Physics at the Terascale Helmholtz Gemeinschaft

Theorist of the Month

The "Theorist of the Month" is a concept installed in order to improve the exchange between theory and experiment and to strengthen the theory background of experimental Ph.D. students. The Theorist of the Month will spend about one week at DESY and in this time give one basic seminar on his/her research topic, be available for all kinds of theory questions and discussions, and at the end of his/her stay summarise the discussions and questions of the week.

Current "Theorist of the Month" is Francesco Hautmann (until 3.2.2017)

Francesco Hautmann is staying at DESY until 3.2.2017 .

THURSDAY 2 February 2017, 11:00, SR1

Title: "Color correlations in top quark and jet production in the multi-TeV region"

Abstract: In the theory of boosted top quark and multi-TeV jet production at the LHC and future colliders one of the most challenging topical questions concerns the role of color correlations induced by soft gluons coupling the initial and final states of the high-energy collision. It has been pointed out that such correlations may spoil perturbative QCD factorization theorems and lead to new color entanglement effects. The question arises of whether such effects may be responsible for significant corrections to transverse momentum spectra and angular correlations measured in the multi-TeV region of interest for the LHC and future high-energy experiments. We illustrate these open issues and propose new approaches to the QCD evolution of parton cascades, designed to be well-suited for the treatment of inclusive variables but also of correlations and the analysis of exclusive components of final states in high-energy collisions.


Future "Theorist of the Month"

Next theorist of the month: Valerio Bertone (Vrije Universiteit and NIKEF, Amsterdam, Netherlands) will be at DESY on 13-17 February for the xFitter project.


The xFitter project is an open-source framework devoted to the analysis of high-energy experimental measurements and the assessment of their impact on relevant physical quantities such as Parton Distribution Functions (PDFs) and the strong coupling alpha_s.

The power of the xFitter project stems from its flexibility that in turn is the result of a coordinate effort aimed at developing and joining in one single framework tools for data analysis. The successful employment of xFitter in a large number of analyses testifies its capabilities. On the other hand, due to the contribution of a large number of developers, its complexity is quickly growing. In order to facilitate the maintenance and ensure the functionality, a modular structure able to minimize as much as possible the overlap of different development lines is required.

The objective of this proposal is the development of a modular interface to the functionalities already provided by xFitter. Such an interface will be based on the c++ programming language and will exploit its object-oriented nature to encapsulate independent parts of the code into separate objects managed by dedicated dynamical libraries. The realisation of this proposal is a fundamental step towards an even more flexible and developer-friendly framework allowing for a more ordinate and controllable framework. This will provide the possibility to easily enlarge the set of functionalities of xFitter with the obvious benefit for the scientific community that will have at its disposal an increasingly valuable tool for the interpretation of data.

Theorist of the month in March: Gennady Lykasov will be at DESY on 12-13 March.


Unintegrated PDF and its application to describe the structure functions measured at HERA and the hard processes
studied at LHC.

Past "Theorist of the Month"

Fernando Febres Cordero is staying at DESY from 22-24 April 2015 and can be found in room O2.336 (bldg. 1b, 2nd floor) and he is available on phone 049-40-8998-3525.

THURSDAY 23 April 2015, 16:00, SR1
(coffee & tea served at 15:45pm)

Title: "Processes with Many Jets at the LHC"

Abstract: We study the impact of NLO QCD corrections to processes with many jets at the LHC. We study universal behavior that appears for large enough multiplicity and use it for extrapolating predictions. We show predictions for the 13TeV LHC. As a practical application, we show the BlackHat+Sherpa Ntuple format that allows theorist and experimentalist to access complex fully differential NLO QCD results.


Michael Krämer was staying at DESY from 25 February - 1 March, 2013. His seminar on 28 February was about "Searching for new physics at the Large Hadron Collider: some frustration, but no despair".
   - Slides
   - Poster

Nigel Glover was staying at DESY from 22 - 25 January 2013. His seminar on 24 January was about "Prospects for NNLO measurements using jets at the LHC".
   - Slides
   - Poster

Nikolaos Kidonakis (Kennesaw State University) was staying at DESY from 15 - 21 July 2012. His seminar on 19 July was about Top pair and single top differential cross sections .

John Collins (Penn State) was staying at DESY from 4 - 8 June 2012. His seminar was on a "New definition of Transverse Momentum Dependent parton densities".
   - Poster

Marco Guzzi (Southern Methodist University / CTEQ) was staying at DESY from 23-27 April 2012. In his seminar , he will discussed "Heavy-flavor treatment at NNLO in CTEQ PDF analysis".

Mrinal Dasgupta (University of Manchester) was staying at DESY from 12 - 16 September 2011. His seminar discussed "Theory of QCD jets".
   - Slides
   - Poster

Yuri Dokshitzer (Paris) was staying at DESY from 18 - 22 July 2011. On Thursday, 21 July, he gave a seminar on "Some entertaining aspects of Multiple Parton Interactions physics".
   - Slides

Torbjorn Sjostrand (University of Lund) was staying at DESY from 27 February - 5 March 2011. On Tuesday, March 1, Torbjorn gave a seminar on "Progress on event generation with Pythia 8".

Davison Soper (University of Oregon) was staying at DESY from 8-23 September 2010 and gave a seminar on 20 September 2010: "QCD and Jets".

Fred Olness (SMU) was staying at DESY from 8-12 March 2010. He is one of the key persons of the CTEQ collaboration and in his seminar discussed "W/Z/Higgs Production at LHC and PDF Uncertainties".