Download presentation
Presentation is loading. Please wait.
Published bySamantha Joseph Modified over 8 years ago
1
I. Scimemi, with Ambar Jain and Iain Stewart, MIT, Cambridge 1 EF07,Paris
2
Extract m t from jet reconstruction with precision “in principle” less than Λ QCD ►Define an observable sensitive to m t ►Identify the physical scales of the problem ►parameterize soft gluons ►calculate perturbative pieces ►Including top’s width effects, Γt~1.4 GeV For the moment we look at Main formalism in the talk of A. Hoang 2 EF07,Paris
3
The relevant scales are Q,m, QCD Fleming, Hoang, Mantry, Stewart ArXiv:0703.207 3 EF07,Paris
4
The main observable is Where And 4 EF07,Paris
5
5
6
We want this at 2 loops Calculable perturbatevely 6 EF07,Paris
7
Most of results for tree-l and 1-L shown by A. Hoang. The calculation of this part now completed=Finite part of 2-loop diagrams. 7 EF07,Paris
8
and In light cone coord. Wilson lines 8 EF07,Paris Note that m j cannot be Msbar otherwise power counting is violated Inclusive in decay productsMass scheme choice
9
Tree level …and 2 loop Wilson lines attach here! Broadhurst, Grozin 9 EF07,Paris
10
The one loop integral have the form The 2 loop integrals have the form (solved with IBP) 10 EF07,Paris
11
The Z(s, ) has the usual expansion in 11 EF07,Paris
12
The 2-loop contribution due to one loop renormalization is obtained with convolutions 12 EF07,Paris
13
The consistency relations now involve convolutions.. 13 EF07,Paris
14
1-loop result 2-loop results 14 EF07,Paris
15
It is possible to express B with a dispersion relation One can calculate B for a stable top quark The RGE are the same for stable and unstable tops The smearing introduces explicitly a new scale 15 EF07,Paris
16
Plot for (s, GeV) and pole mass 16 EF07,Paris Preliminary
17
17 EF07,Paris The position of the peak does not change linearly under evolution
18
EF07,Paris 18 The mass so defined in this way has the correct linear properties when evolving
19
EF07,Paris 19 Plot for (, L=1 GeV) and jet mass
20
Both the MSb mass and the jet mass are renormalon free. The MSb mass is known at 3 loops. Now the jet mass at 2 loops. Numerically the loop corrections to mj are much smaller than the loop corrections to MSb- mass 20 EF07,Paris
21
21 EF07,Paris
22
22 EF07,Paris In order to get the final result one has still to do the convolution with soft function
23
In order to have contact with data we must perform a convolution with a soft function. An interesting model presented recently by A. Hoang and I. Stewart, arXiv0709.3519 The main features are, This model wants to be valid both in the peak region and in the tail. The convolution of J’s and S scale like a local object. For consistency, the renormalon ambiguity in the partonic part and in the jet function should be removed (see A. Hoang talk). 23 EF07,Paris
24
We have analyzed the jet function at 2 loops using EFT. The matching of the jet mass with pole and MSb mass is now ready at 2 loops order, as well as anomalous dimension. For a complete 2 loops result also the partonic part of the soft function should be calculated at the same order. Next Step: The extension of this formalism for LHC top production. 24 EF07,Paris
25
25 EF07,Paris
26
Plot for (, GeV) and jet mass 26 EF07,Paris
Similar presentations
© 2025 SlidePlayer.com. Inc.
All rights reserved.