Light-front densities for transversely polarized hadrons Lorcé Cédric Mainz University Germany *4th Workshop on ERHMT, JLAb, Newport News, Virginia USA (May 18-21, 2010) *
Dec 25, 2015
Light-front densities for transversely
polarized hadrons Lorcé CédricMainz UniversityGermany
*4th Workshop on ERHMT, JLAb, Newport News, Virginia USA (May 18-21, 2010)
*
Standard PictureBreit frame
BUT Lorentz contraction
Creation/annihilation of pairsNO probability/charge
density interpretation
[Ernst, Sachs, Wali (1960)][Sachs (1962)]
Correct Picture
Extreme Lorentz contraction 2D picture
No creation/annihilation of massive pairs
Light-front frame
[Burkardt (2001,2003)]
Transverse Charge Densities
p
n
Long. pol. Transv. pol.
Electric dipole!
[Miller (2007)] [Carlson & Vdh (2008)]
Bint
Transverse Charge Densities
Monopole Anomalous!
Interpretation:
Transversity basis
S
d
Induced EDM
Dipole
u
d
X
dipole
Similarly for higher spins
quadrupolemonopole octupole
2j+1 circular multipoles!
= + + +
Transverse Charge Densities
[Lorcé (2009)]
[Alexandrou et al.
(2008,2009)]
Distortions of transverse charge densities due to anomalous values of
EM moments
Claim:
Higher Spins 2j+1 circular multipoles!
[Lorcé (2009)]
ChargeChargenormalizationnormalization
UniversalUniversalg=2 factorg=2 factor
Dirac
EWSMSM
SupergravitySupergravity
Generalized Polarizabilities
VCS in low limit described by 6 GPs
Linear response to external quasi-static dipole electric
field
Generalized Polarizabilities[Gorchtein, Lorcé, Pasquini, Vdh
(2010)]dipole
quadrupole
monopole
Only 3 linear combinations available!
E E E
GTMDs (Generalized Transverse Momentum dependent parton
Distributions)
Complete parametrization
[Meißner, Metz, Schlegel (2009)]
Probabilistic interpretation in impact-parameter space with
dd
,
GCDs (Generalized transverse Charge Densities)
[Lorcé, Pasquini (in preparation)]
k T
b
Unpolarized u quark in unpolarized proton
k T fixed
GCDs (Generalized transverse Charge Densities)
[Lorcé, Pasquini (in preparation)]
k T
Unpolarized u quark in unpolarized proton
k T fixed
= +
GCDs (Generalized transverse Charge Densities)
[Lorcé, Pasquini (in preparation)]
,k T fixed
k T
k T
k T
k T
Unpolarized u quark in unpolarized proton
GCDs (Generalized transverse Charge Densities)
[Lorcé, Pasquini (in preparation)]
Unpolarized u and d quarks in unpolarized
proton
u
d
More u than d in central region!
FFs Correct picture on the light front Distortions of densities due to anomalous moments « Natural » EM moments form a pseudo-Pascal triangle
GPs VCS amplitude in the light front 3 out of 6 mapped out
GTMDs & Co. Full information Anisotropic distribution of u/d quarks dominance in central region of proton/neutron
Summary
k T