Top—Higgs and the Process e^＋e^— → vvtt

We discuss the contributions of the top-Higgs ht^0 proedicted by topcolor-assisted technicolor (TC2) models to the process e^ e^-→vvtt.We find that the contributions are very large.For mht=400 GeV and ε=0.01,the production cross section of this process can reach 11.2fb,which may be detected in the future high energy e^ e^- collider experiments.The process e^ e^-→vvtt can be used to test experimentally the signal of TC2 models.     

Associated production of a neutral top-Higgs with a heavy-quark pair in the γγ collisions at ILC

We have studied the associated production processes of a neutral top-Higgs in the topcolor assisted technicolor model with a pair of heavy quarks in γγ collisions at the International Linear Collider (ILC). We find that the cross section for ttht in γγ collisions is at the level of a few fb with the c.m. energy √s=1000 GeV, which is consistent with the results of the cross section of ttH in the standard model and the cross section of tth in the minimal supersymmetric standard model. It should be clear that hundreds of to thousands of ht per year can be produced at the ILC. This process of γγ→ttht is really interesting in testing the standard model and searching the signs of technicolor.     

Associated production of a neutral top-Higgs with a heavy-quark pair in the γγ collisions at ILC

We have studied the associated production processes of a neutral top-Higgs in the topcolor assisted technicolor model with a pair of heavy quarks in γγ collisions at the International Linear Collider （ILC）. We find that the cross section for ttht in γγ collisions is at the level of a few fb with the c.m. energy √s=1000 GeV, which is consistent with the results of the cross section of ttH in the standard model and the cross section of tth in the minimal supersymmetric standard model. It should be clear that hundreds of to thousands of ht per year can be produced at the ILC. This process of γγ→ttht is really interesting in testing the standard model and searching the signs of technicolor.     

Production of Top-Pions Associated with W Boson at Next Generation γγ Colliders

In the context of topcolor-assisted technicolor （TC2） model, we study the charged and neutral top-pions production process γγ →W＋ ∏t-∏t^0. We find that the production cross section is larger than that of the process γγ→ W＋ H-H in the minimal supersymmetric standard model. With reasonable values of the parameters in the TC2 model, the cross section can reach the level of a few fb. Furthermore, the flavor-changing （FC） decay mode ∏t^0 → te^- is the best channel to detect the neutral top-pion due to the clean SM background. With a large number of events and the clean background, the neutral top-pion should be observable at future linear colliders operating in γγ mode at the TeV energy scale.     

Top Quark Decay t → cb-↑b in Topcolor-Assisted Technicolor Models

The topcolor-assisted technicolor （TC2） model predicts the existence of the top-pions and the CP-even top-Higgs with large flavor-changing couplings to the top quark, which at tree-level can mediate the top quark three-body decay t → cb-↑b. We study this decay, show the dependence of the decay rate on the relevant TC2 parameters and compare the results with the predictions in the minimal supersymmetric model. We find that the decay rate in the TC2 model is much larger than that in the minimal supersymmetric model if the new particles are not too heavy. However, in consideration of the ODF and the LEP experiment limits, the top-pion mass is greater than 340 GeV in a more realistic parameter space, so the decay width of the channel t → cb-↑b intermediated by top-pions will be depressed greatly and difficult to be detected at the future collider. Thus, to observe this channel at the future collider, considering the top-higgs contribution may be the possible way when the masses of the top-pions and the top-higgs are not degenerate.     

Searching for Flavor-Changing Neutral-Current Signals via e＋e-（γγ） →tcht0 in Topcolor-Assisted Technicolor Model

In the context of the top-color-assisted technicolor （TC2） model, the flavor-changing neutral-current （FCNC） interaction induced by the top-higgs （hOt） are predicted at tree level. We study the relevant processes of e＋e-（γγ）→tcht0 at the International Linear Collider （ILC）. It is found that these rare processes production rates can be enhanced significantly in the TC2 model. Especially for the process γγ→tcht0, the total cross section will reach a few fb in the reasonable parameter space. We also calculate the distributions of transverse momenta, pseudo-rapid and invariant mass of the top-higgs. In view of the main decay modes of top-higgs for mho 〈 2mr, we find that there will be several hundreds FCNC events produced at the ILC with annually integral luminosity of 500 fb-1. Due to the clean background, such FCNC signals can possibly be detected at the ILC.     

