16334731
Higgs Production by Gluon initiated Weak Boson Fusion
The gluon-gluon induced terms for Higgs production through weak-boson fusion are calculated. They form a finite and gauge-invariant subset of the NNLO corrections in the strong coupling constant. This is also the lowest order with sizeable t-channel colour exchange contributions, leading to additional hadronic activity between the outgoing jets.
120399805
Gluon Initiated Vector Boson Fusion
The gluon-gluon induced terms for Higgs production through vector-boson fusion are calculated. They are a finite and gauge-invariant subset of the NNLO corrections in the strong coupling constant. This is also the lowest order with t-channel colour exchange between the scattering quarks, leading to additional hadronic activity between the outgoing jets.
15629487
Precise predictions for the Higgs-boson decay H ---> WW/ZZ ---> 4 leptons
The decay of the standard model Higgs boson into four leptons via a virtual $W$- or $Z$-boson pair is one of the most important decay modes in the Higgs-boson search at the Large Hadron Collider. We present the complete electroweak radiative corrections of $\mathcal{O}(\ensuremath{\alpha})$ to these processes, including improvements beyond $\mathcal{O}(\ensuremath{\alpha})$ originating from heavy-Higgs effects and final-state radiation. The intermediate $W$- and $Z$-boson resonances are described (without any expansion or on-shell approximation) by consistently employing complex mass parameters for the gauge bosons (complex-mass scheme). The corrections to partial decay widths typically amount to some percent and increase with growing Higgs mass ${M}_{H}$, reaching about 8% at ${M}_{H}\ensuremath{\sim}500\text{ }\text{ }\mathrm{GeV}$. For not too large Higgs masses (${M}_{H}\ensuremath{\lesssim}400\text{ }\text{ }\mathrm{GeV}$) the corrections to the partial decay widths can be reproduced within $\ensuremath{\lesssim}2%$ by simple approximations. For angular distributions the corrections are somewhat larger and distort the shapes. For invariant-mass distributions of fermion pairs they can reach several tens of percent depending on the treatment of photon radiation. The discussed corrections have been implemented in a Monte Carlo event generator called Prophecy4f.
17284154
Precise predictions for Higgs production at e+ e- colliders and numerical calculation of one-loop integrals
Some of the most interesting Higgs-production processes at future ee colliders are of the type ee → f fH . We present a calculation of the complete O(α) corrections to these processes in the Standard Model for final-state neutrinos and top quarks. Initial-state radiation beyond O(α) at the leading-logarithmic level as well as QCD corrections are also included. The electroweak corrections turn out to be sizable and reach the order of ±10% and will thus be an important part of precise theoretical predictions for future ee colliders.
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.
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.
123036925
The low energy limit of the minimal nonlinear supersymmetric SU(5)-model; production and decay of Higgs particles
Abstract. We consider the Higgssector in the low energy limit of the minimal nonlinear supersymmetric SU(5) model. We estimate radiative corrections to the Higgs masses using the effective potential. Furthermore Higgs boson decays are investigated and differences to the MSSM are discussed.
55821746
Trilepton final state from neutralino-chargino production in mSUGRA.
The direct production of neutralino-chargino pairs in the mSUGRA scenario with decays into pure trilepton final states has a significant cross section for low neutralino masses. The trilepton signature was studied with the full and fast CMS detector simulations. The 5 signal can be observed in the dilepton invariant mass distribution at the integrated luminosity of L 30 fb for GeV.
16665734
Top Quark Production and Decay Properties at the Tevatron
The latest results from the CDF and D0 collaborations on the top-quark pair-production cross section and limits on electroweak production are presented. Included are measurements of properties of the top quark such as charge, lifetime, and the decay branching ratio t->Wb. In addition to measurements about the top quark, the selected event samples are used to study the helicity of the W boson and to search for additional exotic quarks (t') and resonances in the ttbar invariant mass spectrum.
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.
110306203
SVX4 User's manual
We present and describe the operation of the SVX4 chip. The SVX4 is a custom 128-channel analog to digital converter chip used by D0 and CDF in Run IIb to read out their respective silicon strip detectors. Each channel consists of an integrator (Front-End device, or FE) and a digitize/readout section (Back-End device, or BE). The input to each channel is sampled and temporarily stored in its own storage capacitor. Upon receiving a trigger signal, the relevant pipeline cell is reserved. Subsequent signals cause reserved cells to be digitized by a 128 parallel channel Wilkinson type 8-bit ADC, and then readout in byte-serial mode with optional zero suppression (sparsification). Salient features include (1) operation in either D0 mode or CDF mode (CDF mode features ''dead timeless operation'' or continued acquisition during digitization and readout) with an additional mixed mode of operation, (2) adjustable, loadable control parameters, including the integrator bandwidth and ADC polarity (only one input charge polarity will be used for Run IIb, but this feature remains for diagnostic purposes), (3) sparsified readout with nearest neighbor logic, (4) built-in charge injection with the ability for external voltage overriding for testing and calibration, and (5) a channel mask that ismore » used for either charge injection or for masking of channels with excessive DC current input during chip operation. This document is meant to familiarize the user with the functionality of the SVX4 and goes on to include specifications, pin outs, timings and electrical information. Additional information on the SVX4 can be found in Ref [1].« less