In the paper we recalculate and discuss high-precision theoretical predictions for cross sections of the process $e^+e^- \to Z Z$. We assume a complete one-loop implementation and a possibility of estimating the initial state polarizations, as well as the full-phase calculation. Numerical results are provided by our Monte-Carlo tools MCSANC integrator and ReneSANCe generator for typical energies and degrees of polarization of ILC and CLIC projects in two $α(0)$ and G$_μ$ electroweak schemes.
The one-loop electroweak radiative correction of the lowest order to lepton current for deep inelastic scattering of longitudinally polarized leptons by polarized nucleons is obtained in model independent way. The detailed numerical analysis within kinematical requirements of future polarization collider experiments is performed. The possibility to reduce radiative effects by detection of hard photons is studied.
For energies far above the electroweak scale, large electroweak radiative corrections occur that grow logarithmically with energy and can easily reach several tens of per cent in the TeV range. Recent work on these corrections is reviewed.
This work is devoted to a theoretical description of polarized Møller scattering. Complete one-loop electroweak radiative corrections are calculated in the helicity amplitude approach with allowance for the exact dependence on the muon mass. Numerical results are presented for integrated unpolarized and polarized cross sections as well as angular differential distributions. Calculations are performed using ReneSANCe Monte Carlo generator and MCSANC Monte Carlo integrator.
It is shown that the transition amplitudes of radiative electroweak processes like $e^-e^+ \to ν_e \olν_e \ga$, $\ga e^- \to ν_e \olν_e e^-$, and $ν_e e^- \to ν_e e^- \ga$ can be reduced and factorized into simpler forms in the Standard Model. This method can be used in reducing many calculations of complicated radiative electroweak processes in general.
We present a comparative study of radiative electroweak symmetry breaking and conventional standard model breaking, and pose the question whether experiments can distinguish one breaking mode from the other. The importance of the problem lies in the fact that the two breaking modes have very different physical interpretations concerning the mechanism of spontaneous electroweak symmetry breaking and the origin of mass.
The analysis of the newest data on the leptonic $Z$-decays and $m_W$ appears to reveal the first manifestations of electroweak radiative corrections. In fact, these data differ, at the level of $2σ$, from their electroweak Born values, while they agree, to within $1σ$, with the theoretical values which take the electroweak radiative corrections into account. Previous data were within $1σ$ in agreement with both sets of values.
The results for one-loop correction to deep inelastic scattering of longitudinal polarized leptons on longitudinal polarized hadrons are obtained withing the framework of the standard theory of electroweak interactions and ordinary quark-parton model. The on-shell renormalization scheme in t'Hooft-Feynman gauge is applied. The numerical analysis is carried out under conditions of modern particle physics experiments.Particular emphasis is laid on contributions usually ignored at RC procedure --- electroweak corrections to electromagnetic asymmetry and RC to hadronic current. The structure of RC…
The aim of this article is to review the very important role played by radiative corrections in precision electroweak physics, in the framework of both the Fermi Theory of Weak Interactions and the Standard Theory of Particle Physics. Important theoretical developments, closely connected with the study and applications of the radiative corrections, are also reviewed. The role of radiative corrections in the analysis of some important signals of new physics is also discussed.
In the QCD context, the non-singlet structure functions of u and d -quarks are identical, save the initial quark densities. Electroweak radiative corrections, being flavor-dependent, bring further difference between the non-singlets. This difference is calculated in the double-logarithmic approximation and the impact of the electroweak corrections on the non-singlet intercepts is estimated numerically.
Next-to-leading order electroweak and QCD radiative corrections to the Drell-Yan process with high dimuon masses for experiments CMS LHC at CERN have been studied in fully differential form. The FORTRAN code READY for numerical analysis of Drell-Yan observables has been presented. The radiative corrections are found to become significant for CMS LHC experiment setup.
We present some results of a new calculation of the O(alpha) electroweak radiative corrections to W boson production at hadron colliders with special emphasis on the transverse mass distribution.
We review the mechanism of radiative electroweak symmetry breaking taking place in SUSY versions of the standard model. We further discuss different proposals for the origin of SUSY-breaking and the corresponding induced SUSY-breaking soft terms. Several proposals for the understanding of the little hierarchy problem are critically discussed.
