Bulletin of the American Physical Society
5th Joint Meeting of the APS Division of Nuclear Physics and the Physical Society of Japan
Volume 63, Number 12
Tuesday–Saturday, October 23–27, 2018; Waikoloa, Hawaii
Session DE: Mini-symposium on Strangeness Nuclear Physics Today and Tomorrow II |
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Chair: Hirokazu Tamura, Tohoku University Room: Hilton King's 1 |
Thursday, October 25, 2018 9:00AM - 9:15AM |
DE.00001: Search for the Lambda-nn state using electron scattering Toshiyuki Gogami A bound state of two neutrons and a Lambda has been indicated to exist by a heavy ion beam experiment at GSI. However, the baryon interactions which have been investigated through scattering experiments and (hyper)nuclear spectroscopy cannot explain any bound states in the three-body isotriplet system with a Lambda. On the other hand, the Lambda-nn is predicted to exist as a resonant state in some theoretical calculations. A missing mass experiment using electron scattering has sensitivity to measure either state (bound or resonant states). In contrast to conventional reaction spectroscopy with hadron beams, more accurate and precise measurements on Lambda binding energies which are required to pin down the existence of Lambda-nn have been realized by recent reaction spectroscopy with the (e,e’K+) reaction at Jefferson Lab, U.S. Moreover, the measured energy and width would provide us interaction information between a Lambda and neutron for which no scattering data exist. The Lambda-nn search experiment will be carried out with a tritium target via the (e,e’K+) reaction at JLab Hall A on October—November, 2018. I will present an overview and status of the experiment. |
Thursday, October 25, 2018 9:15AM - 9:30AM |
DE.00002: Status of Λn interaction study via the final state interaction effect in γ+d->K++Λ+n production Masashi Kaneta The study of Baryon interaction including strangeness have been mainly carried by Hypernuclear experiment, because of difficulties of the Hyperon-Nucleon (YN) scattering. The recent results of 4ΛH and 4ΛHe measurements show existing of a charge symmetry breaking (CSB) in ΛN interaction. It is suggested that the ΛN CSB is due to ΛΣ coupling in ΛN. On the other hand, there is lack of precise data in the Λn interaction. The measurement of Λn interaction is one of the key issues in the strangeness nuclear physics. The Λn interaction can be extracted by comparing cross-sections of γ+d->K++Λ+n and γ+p->K++Λ due to final state effect of Λn. We have been investigating strangeness photoproduction with tagged photon beam in Research Center for Electron Photon Science (ELPH), Tohoku University. The spectrometer, NKS2, was originally designed for K0 Λ production. Upgrades of NKS2 detectors for the Λn FSI experiment are in progress: high resolution TOF counter by Multi-gap Resistive Plate Chamber and Electron Veto by Aerogel Cherenkov counter. We will present the plan of experiment with beam time estimation and requirements/achievement of detector performance.
