A model for high energy rho meson leptoproduction based on collinear factorization and dipole models

We investigate the longitudinal and transverse polarized cross-sections of the leptoproduction of the ρ meson in the high energy limit. Our model is based on the computation of the impact factor γ*(λγ)→ ρ (λρ) using the twist expansion in the forward limit which is expressed in the impact parameter space. This treatment involves in the final stage the twist 2 and twist 3 distribution amplitudes (DAs) of the ρ meson and the dipole scattering amplitude. Taking models that exist for the DAs and for the dipole cross-section. We get a phenomenological model for the helicity amplitudes. We compare our predictions with HERA data and get a fairly good description for large enough virtualities of the photon. PACS number(s): 13.60.Le, 12.39.St, 12.38.Bx.

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High-energy resummation in $$\Lambda _c$$ baryon production

The European Physical Journal C ◽

10.1140/epjc/s10052-021-09448-3 ◽

2021 ◽

Vol 81 (8) ◽

Author(s):

Francesco G. Celiberto ◽

Michael Fucilla ◽

Dmitry Yu. Ivanov ◽

Alessandro Papa

Keyword(s):

High Energy ◽

The Novel ◽

Baryon Production ◽

Collinear Factorization ◽

Azimuthal Correlations ◽

Rapidity Distributions

AbstractWe present a study on inclusive emissions of a double $$\Lambda _c$$ Λ c or of a $$\Lambda _c$$ 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 modular interface, suited to the analysis of different semi-hard reactions, employing the novel parameterization for the description of parton fragmentation into $$\Lambda _c$$ 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.

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Intrinsic charm in the nucleon and charm production at large rapidities in collinear, hybrid and kT-factorization approaches

Journal of High Energy Physics ◽

10.1007/jhep10(2020)135 ◽

2020 ◽

Vol 2020 (10) ◽

Author(s):

Rafał Maciuła ◽

Antoni Szczurek

Keyword(s):

Transverse Momentum ◽

High Energy ◽

Charm Production ◽

Leading Order ◽

Collinear Factorization ◽

Factorization Approach ◽

High Energies ◽

Neutrino Production ◽

Intrinsic Charm ◽

Gluon Distributions

Abstract We discuss the role of intrinsic charm (IC) in the nucleon for forward production of c-quark (or $$ \overline{c} $$ c ¯ -antiquark) in proton-proton collisions for low and high energies. The calculations are performed in collinear-factorization approach with on-shell partons, kT-factorization approach with off-shell partons as well as in a hybrid approach using collinear charm distributions and unintegrated (transverse momentum dependent) gluon distributions. For the collinear-factorization approach we use matrix elements for both massless and massive charm quarks/antiquarks. The distributions in rapidity and transverse momentum of charm quark/antiquark are shown for a few different models of IC. Forward charm production is dominated by gc-fusion processes. The IC contribution dominates over the standard pQCD (extrinsic) gg-fusion mechanism of $$ c\overline{c} $$ c c ¯ -pair production at large rapidities or Feynman-xF. We perform similar calculations within leading-order and next-to-leading order kT-factorization approach. The kT-factorization approach leads to much larger cross sections than the LO collinear approach. At high energies and large rapidities of c-quark or $$ \overline{c} $$ c ¯ -antiquark one tests gluon distributions at extremely small x. The IC contribution has important consequences for high-energy neutrino production in the Ice-Cube experiment and can be, to some extent, tested at the LHC by the SHIP and FASER experiments by studies of the ντ neutrino production.

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Particle Production at High Energy: DGLAP, BFKL and Beyond

Universe ◽

10.3390/universe5020064 ◽

2019 ◽

Vol 5 (2) ◽

pp. 64 ◽

Cited By ~ 2

Author(s):

Jamal Jalilian-Marian

Keyword(s):

Evolution Equation ◽

Particle Production ◽

Evolution Equations ◽

High Energy ◽

Color Glass ◽

Collinear Factorization ◽

Perturbative Quantum Chromodynamics ◽

Nuclear Collisions ◽

Perturbative Quantum ◽

Regge Limit

Particle production in high energy hadronic/nuclear collisions in the Bjorken limit Q 2 , s → ∞ can be described in the collinear factorization framework of perturbative Quantum ChromoDynamics (QCD). On the other hand in the Regge limit, at fixed and not too high Q 2 with s → ∞ , a k ⊥ factorization approach (or a generalization of it) is the appropriate framework. A new effective action approach to QCD in the Regge limit, known as the Color Glass Condensate (CGC) formalism, has been developed which allows one to investigate particle production in high energy collisions in the kinematics where collinear factorization breaks down. Here we give a brief overview of particle production in CGC framework and the evolution equation which governs energy dependence of the observables in this formalism. We show that the new evolution equation reduces to previously known evolution equations in the appropriate limits.

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The transverse momentum spectrum of low mass Drell–Yan production at next-to-leading order in the parton branching method

The European Physical Journal C ◽

10.1140/epjc/s10052-020-8136-y ◽

2020 ◽

Vol 80 (7) ◽

Author(s):

A. Bermudez Martinez ◽

P. L. S. Connor ◽

D. Dominguez Damiani ◽

L. I. Estevez Banos ◽

F. Hautmann ◽

...

Keyword(s):

Transverse Momentum ◽

Hadron Collider ◽

Center Of Mass ◽

High Energy ◽

Leading Order ◽

Collinear Factorization ◽

Transverse Momentum Dependent ◽

Momentum Spectra ◽

Transverse Momentum Spectra ◽

Low Mass

Abstract It has been observed in the literature that measurements of low-mass Drell–Yan (DY) transverse momentum spectra at low center-of-mass energies $$\sqrt{s}$$s are not well described by perturbative QCD calculations in collinear factorization in the region where transverse momenta are comparable with the DY mass. We examine this issue from the standpoint of the Parton Branching (PB) method, combining next-to-leading-order (NLO) calculations of the hard process with the evolution of transverse momentum dependent (TMD) parton distributions. We compare our predictions with experimental measurements at low DY mass, and find very good agreement. In addition we use the low mass DY measurements at low $$\sqrt{s}$$s to determine the width $$q_s$$qs of the intrinsic Gauss distribution of the PB-TMDs at low evolution scales. We find values close to what has earlier been used in applications of PB-TMDs to high-energy processes at the Large Hadron Collider (LHC) and HERA. We find that at low DY mass and low $$\sqrt{s}$$s even in the region of $$p_\mathrm{T}/m_\mathrm{DY}\sim 1$$pT/mDY∼1 the contribution of multiple soft gluon emissions (included in the PB-TMDs) is essential to describe the measurements, while at larger masses ($$m_\mathrm{DY}\sim m_{{\mathrm{Z}}}$$mDY∼mZ) and LHC energies the contribution from soft gluons in the region of $$p_\mathrm{T}/m_\mathrm{DY}\sim 1$$pT/mDY∼1 is small.

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