A theoretical description of elastic polarized muon-electron scattering is presented. Complete one-loop electroweak radiative corrections are calculated with taking into account the exact dependence on the muon mass. The effects due to some higher order corrections and the electroweak scheme dependence are analyzed. The case of longitudinally polarized fermions in the initial state is investigated. Analytical results are derived with the help of the SANC system. Numerical results are presented for unpolarized and polarized cross sections. Calculations are realized in the Monte Carlo integrator…
We present a next-to-leading order (NLO) computation of the full set of polarized and unpolarized electroweak semi-inclusive DIS (SIDIS) structure functions, whose knowledge is crucial for a precise extraction of polarized parton distributions. We focus on the phenomenology of the polarized structure functions for the kinematical conditions that could be reached in an Electron-Ion-Collider. We show that the NLO corrections are sizeable, particularly in the small-$x$ range. We test the sensitivity of these structure functions on certain quark distributions and compare it to the situation of inc…
The status of the present precision measurements of electroweak observables is reviewed with specific reference to the radiative parameters $S,T,U$ or equivalently $ε_1,ε_2,ε_3$. The significance of the obliqueness hypothesis is underlined and the importance of the ``local fit'' method of extracting these parameters from the data is emphasized. Possible new physics implications are briefly touched upon.
We discuss the next to the leading order (NLO) electroweak radiative corrections to the $e^- e^+ \rightarrow f^- f^+ (γ)$ cross section asymmetry, for polarized and unpolarized beam scenario. The left-right and forward-backward amplitudes, with and without radiative corrections, are evaluated and compared for various kinematics. The hard bremsstrahlung is included for arbitrary energy cuts. The radiative corrections are shown to be significant and having a non-trivial dependency on the kinematic conditions. The calculations are relevant for the ultra-precise low-energy experiment Belle~II plan…
We study Standard Model electroweak radiative corrections for fully inclusive observables with polarized fermionic beams. Our calculations are relevant in view of the possibility for Next Generation Linear colliders of having transversely and/or longitudinally polarized beams. The case of initial transverse polarization is particularly interesting because of the interplay of infrared/collinear logarithms of different origins, related both to the nonabelian SU(2) and abelian U(1) sectors. The Standard model effects turn out to be in the 10% range at the TeV scale, therefore particularly relevan…
General formulas as well as leading asymptotics for corrections to Z- and W-boson parameters are derived. Experimental data fits in Standard Model and its extensions are discussed and results are presented.
We briefly describe the RacoonWW approach to calculate radiative corrections to e+ e- -> W W -> 4 fermions and present numerical results for the total W-pair production cross section at LEP2.
Looking into the inside of radiative corrections is an interesting subject as a deeper study of the standard electroweak theory after its remarkable success in the precision analyses. I will discuss here a test of ``structure" of the EW radiative corrections to the weak-boson masses, and show that we can now analyze several different parts separately.
We present results on the full one-loop electroweak radiative corrections to the squark decay partial widths into charginos and neutralinos. We show the renormalization framework, and present numerical results for the third squark family. The corrections can reach values of ~ 10%, which are comparable to the radiative corrections from the strong sector of the model. Therefore they should be taken into account for the precise extraction of the SUSY parameters at future colliders.
Electroweak one-loop radiative corrections to the process e^+ e^- -> t tbar are revisited. Two groups from Karlsruhe and Bielefeld/Zeuthen performed independent calculations of both (virtual and soft) QED contributions and weak virtual corrections. For the angular distribution an agreement of at least eight digits for the weak corrections and of at least seven digits for additional photonic corrections is established.
We compute the next-to-leading order corrections to the cross section for the production of electroweak gauge bosons ($Z$, $W^\pm$ and $γ^*$) with large transverse momentum in double (longitudinally) polarized hadronic collisions. The calculation is fully performed in the HVBM scheme within dimensional regularization with a careful treatment of issues arising due to the appearance of $γ^5$ in polarization projectors and axial couplings. We study the phenomenological consequences of the NLO corrections at the level of both the double polarized cross section and the corresponding asymmetries at …
We present results for the complete one-loop electroweak logarithmic corrections for general processes at high energies and fixed angles. Our results are applicable to arbitrary matrix elements that are not mass-suppressed. We give explicit results for 4-fermion processes and gauge-boson-pair production in electron-positron annihilation.
