共查询到20条相似文献,搜索用时 0 毫秒
1.
J Kalinowski 《Pramana》2000,55(1-2):259-264
After the supersymmetric particles have been discovered, the priority will be to determine independently the fundamental parameters
to reveal the structure of the underlying supersymmetric theory. In my talk I discuss how the chargino sector can be reconstructed
completely by measuring the cross-sections with polarized beams at e
+
e
− collider experiments: e
+
e
− →
[i, j=1, 2]. The closure of the two-chargino system can be investigated by analysing sum rules for the production cross-sections. 相似文献
2.
At the CEPC (Circular Electron Positron Collider), which is proposed by the Chinese high energy physics community, the dominant background comes from radiative Bhabha scattering and the beamstrahlung effect according to preliminary research. Therefore, it is necessary to incorporate a collimator system to intercept particles that may be lost near the interaction region (IR). In this paper, we introduce some limitations in choosing the position and width of the collimators. A certain parameter range is determined which is confined by the β function and the width of the collimators. A suitable choice of the half width is made by exploring this parameter range. A simulation of the particle loss rate in the IR and the hit density in the vertex detector with and without the collimators shows that the set of parameters of the collimators we designed is appropriate and effective. 相似文献
3.
Yuhang Tan Xin Shi Ryuta Kiuchi Manqi Ruan Maoqiang Jing Dan Yu Kaili Zhang Xinchou Lou Xin Mo Gang Li Susmita Jyotishmati 《中国物理C(英文版)》2020,44(12):123001-123001-8
The Circular Electron Positron Collider (CEPC), proposed as a future Higgs boson factory, will operate at a center-of-mass energy of 240 GeV and will accumulate 5.6 ab?1 of integrated luminosity in 7 years. In this study, we estimate the upper limit of BR(begin{document}$H rightarrow$end{document} ![]()
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inv) for three independent channels, including two leptonic channels and one hadronic channel, at the CEPC. Based on the full simulation analysis, the upper limit of BR(begin{document}$H rightarrow$end{document} ![]()
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inv) could reach 0.26% at the 95% confidence level. In the Stand Model (SM), the Higgs boson can only decay invisibly via begin{document}$Hrightarrow ZZ^astrightarrownuoverline{nu}nuoverline{nu}$end{document} ![]()
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, so any evidence of invisible Higgs decays that exceed BR(begin{document}$H rightarrow$end{document} ![]()
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inv) of the SM will indicate a phenomenon that is beyond the SM (BSM). The invariant mass resolution of the visible hadronic decay system begin{document}$ZH(Z rightarrow qq$end{document} ![]()
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, begin{document}$ H rightarrow$end{document} ![]()
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inv) is simulated, and the physics requirement at the CEPC detector for reaching this is given. 相似文献
4.
Expected measurement precision of the branching ratio of the Higgs boson decaying to the di-photon at the CEPC 下载免费PDF全文
This paper presents the prospects of measuring \begin{document}$\sigma(e^{+} e^{-} \to ZH)\times {\rm Br}(H \to \gamma \gamma)$\end{document} ![]()
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in three Z decay channels \begin{document}$ Z \to q \bar{q}/ {\mu ^ + }{\mu ^ - }/ \nu \bar \nu $\end{document} ![]()
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using the baseline detector with \begin{document}$\sqrt{s} = 240$\end{document} ![]()
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GeV at the Circular Electron Positron Collider (CEPC). Simulated Monte Carlo events were generated and scaled to an integrated luminosity of 5.6 ab–1 to mimic the data. Extrapolated results to 20 ab–1 are also reported. The expected statistical precision of these measurements after combining three channels of Z boson decay was 7.7%. With some preliminary estimation on the systematical uncertainties, the total precision is 7.9%. The performance of the CEPC electro-magnetic calorimeter (ECAL) was studied by smearing the photon energy resolution in simulated events in the \begin{document}$e^{+} e^{-} \to ZH \to q\bar q\gamma \gamma $\end{document} ![]()
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channel. In the present ECAL design, the stochastic term in resolution plays the dominant role in the precision of Higgs measurements in the \begin{document}$H \to \gamma \gamma $\end{document} ![]()
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channel. The impact of the resolution on the measured precision of \begin{document}$\sigma(ZH)\times {\rm Br}(ZH \to q\bar q\gamma \gamma)$\end{document} ![]()
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as well as the optimization of the ECAL constant and stochastic terms were studied for further detector design. 相似文献
5.
