-
T Suzuki,
H Bhang,
J Chiba,
S Choi,
Y Fukuda, T Hanaki,
R S Hayano,
M Iio,
T Ishikawa,
S Ishimoto, [......],
Y Matsuda,
H Ohnishi,
S Okada,
H Outa,
M Sato,
S Suzuki,
D Tomono,
E Widmann,
T Yamazaki,
H Yim
[show abstract]
[hide abstract]
ABSTRACT: Correlations of back-to-back coincident Λd and Λt pairs from the stopped K − reaction on 4 He had been investigated, thereby Λd and Λt branches of non-mesonic three-and four-nucleon absorption processes of antikaon at rest were identified as well-separable processes, respectively. The branching ratio of the three-nucleon process, (4 He-K −) atomic → Λd"n", is estimated to be (0.9 ± 0.1(stat) ± 0.2(syst)) × 10 −3 from the normalized Λd spectrum in a Λdn final state, while the fraction of the four-nucleon process, (4 He-K −) atomic → Λt, is obtained to be (3.1 ± 0.4(stat) ± 0.5(syst)) × 10 −4 per stopped K − .
10/2010;
-
T Suzuki,
H. Bhang,
J Chiba,
S Choi,
Y Fukuda, T. Hanaki,
R S Hayano,
M Iio,
T Ishikawa,
S Ishimoto, [......],
Y Matsuda,
H Ohnishi,
S Okada,
H. Outa,
M Sato,
S Suzuki,
D. Tomono,
E. Widmann,
T Yamazaki,
H Yim
[show abstract]
[hide abstract]
ABSTRACT: We have investigated correlations of coincident $\Lambda N$ pairs from the stopped $K^-$ reaction on ${}^4$He, and clearly observed $\Lambda p$ and $\Lambda n$ branches of the two-nucleon absorption process in the $\Lambda N$ invariant mass spectra. In addition, non-mesonic reaction channels, which indicate possible exotic signals for the formation of strange multibaryon states, have been identified.
12/2007;
-
T. Suzuki,
H. Bhang,
J. Chiba,
S. Choi,
Y. Fukuda, T. Hanaki,
R. S. Hayano,
M. Iio,
T. Ishikawa,
S. Ishimoto, [......],
Y. Matsuda,
H. Ohnishi,
S. Okada,
H. Outa,
M. Sato,
S. Suzuki,
D. Tomono,
E. Widmann,
T. Yamazaki,
H. Yim
[show abstract]
[hide abstract]
ABSTRACT: We have observed an intense high-energy component in an inclusive 4He(stopped K-,d) spectrum. For back-to-back Λd pairs a prominent event cluster has been found just below the m4He+mK--mn mass threshold in the Λd invariant mass spectrum of Λdn events, which is evidence for a three-nucleon absorption process of K- in 4He. In addition, an appreciable strength is revealed below ~3220 MeV/c2. Well separated Σ0dn events show a peak similar to the case of Λdn.
Phys. Rev. C. 12/2007; 76(6).
-
T Suzuki,
H. Bhang,
J Chiba,
S Choi,
Y Fukuda, T. Hanaki,
R S Hayano,
M Iio,
T Ishikawa,
S Ishimoto, [......],
Y Matsuda,
H Ohnishi,
S Okada,
H. Outa,
M Sato,
S Suzuki,
D. Tomono,
E. Widmann,
T Yamazaki,
H Yim
[show abstract]
[hide abstract]
ABSTRACT: We have observed an intense high-energy component in an inclusive $^4$He(stopped $K^-$, $d$) spectrum. For back-to-back $\Lambda d$ pairs a prominent event cluster has been found just below the $m_{^4\textrm{He}}+m_{K^-}-m_{n}$ mass threshold in the $\Lambda d$ invariant mass spectrum of $\Lambda dn$ events, which is evidence for a three-nucleon absorption process of $K^-$ in $^4$He. In addition, an appreciable strength is revealed below $\sim$3220 MeV/$c^2$. Well separated $\Sigma^0 dn$ events show a peak similar to the case of $\Lambda dn$.
