An investigation of hadronization mechanism at a Z~0 factory

We briefly review the hadronization pictures adopted in the LUND String Fragmentation Model (LSFM),Webber Cluster Fragmentation Model (WCFM) and Quark Combination Model (QCM),respectively.Predictions of hadron multiplicity,baryon to meson ratios and baryon-antibaryon flavor correlations,especially those related to heavy hadrons at a Z 0 factory obtained by LSFM and QCM,are reported.     

A shock tube and modeling study on ignition delay times of pyridine under O2/CO2 atmospheres at elevated pressures

Pressurized oxy-fuel combustion has been attracting increasing attentions due to its improved efficiency and low cost. The present study reports ignition delay times (IDTs) of pyridine under O₂/CO₂ atmospheres within a temperature range from 1202 to 1498 K at pressures from 2.2 to 10 bar for equivalence ratios of 0.5, 1.0, and 2.0. The experimental results were compared with the IDTs of pyridine under O₂/Ar atmospheres from MacNamara et al.. The comparison results indicate that the IDTs of pyridine under O₂/CO₂ atmospheres are evident longer than those under O₂/Ar atmospheres even at low pressure. A modified kinetic model (HUST pyridine Model) was proposed based on our previous mechanism. HUST pyridine Model predicted well the IDTs under both O₂/CO₂ and O₂/Ar atmospheres obtained in shock tubes and the species profiles under both O₂/CO₂ and O₂/N₂ atmospheres obtained in plug flow reactors. HUST pyridine Model, Alzueta Model, and Pyridine LTO Model were evaluated. The results show that the performance of HUST pyridine Model is much better than Alzueta Model, and Pyridine LTO Model. The main reason is that the net reaction rate of C₅H₅N + O = C₅H₄N + OH in HUST pyridine Model is much faster than that in Aluzeta Model. The effect of CO₂ on the ignition of pyridine at elevated pressures has been analyzed in detail. The oxidation pathways of pyridine are also analyzed at different pressures.     

Some solutions of boundary conditions for relativistic string with massive ends

A string model of meson with massive quarks at ends is studied. As the action of the quark masses, we take (i) the length of world trajectories of the string ends (Model I), and also (ii) the integral of the geodesic curvature of world trajectories of the string ends (Model II). For these models, particular solutions of nonlinear boundary conditions are derived. For Model II the nonrelativistic limit is analysed.     

自旋波共振激发的新模型

本文研究了磁性薄膜中的自旋波共振激发现象。在Portis体不均匀(Ⅵ)模型的基础上,提出了非对称体不均匀(AⅥ)模型和表面-体不均匀(s-Ⅵ)模型,很好地解释了实验研究中所观察到的线性自旋波谱,在这些谱中偶奇次模被同时激发,其强度按各自不同的包络线变化。 关键词：     

Monte-Carlo Generator of Heavy Ion Collisions DCM-SMM

Physics of Particles and Nuclei Letters - The new monte-carlo generator of heavy ion collisions, DCM-SMM, based on Dubna Cascade Model (DCM-QGSM) and Statistical Multifragmentation Model (SMM) is...     

Pair production of Two Higgs Doublet Model light Higgs bosons in γγ collisions

We study the production of a pair of light, neutral, CP-even Higgs bosons in photon–photon collisions within the general Two Higgs Doublet Model (THDM). This is a process for which the lowest order contribution in both, the Standard Model and the THDM, appears at one loop. We find that the cross section for this process can be much larger in the THDM than in the Standard Model and the number of events expected at the Photon Collider will allow a determination of some of the parameters in the scalar potential.     

K介子稀有衰变及其对Multiscale WalkingTechnicolor模型的限制

在多标度人工色模型框架下计算了荷电PG玻色子     

Measurement of the Coupling Constant of the Higgs Boson with a tt ¯ $$ \overline{tt} $$ Heavy Quark Pair

Russian Physics Journal - The process of production of a Higgs boson HSM of the Standard Model (the H , h , and A bosons of the Minimal Supersymmetric Standard Model) and a $$ \overline{tt} $$...     

