The Structure and Dynamics Nora Brambilla (U. Milano) of Hadron Systems with two Heavy Quarks.
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Transcript of The Structure and Dynamics Nora Brambilla (U. Milano) of Hadron Systems with two Heavy Quarks.
The Structure and Dynamics
Nora Brambilla (U. Milano)
of Hadron Systems
with two Heavy Quarks
QCD and the Hadrons
Parameters:
,
QCD and the Hadrons Structure
QCD and the Hadrons Dynamics
Bali et al. 95
Systems made by two quarks are golden systems for strong interactions
Precision determinations of QCD parameters (of interest for SM and BSM physics)
information on QCD vacuum and low energy properties (of interest for theories beyond QCD)
information on the transition region from high energy to low energy (of interest for the behaviour of perturbative series)
They can provide us with:
how is this?
Low energy (nonperturbative) factorizedeffects depend on the size of the physical
system
Plan of the talk
•Introduction•small systems,condensates,resummations and precise determinations •gluelumps, hybrids and condensates•inclusive decays, octets and factorization•Big systems,nonperturbative potentials and qcd vacuum models•“QQ” systems in baryons•challenges
With the November 1974 revolution also the traditional quarkonium spectroscopy started:•huge impact: c quark discovery; asymptotic freedom; confinement.
•few conventional charmonium states;•limited production mechanisms;•limited statistics;•potential model.
Quarkonium at the beginning
Progress based on
New data
New Theory
quark pair creation relevant only for light quarks and at large
distances one channel is dominant
(perturbative scale!)
QQ: a multiscale System
and
Multiscale Non-relativistic bound states
No correlation between the number of gluons and the importance of the amplitude due to multiple
scales; gauge dependence.In the Bethe-Salpeter approach great difficulties
Nonrelativistic EFTs
•Systematic expansion;•Model independent; Gauge invariant;•Factorization between high and low energy;•Only the relevant degrees of freedom remain dynamical (the rest integrated out in a controlled way);•All the relevant Fock components appear and with a power counting in v (e.g. octets)•Symmetries of the original theory constrain the c • Additional Symmetries of the system become manifest;•At the scale m the matching coeff. can be calculated in perturbation theory•Large logs can be resummed via RG.
Disentangling scales with EFTs
Hard
Soft(relative
momentum)
Ultrasoft (binding energy)
In QCD another scale is relevant
EFTs for Quarkonium
Poincare invariance of the EFT
Constraints from Poincare Invariance
Brambilla, Gromes, Vairo 03
In the same wayone gets relationsamong the matching potentials V
Small systems: QQ energies at
• Summing large beta0 (removing the renormalon of the series) Beneke et al., Hoang et al.,Brambilla et al, Pineda
• Summing the logs: RG correlated scales Luke and Savage; Manohar and Stewart; Pineda Soto
The bottleneck are nonperturbative contributions: but they are suppressed --->
precision calculations are possible
perturbative singlet potential
singlet singletoctet
low energy gluon
Dealing with the QCD perturbative series:
--Precise determinations of m_b and m_c
--High order calculations of the static singlet QQbar potential (four loops NLL):
full agreement with lattice
--
The Gluelump Spectrum
QQ Static spectrum with gluons
Juge Kuti Mornigstar 98-06
hybrid
Lattice
Gluelumps and hybrids in pNRQCD
lattice
Juge Kuti Morningstar 00 03
Brambilla Pineda Soto Vairo 00
for small r pNRQCD applies
Gluelumps and hybrids in pNRQCD:more symmetry!
lattice
Juge Kuti Morningstar 00 03
Brambilla Pineda Soto Vairo 00
Gluelumps Masses
Magnetic gluelump mass
Electric gluelump mass
is the fundamental object in many models of QCD vacuumStochastic Vacuum Model, Dosch et alDual QCD Baker et alBrambilla et al 97, 98,00
Gluelumps Masses
Magnetic gluelump mass
Electric gluelump mass
it gives also the leading nonperturbative correction to spectra and decay
It needs better lattice calculation!
Gluelumps Masses
Inclusive decays
Inclusive decays: perturbation and singlet model
Inclusive decays: NRQCD
Fock state content of QQbar in NRQCD:
Inclusive
decays
pNRQCDfactorization
nonperturbativeeffects in
condensates
large systems
Brambilla Pineda Soto Vairo 00
•A potential (quark model like) description emerges from the EFT
•V soft may be calculated on the lattice or in QCD vacuum modelsCreutz et al 82, Campostrini 85, Michael 85, Born et al 94, Bali et al 97k, Koma, Koma Wittig 2006, Brambilla et al 90 93 95 97, Dosch, Simonov:
Baker et al
Big systems: strongly coupled pNRQCD
The QCD potential
contains a hard and a soft part (in terms of Wilson loops)
Investigating the QCD vacuum
A QCD vacuum model is an assumption on the low energy behaviour of the Wilson loop
(gauge invariant, all the rest follows)
All QQ dynamics is given in terms of Wilson loops and electric and magnetic insertion in
the Wilson loop
Studies of Confinement on Wilson loops/V_0
Bali et al
Boryakov et al. 04
QCD Spin dependent potentials
-factorization; power counting; QM divergences absorbed by NRQCD matching coefficients
Spin dependent potentials
Such data can distinguish different models for the dynamics of low energy QCD
Exact relations on the V’s from Poincare
e. g.
It is a check of the lattice calculation
Koma and Koma 2006
Gromes relation
many other such relations in pNRQCD, Brambilla et al. 2003
QCD Spin independent potentials
QQq and QQQ baryons
Doubly Charmed Baryons
Selex 02,04,06 but no confirmation by Focus and babar
QQq systems
Notice that
diquark approximation not valid
Hyperfine separation
Selex data,Fig. from T. Cohen et al.
pNRQCD result
Lattice
See the internal QQ excitations ?
state 3780 l>0?problems with e.m.
transitions
QQQ states
The lowest QQQ states
are few hundreds
Mevs lower than
Bjiorken’sY. Jia 06
Goodtestingbed for
QCD vacuummodels
OPEN CHALLENGES
Quarkonium Production at Tevatron and LHC
Polarization at tevatronCFD 06
The polarization problem
A solution may come froman EFT with different power counting
•Most of the new states are close to threshold• It is most important to construct and EFT close to
threshold (talk Weise)
Quarkonium at finite T & Heavy Ion collisions
Spectral density above and below Tc
QQbar singlet Free energy at
finite T
EFT approach
for the scale T, gT, g^2 T
•Direct formulation on the lattice:pNRQCD on the lattice
• Quarkonium Van Der Waals Interaction and Quarkonium on nuclei
Search for Physics BSM
Dark matter: run at Belle at Y(3S)
Light Higgs in eta_b search: breakdown of lepton universality in Y decays
LFV processes and CPV processes in J/psi decays at BESIII
OutlookEffective field theories provide a systematic tool to investigate a wide range of heavy quark observables inside QCD
They need to be complemented by lattice calculations
These theory tools can match some of the intense experimental progress of the last few years and of the near future, but more has to be done:
Heavy quark bound states are a unique lab for the study of the strong interactions from the high energy scales where precision studies can be made to the low energy region: use all the present and future data to test/develop our theory tools on the way to the hadron structure and dynamics
Some Perturbative calculations at higher orderLattice calculations of condensates/wilson loopsModels for the QCD vacuumNew EFTs close to threshold