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Transcript of LoopFest 2013 Summary Talk L. DixonLoopFest 2013 Summary 1 Lance Dixon (SLAC) Florida State...
LoopFest 2013 Summary Talk
L. Dixon LoopFest 2013 Summary 1
Lance Dixon (SLAC)Florida State University Tallahassee
May 15, 2013
Apologies in advance
• For skipping your favorite topic• For mangling the main point of your
presentation• For a certain chronological bias…
L. Dixon LoopFest 2013 Summary 2
Voyages of Discovery
• 500 Years Ago (April 2, 1513): Ponce de Leon discovers Florida
L. Dixon LoopFest 2013 Summary 3
Voyages of Discovery
• 1 Year Ago (July 4, 2012): ATLAS + CMS discover a bump at 125.5 GeV
L. Dixon LoopFest 2013 Summary 4
Korytov
How fast things change
• Higgs mass: a new precision parameter of SM
L. Dixon LoopFest 2013 Summary 5
Korytov
Can we use a precisemH(gg) – mH(ZZ)to learn about Higgs width?
Li
Also great progress on signal strength m’s
• Denominator = sSM x BrSM needed lots of theory already, e.g. sNNLO; more needed for LHC Run II
L. Dixon LoopFest 2013 Summary 6
Korytov
sHtot: NNLO N3LO first steps
• Convolution of splitting kernels
• Best performed
in Mellin space
with aid of HPLs,
Hsums, maps:
L. Dixon LoopFest 2013 Summary 8
Hoff
sHtot: NNLO N3LO first steps
• Soft limit (z 1)• Use “reverse unitarity”[Anastasiou, Melnikov]
• IBPs
turn MB integrals
into generalized
polylogs z(n)
L. Dixon LoopFest 2013 Summary 9
Dulat
Need more exclusive results
• Especially for WW (jet veto against top)• But also to separate gg, VBF, …
L. Dixon LoopFest 2013 Summary 10
H + 1 jet @ NNLO
• A successful marriage [Czakon]
of FKS and sector decomposition
• gg only so far:• Looking forward to
full results before
complaining about
scale dependence
being too small…
L. Dixon LoopFest 2013 Summary 11
Caola
H + 0 jet @ NNLL’ + NNLO
• SCET-based resummation, uses a global ET veto as intermediate step
L. Dixon LoopFest 2013 Summary 12
Walsh
H + 0 jet @ NNLL + NNLO
L. Dixon LoopFest 2013 Summary 13
Monni
Fairly close to previous plot at 25-30 GeV?
H + 1 jet exclusive
• Resum first for pTjet >> pT
veto
• Match to fixed order for pTjet ~ pT
veto
L. Dixon LoopFest 2013 Summary 14
Liu
H + 2 jets with central veto (VBF)
• HEJ based on high-energy factorization.• Very different from other programs for these cuts
– need to resolve, maybe using V+jets data?
L. Dixon LoopFest 2013 Summary 15
Smillie
High Statistics V + jets Data• Tevatron & LHC, expecially recent D0 (W) & ATLAS (Z) • Agreement very good in “bulk” (but not large rapidity, v. small HT)
L. Dixon LoopFest 2013 Summary 16
Paramonov
• Try to use to understand H + jets dynamics better
Speculation: Could this be related to large x pdfs? OwensCharge separated W + jets at LHC would offer opportunity to separate d(x), u(x) at large x
On Higgs Day (Monday)
• Hardly a word about supersymmetry – except virtually…
L. Dixon LoopFest 2013 Summary 17
Zerf
ILC as a Higgs factory
• Higgs @ 1% of total cross section, not 10-10
• e+e- Zh tagged Higgsabsolute Br’s,
total width
L. Dixon LoopFest 2013 Summary 18
Peskin
NNLO for more hadron collider processes!
