Fermionic Glauber operators and quark reggeization

Moult, Ian; Solon, Mikhail P.; Stewart, Iain W.; Vita, Gherardo

doi:10.1007/jhep02(2018)134

Cited by 31 publications

(54 citation statements)

References 83 publications

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“…Expressions for the coefficients in terms of scalar integrals look as follows: (39)), the ∆B [−] (Q 2 , q − )-term cancels between this two integrals due to Eq. (34). As a result, no power divergences or O(r ± )-terms is left and the only rapidity divergence in one-loop correction to the Γ…”

Section: One-loop Correction To the Qγ Q-vertexmentioning

confidence: 99%

Computing one-loop corrections to effective vertices with two scales in the EFT for Multi-Regge processes in QCD

Nefedov

2019

Nuclear Physics B

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The computation of one-loop corrections to Reggeon-Particle-Particle effective vertices with two scales of virtuality is considered in the framework of gauge-invariant effective field theory for Multi-Regge processes in QCD. Rapidity divergences arising in loop integrals are regulated by "tilted Wilson lines" prescription. General analysis of rapidity divergences at one loop is given and necessary scalar integrals with one and two scales of virtuality are computed. Two examples of effective vertices at one loop are considered: the effective vertex of interaction of (space-like) virtual photon with one Reggeized and one Yang-Mills quark and the effective vertex of Reggeized gluon to Yang-Mills gluon transition with an insertion of the operator tr [G µν G µν ] carrying the (space-like) off-shell momentum. All terms ∼ r ± in the rapidity-regulator variable r cancel between diagrams and only log r-divergence is left. It is checked on several examples, that obtained results indeed allow one to reproduce Regge limit of one-loop QCD scattering amplitudes.(NLLA) [28,29,30]. It is natural to ask for the systematic tool, which makes this property of QCD scattering amplitudes manifest. The gauge-invariant Effective Field Theory (EFT) for Multi-Regge processes in QCD [31,32] is such a tool. In the original papers [31,32], the Reggeization of gluon and quark was shown to hold in a framework of EFT in the LLA. Computing loop corrections in this EFT one finds a new type of divergences of loop integrals, the so-called rapidity divergences, which will be discussed in the forthcoming sections of the present paper. Similar divergences also arise in the context of Soft-Collinear Effective Theory (SCET) 1 [35,36] and Transverse-Momentum-Dependent (TMD) factorization [37,38] and several prescriptions to regularize them, such as analytic regularization [35], δ-regularization [39] and "tilted Wilson lines" regularization [37,38] where introduced in the literature. Among mentioned prescriptions, only the last one does not modify the standard definition of the Wilson lines, and therefore it can be relatively straightforwardly applied to the High-Energy EFT [31,32]. First such applications where performed in the Refs. [40,41,42] where one-loop corrections to the propagator of Reggeized gluon and effective vertices of interaction of on-shell quark and gluon with one Reggeized gluon where computed in the framework of EFT, and found to be consistent with the results obtained earlier from QCD. Later, the two-loop Regge trajectory of a gluon was extracted from a rapidity-divergent part of the two-loop correction to a Reggeized gluon propagator in the EFT [43] and it coincides with known QCD result. Also, the calculation of the one-loop correction to the propagator of Reggeized quark (Q) and vertex of interaction of on-shell photon with one Reggeized and one QCD quark (Qγq-vertex) has been done in the Ref. [44] and it was shown, that this results allow one to reproduce the Multi-Regge asymptotics of the positive-signature part of the one-loop QC...

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Section: One-loop Correction To the Qγ Q-vertexmentioning

confidence: 99%

Computing one-loop corrections to effective vertices with two scales in the EFT for Multi-Regge processes in QCD

Nefedov

2019

Nuclear Physics B

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“…First, while at leading power, rapidity divergences arise only from gluons, at subleading power rapidity divergences can arise also from soft quarks. Soft quarks have also been rapidityregulated to derive the quark Regge trajectory [117]. Here, since we consider only the case of a single real emission crossing the cut, this simply means that we must regulate both quarks and gluons.…”

Section: Rapidity Regularization At Subleading Powermentioning

confidence: 99%

Subleading power rapidity divergences and power corrections for qT

Ebert

Moult

Stewart

et al. 2019

J. High Energ. Phys.

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141

182

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A number of important observables exhibit logarithms in their perturbative description that are induced by emissions at widely separated rapidities. These include transverse-momentum (q T ) logarithms, logarithms involving heavy-quark or electroweak gauge boson masses, and small-x logarithms. In this paper, we initiate the study of rapidity logarithms, and the associated rapidity divergences, at subleading order in the power expansion. This is accomplished using the soft collinear effective theory (SCET). We discuss the structure of subleading-power rapidity divergences and how to consistently regulate them. We introduce a new pure rapidity regulator and a corresponding MS-like scheme, which handles rapidity divergences while maintaining the homogeneity of the power expansion. We find that power-law rapidity divergences appear at subleading power, which give rise to derivatives of parton distribution functions. As a concrete example, we consider the q T spectrum for colorsinglet production, for which we compute the complete q 2 T /Q 2 suppressed power corrections at O(α s ), including both logarithmic and nonlogarithmic terms. Our results also represent an important first step towards carrying out a resummation of subleading-power rapidity logarithms.

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“…In this paper, we will considerably simplify the structure of the subleading power SCET Lagrangians not involving Glauber exchange, re-organizing them using the equations of motion of the effective theory, and writing them in terms of gauge invariant operators. Subleading power contributions to the Glauber Lagrangian that describe quark reggeization are also known [86].…”

Section: General Formalismmentioning

confidence: 99%

“…A subset of power corrections to the Glauber Lagrangian, namely those giving rise to the Reggeization of the quark, were studied in[86].…”

mentioning

confidence: 99%

Subleading power factorization with radiative functions

Moult

Stewart

Vita

2019

J. High Energ. Phys.

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The study of amplitudes and cross sections in the soft and collinear limits allows for an understanding of their all orders behavior, and the identification of universal structures. At leading power soft emissions are eikonal, and described by Wilson lines. Beyond leading power the eikonal approximation breaks down, soft fermions must be added, and soft radiation resolves the nature of the energetic partons from which they were emitted. For both subleading power soft gluon and quark emissions, we use the soft collinear effective theory (SCET) to derive an all orders gauge invariant bare factorization, at both amplitude and cross section level. This yields universal multilocal matrix elements, which we refer to as radiative functions. These appear from subleading power Lagrangians inserted along the lightcone which dress the leading power Wilson lines. The use of SCET enables us to determine the complete set of radiative functions that appear to O(λ 2 ) in the power expansion, to all orders in α s . For the particular case of event shape observables in e + e − → dijets we derive how the radiative functions contribute to the factorized cross section to O(λ 2 ).

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Fermionic Glauber operators and quark reggeization

Cited by 31 publications

References 83 publications

Computing one-loop corrections to effective vertices with two scales in the EFT for Multi-Regge processes in QCD

Computing one-loop corrections to effective vertices with two scales in the EFT for Multi-Regge processes in QCD

Subleading power rapidity divergences and power corrections for qT

Subleading power factorization with radiative functions

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