Some Remarks on the Higgs Mechanism

We show that at least one of the auxiliary one-component fields in the Higgs Model – the field ϕ – is not a Lorentz scalar and that it is probably not local with respect to the current. Our conclusion is that we cannot prescribe to the field ϕ a direct physical meaning. In case ϕ is not local with respect to the current it is likely that the zero eigenvalue of the mass operator does not appear in the theory at all. In case ϕ is quasilocal with respect to j₀, such an eigenvalue appears at least in the original Model and the mass spectrum can be different for different versions of the Model. We conjecture that this can be explained with help of the theory of unitarily inequivalent representations. We display the difficulty in translating into the quantal language the classical procedure leading from the original Model to the variant of unitary gauge. We hope that with help of unitarily inequivalent representations this difficulty can be resolved. We exhibit the fact that in the Higgs Model the whole gauge group does not have a direct physical meaning, in contradistinction to electrodynamics, where the local gauge group only has no physical significance.     

A mathematical reformulation of Derrida's REM and GREM

The large system limit of the Random Energy Model (REM) and generalized Random Energy Model (GREM) of Derrida is investigated, and found to be universal. This permits systematic calculations of relevance in particular to Parisi's solution of the Sherrington-Kirkpatrick spin-glass model.     

模型飞行验证系统测控与信息传输技术研究

模型飞行验证系统是为更加有效地开展模型自由飞试验研究而设计的通用试验系统,测控(TT C)与信息传输系统是其信息保障的核心。本文在充分考虑模型自由飞试验特点的基础上,重点研究了模型飞行验证系统研制过程中的测控与信息传输技术,介绍了其工作原理及实现方法,并对部分结果进行分析。     

Chemisorption of 4-(4-amino-phenylazo) benzoic acid molecule on the Si(0 0 1)-(4 × 2) surface

Structural and electronic properties of self-assembled monolayer with 4-(4-amino-phenylazo) benzoic acid (APABA) on the Si(0 0 1)-(4 × 2) surface are investigated by ab initio calculation based on density functional theory. For the APABA chemisorption on the silicon surface, we have assumed two different binding sites: (i) amino group of molecule and (ii) carboxyl group of molecule. Considering amino-site, we have assumed two possible models for the chemisorption of molecules on the Si(0 0 1)-(4 × 2) surface: (i) an intrarow position between two neighboring Si dimers in the same dimer row (Model I), (ii) on-dimer position (Model II). We have found that Model II is 1.10 eV energetically more favorable than Model I. The Si-N bond length was calculated as 1.85 Å which is in excellent agreement with the sum of the corresponding covalent radii of 1.87 Å. Considering carboxyl-site, we have assumed exactly the same model as mentioned above. Again we have found that Model II is energetically favorable than Model I. The calculated bond lengths for Si-O and O-C are 1.76 and 1.35 Å, respectively.     

Correspondances between the Symmetric Lund Model and the Dual Resonance Model

The Symmetric Lund Model is formulated in a manifestly forward-backward symmetric way and generalized to include transverse momenta and finite width resonances. It is shown to possess multiregge behaviour and inclusive-exclusive connection. It's characteristic exp (?area) damping factor is shown to occur also in dual amplitudes, if the Regge slope is given an imaginary part. The introduction of an infinite family of resonances described by a continuous mass spectrum is advocated; it realizes the synthesis of the Symmetric Lund Model with the Bowler and the Artru-Mennessier models, and improves the connection with the Dual Resonance Model.     

Determination of surface tension of liquid ternary Ni–Cu–Fe and sub-binary alloys

Experimental data in the literature are almost limited to determine the thermophysical properties of multicomponent complex alloys, especially due to the inability of laboratories to achieve the desired ideal conditions, due to the difficulty of protection from oxidation at high temperatures and other contamination at high temperatures, due to time and cost in laboratory studies. Due to these reasons, the theoretical data obtained in this subject is of great importance. In this study, a series of geometric and physical models, such as Chou’s general solution model (GSM), Muggianu’s Model, Kohler’s Model, Toop’s Model, Hillert’s Model, Guggenheim’s Model, Butler’s Model, Egry’s Model and ideal solution model for quasi-binary alloy system for Section A: Ni_{0.4(1 – x)}Cu_xFe_{0.6(1 – x)}. and Section B: (Ni_xCu_0.2Fe_{0.8 – x}) are used to calculate the surface tension-composition and surface tension-temperature curves of the Cu-Fe-Ni ternary liquid system are plotted. The data for this process is evaluated by means of an extended Redlich-Kister-Muggianu polynomial fit to the experimental values of the surface tensions of the binary liquid alloy systems. The obtained results for these models are also compared with the available data in the literature and relatively good agreements are observed. In addition, the surface segregation having important key factor in determining surface tension of the liquid alloy Ni-Fe-Cu has also been investigated in this work.     

