<i>Particles, Sources and Fields</i>

Schwinger, Julian; Bernstein, Jeremy

doi:10.1063/1.3022395

Cited by 485 publications

(635 citation statements)

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“…Analogously, expansions for R pt (v) and M pt n can be written. For the first two terms, analytic expressions are available [38,39]. Here, we only give R (0) (v) and R (1) (v).…”

Section: Perturbation Theorymentioning

confidence: 99%

Bottom quark mass and αs from the ϒ system

Jamin¹,

Pich²

1997

Nuclear Physics B

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The mass of the bottom quark and the strong coupling constant α s are determined from QCD moment sum rules for the Υ system. Two analyses are performed using both the pole mass M b as well as the mass m b in the M S scheme. In the pole-mass scheme large perturbative corrections resulting from coulombic contributions have to be resummed. In the M S scheme this can be avoided by an appropriate choice for the renormalization scale. For the bottom quark mass we obtain M b = 4.60 ± 0.02 GeV and m b (m b ) = 4.13± 0.06 GeV. Our combined result from both determinations for the strong coupling is α s (M Z ) = 0.119 ± 0.008.

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“…Analogously, expansions for R pt (v) and M pt n can be written. For the first two terms, analytic expressions are available [38,39]. Here, we only give R (0) (v) and R (1) (v).…”

Section: Perturbation Theorymentioning

confidence: 99%

Bottom quark mass and αs from the ϒ system

Jamin¹,

Pich²

1997

Nuclear Physics B

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“…They made use of the two-loop vertex form factors computed by Hoang [82] and of the twoloop vacuum polarization tensor computed by Kallen and Sabry [83] and by Schwinger [84]. They employed two infrared regularization parameters: a photon mass λ and also a parameter p 0 equal to the relativistic center-of-mass three-momentum of the electron or positron in the scattering process, with λ p 0 m. This infrared regularization was convenient for their matching with the QED results, which were regulated in the same manner.…”

Section: One-photon-annihilation Contribution To the Positroniummentioning

confidence: 99%

Two-Loop Correction to the Orthopositronium Decay Rate

2002

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We give a detailed description of our calculation of the O(α 2 ) correction to the orthopositronium decay rate. The resulting correction is 45.06(26) in units of (α/π) 2 times the lowest order rate. When combined with other known corrections, the theoretical prediction for the decay rate is 7.039979(11) µs −1 , where the leading uncalculated term makes an estimated contribution of roughly 0.00002 µs −1 . Our result is in significant disagreement with two of the four highest precision measurements (at about the 5σ level), but does not contradict the others. The experimental uncertainties (≈0.002 µs −1 ) are much larger than the remaining theoretical uncertainties. We also calculate the one-photon-annihilation contribution to the positronium hyperfine structure at O(mα 6 ). This calculation is closely analogous to the decay rate calculation. Our agreement with prior results for this hyperfine structure contribution demonstrates the soundness of our approach. C 2002 Elsevier Science (USA)

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“…The first one is of course relevant for electron positron annihilation into heavy quarks at arbitrary energies, the second one for Z decays into b quarks and for top production at a future linear collider. In order α s the m 4 terms can also be obtained from the Taylor expansion of the complete answer [11,12]. This provides not only a (fairly trivial) cross check of the α s term.…”

Section: Introductionmentioning

confidence: 99%

Quartic mass corrections to Rhad

Chetyrkin

Kühn

1994

Nuclear Physics B

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The influence of nonvanishing quark masses on the total cross section in electron positron collisions and on the Z decay rate is calculated. The corrections are expanded in m 2 /s and α s . Methods similar to those applied for the quadratic mass terms allow to derive the corrections of order α s m 4 /s 2 and α 2 s m 4 /s 2 . Coefficients which depend logarithmically on m 2 /s and which cannot be absorbed in a running quark mass arise in order α 2 s . The implications of these results on electron positron annihilation cross sections at LEP and at lower energies in particular between the charm and the bottom threshold and for energies several GeV above the bb threshold are discussed.

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Particles, Sources and Fields

Cited by 485 publications

References 0 publications

Bottom quark mass and αs from the ϒ system

Bottom quark mass and αs from the ϒ system

Two-Loop Correction to the Orthopositronium Decay Rate

Quartic mass corrections to Rhad

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