frullani, J. Gao, F. Garibaldi, A. Gasparian, S. Gilad, R. Gilman, A. Glamazdin, C. Glashausser, J. Gomez, V. Gorbenko, T. Gorringe, F. W. Hersman, R. Holmes, M. Holtrop, N. d’Hose, C. Howell, G. M. Huber, C. E. Hyde-Wright, M. Iodice, C. W. de Jager, S. Jaminion, M. K. Jones, K. Joo, C. Jutier, W. Kahl, S. Kato, J. J. Kelly, S. Kerhoas, M. Khandaker, M. Khayat, K. Kino, W. Korsch, L. Kramer, K. S. Kumar, G. Kumbartzki, G. Laveissière, A. Leone, J. J. LeRose, L. Levchuk, M. Liang, R. A. Lindgren, G. J. Lolos, R. W. Lourie, R. Madey, K. Maeda, S. Malov, D. M. Manley, D. J. Margaziotis P. Markowitz, J. Martino, J. S. McCarthy, K. McCormick, J. McIntyre, R. L. J. van der Meer, Z. -E. Meziani, R. Michaels, J. Mougey, S. Nanda, D. Neyret, E. A. J. M. Offermann, Z. Papandreou, C. F. Perdrisat, R. Perrino, G. G. Petratos, S. Platchkov, R. Pomatsalyuk, D. L. Prout, V. A. Punjabi, T. Pussieux, G. Quéméner, R. D. Ransome, O. Ravel, Y. Roblin, R. Roche, D. Rowntree, G.A. Rutledge, P. M. Rutt, A. Saha, T. Saito, A. J. Sarty, A. Serdarevic-Offermann, T. P. Smith, A. Soldi, P. Sorokin, P. Souder, R. Suleiman, J. A. Templon, T. Terasawa, L. Todor, H. Tsubota, H. Ueno, P. E. Ulmer, G.M. Urciuoli, P. Vernin, S. van Verst, B. Vlahovic, H. Voskanyan, J. W. Watson, L. B. Weinstein, K. Wijesooriya, R. Wilson, B. Wojtsekhowski, D. G. Zainea, V. Zeps, J. Zhao, Z. -L. Zhou

The E12-14-012 experiment, performed in Jefferson Lab Hall A, has collected exclusive electron-scattering data (e,e$^\prime$p) in parallel kinematics using natural argon and natural titanium targets. Here, we report the first results of the analysis of the data set corresponding to beam energy of 2,222 MeV, electron scattering angle 21.5 deg, and proton emission angle -50 deg. The differential cross sections, measured with $\sim$4% uncertainty, have been studied as a function of missing energy and missing momentum, and compared to the results of Monte Carlo simulations, obtained from a model based on the Distorted Wave Impulse Approximation.

Differential cross sections of the exclusive process ep→e′π+n were measured with good precision in the range of the photon virtuality Q2=1.8–4.5 GeV2 and the invariant mass range of the π+n final state W=1.6–2.0 GeV using the Continuous Electron Beam Accelerator Facility Large Acceptance Spectrometer. Data were collected with nearly complete coverage in the azimuthal and polar angles of the nπ+ center-of-mass system. More than 37 000 cross-section points were measured. The contributions of the isospin I=12 resonances N(1675)52−,N(1680)52+, and N(1710)12+ were extracted at different values of Q2 using a single-channel, energy-dependent resonance amplitude analysis. Two different approaches, the unitary isobar model and the fixed-t dispersion relations, were employed in the analysis. We observe significant strength of the N(1675)52− in the A1/2 amplitude, which is in strong disagreement with quark models that predict both transverse amplitudes to be strongly suppressed. For the N(1680)52+ we observe a slow changeover from the dominance of the A3/2 amplitude at the real photon point (Q2=0) to a Q2 where A1/2 begins to dominate. The scalar amplitude S1/2 drops rapidly with Q2 consistent with quark model prediction. For the N(1710)12+ resonance our analysis shows significant strength for the A1/2 amplitude at Q2<2.5 GeV2.15 MoreReceived 8 December 2014DOI:https://doi.org/10.1103/PhysRevC.91.045203©2015 American Physical Society

