Theoretical physics
Eric Laenen
NIKHEF and Utrecht University
Fri. Sept. 23, 2005
RECFA at NIKHEF
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Dutch theory groups
Groningen U.
U. of Amsterdam
Free U., Amsterdam
Free U. of Amsterdam
Utrecht U.
NIKHEF
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Radboud (Nijmegen) U.
Leiden U.
Utrecht U.
Fri. Sept. 23, 2005
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Groningen (RuG)
Groningen (KVI)
M. de Roo [Strings & quantum gravity]
E. Bergshoeff [Strings & quantum gravity]
E. Pallante [Lattice field theory]
[50%]
6 Ph.D.’s, 1 Postdoc
8 papers in 04
2 Ph.D, 1 Postdoc
11 papers in 04
Funding: RuG, FOM, EU networks, INTAS,
Nordic Network
Collaborations: KVI, Utrecht, Cambridge,
Kings’s Coll, Brussels, Leuven, Stanford
Noteworthy:
Pallante starts particle/latticgroup, using
LOFAR BlueGene/L computer
String theory cosmology focus
Fri. Sept. 23, 2005
R. Timmermans [Baryon interactions, chiral PT,
Atomic P violation]
O. Scholten [Nucl. Phys., HE Cosmic rays]
Funding: FOM, RuG, EU networks
Collaborations: VU, Nijmegen, Gent, Osaka,..
Noteworthy:
Workshops at Trento, Seattle
Close contact with TRImP, GSI
More ambitions towards astroparticle physics
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Free University (VU) Amsterdam
Leiden University
P. Mulders [QCD spin ph., proton structure]
D. Boer [QCD spin ph., phase structure]
B. Bakker [Lightfront field th., hadr. Struct.]
A. Achucarro [Topological/NP field theory and
cosmology]
P. van Baal [NP Yang-Mills, lattice, HiSparc]
W. Van Neerven [pert. QCD at colliders]
Lorentz professor [Susskind, Wilczek,
Kadanoff]
[40 %]
3 to 4 Ph.D.’s, 1 to 2 Postdocs
8 papers in 04
[30%]
Funding: VU, FOM, EU
Collaborations: KVI, Torino, Regensburg,
BNL, Imperial, Heidelberg
Noteworthy:
Joint theory Master’s program with UvA
Good contacts with NIKHEF theory, VU Exp.
(Babar/LHCb,HERMES, LISA)
3 to 5 Ph.D’s, 3 to 4 Postdocs
19 papers in 04
Funding: UL, FOM, NOW, EU-RTN, ESF,
other countries
Collaborations: NIKHEF, Cambridge,
Sussex, Berkeley, Madrid, Trinity,
Princeton
Noteworthy:
Workshops at Lorentz Center
Fri. Sept. 23, 2005
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Utrecht
G. ‘t Hooft [quantum physics]
B. de Wit [strings & quantum gravity]
R. Loll [quantum gravity]
J. Ambjorn [quantum gravity]
T. Prokopec [cosmology]
G. Aryutanov [strings & quantum gravity ]
S. Vandoren [strings & quantum gravity]
K. Peeters (‘06) [strings & quantum gravity]
Kramers professor [Ashtekar,..]
[60%]
7 Ph.D’s, 7 Postdocs
33 papers in 04
Funding: UU, FOM, NWO, KNAW, EU,
INTAS
Collaborations: UvA, Groningen, many
abroad
Nijmegen (Radboud U.)
R. Kleiss [collider physics, QFT methods]
W. Beenakker [(B)SM at colliders, EW]
T. Rijken [Baryon interactions]
3 Ph.D.’s
8 papers
Funding: RU, FOM, EU
Collaborations: Athens, DESY, PSI, Osaka
Noteworthy:
Good contacts with NIKHEF theory, and
Nijmegen HEP [ATLAS/D0] and PA
[HiSParc/NAHSA]
Noteworthy:
Summer school, well-attended Master’s
program
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University of Amsterdam (UvA)
R, Dijkgraaf [Strings & quant. gravity, math.]
