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K. Mönig

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DOI: 10.1016/j.physletb.2004.06.001
2004
Cited 5,397 times
Review of Particle Physics
We derive non-flat cosmological models for two cases (i.e., dust and radiation) in the context of Møller’s tetradic theory (MTT) of gravitation using the tetrad that creates the non-flat Friedmann–Robertson–Walker (FRW) metric. These two models are affected by the free dimensional parameter, λ, that characterized MTT, which approaches zero in the flat case for both models. Using standard definitions of thermodynamics, we calculate the radius horizon, Hawking temperature, and entropy of our non-flat models in the framework of cosmology and show the effect of λ on open and closed universes. We then use the first law of thermodynamics to construct non-flat cosmological models via the non-extensive thermodynamic approach. The resulting models are affected by λ and the extensive parameter, δ, which quantifies the effect of non-extensive thermodynamics. When we set, λ=0 and δ=1, we return to Einstein’s general relativity models. We study the evolution of our models in the presence of collisionless non-relativistic matter and describe precise forms of the dark energy density and equation-of-state parameter constraining the non-extensive thermodynamic parameter. We show that insertion of the non-extensive thermodynamic parameter affects the non-flat FRW universe in a manner that noticeably differs from that observed under normal thermodynamics. We also show that the deceleration of the open universe behaves as dark energy in a future epoch, i.e., when the redshift approaches −1, i.e., z≈−1.
DOI: 10.1016/j.physletb.2008.07.018
2008
Cited 4,337 times
Review of Particle Physics
This biennial Review summarizes much of particle physics. Using data from previous editions, plus 2778 new measurements from 645 papers, we list, evaluate, and average measured properties of gauge bosons, leptons, quarks, mesons, and baryons. We also summarize searches for hypothetical particles such as Higgs bosons, heavy neutrinos, and supersymmetric particles. All the particle properties and search limits are listed in Summary Tables. We also give numerous tables, figures, formulae, and reviews of topics such as the Standard Model, particle detectors, probability, and statistics. Among the 108 reviews are many that are new or heavily revised including those on CKM quark-mixing matrix, Vud & Vus, Vcb & Vub, top quark, muon anomalous magnetic moment, extra dimensions, particle detectors, cosmic background radiation, dark matter, cosmological parameters, and big bang cosmology. A booklet is available containing the Summary Tables and abbreviated versions of some of the other sections of this full Review. All tables, listings, and reviews (and errata) are also available on the Particle Data Group website: http://pdg.lbl.gov.
DOI: 10.1103/physrevd.66.010001
2002
Cited 2,822 times
Review of Particle Properties
This biennial Review summarizes much of Particle Physics. Using data from previous editions, plus 2205 new measurements from 667 papers, we list, evaluate, and average measured properties of gauge bosons, leptons, quarks, mesons, and baryons. We also summarize searches for hypothetical particles such as Higgs bosons, heavy neutrinos, and supersymmetric particles. All the particle properties and search limits are listed in Summary Tables. We also give numerous tables, figures, formulae, and reviews of topics such as the Standard Model, particle detectors, probability, and statistics. This edition features expanded coverage of CP violation in B mesons and of neutrino oscillations. For the first time we cover searches for evidence of extra dimensions (both in the particle listings and in a new review). Another new review is on Grand Unified Theories. A booklet is available containing the Summary Tables and abbreviated versions of some of the other sections of this full Review. All tables, listings, and reviews (and errata) are also available on the Particle Data Group website: http://pdg.lbl.gov.
DOI: 10.1103/physrevd.54.1
1996
Cited 1,683 times
Review of Particle Physics
This biennial review summarizes much of Particle Physics. Using data from previous editions, plus 1900 new measurements from 700 papers, we list, evaluate, and average measured properties of gauge bosons, leptons, quarks, mesons, and baryons. We also summarize searches for hypothetical particles such as Higgs bosons, heavy neutrinos, and supersymmetric particles. All the particle properties and search limits are listed in Summary Tables. We also give numerous tables, figures, formulae, and reviews of topics such as the Standard Model, particle detectors, probability, and statistics. A booklet is available containing the Summary Tables and abbreviated versions of some of the other sections of this full Review.
DOI: 10.1016/0370-2693(88)91523-7
1988
Cited 1,456 times
A measurement of the spin asymmetry and determination of the structure function g1 in deep inelastic muon-proton scattering
The spin asymmetry in deep inelastic scattering of longitudinally polarised muons by longitudinally polarised protons has been measured over a large x range (0.01<x<0.7). The spin-dependent structure function g1(x) for the proton has been determined and its integral over x found to be 0.114±0.012±0.026, in disagreement with the Ellis-Jaffe sum rule. Assuming the validity of the Bjorken sum rule, this result implies a significant negative value for the integral of g1 for the neutron. These values for the integrals of g1 lead to the conclusion that the total quark spin constitutes a rather small fraction of the spin of the nucleon.
DOI: 10.1016/0550-3213(89)90089-8
1989
Cited 1,004 times
An investigation of the spin structure of the proton in deep inelastic scattering of polarised muons on polarised protons
The spin asymmetry in deep inelastic scattering of longitudinally polarised muons by longitudinally polarised protons has been measured in the range 0.01<×<0.7. The spin dependent structure function g1(x) for the proton has been determined and, combining the data with earlier SLAC measurements, its integral over x found to be 0.126±0.010(stat.)±0.015(syst.), in disagreement with the Ellis-Jaffe sum rule. Assuming the validity of the Biorken sum rule, this result implies a significant negative value for the integral of g1 for the neutron. These integrals lead to the conclusion, in the naïve quark parton model, that the total quark spin constitutes a rather small fraction of the spin of the nucleon. Results are also presented on the asymmetries in inclusive hadron production which are consistent with the above picture.
DOI: 10.1140/epjc/s10052-014-3046-5
2014
Cited 472 times
The global electroweak fit at NNLO and prospects for the LHC and ILC
For a long time, global fits of the electroweak sector of the Standard Model (SM) have been used to exploit measurements of electroweak precision observables at lepton colliders (LEP, SLC), together with measurements at hadron colliders (Tevatron, LHC), and accurate theoretical predictions at multi-loop level, to constrain free parameters of the SM, such as the Higgs and top masses. Today, all fundamental SM parameters entering these fits are experimentally determined, including information on the Higgs couplings, and the global fits are used as powerful tools to assess the validity of the theory and to constrain scenarios for new physics. Future measurements at the Large Hadron Collider (LHC) and the International Linear Collider (ILC) promise to improve the experimental precision of key observables used in the fits. This paper presents updated electroweak fit results using newest NNLO theoretical predictions, and prospects for the LHC and ILC. The impact of experimental and theoretical uncertainties is analysed in detail. We compare constraints from the electroweak fit on the Higgs couplings with direct LHC measurements, and examine present and future prospects of these constraints using a model with modified couplings of the Higgs boson to fermions and bosons.
DOI: 10.1140/epjc/s10052-012-2205-9
2012
Cited 318 times
The electroweak fit of the standard model after the discovery of a new boson at the LHC
In view of the discovery of a new boson by the ATLAS and CMS Collaborations at the LHC, we present an update of the global Standard Model (SM) fit to electroweak precision data. Assuming the new particle to be the SM Higgs boson, all fundamental parameters of the SM are known allowing, for the first time, to overconstrain the SM at the electroweak scale and assert its validity. Including the effects of radiative corrections and the experimental and theoretical uncertainties, the global fit exhibits a p-value of 0.07. The mass measurements by ATLAS and CMS agree within 1.3σ with the indirect determination $M_{H}=94^{\,+25}_{\,-22}~\mathrm{GeV}$ . Within the SM the W boson mass and the effective weak mixing angle can be accurately predicted to be M W =80.359±0.011 GeV and $\sin ^{2}\theta ^{\ell }_{{\rm eff}}= 0.23150\pm 0.00010$ from the global fit. These results are compatible with, and exceed in precision, the direct measurements. For the indirect determination of the top quark mass we find $m_{t}= 175.8^{\:+2.7}_{\:-2.4}~ \mathrm {GeV}$ , in agreement with the kinematic and cross-section-based measurements.