10/2007;
-
M Sato,
H. Bhang,
J Chiba,
Seonho Choi,
Y Fukuda, T. Hanaki,
R S Hayano,
M Iio,
T Ishikawa,
S Ishimoto, [......],
Y Matsuda,
H Ohnishi,
S Okada,
H. Outa,
S Suzuki,
T Suzuki,
D. Tomono,
E. Widmann,
T Yamazaki,
H Yim
[show abstract]
[hide abstract]
ABSTRACT: A search for tribaryon states was performed at KEK-PS. We adopted the $^4$He($K^-_{stopped}, p)$ reaction to populate the states with strangeness -1, charge 0 and isospin 1. No significant narrow structure was observed in the mass region from 3000 to 3200 MeV/c^2 in an inclusive missing mass spectrum. The upper limit of the formation branching ratio was determined to be ($1\sim3)\times 10^{-4}$, ($0.7\sim2)\times 10^{-3}$ and ($2\sim8) \times 10^{-3}$/($stopped K^{-}$) with 95 % confidence level for narrow states with an assumed width of 0, 20 and 40 MeV/c^2, respectively.
09/2007;
-
S Okada,
G Beer,
H. Bhang,
M. Cargnelli,
J Chiba,
Seonho Choi,
C. Curceanu,
Y Fukuda, T. Hanaki,
R S Hayano, [......],
M Sato,
P Schmid,
S Suzuki,
T Suzuki,
H. Tatsuno,
D. Tomono,
E. Widmann,
T Yamazaki,
H Yim,
J. Zmeskal
[show abstract]
[hide abstract]
ABSTRACT: We have measured the Balmer-series x-rays of kaonic $^4$He atoms using novel large-area silicon drift x-ray detectors in order to study the low-energy $\bar{K}$-nucleus strong interaction. The energy of the $3d \to 2p$ transition was determined to be 6467 $\pm$ 3 (stat) $\pm$ 2 (syst) eV. The resulting strong-interaction energy-level shift is in agreement with theoretical calculations, thus eliminating a long-standing discrepancy between theory and experiment.
Physics Letters B 08/2007; 653:387-391. · 3.95 Impact Factor
-
M Iwasaki,
H. Bhang,
J Chiba,
S Choi,
Y Fukuda, T. Hanaki,
R S Hayano,
M Iio,
T Ishikawa,
S Ishimoto, [......],
H Ohnishi,
S Okada,
H. Outa,
M Sato,
S Suzuki,
T Suzuki,
D. Tomono,
E. Widmann,
T Yamazaki,
H Yim
[show abstract]
[hide abstract]
ABSTRACT: Very recently, we have performed a couple of experiments, {\it{KEK PS-E549/E570}}, for the detailed study of the strange tribaryon $S^0(3115)$ obtained in {\it{KEK PS-E471}}. These experiments were performed to accumulate much higher statistics with improved experimental apparatusespecially for the better proton spectroscopy of the $^4$He({\it{stopped K}}$^-$, {\it{N}}) reaction. In contrast to the previous proton spectrum, no narrow ($\sim$ 20 MeV) peak structure was found either in the inclusive $^4$He({\it{stopped K}}$^-$, {\it{p}}) or in the semi-inclusive $^4$He({\it{stopped K}}$^-$, {\it{p}}$X^\pm$) reaction channel, which is equivalent to the previous $E471$ event trigger condition. Detailed analysis of the present data and simulation shows that the peak, corresponding to $S^0(3115)$, has been an experimental artifact. Present analysis does not exclude the possible existence of a much wider structure. To be sensitive to such structure and for better understanding of the non-mesonic $K^-$ absorption reaction channel, detailed analysis of the data is in progress.