J. de Boer [Strings & quant. gravity]
E. Verlinde [Strings & quant. Gravity]
F..Bais [Strings & topol. FT]
J. Smit [Lattice FT, cosmology]
K. Skenderis [Strings & quant. Gravity]
M. Taylor-Robinson [Strings & quant. Gravity]
K. Schalm [Strings & quant. Gravity]
C. van Weert [Thermal field theory]
[50%]
NIKHEF
J. Koch [Fin. T. lattice QCD, RHIC phys.]
B. Schellekens [Strings & quant. gravity]
J.W. van Holten [SUSY, Cosmol., HiSPARC]
J. Vemaseren [high order pQCD, FORM]
E. Laenen [pert. QCD, heavy quark physics]
5 Ph.D’s, 2 Postdocs
13 papers in 04
Funding: FOM, UvA, UU
Collaborations: DESY, Durham, Bielefeld,
CERN, Torino,Chennai,Madrid
10 Ph.D.’s, 7 Postdocs
36 papers in 04
Funding: UvA, FOM, NWO, EU
Collaborations: UU,NIKHEF,NBI, Harvard,
CERN, Princeton, Caltech,…
Noteworthy:
Host of National Seminar
Close contact with NIKHEF experiments
Noteworthy:
Spinoza prize for Dijkgraaf;
Highly acclaimed annual summer workshop
on Strings
Outreach
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Nikhef theory group
Activities
•
•
Pursuit of active, wide-ranging research program
Close interaction with NIKHEF experiments
(analyses, Ph.D.’s, ICHEP’02, topical lectures)
• Introduce new theoretical developments to NIKHEF
• Training Master’s, Ph.D. students and postdocs
• Members have professorships at 4 Universities
teaching / exposing students to NIKHEF research
Future funding
•
•
New FOM program with University groups (2007 ?)
EU-RTN networks, NWO, small FOM grants…
Special expertise: FORM (Jos Vermaseren)
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Permanent staff/topic in 5 years from now
Strings & quantum gravity [14]
Groningen (2)
Utrecht (5)
U. of Amsterdam (6)
NIKHEF (1)
Lattice & non-pert. FT [4]
Groningen (1)
KVI-Groningen (2)
Leiden (1)
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Cosmology & PA [3]
Leiden (1)
Utrecht (1)
NIKHEF (1)
High-energy collider physics [6]
NIKHEF (2)
Nijmegen (2)
Free U. (2)
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Theory Ph.D students and postdocs
Ph.D. students
• Total: 40-50, more than half from NL
• 60% continue to postdocs
• Education through Dutch Research School for
Theoretical Physics
Postdocs
• About 20-25
• Mostly non-Dutch
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Dutch Research School for Theoretical Physics
• Offers joint program for education of TH Ph.D. students at 6
universities + NIKHEF via advanced courses
• Two themes: 1. Quantum Field Theory and Elementary Particles
2. Condensed Matter and Statistical Physics
• Organizes biannual 2-day symposium with both themes
• Organizes yearly Winter Schools in Nijmegen.
2 weeks, 4 lecturers, 25-30 1st & 2nd year Ph.D. students. E.g.
2005:
G. ‘t Hooft: Advanced quantum field theory
E. Verlinde: String theory and black holes
S. Weinzierl: Methods in higher order perturbation theory
T. Prokopec: Cosmology
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Theoretical physics
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Key research topics
Strings & quantum gravity
Cosmology & PA
Holography/AdS-CFT
Black hole entropy
Topological strings
Standard Model from strings
String cosmology
Baryogenesis
Domain walls
Cosmic scalar fieds
High-energy collider physics
Lattice & non-pert. field
theory
Calorons
Finite T lattice
Light-front and effective theories
1
I  ,  '/  on lattice
2
Fri. Sept. 23, 2005
Higgs + t-tbar production
Jet production
Color glass
Spin physics
Resummation, top quark physics
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Theory and Experiment
QCD - ATLAS/D0, HERA
PA - Antares/KM3Net
Structure functions
(Next-to-leading order) Monte Carlo’s
Jet physics
Resummation
Cosmic neutrinos
Gravitational waves
Cosmic Rays
Spin - Hermes/Compass
EW - LHC, ILC, LEP
Radiative corrections
Top quark physics
Higgs physics
Transversity
Spin structure functions
Heavy Ions - Alice/STAR
Finite T lattice
Color glass condensate
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Two physics topics
1.
