Showing papers in "Physics and experiments with future linear e+ e- colliders in 2001"
TL;DR: In this paper, the authors studied the loop couplings of the Higgs boson with γγ and Zγ, and also with gluons, and showed that the deviation of the two-photon width from its SM value is generally higher than the expected inaccuracy in the measurement of Γγγ at a Photon Collider.
Abstract: After operations at the LHC and e+e− Linear Colliders it may be found that a Standard-Model-like scenario is realized. In this scenario no new particle will be discovered, except a single Higgs boson having partial widths or coupling constants with fundamental particles, whose squares are close, within anticipated experimental uncertainty, to those of the SM. Experiments at a Photon Collider can resolve whether the SM or e.g. the Two-Higgs-Doublet Model is realized in Nature. For the SM-like realizations of the 2HDM (II) we study the loop couplings of the Higgs boson with γγ and Zγ, and also with gluons. The deviation of the two-photon width from its SM value is generally higher than the expected inaccuracy in the measurement of Γγγ at a Photon Collider. The deviation is sensitive to the parameters of the Higgs self interaction.
20 citations
TL;DR: In this article, the potential of a high luminosity e+e− linear collider (LC) in the precision study of the Higgs boson profile is discussed, together with a comparison with a muon collider.
Abstract: This paper reviews the potential of a high luminosity e+e− linear collider (LC) in the precision study of the Higgs boson profile. The complementarity of the linear collider data with that from the LHC is also discussed together with a comparison with a muon collider.
17 citations
TL;DR: In this paper, a realistic study of the sensitivity to signals of strong electroweak symmetry breaking at Tesla energies using ee→WWνν and ee →ZZνν processes is presented.
Abstract: A realistic study of the sensitivity to signals of strong electroweak symmetry breaking at Tesla energies using ee→WWνν and ee→ZZνν processes is presented. Limits on α4 and α5, parameters of the electroweak chiral lagrangian, are given and discussed.
17 citations
TL;DR: SIMDET as mentioned in this paper is a parametric Monte Carlo program to simulate the response of a detector for the TESLA linear collider, with a tracking system, an electromagnetic and a hadronic calorimeter, a vertex and a luminosity detector.
Abstract: We briefly describe the principles of operation of the program package SIMDET, a parametric Monte Carlo program to simulate the response of a detector for the TESLA linear collider. Main detector components are implemented according to the TESLA Conceptual Design report, with a tracking system, an electromagnetic and a hadronic calorimeter, a vertex and a luminosity detector. Using the results from the ab initio Monte Carlo program BRAHMS, track parameters and calorimetric deposits are treated in a realistic way. Pattern recognition is emulated using cross references between generated particles and detector response. An energy flow algorithm defines the output of the program. Further improvements and completions of SIMDET are also discussed.
13 citations
TL;DR: The Next Linear Collider (NLC) is being designed by a US collaboration (FNAL, LBNL, LLNL, and SLAC) which is working closely with the Japanese collaboration that is designing the Japanese linear Collider (JLC) as discussed by the authors.
Abstract: An electron/positron linear collider with a center-of-mass energy between 0.5 and 1 TeV would be an important complement to the physics program of the LHC. The Next Linear Collider (NLC) is being designed by a US collaboration (FNAL, LBNL, LLNL, and SLAC) which is working closely with the Japanese collaboration that is designing the Japanese Linear Collider (JLC). The NLC main linacs are based on normal conducting 11 GHz rf. This paper will discuss the technical difficulties encountered as well as the many changes that have been made to the NLC design over the last year. These changes include improvements to the X-band rf system as well as modifications to the injector and the beam delivery system. They are based on new conceptual solutions as well as results from the R&D programs which have exceeded initial specifications. The net effect has been to reduce the length of the collider from about 32 km to 25 km and to reduce the number of klystrons and modulators by a factor of two. Together these lead to s...
12 citations
CERN1
TL;DR: In this article, a new generation of semi-conducting pixel sensors for detecting minimum ionising particles (m.i.p.) was designed and first prototypes were fabricated in a standard CMOS technology, guided by the very high vertex detector performances demanded in future collider experiments.
Abstract: A new generation of semi-conducting pixel sensors for detecting minimum ionising particles (m.i.p.) was designed and first prototypes were fabricated in a standard CMOS technology, guided by the very high vertex detector performances demanded in future collider experiments. The device architecture resembles CMOS cameras, a recent alternative to CCD sensors for visible light imaging. The performances of the first prototype of Monolithic Active Pixel Sensors (MAPS), called MIMOSA, were evaluated with high energy π− beams at CERN. Preliminary test results demonstrate that the sensors detect m.i.p.s with very high efficiency and signal-to-noise ratio and provide excellent spatial resolution.