DOI: 10.1140/epjc/s10052-018-6131-3
2018
Cited 280 times
Update of the global electroweak fit and constraints on two-Higgs-doublet models
We present an update of the global fit of the Standard Model electroweak sector to latest experimental results. We include new kinematic top quark and W boson mass measurements from the LHC, a $$\sin \!^2\theta ^{\ell }_{\mathrm{eff}}$$ result from the Tevatron, and a new evaluation of the hadronic contribution to $$\alpha (M_Z^2)$$ . We present tests of the internal consistency of the electroweak Standard Model and updated numerical predictions of key observables. The electroweak data combined with measurements of the Higgs boson coupling strengths and flavour physics observables are used to constrain parameters of two-Higgs-doublet models.
DOI: 10.1016/j.physrep.2007.12.003
2008
Cited 222 times
Polarized positrons and electrons at the linear collider
The proposed International Linear Collider (ILC) is well-suited for discovering physics beyond the Standard Model and for precisely unraveling the structure of the underlying physics. The physics return can be maximized by the use of polarized beams. This report shows the paramount role of polarized beams and summarizes the benefits obtained from polarizing the positron beam, as well as the electron beam. The physics case for this option is illustrated explicitly by analyzing reference reactions in different physics scenarios. The results show that positron polarization, combined with the clean experimental environment provided by the linear collider, allows to improve strongly the potential of searches for new particles and the identification of their dynamics, which opens the road to resolve shortcomings of the Standard Model. The report also presents an overview of possible designs for polarizing both beams at the ILC, as well as for measuring their polarization.
DOI: 10.1016/0370-2693(88)91872-2
1988
Cited 216 times
Measurement of the ratios of deep inelastic muon-nucleus cross sections on various nuclei compared to deuterium
Results are presented on the ratios of the deep inelastic muon-nucleus cross sections for carbon, copper and tin nuclei to those measured on deuterium. The data confirm that the structure functions of the nucleon measured in nuclei are different from those measured on quasi-free nucleons in deuterium. The kinematic range of the data is such that 〈Q2〉 ∼ 5 GeV2 at x ∼ 0.03, increasing to 〈Q2〉 ∼ 35 GeV2 for x ∼ 0.65. The measured cross section ratios are less than unity for x ≲ 0.05 and for 0.25 ≲ x < 0.7. The decrease of the ratio below unity for low x becomes larger as A increases as might be expected from nuclear shadowing. However, this occurs at relatively large values of Q2 (∼ 5 GeV2) indicating that such shadowing is of patrionic origin.
DOI: 10.1140/epjc/s2003-01355-5
2003
Cited 197 times
Searches for supersymmetric particles in e + e- collisions up to 208 GeV and interpretation of the results within the MSSM
DELPHI data collected at centre-of-mass energies up to 208 GeV have been analysed to search for charginos, neutralinos and sfermions in the framework of the Minimal Supersymmetric Standard Model (MSSM) with R-parity conservation. No evidence for a signal was found in any of the channels. The results of each search were used to derive limits on production cross-sections and particle masses. In addition, the combined result of all searches excludes regions in the parameter space of the constrained MSSM, leading to limits on the mass of the Lightest Supersymmetric Particle and other supersymmetric particles.
DOI: 10.1140/epjc/s10052-012-2003-4
2012
Cited 160 times
Updated status of the global electroweak fit and constraints on new physics
We present an update of the Standard Model fit to electroweak precision data. We include newest experimental results on the top quark mass, the W mass and width, and the Higgs boson mass bounds from LEP, Tevatron and the LHC. We also include a new determination of the electromagnetic coupling strength at the Z pole. We find for the Higgs boson mass (91 +30 -23) GeV and (120 +12 -5) GeV when not including and including the direct Higgs searches, respectively. From the latter fit we indirectly determine the W mass to be (80.360 +0.014 -0.013) GeV. We exploit the data to determine experimental constraints on the oblique vacuum polarisation parameters, and confront these with predictions from the Standard Model (SM) and selected SM extensions. By fitting the oblique parameters to the electroweak data we derive allowed regions in the BSM parameter spaces. We revisit and consistently update these constraints for a fourth fourth fermion generation, two Higgs doublet, inert Higgs and littlest Higgs models, models with large, universal or warped extra dimensions and technicolour. In most of the models studied a heavy Higgs boson can be made compatible with the electroweak precision data.
DOI: 10.1140/epjc/s10052-009-0966-6
2009
Cited 159 times
Revisiting the global electroweak fit of the Standard Model and beyond with Gfitter
The global fit of the Standard Model to electroweak precision data, routinely performed by the LEP electroweak working group and others, demonstrated impressively the predictive power of electroweak unification and quantum loop corrections. We have revisited this fit in view of (i) the development of the new generic fitting package, Gfitter, allowing for flexible and efficient model testing in high-energy physics, (ii) the insertion of constraints from direct Higgs searches at LEP and the Tevatron, and (iii) a more thorough statistical interpretation of the results. Gfitter is a modular fitting toolkit, which features predictive theoretical models as independent plug-ins, and a statistical analysis of the fit results using toy Monte Carlo techniques. The state-of-the-art electroweak Standard Model is fully implemented, as well as generic extensions to it. Theoretical uncertainties are explicitly included in the fit through scale parameters varying within given error ranges. This paper introduces the Gfitter project, and presents state-of-the-art results for the global electroweak fit in the Standard Model (SM), and for a model with an extended Higgs sector (2HDM). Numerical and graphical results for fits with and without including the constraints from the direct Higgs searches at LEP and Tevatron are given. Perspectives for future colliders are analysed and discussed. In the SM fit including the direct Higgs searches, we find M H =116.4 −1.3 +18.3 GeV, and the 2σ and 3σ allowed regions [114,145] GeV and [[113,168] and [180,225]] GeV, respectively. For the strong coupling strength at fourth perturbative order we obtain α S (M 2 )=0.1193 −0.0027 +0.0028 (exp )±0.0001 (theo). Finally, for the mass of the top quark, excluding the direct measurements, we find m t =178.2 −4.2 +9.8 GeV. In the 2HDM we exclude a charged-Higgs mass below 240 GeV at 95% confidence level. This limit increases towards larger tan β, e.g., $M_{H^{\pm}}<780\ \mbox{GeV}$ is excluded for tan β=70.
DOI: 10.1140/epjc/s10052-015-3511-9
2015
Cited 103 times
Physics at the $$e^+ e^-$$ e + e - linear collider
A comprehensive review of physics at an e+e- Linear Collider in the energy range of sqrt{s}=92 GeV--3 TeV is presented in view of recent and expected LHC results, experiments from low energy as well as astroparticle physics.The report focuses in particular on Higgs boson, Top quark and electroweak precision physics, but also discusses several models of beyond the Standard Model physics such as Supersymmetry, little Higgs models and extra gauge bosons. The connection to cosmology has been analyzed as well.
DOI: 10.1016/j.cpc.2005.12.009
2006
Cited 128 times
ZFITTER: a semi-analytical program for fermion pair production in <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si1.gif" overflow="scroll"><mml:msup><mml:mi>e</mml:mi><mml:mo>+</mml:mo></mml:msup><mml:msup><mml:mi>e</mml:mi><mml:mo>−</mml:mo></mml:msup></mml:math> annihilation, from version 6.21 to version 6.42
ZFITTER is a Fortran program for the calculation of fermion pair production and radiative corrections at high energy e+e- colliders; it is also suitable for other applications where electroweak radiative corrections appear. ZFITTER is based on a semi-analytical approach to the calculation of radiative corrections in the Standard Model. We present a summary of new features of the ZFITTER program version 6.42 compared to version 6.21. The most important additions are: (i) some higher-order QED corrections to fermion pair production, (ii) electroweak one-loop corrections to atomic parity violation, (iii) electroweak one-loop corrections to nu-e nu-e-bar production, (iv) electroweak two-loop corrections to the W boson mass and the effective weak mixing angle.
