Exotic decays of strangelets

The stability of strange matter depends on the implicit assumption that baryon number is conserved. We examine the relevant effective operators which allow strangelets to decay by violating the conservation of baryon number. From the experimental lower limit of 10²⁵ years on the stability of nuclei, we find a lower limit of the order 10⁶ years on the stability of strangelets against such exotic decays.     

Intermediate mass strangelets are positively charged

For a limited range of parameters, stable strange quark matter may be negatively charged in bulk due to one gluon exchange interactions. However, the reduction in strange quark occupation in the surface layer, which is responsible for surface tension, more than compensates this for intermediate mass strangelets, which therefore always have positive quark charge (e.g., for a baryon number between 10(2) and 10(18) assuming alpha(S) = 0.9). While details are sensitive to the choice of renormalization, the general conclusion is not. This rules out a scenario where negatively charged strangelets produced in ultrarelativistic heavy ion colliders might grow indefinitely with potentially disastrous consequences.     

First search for positive strangelets with the E864 spectrometer

The first search for strangelets conducted by experiment BNL-E864 is presented [1]. The analysis uses over 26.5 million “central” events recorded for the “positive strangelet” search from the first (Fall 1994) run of the experiment. The full apparatus was not installed for this run, but the tracking portion of the apparatus which was present for the 1994 run performed to the expectations of our proposal. We observed 25 Z=1 high mass candidates in a mass range of 10 GeV to 200 GeV. The number and character of observed high mass candidates are consistent with background expected from Monte Carlo programs for the 1994 configuration of the detector, and thus limits are placed on strangelet production. The results place a significant limit on the existence of high mass strangelets.     

Model for describing the production of Centauro events and strangelets in heavy-ion collisions

A phenomenological model for describing the production of Centauro events in relativistic heavy-ion collisions is discussed. The model provides quantitative predictions for kinematical variables, for the baryon number, and for the masses of a Centauro fireball and of its decay products. A Centauro fireball decays predominantly into nucleons, strange hyperons, and possibly strangelets. Centauro events in Pb + Pb collisions at the LHC energy are simulated for the CASTOR detector. The signatures of these events are discussed in detail.     

Properties of strangelets in a new quark mass confinement model with one-gluon-exchange interaction

The properties of strangelets at zero temperature with a new quark model that includes both the confinement and one-gluonexchange interactions is studied in a fully self-consistent method.The charge and parameter dependence of the stability of strangelets are discussed.It is found that the one-gluon-exchange interaction lowers the energy of a strangelet,and consequently allows the strangelet to be absolutely stable.The stable strangelet radius in the present model is smaller in comparison with the absence of one-gluon-exchange interaction,and can thus be much less than that of a normal nucleus with the same baryon number,according to the strength of the confinement and one-gluon-exchange interactions.     

The sliding singlet

Supersymmetric grand unified models with a sliding singlet are considered. We review the argument that the sliding does not work in models with large supersymmetry breaking. Then we consider the possibility of using a sliding singlet with low-energy supersymmetry breaking. A number of problems with such a program are noted and illustrated in simple examples. Using the experience gained from these examples a realistic model is constructed and analyzed.     

射流式单重态氧发生器理论模型

 射流式单重态氧发生器(JSOG)是化学氧碘激光器十分重要的能源部分,它主要是通过解气相、液相扩散方程来求解发生器出口的氯的利用率和单重态氧的产率。在实际工作中的射流发生器非常复杂,其扩散方程和边界条件为非线性,非齐次边界条件,非齐次泛定方程组,求解难度较大。通过边界条件,采用试探解的方法,解得氯、总氧、单重态氧的气相、液相扩散方程,得到了氯的利用率,及单重态氧产率的解析解,与实验结果基本相符。     

Magnetism in singlet ground states

The spin‐gap phenomenon is a key characteristic of high T_c superconducting cuprates, whose experimental results are summarized and discussed in the context of the slave‐boson mean field theory of the extended t–J model. It is seen that there exists satisfactory agreement between theory and experiments in bilayer cuprates. As regards the apparent absence of the spin‐gap in single layer La_2-xSr_xCuO₄ (LSCO), the possible roles played by disorder have been pointed out in view of the recent neutron scattering experiment on other spin singlet systems, the spin‐Peierls CuGeO₃ and two‐leg ladders. This revised version was published online in July 2006 with corrections to the Cover Date.     

