The associated production of Z boson and a pair of new quarks at the Large Hadron Collider （LHC） is studied. The cross sections for both sequential fermions and vector-like fermions are presented. It is found that f...The associated production of Z boson and a pair of new quarks at the Large Hadron Collider （LHC） is studied. The cross sections for both sequential fermions and vector-like fermions are presented. It is found that for sequential fermions the cross sections can reach 1 - 10^2 /b for heavy quark mass mQ from 1000 GeV to 200 GeV. For vector-like quarks, the cross sections are suppressed by mixing parameter sin OL. Focusing on process pp → b＇b＇, we investigate the possibility of detecting the 6l 4- 2j signal. For a b＇ with light mass and a large branching ratio of b＇ → bZ, it is found that only several signal events （ parton level ） can be produced with 1000 fb^-1 integrated luminosity. Although the signal events are rare, all the final states are produced centrally and multi lepton final states are clear at hadron collider, which could be easily detected.展开更多
We study prompt hadroproduction of the charged bottomonium-like states Zb± （10610） and Zb±（10650）, and the charged eharmonium-like states Zc± （3900） and Zc± （4020）, at the Tevatron and the ...We study prompt hadroproduction of the charged bottomonium-like states Zb± （10610） and Zb±（10650）, and the charged eharmonium-like states Zc± （3900） and Zc± （4020）, at the Tevatron and the LHC, provided that these states are S-wave hadronic molecules. Using two Monte Carlo event generators, Herwig and Pythia, to simulate the production of heavy meson pairs, we derive an order-of-magnitude estimate of the production rates for these four particles. Our estimates yield a cross section at the nb level for the Zb（10610） and Zb（10650）. The results for the Zc（3900） and Zc （4020） are larger by a factor of 2~30. These cross sections are large enough to be observed, and measurements at hadron colliders in the future will supplement the study using electron-positron collisions, and therefore allow to explore the mysterious nature of these exotic states.展开更多
We study the centrality dependence of the mid-rapidity （｜y｜ 〈 0.5） yields and transverse momentum distributions of K＊ （892）° and φ（1020） resonances produced in Pb ＋ Pb collisions at SNN= 2.76 TeV. The...We study the centrality dependence of the mid-rapidity （｜y｜ 〈 0.5） yields and transverse momentum distributions of K＊ （892）° and φ（1020） resonances produced in Pb ＋ Pb collisions at SNN= 2.76 TeV. The mid- rapidity density （dN/dy） and the shape of the transverse momentum spectra are well reproduced by an earlier proposed Unified Statistical Thermal Freeze-out Model （USTFM）, which incorporates the effects of both longitudinal as well as transverse hydrodynamic flow. The freeze-out properties in terms of kinetic freeze-out temperature and transverse flow velocity parameter are extracted from the model fits to the transverse momentum data provided by the ALICE experiment at the LHC. The kinetic freeze-out temperature is found to increase with decreasing event centrality while the transverse flow velocity parameter shows a mild decrease on moving towards peripheral collisions. Moreover the centrality dependence of the mid-rapidity system size at freeze-out has also been studied in terms of transverse radius parameter.展开更多
We perform a comparative study for the LHC di-photon Higgs signal in three different littlest Higgs models with T-parity (named LHT-Ⅰ, LHT-Ⅱ and LHT-Ⅲ). We find that compared with the Standard Model prediction, the...We perform a comparative study for the LHC di-photon Higgs signal in three different littlest Higgs models with T-parity (named LHT-Ⅰ, LHT-Ⅱ and LHT-Ⅲ). We find that compared with the Standard Model prediction, the di-photon rate is always suppressed and the suppression extent can be different for different models. The LHC will soon give a solid judgement whether the di-photon rate is larger than the SM prediction, which can be utilized as a sensitive probe for the three models.展开更多
In the simplest little Higgs model （SLH）, we study the spin correlations in the top quark pair production at the LHC and ILC. We find that the SLH always suppresses the tt spin correlations compared to the SM values...In the simplest little Higgs model （SLH）, we study the spin correlations in the top quark pair production at the LHC and ILC. We find that the SLH always suppresses the tt spin correlations compared to the SM values. At the LHC, the suppression can be over 10% for mz, 〈 750 GeV. The SLH prediction value is outside the 1σ range of the experimental data from ATLAS, and within 1σ range of the experimental data from CMS. At the ILC, the SLH can sizably suppress the tt spin correlation for mz, approaching the center-of-mass energy √s. For example, the maximal suppression can reach -22.5%, -14.5%, and -9.5% for √s = 500 Ge V, 800 Ge V, and 1000 GeV, respectively. Therefore, the tt spin correlation at the ILC can be a sensitive probe for the SLH.展开更多
In this paper, we study the single neutral top-higgs （h0） production processes at the CERN Large Hadron Collider （LHC） and the International Linear Collider （ILC）. At the LHC, the production rates of processes ...In this paper, we study the single neutral top-higgs （h0） 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）h0 are too small to detect ht0. However, with the reasonable parameter values, the cross sections can reach the level of 102 fb for qq→qqh0process and 103 fb for top quark associated production process pp → th0 ＋ X, respectively. At the ILC, we study the single top-higgs production processes e-y → veW-h0 and yy → W＋W-h0 in e-y and yy collisions. It is found that the production cross sections can reach the level of a few t-b with reasonable parameter values. Furthermore, such processes with the flavor-changing decay mode h0 tO 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.展开更多
基金Supported in part by the National Science Foundation of China under Grant Nos.90503002 and 10821504by the National Basic Research Program of China under Grant No.2010CB833000
文摘The associated production of Z boson and a pair of new quarks at the Large Hadron Collider （LHC） is studied. The cross sections for both sequential fermions and vector-like fermions are presented. It is found that for sequential fermions the cross sections can reach 1 - 10^2 /b for heavy quark mass mQ from 1000 GeV to 200 GeV. For vector-like quarks, the cross sections are suppressed by mixing parameter sin OL. Focusing on process pp → b＇b＇, we investigate the possibility of detecting the 6l 4- 2j signal. For a b＇ with light mass and a large branching ratio of b＇ → bZ, it is found that only several signal events （ parton level ） can be produced with 1000 fb^-1 integrated luminosity. Although the signal events are rare, all the final states are produced centrally and multi lepton final states are clear at hadron collider, which could be easily detected.