We have examined the evidence for the electroweak radiative corrections in the LEP precision data along with the intriguing possibility that the QED corrections only may be sufficient to fit the data. We find that the situation is very sensitive to the precise value of $M_W$. While the world average value of $M_W$ strongly favors nonvanishing electroweak radiative corrections, the QED corrections alone can account for the data within $2σ$ in the context of the standard model. We discuss how the precision measurements of $M_W$ can provide a decisive test for the standard model with radiative co…
An alternative calculation of the lowest order electroweak radiative corrections to the single W-boson production in hadron-hadron collision in the framework of the quark parton model without any absorption of the collinear quark singularity into the parton distributions is carried out. Numerical analysis under Tevatron and LHC kinematic conditions is performed.
Theoretical predictions for Bhabha scattering observables are presented including complete one-loop electroweak radiative corrections. A longitudinal polarization of the initial beams is taken into account. Numerical results for the asymmetry $A_{LR}$ and the relative correction $δ$ are given for the set of the energy $E_{cm}=250, 500, 1000$~GeV with various polarization degrees.
We discuss the O(alpha) electroweak radiative corrections to W boson production at the Tevatron and their effect on the W boson mass extracted by experiment. The results of a new calculation of the O(alpha) corrections are presented and compared with those of a previous calculation. We also briefly discuss the O(alpha) corrections to Z boson production at the Tevatron and two-photon radiation in W and Z events.
The contributions to the electron-electron-photon vertex of two-loop electroweak corrections are calculated. The relative correction to the parity-violating asymmetry of Møller scattering for the case of 11 GeV electron scattered off the electron at rest is found to be about -0.0034 and should be taken into account at future experiment MOLLER at JLab.
The O(α) electroweak radiative corrections to the process pp, ppbar\to W \to\ell^\pmν(\ell=e,μ) are calculated. The O(α) corrections can be decomposed into separately gauge invariant contributions to the W boson production and decay processes. Factorizing the collinear singularity associated with initial state photon radiation into the parton distribution functions, we find that initial state corrections have a significantly smaller effect than final state radiative corrections. We study in detail the effect of electroweak radiative corrections on a number of interesting observables: the W tra…
The paper describes high-precision theoretical predictions obtained for the cross sections of the process $e^+e^- \to ZH$ for future electron-positron colliders. The calculations performed using the SANC platform taking into account the full contribution of one-loop electroweak radiative corrections, as well as longitudinal polarization of the initial beams. Numerical results are given for the energy range $E_{cm}=250$ GeV - $1000$ GeV with various polarization degrees.
We present a calculation of the complete electroweak O(alpha) corrections to pp/ppbar -> W+/- -> l+/- nu (l=e, mu) in the Standard Model of electroweak interactions, focusing on those corrections which do not contribute in the pole approximation. We study in detail the effect of these corrections on the transverse mass distribution, the W-width measurement, and the transverse mass ratio and cross section ratio of W and Z bosons.
We examine the possibility of necessary and inevitable radiative electroweak symmetry breaking by one-loop radiative corrections in a class of string models which are the string realization of "brane world" scenario. As an example, we consider a simple quasi-realistic model based on a D3-brane at non-supersymmetric C^3/Z_6 orbifold singularity, in which the electroweak Higgs doublet fields are identified with the massless bosonic modes of the open string on that D3-brane. We calculate the one-loop correction to the Higgs potential, and find that its vacuum expectation value can be realized in …
Complete one-loop electroweak radiative corrections to the cross section of the process $e^+e^- \to μ^-μ^+ (τ^-τ^+)$ are evaluated with the help of the \SANC system. Higher-order contributions of the initial state radiation are computed in the QED structure function formalism. Numerical results are given for the center-of-mass energy range $\sqrt{s}=5, ~7$~GeV for various polarization degrees of the initial particles.