DOI: 10.1007/bf01565050
1993
Cited 68 times
A measurement of the ratio of the nucleon structure function in copper and deuterium
Results are presented on the ratios of the nucleon structure function in copper to deuterium from two separate experiments. The data confirm that the nucleon structure function,F 2, is different for bound nucleons than for the quasi-free ones in the deuteron. The redistribution in the fraction of the nucleon's momentum carried by quarks is investigated and it is found that the data are compatible with no integral loss of quark momenta due to nuclear effects.
2007
Cited 62 times
International Linear Collider Reference Design Report Volume 2: PHYSICS AT THE ILC
This article reviews the physics case for the ILC. Baseline running at 500 GeV as well as possible upgrades and options are discussed. The opportunities on Standard Model physics, Higgs physics, Supersymmetry and alternative theories beyond the Standard Model are described.
DOI: 10.2172/914731
2007
Cited 61 times
International Linear Collider Reference Design Report
{lg_bullet} What is the universe? How did it begin? {lg_bullet} What are matter and energy? What are space and time? These basic questions have been the subject of scientific theories and experiments throughout human history. The answers have revolutionized the enlightened view of the world, transforming society and advancing civilization. Universal laws and principles govern everyday phenomena, some of them manifesting themselves only at scales of time and distance far beyond everyday experience. Particle physics experiments using particle accelerators transform matter and energy, to reveal the basic workings of the universe. Other experiments exploit naturally occurring particles, such as solar neutrinos or cosmic rays, and astrophysical observations, to provide additional insights.
DOI: 10.1140/epjc/s10052-010-1244-3
2010
Cited 46 times
From the LHC to future colliders
Discoveries at the LHC will soon set the physics agenda for future colliders. This report of a CERN Theory Institute includes the summaries of Working Groups that reviewed the physics goals and prospects of LHC running with 10 to 300 fb−1 of integrated luminosity, of the proposed sLHC luminosity upgrade, of the ILC, of CLIC, of the LHeC and of a muon collider. The four Working Groups considered possible scenarios for the first 10 fb−1 of data at the LHC in which (i) a state with properties that are compatible with a Higgs boson is discovered, (ii) no such state is discovered either because the Higgs properties are such that it is difficult to detect or because no Higgs boson exists, (iii) a missing-energy signal beyond the Standard Model is discovered as in some supersymmetric models, and (iv) some other exotic signature of new physics is discovered. In the contexts of these scenarios, the Working Groups reviewed the capabilities of the future colliders to study in more detail whatever new physics may be discovered by the LHC. Their reports provide the particle physics community with some tools for reviewing the scientific priorities for future colliders after the LHC produces its first harvest of new physics from multi-TeV collisions.
2005
Cited 58 times
The role of polarized positrons and electrons in revealing fundamental interactions at the Linear Collider
The proposed International Linear Collider (ILC) is well-suited for discovering physics beyond the Standard Model and for precisely unraveling the structure of the underlying physics. The physics return can be maximized by the use of polarized beams. This report shows the paramount role of polarized beams and summarizes the benefits obtained from polarizing the positron beam, as well as the electron beam. The physics case for this option is illustrated explicitly by analyzing reference reactions in different physics scenarios. The results show that positron polarization, combined with the clean experimental environment provided by the linear collider, allows to improve strongly the potential of searches for new particles and the identification of their dynamics, which opens the road to resolve shortcomings of the Standard Model. The report also presents an overview of possible designs for polarizing both beams at the ILC, as well as for measuring their polarization.
DOI: 10.48550/arxiv.1307.5288
2013
Cited 34 times
Physics at the CLIC e+e- Linear Collider -- Input to the Snowmass process 2013
This paper summarizes the physics potential of the CLIC high-energy e+e- linear collider. It provides input to the Snowmass 2013 process for the energy-frontier working groups on The Higgs Boson (HE1), Precision Study of Electroweak Interactions (HE2), Fully Understanding the Top Quark (HE3), as well as The Path Beyond the Standard Model -- New Particles, Forces, and Dimensions (HE4). It is accompanied by a paper describing the CLIC accelerator study, submitted to the Frontier Capabilities group of the Snowmass process.
2000
Cited 56 times
Review of Particle Physics, 2000-2001
DOI: 10.1016/s0168-9002(98)00344-1
1998
Cited 49 times
The DELPHI Silicon Tracker at LEP2
The DELPHI Silicon Tracker, an ensemble of microstrips, ministrips and pixels, was completed in 1997 and has accumulated over 70pb−1 of high-energy data. The Tracker is optimised for the LEP2 physics programme. It consists of a silicon microstrip barrel and endcaps with layers of silicon pixel and ministrip detectors. In the barrel part, three-dimensional b tagging information is available down to a polar angle of 25°. Impact parameter resolutions have been measured of 28μm ⊕71/(psin3/2θ)μm in Rφ and 34μm ⊕69/pμm in Rz, where p is the track momentum in GeV/c. The amount of material has been kept low with the use of double-sided detectors, double-metal readout, and light mechanics. The pixels have dimensions of 330×330μm2 and the ministrips have a readout pitch of 200μm. The forward part of the detector shows average efficiencies of more than 96%, has signal-to-noise ratios of up to 40 in the ministrips, and noise levels at the level of less than one part per million in the pixels. Measurements of space points with low backgrounds are provided, leading to a vastly improved tracking efficiency for the region with polar angle less than 25°.
DOI: 10.1140/epjc/s10052-006-0038-0
2006
Cited 39 times
Determination of new electroweak parameters at the ILC – sensitivity to new physics
We present a study of the sensitivity of an International Linear Collider (ILC) to electroweak parameters in the absence of a light Higgs boson. In particular, we consider those parameters that have been inaccessible at previous colliders, quartic gauge couplings. Within a generic effective-field theory context we analyze all processes that contain quasi-elastic weak-boson scattering, using complete six-fermion matrix elements in unweighted event samples, fast simulation of the ILC detector, and a multidimensional parameter fit of the set of anomalous couplings. The analysis does not rely on simplifying assumptions such as custodial symmetry or approximations such as the equivalence theorem. We supplement this by a similar new study of triple weak-boson production, which is sensitive to the same set of anomalous couplings. Including the known results on triple gauge couplings and oblique corrections, we thus quantitatively determine the indirect sensitivity of the ILC to new physics in the electroweak symmetry-breaking sector, conveniently parameterized by real or fictitious resonances in each accessible spin/isospin channel.
DOI: 10.1007/bf01559431
1991
Cited 38 times
Forward produced hadrons in μp and μd scattering and investigation of the charge structure of the nucleon
Final data measured with the EMC forward spectrometer are presented on the production of forward charged hadrons in μp and μd scattering at incident beam energies between 100 and 280 GeV. The large statistic of 373 000 events allows a study of the semi-inclusive hadron production as a function ofz,p 2 and 〈p 2 〉 in smallQ 2,x Bj andW bins. Charge multiplicity ratios and differences as a function ofz andx Bj are given forp, d andn-targets. From the differences of charge multiplicities the ratio of the valence quark distributions of the protond v (x)/u v (x) is determined for the first time in charged lepton scattering. The Gronau et al. sum rule is tested, the measured sum being 0.31±0.06 stat. ±0.05 syst., compared with the theoretical expectation of 2/7≈0.286. The measured sum corresponds to an absolute value of the ratio of thed andu quark charge of 0.44±0.10 stat.±0.08 syst.