The first high-statistics cross sections for the reactions $\gamma p \to K^{*+} \Lambda$ and $\gamma p \to K^{*+} \Sigma^0$ were measured using the CLAS detector at photon energies between threshold and 3.9 GeV at the Thomas Jefferson National Accelerator Facility. Differential cross sections are presented over the full range of the center-of-mass angles, $\theta^{CM}_{K^{*+}}$, and then fitted to Legendre polynomials to extract the total cross section. Results for the $K^{*+}\Lambda$ final state are compared with two different calculations in an isobar and a Regge model, respectively. Theoretical calculations significantly underestimate the $K^{*+} \Lambda$ total cross sections between 2.1 and 2.6 GeV, but are in better agreement with present data at higher photon energies.

The Electron Ion Collider (EIC) will be a next-generation facility for the study of the strong interaction (QCD). JLab’s MEIC is designed for high luminosities of up to 10^34 cm^-2 s^-1. This is achieved in part due to an aggressively small beta-star, which imposes stringent requirements on the collider rings’ dynamical properties. Additionally, one of the unique features of MEIC is a full-acceptance detector with a dedicated, small-angle, high-resolution detection system, capable of covering a wide range of momenta (and charge-to-mass ratios) with respect to the original ion beam to enable access to new physics. The detector design relies on a number of features, such as a 50 mrad beam crossing angle, large-aperture ion and electron final focusing quads and spectrometer dipoles as well as a large machine-element-free detection space downstream of the final focusing quads. We present an interaction region design developed with close integration of the detector and beam dynamical aspects. The dynamical aspect of the design rests on a symmetry-based concept for compensation of non-linear effects. The optics and geometry have been optimized to accommodate the detection requirements and to ensure the interaction region’s modularity for easiness of integration into the collider ring lattices. As a result, more » the design offers an excellent detector performance combined with the necessary non-linear dynamical properties. « less