10 citations
TL;DR: In this article, the top quark mass and the Higgs mass can be predicted from the infrared fixed points of the renormalization group equations, and the predicted mass is in good agreement with the experimental value.
Abstract: The electroweak symmetry may be broken by a composite Higgs which arises naturally as a bound state of the top quark if the standard model gauge fields and fermions propagate in extra dimenions. The top quark mass and the Higgs mass can be predicted from the infrared fixed points of the renormalization group equations. The top quark mass is in good agreement with the experimental value, and the Higgs boson mass is predicted to be ∼200 GeV. The bounds on the compactification scale can be quite low if all standard model fields propagate in the same extra dimensions due to the momentum conservation in extra dimensions. The current lower limits are about 300 GeV for one extra dimension and 400–800 GeV for two extra dimensions. The future collider experiments may either discover the Kaluza-Klein (KK) states of the standard model fields or raise their mass limits significantly. There may also be some other light bound states which could be observed at upcoming collider experiments.
9 citations
TL;DR: In this article, a small dependence was found when the beampipe radius is varied between 1.2 cm and 2.4 cm, and the hit precision between 3 μm and 5 μm.
Abstract: The Higgs branching ratio measurement is a premier goal of the next Linear Collider physics program. Variations of a CCD vertex detector have been studied to assess the impact of inner radius and hit precision on the measurement of the Higgs branching ratios. A small dependence is found when the beampipe radius is varied between 1.2 cm and 2.4 cm, and the hit precision between 3 μm and 5 μm.
8 citations
TL;DR: In this article, a prospective high-energy e+e− collider TESLA in the GigaZ mode on the Z resonance has been used for the measurement of the effective electroweak mixing angle to an accuracy of δ −sin2 −θeff≈±1×10−5.
Abstract: By running the prospective high-energy e+e− collider TESLA in the GigaZ mode on the Z resonance, experiments can be performed on the basis of more than 109 Z events. This will allow the measurement of the effective electroweak mixing angle to an accuracy of δ sin2 θeff≈±1×10−5. The W boson mass is likewise expected to be measurable with an error of δMW≈±6 MeV near the W+W− threshold. We review the electroweak precision tests that can be performed with these high precision measurements within the Standard Model (SM) and its minimal Supersymmetric extension (MSSM). The complementarity of direct measurements at a prospective linear e+e− collider and indirect constraints following from the measurements performed at GigaZ is emphasized.
8 citations
TL;DR: In this paper, the precision of a proposed CCD vertex detector was studied for 120 GeV/c2 and 140 GeV /c2 Higgs production at s=500 ǫGeV.
Abstract: The next Linear Collider should provide the capability to measure with precision the Higgs branching ratios, constraining the models of electroweak symmetry breaking. The precision of a proposed CCD vertex detector is studied for 120 GeV/c2 and 140 GeV/c2 Higgs production at s=500 GeV.
7 citations
TL;DR: In this paper, an improved description of final-state QCD radiation is introduced, matched to the first-order matrix elements for gluon emission in a host of decays, for processes within the Standard Model and the Minimal Supersymmetric extension thereof.
Abstract: An algorithm for an improved description of final-state QCD radiation is introduced. It is matched to the first-order matrix elements for gluon emission in a host of decays, for processes within the Standard Model and the Minimal Supersymmetric extension thereof.
TL;DR: In this article, the authors describe the O'Mega matrix element generator and the event generator WHIZARD, which cooperate in the automated production of efficient unweighted event generators for linear collider physics.
Abstract: I describe the optimizing matrix element generator O’Mega [1,2] and Wolfgang Kilian’s event generator generator WHIZARD [3]. These tools cooperate in the automated production of efficient unweighted event generators for linear collider physics.
TL;DR: In this article, the authors proposed a method to extract the Higgs boson couplings to fermions and bosons from the various measurements which are possible at a future linear e+e− collider using a global fit, which provides optimal sensitivity to the couplings and accounts for experimental correlations among the measurements.
