arXiv subjects

T. Uchino

Publications and source records attributed to T. Uchino.

6 recordsLinked to original sources

arXiv2015

Two, three, many body systems involving mesons. Multimeson condensates

In this talk we review results from studies with unconventional many hadron systems containing mesons: systems with two mesons and one baryon, three mesons, some novel systems with two baryons and one meson, and finally systems with many vector mesons, up to six, with their spins aligned forming states of increasing spin. We show that in many cases one has experimental counterparts for the states found, while in some other cases they remain as predictions, which we suggest to be searched in BESIII, Belle, LHCb, FAIR and other facilities.

hep-ph↗

arXiv2015

Baryon states with hidden charm in the extended local hidden gauge approach

The s-wave interaction of $\bar{D} Λ_c, \bar{D} Σ_c, \bar{D} Λ_c, \bar{D}{}^* Σ_c$ and $\bar{D}Σ^*_c, \bar{D}{}^*Σ^*_c$, is studied within a unitary coupled channels scheme with the extended local hidden gauge approach. In addition to the Weinberg-Tomozawa term, several additional diagrams via the pion-exchange are also taken into account as box potentials. Furthermore, in order to implement the full coupled channels calculation, some of the box potentials which mix the vector-baryon and pseudoscalar-baryon sectors are extended to construct the effective transition potentials. As a result, we have observed six possible states in several angular momenta. Four of them correspond to two pairs of admixture states, two of $\bar{D}Σ_c$ - $\bar{D}{}^*Σ_c$ with $J^P = 1/2^-$, and two of $\bar{D}Σ^*_c$ - $\bar{D}{}^*Σ^*_c$ with $J^P = 3/2^-$. Moreover, we find a $\bar{D}{}^* Σ_c$ resonance which couples to the $\bar{D}Λ_c$ channel and one spin degenerated bound state of $\bar{D}{}^*Σ^*_c$ with $J^P = 1/2^-, 5/2^-$.

hep-ph↗

arXiv2015

Baryon states with open charm in the extended local hidden gauge approach

In this paper we examine the interaction of $D N$ and $D^* N$ states, together with their coupled channels, by using an extension of the local hidden gauge formalism from the light meson sector, which is based on heavy quark spin symmetry. The scheme is based on the use of the impulse approximation at the quark level, with the heavy quarks acting as spectators, which occurs for the dominant terms where there is the exchange of a light meson. The pion exchange and the Weinberg-Tomozawa interactions are generalized and with this dynamics we look for states generated from the interaction, with a unitary coupled channels approach that mixes the pseudoscalar-baryon and vector-baryon states. We find two states with nearly zero width which are associated to the $Λ_c(2595)$ and $Λ_c(2625)$. The lower state, with $J^P = 1/2^-$, couples to $D N$ and $D^* N$, and the second one, with $J^P = 3/2^-$, to $D^* N$. In addition to these two $Λ_c$ states, we find four more states with $I=0$, one of them nearly degenerate in two states of $J=1/2,\ 3/2$. Furthermore we find three states in $I=1$, two of them degenerate in $J=1/2, 3/2$.

hep-ph↗

arXiv2013

Description of $ρ(1700)$ as a $ρK \bar{K}$ system with the fixed center approximation

We study the $ρK\bar{K}$ system with an aim to describe the $ρ(1700)$ resonance. The chiral unitary approach has achieved success in a description of systems of the light hadron sector. With this method, the $K \bar{K}$ system in the isospin sector $I=0$, is found to be a dominant component of the $f_0 (980)$ resonance. Therefore, by regarding the $K\bar{K}$ system as a cluster, the $f_0 (980)$ resonance, we evaluate the $ρK\bar{K}$ system applying the fixed center approximation to the Faddeev equations. We construct the $ρK$ unitarized amplitude using the chiral unitary approach. As a result, we find a peak in the three-body amplitude around 1739 MeV and a width of about 227 MeV. The effect of the width of $ρ$ and $f_0 (980)$ is also discussed. We associate this peak to the $ρ(1700)$ which has a mass of $1720 \pm 20$ MeV and a width of $250 \pm 100$ MeV.

hep-ph↗

arXiv2010

Multi-fold Enhancement of Quantum Dot Luminescence in a Plasmonic Metamaterial

We report that hybridizing semiconductor quantum dots with plasmonic metamaterial leads to a multi-fold intensity increase and narrowing of their photoluminescence spectrum. The luminescence enhancement is a clear manifestation of the cavity quantum electrodynamics Purcell effect that can be controlled by the metamaterial's design. This observation is an essential step towards understanding loss compensation in metamaterials with gain media and for developing metamaterial-enhanced gain media.

physics.optics↗

arXiv1992

Correlation Functions in Two-Dimensional Dilaton Gravity

The Liouville approach is applied to the quantum treatment of the dilaton gravity in two dimensions. The physical states are obtained from the BRST cohomology and correlation functions are computed up to three-point functions. For the $N=0$ case (i.e., without matter), the cosmological term operator is found to have the discrete momentum that plays a special role in the $c=1$ Liouville gravity. The correlation functions for arbitrary numbers of operators are found in the $N=0$ case, and are nonvanishing only for specific ``chirality'' configurations.

hep-th↗