2.
Quantum gravity via causal dynamical triangulations [Loll,
Ambjorn, ..] (Utrecht)
3-loop QCD splitting functions [Vermaseren, Moch, Vogt]
(NIKHEF)
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The Universe from Scratch
[Loll, Jurkiewicz, Ambjorn]
• Minimalist approach to quantum gravity
• No strings etc assumed
Premise
• At very short distances, spacetime fluctuates wildly
• No background spacetime; “the stage itself becomes actor”
Sanity conditions
• Wild geometries at short distance ok
• Einstein GR at larger distance
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Tools: Path Integral
Path integral
Z(gi , g f ) 

e
iS gravity ( path)
paths (i f )
• Genuinely non-perturbative
• Most paths very weird
• Magic of PI: true quantum physics due to
superposition
• Sum over suitable class of geometries
• Sum eventually done on computer
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Tools: Triangulation of spacetime
Represent each spacetime in sum by piecewise flat
geometries
Curvature located at vertices
• Edges all common length
• Sum over gluings
Fri. Sept. 23, 2005
Triangles
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4-simplices
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Inputs
S gravity  
1
Curvature(T )   Volume(T )
GN
S
Usual Euclidean version e  e
produced weird
spacetimes, with strange (Hausdorff) dimensions. Dimension
is dynamical quantity!
iS
Key condition: causal dynamical
triangulations (microcausality)!
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Results
Dimension of spacetime
• Hausdorff dimension: 4!
• Dimension (diffusion) at large scale
• Dimension at short distance
• Glimpse of spacetime near Planck
length?
Quantum cosmology
Scale factor a(t) of Universe
CDT allows expansion
Fri. Sept. 23, 2005
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Second order parton evolution kernels
[Vermaseren, Moch, Vogt]
• Opens gate to 2nd order perturbation theory at LHC
• Marvellous computer algebra tool: FORM
• 3-loop QCD. “Calculation of the decade”
Quick acclaim:
• 200 citations after 1.5 year
• selected Top Article in Nuclear Physics
Earlier, the 4-loop QCD function..
Fri. Sept. 23, 2005
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1, 2, 3 & 4-loop calculators
# colors in QCD (strong interaction)
# quark flavors
(3: “red”, “green” & “blue”)
(6: u-, d-, c-, s-, t- & b-quarks)
FORM
author
Hadronic cross sections and pQCD
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Theoretical cross section:  theor  PDF(x1 , x2 )   hard
Input:
• hard scattering cross section  hard
calculate in perturbative QCD
• parton distribution functions PDF
determine from benchmark data (DIS)
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Evolution kernels
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How well do we know the PDF’s?
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Evolution kernels in QCD perturbation theory
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Heroic effort
• 20 Man-years
• 1M lines of FORM code
• Several CPU years
• 10K diagrams, 100K integrals
Scale dependence at NNLO
much better…
First NNLO PDF sets appearing
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A corolllary (Moch, Vogt)..
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Prospects for Dutch theoretical physics
Staff
• A number of retirements coming up. Some positions prefilled.
• Strings & quantum gravity effort strong, young
• Cosmology & astroparticle physics smallish
• Phenomenology not too large, decreasing.
Funding of Ph.D.’s and Postdocs
• University funding: under pressure
• Present: 3 FOM-TH programs: Universities (<2007), NIKHEF
(<2007), Strings (<2009): also under pressure
• Very important: new FOM-TH proposal, in preparation.
Universities + NIKHEF
• Increasingly look toward European funding
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