The model of radiative neutrino mass with dark matter proposed by one of us is extended to include a real singlet scalar field. There are then two important new consequences. One is the realistic possibility of having the lightest neutral singlet fermion (instead of the lightest neutral component of the dark scalar doublet) as the dark matter of the Universe. The other is a modification of the effective Higgs potential of the Standard Model, consistent with electroweak baryogenesis.
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.
We study the scheme dependence of the two-loop expression for the $ρ$-parameter of the Standard Model in the heavy $t$-quark mass limit $m_{t} \gg m_{w}$. In the $\ms$-scheme the two-loop electroweak correction to the ${\cal O}(m_{t}^{2})$ term in $\dr$ is found greater than the QCD $\as$-correction.
At present and future hadron colliders, the precision physics program started in the past will be continued. In particular, a precise determination of the W boson mass will be carried out. This requires the calculation of the radiative corrections and their implementation in Monte Carlo event generators for data analysis. In this talk, the status of the calculation of the order alpha electroweak radiative corrections is reviewed and a study of the impact of higher order QED corrections on the W boson mass is presented.
The paper discusses the two-loop (NNLO) electroweak radiative corrections to the parity violating electron-electron scattering asymmetry induced by squaring one-loop diagrams. The calculations are relevant for the ultra-precise 11 GeV MOLLER experiment planned at Jefferson Laboratory and experiments at high-energy future electron colliders. The imaginary parts of the amplitudes are taken into consideration consistently in both the infrared-finite and divergent terms. The size of the obtained partial correction is significant, which indicates a need for a complete study of the two-loop electrow…
We study the radiative spontaneous electroweak symmetry breaking in the extra dimensions scenarios of the standard model extension proposed by Antoniadis {\it et al}, Dienes {\it et al.} and Pomarol {\it et al.}. In the framework of multi-scale effective theory when viewing from the ultraviolet cutoff scale down to the low energy scale, we find that the effects of Kaluza-Klein excitations of bosons can change the sign of the Higgs mass term of the standard model from positive to negative and therefore trigger the electroweak symmetry breaking at 1.6 (2) TeV or so when the compactification scal…
We present the full ${\cal O}(α_{ew})$ electroweak radiative corrections to the Higgs-boson production in association with $Z^0$-boson pair at an electron-positron linear collider(LC) in the standard model. We analyze the dependence of the full one-loop corrections on the Higgs-boson mass $m_{H}$ and colliding energy $\sqrt{s}$. We find that the corrections significantly suppress the Born cross section, and the ${\cal O}(α_{ew})$ electroweak radiative corrections are generally between 1.0% and -15% in our chosen parameter space, which should be taken into consideration in the future precise ex…
We perform updated and detailed calculations of the complete NLO set of electroweak radiative corrections to parity violating e- e- --> e- e- (gamma) scattering asymmetries at energies relevant for the ultra-precise Moller experiment coming soon at JLab. Our numerical results are presented for a range of experimental cuts and relative importance of various contributions is analyzed. We also provide very compact expressions analytically free from non-physical parameters and show them to be valid for fast yet accurate estimations.
Large scale calculation for the radiative corrections required for the current and future collider experiments can be done automatically using the GRACE-LOOP system. Here several results for e+e- --> 3-body processes are presented including e+e- --> e+e-H and e+e- --> nu nubar gamma.
The electroweak radiative correction, which turned out to be marginal within the standard electroweak model having the minimal Higgs sector in view of the present experimental information, fits well the experiment when the Higgs sector is extended to have two Higgs doublets. We predict the range where the charged and CP odd Higgs boson masses would lie, taking the two CP even neutral Higgs boson masses to be degenerate which makes the analysis in multiparameter space feasible. It is shown that the mass of neutral Higgs doublet boson can arbitrarily be large consistently with the $W$ mass, if t…
Electroweak radiative corrections to muon capture on nuclei are computed and found to be sizable. They enhance the capture rates for hydrogen and helium by 2.8% and 3.0% respectively. As a result, the value of the induced pseudoscalar coupling, g_P^exp, extracted from a recent hydrogen 1S singlet capture experiment is increased by about 21% to g_P^exp = 7.3 +/- 1.2 and brought into good agreement with the prediction of chiral perturbation theory, g_P^theory=8.2 +/- 0.2. Implications for helium capture rate predictions are also discussed.
