Restricted geometry optimization for estimating stabilization energies of polycyclic aromatic hydrocarbons

At the B3LYP/6‐31G* level, our program of geometry optimization under the restrictions of π‐orbital interactions was applied to five homologous series such as acene‐, phenanthrene, triphenylene, chrysene, benzopyrene series, and seven additional molecules such as tri‐ and tetra‐benzanthracene, benzo‐ and naphtho‐pentaphene, dibenzopentacene and tribenzotetracene, providing each of the 35 polycyclic aromatic hydrocarbons (PAHs) with two types of localized reference geometries: (i) the ‘GL’ geometry where all double bonds are localized and (ii) m different ‘GE‐m’ geometries, where only a specific pair of double bonds are permitted to conjugate and all other bonds are localized.. Each GE‐m resulted from the local π interaction between a pair of double bonds in the GL geometry. The total sum of molecular energy differences, ([E(Ground) ? E(GL)] ? Σ[E(GE‐m) ? E(GL)]), is defined as the extra stabilization energy (ESE) for a PAH. The corrected ESE (CESE) then resulted from considering π interactions between pairs of nonbonded double bonds. In this work, the position, energy and GL sextet rules were developed to ensure that the GL geometry chosen from its candidates as well as the GE‐m geometries is no longer arbitrary. Therefore, it is the GL and GE‐m geometries of the PAH itself, rather than nonaromatic compounds, that serve as reference structures for calculating CESE. As a result, for each of the four homologous series (acene, phenanthrene, triphenylene, and benzopyrene), CESE/π can be fitted as a linear function of the p band frequency . For each of the four isomeric series with molecular formulas of C₁₈H₁₂, C₂₂H₁₄, C₂₆H₁₆, and C₃₀H₁₈, CESE/π can also be fitted as a second‐order polynomial function of the p band frequency as well as of the number of GL sextets. Copyright © 2009 John Wiley & Sons, Ltd.     

Universal extra dimensions on real projective plane

We propose a six-dimensional Universal Extra Dimensions (UED) model compactified on a real projective plane RP²${\mathit{RP}}^2$, a two-sphere with its antipodal points being identified. We utilize the Randjbar-Daemi–Salam–Strathdee spontaneous sphere compactification with a monopole configuration of an extra UX₍₁₎$U{(1)}_X$ gauge field that leads to a spontaneous radius stabilization. Unlike the sphere and the S²/Z₂$S^2/Z_2$ orbifold compactifications, the massless UX₍₁₎$U{(1)}_X$ gauge boson is safely projected out. We show how a compactification on a non-orientable manifold results in a chiral four-dimensional gauge theory by utilizing 6D chiral gauge and Yukawa interactions. The resultant Kaluza–Klein mass spectra are distinct from the ordinary UED models compactified on torus. We briefly comment on the anomaly cancellation and also on a possible dark matter candidate in our model.     

Supersymmetry at DØ and other new phenomena searches in Run II

The Run II of the DØ experiment was started in March 2001. The first preliminary results on searches for new physics are presented, with a luminosity of ～ 10 pb^?1 from the data collected in 2001–2002. We report results in mSUGRA (jets + missingE_T channel), GMSB (diphotons), RPV (trileptons and like sign dileptons) and large extra dimensions (dielectrons and diphotons).     

Identifying new physics contributions in the Higgs sector at linear <Emphasis Type="Italic">e</Emphasis><Superscript>+</Superscript><Emphasis Type="Italic">e</Emphasis><Superscript>−</Superscript> colliders

Loop-driven decay modes of the Higgs are sensitive to new physics contributions because of new particles in the loops. To highlight this we look at the dilepton-dijet signal in the dominant Higgs production channel at a linear e ⁺ e ⁻ collider. We show that by taking a simple ratio between cross-sections of two different final states such contributions can be very easily identified.      

Brane Formation and Cosmological Constraint on the Number of Extra Dimensions

Special relativity is generalized to extra dimensions and quantized energy levels of particles are obtained. By calculating the probability of particles' motion in extra dimensions at high temperature of the early universe, it is proposed that the branes may have not existed since the very beginning of the universe, but formed later. Meanwhile, before the formation, particles of the universe may have filled in the whole bulk, not just on the branes. This scenario differs from that in the standard big bang cosmology in which all particles are assumed to be in the 4D spacetime. So, in brane models, whether our universe began from a 4D big bang singularity is questionable. A cosmological constraint on the number of extra dimensions is also given which favors N ≥ 7.     

Letter: Can Geodesics in Extra Dimensions Solve the Cosmic Light Speed Limit?

It is shown that our 3 + 1 Brane Einstein Universe is a trapped shell in a Higher Dimensional spacetime (Bulk). It is also shown that the Israel Condition acts like a pressure to trap matter in Einstein's Universe, and that if we overcome this pressure, we can make a particle leave Einstein's Universe and enter the Bulk. The conditions that allow the entrance to the Bulk permit its use to send signals or particles faster than the speed of the light, when seen from the Brane due to Brane Lensing. However, in the Bulk the particles remain subluminal. Our model differs from all the standard Braneworlds models, because all matter is trapped in this 3 + 1 Einstein Shell, independently of what the Standard Model might impose. What we propose is a new Braneworld Model using some of the features of the Chung-Freese Model, plus a way to overcome the pressure from the Israel Condition. Our model will remotely resemble the Davoudias Hewett, Rizzo modifications made to Randall-Sundrum Model that allow fermions (not only gravitons) to enter the Bulk, although we must outline that we are proposing a different idea.     

Harmonic 2-spheres with pairs of extra eigenfunctions

In the present paper, deformations of harmonic 2-spheres in the unit -sphere respecting the degree are studied. The limit maps of such deformations are characterized as harmonic maps with extra eigenfunctions. The space of harmonic 2-spheres in with fixed degree is described in terms of such deformations and the limit maps.

     

Event-shape of dileptons plus missing energy at a linear collider as a supersymmetry/Arkani-Hamed-Dimopoulos-Dvali discriminant

An event-shape analysis of the dileptons in the process e ⁺ e ⁻ → ℓ⁺ℓ⁻ , studied in ILC or CLIC, can clearly discriminate between a supersymmetric or a large extra dimensional (ADD) production mechanism.      

稀土元素对低硫氧合金结构钢冲击韧性的影响机制

利用数字化冲击试验装置和微观分析手段,研究了La,Ce对低硫氧合金结构钢冲击性能的影响,并对影响机制进行了分析。结果表明,稀土元素有改善低硫氧合金结构钢冲击韧性的作用,适宜的稀土含量大约为0.005%。稀土元素通过净化晶界和变质夹杂物,将提高晶界的强度,减少裂纹通过缺陷的贯通而扩展的可能,从而使材料承受冲击载荷时可以吸收更多的裂纹扩展的能量。稀土过量时,将弱化晶界,形成脆硬的磷化物、铁-稀土金属间化合物等,弱化材料的冲击性能。     

A New Type of Accessible Environmental Influences on Neutrino Oscillation

Considering a new type of environment influences,we use a two-energy-level(ν1-ν2) quantum system to investigate neutrino oscillations in medium.Besides the matter effects derived by Wolfenstein,there may exist extra terms due to a unitary evolution of the system between pure and mixed states,so the evolution equation is modified obviously.We show that the extra terms may play some role and induce observable effects in solar neutrino problem,especially,in the long baseline neutrino oscillation experiments which are under serious consideration recently,if the parameters fall into a suitable region.