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Yamagata-Sekihara, J

Publications and source records attributed to Yamagata-Sekihara, J.

6 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2011

Hadronic particles made of multi-{rho}(770) mesons

We summarize the work [1] where we studied the few body system made of several {rho}(770) mesons. Based on the very strong interaction of two {rho}(770) vector mesons in spin 2 and isospin 0, we show that the resonances {rho}3(1690)(3{sup --}), f4(2050)(4{sup ++}), {rho}5(2350)(5{sup --}) and f6(2510)(6{sup ++}) can be interpreted as few body systems made of an increasing number of {rho}(770) particles. The fixed center approximation of the Faddeev equations is used in order to write the multi-body interaction in terms of the elementary two-body scattering amplitudes. Very good agreement with the experimental masses is found. An extension of the model to include also the interaction with K*(895) is discussed.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2011

KNN system with chiral dynamics

We have performed a calculation of the scattering amplitude for the three-body system KNN assuming K scattering against a NN cluster using the fixed center approximation to the Faddeev equations. The KN amplitudes, which we take from chiral unitary dynamics, govern the reaction and we find a KNN amplitude that peaks around 40 MeV below the KNN threshold, with a width in |T|{sup 2} of the order of 50 MeV for spin 0 and has another peak around 27 MeV with similar width for spin 1. The results are in line with those obtained using different methods but implementing chiral dynamics. The simplicity of the approach allows one to see the important ingredients responsible for the results. In particular, we show the effects from the reduction of the size of the NN cluster due to the interaction with the K and those from the explicit consideration of the {pi}{Sigma}N channel in the three-body equations.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2011

Couplings in coupled channels versus wave functions in the case of resonances: Application to the two {Lambda}(1405) states

In this paper we develop a formalism to evaluate wave functions in momentum and coordinate space for the resonant states dynamically generated in a unitary coupled channel approach. The on-shell approach for the scattering matrix, commonly used, is also obtained in quantum mechanics with a separable potential, which allows one to write wave functions in a trivial way. We develop useful relationships among the couplings of the dynamically generated resonances to the different channels and the wave functions at the origin. The formalism provides an intuitive picture of the resonances in the coupled channel approach, as bound states of one bound channel, which decays into open ones. It also provides an insight and practical rules for evaluating couplings of the resonances to external sources and how to deal with final state interaction in production processes. As an application of the formalism we evaluate the wave functions of the two {Lambda}(1405) states in the {pi}{Sigma}, KN, and other coupled channels. It also offers a practical way to study three-body systems when two of them cluster into a resonance.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2010

Experimental status of deeply bound kaonic states in nuclei

We review recent claims of the existence of deeply bound kaonic states in nuclei. Also we study in details the (K{sup -},p) reaction on {sup 12}C with 1 GeV/c momentum kaon beam, based on which a deep kaon nucleus optical potential was claimed in [1]. In our Monte Carlo simulation of this reaction we include not only the quasi-elastic K{sup -}p scattering, as in [1], but also K{sup -} absorption by one and two nucleons followed by the decay of the hyperon in {pi}N, which can also produce strength in the region of interest. The final state interactions in terms of multiple scattering of the K{sup -},p and all other primary particles on their way out of the nucleus is also considered. We will show that all these additional mechanisms allow us to explain the observed spectrum with a ''standard'' shallow kaon nucleus optical potential obtained in chiral models.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2010

Mesonic and nonmesonic absorption of kaon in nuclear matter and {Lambda}(1405) doorway process

The mesonic and nonmesonic absorptions of kaon into nuclear systems are investigated from a viewpoint of {Lambda}(1405) doorway process. Using a one-meson exchange model in the calculation of the nonmesonic {Lambda}(1405)N{yields}YN transition and using the chiral unitary approach for the description of the {Lambda}(1405), we obtain the nonmesonic transition ratio {Gamma}{sub {Lambda}N}/{Gamma}{sub {Sigma}}{sup 0}{sub N{approx_equal}}1.2 which is almost independent of the nucleon density, and find the total nonmesonic decay width of the {Lambda}(1405) in uniform nuclear matter to be 22 MeV at the normal density. We also calculate the absorption for stopped K{sup -} in nuclear matter, and find that the ''formation rate'' of {Lambda}(1405) is important for the density dependence and the absolute value of the absorption potential of kaon in nuclear matter.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2010

Wave functions for dynamically generated resonances; the two {Lambda}(1405) and {Lambda}(1670)

In this work we develop a formalism to evaluate wave functions in momentum and coordinate space for the resonant states dynamically generated in a unitary coupled channel approach. The on shell approach for the scattering matrix, commonly used, is also obtained in Quantum Mechanics with a separable potential, which allows one to write wave functions in a trivial way. We develop useful relationships among the couplings of the dynamically generated resonances to the different channels and the wave functions at the origin. The formalism provides an intuitive picture of the resonances in the coupled channel approach, as bound states of one bound channel, which decays into open ones. It also provides an insight and practical rules for evaluating couplings of the resonances to external sources and how to deal with final state interaction in production processes. As an application of the formalism we evaluate the wave functions of the two {Lambda}(1405) states in the {pi}{Sigma}, K-barN and other coupled channels. It also offers a practical way to study three body systems when two of them cluster into a resonance.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