2008
Cited 28 times
The role of polarized positrons and electrons in revealing fundamental interactions at the Linear Collider
The proposed International Linear Collider (ILC) is well-suited for discovering physics beyond the Standard Model and for precisely unraveling the structure of the underlying physics. The physics return can be maximized by the use of polarized beams. This report shows the paramount role of polarized beams and summarizes the benefits obtained from polarizing the positron beam, as well as the electron beam. The physics case for this option is illustrated explicitly by analyzing reference reactions in different physics scenarios. The results show that positron polarization, combined with the clean experimental environment provided by the linear collider, allows to improve strongly the potential of searches for new particles and the identification of their dynamics, which opens the road to resolve shortcomings of the Standard Model. The report also presents an overview of possible designs for polarizing both beams at the ILC, as well as for measuring their polarization.
DOI: 10.1088/1748-0221/4/10/p10015
2009
Cited 26 times
Polarimeters and energy spectrometers for the ILC Beam Delivery System
Any future high energy e+e− linear collider aims at precision measurements of Standard Model quantities as well as of new, not yet discovered phenomena. In order to pursue this physics programme, excellent detectors at the interaction region have to be complemented by beam diagnostics of unprecedented precision. This article gives an overview of current plans and issues for polarimeters and energy spectrometers at the International Linear Collider, which have been designed to fulfill the precision goals at a large range of beam energies from 45.6 GeV at the Z0 pole up to 250 GeV or, as an upgrade, up to 500 GeV.
DOI: 10.48550/arxiv.1310.6708
2013
Cited 19 times
Study of Electroweak Interactions at the Energy Frontier
With the discovery of the Higgs boson, the spectrum of particles in the Standard Model (SM) is complete. It is more important than ever to perform precision measurements and to test for deviations from SM predictions in the electroweak sector. In this report, we investigate two themes in the arena of precision electroweak measurements: the electroweak precision observables (EWPOs) that test the particle content and couplings in the SM and the minimal supersymmetric SM, and the measurements involving multiple gauge bosons in the final state which provide unique probes of the basic tenets of electroweak symmetry breaking. Among the important EWPOs we focus our discussion on M_W and sin^2 theta_eff^l, and on anomalous quartic gauge couplings probed by triboson production and vector boson scattering. We investigate the thresholds of precision that need to be achieved in order to be sensitive to new physics. We study the precision that can be achieved at various facilities on these observables. We discuss the calculational tools needed to predict SM rates and distributions in order to perform these measurements at the required precision. This report summarizes the work of the Energy Frontier Precision Study of Electroweak Interactions working group of the 2013 Community Summer Study (Snowmass).
DOI: 10.22323/1.449.0304
2024
The global electroweak fit in the SM and SMEFT
We present results from the global electroweak fit to precision measurements of the Standard Model (SM). The fit uses the latest experimental results as well as up-to-date theoretical calculations for observables on the Z pole and the W boson mass, yielding precise SM predictions for the effective weak mixing angle and the masses of the W and Higgs bosons, as well as the top quark. We report constraints on coefficients of the SM effective field theory (SMEFT), obtained from electroweak precision data. We present correlations between the SMEFT coefficients, evaluated at next-to-leading order for the precision observables entering the fit, and the free parameters of the SM.
DOI: 10.1016/j.nima.2006.03.017
2006
Cited 29 times
Design study of an optical cavity for a future photon collider at ILC
Hard photons well above 100 GeV have to be generated in a future photon-collider which essentially will be based on the infrastructure of the planned International Linear Collider (ILC). The energy of near-infrared laser photons will be boosted by Compton backscattering against a high energy relativistic electron beam. For high effectiveness, a very powerful lasersystem is required that exceeds todays state-of-the-art capabilities. In this paper a design of an auxiliary passive cavity is discussed that resonantly enhances the peak-power of the laser. The properties and prospects of such a cavity are addressed on the basis of the specifications for the European TeV Energy Superconducting Linear Accelerator (TESLA) proposal. Those of the ILC are expected to be similar.
DOI: 10.48550/arxiv.1512.05194
2015
Cited 16 times
High-precision $α_s$ measurements from LHC to FCC-ee
This document provides a writeup of all contributions to the workshop on "High precision measurements of $α_s$: From LHC to FCC-ee" held at CERN, Oct. 12--13, 2015. The workshop explored in depth the latest developments on the determination of the QCD coupling $α_s$ from 15 methods where high precision measurements are (or will be) available. Those include low-energy observables: (i) lattice QCD, (ii) pion decay factor, (iii) quarkonia and (iv) $τ$ decays, (v) soft parton-to-hadron fragmentation functions, as well as high-energy observables: (vi) global fits of parton distribution functions, (vii) hard parton-to-hadron fragmentation functions, (viii) jets in $e^\pm$p DIS and $γ$-p photoproduction, (ix) photon structure function in $γ$-$γ$, (x) event shapes and (xi) jet cross sections in $e^+e^-$ collisions, (xii) W boson and (xiii) Z boson decays, and (xiv) jets and (xv) top-quark cross sections in proton-(anti)proton collisions. The current status of the theoretical and experimental uncertainties associated to each extraction method, the improvements expected from LHC data in the coming years, and future perspectives achievable in $e^+e^-$ collisions at the Future Circular Collider (FCC-ee) with $\cal{O}$(1--100 ab$^{-1}$) integrated luminosities yielding 10$^{12}$ Z bosons and jets, and 10$^{8}$ W bosons and $τ$ leptons, are thoroughly reviewed. The current uncertainty of the (preliminary) 2015 strong coupling world-average value, $α_s(m_Z)$ = 0.1177 $\pm$ 0.0013, is about 1\%. Some participants believed this may be reduced by a factor of three in the near future by including novel high-precision observables, although this opinion was not universally shared. At the FCC-ee facility, a factor of ten reduction in the $α_s$ uncertainty should be possible, mostly thanks to the huge Z and W data samples available.
2001
Cited 30 times
TESLA: The Superconducting electron positron linear collider with an integrated x-ray laser laboratory. Technical design report. Part 3. Physics at an e+ e- linear collider
DOI: 10.1103/revmodphys.68.611
1996
Cited 28 times
<b>PARTICLE PHYSICS SUMMARY</b>A Digest of the<i>1996 Review of Particle Physics</i>
This report summarizes the highlights of the 1996 {ital Review} {ital of} {ital Particle} {ital Physics} (Phys. Rev. D {bold 54}, 1 (1996)). Using data from previous editions, plus 1900 new measurements from 700 papers, we list, evaluate, and average measured properties of gauge bosons, leptons, quarks, mesons, and baryons. We summarize searches for hypothetical particles such as Higgs bosons, heavy neutrinos, and supersymmetric particles. We also give numerous reviews, tables, figures, and formulae. The present edition marks the apparent completion of the table of Standard Model quarks with the discovery of the top. A booklet is available containing the Summary Tables and abbreviated versions of some of the other sections of the full {ital Review}. {copyright} {ital 1996 The American Physical Society.}
DOI: 10.1007/bf01550991
1988
Cited 26 times
Exclusive ρ0 and Φ production in deep inelastic muon scattering
Data are presented on exclusive ρ0 and ϕ production in deep inelastic muon scattering from a target consisting mainly of nitrogen. The ratio of the total cross sections for ρ0 and ϕ production is found to be 9∶(1.6±0.4) at 〈Q 2〉=7.5 GeV2, consistent with theSU(3) prediction of 9∶2. Thet dependence for exclusive ρ0 production is found to become shallover asQ 2 increases and, for largeQ 2, thet dependence is typical of that for a hard scattering process. Furthermore, the ratio of the cross sections for coherent: incoherent production from nitrogen is found to decrease rapidly withQ 2. Such behaviour indicates that even for exclusive vector meson production the virtual photon behaves predominantly as an electromagnetic probe.
DOI: 10.1007/s100529800890
1998
Cited 27 times
QCD corrections to the forward-backward asymmetries of c and b quarks at the Z pole
DOI: 10.1016/s0168-9002(96)01089-3
1997
Cited 26 times
The DELPHI pixels
To improve tracking in the very forward direction for running at LEP200, the angular acceptance of the DELPHI Vertex detector has been extended from 45° to 11° with respect to the beam axis. Pixel detector crowns cover the region between 25° and 13°. Due to very tight space and material thickness constraints it was necessary to develop new techniques (integrated busses in the detector substrate, high density layout on Kapton, etc.). About 1000 cm2 of pixels are already installed and working in DELPHI. Techniques, tests and production of these detectors will be described, as well as the main problems encountered during this work.