NLO Corrections of HTC∏^0 and ∏＋∏- Pair Production at ILC in TC2 Model

As well known, if the Higgs boson were not observed at LHC, the technicolor model would be the most favorable candidate responsible for the symmetry breaking. To overcome some defects in the previous model, some extended versions have been proposed. In the TC2 model typical signature is existence of heavy HTC and technipion ∏. A direct proof of validity of the model is to produce them at accelerator. Thus we study the production rates of e＋e^- → HTC∏^0 and e＋e^- → ∏＋∏- at ILC in the topcolor-assisted technicolor （TC2） model. In fact, there is a flood of models belonging to new physics, which can result in products with characteristics similar to HTC ＋ ∏ of the TC2 model. Therefore to distinguish this model from others one may need to investigate some details by calculating the cross section to NLO. We indeed find that the NLO corrections are significant, namely the ratio δ ≡（ σNLO - σLO）/σLO in e＋e- →HTC∏^0 exceeds 100% within a plausible parameter space.     

The single neutral top-higgs production at LHC and ILC in the Topcolor-Assisted Technicolor Model

In this paper, we study the single neutral top-higgs (h0t) production processes at the CERN Large Hadron Collider (LHC) and the International Linear Collider (ILC). At the LHC, the production rates of processes pp→Z(W)h0t are too small to detect h0t . However, with the reasonable parameter values, the cross sections can reach the level of 102 fb for qq→qqh0t process and 103 fb for top quark associated production process pp→th0t+X, respectively. At the ILC, we study the single top-higgs production processes e-γ→νeW-h0t and γγ→W+W-h0t in e-γ and γγ collisions. It is found that the production cross sections can reach the level of a few fb with reasonable parameter values. Furthermore, such processes with the flavor-changing decay mode h0t→tc might provide typical signatures to detected the top-higgs. Therefore, it is hopeful to find the signal of top-higgs at the LHC and ILC experiments via theses processes and test the TC2 model directly.     

Lepton-Flavor Violating Processes li → ljγ in Topcolor-Assisted Technicolor Models

We consider the lepton-flavor violating (LFV) processes li → ljγ in the framework of topcolor-assistedtechnicolor (TC2) models. We find that the new gauge boson Z‘ predicted by TC2 models can give significantlycontributions to these processes via the flavor-changing couplings Z‘lilj. The present experimental bound on the LFVprocess μ→ eγ gives severe constraints on the TC2 models. Using other experimental constraints on the Z‘ mass Mz,we obtain constraints on the lepton mixing factors KTμ and KTe. The future LFV experiments will probe into TC2models.     

Probing the Lightest New Gauge Boson BH in the Littlest Higgs Model via Processes γγ→ ff^- Bg at ILC

The neutral gauge boson BH with the mass of hundreds GeV is the lightest particle predicted by the littlest Higgs （LH） model, and such particle should be the first signal of the LH model at the planed ILC if it exists indeed. In this paper, we study some processes of the BH production associated with the fermion pair at the ILC, i.e., γγ→ ff^- BH. The studies show that the most promising processes to detect BH amongγγ→ ff^- BH are γγ→ l＇^＋l＇^-BH （l＇ = e,μ）, and they can produce the sufficient signals in most parameter space preferred by the electroweak precision data at the ILC. On the other hand, the signal produced via the certain BH decay modes is typical and such signal can be easily identified from the SM background. Therefore, BH, the lightest gauge boson in the LH model, would be detectable at the photon collider realized at the ILC.     