The Circular Electron-Positron Collider(CEPC) is a future Higgs factory proposed by the Chinese high energy physics community. It is planned to operate at a center-of-mass energy of 240–250 Ge V and is expected to accumulate an integrated luminosity of 5 ab~(-1) over ten years of operation. At the CEPC, Higgs bosons will be dominantly produced from the ZH associated process. The vast number of Higgs events collected will enable precise studies of its properties, including Yukawa couplings to massive particles. With GEANT4-based simulation of detector effects, we study the feasibility of measuring the Higgs boson decaying into a pair of muons at the CEPC.The results with and without information from the Z boson decay products are provided, showing that a signal significance of over 10 standard deviations can be achieved and the H-μ-μ coupling can be measured within 10%accuracy. 相似文献
6.
H. Fraas F. Franke G. Moortgat-Pick F. von der Pahlen A. Wagner 《The European Physical Journal C - Particles and Fields》2003,29(4):587-595
We study chargino pair production on the heavy Higgs resonances at a muon collider in the MSSM. At
GeV cross sections up to 2 pb are reached depending on the supersymmetric scenario and the beam energy spread. The resonances of the scalar and pseudoscalar Higgs bosons may be separated for
. Our aim is to determine the ratio of the chargino couplings to the heavy scalar and pseudoscalar Higgs boson independently of the specific chargino decay characteristics. The precision of the measurement depends on the energy resolution of the muon collider and on the error in the measurement of the cross sections of the non-Higgs channels including an irreducible standard model background. With a high energy resolution the systematic error can be reduced to the order of a few percent.Received: 6 March 2003, Revised: 21 May 2003, Published online: 3 July 2003 相似文献
7.
W. Kilian J. Reuter T. Robens 《The European Physical Journal C - Particles and Fields》2006,48(2):389-400
We present a Monte Carlo event generator for simulating chargino pair production at the International Linear Collider (ILC) at next-to-leading order in the electroweak couplings. By properly resumming photons in the soft and collinear regions, we avoid negative event weights, so the program can simulate physical (unweighted) event samples. Photons are explicitly generated throughout the range where they can be experimentally resolved. Inspecting the dependence on the cutoffs separating the soft and collinear regions, we evaluate the systematic errors due to soft and collinear approximations. In the resummation approach, the residual uncertainty can be brought down to the per-mil level, coinciding with the expected statistical uncertainty at the ILC. PACS 12.15.Lk; 13.40.Ks; 13.66.Hk; 14.80.Ly 相似文献
8.
Ou-Zheng Xiao 《中国物理 B》2022,31(8):88401-088401
To reduce the energy demand and operation cost for circular electron positron collider (CEPC), the high efficiency klystrons are being developed at Institute of High Energy Physics, Chinese Academy of Sciences. A 800-kW continuous wave (CW) klystron operating at frequency of 650-MHz has been designed. The results of beam-wave interaction simulation with several different codes are presented. The efficiency is optimized to be 65% with a second harmonic cavity in three-dimensional (3D) particle-in-cell code CST. The effect of cavity frequency error and mismatch load on efficiency of klystron have been investigated. The design and cold test of reentrant cavities are described, which meet the requirements of RF section design. So far, the manufacturing and high-power test of the first klystron prototype have been completed. When the gun operated at DC voltage of 80 kV and current of 15.4 A, the klystron peak power reached 804 kW with output efficiency of about 65.3% at 40% duty cycle. The 1-dB bandwidth is ±0.8 MHZ. Due to the crack of ceramic window, the CW power achieved about 700 kW. The high-power test results are in good agreement with 3D simulation. 相似文献
9.
In the minimal supersymmetric standard model (MSSM), we study the light Higgs boson radiation off a light-chargino pair in the process
at linear colliders with
GeV. We analyze cross sections in the regions of the MSSM parameter space where the process
cannot proceed via on-shell production and subsequent decay of either heavier charginos or the pseudoscalar Higgs boson A. Cross sections up to a few fb are allowed, according to present experimental limits on the Higgs boson, chargino and sneutrino masses. We also show how a measurement of the
production rate could provide a determination of the Higgs boson couplings to charginos.Received: 24 June 2004, Revised: 13 May 2005, Published online: 19 July 2005 相似文献
10.