DOI: 10.1016/j.nima.2006.04.042
2006
Cited 20 times
Studies for a photon collider at the ILC
One option at the International Linear Collider is to convert the electron beams into high energy photon beams by Compton scattering a few millimetres in front of the interaction region. Selected physics channels for this option have been analysed and technical issues have been studied. So far no showstoppers for this option have been found.
DOI: 10.1140/epjc/s10052-011-1718-y
2011
Cited 14 times
Erratum to: Revisiting the global electroweak fit of the Standard Model and beyond with Gfitter
The global fit of the Standard Model to electroweak precision data, routinely performed by the LEP electroweak working group and others, demonstrated impressively the predictive power of electroweak unification and quantum loop corrections. We have revisited this fit in view of (i) the development of the new generic fitting package Gfitter, (ii) the insertion of constraints from direct Higgs searches at LEP and the Tevatron, and (iii) a more thorough statistical interpretation of the results. Gfitter is a modular fitting toolkit, which features predictive theoretical models as independent plugins, and a statistical analysis of the fit results using toy Monte Carlo techniques. The state-of-the-art electroweak Standard Model is fully implemented, as well as generic extensions to it. This paper introduces the Gfitter project, and presents state-of-the-art results for the global electroweak fit in the Standard Model, and for a model with an extended Higgs sector (2HDM). Numerical and graphical results for fits with and without including the constraints from the direct Higgs searches at LEP and Tevatron are given. Perspectives for future colliders are analysed and discussed. Including the direct Higgs searches, we find M_H=(116.4 +18.3 -1.3) GeV, and the 2sigma and 3sigma allowed regions [114,145] GeV and [[113,168] and [180,225]] GeV, respectively. For the strong coupling strength at fourth perturbative order we obtain alpha_S(M_Z)=0.1193 +0.0028 -0.0027(exp) +- 0.0001(theo). Finally, for the mass of the top quark, excluding the direct measurements, we find m_t=(178.2 +9.8 -4.2) GeV. In the 2HDM we exclude a charged-Higgs mass below 240 GeV at 95% confidence level. This limit increases towards larger tan(beta), where e.g., M_H+-<780 GeV is excluded for tan(beta)=70.
2013
Cited 12 times
Working Group Report: Precision Study of Electroweak Interactions
With the discovery of the Higgs boson, the spectrum of particles in the Standard Model (SM) is complete. It is more important than ever to perform precision measurements and to test for deviations from SM predictions in the electroweak sector. In this report, we investigate two themes in the arena of precision electroweak measurements: the electroweak precision observables (EWPOs) that test the particle content and couplings in the SM and the minimal supersymmetric SM, and the measurements involving multiple gauge bosons in the final state which provide unique probes of the basic tenets of electroweak symmetry breaking. Among the important EWPOs we focus our discussion on M_W and sin^2 theta_eff^l, and on anomalous quartic gauge couplings probed by triboson production and vector boson scattering. We investigate the thresholds of precision that need to be achieved in order to be sensitive to new physics. We study the precision that can be achieved at various facilities on these observables. We discuss the calculational tools needed to predict SM rates and distributions in order to perform these measurements at the required precision. This report summarizes the work of the Energy Frontier Precision Study of Electroweak Interactions working group of the 2013 Community Summer Study (Snowmass).
DOI: 10.1088/1748-0221/2/09/p09001
2007
Cited 16 times
Impact of beam-beam effects on precision luminosity measurements at the ILC
In this paper, the impact of beam-beam effects on the precision luminosity measurement at the International Linear Collider is investigated quantitatively for the first time. GUINEA-PIG, a beam-beam interaction simulation tool, is adapted to treat the space charge effects affecting the Bhabha events used in this measurement. The biases due to the resulting changes in kinematics are evaluated for different center-of-mass energies and beam parameters.
DOI: 10.5170/cern-1996-001-v-1.207
1996
Cited 16 times
Standard model processes
DOI: 10.1140/epjc/s2005-02164-6
2005
Cited 11 times
Corrections to quark asymmetries at LEP
The most precise measurement of the weak mixing angle $\sin^2 \theta_{\mathrm{eff}}^l$ at LEP is from the forward-backward asymmetry $e^ + e^- \rightarrow b \overline{b}$ at the Z-pole. In this note the QED and electroweak radiative corrections to obtain the pole asymmetry from the measured asymmetry for b- and c-quarks have been calculated using ZFITTER, which has been amended to allow a consistent treatment of partial two-loop corrections for the b-quark final asymmetries. A total correction of $\delta A_{\mathrm{FB}}^{{b}} = 0.0019 \pm 0.0002$ and $\delta A_{\mathrm{FB}}^{{c}} = 0.0064 \pm 0.0001$ has been found, where the remaining theoretical uncertainty is much too small to explain the apparent discrepancy between $\sin^2 \theta_{\mathrm{eff}}^l$ obtained from A FB b and from the left-right asymmetry at SLD.
DOI: 10.1140/epjc/s2005-02310-2
2005
Cited 9 times
Studies on chargino production and decay at a photon collider
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 $ \gamma \gamma \to \tilde{\chi }^{ + }_{1} \tilde{\chi }^{ - }_{1} \to W^{ + } W^{ - } \tilde{\chi }^{0}_{1} \tilde{\chi }^{0}_{1} \to q\bar{q}q\bar{q}\tilde{\chi }^{0}_{1} \tilde{\chi }^{0}_{1} % $ 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( ${\tilde{\chi}_1^\pm}\rightarrow {\tilde{\chi}_1^0} W^\pm$ ) of up to 3.5% can be reached.
DOI: 10.1016/0168-9002(95)00541-2
1995
Cited 13 times
The DELPHI very forward tracker for LEP200
The design of a new silicon tracker detector for the forward region in the DELPHI experiment is presented. It consists of two layers of macropixel and two layers of ministrip detectors in both the forward directions. The motivations and the requirements for this detector will be shown together with test beam results.
DOI: 10.1007/bf01589703
1992
Cited 12 times
Muoproduction ofJ/ψ and the gluon distribution of the nucleon
Measurements are presented of the inclusive distributions of theJ/Ψ meson produced by muons of energy 200 GeV from an ammonia target. The gluon distribution of the nucleon has been derived from the data in the range 0.04<x<0.36 using a technique based on the colour singlet model. An arbitrary normalisation factor is required to obtain a reasonable integral of the gluon distribution. Some comments are made on the use ofJ/Ψ productionby virtual photons to extract the gluon distribution at HERA.
DOI: 10.1103/physrevstab.9.034402
2006
Cited 8 times
Incoherent pair generation in a beam-beam interaction simulation
This paper deals with two topics: the generation of incoherent pairs in two beam-beam simulation programs, GUINEA-PIG and CAIN, and the influence of the International Linear Collider (ILC) beam parameter choices on the background in the micro--vertex detector (VD) induced by direct hits. One of the processes involved in incoherent pair creation (IPC) is equivalent to a four fermions interaction and its cross section can be calculated exactly with a dedicated generator, BDK. A comparison of GUINEA-PIG and CAIN results with BDK allows to identify and quantify the uncertainties on IPC background predictions and to benchmark the GUINEA-PIG calculation. Based on this simulation and different VD designs, the five currently suggested ILC beam parameter sets have been compared regarding IPC background induced in the VD by direct IPC hits. We emphasize that the high luminosity set, as it is currently defined, would constrain both the choices of magnetic field and VD inner layer radius.