Secluded WIMP dark matter

We consider a generic mechanism via which thermal relic WIMP dark matter may be decoupled from the Standard Model, namely through a combination of WIMP annihilation to metastable mediators with subsequent delayed decay to Standard Model states. We illustrate this with explicit examples of WIMPs connected to the Standard Model by metastable bosons or fermions. In all models, provided the WIMP mass is greater than that of the mediator, it can be secluded from the Standard Model with an extremely small elastic scattering cross-section on nuclei and rate for direct collider production. In contrast, indirect signatures from WIMP annihilation are consistent with a weak scale cross-section and provide potentially observable γ-ray signals. We also point out that γ-ray constraints and flavor physics impose severe restrictions on MeV-scale variants of secluded models, and identify limited classes that pass all the observational constraints.     

The probable fate of the Standard Model

Extrapolating the Standard Model to high scales using the renormalisation group, three possibilities arise, depending on the mass of the Higgs boson: if the Higgs mass is large enough the Higgs self-coupling may blow up, entailing some new non-perturbative dynamics; if the Higgs mass is small the effective potential of the Standard Model may reveal an instability; or the Standard Model may survive all the way to the Planck scale for an intermediate range of Higgs masses. This latter case does not necessarily require stability at all times, but includes the possibility of a metastable vacuum which has not yet decayed. We evaluate the relative likelihoods of these possibilities, on the basis of a global fit to the Standard Model made using the Gfitter package. This uses the information about the Higgs mass available directly from Higgs searches at LEP and now the Tevatron, and indirectly from precision electroweak data. We find that the ‘blow-up’ scenario is disfavoured at the 99% confidence level (96% without the Tevatron exclusion), whereas the ‘survival’ and possible ‘metastable’ scenarios remain plausible. A future measurement of the mass of the Higgs boson could reveal the fate of the Standard Model.     

Triaxiality andγ-softness in196Pt

The nuclear level structure and electromagnetic properties of¹⁹⁶Pt were investigated withγ-spectroscopic techniques using multiple Coulomb excitation by²⁰⁸Pb projectiles. Particle-γ, and particle-γ-γ coincidences were measured over a wide range of scattering angles.E2-transition moments and static quadrupole moments have been determined by a comparison of experimental scattering-angle dependentγ yields with calculated yields in a largely model-independent procedure. The results are compared with different theoretical models: the Asymmetric-Rotor Model, the Generalized Collective Model, and the Interacting Boson Model. The best agreement is obtained with the Generalized Collective Model representing a triaxial nucleus which is soft in theγ degree of freedom.     

Muon g-2 discrepancy： new physics or a relatively light Higgs？

After a brief review of the muon g-2 status, we discuss hypothetical errors in the Standard Model prediction that might explain the present discrepancy with the experimental value. None of them seems likely. In particular, a hypothetical increase of the hadroproduction cross section in low-energy e^＋e^- collisions could bridge the muon g-2 discrepancy, but it is shown to be unlikely in view of current experimental error estimates. If, nonetheless, this turns out to be the explanation of the discrepancy, then the 95% CL upper bound on the Higgs boson mass is reduced to about 135 GeV which, in conjunction with the experimental 114.4 GeV 95% CL lower bound, leaves a narrow window for the mass of this fundamental particle.     

Enhanced di-photon Higgs signal in the Next-to-Minimal Supersymmetric Standard Model

In the Next-to-Minimal Supersymmetric Standard Model, CP-even Higgs bosons can have masses in the range of 80–110 GeV in agreement with constraints from LEP due to their sizeable singlet component. Nevertheless their branching ratio into two photons can be more than 10 times larger than the one of a Standard Model Higgs boson of similar mass due to a reduced coupling to b quarks. This can lead to a spectacular enhancement of the Higgs signal rate in the di-photon channel at hadron colliders by a factor 6. Corresponding scenarios can occur in the Next-to-Minimal Supersymmetric Standard Model for a relatively low Susy breaking scale.