A Monte-Carlo analysis on production and decay of supersymmetric charginos at a future photon-collider is presented. A photon collider offers the possibility of a direct branching-ratio measurement. In this study, the process
has been considered for a specific mSUGRA scenario. Various backgrounds and a parameterised detector simulation have been included. Depending on the centre-of-mass energy, a statistical error for the directly measurable branching ratio BR(
) of up to 3.5% can be reached.Received: 14 March 2005, Revised: 31 May 2005, Published online: 28 June 2005G. Klämke: Now at: Institut für Theoretische Physik, Universität Karlsruhe, Wolfgang-Gaede-Str. 1, 76131 Karlsruhe, Germany 相似文献
11.
安芬芬 白羽 陈春晖 陈新 陈振兴 Joao Guimaraes da Costa 崔振崴 方亚泉 付成栋 高俊 高艳彦 高原宁 葛韶锋 顾嘉荫 郭方毅 郭军 韩涛 韩爽 何红建 何显柯 何小刚 胡继峰 徐士杰 金山 荆茂强 Susmita Jyotishmati Ryuta Kiuchi 郭家铭 赖培筑 李博扬 李聪乔 李刚 李海峰 李亮 李数 李通 李强 梁浩 梁志均 廖立波 刘波 刘建北 刘涛 刘真 娄辛丑 马连良 Bruce Mellado 莫欣 Mila Pandurovic 钱剑明 钱卓妮 Nikolaos Rompotis 阮曼奇 Alex Schuy 单连友 史静远 史欣 苏淑芳 王大勇 王锦 王连涛 王贻芳 魏彧骞 许悦 杨海军 杨迎 姚为民 于丹 张凯栗 张照茹 赵明锐 赵祥虎 周宁 《中国物理C(英文版)》2019,(4)
The discovery of the Higgs boson with its mass around 125 GeV by the ATLAS and CMS Collaborations marked the beginning of a new era in high energy physics.The Higgs boson will be the subject of extensive studies of the ongoing LHC program.At the same time,lepton collider based Higgs factories have been proposed as a possible next step beyond the LHC,with its main goal to precisely measure the properties of the Higgs boson and probe potential new physics associated with the Higgs boson.The Circular Electron Positron Collider(CEPC)is one of such proposed Higgs factories.The CEPC is an e~+e~- circular collider proposed by and to be hosted in China.Located in a tunnel of approximately 100 km in circumference,it will operate at a center-of-mass energy of 240 GeV as the Higgs factory.In this paper,we present the first estimates on the precision of the Higgs boson property measurements achievable at the CEPC and discuss implications of these measurements. 相似文献
12.
13.
G. Abbiendi et al. 《The European Physical Journal C - Particles and Fields》2000,14(2):187-198
A search for charginos and neutralinos, predicted by supersymmetric theories, is performed using a data sample of 182.1 pb taken at a centre-of-mass energy of 189 GeV with the OPAL detector at LEP. No evidence for chargino or neutralino production
is found. Upper limits on chargino and neutralino pair production (, ) cross-sections are obtained as a function of the chargino mass (), the lightest neutralino mass () and the second lightest neutralino mass (). Within the Constrained Minimal Supersymmetric Standard Model framework, and for GeV, the 95% confidence level lower limits on are 93.6 GeV for and 94.1 GeV for . These limits are obtained assuming a universal scalar mass 500 GeV. The corresponding limits for all are 78.0 and 71.7 GeV. The 95% confidence level lower limits on the lightest neutralino mass, valid for any value of are 32.8 GeV for GeV and 31.6 GeV for all .
Received: 14 October 1999 / Published online: 6 March 2000 相似文献
14.
Dark sector may couple to the Standard Model via one or more mediator particles.We discuss two types of mediators:the dark photon A’and the dark scalar mediatorΦ.The total cross-sections and various differential distributions of the processes e+e-→qqA’and e+e→qqφ(q=u,d,c,s and b quarks)are discussed.We focus on the study of the invisible due to the cleaner background at future e+e-colliders.It is found that the kinematic distributions of the two-jet system could be used to identify(or exclude)the dark photon and the dark scalar mediator,as well as to distinguish between them.We further study the possibility of a search for dark photons at a future CEPC experiment with s1/2=91.2 GeV and 240 GeV.With CEPC running at s1/2=91.2 GeV,it would be possible to perform a decisive measurement of the dark photon(20 GeV相似文献
15.