DOI: 10.48550/arxiv.0808.1638
2008
Cited 6 times
Executive Summary of the Workshop on Polarisation and Beam Energy Measurements at the ILC
This note summarizes the results of the "Workshop on Polarisation and Beam Energy Measurements at the ILC", held at DESY (Zeuthen) April 9-11 2008. The topics for the workshop included (i) physics requirements, (ii) polarised sources and low energy polarimetry, (iii) BDS polarimeters, (iv) BDS energy spectrometers, and (v) physics-based measurements of beam polarisation and beam energy from collider data. Discussions focused on the current ILC baseline programme as described in the Reference Design Report (RDR), which includes physics runs at beam energies between 100 and 250 GeV, as well as calibration runs on the Z-pole. Electron polarisation of P_e- &gt;~ 80% and positron polarisation of P_e+ &gt;~ 30% are part of the baseline configuration of the machine. Energy and polarisation measurements for ILC options beyond the baseline, including Z-pole running and the 1 TeV energy upgrade, were also discussed.
DOI: 10.1016/s0168-9002(96)01233-8
1997
Cited 11 times
Progress in the construction of the DELPHI pixel detector
The status of the pixel detector for the DELPHI Silicon Tracker is presented. The main characteristics of the detector, the readout chip and the assembly are summarized.
DOI: 10.1063/1.2888124
2008
Cited 5 times
ILC Positron Source Based on Laser Compton
Positron generation is one of the most difficult technical challenges among the ILC (International Linear Collider) subsystems. A positron source based on Laser Compton back scattering is an attractive and advanced option for the ILC positron source. Here, the positrons are generated, via the pair creation process, from high energy gamma rays which themselves are produced by Compton scattering of laser photons off a high‐energy electron beam. Polarized positrons can be generated by employing a circularly polarized laser. The positron polarization is easily controlled and switched by changing the laser polarity. The electron beam can be unpolarized. The required electron energy is only a few GeV (in contrast, the “undulator scheme”, another advanced option, requires at least 100 GeV or more) and the system can be prototyped and tested prior to the real construction. The laser Compton technology has many other applications like advanced X‐ray sources and a good synergy is expected. In addition, this technology can be a powerful driving force for the ILC project attracting many researchers from outside the ILC community. The ILC positron source is a technical challenge and it will be realized only if the latest technologies are integrated seamlessly with the necessary R&D efforts for system specific issues. The latest technologies include high power lasers, high brightness electron beams, high finesse optical cavities for as laser‐beam interaction point, etc. We present the design status and the related experimental efforts for the ILC positron source based on Laser Compton scattering. The respective advantages of various options for the electron beam (based on Linac, storage ring, and ERL) are also compared.
DOI: 10.22323/1.414.0897
2022
Status of the global electroweak fit with Gfitter in the light of new precision measurements
We present results from the global electroweak fit to precision measurements in the Standard Model (SM).The fit uses the latest theoretical calculations for observables on the pole and the boson mass, yielding precise SM predictions for the effective weak mixing angle and the masses of the and Higgs bosons, as well as the top quark.We study the impact of the latest measurements on the fit and provide comparisons of the resulting predictions for individual observables with recent measurements.
DOI: 10.1016/s0168-9002(98)00712-8
1998
Cited 10 times
Commissioning of the DELPHI Pixel Detector
The DELPHI Vertex Detector has been upgraded for LEP200 with 2 layers of pixel detectors and 2 layers of ministrips as endcaps, thus covering the polar angular range between 10° and 21° and allowing for standalone pattern recognition. During the 1995/96 shutdown the first 95 modules were installed and the installation was completed in May 97 with all 152 modules. Production yields and failures during the assembly will be presented. The detector operated at a threshold of around 9000 electrons resulting in a number of noisy pixels at the 10−3 level. After masking these hot pixels in the readout, the remaining number of random hits per event is at the 10−6 level. The observed resolution of about 100 μm is close to the expectation for binary readout. The track reconstruction efficiency increased by more than 100% in the central part of the forward tracker.
DOI: 10.1088/0034-4885/61/8/002
1998
Cited 10 times
Status of electroweak tests with heavy quarks
The measurements of the partial decay widths and forward-backward asymmetries for and test the Z-couplings to the initial state -pair and the heavy quarks in the final state.
DOI: 10.1007/s1010599c0008
2000
Cited 9 times
Electroweak and CP violation physics at a Linear Collider Z-factory
A future linear collider such as TESLA may be able to run on the Z0 resonance with very high luminosity and polarised electron and positron beams. The possibilities of measuring electroweak quantities with high precision are investigated. Huge improvements with respect to the present precision can be expected, especially for the asymmetries ALR and $${\cal A}_{\rm b}$$ where beam polarisation can be exploited. The very large sample of $${\rm Z}^0 \to b{\bar b}$$ events also allows studies of various CP-violating b decays. The precision achievable on the CKM unitarity triangle angles is comparable to experiments at b factories and future hadron colliders.
DOI: 10.1103/physrevstab.9.094001
2006
Cited 6 times
Beam dynamics in Compton ring gamma sources
Electron storage rings of GeV energy with laser pulse stacking cavities are promising intense sources of polarized hard photons which, via pair production, can be used to generate polarized positron beams. In this paper, the dynamics of electron bunches circulating in a storage ring and interacting with high-power laser pulses is studied both analytically and by simulation. Both the common features and the differences in the behavior of bunches interacting with an extremely high power laser pulse and with a moderate pulse are discussed. Also considerations on particular lattice designs for Compton gamma rings are presented.
DOI: 10.1140/epjc/s2004-02091-0
2005
Cited 5 times
Measurement of triple gauge boson couplings at an $e\gamma$ -collider
If no light Higgs boson exists, the interaction among the gauge bosons becomes strong at high energies (~1TeV). The effects of strong electroweak symmetry breaking (SEWSB) could manifest themselves indirectly as anomalous couplings before they give rise to new physical states like resonances. Here a study of the measurement of trilinear gauge couplings is presented looking at the hadronic decay channel of the W boson at an e-gamma - collider. A sensitivity in the range of 10^{-3} to 10^{-4} can be reached depending on the coupling under consideration.
DOI: 10.2172/825067
2003
Cited 5 times
Undulator-Based Production of Polarized Positrons, A Proposal for the 50-GeV Beam in the FFTB
The full exploitation of the physics potential of future linear colliders such as the JLC, NLC, and TESLA will require the development of polarized positron beams. In the proposed scheme of Balakin and Mikhailichenko [1] a helical undulator is employed to generate photons of several MeV with circular polarization which are then converted in a relatively thin target to generate longitudinally polarized positrons. This experiment, E-166, proposes to test this scheme to determine whether such a technique can produce polarized positron beams of sufficient quality for use in future linear colliders. The experiment will install a meter-long, short-period, pulsed helical undulator in the Final Focus Test Beam (FFTB) at SLAC. A low-emittance 50-GeV electron beam passing through this undulator will generate circularly polarized photons with energies up to 10 MeV. These polarized photons are then converted to polarized positrons via pair production in thin targets. Titanium and tungsten targets, which are both candidates for use in linear colliders, will be tested. The experiment will measure the flux and polarization of the undulator photons, and the spectrum and polarization of the positrons produced in the conversion target, and compare the measurement results to simulations. Thus the proposed experiment directly tests for the first time the validity of the simulation programs used for the physics of polarized pair production in finite matter, in particular the effects of multiple scattering on polarization. Successful comparison of the experimental results to the simulations will lead to greater confidence in the proposed designs of polarized positrons sources for the next generation of linear colliders. This experiment requests six-weeks of time in the FFTB beam line: three weeks for installation and setup and three weeks of beam for data taking. A 50-GeV beam with about twice the SLC emittance at a repetition rate of 30 Hz is required.