Spin singlet mott states and evidence for spin singlet quantum condensates of spin-one bosons in lattices

We have investigated spin singlet Mott states of spin-one bosons with antiferromagnetic interactions. These spin singlet states do not break rotational symmetry and exhibit remarkably different macroscopic properties compared with nematic Mott states of spin-one bosons. We demonstrate that the dynamics of spin singlet Mott states is fully characterized by even- or odd-class quantum dimer models. The difference between spin singlet Mott states for even and odd numbers of atoms per site can be attributed to a selection rule in the low energy sectors of on-site Hilbert spaces; alternatively, it can also be attributed to an effect of Berry’s phases on bosonic Mott states. We also discuss evidence for spin singlet quantum condensate of spin-one atoms. Our main finding is that in a projected spin singlet Hilbert space, the low energy physics of spin-one bosons is equivalent to that of a Bose-Hubbard model for spinless bosons interacting via Ising gauge fields. The other major finding is spin-charge separation in some one-dimensional Mott states. We propose charge-e spin singlet superfluid for an odd number of atoms per lattice site and charge-2e spin singlet superfluid for an even number of atoms per lattice site in one-dimensional lattices. All discussions in this article are limited to integer numbers of bosons per site.     

The search for cosmic strangelets with the supersonic concorde and with JACEE's circumpolar balloon flight in Antarctica

The search for cosmic strangelet nuclei was carried out by two experiments with emulsion chambers. A balloon-borne JACEE emulsion chamber was flown at 3.5 g/cm² for 200 h in Antarctica (JACEE-10 experiment) and the Concorde flights were made by ECHOS at an atmospheric depth of 110 g/cm² between Paris and New York. No nuclei withZ⩾30 survived after traversing 60–120 g/cm² of the detector materials in the JACEE instruments. No evidence for a long mean free path were found in the zenith angle distribution forZ/β⩾26 nuclei. The exposure factor used by the JACEE was 72 m²hsr. The intensity upperbounds,I⩽(2.2–9.7)×10⁻²/m²h sr, were obtained for strangelets having an atmospheric attenuation length of 220−50 g/cm², which corresponds to the case for mass numberA=100–10000 andZ/β > 13. Concorde experiments (ECHOS) used both a thin and a thick emulsion chamber. The total exposure was 209 m² h sr and no candidates with chargeZ⩾30 were found. The largest track hadZ/β=28.6±1.29 withβ ∼ 1. Nuclei observed with charge 13⩽Z⩽30 were consistent with the survival intensity of ordinary nuclei. The flux bounds from the ECHOS experiments were I⩽(2.1–5.0) x 10⁻²/m²h for strangelets with mass number 100⩽A⩽1000.     

Generation of a two-photon singlet beam

Controlling the pump beam transverse profile in multimode Hong-Ou-Mandel interference, we generate a "localized" two-photon singlet state, in which both photons propagate in the same beam. This type of multiphoton singlet beam may be useful in quantum communication to avoid decoherence. We show that although the photons are part of the same beam, they are never in the same plane-wave mode, which is characterized by spatial antibunching behavior in the plane normal to the propagation direction.     

Supersymmetric cosmology with a gauge singlet

Cosmological constraints on a supersymmetric version of the standard model coupled to N = 1 supergravity are derived, in which gauge symmetry breaking is triggered by a Higgs singlet. Possible neutralino dark matter candidates are emphasized. In particular, the fermionic partner of the Higgs singlet is often the lightest supersymmetric particle, with a relic abundance near the critical closure density.     

The lowest singlet state of dibenzofuran

The vapor absorption of dibenzofuran has been reexamined, and the spectrum and lifetime of the vapor fluorescence have been measured. Also measured were the polarized absorption in durene host and the depolarized absorption, fluorescence, and phosphorescence in cyclododecane host at 4 K. The fluoresecent state is that corresponding to the 3000 Å absorption in all media, and no evidence was found for a weak transition at 3175 Å as reported by Pinkham and Wait. The mixed crystal spectra are heavily perturbed, but from the polarizations observed in durene the 3000 Å transition is assigned as ${}^1\text{B}{}_2\text{←}{}^1\text{A}{}_1$ (long axis polarized).