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Thursday, October 25, 2018 9:30AM - 9:45AM |
DE.00003: Analysis Status of Σ-p Scattering Experiment at J-PARC Yoshiyuki Nakada Systematic knowledge in the interaction between baryons including the strangeness sector is still limited. Therefore study of ΣN interaction from scattering experiment data is needed to draw clear picture of the ΣN interaction. We proposed Σp scattering experiment (J-PARC E40) to study ΣN interaction with a high statistics J-PARC E40 is an experiment to measure differential cross sections of both of Σ+p and Σ-p elastic scatterings and also Σ-p -> Λn inelastic scattering in the momentum range of 400--700 MeV/c. The experiment is performed in the K1.8 beam line at the J-PARC hadron hall. Σ production event in πp -> ΣK reaction in a liquid hydrogen target is detected with the KURAMA spectrometer, and following Σp scattering event is detected with the scattering proton detector (CATCH). In this February and June of 2018, the detector commissioning has been performed. We took calibration data and a part of Σ- production data. In this talk, we would like to report the analysis status. |
Thursday, October 25, 2018 9:45AM - 10:00AM |
DE.00004: The analysis for Σ- yield in Σ p scattering experiment (J-PARC E40) Norina Fujioka, Koji Miwa, Ryotaro Honda, Suharu Hoshino, Shuhei Hayakawa, Yoshiyuki Nakada Understanding of S N (I = 3/2, S = 1) interaction is a key to reveal the origin of the short range core in the baryon – baryon interactions because a large repulsive force is predicted to originate from Pauli effect in the quark level and S N interactions are also not understood well. Therefore the systematic study of S N channel is very important. In order to investigate these topics, we have planed a S p scattering experiment (J-PARC E40) and will measure the differential cross sections of Σ+ p and Σ- p elastic scatterings and Σ- p -> Λ n inelastic scattering. In this experiment, we detect successive sets of two-body reactions in a liquid hydrogen target; p p -> S K+ by the spectrometers up/downstream from the target, and S p -> S p scattering event by the scattered proton detector surrounding the target (CATCH). We started a Σ- p scattering experiment at first and took a part of the Σ- production data in June 2018 and we will report the analysis for Σ- yield. |
Thursday, October 25, 2018 10:00AM - 10:15AM |
DE.00005: DAQ upgrade for the use of the high intensity π beam in the Σp scattering experiment (J-PARC E40) Ryotaro Honda The short range repulsion of the baryon-baryon interaction is phenomenally known but its origin is not conclusive. One possible source is the Pauli blocking in the quark level and the quite strong repulsion in the Σ+p (S=1, I=3/2) channel is expected. Thus, we planed to perform a high statistics Σp scattering experiment to investigate the origin of the repulsive core through the Σ+p scattering and to reveal the nature of the ΣN interaction through the Σ- p scatterings. In order to perform this experiment within the reasonable beam time, the use of the high intensity π beam up to 10 MHz is the key. However, as the increase of the beam intensity makes the trigger rate high, the significant data loss is expected with the present DAQ system. Thus, we upgraded our DAQ system. One upgraded point is to shorten the hardware busy time by replacing several electronics and by improving the readout method. The next one is to introduce the specified trigger system to reduce the trigger rate. |
Thursday, October 25, 2018 10:15AM - 10:30AM |
DE.00006: Preparation status of the hypernuclear gamma-ray spectroscopy for Λ's g-factor in a nucleus (J-PARC E63) Honoka Kanauchi, Yuji Ishikawa, Mifuyu Ukai, Takeshi Koike, Hirokazu Tamura, Ryotaro Honda, Manami Fujita, Takeshi Yamamoto Properties of baryons in nuclear matter may be changed from those in free space because of its high density. However, nucleons deep inside a nucleus cannot be probed due to very short life time of the highly excited states. On the other hand, hyperons are free from Pauli effect from nucleons in a nucleus. Thus, hyperons can be a good probe to investigate possible modification of baryons in a nucleus. We plan to study modification of a Λ particle in a nucleus by measuring that of the magnetic moment. Λ's magnetic moment can be derived from the lifetime of spin flip M1 transition. Therefore we proposed a γ ray spectroscopy of hypernuclei (J-PARC E63) at the K1.1 beam line in J-PARC. We will measure the γ ray of spin flip M1 transition by Ge detectors array (Hyperball-J) to obtain the lifetime using Doppler Shift Attenuation Method (DSAM). DSAM is a method to obtain the lifetime from γ ray peak shape which is determined by lifetime and stopping time of hypernuclei in a nucleus. For this purpose, a lithium oxide target, which has uniform density, is very important. Now we are challenging to produce the crystal of lithium oxide. In this presentation, we will introduce about the J-PARC E63 experiment and report the preparation status. |
