Chiral dynamics and antikaon-nuclear quasibound states

Recent developments are summarised concerning low-energy interactions as they relate to the possible existence of antikaon-nuclear quasibound states. An exploratory study of antikaons bound to finite nuclei is performed, with emphasis on the evolution of such states from light to heavy nuclei (A = 16–208). The energy dependent, driving attractive interactions are constructed using the s-wave coupled-channel amplitudes involving the Λ(1405) and resulting from chiral SU(3) dynamics, plus p-wave amplitudes dominated by the Σ(1385). Effects of Pauli and short-range correlations are discussed. The decay width induced by K⁻NN two-body absorption is estimated and found to be substantial. It is concluded that -nuclear quasibound states can possibly exist with binding energies ranging from 60 to 100 MeV, but with short life times corresponding to decay widths of similar magnitudes.     

Towards exclusive antikaonic nuclear cluster search with AMADEUS

The recently proposed AMADEUS project makes use of mono energetic, low energy K⁻ beams from the upgraded high luminosity DAΦNE (e⁺e⁻)-collider of the LNF Frascati for the production of antikaon mediated deeply bound nuclear states using the (, n/p) reaction. The existing KLOE detector with a target for stopping the K⁻ surrounded by trigger detectors will be used for an exclusive detection of all particles in the production and decay processes of the antikaonic nuclei formed. Using missing mass and invariant mass spectroscopy a conclusive observation of these exotic objects should be in reach and then their properties, such as binding energies, total and partial widths, size and density could be determined, thus opening a new spectroscopy of exotic strongly bound nuclear systems.     

Hypernuclear spectroscopy via () in JLab's Hall A

Results are presented from a new experiment (E94-107) in Hall A of the Thomas Jefferson National Accelerator Facility (JLab) producing , , and using electroproduction, (e,e^′K⁺). In the hypernuclear missing-mass spectrum the experiment achieves very good energy resolution (670 keV FWHM) by exploiting the characteristics of the High Resolution spectrometer pair and the exceptional beam quality available at JLab. The spectrometers were used with the addition of an INFN provided pair of septum magnets to reach the desired small angles. Also, the Hall A standard complement of equipment was further augmented by the addition of a Ring Imaging Cherenkov detector (RICH) to achieve the best possible kaon identification.     

The intruder orbitals in superdeformed bands and alignment additivity of odd–odd nuclei in the region

The particle-number conserving (PNC) method for treating the cranked shell model with monopole and quadrupole pairing correlations is used to study the superdeformed (SD) bands observed in odd–odd nuclei in the A190 mass region. Spins are assigned to the levels in these bands. The microscopic mechanism of the ω evolution of the dynamic moment of inertia J⁽²⁾ for these SD bands are analyzed. In particular, the major roles of the j_15/2 neutron and i_13/2 proton orbitals played in the SD bands are investigated in detail by contributions to J⁽²⁾ from each cranked orbital and interference terms between two cranked orbitals. Additivity in the A190 mass region is investigated. The experimental evidence for additivity of alignments in ¹⁹²Tl can be reproduced by our calculations.     

Kaonic nuclear state search via reaction at rest on He target

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(stopped K⁻, p) or in the semi-inclusive ⁴He(stopped K⁻, 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.     

Bound states of heavy flavor hyperons

Several realistic phenomenological nucleon–nucleon interaction models are employed to investigate the possibility of bound deuteron-like states of such heavy flavor hyperons and nucleons, for which the interaction between the light flavor quark components is expected to be the most significant interaction. The results indicate that deuteron-like bound states are likely to form between nucleons and the and Ξ_cc charm hyperons as well as between Ξ hyperons and double-charm hyperons. Bound states between two Σ_c hyperons are also likely. In the case of beauty hyperons the corresponding states are likely to be deeply bound.     

Prompt fission neutron spectra of U above emissive fission threshold

Statistical model calculations of prompt fission neutron spectra (PFNS) from ²³⁵U(n,F) reaction were performed for incident neutron energies up to E_n20 MeV. Exclusive spectra of the pre-fission (pre-saddle) (n,xnf) reaction neutrons, were calculated with Hauser–Feshbach statistical model, fission and (n,xn) reaction cross section data being described consistently. Spectra of neutrons, evaporated from the fission fragments, were approximated as a sum of two Watt distributions. The reduced neutron velocity in the center-of-mass system due to the neutron emission during fragment acceleration was assumed. PFNS component due to pre-saddle neutrons is evidenced in the shape of the measured PFNS data. We show it to be strongly correlated with the emissive fission contributions to the observed fission cross sections.     

: Hadronic molecules in effective field theory

We consider the implications from the possibility that the recently observed state X(3872) is a meson–antimeson molecule. We write an effective Lagrangian consistent with the heavy-quark and chiral symmetries needed to describe X(3872). We explore the consequences of the assumption that X(3872) is a molecular bound state of D^*0 and mesons for the existence of bound states in the and channels.     

Exact correlated kinetic energy related to the electron density for two-electron model atoms with harmonic confinement

For arbitrary interparticle interaction u(r₁₂), the model two-electron atom in the title is shown to be such that the ground-state electron density ρ(r) is determined uniquely by the correlated kinetic energy density t_R(r) of the relative motion. Explicit results for t_R(r) are presented for the Hookean atom with force constant k=1/4, and also for . Possible relevance of the Hookean atom treatment to the ground state of the helium atom itself is briefly discussed.     

