Charge Coupled Devices (CCDs) have been successfully used in several high energy physics experiments over the past two decades. Their high spatial resolution and thin sensitive layers make them an ...excellent tool for studying short-lived particles. The Linear Collider Flavour Identification (LCFI) collaboration is developing Column-Parallel CCDs (CPCCDs) for the vertex detector of a future Linear Collider. The CPCCDs can be read out many times faster than standard CCDs, significantly increasing their operating speed. A test stand for measuring the charge transfer inefficiency (CTI) of a prototype CPCCD has been set up. Studies of the CTI have been performed at a range of readout frequencies and operating temperatures.
The ratio of neutral Higgs field vacuum expectation values, tanβ, is one of the most important parameters to determine in either the minimal supersymmetric standard model (MSSM) or a general type-II ...two-Higgs doublet model (2HDM). Assuming an energy and integrated luminosity of s=500 GeV and L=2000 fb−1 at a future linear collider (LC), we show that a very accurate determination of tanβ will be possible for low and high tanβ values by measuring the production rates of Higgs bosons and reconstructing Higgs boson decays. In particular, based on a TESLA simulation, and assuming no other light Higgs bosons and 100⩽mA⩽200 GeV, we find that the rate for the process e+e−→bb̄A→bb̄bb̄ provides a good determination of tanβ at high tanβ. In the MSSM Higgs sector, in the sample case of mA=200 GeV, we find that the rates for e+e−→bb̄A+bb̄H→bb̄bb̄ and for e+e−→HA→bb̄bb̄ provide a good determination of tanβ at high and low tanβ, respectively. We also show that the direct measurement of the average total widths of the H and A in e+e−→HA→bb̄bb̄ events provides an excellent determination of tanβ at large values. In addition, the charged Higgs boson process e+e−→H+H−→tb̄t̄b has been studied. The sensitivity to tanβ at the LHC obtained directly from heavy Higgs boson production is briefly compared to the LC results.
We report on detailed Monte Carlo comparisons of selection variables to separate tbH
±
signal events from the standard model tt̄ background using an iterative discriminant analysis (IDA) method. ...While kinematic differences exist between the two processes whenever
, the exploration of the spin difference between the charged Higgs and the W
±
gauge boson becomes crucial in the particularly challenging case of near degeneracy of the charged Higgs boson mass with the W
±
mass. The TAUOLA package is used to decay the tau leptons emerging from the charged Higgs and W
±
boson decays taking the spin difference properly into account. We demonstrate that, even if the individual selection variables have limited discriminant power, the IDA method achieves a significant separation between the expected signal and background. For both Tevatron and LHC energies, the impact of the spin effects and H
±
mass on the separation of signal and background has been studied quantitatively. The effect of a hard transverse momentum cut to remove QCD background has been studied and it is found that the spin effects remain important. The separation is expressed in purity versus efficiency curves. The study is performed for charged Higgs boson masses between the W
±
mass and near the top mass.
A search for pair-produced doubly charged Higgs bosons has been performed using the data collected by the DELPHI detector at LEP at centre-of-mass energies between 189 and 209 GeV. No excess is ...observed in the data with respect to the Standard Model background. A lower limit for the mass of 97.3 GeV/c2 at the 95% confidence level has been set for doubly charged Higgs bosons in left–right symmetric models for any value of the Yukawa coupling between the Higgs bosons and the τ leptons.
Results of detailed simulations of the charge transfer inefficiency of a prototype serial readout CCD chip are reported. The effect of radiation damage on the chip operating in a particle detector at ...high frequency at a future accelerator is studied, specifically the creation of two electron trap levels, 0.17 eV and 0.44 eV below the bottom of the conduction band. Good agreement is found between simulations using the ISE-TCAD DESSIS program and an analytical model for the former level but not for the latter. Optimum operation is predicted to be at about 250 K where the effects of the traps is minimal; this being approximately independent of readout frequency in the range 7-50 MHz. This work has been carried out within the Linear Collider Flavour Identification (LCFI) collaboration in the context of the International Linear Collider (ILC) project.
Charge Coupled Devices (CCDs) have been successfully used in several high energy physics experiments over the past two decades. Their high spatial resolution and thin sensitive layers make them an ...excellent tool for studying short-lived particles. The Linear Collider Flavour Identification (LCFI) collaboration is developing Column-Parallel CCDs (CPCCDs) for the vertex detector of a future Linear Collider. The CPCCDs can be read out many times faster than standard CCDs, significantly increasing their operating speed. An Analytic Model has been developed for the determination of the charge transfer inefficiency (CTI) of a CPCCD. The CTI values determined with the Analytic Model agree largely with those from a full TCAD simulation. The Analytic Model allows efficient study of the variation of the CTI on parameters like readout frequency, operating temperature and occupancy.
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