DOI: 10.1140/epjc/s10052-008-0765-5
2008
Cited 3 times
Towards a measurement of the two-photon decay width of the Standard Model Higgs boson at a Photon Collider
A study of the measurement of the two photon decay width times the branching ratio of the Standard Model Higgs boson with a mass of 120 GeV in photon–photon collisions is presented, assuming a γ γ integrated luminosity of 80 fb−1 in the high energy part of the spectrum. The analysis is based on the reconstruction of the Higgs events produced in the γ γ→H process, followed by the decay of the Higgs into a $\mathrm{b}\bar{\mathrm{b}}$ pair. A statistical error of the measurement of the two-photon width, Γ(H→γ γ), times the branching ratio of the Higgs boson, BR $(\mathrm{H}\to \mathrm{b}\bar{\mathrm{b}})$ is found to be 2.1% for one year of data taking.
2007
Cited 3 times
International linear collider reference design report volume 2: physics at the ILC
This article reviews the physics case for the ILC. Baseline running at 500 GeV as well as possible upgrades and options are discussed. The opportunities on Standard Model physics, Higgs physics, Supersymmetry and alternative theories beyond the Standard Model are described.
DOI: 10.1007/s100520050196
1998
Cited 7 times
QCD corrections to the forward-backward asymmetries of
Measurements of the forward-backward production asymmetry of heavy quarks in Z decays provide a precise determination of $\sin^2\!\theta_{\rm{W,eff}}^{\rm{lept}}$ . The asymmetries are sensitive to QCD effects, in particular hard gluon radiation. In this paper QCD corrections for $A_{\mathrm{FB}}^{{b\bar{b}}}$ and $A_{\mathrm{FB}}^{{c\bar c}}$ are discussed. The interplay between the experimental techniques used to measure the asymmetries and the QCD effects is investigated using simulated events. A procedure to estimate the correction needed for experimental measurements is proposed, and some specific examples are given.
DOI: 10.1016/j.physletb.2004.06.007
2004
Cited 4 times
Gauge &amp; Higgs boson summary table
DOI: 10.1016/s0168-9002(97)01267-9
1998
Cited 6 times
First results from the DELPHI pixel detector
In 1996 the DELPHI experiment at LEP has upgraded its silicon tracker. In the forward region, pixel detectors were installed. The pixel commissioning and the first results are reported.
DOI: 10.1134/s1547477109030017
2009
On pair production of scalar top quarks in e + e − collisions at ILC and a possibility of their mass reconstruction
We study pair production of scalar top quarks (stop, $$ \tilde t_1 $$ ) in e + e − collisions with the subsequent decay of the top squarks into b quarks and charginos $$ \tilde t_1 \to b\tilde \chi _1^ \pm $$ . We simulate this process by using PYTHIA6.4 for the beam energy 2E b = $$ \sqrt 2 $$ = 350, 400, 500, 800, 1000 GeV. A set of criteria for physical variables is proposed, which provides 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 with an integrated luminosity of 1000 fb−1 provided that the neutralino mass is known.
DOI: 10.1016/j.physletb.2008.07.018,
2008
Review of Particle Physics, 2008-2009
DOI: 10.48550/arxiv.2211.07665
2022
Status of the global electroweak fit with Gfitter in the light of new precision measurements
We present results from the global electroweak fit to precision measurements in the Standard Model (SM). The fit uses the latest theoretical calculations for observables on the $Z$ pole and the $W$ boson mass, yielding precise SM predictions for the effective weak mixing angle and the masses of the $W$ and Higgs bosons, as well as the top quark. We study the impact of the latest measurements on the fit and provide comparisons of the resulting predictions for individual observables with recent measurements.
DOI: 10.1007/s100529801043
1999
Cited 5 times
Search for scalar fermions and long-lived scalar leptons at centre-of-mass energies of 130 GeV to 172 GeV
Data taken by DELPHI during the 1995 and 1996 LEP runs have been used to search for the supersymmetric partners of electron, muon and tau leptons and of top and bottom quarks. The observations are in agreement with standard model predictions. Limits are set on sfermion masses. Searches for long lived scalar leptons from low scale supersymmetry breaking models exclude stau masses below 55 GeV/c2 at the 95% confidence level, irrespective of the gravitino mass.
2001
Cited 4 times
A Combination of Preliminary Electroweak Measurements and Constraints on the Standard Model, 2001. Prepared for the 2000 summer conferences
2001
Cited 3 times
TESLA: The superconducting electron positron linear collider with an integrated X-ray laser laboratory. Technical design report. Pt. 4: A detector for TESLA
DOI: 10.1063/1.1394301
2001
Cited 3 times
What is the case for a return to the Z-pole?
The possibilities to run with a linear collider at the Z-pole with high luminosity are examined. Apart from the implications on machine and detector the interest for electroweak and B-physics is discussed.
DOI: 10.2172/839900
2005
A Combination of Preliminary Electroweak Measurements And Constraints on the Standard Model (2004)
This note presents a combination of published and preliminary electroweak results from the four LEP collaborations and the SLD collaboration which were prepared for the 2004 summer conferences. Averages from Z resonance results are derived for hadronic and leptonic cross sections, the leptonic forward-backward asymmetries, the {tau} polarization asymmetries, the b{bar b} and c{bar c} partial widths and forward-backward asymmetries and the q{bar q} charge asymmetry. Above the Z resonance, averages are derived for di-fermion cross sections and forward-backward asymmetries, photon-pair, W-pair, Z-pair, single-W and single-Z cross sections, electroweak gauge boson couplings, W mass and width and W decay branching ratios. Also, an investigation of the interference of photon and Z-boson exchange is presented, and colour reconnection and Bose-Einstein correlation analyses in W-pair production are combined. The main changes with respect to the experimental results presented in summer 2003 are updates to the W branching fractions and four-fermion cross sections measured at LEP-2, and the SLD/LEP heavy-flavour results measured at the Z pole. The results are compared with precise electroweak measurements from other experiments, notably the final result on the electroweak mixing angle determined in neutrino-nucleon scattering by the NuTeV collaboration, the latest result in atomic parity violation in Caesium, and the measurement of the electroweak mixing angle in Moller scattering. The parameters of the Standard Model are evaluated, first using the combined LEP electroweak measurements, and then using the full set of high-Q{sup 2} electroweak results.
DOI: 10.1103/physics.3.14
2010
First bounds on the Higgs boson from hadron colliders
The two experimental collaborations at the Fermilab Tevatron accelerator have published first results of searches for the Higgs boson, excluding parts of the otherwise allowed mass range.
2002
Cited 3 times
Present and future electroweak precision measurements and the indirect determination of the mass of the Higgs boson
We discuss the experimental and theoretical uncertainties on precision electroweak observables and their relationship to the indirect constraints on the Higgs-boson mass, $\MH$, in the Standard Model (SM). The critical experimental measurements ($\MW$, $\sweff$, $\mt$, ...) are evaluated in terms of their present uncertainties and their prospects for improved precision at future colliders, and their contribution to the constraints on $\MH$. In addition, the current uncertainties of the theoretical predictions for $\MW$ and $\sweff$ due to missing higher order corrections are estimated and expectations and necessary theoretical improvements for future colliders are explored. The constraints from rare B decays are also discussed. Analysis of the present experimental and theoretical precisions yield a current upper bound on $\MH$ of $\sim 200$ GeV. Including anticipated improvements corresponding to the prospective situation at future colliders (Tevatron Run II, LHC, LC/GigaZ), we find a relative precision of about 25% to 8% (or better) is achievable in the indirect determination of $\MH$.
DOI: 10.1140/epjcd/s2003-01-011-7
2003
Measuring the luminosity of a γ γ collider with $\ensuremath\gamma \gamma \rightarrow \ell^+ \ell^- \gamma$ events
The process $\ensuremath\gamma \gamma \rightarrow \ell^+ \ell^-$ is highly suppressed when the total angular momentum of the two colliding photons is zero so that it cannot be used for luminosity determination. This configuration, however is needed for Higgs production at a photon collider. It will be shown that the process $\ensuremath\gamma \gamma \rightarrow \ell^+ \ell^- \gamma$ can be used in this case to measure the luminosity of a collider with a precision that is good enough not to limit the error on the partial decay width $\ensuremath\Gamma( {\rm H} \rightarrow \gamma \gamma)$ .