Discrete symmetry and CP phase of the quark mixing matrix

A simple specific pattern of the two 3×3 quark mass matrices is proposed, resulting in a prediction of the CP phase of the charged-current mixing matrix V_CKM, i.e., sin2₁(β)=0.733, which is in remarkable agreement with data, i.e., sin2₁=0.728±0.056±0.023 from Belle and sin2β=0.722±0.040±0.023 from BaBar. This pattern can be maintained by a discrete family symmetry, an example of which is D₇, the symmetry group of the heptagon.     

Materials with a desired refraction coefficient can be made by embedding small particles

A method is proposed to create materials with a desired refraction coefficient, possibly negative one. The method consists of embedding into a given material small particles. Given n₀(x), the refraction coefficient of the original material in a bounded domain , and a desired refraction coefficient n(x), one calculates the number N(x) of small particles, to be embedded in D around a point xD per unit volume of D, in order that the resulting new material has refraction coefficient n(x).     

Search for intermediate mass magnetic monopoles and nuclearites with the SLIM experiment

SLIM is a large area experiment (440 m²) installed at the Chacaltaya cosmic ray laboratory since 2001, and about 100 m² at Koksil, Himalaya, since 2003. It is devoted to the search for intermediate mass magnetic monopoles (10⁷–10¹³ GeV/c²) and nuclearites in the cosmic radiation using stacks of CR-39 and Makrofol nuclear track detectors. In four years of operation it will reach a sensitivity to a flux of about 10^-15 cm^-2 s^-1 sr^-1. We present the results of the calibration of CR-39 and Makrofol and the analysis of a first sample of the exposed detector.     

All-optical diode in an asymmetrically apodized Kerr nonlinear microresonator system

We show numerically that a Kerr nonlinear system composed of two channel waveguides coupled periodically by circular microresonators can be used as an all optical diode. The diode has low intensity requirements (50 MW/cm²) and compact dimensions (100  m).     

On localized tachyon condensation in and

We study some aspects of localized tachyon condensation on non-supersymmetric orbifolds of the form C²/Z_n and C³/Z_n. We discuss the gauged linear sigma models for these orbifolds. We show how several features of the decay of orbifolds of C³ can be realised in terms of orbifolds of C².     

Size-dependent linear and non-linear optical response of single carrier two-dimensional quantum dots

We explore the pattern of size dependence of linear and non-linear optical (NLO) responses of one-electron quantum dots in two dimensions with or without anharmonicity in the confinement potential. For some fixed values of transverse magnetic field strength (ω_c) and harmonic confinement potential (ω₀), the influence of the size of the dot on the linear (), the first (β) and the second (γ) NLO responses of the system computed through a finite field linear variational route is analysed. Size-dependent maximization is predicted to be feasible for the quadratic hyperpolarizability.     

Enhanced quantum searching via entanglement and partial diffusion

In this paper, we will define a quantum operator that performs the standard inversion about the mean only on a subspace of the system (Partial Diffusion Operator). This operator is used together with entanglement in a quantum search algorithm that runs in for searching an unstructured list of size N with M matches such that 1≤M≤N. We will show that the performance of the algorithm is more reliable than known fixed operators quantum search algorithms especially for multiple matches where we can get a solution after a single iteration with probability over 90% if the number of matches is approximately more than one-third of the search space. We will show that the algorithm will be able to handle the case where the number of matches M is unknown in advance in such that 1≤M≤N.     

The new multiplet, heavy baryon mass predictions, meson–baryon universality and effective supersymmetry in hadron spectrum

The recent measurement by CDF M(Σ_b)−M(Λ_b)=192 MeV is in striking agreement with our theoretical prediction M(Σ_b)−M(Λ_b)=194 MeV. In addition, the measured splitting agrees well with the predicted splitting of 22 MeV. We point out the connection between these predictions and an effective supersymmetry between mesons and baryons related by replacing a light antiquark by a light diquark. We discuss the theoretical framework behind these predictions and use it to provide additional predictions for the masses of spin- and spin- baryons containing heavy quarks, as well as for magnetic moments of Λ_b and Λ_c.     

Microscopic theory of dissipation for slowly time-dependent mean field potentials

We study the dissipation rate in systems of nucleons bound by a slowly time-dependent mean-field potential and slightly interacting between themselves. Starting from the many-body linear response formula we evaluate an expression for in terms of the pure shell-model quantities and the nucleon–nucleon collision rate Γ. The application of the classical sum rule leads then to an expression for in terms of the classical-path integral with the weighting function including Γ. For vanishing Γ this expression reduces to the Koonin–Randrup Knudsen-gas formula. For simplified Skyrme interactions the classical approximation for the Γ itself is obtained. In leptodermous systems the classical-path expression for decomposes into the wall formula and the multiple-reflection term owing to incomplete randomization of particle motion between consecutive encounters with the boundary. The mean-free path and temperature dependence of dissipation is analyzed for small-amplitude distortions of spherical cavities.     

hypernuclei based on the ESC04 model

Structures of S=−2 many-body states (double-Λ and Ξ hypernuclei) are investigated on the basis of G-matrix interactions derived from the recently-developed extended-soft-core model (ESC04d). ΛΛ–ΞN mixing effects in ⁶_ΛΛHe, ⁵_ΛΛH and ⁵_ΛΛHe are investigated with use of three-body models. Possible Ξ hypernuclei are investigated systematically with Ξ-core folding potentials derived from ΞN G-matrix interactions. A four-body narrow Ξ⁰–Ξ⁻ mixed state, specific to ESC04d, is discussed.