Abstract: We study the prospects to extract the Higgs boson couplings to fermions and bosons from the various measurements which are possible at a future linear e+e− collider using a global fit. The method provides optimal sensitivity to the couplings and accounts for experimental correlations among the measurements. For a Higgs boson mass of 120 GeV and an integrated luminosity of 500fb−1 at 350 GeV or 500 GeV and 1ab−1 at 800 GeV, the coupling to massive gauge bosons can be determined with approximately 1% accuracy while the couplings to heavy fermions (tau leptons, charm, bottom, and top quarks) can be determined with 2–3% experimental accuracy. Except for the precise top quark coupling the whole parameter set can already be obtained at 500 GeV center-of-mass energy.
TL;DR: In this paper, the authors present an overview of the current status of the background calculations including the corresponding detector simulations, and give a detailed analysis of the expected background sources in the interaction point.
Abstract: The aim of the Compact Linear Collider (CLIC) study [1] is to design a high-energy linear e+e− collider. The effort is focused on an accelerator with a center-of-mass energy of Ecm=3 TeV and a luminosity of L=1035 cm−2 s−1. Careful study of the expected background in the interaction point (IP) of this machine is necessary. In CLIC, the background sources are expected to be more severe than in other studies like JLC, NLC and TESLA because of the higher luminosity, higher energy and stronger beam-beam effects. Coherent pair creation, which is almost completely absent at lower energies, will be very important. This paper gives an overview of the current status of the background calculations including the corresponding detector simulations.
TL;DR: In this paper, the production and decay of heavy charged Higgs bosons at a 800 GeV e+e− linear collider were studied and the analysis of the H+H−→tbtb, expected to be dominant in the MSSM, and H +H−−→W+h0W−h0 decay modes leading to the same final state consisting of two W bosons and four b quarks, provided with a determination of the boson mass to 1'oGeV/c2 and of the production cross section with 10%
Abstract: The production and decay of heavy charged Higgs bosons at a 800 GeV e+e− linear collider have been studied. The analysis of the H+H−→tbtb, expected to be dominant in the MSSM, and H+H−→W+h0W−h0 decay modes leading to the same final state consisting of two W bosons and four b quarks, provides with a determination of the boson mass to 1 GeV/c2 and of the production cross section with 10% accuracy for 500 fb−1 of data.
TL;DR: Suitable beam polarimeter concepts for the TESLA linear collider have been investigated in this paper, and a specific Compton polarimeter design is proposed for this purpose, which is based on a beam-polarimeter design.
Abstract: Suitable beam polarimeter concepts for the TESLA linear collider have been investigated A specific Compton polarimeter design is proposed
TL;DR: Using a global fit to Z-pole observables, the 3sigma bound on the scale of quantum gravity is found to be 28 TeV for n = 2.
Abstract: We consider a model with extra compact dimensions in which only gravity exists in the 4+n dimensional bulk. If the gravitational connection is not assumed to be symmetric, that is, unless torsion is artificially set to zero, then a universal contact interaction among the fermions on the 4-dimensional wall is induced. Using a global fit to Z-pole observables, we find the 3σ bound on the scale of quantum gravity to be MS=28 TeV for n=2. If Dirac or light sterile neutrinos are present, the data from SN1987A increase the bound to nMS⩾210 TeV.
TL;DR: This work first evaluates the basic tracking performance, then the flavor tagging performance, and the energy dependence of the performance of the CCD (Charged Coupled Device) pixel vertex detector using a neural network approach.
Abstract: The ability to distinguish the flavor of jets formed in an event is a very important parameter to evaluate, when designing a high performance vertex detector to use in a future e+e− linear collider. In this work we concentrate on a CCD (Charged Coupled Device) pixel vertex detector. We first evaluate the basic tracking performance. We then estimate the flavor tagging performance of the present detector layout, using a neural network approach. We conclude by studying the energy dependence of the performance.
TL;DR: In this article, the theoretical analysis including the most relevant channels for the production of neutral Higgs boson pairs at high-energy and high-luminosity e+e− linear colliders is presented.
Abstract: In order to verify the Higgs mechanism experimentally, the Higgs self-couplings have to be probed. These couplings allow the reconstruction of the characteristic Higgs potential responsible for the electroweak symmetry breaking. The couplings are accessible in a variety of multiple Higgs production processes. The theoretical analysis including the most relevant channels for the production of neutral Higgs boson pairs at high-energy and high-luminosity e+e− linear colliders will be presented in this note.
TL;DR: In this paper, a method based on sampling of the jet charged multiplicity sensitive to the long decay length and large decay multiplicity of heavy flavor hadrons is proposed and the expected performances for the tagging of e+e−→bb events at s=3
Abstract: Jet flavor identification in multi-TeV e+e− collisions is expected to provide insights on new phenomena at scales beyond those probed by the LHC. The anticipated high track density and jet collimation represent a new challenge to jet tagging algorithms. A method, based on the sampling of the jet charged multiplicity, sensitive to the long decay length and large decay multiplicity of heavy flavor hadrons is proposed and the expected performances for the tagging of e+e−→bb events at s=3 TeV are discussed.
