Searcharxiv⌕ Search

arXiv subjects

U. Baur

Publications and source records attributed to U. Baur.

At least 37 records · Page 2Linked to original sources
arXiv2003

Probing the Higgs self-coupling at hadron colliders using rare decays

We investigate Higgs boson pair production at hadron colliders for Higgs boson masses m_H\leq 140 GeV and rare decay of one of the two Higgs bosons. While in the Standard Model the number of events is quite low at the LHC, a first, albeit not very precise, measurement of the Higgs self-coupling is possible in the gg -> HH -> b\bar{b}γγchannel. A luminosity-upgraded LHC could improve this measurement considerably. A 200 TeV VLHC could make a measurement of the Higgs self-coupling competitive with a next-generation linear collider. In the MSSM we find a significant region with observable Higgs pair production in the small \tanβregime, where resonant production of two light Higgs bosons might be the only hint at the LHC of an MSSM Higgs sector.

hep-ph↗
arXiv2003

Measuring the W Boson Mass at Hadron Colliders

We discuss the prospects for measuring the W mass in Run II of the Tevatron and at the LHC. The basic techniques used to measure M_W are described and the statistical, theoretical and detector-related uncertainties are discussed in detail.

hep-ph↗
arXiv2003

Examining the Higgs boson potential at lepton and hadron colliders: a comparative analysis

We investigate inclusive Standard Model Higgs boson pair production at lepton and hadron colliders for Higgs boson masses in the range 120 GeV < m_H < 200 GeV. For m_H < 140 GeV we find that hadron colliders have a very limited capability to determine the Higgs boson self-coupling, λ, due to an overwhelming background. We also find that, in this mass range, supersymmetric Higgs boson pairs may be observable at the LHC, but a measurement of the self coupling will not be possible. For m_H > 140 GeV we examine ZHH and HH nu bar-nu production at a future e+e- linear collider with center of mass energy in the range of sqrt{s}=0.5 - 1 TeV, and find that this is likely to be equally difficult. Combining our results with those of previous literature, which has demonstrated the capability of hadron and lepton machines to determine λin either the high or the low mass regions, we establish a very strong complementarity of these machines.

hep-ph↗
arXiv2002

Determining the Higgs Boson Self Coupling at Hadron Colliders

Inclusive Standard Model Higgs boson pair production at hadron colliders has the capability to determine the Higgs boson self-coupling, lambda. We present a detailed analysis of the gg\to HH\to (W^+W^-)(W^+W^-)\to (jjl^\pmν)(jj{l'}^\pmν) and gg\to HH\to (W^+W^-)(W^+W^-)\to (jjl^\pmν)({l'}^\pmν{l''}^\mpν) (l, {l'}, {l''}=e, μ) signal channels, and the relevant background processes, for the CERN Large Hadron Collider, and a future Very Large Hadron Collider operating at a center-of-mass energy of 200 TeV. We also derive quantitative sensitivity limits for lambda. We find that it should be possible at the LHC with design luminosity to establish that the Standard Model Higgs boson has a non-zero self-coupling and that lambda / lambda_{SM} can be restricted to a range of 0-3.8 at 95% confidence level (CL) if its mass is between 150 and 200 GeV. At a 200 TeV collider with an integrated luminosity of 300 fb^{-1}, lambda can be determined with an accuracy of 8 - 25% at 95% CL in the same mass range.

hep-ph↗
arXiv2002

Electroweak Radiative Corrections to Weak Boson Production at Hadron Colliders

We summarize the status of calculations of the electroweak radiative corrections to W and Z boson production via the Drell-Yan mechanism at hadron colliders. To fully exploit the precision physics potential of the high-luminosity environment of the Fermilab Tevatron pbar p (Run II) and the CERN LHC pp colliders, it is crucial that the theoretical predictions are well under control. The envisioned precision physics program includes a precise measurement of the W boson mass and width, and the (leptonic) weak mixing angle, as well as probing the Standard Model (SM) of electroweak interactions at the highest accessible center-of-mass energies. Some numerical results are presented.

hep-ph↗
arXiv2002

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 $\MH$.

hep-ph↗
arXiv2002

Physics at Future Hadron Colliders

We discuss the physics opportunities and detector challenges at future hadron colliders. As guidelines for energies and luminosities we use the proposed luminosity and/or energy upgrade of the LHC (SLHC), and the Fermilab design of a Very Large Hadron Collider (VLHC). We illustrate the physics capabilities of future hadron colliders for a variety of new physics scenarios (supersymmetry, strong electroweak symmetry breaking, new gauge bosons, compositeness and extra dimensions). We also investigate the prospects of doing precision Higgs physics studies at such a machine, and list selected Standard Model physics rates.

hep-ph↗
arXiv2001

Theoretical and Experimental Status of the Indirect Higgs Boson Mass Determination in the Standard Model

The impact of theoretical and experimental uncertainties on the indirect determination of the Higgs boson mass, MH, in the Standard Model (SM) is discussed. Special emphasis is put on the electroweak precision observables MW (the W boson mass) and sin^2(theta_eff) (the effective leptonic mixing angle). The current uncertainties of the theoretical predictions for MW and sin^2(theta_eff) due to missing higher order corrections are conservatively estimated to delta MW \approx 7 MeV and delta sin^2(theta_eff) \approx 7 x 10^-5 . Expectations and necessary theoretical improvements for future colliders are explored. Results for the indirect MH determination are presented based on the present experimental and theoretical precisions as well as on improvements corresponding to the prospective situation at future colliders. The treatment of the different future colliders is done in a uniform way in order to allow for a direct comparison of the accuracies that can be reached. Taking all experimental, theoretical, and parametric uncertainties into account, a current upper bound on MH of \sim 200 GeV is obtained. Furthermore we find in a conservative approach that a Linear Collider with GigaZ capabilities can achieve a relative precision of about 8% (or better) in the indirect determination of MH.

