Color-octet effects in radiative Υ decays

Maltoni, Fabio; Petrelli, Andrea

doi:10.1103/physrevd.59.074006

Cited by 34 publications

(63 citation statements)

References 33 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Combining this with the leading logarithm result for the color-octet contribution at the endoint [15,17], and the photon fragmentation results at low z [28,29], we can hope to obtain an accurate prediction for the photon spectrum over the full kinematic range. (i.e., they all have the same anomalous dimension).…”

Section: Discussionmentioning

confidence: 99%

“…However, since we are interested in the large z region, we will neglect them in the following. There may also be large coloroctet corrections to the rate in the endpoint region [15,17,29], which we will also neglect for the now. We also compare our result to the resummed result where the mixing has been turned off, using in place of the full resummed result in Eq.…”

Section: Resummed Ratementioning

confidence: 99%

See 1 more Smart Citation

Flavor-singlet light-cone amplitudes and radiativeΥdecays in the soft-collinear effective theory

Fleming

Leibovich

2004

Phys. Rev. D

View full text Add to dashboard Cite

We study the evolution of flavor-singlet, light-cone amplitudes in the soft-collinear effective theory (SCET), and reproduce results previously obtained by a different approach. We apply our calculation to the color-singlet contribution to the photon endpoint in radiative Υ decay. In a previous paper, we studied the color-singlet contributions to the endpoint, but neglected operator mixing, arguing that it should be a numerically small effect. Nevertheless the mixing needs to be included in a consistent calculation, and we do just that in this work. We find that the effects of mixing are indeed numerically small. This result combined with previous work on the color-octet contribution and the photon fragmentation contribution provides a consistent theoretical treatment of the photon spectrum in Υ → γX.

show abstract

Section: Discussionmentioning

confidence: 99%

Section: Resummed Ratementioning

confidence: 99%

Flavor-singlet light-cone amplitudes and radiativeΥdecays in the soft-collinear effective theory

Fleming

Leibovich

2004

Phys. Rev. D

View full text Add to dashboard Cite

show abstract

“…The spin and colour averaged squares H[QQ[n] → γg](2m Q ) of the amplitudes for the three relevant channels are (again we take only leading terms in α s ) [9]:…”

Section: Direct Contributionsmentioning

confidence: 99%

“…The photon energy spectrum in the hard subprocess QQ[n] → γX of radiative decays has been calculated in next-to-leading order perturbative QCD for both the colour singlet mode [8] and the colour octet modes [9]. Another perturbative contribution may become important in the upper endpoint region (z = 2E γ /M H → 1) of the spectrum.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Kinematic effects in radiative quarkonia decays

Wolf

2001

Phys. Rev. D

View full text Add to dashboard Cite

Non-relativistic QCD (NRQCD) predicts colour octet contributions to be significant not only in many production processes of heavy quarkonia but also in their radiative decays. We investigate the photon energy distributions in these processes in the endpoint region. There the velocity expansion of NRQCD breaks down which requires a resummation of an infinite class of colour octet operators to so-called shape functions. We model these non-perturbative functions by the emission of a soft gluon cluster in the initial state. We found that the spectrum in the endpoint region is poorly understood if the values for the colour octet matrix elements are taken as large as indicated from NRQCD scaling rules. Therefore the endpoint region should not be taken into account for a fit of the strong coupling constant at the scale of the heavy quark mass.

show abstract

The soft-energy region in the radiative decay of bound states

Ruiz-Femenía

2008

Nuclear Physics B

View full text Add to dashboard Cite

The orthopositronium decay to three photons is studied in the phase-space region where one of the photons has an energy comparable to the relative three-momentum of the e+e- system (w ~ m alpha). The NRQED computation in this regime shows that the dominant contribution arises from distances ~ 1/(mw)^(1/2), which allows to treat the Coulomb interaction perturbatively. The small-photon energy expansion of the 1-loop decay spectrum from full QED yields the same result as the effective theory. By doing the threshold expansion of the 1-loop QED amplitude we confirm that the leading term arises from a loop-momentum region where q^0 ~ q^2/m ~ w. This corresponds to a new non-relativistic loop-momentum region, which has to be taken into account for the description of a non-relativistic particle-antiparticle system that decays through soft photon emission.Comment: 28 pages, 5 figures; typos corrected, one reference added, published versio

show abstract

Color-octet effects in radiative Υ decays

Cited by 34 publications

References 33 publications

Flavor-singlet light-cone amplitudes and radiativeΥdecays in the soft-collinear effective theory

Flavor-singlet light-cone amplitudes and radiativeΥdecays in the soft-collinear effective theory

Kinematic effects in radiative quarkonia decays

The soft-energy region in the radiative decay of bound states

Contact Info

Product

Resources

About