Probing the scale of new physics in the ZZγ coupling at e~+e~- colliders

The Z Zγtriple neutral gauge couplings are absent in the Standard Model(SM)at the tree level.They receive no contributions from dimension-6 effective operators,but can arise from effective operators of dimension-8.We study the scale of new physics associated with such dimension-8 operators that can be probed by measuring the reaction e~+e~-→Zγ followed by ■ decays,at future e~+e~- colliders including the CEPC,FCC-ee,ILC and CLIC.We demonstrate how angular distributions of the final-state mono-photon and leptons can play a key r?le in suppressing SM backgrounds.We further demonstrate that using electron/positron beam polarizations can significantly improve the signal sensitivities.We find that the dimension-8 new physics scale can be probed up to the multiTeV region at such lepton colliders.     

Probing the photon at γe-colliders

We investigate the feasibility of studying the photon structure function at a e-collider. We show that the deep inelastic probe of the real photon by a highly virtual photon in such a collider will extend significantly thex andQ ² range presently accessible ate ⁺ e ^– colliders. In addition, we study the production of large transverse momentum dijet final states to determine the sensitivity of these cross sections to different parametrisations of the quark and gluon distributions in the photon.     

Probing the CP violating Hγγ coupling using interferometry

The diphoton invariant mass distribution from the interference between gg→H→γγ and gg→γγ is almost antisymmetric around the Higgs mass MH.We propose a new observable Aint,the ratio of the sign-reversed integral around MH(e.g.■)and the cross-section of the Higgs signal,to quantify this effect.We study Aint both in the Standard Model(SM)and new physics with various CP violating Hγγ couplings.Aint in SM could reach a value of 10%,while for CP violating Hyy coupling Aint could range from 10% to-10%,which could probably be detected in the HL-LHC experiments.Aint with both CP violating Hγγ and Hgg couplings is also studied,and its range of values is found to be slightly larger.     

Investigation of coupling effect on the evolution of Richtmyer-Meshkov instability at double heavy square bubbles

This study investigates numerically the coupling effect on the evolution of Richtmyer-Meshkov instability at double heavy square bubbles. Five scenarios are considered, each with varying initial separations S/L(where L demotes the side length of the square)ranging from 0.125 to 1.0. Squares are filled with SF₆ gas, and are enclosed by N₂ gas. The simulations of shock-induced multispecies flow are performed by solving the two-dimensional compressible Euler equations with a h...     

Estimation of the QED coupling constant α at\sqrt s = M_Z

LEP measurements of theZ ⁰ parameters have been used to estimate the value of QED coupling constant at theZ ⁰ mass. The estimated value α _eff ^-1 (M _Z )=128.2±0.9 _-0.4 ^+0.0 (M _top) is in good agreement with the expectation of 128.0 _?0.4 ^+0.2 from the Standard Model.     

Probing the TC2 model via Production of Top Quark Pairs at Tevatron and LHC

The topcolour-assisted technicolour （TC2） model is an interesting dynamical theory among the various new physics models. We cMculate the total tt cross section and the relative correction of the TC2 model to the cross section at Tevatron Run Ⅱ and LHC. At the Tevatron Run Ⅱ, the cross section predicted by the standard model （SM） is consistent with the experimental data, and in most parameter spaces of the TC2 model, the relative correction of the TC2 model to the cross section is too small to be detectable. We find that the tt cross section is more sensitive to the parameters of the TC2 model at the LHC and the relative correction of the TC2 model to the cross section is over 10% in general. Such a value of the relative correction should be large enough to be detectable at the LHC. Therefore, it is promising to find the clue of the TC2 model via the tt production at the LHC.     

On the longitudinal electromagnetic coupling of the Δ

The relativistic corrections, corresponding to the transverse and longitudinal excitation of the Δ, are included in the original Blomqvist-Laget model. They are calibrated against the pion photoproduction data. The measurement of the transverse-longitudinal interference cross sections of the (e, e′ π⁰) reaction is the most promising way to study the longitudinal coupling of the Δ.     

Probing the Stau－Stau－Higgs Couplings in the MSSM at NLC

In the minimal supersymmetric standard model (MSSM) with CP violating phases, this paper discusses the production of the lJghtest neutral Higgs boson in association with tau sleptons at future high-energy e^ e^- linear colliders. In parameter space of the constrained MSSM, the production cross section of e^ e^→h^0T1 T1^- can be very substantial at high energies. This process would provide a production mechanism for probing couplings of neutral Higgs bosoas to tau sleptons as well as some soft supersymmetric breaking parameters at next linear colliders.     

Probing the role of metal cations on the aggregation behavior of amyloid β-peptide at a single molecule level by AFM

With the development of nanotechnology, understanding of intermolecular interactions on a single molecule level by atomic force spectroscopy (AFM) has played an important role in molecular biology and biomedical science. In recent years, some research suggested that the presence of metal cations is an important regulator in the processes of misfolding and aggregation of the amyloid β-protein (Aβ), which may be an important etiological factor of Alzheimer’s disease. However, the knowledge on the principle of interactions between Aβ and metal cations at the single molecule level is still poor understood. In this paper, the amyloid β-protein (Aβ) was fabricated on substrate of mixed thiol-modified gold nanoparticles using self-assembled monolayer method and the adhesion force in the longitudinal direction between metal cations and Aβ42 were investigated by AFM. The role of metal ions on Aβ aggregation is discussed from the perspective of single molecular force. The force results showed that the specific adhesion force F _i and the nonspecific force F ₀ between a single Aβ–Aβ pair in control experiment were calculated as 42 ± 3 and 80 pN, respectively. However, F _i between a single Aβ–Aβ pair in the presence of Cu²⁺, Zn²⁺, Ca²⁺ and Al³⁺ increased dramatically to 84 ± 6, 89 ± 3, 73 ± 5, 95 ± 5 pN successively, which indicated that unbinding between Aβ proteins is accelerated in the presence of metal cations. What is more, the imaging results showed that substoichiometric copper cations accelerate the formation of fibrils within 3 days. The combined atomic force spectroscopy and imaging analysis indicate that metal cations play a role in promoting the aggregating behavior of Aβ42.     

