Energy Evolution for the Sivers Asymmetries in Hard Processes
description
Transcript of Energy Evolution for the Sivers Asymmetries in Hard Processes
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