scholarly journals Relating transverse-momentum-dependent and collinear factorization theorems in a generalized formalism

2016 ◽  
Vol 94 (3) ◽  
Author(s):  
J. Collins ◽  
L. Gamberg ◽  
A. Prokudin ◽  
T. C. Rogers ◽  
N. Sato ◽  
...  
Keyword(s):  
Transverse Momentum ◽  
Collinear Factorization ◽  
Transverse Momentum Dependent

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

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.

scholarly journals J/ψ meson production in SIDIS: matching high and low transverse momentum

2020 ◽  
Vol 2020 (9) ◽  
Author(s):  
Daniël Boer ◽  
Umberto D’Alesio ◽  
Francesco Murgia ◽  
Cristian Pisano ◽  
Pieter Taels
Keyword(s):  
Transverse Momentum ◽  
Meson Production ◽  
Distance Matrix ◽  
Inelastic Electron ◽  
High Transverse Momentum ◽  
Shape Functions ◽  
Long Distance ◽  
Collinear Factorization ◽  
Transverse Momentum Dependent ◽  
Gluon Distributions

Abstract We consider the transverse momentum spectrum and the cos 2ϕ azimuthal distribution of J/ψ mesons produced in semi-inclusive, deep-inelastic electron-proton scattering, where the electron and the proton are unpolarized. At low transverse momentum, we propose factorized expressions in terms of transverse momentum dependent gluon distributions and shape functions. We show that our formulae, at the order αs, correctly match with the collinear factorization results at high transverse momentum. The latter are computed at the order $$ {\alpha}_s^2 $$ α s 2 in the framework of nonrelativistic QCD (NRQCD), with the inclusion of the intermediate $$ {}^3{S}_1^{\left[1\right]} $$ 3 S 1 1 color-singlet Fock state, as well as the subleading color-octet ones that are relatively suppressed by a factor v4 in the NRQCD velocity parameter v. We show that the $$ {}^1{S}_0^{\left[8\right]} $$ 1 S 0 8 and $$ {}^3{P}_J^{\left[8\right]} $$ 3 P J 8 (J = 0, 1, 2) contributions diverge in the small transverse momentum region and allow us to determine the perturbative tails of the shape functions, which carry the same quantum numbers. These turn out to be identical, except for the overall magnitude given by the appropriate NRQCD long distance matrix element.

Transverse Single-Spin Asymmetries in Proton-Proton Collisions Within Collinear Factorization

2015 ◽  
Vol 37 ◽  
pp. 1560033
Author(s):  
Daniel Pitonyak ◽  
Koichi Kanazawa ◽  
Yuji Koike ◽  
Andreas Metz
Keyword(s):  
Transverse Momentum ◽  
Heavy Ion ◽  
High Transverse Momentum ◽  
Relativistic Heavy Ion Collider ◽  
Collinear Factorization ◽  
Transverse Momentum Dependent ◽  
Spin Asymmetries ◽  
Single Spin ◽  
Single Spin Asymmetries ◽  
Azimuthal Asymmetries

We provide a new analysis within collinear factorization of transverse single-spin asymmetries (TSSAs) in high transverse momentum charged and neutral pion production in pp collisions at the Relativistic Heavy Ion Collider (RHIC). This study incorporates the so-called twist-3 fragmentation term and shows that one can describe RHIC data through this mechanism. Moreover, by fixing other non-perturbative inputs through extractions of transverse momentum dependent functions in e+e- → h1h2X and semi-inclusive deep-inelastic scattering (SIDIS), we provide for the first time a consistency between certain spin/azimuthal asymmetries in all three reactions (i.e., pp, e+e-, and SIDIS).