DOI: 10.48550/arxiv.0804.1700
2008
Pair production of scalar top quarks in polarized photon-photon collisions at ILC
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.
DOI: 10.48550/arxiv.0804.2125
2008
"Pair production of scalar top quarks in e+e- collisions at ILC."
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.
DOI: 10.48550/arxiv.0903.2959
2009
Beam Polarization at the ILC: the Physics Impact and the Accelerator Solutions
In this contribution accelerator solutions for polarized beams and their impact on physics measurements are discussed. Focus are physics requirements for precision polarimetry near the interaction point and their realization with polarized sources. Based on the ILC baseline programme as described in the Reference Design Report (RDR), recent developments are discussed and evaluated taking into account physics runs at beam energies between 100 GeV and 250 GeV, as well as calibration runs on the Z-pole and options as the 1TeV upgrade and GigaZ.
2009
Beam Polarization at the ILC: the Physics Impact and the Accelerator Solutions
In this contribution accelerator solutions for polarized beams and their impact on physics measurements are discussed. Focus are physics requirements for precision polarimetry near the interaction point and their realization with polarized sources. Based on the ILC baseline programme as described in the Reference Design Report (RDR), recent developments are discussed and evaluated taking into account physics runs at beam energies between 100 GeV and 250 GeV, as well as calibration runs on the Z-pole and options as the 1TeV upgrade and GigaZ.
DOI: 10.1109/pac.2007.4439932
2007
Bias on absolute luminosity measurements at the ILC from beam-beam space charge effects
This note summarizes the results of the first study done to quantify the impact of beam-beam effects on the precision luminosity measurement at the International Linear Collider, using GUINEA-PIG, a beam-beam interaction simulation tool <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</sup> .
DOI: 10.1142/s0217751x06032915
2006
PHYSICS AT FUTURE LINEAR COLLIDERS
This article summarises the physics at future linear colliders. It will be shown that in all studied physics scenarios a 1 TeV linear collider in addition to the LHC will enhance our knowledge significantly and helps to reconstruct the model of new physics nature has chosen.
2005
Polarization Setup and Polarimetry for 2 IRs, and Status of Downstream Polarimeter Designs
A spin rotation scheme for the International Linear Collider (ILC) is presented that allows the polarization spin vector to be tuned independently for different Interaction Regions (IR). A scheme to allow rapid helicity switching for polarized positrons is discussed. Comments on the downstream polarimeter designs are given.
2004
Corrections to quark asymmetries at LEP
The most precise measurement of the weak mixing angle sin{sup 2} {theta}{sub eff}{sup l} at LEP is from the forward-backward asymmetry e{sup +}e{sup -} {yields} b{bar b} at the Z-pole. In this note the QED and electroweak radiative corrections to obtain the pole asymmetry from the measured asymmetry for b- and c-quarks have been calculated using ZFITTER, which has been amended to allow a consistent treatment of partial two-loop corrections for the b-quark final asymmetries. A total correction of {delta}A{sub FB}{sup b} = 0.0019 {+-} 0.0002 and {delta}A{sub FB}{sup c} = 0.0064 {+-} 0.0001 has been found, where the remaining theoretical uncertainty is much too small to explain the apparent discrepancy between sin{sup 2} {theta}{sub eff}{sup l} obtained from A{sub FB}{sup b} and from the left-right asymmetry at SLD.
DOI: 10.1142/9789814733519_0012
2016
Global Fits of the Electroweak Standard Theory: Past, Present and Future
The last decades have seen tremendous progress in the experimental techniques for measuring key observables of the Standard Theory (ST) as well as in theoretical calculations that has led to highly precise predictions of these observables.Global electroweak fits of the ST compare the precision measurements of electroweak observables from lepton and hadron colliders at CERN and elsewhere with accurate theoretical predictions of the ST calculated at multi-loop level.For a long time, global fits have been used to assess the validity of the ST and to constrain indirectly (by exploiting contributions from quantum loops) the remaining free ST parameters, like the masses of the top quark and Higgs boson before their direct discovery.With the discovery of the Higgs boson at the Large Hadron Collider (LHC), the electroweak sector of the ST is now complete and all fundamental ST parameters are known.Hence the global fits are a powerful tool to probe the internal consistency of the ST, to predict ST parameters with high precision, and to constrain theories describing physics beyond the ST.In this chapter we review the global fits of the electroweak sector of the ST from an experimentalist's perspective.We briefly recall the most important achievements from the past (mainly driven by the precise measurements of Z pole observables), discuss the present situation after the accurate measurements of the top quark and Higgs boson masses, and present prospects of the fits as expected from new measurements at the LHC and future lepton colliders.
DOI: 10.22323/1.234.0100
2016
The global electroweak fit at NNLO and constraints on new physics
2015
Proceedings, High-Precision $\alpha_s$ Measurements from LHC to FCC-ee : Geneva, Switzerland, October 2-13, 2015
2001
Positron polarisation and low energy running at a Linear Collider
The physics potential of an e+e- linear collider can be significantly enhanced if both the electron and positron beams are polarised. Low energy running at the Z-resonance or close to the W-pair threshold is particularly attractive with polarised positrons. This note discusses the experimental aspects and physics opportunities of both low energy running and positron polarisation.
DOI: 10.1002/9783527634965.ch3
2011
Electroweak and Standard Model Tests: the Quest for Precision
This chapter contains sections titled: The Standard Model at Born Level The Gain from Additional Precision Measurements Constraints from Precision Data References
DOI: 10.1134/s1547477112010037
2012
Scalar top quarks production in polarized photon-photon collisions at ILC
DOI: 10.1016/s0920-5632(95)80046-8
1995
The design of silicon ministrip detectors for the DELPHI very forward tracker
The DELPHI Very Forward Tracker will extend the tracking capabilities of the DELPHI microvertex detector in the forward region. It consists of 4 cones of pixel and silicon strip detectors with large strip pitch. The silicon ministrip detector is optimized for high track reconstruction efficiency and momentum resolution at a minimum number of electronic channels. The properties of silicon strip detectors with large strip pitch in terms of charge collection and spatial resolution were investigated.
DOI: 10.1016/s0920-5632(02)90045-9
2002
The physics goals of the TESLA project
As next generation e+e− linear collider the superconducting accelerator project TESLA has been proposed. In this note the physics potential goals of this project, which is highly complementary to LHC, are described.
DOI: 10.1088/0954-3899/26/5/307
2000
Electroweak physics, experimental aspects
Collider measurements on electroweak physics are summarized. Although the precision on some observables is very high, no deviation from the standard model of electroweak interactions is observed. The data allow us to set stringent limits on some models for new physics.
2010
Viewpoint: First bounds on the Higgs boson from hadron colliders
The two experimental collaborations at the Fermilab Tevatron accelerator have published first results of searches for the Higgs boson, excluding parts of the otherwise allowed mass range.
2009
Beam polarization at the ILC. The physics impact and the accelerator solutions
In this contribution accelerator solutions for polarized beams and their impact on physics measurements are discussed. Focus are physics requirements for precision po-larimetry near the interaction point and their realization with polarized sources. Based on the ILC baseline programme as described in the Reference Design Report (RDR), recent developments are discussed and evaluated taking into account physics runs at beam energies between 100 GeV and 250 GeV, as well as calibration runs on the Z-pole and options as the 1TeV upgrade and GigaZ.
2009
On pair production of scalar top quarks in e+e- collisions at ILC and a possibility of their mass reconstruction
DOI: 10.1515/9783110211559.1.3.453
2008
DOI: 10.1515/9783110211559.1.3.655
2008
DOI: 10.1515/9783110211559.1.3.487
2008
DOI: 10.1007/s12043-007-0174-6
2007
Forward tracking detectors
DOI: 10.1007/s12043-007-0251-x
2007
Detector issues for a photon collider
DOI: 10.1007/s12043-007-0256-5
2007
Physics issues on triggering
2007
Impact of beam-beam effects on precision luminosity measurements at the ILC : main results