07/2007;
-
H. Yim,
H. Bhang,
J. Chiba,
S. Choi,
Y. Fukuda, T. Hanaki,
R. S. Hayano,
M. Iio,
T. Ishikawa,
S. Ishimoto, [......],
Y. Matsuda,
H. Ohnishi,
S. Okada,
H. Outa,
M. Sato,
S. Suzuki,
T. Suzuki,
D. Tomono,
E. Widmann,
T. Yamazaki
[show abstract]
[hide abstract]
ABSTRACT: Recent prediction of Akaishi and Yamazaki on the strongly bound kaonic nuclear states with remarkably narrow widths have generated
a lot of physics interests and the states have been studied and discussed intensively [1]. The fundamental motivation behind such intense study was that on one hand they could give us the excellent opportunities
to investigate dense and cold hadronic systems in which quarks may be deconfined and the partial restoration of the chiral
symmetry is expected to occur in a large scale [2], on the other hand the existence itself with such narrow width is extremely peculiar and interesting. Since then, the states
have been studied in a series of experiments at BNL [3], KEK [4,5], GSI [6] and LNF [7]. We have recently reported an indication of a strange tribaryon state, S+, with a width Γ < 23 MeV/c
2, in the neutron time of flight (TOF) spectrum of the 4He(K
stop
−
, n) reaction in the KEK-PS E471 which was the first experiment at KEK-PS to search for the deeply bound narrow K
−
ppn (T=0) state [4]. In order to confirm the state, S+, and search for other possible total isospin T=0/1 tribaryonic states, we have re-measured the neutron energy spectrum from
4He(K
stop
−
, n) reaction in the KEK-PS E549 experiment with the upgraded setup with which TOF resolution was improved 1.5 times and the
statistics was increased 6 times. However, in the neutron spectra, we find such a smooth momentum distribution that we conclude
the state either not so strong to stick out of the inclusive background or too broad to form a peak. It is now necessary to
analyze the data for further details such as the hyperon motion correlation.
12/2006: pages 201-205;
-
R. S. Hayano,
G. Beer,
H. Bhang,
M. Cargnelli,
J. Chiba,
S. Choi,
C. Curceanu,
Y. Fukuda, T. Hanaki,
M. Iio, [......],
M. Sato,
P. Schmid,
S. Suzuki,
T. Suzuki,
H. Tatsuno,
D. Tomono,
E. Widmann,
T. Yamazaki,
H. Yim,
J. Zmeskal
[show abstract]
[hide abstract]
ABSTRACT: The Balmer-series X-rays of kaonic helium-4 have been re-measured with a projected goal of determining the 2p-level strong-interaction shift to a precision better than a few electron volts. Preliminary results indicate that the shift
must be much smaller than the current world average of −43 ± 8 eV.
12/2006: pages 183-187;
-
S. Okada,
G. Beer,
H. Bhang,
M. Cargnelli,
J. Chiba,
S. Choi,
C. Curceanu,
Y. Fukuda, T. Hanaki,
R. S. Hayano, [......],
M. Sato,
P. Schmid,
S. Suzuki,
T. Suzuki,
H. Tatsuno,
D. Tomono,
E. Widmann,
T. Yamazaki,
H. Yim,
J. Zmeskal
[show abstract]
[hide abstract]
ABSTRACT: We have performed an experiment to measure the strong‐interaction shift of 2p states of kaonic helium‐4 atom with a precision better than ∼2 eV. The measurement will give an answer to the longstanding “kaonic helium puzzle” and provide crucial information to understand the basis of the Akaishi‐Yamazaki prediction of deeply‐bound kaonic nuclei, which is one of the interpretations of the strange multibaryon candidates recently reported at KEK, DAΦNE and BNL. © 2006 American Institute of Physics
AIP Conference Proceedings. 11/2006; 870(1):493-495.
