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SUMMARY:[RIKEN Seminar] Sparse modeling approach to obtaining the shear vi
scosity from smeared correlation functions
DTSTART;VALUE=DATE-TIME:20200514T130000Z
DTEND;VALUE=DATE-TIME:20200514T150000Z
DTSTAMP;VALUE=DATE-TIME:20220528T234143Z
UID:indico-event-8421@indico.bnl.gov
DESCRIPTION:We propose the sparse modeling method to estimate the spectral
\nfunction from the smeared correlation functions.\nWe give a description
of how to obtain the shear viscosity from the\ncorrelation function of the
renormalized\nenergy-momentum tensor (EMT) measured by the gradient flow
method\n($C(t\,\\tau)$) for the quenched QCD at finite temperature.\nThe
measurement of the renormalized EMT in the gradient flow method\nreduces
a statistical uncertainty\nthanks to its property of the smearing.\nHoweve
r\, the smearing breaks the sum rule of the spectral function and\nthe ove
r-smeared data in the correlation function\nmay have to be eliminated from
the analyzing process of physical observables.\nIn this work\, we demonst
rate that the sparse modeling analysis in the\nintermediate-representation
basis (IR basis)\,\nwhich connects between the Matsubara frequency data a
nd real frequency data.\nIt works well even using very limited data of $
C(t\,\\tau)$ only in the\nfiducial window of the gradient flow.\nWe utiliz
e the ADMM algorithm which is useful to solve the LASSO\nproblem under som
e constraints.\nWe show that the obtained spectral function reproduces the
input\nsmeared correlation function at finite flow-time.\nSeveral systema
tic and statistical errors and the flow-time dependence\nare also discusse
d.\n\nhttps://indico.bnl.gov/event/8421/
LOCATION:
URL:https://indico.bnl.gov/event/8421/
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