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 gammagamma collisions at the International Linear Collider (ILC). We find that the cross section for tbar{t}h_t in gammagamma collisions is at the level of a few fb with the c.m. energy sqrt{s}=1000 GeV, which is consistent with the results of the cross section of tbar{t}H in the standard model and the cross section of tbar{t}h in the minimal supersymmetric standard modeland the little Higgs models. It should be distinct that hundreds of to thousands of h_t per year can be produced at the ILC, this process of gammagamma to tbar{t}h_t is really interesting in testing the standard model and searching the signs of technicolor.
We study the pair production of scalar top quarks in e+e- collisions with the subsequent decay of the top squarks into b-quarks and charginos. We simulate this process using PYTHIA6.4 for beam energies 2E_beam = 350, 400, 500, 800, 1000 GeV. Proposing a set of criteria we obtain a good separation of the signal stop events from top quark pair production which is the main background. The number of stop production events obtained with the proposed cuts for different energies is calculated for an integrated luminosity of 1000 1/fb. We propose a method to reconstruct the mass of the top squark, provided the mass of the lightest neutralino is known, and estimate the error of the mass determination for the case sqrt{s} = 500 GeV.
In this work, we investigate the prompt $J/psi$ production in associated with top quark pair to leading order in the nonrelativistic QCD factorization formalism at the LHC with $sqrt{s} =13$ TeV. In addition to the contribution from direct $J/psi$ production, we also include the indirect contribution from the directly produced heavier charmmonia $chi_{cJ}$ and $psi^prime$. We present the numerical results for the total and differential cross sections and find that the $sideset{^3}{^{(8)}_1}{mathop{{S}}}$ states give the dominant contributions. The prompt $tbar t J/psi$ signatures at the LHC are analyzed in the tetralepton channel $ppto (tto W^+(ell^+ u)b) (bar t to W^-(ell^- bar u)bar b) (J/psitomu^+mu^-)$ and trilepton channel $ppto (tto W(q q^prime)b) ( t to W(ell u) b) (J/psitomu^+mu^-)$, with the $J/psi$ mesons decaying into muon pair, and the top quarks decaying leptonically or hadronically. We find that $tbar t J/psi$ proudction can be potentially detected at the LHC, whose measurement is useful to test the heavy quarkonium production mechanism.
We consider soft gluon emission corrections to the production of a top-antitop pair in association with a Higgs boson at hadron colliders. In particular, we present a soft-gluon resummation formula for this production process and gather all elements needed to evaluate it at next-to-next-to-leading logarithmic order. We employ these results to obtain approximate next-to-next-to-leading order (NNLO) formulas, and implement them in a bespoke parton-level Monte Carlo program which can be used to calculate the total cross section along with arbitrary differential distributions. We use this tool to study the phenomenological impact of the approximate NNLO corrections, finding that they increase the total cross section and the differential distributions which we evaluated in this work.
We study pair production of scalar top quarks in polarized photon-photon collisions with the subsequent decay of the top squarks into b-quarks and charginos. We simulate this process by using PYTHIA6.4 for an electron beam energy 2E_beam =1000 GeV. A set of criteria for physical variables is proposed which leads to a good separation of stop signal events from top quark pair production being the main background. These criteria allow us to reconstruct the mass of the top squark provided that the neutralino mass is known.
The left-right twin Higgs(LRTH) model predicts the existence of three additional Higgs bosons: one neutral Higgs $phi^{0}$ and a pair of charged Higgs bosons $phi^{pm}$. In this paper, we studied the production of a pair of charged and neutral Higgs bosons associated with standard model gauge boson $Z$ at the ILC, i.e., $e^{+}e^{-}rightarrow Zphi^{+}phi^{-}$ and $e^{+}e^{-}rightarrow Zphi^{0}phi^{0}$. We calculate the production rate and present the distributions of the various observables, such as, the distributions of the energy and the transverse momenta of final $Z$-boson and charged Higgs boson $phi^{-}$, the differential cross section of the invariant mass of charged Higgs bosons pair, the distribution of the angle between charged Higgs bosons pair and the production angle distributions of $Z$-boson and charged Higgs boson $phi^{-}$. Our numerical results show that, for the process $e^{+}e^{-}rightarrow Zphi^{+}phi^{-}$, the production rates are at the level of $10^{-1} fb$ with reasonable parameter values. For the process of $e^{+}e^{-}rightarrow Zphi^{0}phi^{0}$, we find that the production cross section are smaller than $6times 10^{-3} fb$ in most of parameter space. However, the resonance production cross section can be significantly enhanced.
Jinshu Huang
,Gongru Lu
,Wei Xu
.
(2010)
.
"Associated production of a neutral top-Higgs with a heavy-quark pair in the gammagamma collisions at ILC"
.
Jinshu Huang
هل ترغب بارسال اشعارات عن اخر التحديثات في شمرا-اكاديميا