119192598
Evidence for a new Sigma* resonance with J**P = 1/2- in the old data of K- p ---> Lambda pi+ pi- reaction
Distinctive patterns are predicted by quenched quark models and unquenched quark models for the lowest SU(3) baryon nonet with spin parity J P = 1/2 - . While the quenched quark models predict the lowest 1/2- ∑* resonance to be above 1600 MeV, the unquenched quark models predict it to be around ∑*(1385) energy. Here we reexamine some old data of the K - p → ∧π + π - reaction and find that besides the well-established ∑*(1385) with J p = 3/2 + , there is indeed some evidence for the possible existence of a new ∑* resonance with J P = 1/2- around the same mass but with broader decay width. Higher statistic data on relevant reactions are needed to clarify the situation.
51753903
Interaction of vector mesons with baryons and nuclei
After some short introductory remarks on particular issues on the vector mesons in nuclei, in this paper we present a short review of recent developments concerning the interaction of vector mesons with baryons and with nuclei from a modern perspective using the local hidden gauge formalism for the interaction of vector mesons. We present results for the vector baryon interaction and in particular for the resonances which appear as composite states, dynamically generated from the interaction of vector mesons with baryons, taking also the mixing of these states with pseudoscalars and baryons into account. We then venture into the charm sector, reporting on hidden charm baryon states around 4400 MeV, generated from the interaction of vector mesons and baryons with charm, which have a strong repercussion on the properties of the J/�N interaction. We also address the interaction of K ∗ with nuclei and make suggestions to measure the predicted huge width in the medium by means of the transparency ratio. The formalism is extended to study the phenomenon of J/ψ suppression in nuclei via J/ψ photoproduction reactions.
118372351
Role of the possible $\Sigma^*(\frac{1}{2}^-)$ state in the $\Lambda p \to \Lambda p \pi^0$ reaction
The $\Lambda p \to \Lambda p \pi^0$ reaction near threshold is studied within an effective Lagrangian method. The production process is described by single-pion and single-kaon exchange. In addition to the role played by the $\Sigma^*(1385)$ resonance of spin-parity $J^P = 3/2^+$, the effects of a newly proposed $\Sigma^*$ ($J^P = 1/2^-$) state with mass and width around $1380$ MeV and $120$ MeV are investigated. We show that our model leads to a good description of the experimental data on the total cross section of the $\Lambda p \to \Lambda p \pi^0$ reaction by including the contributions from the possible $\Sigma^*(\frac{1}{2}^-)$ state. However, the theoretical calculations by considering only the $\Sigma^*(1385)$ resonance fail to reproduce the experimental data, especially for the enhancement close to the reaction threshold. On the other hand, it is found that the single-pion exchange is dominant. Furthermore, we also demonstrate that the angular distributions provide direct information of this reaction, hence could be useful for the investigation of the existence of the $\Sigma^*(\frac{1}{2}^-)$ state and may be tested by future experiments.
116901981
Further evidence for the Sigma* resonance with J**P = 1/2- around 1380-MeV
The unquenched quark models predict the new particle $\Sigma^*$ with spin parity $J^P=1/2^-$ and its mass is around the well established $\Sigma^*(1385)$ with $J^P=3/2^+$. Here by using the effective Lagrangian approach we study \kp\ reaction at the range of $\Lambda^{*}(1520)$ peak, comparing the resulting total cross section, and $\pi^+\pi^-$, $\Lambda\pi^+$, $\Lambda\pi^-$ invariant squared mass distributions for various incident $K^-$ momenta, as well as the production angular distribution of the $\Lambda$ with the data from the Lawrence Berkeley Laboratory 25-inch hydrogen bubble chamber, we find that, apart from the existing resonance $\Sigma^{*}(1385)$ with $J^P=3/2^+$, there is a strong evidence for the existence of the new resonance $\Sigma^{*}$ with $J^P=1/2^-$ around 1380 MeV. Higher statistic data on relevant reactions are needed to clarify the situation.
118488848
Photoproduction of bound states with hidden charm
The photo-production of $J/\Psi$-$^3He$ bound state ($[^3He]_{J/\Psi}$) on a $^4He$ target has been investigated using the impulse approximation. The calculations have been performed using several $\gamma+N \rightarrow J/\Psi +N$ models based on the Pomeron-exchange and accounting for the pion-exchange mechanism at low energies. The $J/\Psi$ wavefunctions in $[^3He]_{J/\Psi}$ are generated from various $J/\Psi$-nucleus potentials which are constructed by either using a procedure based on the Pomeron-quark coupling mechanism or folding a $J/\Psi$-N potential ($v_{J/\Psi,N}$) into the nuclear densities. We consider $v_{J/\Psi,N}$ derived from the effective field theory approach, Lattice QCD, and Pomeron-quark coupling mechanism. The upper bound of the predicted total cross sections is about $0.1 - 0.3$ pico-barn. We also consider the possibility of photo-production of a six quark-$J/\Psi$ bound state ($[q^6]_{J/\Psi})$ on the $^3He$ target. The Compound Bag Model of $NN$ scattering and the quark cluster model of nuclei are used to estimate the $[q^6]$-N wavefunction in $^3He$ by imposing the condition that the calculated $^3He$ charge form factor must be consistent with what is predicted by the conventional nuclear model. The upper bound of the predicted total cross sections of $\gamma + ^3He \rightarrow [q^6]_{J/\Psi} +N$ is about 2 - 4 pico-barn, depending on the model of $\gamma+N \rightarrow J/\Psi +N$ used in the calculations. Our results call for the need of precise measurements of $\gamma+p \rightarrow J/\Psi +p$ and also the $\gamma+^2H\rightarrow J/\Psi +n + p $ reactions near the threshold.