An optimal scheme for top quark mass measurement near the tt threshold at future e+e- colliders 下载免费PDF全文
A top quark mass measurement scheme near the tt production threshold in future e+e- colliders, e.g.the Circular Electron Positron Collider (CEPC), is simulated. A χ2 fitting method is adopted to determine the number of energy points to be taken and their locations. Our results show that the optimal energy point is located near the largest slope of the cross section v. beam energy plot, and the most efficient scheme is to concentrate all luminosity on this single energy point in the case of one-parameter top mass fitting. This suggests that the so-called data-driven method could be the best choice for future real experimental measurements. Conveniently, the top mass statistical uncertainty can also be calculated directly by the error matrix even without any sampling and fitting. The agreement of the above two optimization methods has been checked. Our conclusion is that by taking 50 fb-1 total effective integrated luminosity data, the statistical uncertainty of the top potential subtracted mass can be suppressed to about 7 MeV and the total uncertainty is about 30 MeV. This precision will help to identify the stability of the electroweak vacuum at the Planck scale. 相似文献
16.
Gounaris G. J. Layssac J. Renard F. M. 《Zeitschrift fur Physik C Particles and Fields》1994,61(1):139-145
A fit is made to the data for the proton structure function up toQ 2=10 GeV2, including the real γp total cross-section. It is economical and simple, and its form is motivated by physical principles. It is extrapolated down to very small values ofx. Data for the ratio νW 2 n /νW 2 p are also fitted. 相似文献
17.
《中国物理C(英文版)》2019,(11)
We propose to study the flavor properties of the top quark at the future Circular Electron Positron Collider(CEPC) in China.We systematically consider the full set of 56 real parameters that characterize the flavor-changing neutral interactions of the top quark,which can be tested at CEPC in the single top production channel.Compared with the current bounds from the LEP2 data and the projected limits at the high-luminosity LHC,we find that CEPC could improve the limits of the four-fermion flavor-changing coefficients by one to two orders of magnitude,and would also provide similar sensitivity for the two-fermion flavor-changing coefficients.Overall,CEPC could explore a large fraction of currently allowed parameter space that will not be covered by the LHC upgrade.We show that the c-jet tagging capacity at CEPC could further improve its sensitivity to top-charm flavor-changing couplings.If a signal is observed,the kinematic distribution as well as the c-jet tagging could be exploited to pinpoint the various flavor-changing couplings,providing valuable information about the flavor properties of the top quark. 相似文献
18.
A search for charginos and neutralinos, predicted by supersymmetric theories, has been performed using a data sample of pb at centre-of-mass energies of 170 and 172 GeV with the OPAL detector at LEP. No evidence for these particles has been found. The results are combined with
those from previous OPAL chargino and neutralino searches at lower energies to obtain limits. Exclusion regions at 95% C.L.
of parameters of the Minimal Supersymmetric Standard Model are determined. Within this framework, for , lower mass limits are placed on the lightest chargino and the three lightest neutralinos. The 95% C.L. lower mass limit
on the lightest chargino, assuming that it is heavier than the lightest neutralino by more than 10 GeV, is 84.5 GeV for the
case of a large universal scalar mass ( 1 TeV) and 65.7 GeV for the smallest compatible with current limits on the sneutrino mass and slepton cross-sections. The lower limit on the lightest neutralino
mass at 95% C.L. for is 24.7 GeV for TeV and 13.3 GeV for the minimum scenario. These mass limits are higher for increasing values of . The interpretation of the limits in terms of gluino and scalar quark mass limits is also given.
Received: 11 July 1997 / Online publication: February 26, 1998 相似文献
19.
We calculate direct gaugino pair production at hadron colliders at next-to-leading order of perturbative QCD, resumming simultaneously large logarithms in the small transverse-momentum and threshold regions to next-to-leading logarithmic accuracy. Numerical predictions are presented for transverse momentum and invariant mass spectra as well as for total cross sections and compared to results obtained at fixed order and with pure transverse-momentum and threshold resummation. We find that our new results are in general in good agreement with the previous ones, but often even more precise. 相似文献
20.
We present a complete analysis of threshold resummation effects on direct light and heavy gaugino pair production at the Tevatron and the LHC. Based on a new perturbative calculation at next-to-leading order of SUSY-QCD, which includes also squark mixing effects, we resum soft gluon radiation in the threshold region at leading and next-to-leading logarithmic accuracy, retaining at the same time the full SUSY-QCD corrections in the finite coefficient function. This allows us to correctly match the resummed to the perturbative cross section. Universal subleading logarithms are resummed in full matrix form. We find that threshold resummation slightly increases and considerably stabilizes the invariant mass spectra and total cross sections with respect to the next-to-leading order calculation. For future reference, we present total cross sections and their theoretical errors in tabular form for several commonly used SUSY benchmark points, gaugino pairs, and hadron collider energies. 相似文献