Inability to find justification of a $k_T$-factorization formula by following chains of citations

Avsar, Emil; Collins, John C.

doi:10.48550/arxiv.1209.1675

Cited by 4 publications

(13 citation statements)

References 29 publications

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“…( 62) into Eq, ( 31) and applying the minimal kinematical approximations of Eqs. (38)(39)(40), one immediately recovers the structure in Eq. (37).…”

Section: Maximally General Tmd-factorization At the Amplitude Levelmentioning

confidence: 59%

“…( 51), we now apply the minimal partonic approximations of Eqs. (38)(39)(40). Specifically, we neglect the smallest (order ∼ Λ 2 /Q) momenta k − 1 and k + 2 everywhere except within their own respective parent subgraphs, L(P 1 ; k 1 ) and U(P 2 ; k 2 ).…”

Section: Tree Level Tmd-factorizationmentioning

confidence: 99%

“…The use of the kinematical approximations in Eqs. (38)(39)(40) is symbolized by the "hats" on H LO . After the second equality in Eq.…”

Section: Tree Level Tmd-factorizationmentioning

confidence: 99%

“…The concept of a TMD PDF, and especially of an unintegrated gluon PDF, also appears in extensions of small coupling perturbation theory to the limit of small-x where other novel phenomena such as parton saturation become relevant. In this context, however, there are varying methods for using TMD gluon PDFs in calculations, and work is still needed to fully reconcile the different approaches with one another [24,25,39,40].…”

Section: Introductionmentioning

confidence: 99%

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Extra spin asymmetries from the breakdown of transverse-momentum-dependent factorization in hadron-hadron collisions

Rogers

2013

Phys. Rev. D

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We demonstrate that partonic correlations that would traditionally be identified as subleading on the basis of a generalized TMD-factorization conjecture can become leading-power because of TMD-factorization breaking that arises in hadron-hadron collisions with large transverse momentum back-to-back hadrons produced in the final state. General forms of TMD-factorization fail for such processes because of a previously noted incompatibility between the requirements for TMDfactorization and the Ward identities of non-Abelian gauge theories. We first review the basic steps for factorizing the gluon distribution and then show that a conflict between TMD-factorization and the non-Abelian Ward identity arises already at the level of a single extra soft or collinear gluon when the partonic subprocess involves a TMD gluon distribution. Next we show that the resulting TMDfactorization violating effects produce leading-power final state spin asymmetries that would be classified as subleading in a generalized TMD-factorization framework. We argue that similar extra TMD-factorization breaking effects may be necessary to explain a range of open phenomenological QCD puzzles. The potential to observe extra transverse spin or azimuthal asymmetries in future experiments is highlighted as their discovery may indicate an influence from novel and unexpected large distance parton correlations.

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“…( 62) into Eq, ( 31) and applying the minimal kinematical approximations of Eqs. (38)(39)(40), one immediately recovers the structure in Eq. (37).…”

Section: Maximally General Tmd-factorization At the Amplitude Levelmentioning

confidence: 59%

Section: Tree Level Tmd-factorizationmentioning

confidence: 99%

“…The use of the kinematical approximations in Eqs. (38)(39)(40) is symbolized by the "hats" on H LO . After the second equality in Eq.…”

Section: Tree Level Tmd-factorizationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Extra spin asymmetries from the breakdown of transverse-momentum-dependent factorization in hadron-hadron collisions

Rogers

2013

Phys. Rev. D

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“…Hence, in the dilute limit at low-x where Eq. (A.69) holds, the unintegrated gluon PDF and the Weizsäcker-Williams gluon TMD are equal up to a factor π [31]. In the appropriate gauge, both can be shown to be equal (up to the same factor π) to the gluon number counting operator evaluated in the CGC average.…”

Section: A Appendicesmentioning

confidence: 84%

Photoproduction of three jets in the CGC: gluon TMDs and dilute limit

Altinoluk,

Boussarie,

Marquet

et al. 2020

Preprint

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We study the process γA → q qg + X in the Color Glass Condensate (CGC) effective theory. After obtaining the cross section, we consider two kinematic limits which are encompassed in our result. In the so-called correlation limit, the vector sum of the transverse momenta of the three outgoing particles is small with respect to the individual transverse momenta; the cross section then simplifies considerably and can be written in a factorized form, sensitive to both the unpolarized and linearly-polarized Weizsäcker-Williams transverse momentum dependent gluon distribution function (gluon TMD). The second limit of the CGC cross section that we consider is the dilute limit, which we obtain after performing a weak-field expansion; we recover a typical linear-regime expression, involving a single unintegrated gluon distribution function. Using numerical simulations of the small-x QCD evolution of the TMDs, we investigate the rapidity dependence of the cross section in the correlation limit.

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Dynamical entropy of dense QCD states

Peschanski

2013

Phys. Rev. D

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We discuss dense states of QCD matter formed in high-energy hadronic and heavy-ion collisions from the point of view of statistical physics of non-equilibrium processes. For this sake, we first propose a formulation of the dynamical entropy of dense QCD states in the "saturation regime" leading to a color glass condensate (CGC). The statistical physics description amounts to describe the modification of the color correlation length with energy as a compression process for which non equilibrium thermodynamic properties are applicable. We derive an expression of the dynamical entropy in terms of the rapidity evolution of the unintegrated gluon distributions in the colliding nuclei, verifying suitable positivity and irreversibility properties. We extend this approach to the initial pre-equilibrium (glasma) state of an heavy-ion collision. It allows for a definition of the initial entropy before the evolution towards the hydrodynamic regime as a function of the glasma correlation length and an overlap parameter characterizing the low-momentum spectrum of the glasma state. This initial entropy, by extension to the N=4 SYM theory, is then matched as the key input parameter to the strong coupling evaluation of thermalization towards the hydrodynamic regime based on the AdS/CFT correspondence. It thus allows to cast a bridge between the weak and strong coupling phases of an heavy-ion reaction.Comment: Version mildly updated to match publication. Adding a discussion of the k_T factorization formula. Results and conclusions unchange

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Inability to find justification of a $k_T$-factorization formula by following chains of citations

Cited by 4 publications

References 29 publications

Extra spin asymmetries from the breakdown of transverse-momentum-dependent factorization in hadron-hadron collisions

Extra spin asymmetries from the breakdown of transverse-momentum-dependent factorization in hadron-hadron collisions

Photoproduction of three jets in the CGC: gluon TMDs and dilute limit

Dynamical entropy of dense QCD states

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