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Register a new userElectroweak corrections to $pp to mu^+mu^-e^+e^- + X$ at the LHC -- a Higgs background study
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The first complete calculation of the next-to-leading-order electroweak corrections to four-lepton production at the LHC is presented, where all off-shell effects of intermediate Z bosons and photons are taken into account. Focusing on the mixed final state $mu^+mu^-e^+e^-$, we study differential cross sections that are particularly interesting for Higgs-boson analyses. The electroweak corrections are divided into photonic and purely weak corrections. The former exhibit patterns familiar from similar W/Z-boson production processes with very large radiative tails near resonances and kinematical shoulders. The weak corrections are of the generic size of 5% and show interesting variations, in particular a sign change between the regions of resonant Z-pair production and the Higgs signal.
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This paper presents a full simulation study of the measurement of the production cross section ($sigma_{mathrm{ZH}}$) of the Higgsstrahlung process $mathrm{e^{+}e^{-}rightarrow ZH}$ and the Higgs boson mass ($M_{mathrm{H}}$) at the International Linear Collider (ILC), using events in which a Higgs boson recoils against a Z boson decaying into a pair of muons or electrons. The analysis is carried out for three center-of-mass energies $sqrt{s}$ = 250, 350, and 500 GeV, and two beam polarizations $mathrm{e_{L}^{-}e_{R}^{+}}$ and $mathrm{e_{R}^{-}e_{L}^{+}}$, for which the polarizations of $mathrm{e^{-}}$ and $mathrm{e^{+}}$ are $left(Pmathrm{e^{-}},Pmathrm{e^{+}}right)$ =($-$80%, +30%) and (+80%, $-$30%), respectively. Assuming an integrated luminosity of 250 $mathrm{fb^{-1}}$ for each beam polarization at $sqrt{s}$ = 250 GeV, where the best lepton momentum resolution is obtainable, $sigma_{mathrm{ZH}}$ and $M_{mathrm{H}}$ can be determined with a precision of 2.5% and 37 MeV for $mathrm{e_{L}^{-}e_{R}^{+}}$ and 2.9% and 41 MeV for $mathrm{e_{R}^{-}e_{L}^{+}}$, respectively. Regarding a 20 year ILC physics program, the expected precisions for the $mathrm{HZZ}$ coupling and $M_{mathrm{H}}$ are estimated to be 0.4% and 14 MeV, respectively. The event selection is designed to optimize the precisions of $sigma_{mathrm{ZH}}$ and $M_{mathrm{H}}$ while minimizing the bias on the measured $sigma_{mathrm{ZH}}$ due to discrepancy in signal efficiencies among Higgs decay modes. For the first time, model independence has been demonstrated to a sub-percent level for the $sigma_{mathrm{ZH}}$ measurement at each of the three center-of-mass energies. The results presented show the impact of center-of-mass energy and beam polarization on the evaluated precisons and serve as a benchmark for the planning of the ILC run scenario.
We study muon pair production $ e^+ e^- to mu^+ mu^-$ in the noncommutative(NC) extension of the standard model using the Seiberg-Witten maps of this to the second order of the noncommutative parameter $Theta_{mu u}$. Using $mathcal{O}(Theta^2)$ Feynman rules, we find the $mathcal{O}(Theta^4)$ cross section(with all other lower order contributions simply cancelled) for the pair production. The momentum dependent $mathcal{O}(Theta^2)$ NC interaction significantly modifies the cross section and angular distributions which are different from the commuting standard model. We study the collider signatures of the space-time noncommutativity at the International Linear Collider(ILC) and find that the process $ e^+ e^- to mu^+ mu^-$ can probe the NC scale $Lambda$ in the range $0.8 - 1.0$ TeV for typical ILC energy ranges.
In this present paper, we investigate the muon pairs production in the interaction between two quasireal photons in $e^+e^-$ collision. The total and differential cross section of the process $gamma gamma to mu^+mu^-$ at a beam energy of photons from 3 GeV to 40 GeV in the center-of-mass and for different values of muon transverse momentum and the muon rapidity and the muon angle are calculated. We also study the total cross section, as a function of the $e^+ e^-$ center-of-mass energy $sqrt {s}$ in the region 5 GeV $leq sqrt {s} leq$ 209 GeV process of the $e^+ +e^- to e^+ + e^- +mu^+ + mu^-$ by the two-photon mechanism. The obtained our results are in satisfactory agreement with the experimental data.
The calculation of the full electroweak O(alpha) corrections to the charged-current four-fermion production processes e+e- --> nu_tau tau+ mu- anti-nu_mu, u anti-d mu- anti-nu_mu, and u anti-d s anti-c is briefly reviewed. The calculation is performed using the complex-mass scheme for the gauge-boson resonances. The evaluation of the occurring one-loop tensor integrals, which include 5- and 6-point functions, requires new techniques. The effects of the complete O(alpha) corrections to the total cross section and to the production-angle distribution are discussed and compared to predictions based on the double-pole approximation, revealing that the latter approximation is not sufficient to fully exploit the potential of a future linear collider in an analysis of W-boson pairs at high energies.
We have calculated the complete electroweak O(alpha) radiative corrections to the single Higgs-boson production processes e+ e- --> nu_l anti-nu_l H (l=e,mu,tau) in the electroweak Standard Model. Initial-state radiation beyond O(alpha) 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_mu 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 per cent. The confusing situation in the literature regarding differing results for the fermionic corrections to this process is clarified.
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