scholarly journals CASCADE3 A Monte Carlo event generator based on TMDs

2021 ◽  
Vol 81 (5) ◽  
Author(s):  
S. Baranov ◽  
A. Bermudez Martinez ◽  
L. I. Estevez Banos ◽  
F. Guzman ◽  
F. Hautmann ◽  
...  
Keyword(s):  
Monte Carlo ◽  
Transverse Momentum ◽  
Parton Shower ◽  
Monte Carlo Event ◽  
Event Generator ◽  
Initial State ◽  
Collinear Factorization ◽  
Transverse Momentum Dependent ◽  
Monte Carlo Event Generator ◽  
Parton Showering

AbstractThe Cascade3 Monte Carlo event generator based on Transverse Momentum Dependent (TMD) parton densities is described. Hard processes which are generated in collinear factorization with LO multileg or NLO parton level generators are extended by adding transverse momenta to the initial partons according to TMD densities and applying dedicated TMD parton showers and hadronization. Processes with off-shell kinematics within $$k_{{t}}$$ k t -factorization, either internally implemented or from external packages via LHE files, can be processed for parton showering and hadronization. The initial state parton shower is tied to the TMD parton distribution, with all parameters fixed by the TMD distribution.

scholarly journals Factorization of e+e− → H X cross section, differential in zh, PT and thrust, in the 2-jet limit

2021 ◽  
Vol 2021 (2) ◽  
Author(s):  
M. Boglione ◽  
A. Simonelli
Keyword(s):  
Transverse Momentum ◽  
Cross Section ◽  
Belle Collaboration ◽  
Hadron Production ◽  
Leading Order ◽  
Transverse Momentum Dependent ◽  
Factorization Scheme ◽  
Phenomenological Studies ◽  
Cross Section Differential ◽  
Perturbative Part

Abstract Factorizing the cross section for single hadron production in e+e− annihilations is a highly non trivial task when the transverse momentum of the outgoing hadron with respect to the thrust axis is taken into account. We work in a scheme that allows to factorize the e+e−→ H X cross section as a convolution of a calculable hard coefficient and a Transverse Momentum Dependent (TMD) fragmentation function. The result, differential in zh, PT and thrust, will be given to all orders in perturbation theory and explicitly computed to Next to Leading Order (NLO) and Next to Leading Log (NLL) accuracy. The predictions obtained from our computation, applying the simplest and most natural ansatz to model the non-perturbative part of the TMD, are in exceptional agreement with the experimental measurements of the BELLE Collaboration. The factorization scheme we propose relates the TMD parton densities defined in 1-hadron and 2-hadron processes, restoring the possi- bility to perform global phenomenological studies of TMD physics including experimental data from semi-inclusive deep inelastic scattering, Drell-Yan processes, e+e−→ H1H2X and e+e−→ H X annihilations.

scholarly journals PHENOMENOLOGY OF THE SIVERS EFFECT WITH TMD EVOLUTION

2012 ◽  
Vol 20 ◽  
pp. 145-152
Author(s):  
M. ANSELMINO ◽  
M. BOGLIONE ◽  
S. MELIS
Keyword(s):  
Transverse Momentum ◽  
Evolution Equations ◽  
Distribution Functions ◽  
Dependent Data ◽  
Clear Indication ◽  
Transverse Momentum Dependent ◽  
Sidis Data ◽  
Sivers Function ◽  
Theoretical Developments

Recently, theoretical developments have led to the QCD evolution equations for the unpolarized Transverse Momentum Dependent (TMD) distribution functions and for the Sivers function (TMD-evolution). We tested whether the proposed TMD-evolution can already be observed in the SIDIS data on the Sivers asymmetry. Although very preliminary, our analysis shows that data are compatible with such an evolution with a clear indication of evolution in the x-dependent data subsets.

scholarly journals Transverse-momentum-dependent parton distributions up to N3LL from Drell-Yan data

2020 ◽  
Vol 2020 (7) ◽  
Author(s):  
Alessandro Bacchetta ◽  
Valerio Bertone ◽  
Chiara Bissolotti ◽  
Giuseppe Bozzi ◽  
Filippo Delcarro ◽  
...  
Keyword(s):  
Transverse Momentum ◽  
Parton Distributions ◽  
Transverse Momentum Dependent
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