scholarly journals Two-loop splitting in double parton distributions: the colour non-singlet case

2021 ◽  
Vol 2021 (8) ◽  
Author(s):  
M. Diehl ◽  
J. R. Gaunt ◽  
P. Plößl
Keyword(s):  
Perturbation Theory ◽  
Leading Order ◽  
Dominant Contribution ◽  
Parton Distributions

Abstract At small inter-parton distances, double parton distributions receive their dominant contribution from the splitting of a single parton. We compute this mechanism at next-to-leading order in perturbation theory for all colour configurations of the observed parton pair. Rapidity divergences are handled either by using spacelike Wilson lines or by applying the δ regulator. We investigate the behaviour of the two-loop contributions in different kinematic limits, and we illustrate their impact in different channels.

scholarly journals Two-loop splitting in double parton distributions

2019 ◽  
Vol 7 (2) ◽  
Author(s):  
Markus Diehl ◽  
Jonathan Gaunt ◽  
Peter Plössl ◽  
Andreas Schafer
Keyword(s):  
Perturbation Theory ◽  
Momentum Space ◽  
Short Distance ◽  
Sum Rules ◽  
Leading Order ◽  
Parton Distributions ◽  
Double Parton Scattering ◽  
Colour Singlet ◽  
Parton Scattering

Double parton distributions (DPDs) receive a short-distance contribution from a single parton splitting to yield the two observed partons. We investigate this mechanism at next-to-leading order (NLO) in perturbation theory. Technically, we compute the two-loop matching of both the position and momentum space DPDs onto ordinary PDFs. This also yields the 1 \to 21→2 splitting functions appearing in the evolution of momentum-space DPDs at NLO. We give results for the unpolarised, colour-singlet DPDs in all partonic channels. These quantities are required for calculations of double parton scattering at full NLO. We discuss various kinematic limits of our results, and we verify that the 1 \to 21→2 splitting functions are consistent with the number and momentum sum rules for DPDs.

scholarly journals Strong CP violation in spin-1/2 singly charmed baryons

2021 ◽  
Vol 2021 (1) ◽  
Author(s):  
Y. Ünal ◽  
Ulf-G. Meißner
Keyword(s):  
Perturbation Theory ◽  
Dipole Moment ◽  
Form Factor ◽  
Cp Violation ◽  
Mass Shell ◽  
Chiral Expansion ◽  
Renormalization Scheme ◽  
Leading Order ◽  
Chiral Perturbation ◽  
Charmed Baryons

Abstract We report on the calculation of the CP-violating form factor F3 and the corresponding electric dipole moment for charmed baryons in the spin-1/2 sector generated by the QCD θ-term. We work in the framework of covariant baryon chiral perturbation theory within the extended-on-mass-shell renormalization scheme up to next-to-leading order in the chiral expansion.

scholarly journals HARD-POMERON BEHAVIOR OF THE LONGITUDINAL STRUCTURE FUNCTION FL IN THE NEXT-TO-LEADING ORDER AT LOW x

2009 ◽  
Vol 18 (01) ◽  
pp. 131-140 ◽  
Author(s):  
G. R. BOROUN
Keyword(s):  
Perturbation Theory ◽  
Structure Function ◽  
Perturbative Qcd ◽  
Gluon Distribution ◽  
Analytic Formula ◽  
Leading Order ◽  
Longitudinal Structure ◽  
Longitudinal Structure Function ◽  
Low X

We present an analytic formula to extract the longitudinal structure function in the next-to-leading order of the perturbation theory at low x, from the Regge-like behavior of the gluon distribution and the structure function at this limit. In this approach, the longitudinal structure function has the hard-Pomeron behavior. The determined values are compared with the H1 data and MRST model. All results can consistently be described within the framework of perturbative QCD, which essentially show increases as x decreases.

GAUGE INDEPENDENCE OF THE FERMION DAMPING RATE IN A HOT PLASMA - LANDAU GAUGE VS COULOMB GAUGE

1993 ◽  
Vol 08 (08) ◽  
pp. 739-748
Author(s):  
H. NAKKAGAWA ◽  
A. NIÉGAWA ◽  
B. PIRE
Keyword(s):  
Perturbation Theory ◽  
Gluon Propagator ◽  
Landau Gauge ◽  
Coulomb Gauge ◽  
Leading Order ◽  
Loop Order ◽  
Hard Thermal Loop ◽  
Hot Plasma ◽  
Damping Rate

