[Paper Review] Electroweak corrections to the Drell-Yan process in the high dimuon mass range

V. Zykunov|ArXiv.org|Feb 20, 2007

Particle physics theoretical and experimental studies3 citations

TL;DR

This paper presents a complete set of one-loop electroweak radiative corrections at O(α) for the Drell-Yan process at high dimuon masses (up to 5 TeV), using the Asymptotic Approach and generalized functions (θ and δ-functions) to enable fast, accurate numerical computation. The FORTRAN code READY computes corrections that reach −5.6% at 1 TeV and −35.3% at 5 TeV, with dominant negative contributions from W-boson boxes and final-state radiation, crucial for precision New Physics searches at the LHC.

ABSTRACT

The complete electroweak radiative O(α) corrections to the Drell-Yan process at large invariant dimuon mass have been studied. All formulas for the cross sections and kinematical restrictions are presented in explicit form, for the simplification of calculation and coding the theta- and delta-functions are actively used. The FORTRAN code READY for the numerical analysis in the high energy region corresponding to the future experiments at the CERN Large Hadron Collider has been constructed. To simulate the detector acceptance we used the standard CMS detector cuts. The radiative corrections are found to become large at high dimuon mass M, the complete corrections at "bare" setup change the dimuon mass distribution up to ~ -5.6% (-23.2%; -35.3%) at the LHC energy and M=1 (3; 5)TeV.

Motivation & Objective

• To compute precise electroweak radiative corrections at O(α) for the Drell-Yan process in the high invariant dimuon mass regime (1–5 TeV), relevant for LHC New Physics searches.
• To develop a fast and accurate numerical tool (READY code) for inclusion in Monte Carlo generators by expressing cross sections and kinematical constraints in explicit, integrable form using θ- and δ-functions.
• To quantify the impact of individual electroweak correction contributions—such as boson self-energies, vertex corrections, boxes, and bremsstrahlung—on the dimuon mass distribution at high energies.
• To simulate detector effects using standard CMS cuts (pT ≥ 20 GeV, |η| ≤ 2.4) and assess corrections under "bare" muon identification conditions (no smearing, no recombination).
• To validate results against existing programs (SANC, ZGRAD, DY2002) and ensure reliability for future high-precision analyses.

Proposed method

• The Asymptotic Approach (AA) is applied to systematically expand electroweak corrections in powers of logarithms, especially Double Sudakov Logarithms (DSL), at high energy scales.
• Cross sections and kinematical constraints are expressed in terms of generalized functions (θ and δ-functions), enabling efficient adaptive multidimensional integration for numerical evaluation.
• The FORTRAN code READY is implemented to compute the full O(α) electroweak corrections, including virtual corrections (BSE, HV, boxes), initial- and final-state radiation (ISR, FSR), and interference terms.
• The calculation includes all relevant contributions: boson self-energies (BSE), heavy quark vertex corrections (HV), γγ, γZ, ZZ, WW boxes, and soft/hard photon emission (ISR, FSR, INT).
• Detector effects are modeled via standard CMS acceptance cuts: pT(μ) ≥ 20 GeV, |η(μ)| ≤ 2.4, and a "bare" setup with no muon energy smearing or photon recombination.
• The numerical analysis is performed at LHC energy (13–14 TeV), focusing on the dimuon mass distribution and relative corrections δM^C as a function of M.

Experimental results

Research questions

• RQ1 How large are the complete O(α) electroweak corrections to the Drell-Yan process at high dimuon masses (1–5 TeV) in the context of LHC physics?
• RQ2 Which individual electroweak contributions (e.g., W-boxes, vertex corrections, bremsstrahlung) dominate the radiative corrections in the high-mass regime?
• RQ3 To what extent do Double Sudakov Logarithms (DSL) and Single Sudakov Logs (SSL) influence the correction pattern at TeV-scale energies?
• RQ4 How do the corrections depend on detector-level cuts, and what is the impact of using a "bare" muon identification setup?
• RQ5 How do the results compare with existing programs (SANC, ZGRAD, DY2002), and what is the significance of cross-checking for future precision analyses?

Key findings

• The complete electroweak corrections at O(α) reduce the dimuon mass distribution by up to −5.6% at M = 1 TeV and −35.3% at M = 5 TeV under the "bare" setup at LHC energy.
• The dominant negative contribution comes from W-boson boxes, which interfere destructively with the Born amplitude and scale with Sudakov logarithms.
• Final-state radiation (FSR) contributes −0.071, and ISR contributes −0.019, both significantly reducing the cross section.
• The WW-box contribution is uniquely negative and larger in magnitude than the positive contributions from vertex corrections (HV) and boson self-energies (BSE), which are ~+0.07 and ~+0.12, respectively.
• Single Sudakov Logs (SSL) in vertex diagrams (Fig.1,d–e) play a crucial role, being up to 9 times larger than Double Sudakov Logs (DSL) at M = 1 TeV, despite the latter being formally dominant in the asymptotic expansion.
• The total correction is negative and reaches −0.056 (−5.6%) at M = 1 TeV, indicating a substantial electroweak background that must be accounted for in New Physics searches.