The Standard Model radiative corrections to the Bhabha scattering process are considered within the one-loop approximation. Both virtual corrections and corrections for the real photon emission are taken into consideration. The calculation was performed at the energy assumed at the Belle II (Japan) facility.
The effect of virtual electroweak corrections to $e^+e^- \rightarrow t \bar{t}$ and the contribution of the radiation processes $e^+e^- \rightarrow t\bar{t}Z, t\bar{t}H$ to the inclusive top pair production cross section and forward-backward asymmetry are discussed in the high energy regime.
The contribution of the radiative tail from the quasielastic peak to low order radiative correction to deep inelastic scattering of polarized leptons by polarized $^3$He was calculated within the sum rules formalism and $y$-scaling hypothesis. Numerical analysis was carried out under the conditions of HERMES experiment.
This paper presents the high-precision theoretical predictions for $e^+e^- \to l^-l^+$ scattering. Calculations are performed using the {\tt SANC} system. They take into account complete one-loop electroweak radiative corrections as well as longitudinal polarization of initial beams. Reaction observables are obtained using the helicity amplitude method with taking into account initial and final state fermion masses. Numerical results are given for the center-of-mass energy range $\sqrt{s}=250-1000$ GeV with various degrees of polarization.
We show the computational procedure of the renormalization of the electroweak chiral Lagrangian (the 4D Higgsless standard model), and provide one simplified version of its one-loop renormalization group equations, which we demonstrate its simplicity and reliability. By analyzing the solutions of the one-loop renormalization group equations of the electroweak chiral Lagrangian, we study the parameter space of the precision test parameters at ultraviolet cutoff with the current low energy experimental constraints. We find that the region of the permitted parameter space can be greatly amplified…
We have calculated the complete electroweak O(alpha) radiative corrections to the Higgs-boson production process e+ e- -> t anti-t H 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. Both the photonic and the genuine weak corrections reach the order of about 10% or even more and show a non-trivial dependence on the Higgs-boson mass and on the scattering energy. We compare our results with two previous …
In calculating electroweak radiative corrections at two-loop level, one encounters Feynman graphs with several different masses on the internal propagators and on the external legs, which lead to complicated scalar functions. We describe a general analytic-numerical reduction scheme for evaluating any two-loop diagrams with general kinematics and general renormalizable interactions, whereby ten basic functions form a complete set after tensor reduction. We illustrate this scheme by applying it to two- and three-point functions. We discuss the treatment of infrared singularities within this num…
We evaluate dominant two-loop corrections to the triple Higgs coupling and strength of a first-order electroweak phase transition in the inert Higgs doublet model. It is found that sunset diagrams can predominantly enhance the former and reduce the latter. As a result, the triple Higgs coupling normalized by the standard model value at two-loop level is more enhanced than the corresponding one-loop value.
Enhanced radiative corrections generated in SUSY extensions of the Standard Model make the fit of the precision data ($Z$-boson decay parameters and $W$-boson mass) worse. This negative effect is washed out for heavy enough squarks due to decoupling property of SUSY models. We find that even for light squarks the enhanced radiative corrections can be small. In this case substantial $\tilde{t}_L \tilde{t}_R$ mixing is necessary.
The paper discusses the two-loop (NNLO) electroweak radiative corrections to the parity-violating Moller scattering asymmetry induced by insertions to boxes of electron and neutrino mass operators (fermion self-energies), vertex functions and boson self-energies. The results will be relevant to the ultra-precise 11 GeV MOLLER experiment planned at the Jefferson Laboratory, which will measure the weak charge of the electron and search for new physics. The numerical estimations for the NNLO contribution to the cross section asymmetry are presented.
Recent anomalies in cosmic rays data, namely from the PAMELA collaboration, can be interpreted in terms of TeV scale decaying/annihilating Dark Matter. We analyze the impact of radiative corrections coming from the electroweak sector of the Standard Model on the spectrum of the final products at the interaction point. As an example, we consider virtual one loop corrections and real gauge bosons emission in the case of a very heavy vector boson annihilating into fermions. We show that the effect of electroweak corrections is relevant, but not as big as sometimes claimed in the literature. At su…