The damping rate of a heavy muon/quark in a hot QED/QCD plasma is calculated in the Landau gauge to the effective one-loop order in the resummed perturbation theory of Braaten and Pisarski. For both a muon/quark at rest and in an energetic case we obtain to leading order the same result as in the Coulomb gauge. Resummation of hard-thermal loop corrections to the photon/gluon propagator is of key importance for this gauge independence.

scholarly journals Chiral perturbation theory and nucleon–pion-state contaminations in lattice QCD

2017 ◽  
Vol 32 (15) ◽  
pp. 1730011 ◽  
Author(s):  
Oliver Bär
Keyword(s):  
Perturbation Theory ◽  
Chiral Perturbation Theory ◽  
Distribution Functions ◽  
Leading Order ◽  
Chiral Perturbation ◽  
Parton Distribution Functions ◽  
Physical Point ◽  
Source Sink ◽  
The Impact ◽  
Quark Momentum

Multiparticle states with additional pions are expected to be a non-negligible source of excited-state contamination in lattice simulations at the physical point. It is shown that baryon chiral perturbation theory can be employed to calculate the contamination due to two-particle nucleon–pion-states in various nucleon observables. Leading order results are presented for the nucleon axial, tensor and scalar charge and three Mellin moments of parton distribution functions (quark momentum fraction, helicity and transversity moment). Taking into account phenomenological results for the charges and moments the impact of the nucleon–pion-states on lattice estimates for these observables can be estimated. The nucleon–pion-state contribution results in an overestimation of all charges and moments obtained with the plateau method. The overestimation is at the 5–10% level for source-sink separations of about 2 fm. The source-sink separations accessible in contemporary lattice simulations are found to be too small for chiral perturbation theory to be directly applicable.

HIGH pT JET PRODUCTION IN pp COLLISIONS

1995 ◽  
Vol 10 (20n21) ◽  
pp. 3071-3085 ◽  
Author(s):  
K.J. ESKOLA ◽  
X.-N. WANG
Keyword(s):  
Cross Sections ◽  
Leading Order ◽  
Pp Collisions ◽  
Production Rates ◽  
Parton Distributions ◽  
Jet Production ◽  
Order Calculation ◽  
Jet Cross Sections

Production rates of large pT jets inpp collisions at RHIC and LHC energies are studied using the next-to-leading order calculation of S.D. Ellis, Z. Kunszt and D. Soper. The computed inclusive one-jet cross sections are compared against the CERN and Fermilab jet data from [Formula: see text] and pp collisions. The dependence of the results on the choice of parton distributions and renormalization/factorization scales is investigated.

SCALE DEPENDENCE OF TWIST-3 CORRELATION FUNCTIONS

2011 ◽  
Vol 04 ◽  
pp. 146-156
Author(s):  
Zhong-Bo Kang ◽  
Jian-Wei Qiu
Keyword(s):  
Correlation Functions ◽  
Evolution Equations ◽  
Scale Dependence ◽  
Leading Order ◽  
Coupling Constant ◽  
Parton Distributions ◽  
Spin Asymmetries ◽  
Single Spin ◽  
Single Spin Asymmetries ◽  
Similarities And Differences

In this talk, we introduce two sets of twist-3 quark-gluon correlation functions that are relevant to transverse single spin asymmetries, and present corresponding evolution equations at the leading order in strong coupling constant, αs. The similarities and differences between the evolution of the leading power parton distributions and that of the twist-3 multiparton correlation functions are also discussed.

scholarly journals Two-flavor chiral perturbation theory at nonzero isospin: pion condensation at zero temperature

2019 ◽  
Vol 79 (10) ◽  
Author(s):  
Prabal Adhikari ◽  
Jens O. Andersen ◽  
Patrick Kneschke
Keyword(s):  
Perturbation Theory ◽  
Equation Of State ◽  
Condensed Phase ◽  
Chiral Perturbation Theory ◽  
Chemical Potential ◽  
Tree Level ◽  
Zero Temperature ◽  
Leading Order ◽  
Chiral Perturbation ◽  
Pion Condensation

Abstract In this paper, we calculate the equation of state of two-flavor finite isospin chiral perturbation theory at next-to-leading order in the pion-condensed phase at zero temperature. We show that the transition from the vacuum phase to a Bose-condensed phase is of second order. While the tree-level result has been known for some time, surprisingly quantum effects have not yet been incorporated into the equation of state.  We find that the corrections to the quantities we compute, namely the isospin density, pressure, and equation of state, increase with increasing isospin chemical potential. We compare our results to recent lattice simulations of 2 + 1 flavor QCD with physical quark masses. The agreement with the lattice results is generally good and improves somewhat as we go from leading order to next-to-leading order in $$\chi $$χPT.

Sign in / Sign up

Export Citation Format

Share Document