Subleading power factorization with radiative functions

Moult, Ian; Stewart, Iain W.; Vita, Gherardo

doi:10.1007/jhep11(2019)153

Cited by 79 publications

(96 citation statements)

References 226 publications

(487 reference statements)

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“…This is due to the fact that the LP NLL resummed result is heavily scale dependent, and this dependence is greatly reduced by the inclusion of soft quark emission. This shows that soft quark emission is relevant at next-to-leading power [61,78] and deserves further attention.…”

Section: Discussionmentioning

confidence: 82%

“…By including the off-diagonal components of the splitting functions, one allows for the emission of (soft) quarks. This changes the identity of the emitter and is not in the spirit of soft gluon resummation, but it does give rise to NLP contributions [61,78]. Finally, also for the singlet case we have the option to evolve with the full splitting matrices.…”

Section: Differences Between Methods At the Next-to-leading Power Levelmentioning

confidence: 99%

“…With option 2b (and 2c) we also allow for the emission of collinear quarks. This results in an NLP LL contribution when the quark momentum becomes soft-collinear [61,78]. As the full NLO beta function (i.e.…”

Section: Differences Between Methods At the Next-to-leading Power Levelmentioning

confidence: 99%

“…A first principles NLP factorization analysis in the context of Yukawa theory was undertaken in [45][46][47]. Related analyses have been carried out in the SCET framework [48][49][50][51][52][53][54][55][56][57][58][59][60][61] and results using either diagrammatic or effective theory methods have been shown to be potentially useful for improving the accuracy of fixed-order calculations [62][63][64][65][66].…”

Section: Introductionmentioning

confidence: 99%

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Next-to-leading power threshold effects for resummed prompt photon production

et al. 2019

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We assess and compare different methods for including leading threshold logarithms at nextto-leading-power in prompt photon production at hadron colliders, for both the direct and parton fragmentation mechanisms. We do this in addition to next-to-leading logarithmic threshold and joint resummation at leading power. We study the size of these effects and their scale variations for LHC kinematics. We find that the next-to-leading power effects have a noticeable effect on the photon transverse momentum distribution, typically of order O(10%), depending on the method of inclusion. Our results indicate that next-to-leading power terms can reduce the scale dependence of the distribution considerably. † Deceased. We dedicate this paper to his memory. arXiv:1905.11771v1 [hep-ph] 28 May 2019 Recently, the SCET framework has been used to demonstrate that the leading-logarithmic (LL) NLP contributions to Drell-Yan production can indeed be resummed [59]. Preliminary studies [67][68][69] were performed for the resummation of a large class of leading logarithmic (LL with m = 2n − 1) NLP terms for direct production of prompt photons, in both threshold and joint resummation. In this paper we extend this work in a number of new directions. First, we now include the fragmentation mechanism, which requires additional colour structures in the hard scattering. Second, we assess different approaches to include initial and final state NLP terms and analyze them for both threshold and joint resummation. We furthermore examine the effect of including the NLP terms on the scale dependence of the resummed cross-section. Finally, we use the prompt photon process as a case study of NLP effects for a final state containing color-charged particles, providing numerical studies to assess the size of the NLP terms. The paper is organized as follows. In section 2 we review the threshold and joint resummed photon p T distribution, and discuss the inclusion of NLP effects for the initial and final state. In section 3 we assess the numerical impact of these corrections, and we conclude in section 4. In appendix A we collect explicit expressions for quantities listed in section 2, while in appendix B we compare the NLO expansion of our resummed expressions at NLP with exact results.

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Section: Discussionmentioning

confidence: 82%

Section: Differences Between Methods At the Next-to-leading Power Levelmentioning

confidence: 99%

Section: Differences Between Methods At the Next-to-leading Power Levelmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Next-to-leading power threshold effects for resummed prompt photon production

et al. 2019

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“…In the final stages of preparing this paper, Ref. [65] appeared, which addresses the emission of soft and collinear radiation (including quarks) up to next-to-leading power, within the framework of soft collinear effective theory.…”

Section: Note Addedmentioning

confidence: 99%

Next-to-leading power threshold effects for inclusive and exclusive processes with final state jets

Beekveld

Beenakker

Laenen

et al. 2020

J. High Energ. Phys.

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It is well known that cross-sections in perturbative QCD receive large corrections from soft and collinear radiation, whose properties must be resummed to all orders in the coupling. Whether or not the universal properties of this radiation can be extended to next-to-leading power (NLP) in the threshold expansion has been the subject of much recent study. In this paper, we consider two types of NLP effects: the interplay of next-to-soft and collinear radiation in processes with final state jets and the NLP contributions stemming from soft quarks. We derive an NLP amplitude for soft gluons and quarks, valid for an arbitrary number of coloured or colourless massless final state particles. We show explicitly that this framework can be used to correctly obtain the dominant NLP effects in three different types of processes at next-to-leading order: deep-inelastic scattering, hadroproduction via electron-positron annihilation and prompt photon production. Our results provide an important ingredient for developing a universal resummation formalism for NLP effects.

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Factorization at subleading power and endpoint divergences in h → γγ decay. Part II. Renormalization and scale evolution

Liu

Mecaj

Neubert

et al. 2021

J. High Energ. Phys.

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Building on the recent derivation of a bare factorization theorem for the b-quark induced contribution to the h → γγ decay amplitude based on soft-collinear effective theory, we derive the first renormalized factorization theorem for a process described at subleading power in scale ratios, where λ = mb/Mh « 1 in our case. We prove two refactorization conditions for a matching coefficient and an operator matrix element in the endpoint region, where they exhibit singularities giving rise to divergent convolution integrals. The refactorization conditions ensure that the dependence of the decay amplitude on the rapidity regulator, which regularizes the endpoint singularities, cancels out to all orders of perturbation theory. We establish the renormalized form of the factorization formula, proving that extra contributions arising from the fact that “endpoint regularization” does not commute with renormalization can be absorbed, to all orders, by a redefinition of one of the matching coefficients. We derive the renormalization-group evolution equation satisfied by all quantities in the factorization formula and use them to predict the large logarithms of order $$ {\alpha \alpha}_s^2{L}^k $$ αα s 2 L k in the three-loop decay amplitude, where $$ L=\ln \left(-{M}_h^2/{m}_b^2\right) $$ L = ln − M h 2 / m b 2 and k = 6, 5, 4, 3. We find perfect agreement with existing numerical results for the amplitude and analytical results for the three-loop contributions involving a massless quark loop. On the other hand, we disagree with the results of previous attempts to predict the series of subleading logarithms $$ \sim {\alpha \alpha}_s^n{L}^{2n+1} $$ ∼ αα s n L 2 n + 1 .

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Subleading power factorization with radiative functions

Cited by 79 publications

References 226 publications

Next-to-leading power threshold effects for resummed prompt photon production

Next-to-leading power threshold effects for resummed prompt photon production

Next-to-leading power threshold effects for inclusive and exclusive processes with final state jets

Factorization at subleading power and endpoint divergences in h → γγ decay. Part II. Renormalization and scale evolution

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