Probing the QCD equation of state with thermal photons in nucleus–nucleus collisions at RHIC

Thermal photon production at mid-rapidity in Au+Au reactions at is studied in the framework of a hydrodynamical model that describes efficiently the bulk identified hadron spectra at RHIC. The combined thermal plus NLO pQCD photon spectrum is in good agreement with the yields measured by the PHENIX experiment for all Au+Au centralities. Within our model, we demonstrate that the correlation of the thermal photon slopes with the charged hadron multiplicity in each centrality provides direct empirical information on the underlying degrees of freedom and on the form of the equation of state, s(T)/T³, of the strongly interacting matter produced in the course of the reaction. PACS 12.38.Mh, 24.10.Nz, 25.75.-q, 25.75.Nq     

Probing the statistics of transport in the Hénon Map

The phase space of an area-preserving map typically contains infinitely many elliptic islands embedded in a chaotic sea. Orbits near the boundary of a chaotic region have been observed to stick for long times, strongly influencing their transport properties. The boundary is composed of invariant “boundary circles.” We briefly report recent results of the distribution of rotation numbers of boundary circles for the Hénon quadratic map and show that the probability of occurrence of small integer entries of their continued fraction expansions is larger than would be expected for a number chosen at random. However, large integer entries occur with probabilities distributed proportionally to the random case. The probability distributions of ratios of fluxes through island chains is reported as well. These island chains are neighbours in the sense of the Meiss-Ott Markov-tree model. Two distinct universality families are found. The distributions of the ratio between the flux and orbital period are also presented. All of these results have implications for models of transport in mixed phase space.     

Study of spin sum rules （and the strong coupling constant at large distances）

We present recent results from Jefferson Lab on sum rules related to the spin structure of the nucleon. We then discuss how the Bjorken sum rule with its connection to the Gerasimov-Drell-Hearn sum, allows us to conveniently define an effective coupling for the strong force at all distances.     

Detection of Charged Higgs Bosons in e~+e~-(γγ)→tφ~- Production at the ILC

In the context of the left-right twin Higgs (LRTH) model,we have studied the charged Higgs bosons production processes e~+e~-(γγ)→tφ~at the International Linear Collider (ILC).It is found that the cross sections of these two processes could reach a few fb with reasonable parameter values.With the yearly integrated luminosity of L=500 fb-1 expected at the ILC,one could collect hundreds up to thousands of charged Higgs events via these two processes.Therefore,our researches in this paper can help us search for charged Higgs bosons,and furthermore,to test the LRTH model.     

Gradient models of the axion–photon coupling

We establish an extended version of the Einstein–Maxwell-axion model by introducing into the Lagrangian cross-terms, which contain the gradient four-vector of the pseudoscalar (axion) field in convolution with the Maxwell tensor. The gradient model of the axion–photon coupling is applied to cosmology: we analyze the Bianchi-I type Universe with an initial magnetic field, electric field induced by the axion–photon interaction, cosmological constant and dark matter, which is described in terms of the pseudoscalar (axion) field. Analytical, qualitative and numerical results are presented in detail for two distinguished epochs: first, for the early Universe with magnetic field domination; second, for the stage of late-time accelerated expansion.     

H→γγ: a comment on the indeterminacy of non-gauge-invariant integrals

We reanalyze the recent computation of the amplitude of the Higgs boson decay into two photons presented by Gastmans et al. [1, 2]. The reasons for why this result cannot be the correct one have been discussed in some recent papers. We address here the general issue of the indeterminacy of integrals with four-dimensional gauge-breaking regulators and to which extent it might eventually be solved by imposing physical constraints. Imposing gauge invariance as the last step upon Rξ-gauge calculations with four-dimensional gauge-breaking regulators, allows us to recover the well known H→γγ result. However we show that in the particular case of the unitary gauge, the indeterminacy cannot be tackled in the same way. The combination of the unitary gauge with a cutoff regularization scheme turns out to be non-predictive.     

Doubly heavy baryon production at γγ collider

The inclusive production of doubly heavy baryons Ξ_cc${\Xi }_{cc}$ and Ξ_bb${\Xi }_{bb}$ at γγ collider is investigated. It is found that the contribution from the heavy quark pair QQ in color triplet and color sextet are important.     

Probing anomalous top-Higgs couplings at the HL-LHC via H→WW~* decay channels

We study the prospects of probing the anomalous tHq(q=u,c)couplings via SS2L or 3L signatures at the High Luminosity(HL-LHC)run of the 14 Te V CERN collider.We focus on signals of the tH associated production followed by the decay modes t→b?~+ν_?and H→W W~*,and ■ production followed by the decay modes t→b?~+ν_?and■where?=e,μ.Based on two types of H→W W~*decay topologies,one assuming the semileptonic decay mode H→W W~*→?~+νjj and the other the fully leptonic decay mode■,we perform a full simulation for signals and backgrounds.It is shown that,at the future HL-LHC,the branching ratio Br(t→uh)(Br(t→ch))can be probed to 1.17(1.56)×10~(-3)for the same-sign di-lepton channel,and to7.1×10~(-4)(1.39×10~(-3))for the 3L channel at 3σsensitivity.