• For a long time, only color singlet final states available at full NNLO, mostly 2 1 at Born level: H, W, Z, gg
• 2013 will be remembered as the year of 2 2 at NNLO
L. Dixon LoopFest 2013 Summary 19
Top at NNLO• Great performance:• Upgraded energy from 2 TeV to 8 TeV in just one year:
• Already constraining pdfs and stealthy stops:
L. Dixon LoopFest 2013 Summary 20
Mitov
OK for Tevatron
Need for LHC
Wish for NNLO differential distributions for pdf constraints –Huston
Jets @ NNLO
• Adaptation of antenna subtraction method to pp• Another case (like H + 1 jet) of remarkably small
scale variation in a
gluon-only
approximation
L. Dixon LoopFest 2013 Summary 21
Pires
LoopFest 2013 Summary 22
I Know, It’s Only NLO(But I Like It)*
L. Dixon
*With apologies to the Rolling Stones (founded 50 years ago)
LoopFest 2013 Summary 23
The NLO multiplicity frontier:
L. Dixon
Febres Cordero
W + 5 jets
New request from J. Huston:Did we say NLO? We meant NNLO
The NLO flexibility frontier: GoSam
*FKS/dipole subtractions sold separately
• Examples of
pp H + 3 jets @ NLO
pp gg + jet @ NLO
L. Dixon LoopFest 2013 Summary 25
Greiner
The NLO flexibility frontier: OpenLoops
*dipole/FKS/shower sold separately [or get in aMC@NLO]• Marriage of recursion and OPP (or Collier) tensor reduction
• Example:
pp WW*(j) enmn (j) + ...
including MEPS@NLO [SHERPA]
L. Dixon LoopFest 2013 Summary 26
Cascioli
region
The NLO flexibility (final?) frontier: BSM with FeynRules
L. Dixon LoopFest 2013 Summary 27
Degrande
Are analytic calculations of one-loop amplitudes obsolete?
• Not necessarily. NNLO benefits from their excellent numerical stability
• Also, MCFM far from obsolete, all analytic:• tZ• ttW• Zgj, Zgg• H Z g with MEM@NLO• MCFM MCDM?L. Dixon LoopFest 2013 Summary 28
Rontsch Williams
Merging NLO with showers• MC@NLO, POWHEG great – but accuracy
degrades as you add jets within sample• In past year, several implementations of
NLO merging
L. Dixon LoopFest 2013 Summary 29
Hoeche
W + jets
tt + jets
Another route to NLO merging?
• Use MiNLO nodal scale + Sudakov prescription [Hamilton et al.] modified so B+0j recovered without spoiling NLO B+1j
L. Dixon LoopFest 2013 Summary 30
Re
SUSY Shower Merging
• qq @ NLO
• l l @ NLO
L. Dixon LoopFest 2013 Summary 31
GavinHangst
~~
~~ ThierInside the [POWHEG] box,or waiting for the shower?
ttH signal & bkgd in same box
L. Dixon LoopFest 2013 Summary 32
Kardos
Most complexprocess inPOWHEG-BOXframework
Difficult searchchannel!
Importance of independent PDFs mostly agreeing now at NNLO
• For Higgs,
top@LHC:
L. Dixon LoopFest 2013 Summary 34
Huston
Importance of independent PDFs mostly agreeing now at NNLO
• For Drell Yan, VV, slepton pairs, …
L. Dixon LoopFest 2013 Summary 35
Huston
Multi-Loop Integrals
• Will need more complex 2-loop amplitudes as NNLO QCD real radiation techniques have recently matured.
• 2 3 integrals not known yet• Only a few 2 2 integrals known
analytically, rest numerically• EW frontier at fewer legs, but 3 loops and
multiple masses
L. Dixon LoopFest 2013 Summary 37
Freitas
Numerical Multi-loop Integral Tools
• SecDec2.1
L. Dixon LoopFest 2013 Summary 38
Borowka
Landau singularitiesdetected via run time!
• Method for deforming contoursto make numerical integration overloop momenta possible Becker
Analytic Multi-loop Integral Tools
• Simplify IBP relations to identify 2 2 2-loop master integrals
• Adjust master integral basis to simplify differential equations arising from IBPs pure transcendental functions
L. Dixon LoopFest 2013 Summary 39
Henn
Schabinger
Bahamas Billfish Championship
• Trophy: Billfish Championship Ring designed by Monica Higgs
• Winner = Proud Angler Higgs Bos’n?L. Dixon LoopFest 2013 Summary 40
Summary of summary• It’s been a very stimulating and rewarding 3 days – lots
of great talks representing advances in loop calculation and allied fields across many fronts.
• A great time to be doing precision work for use at LHC.• Most importantly, thanks to those who made this meeting
possible and run so smoothly!• FSU: College of Arts & Sciences, Office of Research,
and Physics Department• Seth Quackenbush• Kathy Mork• Laura Reina
L. Dixon LoopFest 2013 Summary 41