High-energy resummation in Λc baryon production Celiberto, Francesco G.; Fucilla, Michael; Ivanov, Dmitry Yu ...
The European physical journal. C, Particles and fields,
08/2021, Volume:
81, Issue:
8
Journal Article
Peer reviewed
Open access
We present a study on inclusive emissions of a double
Λ
c
or of a
Λ
c
plus a light-flavored jet system as probe channels in the semi-hard regime of QCD. Our formalism relies on the so-called hybrid ...high-energy/collinear factorization, where the standard collinear description is supplemented by the
t
-channel resummation
à la
BFKL of energy logarithms up to the next-to-leading accuracy. We make use of the JETHAD modular interface, suited to the analysis of different semi-hard reactions, employing the novel KKSS19 parameterization for the description of parton fragmentation into
Λ
c
baryons. We provide predictions for rapidity distributions and azimuthal correlations, that can be studied at current and forthcoming LHC configurations, hunting for possible stabilizing effects of the high-energy series.
A
bstract
The cross-sections of diffractive double hadron photo- or electroproduction with large
p
T
, on a nucleon or a nucleus, are calculated to NLO accuracy. A hybrid formalism mixing collinear ...factorization and high energy small-
x
factorization, more precisely the shockwave formalism for the latter, is used to derive the results. The cancellation of divergences is explicitly shown, and the finite parts of the NLO differential cross-sections are found. We work in arbitrary kinematics such that both photoproduction and leptoproduction are considered. The results are therefore usable, to detect saturation effects, at both the future EIC or already at LHC, using Ultra Peripheral Collisions.
A
bstract
The effective Reggeon-Reggeon-gluon vertex, known as Lipatov vertex, is the key ingredient that allows to develop the BFKL approach in QCD. Within the next-to-leading logarithmic ...approximation, it is sufficient to know its one-loop corrections, in dimensional regularization (
D
= 4 + 2
ϵ
), up to the constant term in the
ϵ
-expansion. In the next-to-next-to-leading approximation, however, the one-loop Lipatov vertex is needed up to the order
ϵ
2
. In this paper we present the expression for this vertex in dimensional regularization up to the required accuracy.
A
bstract
We calculate the cross-sections of diffractive single hadron photo- or electroproduction with large
p
T
, on a nucleon or a nucleus in the shockwave formalism. We use the hybrid formalism ...mixing collinear factorization with high energy small-
x
factorization with the impact factors computed at next-to-leading order accuracy. We prove the cancellation of divergence and we determine the finite parts of the differential cross-sections. We work in general kinematics such that both photoproduction and leptoproduction are considered. The results can be used to detect saturation effects, at both the future EIC or already at LHC, using Ultra-Peripheral Collisions.
A
bstract
We consider the one-loop effective vertex for the interaction of a gluon with a Reggeized gluon and a Higgs boson in the infinite-top-mass limit, which is described by a dimension-5 ...non-renormalizable operator. This vertex enters the calculation of differential cross sections for the forward inclusive production of a Higgs boson in high-energy proton-proton collisions, possibly in association with a backward jet or identified hadron, in a framework where next-to-leading logarithms of the energy are resummed to all orders. The effective vertex is extracted from the high-energy behavior of two-to-two amplitudes for the Higgs production in parton-parton collisions and relies on the validity of the Regge form for these amplitudes. We find that the usual eikonal approximation (Gribov prescription) for the Regge limit and the known region-expansion technique in this limit lead to an incomplete result for the amplitude. The discrepancy is traced back to the non-renormalizable nature of the involved operator. However, the Regge limit of the exact QCD amplitude agrees with the Regge-pole exchange form at one loop, nontrivially supporting the Reggeization hypothesis.
A
bstract
We calculate the next-to-leading order correction to the impact factor (vertex) for the production of a forward Higgs boson, obtained in the infinite top-mass limit. We present the result ...both in the momentum representation and as superposition of the eigenfunctions of the leading-order BFKL kernel. This impact factor is a necessary ingredient for the description of the inclusive hadroproduction of a forward Higgs in the limit of small Bjorken
x
, as well as for the study of inclusive forward emissions of a Higgs boson in association with a backward identified object.
We investigate the inclusive hadroproduction of a heavy quarkonium (
J
/
ψ
or
Υ
), in association with a light-flavored jet, as a testing ground for the semi-hard regime of QCD. Our theoretical setup ...is the hybrid high-energy and collinear factorization, where the standard collinear approach is supplemented by the
t
-channel resummation of leading and next-to-leading energy logarithms
à la
BFKL. We present predictions for rapidity and azimuthal-angle differential distributions, hunting for stabilizing effects of the high-energy series under higher-order corrections. Our reaction represents an additional channel to test the production mechanisms of quarkonia at high energies and large transverse momenta and to possibly shed light on the transition region from heavy-quark pair production to single-parton fragmentation of
J
/
ψ
and
Υ
states.
After a brief introduction of formal and phenomenological progresses in the study of the high-energy limit of perturbative QCD, we present arguments supporting the statement that the inclusive ...emission of Higgs bosons or heavy-flavored hadrons acts as fair stabilizer of high-energy resummed differential distributions. We come out with the message that the hybrid high-energy and collinear factorization, built in term of the next-to-leading logarithmic resummation
à la
BFKL and supplemented by collinear parton distributions and fragmentation functions, is a valid and powerful tool to gauge the feasibility of precision analyses of QCD in its high-energy limit.
We present recent phenomenological studies, tailored on kinematic configurations typical of current and forthcoming analyses at the LHC, for two novel probe channels of the BFKL resummation of energy ...logarithms. Particular attention is drawn to the behavior of distributions differential in azimuthal angle and rapidity, where significant high-energy effects are expected.
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