119389130
Electroweak corrections to e+ e- -> nu anti-nu H and e+ e- -> t anti-t H
The most interesting Higgs-production processes at future e+ e- colliders belong to the process class e+ e- ->f anti-f H. We study the full O(alpha) corrections to this reaction in the Standard Model for neutrinos and top quarks in the final state. Leading higher-order corrections from initial-state radiation and QCD corrections are also taken into account. Although cancellations between the different kinds of corrections occur, the full corrections are of the order of +/-10% and thus important ingredients in the theoretical predictions for future e+ e- colliders.
15696182
Precision calculations for H -> WW/ZZ -> 4fermions with PROPHECY4f
PROPHECY4f is a Monte Carlo event generator for precise simulations of the Higgs-boson decay H -> WW/ZZ -> 4fermions, supporting leptonic, semileptonic, and four-quark final states. Both electroweak and QCD corrections are included. Treating the intermediate gauge bosons as resonances, the calculation covers the full Higgs-boson mass range above, near, and below the gauge-boson pair thresholds. In this article we pay particular attention to the recently implemented option of PROPHECY4f to generate unweighted events.
53579185
Higgs production and decay with a fourth Standard-Model-like fermion generation
State-of-the-art predictions for the Higgs-boson production cross section via gluon fusion and for all relevant Higgs-boson decay channels are presented in the presence of a fourth Standard-Model-like fermion generation. The qualitative features of the most important differences to the genuine Standard Model are pointed out, and the use of the available tools for the predictions is described. For a generic mass scale of 400−600 GeV in the fourth generation explicit numerical results for the cross section and decay widths are presented, revealing extremely large electroweak radiative corrections, e.g., to the cross section and the Higgs decay into WW or ZZ pairs, where they amount to about −50 % or more. This signals the onset of a non-perturbative regime due to the large Yukawa couplings in the fourth generation. An estimate of the respective large theoretical uncertainties is presented as well.
10525627
Electroweak radiative corrections to single Higgs-boson production in e+e− annihilation
Abstract We have calculated the complete electroweak O (α) radiative corrections to the single Higgs-boson production processes e + e − →ν l ν l H ( l =e, μ , τ ) in the electroweak Standard Model. Initial-state radiation beyond O (α) is included in the structure-function approach. The calculation of the corrections is briefly described, and numerical results are presented for the total cross-section. In the G μ scheme, the bulk of the corrections is due to initial-state radiation, which affects the cross-section at the level of −7% at high energies and even more in the ZH threshold region. The remaining bosonic and fermionic corrections are at the level of a few percent. The confusing situation in the literature regarding differing results for the fermionic corrections to this process is clarified.
8016343
Testing coupling relations in SUSY QCD at a linear collider
Supersymmetry predicts that gauge couplings are equal to the corresponding gaugino-sfermion-fermion Yukawa couplings. This prediction can be tested for the QCD sector of the MSSM by studying the processes eplus+eminus -> squark+antisquark+gluon and eplus+eminus -> squark+antiquark+gluino at a future linear collider. We present results for these processes at next-to-leading order in alpha_s in the framework of the MSSM. We find sizable SUSY-QCD corrections. The renormalization scale dependence is significantly reduced at next-to-leading order.
117974501
Radiative corrections to W gamma gamma production at the LHC
Radiative W production at hadron colliders is an important testing ground for the Standard Model. We consider W gamma gamma production which is sensitive to the quartic WW gamma gamma coupling. Furthermore the Standard Model amplitude for this process contains a radiation zero. We present a calculation of the NLO QCD corrections for W gamma gamma production at the LHC.
120302616
Inclusive e+e- pair production in cold nuclear matter
119214048
Net-charge fluctuations and balance functions at the LHC
Abstract The measurement of event–by–event fluctuations and charge–dependent particle correlations are used to study properties of nuclear matter at high temperatures as produced in ultrarelativistic heavy–ion collisions. We present results for event–by–event net–charge fluctuations and charge balance functions in Δη and Δφ in Pb–Pb collisions at s NN = 2.76 TeV .
119399268
Measurement of Boson Self Couplings at LEP and Search for Anomalies
With center of mass energies up to 209 GeV of LEP II, massive W and Z bosons can be produced in pairs and jointly with photons. This allows to study boson-boson couplings. Since the W and Z bosons are unstable and decay into fermions, two- and four-fermion final states, accompanied possibly by photons, play an important role for these measurements. The couplings of the W to other bosons have been measured to be g1Z = 0.990+0.023-0.024, kappa_gamma = 0.896+0.058-0.056, and lambda_gamma = -0.023 +0.025 -0.023. They are in agreement with the Standard Model expectation of g1Z = 1, kappa_gamma = 1, and lambda_gamma = 0. No sign for couplings of three neutral bosons, parametrized by the couplings f_i^V and h_i^V, and for anomalous couplings of four gauge bosons, parametrized by a_0, a_n and a_c has been found.
109952852
Power supply and pulsing strategies for the future linear colliders
The concept of the power delivery systems of the future linear colliders exploits the pulsed bunch structure of the beam in order to minimize the average current in the cables and the electronics and thus to reduce the material budget and heat dissipation. Although modern integrated circuit technologies are already available to design a low-power system, the concepts on how to pulse the front-end electronics and further reduce the power are not yet well understood. We propose a possible implementation of a power pulsing system based on a DC/DC converter and we choose the Analog Hadron Calorimeter as a specific example. The model features large switching currents of electronic modules in short time intervals to stimulate the inductive components along the cables and interconnections.
116194687
Scintillator materials for calorimetry
Requirements for fast, dense scintillator materials for calorimetry in high energy physics and approaches to satisfying these requirements are reviewed with respect to possible hosts and luminescent species. Special attention is given to cerium-activated crystals, core-valence luminescence, and glass scintillators. The present state of the art, limitations, and suggestions for possible new scintillator materials are presented.