hep-ph↗
arXiv2001

Status and Prospects of Theoretical Predictions for Weak Gauge Boson Production Processes at Lepton and Hadron Colliders

For the envisioned precision measurement of the W-boson mass at present and future lepton and hadron colliders it is crucial that the theoretical predictions for the underlying production processes are well under control. We briefly describe the status of the predictions for the W-pair-production processes at e+ e- colliders, e+ e- -> W+ W- -> 4f, and for W- and Z-boson production at pp and p anti-p colliders, pp, p anti-p -> W -> l nu_l and pp, p anti-p -> Z,gamma -> l+ l- (l=e,mu). We also discuss the theoretical improvements needed to meet the experimental accuracies one hopes to achieve in future experiments.

hep-ph↗
arXiv2001

Electroweak Radiative Corrections to Neutral-Current Drell-Yan Processes at Hadron Colliders

We calculate the complete electroweak O(alpha) corrections to pp, pbar p -> l+l- X (l=e, mu) in the Standard Model of electroweak interactions. They comprise weak and photonic virtual one-loop corrections as well as real photon radiation to the parton-level processes q bar q -> gamma,Z -> l+l-. We study in detail the effect of the radiative corrections on the l+l- invariant mass distribution, the cross section in the Z boson resonance region, and on the forward-backward asymmetry, A_FB, at the Fermilab Tevatron and the CERN Large Hadron Collider. The weak corrections are found to increase the Z boson cross section by about 1%, but have little effect on the forward-backward asymmetry in the Z peak region. Threshold effects of the W box diagrams lead to pronounced effects in A_FB at m(l+l-) approx 160 GeV which, however, will be difficult to observe experimentally. At high di-lepton invariant masses, the non-factorizable weak corrections are found to become large.

hep-ph↗
arXiv2001

Direct Measurement of the Top Quark Charge at Hadron Colliders

We consider photon radiation in tbar-t events at the upgraded Fermilab Tevatron and the CERN Large Hadron Collider (LHC) as a tool to measure the electric charge of the top quark. We analyze the contributions of tbar-t-gamma production and radiative top quark decays to p-p, pbar-p -> gamma l^+/- nu bbar-b jj, assuming that both b-quarks are tagged. With 20~fb^{-1} at the Tevatron, the possibility that the ``top quark'' discovered in Run I is actually an exotic charge -4/3 quark can be ruled out at the 95% confidence level. At the LHC, it will be possible to determine the charge of the top quark with an accuracy of about 10%.

hep-ph↗
arXiv2001

Theoretical Challenges for a Precision Measurement of the W Mass at Hadron Colliders

We summarize the status of calculations of the electroweak radiative corrections to W and Z boson production via the Drell-Yan mechanism at hadron colliders. To fully exploit the precision physics potential of the high-luminosity environment of the Fermilab Tevatron p \bar p (Run II) and the CERN LHC p p colliders, it is crucial that the theoretical predictions are well under control. The envisioned precision physics program includes a precise measurement of the W boson mass and the (leptonic) weak mixing angle, as well as probing the Standard Model (SM) of electroweak interactions at the highest accessible center-of-mass energies. Some numerical results are presented.

hep-ph↗
arXiv2000

Report of the Working Group on Precision Measurements

In the first part of this report, we discuss the prospects for measuring the W mass and width in Run II. The basic techniques used to measure M_W are described and the statistical, theoretical and detector-related uncertainties are discussed in detail. Alternative methods of measuring the W mass at the Tevatron and the prospects for M_W measurements at other colliders are also described. In the second part, we discuss the measurement of the forward backward asymmetry in Drell Yan production in Run II which can be used to determine the effective weak mixing angle. Estimates of the statistical and systematic uncertainties in Run II are given. The third part summarizes the features of the FORTRAN package GAPP which performs a fit to the electroweak observables and extracts the probability distribution function of the Higgs boson mass.

hep-ex↗
arXiv2000

Electroweak Radiative Corrections to W and Z Boson Production at Hadron Colliders

For the envisioned high precision measurement of the W boson mass at the Tevatron and LHC it is crucial that the theoretical predictions for the W and Z production processes are under control. We briefly summarize the status of the electroweak radiative corrections to p p(pbar) -> W -> l nu and p p(pbar) -> Z,gamma -> l+ l- (l=e,mu), and present some numerical results.

hep-ph↗
arXiv2000

Report of the Working Group on Photon and Weak Boson Production

This report discusses physics issues which can be addressed in photon and weak boson production in Run II at the Tevatron. The current understanding and the potential of Run II to expand our knowledge of direct photon production in hadronic collisions is discussed. We explore the prospects for using the W-boson cross section to measure the integrated luminosity, improving the measurement of the W and Z boson transverse momentum distributions, the Z -> b\bar b signal, and the lepton angular distribution in W decays. Finally, we consider the prospects for measuring the trilinear gauge boson couplings in Run II.

hep-ph↗
arXiv2000

Probing Neutral Gauge Boson Self-interactions in ZZ Production at Hadron Colliders

A detailed analysis of ZZ production at the upgraded Fermilab Tevatron and the CERN Large Hadron Collider is presented for general ZZZ and ZZγcouplings. Deviations from the Standard Model gauge theory structure for each of these can be parameterized in terms of two form factors which are severely restricted by unitarity at high energy. Achievable limits on these couplings are shown to be a dramatic improvement over the limits currently obtained by e^+e^- experiments.

hep-ph↗