K. Park, 2, ∗ V.D. Burkert, W. Kim, I.G. Aznauryan, 2 R. Minehart, L.C. Smith, K. Joo, 41 L. Elouadrhiri, 2 G. Adams, M.J. Amaryan, P. Ambrozewicz, M. Anghinolfi, G. Asryan, H. Avakian, 2 H. Bagdasaryan, 32 N. Baillie, J.P. Ball, N.A. Baltzell, S. Barrow, V. Batourine, M. Battaglieri, I. Bedlinskiy, M. Bektasoglu, M. Bellis, N. Benmouna, B.L. Berman, A.S. Biselli, 7, 15 L. Blaszczyk, B.E. Bonner, C. Bookwalter, S. Bouchigny, S. Boiarinov, 2 R. Bradford, D. Branford, W.J. Briscoe, W.K. Brooks, S. Bültmann, C. Butuceanu, J.R. Calarco, S.L. Careccia, D.S. Carman, 2 L. Casey, A. Cazes, S. Chen, L. Cheng, P.L. Cole, 8, 20 P. Collins, P. Coltharp, D. Cords, P. Corvisiero, D. Crabb, V. Crede, J.P. Cummings, D. Dale, N. Dashyan, R. De Masi, 23 R. De Vita, E. De Sanctis, P.V. Degtyarenko, H. Denizli, L. Dennis, A. Deur, S. Dhamija, K.V. Dharmawardane, K.S. Dhuga, R. Dickson, C. Djalali, G.E. Dodge, J. Donnelly, D. Doughty, 2 M. Dugger, S. Dytman, O.P. Dzyubak, H. Egiyan, 2, † K.S. Egiyan, L. El Fassi, P. Eugenio, 17 R. Fatemi, G. Fedotov, G. Feldman, R.J. Feuerbach, T.A. Forest, 20 A. Fradi, H. Funsten, M.Y. Gabrielyan, M. Garçon, G. Gavalian, 32 N. Gevorgyan, G.P. Gilfoyle, K.L. Giovanetti, F.X. Girod, 2 J.T. Goetz, W. Gohn, E. Golovatch, ‡ A. Gonenc, C.I.O. Gordon, R.W. Gothe, L. Graham, K.A. Griffioen, M. Guidal, M. Guillo, N. Guler, L. Guo, V. Gyurjyan, C. Hadjidakis, K. Hafidi, K. Hafnaoui, H. Hakobyan, R.S. Hakobyan, C. Hanretty, J. Hardie, 2 N. Hassall, § D. Heddle, F.W. Hersman, K. Hicks, I. Hleiqawi, M. Holtrop, C.E. Hyde-Wright, Y. Ilieva, D.G. Ireland, B.S. Ishkhanov, E.L. Isupov, M.M. Ito, D. Jenkins, H.S. Jo, J.R. Johnstone, H.G. Juengst, 32 N. Kalantarians, D. Keller, J.D. Kellie, M. Khandaker, K.Y. Kim, A. Klein, F.J. Klein, 8 A.V. Klimenko, M. Klusman, M. Kossov, Z. Krahn, L.H. Kramer, 2 V. Kubarovsky, J. Kuhn, 7 S.E. Kuhn, S.V. Kuleshov, V. Kuznetsov, J. Lachniet, 32 J.M. Laget, 2 J. Langheinrich, D. Lawrence, T. Lee, Ji Li, A.C.S. Lima, K. Livingston, H.Y. Lu, K. Lukashin, M. MacCormick, N. Markov, P. Mattione, S. McAleer, B. McKinnon, J.W.C. McNabb, B.A. Mecking, S. Mehrabyan, J.J. Melone, M.D. Mestayer, C.A. Meyer, T. Mibe, K. Mikhailov, M. Mirazita, R. Miskimen, V. Mokeev, 2 L. Morand, B. Moreno, K. Moriya, S.A. Morrow, 9 M. Moteabbed, J. Mueller, E. Munevar, G.S. Mutchler, P. Nadel-Turonski, R. Nasseripour, 37 S. Niccolai, 23 G. Niculescu, 25 I. Niculescu, 2, 25 B.B. Niczyporuk, M.R. Niroula, R.A. Niyazov, 2 M. Nozar, ¶ G.V. O’Rielly, M. Osipenko, 28 A.I. Ostrovidov, S. Park, E. Pasyuk, C. Paterson, S. Anefalos Pereira, S.A. Philips, J. Pierce, N. Pivnyuk, D. Pocanic, O. Pogorelko, E. Polli, I. Popa, S. Pozdniakov, B.M. Preedom, J.W. Price, Y. Prok, 2, ∗∗ D. Protopopescu, 19 L.M. Qin, B.A. Raue, 2 G. Riccardi, G. Ricco, M. Ripani, B.G. Ritchie, F. Ronchetti, G. Rosner, P. Rossi, D. Rowntree, P.D. Rubin, F. Sabatié, 9 M.S. Saini, J. Salamanca, C. Salgado, J.P. Santoro, 8, 2 V. Sapunenko, 2 D. Schott, R.A. Schumacher, V.S. Serov, Y.G. Sharabian, D. Sharov, J. Shaw, N.V. Shvedunov, A.V. Skabelin, E.S. Smith, D.I. Sober, D. Sokhan, A. Stavinsky, S.S. Stepanyan, S. Stepanyan, B.E. Stokes, P. Stoler, I.I. Strakovsky, S. Strauch, 37 R. Suleiman, M. Taiuti, T. Takeuchi, D.J. Tedeschi, 14 A. Tkabladze, 18 S. Tkachenko, L. Todor, 36 C. Tur, M. Ungaro, 11 M.F. Vineyard, 36 A.V. Vlassov, D.P. Watts, †† L.B. Weinstein, D.P. Weygand, M. Williams, E. Wolin, M.H. Wood, ‡‡ A. Yegneswaran, J. Yun, M. Yurov, L. Zana, B. Zhang, J. Zhang, B. Zhao, and Z.W. Zhao