Single Chargino Production with R-Parity Lepton Number Violation in Photon-Photon Collisions

We examine the process γγ→ x - at photon-photon collider in the minimal supersymmetric standard model with R-parity violation,where all the one-loop diagrams are considered.We mainly discuss the effects of bilinear breaking terms,and conclude that their contributions may be important compared with trilinear terms.Our results show that the events of this process could be detectable at photon-photon colliders,if the values of the parameters are favorable.``     

Study of K~*(892)~0 and ?(1020) meson production in proton–proton and Pb–Pb collisions at ■=2.76 TeV

In this paper, we describe a study of charged particle yield as a function of pTfor K~*(892)~0 and ?(1020) mesons in proton–proton(pp) and Pb–Pb collisions at ■=?2.76 Te V in the central rapidity region of |y|0.5, in a pTrange of ?pT15 Ge V c~(-1) in pp collisions and in a pT range of 0??pT??20 Ge V c~(-1) in Pb-Pb collisions. We also investigated a very important ratio,the nuclear modification factor, to study the effects of the medium in the most central region, i.e.0%–5% centrality. For data simulation, we used the EPOS-LHC and EPOS-1.99 models. To check the validity of these models' simulations, we compared the data obtained from these Monte Carlo simulation programs with ALICE experimental data for ■=?2.76 Te V. It was concluded that the models' predictions for the ?-meson in pp and for the most central Pb-Pb collisions disagreed with the ALICE data, and that the difference increased with pT. This may be connected with the essential role of collective parton behaviors which could not have been taken into account by the models. For K~(*0) mesons, both programs gave almost the same predictions,and with pTin the interval pT??3 Ge V c~(-1), the predictions were very close to the experimental data. Both models gave higher predictions for the soft pTinterval and lower predictions for the hard interactions. The values of the RAAdistributions were lower than unity and both models were very close to the ALICE data. It is very interesting that the models were not able to describe the pTdistributions, but they gave good predictions for their ratios. This may possibly be due to parton collective behaviors. We observed some additional suppression of K~(*0) at low values of pT with respect to f-mesons, which may be related to the role of the masses of the particles in soft interactions. The rising trend for R_(AA) in the region from pT=?10 Ge V c~(-1) to 20 Ge V c~(-1) observed by the ALICE experiment was absent for the f-mesons.     

The lepton flavor violating signal of the extra gauge boson Z′in photon-photon collision at the ILC

The hitherto unconstrained lepton flavor mixings,induced by the new gauge boson Z ,which are the prediction of many new physics models,such as topcolor-assisted technicolor (TC2) models and flavor-universal TC2 models,may lead to the lepton flavor violating productions of τμˉ,τeˉ and μeˉ in photon-photon collision at the proposed International Linear Collider (ILC).Through a comparative analysis of these processes,we find that the better channel to probe the new physics models is the production of τμˉ or τeˉ which occurs at a much higher rate than μeˉ production due to the large mixing angle and the large flavor changing coupling,and may reach the detectable level of the ILC for a large part of the parameter space.Since the rates predicted by the Standard Model are far below the detectable level,these processes may serve as a sensitive probe for such new physics models.     

Correction of the Littlest Higgs Model to Higgs Production Process e-γ→veW-H in e-γ Collisions

The littlest Higgs model is the most economical one among various little Higgs models. In the context of the littlest Higgs （LH） model, we study the process e-γ → veW^-H and calculate the contributions of the LH model to the cross section of this process. The results show that in most of the parameter spaces preferred by the electroweak precision data, the value of the relative correction is larger than 10%. Such correction to the process e-γ →veW^-H is large enough to be detected via e-γ collisions in the future high energy linear e^＋ e^- collider （ILC） experiment with the c.m. energy √s = 500 GeV and a yearly integrated luminosity ￡ = 100fb^-1, which will give an idea/way to test the model.     

Complementary studies on N＊ from e＋e-, pp and pp collisions

Complementary to the conventional experimental studies on N＊ from πN and γ（＊）N reactions, the e＋e-, pp and pp collisions can give novel insights into these N＊ resonances. While the e＋e- collisions through production and decay of vector charmonium ψ provide a nice isospin filter for a simultaneously study of N＊, △＊, ∧＊, ∑＊ and 2＊, the pp collisions should be the best place for producing those △＊＋＋ with large coupling to p＋p though pp →nA＊＋＋ reaction, and the pp collisions should be the best place for looking for those N＊ with large coupling to σN.     

