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Fadin, V.S.; Khoze, V. A.; Martin, A. D.; Chapovsky, A.P.

doi:10.1103/physrevd.52.1377

Cited by 53 publications

(92 citation statements)

References 14 publications

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“…Two-photon exchange is only a few-permille correction, confirming the expectation that Coulomb exchanges do not have to be summed to all orders due to the large width of the W boson. The one and two Coulomb-exchange terms have already been discussed in [10,11].…”

Section: Coulomb Correctionsmentioning

confidence: 99%

“…The contributions in this class arise from evaluating the first term in (4) at one loop, see Figure 2, but with one insertion of the subleading bilinear terms in the Lagrangian (11), which correspond to kinetic energy and width corrections, or with production operator products…”

Section: Calculations In the Effective Theorymentioning

confidence: 99%

“…The exchange of potential photons with energy k 0 ∼ M W δ and three-momentum k ∼ M W √ δ, shown in Figure 9, corresponds to insertions of the non-local four-boson interactions in the effective Lagrangian (11). These insertions can be summed to all orders in terms of the Green function G c ( r, r ′ ; E) of the Schrödinger operator − ∇ 2 /M W − α/r evaluated at r = r ′ = 0.…”

Section: Coulomb Correctionsmentioning

confidence: 99%

“…The relevant Feynman rules are given by the coupling of the soft photon to the Ω ± fields in the PNRQED Lagrangian (11) and to the collinear electrons and positrons contained in the SCET Lagrangian. The latter is simply the eikonal coupling ±ien µ , where n µ is the direction of the four-momentum of the electron or positron.…”

Section: Soft-photon Correctionsmentioning

confidence: 99%

“…This approximation was supposed to break down for kinematic reasons in the threshold region. Thus, when this project was begun [9], there existed only LO calculations in the threshold region as well as studies of the effect of Coulomb photon exchanges [10,11], rendering the effective field theory approach [12][13][14] the method of choice for the NLO calculation. Meanwhile a full NLO calculation of four-fermion production has been performed in the complex mass scheme [15,16] without any kinematic approximations, and for the fully differential cross sections in the continuum or near threshold.…”

Section: Introductionmentioning

confidence: 99%

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Four-fermion production near the W pair-production threshold

et al. 2008

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We perform a dedicated study of the four-fermion production process e − e + → µ −ν µ ud X near the W pair-production threshold in view of the importance of this process for a precise measurement of the W boson mass. Accurate theoretical predictions for this process require a systematic treatment of finite-width effects. We use unstable-particle effective field theory (EFT) to perform an expansion in the coupling constants, Γ W /M W , and the non-relativistic velocity v of the W boson up to next-to-leading order in Γ W /M W ∼ α ew ∼ v 2 . We find that the dominant theoretical uncertainty in M W is currently due to an incomplete treatment of initial-state radiation. The remaining uncertainty of the NLO EFT calculation translates into δM W ≈ 10 -15 MeV, and to about 5 MeV with additional input from the NLO four-fermion calculation in the full theory.

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Section: Coulomb Correctionsmentioning

confidence: 99%

Section: Calculations In the Effective Theorymentioning

confidence: 99%

Section: Coulomb Correctionsmentioning

confidence: 99%

Section: Soft-photon Correctionsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Four-fermion production near the W pair-production threshold

et al. 2008

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New Directions in Quantum Chromodynamics

Brodsky

2000

Particle Production Spanning MeV and TeV Energies

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I review the light-cone Fock state represention and its associated light-cone fac-torization scheme as a method for encoding the flavor, momentum, and helicity properties of hadrons in the form of universal process-independent and frame-independent amplitudes. Discrete light-cone quantization (DLCQ) provides a matrix representation of the QCD Hamiltonian and a nonperturbative method for computing the quark and gluon bound state wavefunctions. A number of applications of the light-cone formalism are discussed, including an exact light-cone Fock state representation of semi-leptonic B decay amplitudes. Hard exclusive and diffractive reactions are shown to be sensitive to hadron distribution amplitudes, the valence Fock state hadronic wavefuc-tions at small impact separation. Semi-exclusive reactions are shown to provide new flavor-dependent probes of distribution amplituds and new types of deep inelastic currents. "Self-resolving" diffractive processes and Coulomb dissociation are discussed as a direct measure of the light-cone wavefunctions of hadrons. Alternatively, one can use Coulomb dissociation to resolve nuclei in terms of their nucleonic and mesonic degrees of freedom. I also discuss several theoretical tools which eliminate theoretical ambiguities in perturbative QCD predictions. For example, commensurate scale relations are perturbative QCD predictions based on conformal symmetry which relate observable to observable at fixed relative scale; such relations have no renormaliza-tion scale or scheme ambiguity. I also discuss the utility of the α V coupling, defined from the QCD heavy quark potential, as a useful physical expansion parameter for perturbative QCD and grand unification. New results on the analytic fermion masses dependence of the α V coupling at two-loop order are presented.

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Final state Sommerfeld effect on dark matter relic abundance

Cui

Luo

2021

J. High Energ. Phys.

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If the annihilation products of dark matter (DM) are non-relativistic and if there is some long-range force between them, there can be Sommerfeld effect for the final state particles. We study this effect on DM relic abundance in the thermal freeze-out scenario. As a proof of concept, we consider the case of a DM pair annihilation into a final state pair, assuming that the mutual interactions between the two final state particles give rise to a Coulomb-like potential, and that the masses of the initial and final state particles are similar, so that both the initial and final state particles are non-relativistic. The size of the final state Sommerfeld (FSS) effect depends on the strength of the potential, as well as on the mass ratio of the final and initial state particles. We find that the impact of the FSS effect on DM relic abundance can be significant, and an electroweak sized long-range interaction is large enough to make a correction well beyond the observational accuracy. Another feature of the FSS effect is that it could be suppressed when its time scale is longer than the lifetime of the final state particles. As a corollary, we also study in the DM coannihilation scenario where the initial state Sommerfeld effect between two coannihilators could be reduced due to their instability, which may need to be taken into account for an accurate calculation of the DM relic abundance.

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Coulomb effects inW+W−production

Cited by 53 publications

References 14 publications

Four-fermion production near the W pair-production threshold

Four-fermion production near the W pair-production threshold

New Directions in Quantum Chromodynamics

Final state Sommerfeld effect on dark matter relic abundance

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