Oleksandr Gituliar

Postdoctoral researcher

II. Institut für Theoretische Physik
Universität Hamburg
Luruper Chaussee 149
22761 Hamburg
Germany

Office: 2a/508a
Phone: +49 40 8998 2204
E-mail: oleksandr at gituliar dot net

• Curriculum Vitae
• Publication list from INSPIRE
• Scientific events I have attended (tracked mainly for sentimental reasons).

Research Interests

• Quantum Chromodynamics
• Symbolic Computation
• Feynman Integrals
• Differential Equations for Feynman Integrals

Open-Source Software

Selected projects at http://github.com/gituliar:

• Fuchsia (2017)
• me2to3 (2017)
• Axiloop (2015)

Teaching

• CAPP 2017 School, DESY, Hamburg (Germany)
  Introduction to Differential Equations for Feynman Integrals

Research Projects

In focus

• Fuchsia — a tool for reducing differential equations for Feynman master integrals to the epsilon form.

  Publications:

  • O.Gituliar, V.Magerya
    Fuchsia: a tool for reducing differential equations for Feynman master integrals to epsilon form
    Comput. Phys. Commun. 219 (2017) 329–338, arXiv:1701.04269

  Conference talks:

  • 2018-01-13, “FFC Mini Workshop”, CERN, Geneva (Switzerland)
    Fuchsia and differential equation for multi-scale master integrals
    

  • 2017-09-07, “Matter to the Deepest”, Podlesice (Poland)
    Fuchsia and master integrals for energy-energy correlations at NLO in QCD
    

  • 2016-09-28, “Rethinking Quantum Field Theory” DESY Theory Workshop, Hamburg (Germany)
    Progress in constructing epsilon form of differential equations for master integrals with Fuchsia
    

  • 2016-04-26, Loops and Legs in Quantum Field Theory, Leipzig (Germany)
    Fuchsia and master integrals for splitting functions from differential equations in QCD
    PoS LL2016 [arXiv:1607.00759]

Suspended

• Back in 2014 I started to calculate QCD time-like splitting functions at NNLO from the electron-positron annihilation process. (I have also completed preliminary calculations at NLO.) It turned out that to obtain a final result I need to calculate hundreds of Feynman integrals, a task that one can hardly solve manually. In order to automate it, I started work on Fuchsia and suspended the initial plans. With time Fuchsia became an independent project and took a major fraction of my time. I hope eventually to resume my calculations at some point.

  Publications:

  • O.Gituliar
    Master Integrals for Splitting Functions from Differential Equations in QCD
    JHEP 1602 (2016) 017 [arXiv:1512.02045]

  Conference talks:

  • 2015-06-15, Radcor-Loopfest Symposium, Los Angeles (USA)
    Higher-Order Corrections to the Splitting Functions from Differential Equations in QCD
    PoS RADCOR2015 [arXiv:1601.03657]

  • 2015-01-10, Cracow Epiphany Conference, Cracow (Poland)
    Towards Three-Loop QCD Corrections to the Time-Like Splitting Functions
    Acta Phys.Polon. B46, 1279 (2015) [arXiv:1505.02901]

  • 2014-11-16, LHCPhenoNet Final Meeting, Berlin (Germany)
    Higher-Order Corrections in QCD Evolution Equations and Tools for Their Calculation

Completed

• Acapulco was focused at calculating transverse-momentum-dependent splitting functions at leading order in QCD. The goal was achieved, but there are still many promising ideas left to investigate…

  Publications:

  • O.Gituliar, M.Hentschinski, K.Kutak
    Transverse-Momentum-Dependent Quark Splitting Functions in kt-Factorization: real contributions
    JHEP 1601 (2016) 181 [arXiv:1511.08439]

  Conference talks:

  • 2016-01-07, Cracow Epiphany Conference, Cracow (Poland)
    Splitting Functions for High-Energy Factorization
    Acta Phys.Polon. B47, 1667 (2016) [pdf]

• Axiloop package was written as my PhD project. It calculates one-loop contributions to the collinear splitting functions in QCD. Calculations are based on the Curci-Furmanski-Petronzio approach (details here) where the authors work in the light-cone axial gauge. In this gauge a new type of propagators appears — linear propagators — which introduce spurious (unphysical) singularities to the loop integrals. To overcome this issue and regularize singularities of this type we have developed a new regularization prescription with very nice properties.

  Publications:

  • O.Gituliar
    Higher-Order Corrections in QCD Evolution Equations and Tools for Their Calculation
    PhD thesis [arXiv:1403.6897]

  • O.Gituliar, S.Jadach, A.Kusina, M.Skrzypek
    On Regularizing the Infrared Singularities in QCD NLO Splitting Functions with the New Principal Value Prescription
    Phys. Lett. B732 (2014) 218 [arXiv:1401.5087]

  Conference talks:

  • 2014-06-05, LHCPhenoNet Workshop on Particle Physics, Paris (France)
    Higher-Order Corrections in QCD Evolution Equations and Tools for Their Calculation

  • 2014-01-09, Cracow Epiphany Conference, Cracow (Poland)
    Calculation of QCD NLO Splitting Functions in the light-cone gauge: new regularization prescription
    Acta Phys. Polon. B45, 1361 (2014) [arXiv:1406.4283]

  • 2013-09-06, Matter to the Deepest, Ustron (Poland)
    Virtual Corrections to the NLO Splitting Functions for Monte Carlo: non-singlet case
    Acta Phys. Polon. B44, 2197 (2013) [arXiv:1310.7537]

  • 2012-09-05, High Precision for Hard Processes Workshop, Munich (Germany)
    Axiloop: a tool for the symbolic calculation of splitting kernels at higher orders