We report observation of a narrow peak structure at $\ensuremath{\sim}$1.54 GeV with a Gaussian width $\ensuremath{\sigma}=6$ MeV in the missing mass of ${K}_{S}$ in the reaction $\ensuremath{\gamma}+p\ensuremath{\rightarrow}p{K}_{S}{K}_{L}$. The observed structure may be due to the interference between a strange (or antistrange) baryon resonance in the $p{K}_{L}$ system and the $\ensuremath{\varphi}({K}_{S}{K}_{L})$ photoproduction leading to the same final state. The statistical significance of the observed excess of events estimated as the log-likelihood ratio of the resonant signal + background hypothesis and the $\ensuremath{\varphi}$-production-based background-only hypothesis corresponds to $5.3\ensuremath{\sigma}$.

Measuring nucleon-nucleon short range correlations (SRCs) has been a goal of the nuclear physics community for many years. They are an important part of the nuclear wave function, accounting for almost all of the high-momentum strength. They are closely related to the EMC effect. While their overall probability has been measured, measuring their momentum distributions is more difficult. In order to determine the best configuration for studying SRC momentum distributions, we measured the ${}^{3}$He$(e,\phantom{\rule{-0.16em}{0ex}}{e}^{\ensuremath{'}}pp)n$ reaction, looking at events with high-momentum protons (${p}_{p}>0.35$ GeV/c) and a low-momentum neutron (${p}_{n}<0.2$ GeV/c). We examined two angular configurations: either both protons emitted forward or one proton emitted forward and one backward (with respect to the momentum transfer, $\stackrel{P\vec}{q}$). The measured relative momentum distribution of the events with one forward and one backward proton was much closer to the calculated initial-state $pp$ relative momentum distribution, indicating that this is the preferred configuration for measuring SRC.

The Jefferson Lab's Medium-energy Electron Ion Collider (MEIC) is proposed as a next-generation facility for the study of strong interaction (QCD). Accessing the relevant physics requires a full-acceptance detector with a dedicated small-angle high-resolution detection system capable of covering a wide range of momenta (and charge-to-mass ratios) with respect to the original ion beam. We present a design of such a detection system integrated into the collider's interaction region, in which full acceptance is attained by letting small-angle collision products pass through the nearest elements of the machine final-focusing system for further detection. The proposed design is consistent with the current collider optics and demonstrates an excellent performance in terms of detector acceptance and resolution.

A lead–glass hodoscope calorimeter that was constructed for use in the Jefferson Lab Real Compton Scattering experiment is described. The detector provides a measurement of the coordinates and the energy of scattered photons in the GeV energy range with resolutions of 5mm and 6%/EγGeV. Features of both the detector design and its performance in the high luminosity environment during the experiment are presented.

We measured with unprecedented precision the induced polarization P-y in He-4(e, e(l)(p) over right arrow)H-3 at Q(2) = 0.8 and 1.3 (GeV/c)(2). The induced polarization is indicative of reaction-mechanism effects beyond the impulse approximation. Our results are in agreement with a relativistic distorted-wave impulse approximation calculation but are overestimated by a calculation with strong charge-exchange effects. Our data are used to constrain the strength of the spin-independent charge-exchange term in the latter calculation.

We measured with unprecedented precision the induced polarization P(y) in (4)He(e,e'p)(3)H at Q(2)=0.8 and 1.3  (GeV/c)(2). The induced polarization is indicative of reaction-mechanism effects beyond the impulse approximation. Our results are in agreement with a relativistic distorted-wave impulse approximation calculation but are overestimated by a calculation with strong charge-exchange effects. Our data are used to constrain the strength of the spin-independent charge-exchange term in the latter calculation.