119310679
Nucleon Resonances with Hidden Charm in Coupled-Channel Models
The model dependence of the predictions of nucleon resonances with hidden charm is investigated. We consider several coupled-channel models which are derived from relativistic quantum field theory by using (1) a unitary transformation method, and (2) the three-dimensional reductions of Bethe-Salpeter Equation. With the same vector meson exchange mechanism, we find that all models give very narrow molecular-like nucleon resonances with hidden charm in the mass range of 4.3 GeV < MR < 4.5 GeV, in consistent with the previous predictions.
119228450
Holographic superconductor on Q-lattice
A bstractWe construct the simplest gravitational dual model of a superconductor on Q-lattices. We analyze the condition for the existence of a critical temperature at which the charged scalar field will condense. In contrast to the holographic superconductor on ionic lattices, the presence of Q-lattices will suppress the condensate of the scalar field and lower the critical temperature. In particular, when the Q-lattice background is dual to a deep insulating phase, the condensation would never occur for some small charges. Furthermore, we numerically compute the optical conductivity in the superconducting regime. It turns out that the presence of Q-lattice does not remove the pole in the imaginary part of the conductivity, ensuring the appearance of a delta function in the real part. We also evaluate the gap which in general depends on the charge of the scalar field as well as the Q-lattice parameters. Nevertheless, when the charge of the scalar field is relatively large and approaches the probe limit, the gap becomes universal with ωg ≃ 9Tc which is consistent with the result for conventional holographic superconductors.
117395921
An analytical study of the O(N) nonlinear sigma models on lattice
In the variational cumulant expansion approach, we calculate the internal energy for the d-dimensional O(N) nonlinear a models on lattice. Specially, me give the results for two-dimensional O(3), O(4) and O(5) models. A comparison with Monte-Carlo (MC) data is also presented. Our formalism can given the results for O(N) nonlinear cr models (for any N and any dimensionality d) straightforwardly.
16008283
A New Approach to Construct the Operator on Lattice for the Calculation of Glueball Masses
We develop a new approach to construct the operator on lattice for the calculation of glueball mass, which is based on the connection between the continuum limit of the chosen operator and the quantum number $J^{PC}$ of the state studied. The spin of the state studied is then determined uniquely and directly in numerical simulation. Furthermore, the approach can be applied to calculate the mass of glueball states (ground or excited states) with any spin $J$ including $J\geq 4$. Under the quenched approximation, we present pre-calculation results for the masses of $0^{++}$ state and $2^{++}$ state, which are $1754(85)(86)MeV$ and $2417(56)(117)MeV$, respectively.
6976924
(Non)-supersymmetric Marginal Deformations from Twistor String Theory
The tree-level amplitudes in the β-deformed supersymmetric gauge theory are derived from twistor string theory. We first show that a simple generalization of [M. Kulaxizi, K. Zoubos, Marginal deformations of N=4 SYM from open/closed twistor strings, Nucl. Phys. B 738 (2006) 317, hep-th/0410122] gives us the desired results for all the tree-level amplitudes up to first order in the deformation parameter β. Then we provide a new proposal which matches field theory to all orders of β. With our deformed twistor string theory, it can be shown that integration over connected instantons and disconnected instantons remain equivalent. The tree-level amplitudes in the non-supersymmetric γ-deformed theory can be obtained using a similar deformation of the twistor string. Finally, we find improved twistor string results for the tree-level purely gluonic amplitudes in theories with more general marginal deformations.
118600500
On the generality of the LLM geometries in M-theory
In this note we revisit the Lin, Lunin, Maldacena (LLM) class of d = 11 supergravity solutions with symmetry SO(6) × SO(3) × R, but generalise to allow for all fluxes consistent with the isometries. Using the Killing spinor equation, we prove there are no supersymmetric geometries with additional fluxes beyond the LLM ansatz. In addition, the LLM relationship between Killing spinors, ϵ− = − γ5ϵ+, may be seen as a consequence of identifying two Killing directions identified through the Killing spinor equation corresponding to candidate R-symmetry directions.