Surface Emission of Quark Gluon Plasma at RHIC and LHC

Within the framework of a factorization model, we study the behaviour of nuclear modification factor in Au Au collisions at RHIC and Pb-Pb collisions at LHC. We find that the nuclear modification factor is inversely proportional to the radius of the quark-gluon plasma and is dominated by the surface emission of hard jets. We predict the nuclear modification factor R^LHC AA - 0.15 in central Pb-Pb collisions at LHC. The study shows that the factorization model can be used to describe the centrality dependence of nuclear modification factor of the high transverse momentum particles produced in heavy ion collisions at both RHIC and LHC.     

Synchronization mechanism of clapping rhythms in mutual interacting individuals

In recent years, clapping synchronization between individuals has been widely studied as one of the typical synchronization phenomena. In this paper, we aim to reveal the synchronization mechanism of clapping interactions by observing two individuals’ clapping rhythms in a series of experiments. We find that the two synchronizing clapping rhythm series exhibit long-range cross-correlations(LRCCs);that is, the interaction of clapping rhythms can be seen as a strong-anticipation process. Previous studies have demonstrated that the interactions in local timescales or global matching in statistical structures of fluctuation in long timescales can be sources of the strong-anticipation process. However, the origin of the strong anticipation process often appears elusive in many complex systems. Here, we find that the clapping synchronization process may result from the local interaction between two clapping individuals and may result from the more global coordination between two clapping individuals. We introduce two stochastic models for mutually interacting clapping individuals that generate the LRCCs and prove theoretically that the generation of clapping synchronization process needs to consider both local interaction and global matching. This study provides a statistical framework for studying the internal synchronization mechanism of other complex systems. Our theoretical model can also be applied to study the dynamics of other complex systems with the LRCCs, including finance, transportation, and climate.     

Charged Top-Pion Production Associated with a Gluon Jet at the LHC

The charged top-pions have been predicted by the topcolour-assisted technicolour （TC2） model and the observation of the charged top-pions can be regarded as the robust evidence of the model. We study the charged top-pion and gluon associated production at the LHC, i.e., pp → gIIe^＋. The cross section of this process can reach tens of pb, even hundreds ofpb, and there will be enough gIIt^＋ events produced at the LHC. Because the gIIt^＋ production is a flavour-changing （FC） process, the SM background can be greatly depressed. Furthermore, there exists an FC decay mode cb for the charged top-pions, and such decay mode can provide us with the typical signals to detect the charged top-pions. Therefore, it is hopeful to find the charged top-pions via the gIIe^＋ production at the LHC.     

System size in relativistic heavy ion collisions

System size is more than a geometrical quantity in relativistic heavy ion collisions; it is closely related to evolution process, i.e. a different system size corresponds to a different evolution process, and whether QGP is produced depends on the system size. We propose that the system size should be under the same level when comparing the measurements from different colliding nuclei. The equivalence of the peripheral collisions of Au-Au and the central collisions of smaller nuclei is studied using the Monte Carlo method. Comparing the transverse overlapping area of the colliding nuclei, the number of participant nucleons and the number of nucleon-nucleon binary collisions in various colliding nuclei, we give an estimate of the correspondence in system size. This is helpful in the experimental comparison of the measurements from different colliding nuclei.     

Roles of N?→NN and πN→? Reactions in Heavy-Ion Collisions at Intermediate Energies

Within the framework of the isospin-dependent transport model, the roles of the reactions N? → NN and πN→ ? are investigated through simulating heavy-ion collisions at 1000 MeV/nucleon. The absorption process N? → NN plays an important role for heavy impact systems and small impact parameters than for light impact systems and large impact parameters. The resorption process πN→ ? is of importance for heavy impact systems and large impact parameters than for light impact systems and small impact parameters. Thus the influences of the reaction N? → N N(πN→ ?) on pion production dynamics can be neglected in heavy-ion collisions for smaller(larger) impact parameters and light systems. It is the reaction πN→ ? that causes the anti-correlation of pions and nucleons in the rapidity dependence of the directed flow.