Threshold Logarithms Beyond Leading Power

25 Jan 2016, 08:00 → 28 Jan 2016, 18:00 UTC

Higgs Centre for Theoretical Physics

Monday 25 January

09:30 → 10:30 Factorization in the Soft Collinear Effective Theory Beyond Leading Power

In this talk I will describe the methods used in SCET to describe power suppressed amplitudes and factorized hard, jet, and soft functions.  I'll also discuss applications to threshold resummation.

Speaker: Prof. Iain Stewart (MIT)

10:30 → 11:00 Coffee

11:00 → 12:00 Discussion

12:00 → 14:00 Lunch

14:00 → 14:45 Threshold logarithms beyond leading power in perturbative QCD

Speaker: Prof. Lorenzo Magnea (University of Turin)

14:45 → 15:30 Discussion

15:30 → 16:00 Coffee

16:00 → 16:45 Helicity Operators in SCET

I will present an easy-to-use helicity operator basis in soft-collinear effective theory (SCET), for which the hard Wilson coefficients from matching QCD onto SCET are directly given in terms of color-ordered helicity amplitudes. This allows one to seamlessly combine fixed-order helicity amplitudes at any order they are known with a resummation of higher-order logarithmic corrections. I will illustrate this by a few examples and discuss the role of renormalization schemes with helicities in 4- and d-dimensions, and discrete symmetries. The corresponding subleading operators will be introduced in a separate talk by Ian Moult.

Speaker: Dr Wouter Waalewijn (University of Amsterdam)

16:45 → 17:30 Discussion

Tuesday 26 January

09:30 → 10:30 Next-to-leading power factorization with position-space SCET

I review position-space SCET as a framework to address next-to-leading power effects and discuss the following applications: semi-inclusive DIS on a heavy quark, the LBKD amplitude at tree level, and resummation of the three-body heavy quark currents.

Speaker: Prof. Martin Beneke (TUM, Munich)

10:30 → 11:00 Coffee

11:00 → 12:00 Discussion

12:00 → 14:00 Lunch

14:00 → 14:45 A Factorisation Approach to Soft Radiation in Drell-Yan Beyond Leading Power

Speaker: Dr Leonardo Vernazza (University of Edinburgh)

14:45 → 15:30 Discussion

15:30 → 16:00 Coffee

16:00 → 16:45 Subleading Soft Theorems in SCET

Using factorization properties of soft-collinear effective theory, I will discuss the construction of soft theorems at subleading power.  Soft gluon emission in SCET is described by operators and Lagrangians whose form is dictated by the reparametrization invariance of the effective theory.  In explicit examples, I will demonstrate how collinear emissions affect the soft theorems and their generalization to one-loop as predicted by SCET.

Speaker: Dr Andrew Larkoski (Harvard University)

16:45 → 17:30 Discussion

Wednesday 27 January

09:30 → 10:30 Soft Expansion by Region and Higgs Production

I will discuss the apllication of the method of expansion by region to obtain soft expansions of loop integrals required in Higgs Production beyond leading order.

Speaker: Dr Franz Herzog (Nikhef, Amsterdam)

10:30 → 11:00 Coffee

11:00 → 12:00 Discussion

12:00 → 14:00 Lunch

14:00 → 14:45 TBA

Speaker: Mr Ian Moult (MIT)

14:45 → 15:30 Discussion

15:30 → 16:00 Coffee

16:00 → 16:45 Resummation from the D-dimensional structure of unfactorized cross section

For inclusive enough processes, the structure of unfactorized parsonic cross sections, together with constraints from mass-factorization theorems, allows the resummation of logarithms beyond the leading power. I present the application of this method to the off-diagonal parsonic cross section of inclusive Higgs production and Drell-Yan, as well as to the off-diagonal splitting functions and the corresponding coefficient functions in inclusive deep-inelastic scattering and semi-inclusive electron-positron annihilation.

Speaker: Dr Adriano Lo Presti (University of Zurich)

16:45 → 17:30 Discussion

Thursday 28 January

09:30 → 10:30 (Next-to) soft effects in gravity

In QCD, (next-to) soft physics is important for improving collider physics predictions. However, there are also a number of reasons for exploring similar effects in gravity. This talk will review the structure of soft and next-to-soft corrections in gravity, and focus on a number of recent applications, including the relationship between Yang-Mills and gravity amplitudes; the next-to-soft theorems of Cachazo and Strominger and their possible role in black hole physics; and transplanckian scattering.

Speaker: Dr Chris White (University of Glasgow)

10:30 → 11:00 Coffee

11:00 → 12:00 Round Table