基金Supported in part by the DFG and the NSFC through funds provided to the Sino-German CRC 110 ＂Symmetries and the Emergence of Structure in QCD＂, and by the NSFC under Grant No. 11165005
文摘We study prompt hadroproduction of the charged bottomonium-like states Zb± （10610） and Zb±（10650）, and the charged eharmonium-like states Zc± （3900） and Zc± （4020）, at the Tevatron and the LHC, provided that these states are S-wave hadronic molecules. Using two Monte Carlo event generators, Herwig and Pythia, to simulate the production of heavy meson pairs, we derive an order-of-magnitude estimate of the production rates for these four particles. Our estimates yield a cross section at the nb level for the Zb（10610） and Zb（10650）. The results for the Zc（3900） and Zc （4020） are larger by a factor of 2~30. These cross sections are large enough to be observed, and measurements at hadron colliders in the future will supplement the study using electron-positron collisions, and therefore allow to explore the mysterious nature of these exotic states.
基金Supported by Council of Scientific and Industrial Research,New Delhi for This Work
文摘We study the centrality dependence of the mid-rapidity （｜y｜ 〈 0.5） yields and transverse momentum distributions of K＊ （892）° and φ（1020） resonances produced in Pb ＋ Pb collisions at SNN= 2.76 TeV. The mid- rapidity density （dN/dy） and the shape of the transverse momentum spectra are well reproduced by an earlier proposed Unified Statistical Thermal Freeze-out Model （USTFM）, which incorporates the effects of both longitudinal as well as transverse hydrodynamic flow. The freeze-out properties in terms of kinetic freeze-out temperature and transverse flow velocity parameter are extracted from the model fits to the transverse momentum data provided by the ALICE experiment at the LHC. The kinetic freeze-out temperature is found to increase with decreasing event centrality while the transverse flow velocity parameter shows a mild decrease on moving towards peripheral collisions. Moreover the centrality dependence of the mid-rapidity system size at freeze-out has also been studied in terms of transverse radius parameter.
基金supported by the National Natural Science Foundation of China (Grant Nos. 11105116 and 11005089)
文摘We perform a comparative study for the LHC di-photon Higgs signal in three different littlest Higgs models with T-parity (named LHT-Ⅰ, LHT-Ⅱ and LHT-Ⅲ). We find that compared with the Standard Model prediction, the di-photon rate is always suppressed and the suppression extent can be different for different models. The LHC will soon give a solid judgement whether the di-photon rate is larger than the SM prediction, which can be utilized as a sensitive probe for the three models.
基金Supported by the National Natural Science Foundation of China under Grant Nos.11005089 and 11105116
文摘In the simplest little Higgs model （SLH）, we study the spin correlations in the top quark pair production at the LHC and ILC. We find that the SLH always suppresses the tt spin correlations compared to the SM values. At the LHC, the suppression can be over 10% for mz, 〈 750 GeV. The SLH prediction value is outside the 1σ range of the experimental data from ATLAS, and within 1σ range of the experimental data from CMS. At the ILC, the SLH can sizably suppress the tt spin correlation for mz, approaching the center-of-mass energy √s. For example, the maximal suppression can reach -22.5%, -14.5%, and -9.5% for √s = 500 Ge V, 800 Ge V, and 1000 GeV, respectively. Therefore, the tt spin correlation at the ILC can be a sensitive probe for the SLH.
基金supported by the National Natural Science Foundation of China (Grant No.11147193)
文摘In this paper, we study the single neutral top-higgs （h0） 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）h0 are too small to detect ht0. However, with the reasonable parameter values, the cross sections can reach the level of 102 fb for qq→qqh0process and 103 fb for top quark associated production process pp → th0 ＋ X, respectively. At the ILC, we study the single top-higgs production processes e-y → veW-h0 and yy → W＋W-h0 in e-y and yy collisions. It is found that the production cross sections can reach the level of a few t-b with reasonable parameter values. Furthermore, such processes with the flavor-changing decay mode h0 tO 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.
