scholarly journals Correcting the Colour-Dipole Cascade Model with Fixed Order Matrix Elements

2002 ◽  
Vol 2002 (05) ◽  
pp. 046-046 ◽  
Author(s):  
Leif Lönnblad
Keyword(s):  
Cascade Model ◽  
Matrix Elements ◽  
Order Matrix ◽  
Fixed Order ◽  
Colour Dipole

scholarly journals Toward massless and massive event shapes in the large-β0 limit

2021 ◽  
Vol 2021 (7) ◽  
Author(s):  
N. G. Gracia ◽  
V. Mateu
Keyword(s):  
Top Quark ◽  
Matrix Elements ◽  
Position Space ◽  
Positive Real ◽  
Full Agreement ◽  
Anomalous Dimensions ◽  
Fixed Order ◽  
Principal Value ◽  
Contour Deformation ◽  
Perturbative Corrections

Abstract We present results for SCET and bHQET matching coefficients and jet functions in the large-β0 limit. Our computations exactly predict all terms of the form $$ {\alpha}_s^{n+1}{n}_f^n $$ α s n + 1 n f n for any n ≥ 0, and we find full agreement with the coefficients computed in the full theory up to $$ \mathcal{O}\left({\alpha}_s^4\right) $$ O α s 4 . We obtain all-order closed expressions for the cusp and non-cusp anomalous dimensions (which turn out to be unambiguous) as well as matrix elements (with ambiguities) in this limit, which can be easily expanded to arbitrarily high powers of αs using recursive algorithms to obtain the corresponding fixed-order coefficients. Examining the poles laying on the positive real axis of the Borel-transform variable u we quantify the perturbative convergence of a series and estimate the size of non-perturbative corrections. We find a so far unknown u = 1/2 renormalon in the bHQET hard factor Hm that affects the normalization of the peak differential cross section for boosted top quark pair production. For ambiguous series the so-called Borel sum is defined with the principal value prescription. Furthermore, one can assign an ambiguity based on the arbitrariness of avoiding the poles by contour deformation into the positive or negative imaginary half-plane. Finally, we compute the relation between the pole mass and four low-scale short distance masses in the large-β0 approximation (MSR, RS and two versions of the jet mass), work out their μ- and R-evolution in this limit, and study how their implementation improves the convergence of the position-space bHQET jet function, whose three-loop coefficient in full QCD is numerically estimated.

scholarly journals QCD event generators with next-to-leading order matrix-elements and parton showers

2003 ◽  
Vol 654 (1-2) ◽  
pp. 301-319 ◽  
Author(s):  
Y. Kurihara ◽  
J. Fujimoto ◽  
T. Ishikawa ◽  
K. Kato ◽  
S. Kawabata ◽  
...  
Keyword(s):  
Matrix Elements ◽  
Leading Order ◽  
Order Matrix

NLO K factors for ZZ double vector boson pairs in proton–proton collisions

2018 ◽  
Vol 33 (26) ◽  
pp. 1850153
Author(s):  
Kamuran Dilsiz
Keyword(s):  
Z Boson ◽  
Vector Boson ◽  
Higher Order ◽  
Boson Mass ◽  
Matrix Elements ◽  
Proton Proton ◽  
Proton Collisions ◽  
Order Matrix ◽  
The Impact ◽  
Proton Proton Collisions

The impact of higher-order matrix elements and [Formula: see text] and [Formula: see text] scales on the NLO K factors for ZZ vector boson pairs in proton–proton collisions are presented in this study. All predictions are performed using MCFM-8.0 Monte Carlo generator. First, the QCD predictions of ZZ production at LO and NLO accuracies are obtained using two most recent PDFs, MMHT2014 and CT14. To discuss the impact of higher-order matrix elements on the NLO K factors, both LO and NLO corrections are obtained by LO, NLO and NNLO matrix elements of these two most recent PDFs. Then, the impact of [Formula: see text] and [Formula: see text] scales on the NLO K factors are further discussed by using six different values of [Formula: see text] and [Formula: see text] in a range of [Formula: see text], [Formula: see text], where [Formula: see text] is Z boson mass.

Calculation of recoil-order matrix elements for the beta decays ofF20andNa20.

1977 ◽  
Vol 15 (6) ◽  
pp. 2178-2186 ◽  
Author(s):  
Frank P. Calaprice ◽  
W. Chung ◽  
B. H. Wildenthal
Keyword(s):  
Matrix Elements ◽  
Order Matrix ◽  
Beta Decays
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