TL;DR: In this paper, the authors discuss the ultimate precision for ALR, and therefore for the weak mixing angle, at a high luminosity Linear Collider, and conclude that a compromise between peak luminosity and precision will be a likely outcome.
Abstract: We discuss the ultimate precision for ALR, and therefore for the weak mixing angle, at a high luminosity Linear Collider. Drawing on our experience at the SLC, and considering various machine parameter sets for the NLC and for TESLA, it emerges that a compromise between peak luminosity and precision will be a likely outcome. This arises due to the severe requirements on the uncertainty in the luminosity weighted collision energy (ECM). We consider the cases with and without a polarized positron beam.
TL;DR: In this paper, the authors describe measurements of the space point resolution of a GEM with relatively large hexagonal pads for 4.5 keV x-rays with two independent methods, using charge sharing and using induction signals.
Abstract: The Gas Electron Multiplier (GEM) is a leading candidate for the readout of the Time Projection Chamber (TPC) at a future linear collider detector. This presentation describes measurements of the space point resolution of a GEM with relatively large hexagonal pads. Resolution of approximately 50 μm is achieved for 4.5 keV x-rays with two independent methods, using charge sharing and using induction signals.
TL;DR: The first choice of the ECFA/DESY study group for a TESLA detector was an iron/scintillator-tile sandwich calorimeter as discussed by the authors, which operates in a 4 T longitudinal magnetic field.
Abstract: This is a report on design and performance studies towards an iron/scintillator-tile sandwich calorimeter which is the first choice of the ECFA/DESY study group for a TESLA detector. The hadronic calorimeter (HCAL) is combined with an electromagnetic calorimeter (ECAL) in front, both operate in a 4 T longitudinal magnetic field. The ECAL is also presented in these proceedings [1].
TL;DR: In this article, a bottom-up extrapolation from the electroweak scale to the GUT scale is explained and both a universal minimal supergravity and a gaugino-mediated model are presented as examples.
Abstract: High precision measurements at the linear collider will allow a model-independent reconstruction of nature at high energy scales. The method of bottom-up extrapolation from the electroweak scale to the GUT scale is explained and both a universal minimal supergravity and a gaugino-mediated model are presented as examples. Comparisons are made with the LHC-only case.
TL;DR: In this paper, the dE/dx resolution of the TESLA-TPC has been studied using a toy Monte Carlo simulation based on measured cluster size distributions, and an optimum number of 240 samples has been found (5 mm sampling length) with a simulated 4.1% particle separation power.
Abstract: The dE/dx resolution of the TESLA-TPC has been studied using a toy Monte Carlo simulation based on measured cluster size distributions. Various parameters like sampling length, electronics noise, crosstalk etc. have been investigated. An optimum number of 240 samples has been found (5 mm sampling length) with a simulated dE/dx resolution of 4.1%. The particle separation power has been estimated.
TL;DR: In this article, the current design of the interaction region of the TESLA superconducting linear collider is reviewed, in particular the recent upgrades of the collimation section and the beam extraction lines.
Abstract: We review the current design of the interaction region of the TESLA superconducting linear collider. We describe in particular the recent upgrades of the collimation section and the beam extraction lines.
TL;DR: In this article, the authors compare heavy quark tagging and anti-tagging efficiencies for vertex detectors with different inner raddi using the topological vertex technique developed at the SLC/SLD experiment.
Abstract: We compare heavy quark tagging and anti-tagging efficiencies for vertex detectors with different inner raddi using the topological vertex technique developed at the SLC/SLD experiment. Charm tagging benefits by going to very small inner radii.
TL;DR: The North American Linear Collider Detector group has developed a simulation program package based on the ROOT system as mentioned in this paper, which consists of Fast simulation, the reconstruction of the Full simulated data, and physics analysis utilities.
Abstract: The North American Linear Collider Detector group has developed a simulation program package based on the ROOT system. The package consists of Fast simulation, the reconstruction of the Full simulated data, and physics analysis utilities.
TL;DR: In this paper, the current status of the TESLA superconducting e+e− linear collider project is reviewed and a review of the design studies on the TEL project is presented.
Abstract: We review the current status of the R&D results and design studies on the TESLA superconducting e+e− linear collider project.