Energy Evolution for the SiversAsymmetries in Hard Processes
Peng Sun
LBNL in collaboration with F YuanarXiv: 1304.5037
Outlines TMD factorization Energy evolution Fit the sivers function with SIDIS
experiments Implement the TMD evolution from low Q
SIDIS to Drell-Yan Collins asymmetries
23/4/21 2
TMD factorization TMD factorization is an extension and
simplification to the collinear factorization
Simplifies the kinematicsPower counting, correction 1/Q neglected
(PT,Q)=H(Q) f1(x1,k1T,Q) f2(x2,k2T, Q) S(T)There is no x- and kT-dependence in the hard
factor
23/4/21 3
Energy evolution
At the leading order of ɑs
By solving CSS evolution equations
There is no Landau pole singularity in the integral
Almost parameter-freeNo Q-dependent non-perturbative form factorGaussian assumption at lower scale Q0
23/4/21 6
SIDIS
SIDIS at HERMES
g0=0.1, gh=0.045
Q2=3.14GeV2, x=0.16
23/4/21 7
Q2=3.14GeV2
X=0.16
SIDIS at COMPASS, Q2=7.75, x=0.1
Drell-Yan
23/4/21 9
Fit to Sivers asymmetries
With the evolution effects taken into account. Not so large Q difference
23/4/21 10
Uncertainties in the Sivers functions: moments
23/4/21 14
Up quark most constrained in the moderate xLarge uncertainties in small-x region and sea quark
Predictions at RHIC
About a factor of 2 reduction, as compared to previous order of magnitude difference
23/4/21 15
Collins asymmetries in e+e- →hh
The collins effect is porprotianal to cos(2ɸ0)
Collins asymmetries
Ec.m.≈10GeV, di-hadron azimuthal asymmetric correlation in e+e- annihilation
23/4/21 17
Test the evolution at BEPC
Ec.m.=4.6GeV, di-hadron in e+e- annihilation BEPC-(Beijing electron-positron collider)
23/4/21 18
Conclusion We evaluate the energy dependence for
Sivers asymmetries in hard processes, from HERMES/COMPASS to typical Drell-Yan process
The same evolution procedure consistently describes the Collins asymmetries from HERMES/COMPASS and BELLE
Further tests are needed to nail down this issue
23/4/21 19
Thank you very much!
Ji Ma Yuan scheme, in SIDIS
Structure function is
It depends on ρ
Collins scheme
This version is much simpler than that of Ji Ma Yuan
In Aybat-Collins-Qiu-Rogers framework
And then
Here gK(b) is gc×b2
Energy Evolution in TMD factorization scheme
Aybat-Collins-Qiu-Rogers, 2011
Q2-dependence Aybat-Prokudin-Rogers, 2011
23/4/21 25Needs a cross check!
Collins asymmetries in SIDIS
asd
23/4/21 26
Energy evolution
In our framework
At the leading order of ɑs