-
M. Iwasaki,
H. Bhang,
J. Chiba,
S. Choi,
Y. Fukuda, T. Hanaki,
R.S. Hayano,
M. Iio,
T. Ishikawa,
S. Ishimoto, [......],
H. Ohnishi,
S. Okada,
H. Outa,
M. Sato,
S. Suzuki,
T. Suzuki,
D. Tomono,
E. Widmann,
T. Yamazaki,
H. Yim
[show abstract]
[hide abstract]
ABSTRACT: Very recently, we have performed a couple of experiments, KEK PS-E549/E570, for the detailed study of the strange tribaryon S0(3115) obtained in KEK PS-E471. In contrast to the previous proton spectrum, no narrow (∼20 MeV) peak structure was found either in the inclusive 4He(stoppedK−, p) or in the semi-inclusive 4He(stoppedK−, pX±) reaction channel, which is equivalent to the previous E471 event trigger condition. Detailed analysis of the present data and simulation shows that the peak, corresponding to S0(3115), has been an experimental artifact. Present analysis does not exclude the possible existence of a much wider structure.
Nuclear Physics A.
-
M. Sato,
H. Bhang,
J. Chiba,
Seonho Choi,
Y. Fukuda, T. Hanaki,
R.S. Hayano,
M. Iio,
T. Ishikawa,
S. Ishimoto, [......],
Y. Matsuda,
H. Ohnishi,
S. Okada,
H. Outa,
S. Suzuki,
T. Suzuki,
D. Tomono,
E. Widmann,
T. Yamazaki,
H. Yim
[show abstract]
[hide abstract]
ABSTRACT: A search for tribaryon states was performed at KEK-PS. We adopted the 4He() reaction to populate the states with strangeness −1, charge 0 and isospin 1. No significant narrow structure was observed in the mass region from 3000 to 3200 MeV/c2 in an inclusive missing mass spectrum. The upper limit of the formation branching ratio was determined to be (0.4–6)×10−4, (0.2–6)×10−3 and (0.06–5)×10−2/(stopped K−) with 95% confidence level for a narrow state with an assumed width of 0, 20 and 40 MeV/c2, respectively.
Physics Letters B.
-
S. Okada,
G. Beer,
H. Bhang,
M. Cargnelli,
J. Chiba,
Seonho Choi,
C. Curceanu,
Y. Fukuda, T. Hanaki,
R.S. Hayano, [......],
M. Sato,
P. Schmid,
S. Suzuki,
T. Suzuki,
H. Tatsuno,
D. Tomono,
E. Widmann,
T. Yamazaki,
H. Yim,
J. Zmeskal
[show abstract]
[hide abstract]
ABSTRACT: We have measured the Balmer-series x-rays of kaonic 4He atoms using novel large-area silicon drift x-ray detectors in order to study the low-energy -nucleus strong interaction. The energy of the 3d→2p transition was determined to be 6467±3(stat)±2(syst) eV. The resulting strong-interaction energy-level shift is in agreement with theoretical calculations, thus eliminating a long-standing discrepancy between theory and experiment.
Physics Letters B.
-
S. Okada,
G. Beer,
H. Bhang,
M. Cargnelli,
J. Chiba,
S. Choi,
C. Curceanu,
Y. Fukuda, T. Hanaki,
R.S. Hayano, [......],
M. Sato,
P. Schmid,
S. Suzuki,
T. Suzuki,
H. Tatsuno,
D. Tomono,
E. Widmann,
T. Yamazaki,
H. Yim,
J. Zmeskal
[show abstract]
[hide abstract]
ABSTRACT: We have measured the strong-interaction shift of 2p states of kaonic helium-4 atoms with a precision of ∼2 eV using Silicon Drift Detectors (SDDs) which lead to much improved energy resolution and signal-to-noise ratio compared to the conventional Si(Li) x-ray detector used in the past experiments. The measurement will give an answer to the longstanding “kaonic helium puzzle” and provide crucial information to understand the basis of the Akaishi-Yamazaki prediction of deeply-bound kaonic nuclei, which is one of the interpretations of the strange multibaryon candidates recently reported at KEK, DAΦNE and BNL.
Nuclear Physics A.