Thursday, October 25, 2018 10:30AM - 10:45AM |
DE.00007: Result of 12C(K-, p) analysis of the J-PARC E05 pilot run Yudai Ichikawa We have measured an inclusive missing-mass spectrum without any trigger biases of the 12C(K-, p) reaction at the kaon incident momentum of 1.8 GeV/c. This data was taken as a by-product of the J-PARC E05 pilot run, which aim to search for the Xi-hypernuclei. We have obtained the spectrum in high statistics and high energy resolution of 4.2 MeV (sigma) in a wide energy region of BK = -700 to 300 MeV. The spectrum was compared with a DWIA calculation based on the Morimatsu-Yazaki Green's function method, in which the complex Kbar-nucleus potential U = V + iW is an input parameter. The spectrum in the quasi-free Kbar-n scattering region and Kbar bound region were fitted with these calculations. The observed spectrum around the quasi-elastic and shallow binding energy region is well reproduced by the calculation of the potential depth of V ~ -80 MeV and W ~ -40 MeV. Here, we have observed the definitive excess in large binding energy region BK > 100 MeV. Namely, we can not find a potential parameter set which reproduces this excess. We may need to consider energy-dependent potentials including multi-nucleon absorption processes. A possible interpretation of this excess is the existence of the bound state between Lambda(1405) and 10Be system. |
Thursday, October 25, 2018 10:45AM - 11:00AM |
DE.00008: Model-independent study on the structure of Lambda(1405) Yuki Kamiya, Tetsuo Hyodo Understanding of the internal structure of exotic hadrons is an important topic of the current hadron physics. Particularly in recent years, precise data on the hadron scattering have been accumulated from the experimental analysis, and it is becoming possible to extract detailed information on the scattering amplitude. This enables us to study the hadron structure from the properties of the scattering amplitude. In this talk, we show that the internal structure of hadron resonances is related to the pole position, the scattering length, and the zero of the scattering amplitude. By using the recent analysis of the Lambda(1405) in the meson-baryon scattering, we show that the dominance of the KbarN composite component of the high-mass pole of Lambda(1405) is concluded only with the experimental observables. Furthermore, we also discuss the method to determine the KbarN amplitude from experimental data analysis in a model-independent manner. |
Thursday, October 25, 2018 11:00AM - 11:15AM |
DE.00009: On mass polarization and exchange effects in nuclear three-body systems Roman Ya Kezerashvili, Igor Filikhine, Branislav Vlahovic Using the method of Faddeev equations in configuration space the mass polarization effect is considered for three-body systems with two identical particles: AAB. We present three-body calculations for the 3H nucleus, the double-Λ(Ξ) hypernuclei, and kaonic clusters pK-K- and ppK-. We show that competition between the mass polarization contribution to the kinetic energy and the term related to the exchange of identical particles leads to two opposite relations between B3(VAA=0) and 2B2, where B3(VAA=0) is the three-body energy of a system, when the interaction between identical particles is omitted, 2B2 is the binding energy of AB subsystem. The mass ratio mA/mB affects the mass polarization contribution and AB potential strength affects the exchange term directly. The latter also depends on the Clebsch–Gordan coefficients of spin/isospin state of the system. For bosonic-like systems B3(VAA=0)>2B2, for systems complicated by spin/isospin dependence, the relation B3(VAA=0)<2B2 is satisfied for the wide range of mass ratio. The last relation allows us to estimate the quasi-bound state energy of three-body kaonic clusters. The effect of variation of AB potential strength for hypernuclear and kaonic systems is studied. |
Thursday, October 25, 2018 11:15AM - 11:30AM |
DE.00010: Σc(*)N dibaryon resonances in the phenomenological potential model Makoto Oka, Saori Maeda, Yan-rui Liu Two-body Jπ = 0+,1+, and 2+ resonance states of the Yc (=Λc, Σc, or Σ*c) and N systems are analyzed by the use of the complex scaling method. We employ the YcN phenomenological potentials, which are composed of the long-range meson-exchange force and the short-range quark exchange force. We find four Feshbach-type resonance states slightly below the ΣcN, or Σ*cN threshold. It is found that the four resonances form two pairs of the heavy-quark doublets in agreement with the heavy quark spin symmetry. |
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