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Volume 363 - 37th International Symposium on Lattice Field Theory (LATTICE2019) - Main session
Vector current renormalisation in momentum subtraction schemes using the HISQ action
D. Hatton,* C. Davies, P. Lepage, A. Lytle on behalf of HPQCD Collaboration
*corresponding author
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Pre-published on: 2019 December 05
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As the only lattice vector current that does not require renormalisation is the point-split conserved current it is convenient to have a robust, precise and computationally cheap methodology for the calculation of vector current renormalisation factors, $Z_V$. Momentum subtraction schemes, such as RI-SMOM, implemented nonperturbatively on the lattice provide such a method if it can be shown that the systematic errors, e.g. from condensates, are well controlled.

We present $Z_V$ calculations for the conserved current in both the RI-SMOM and RI$'$-MOM momentum subtraction schemes as well as local current renormalisation in the RI-SMOM scheme. By performing these calculations at various values of the momentum scale $\mu$ and different lattice spacings we can investigate the presence of power suppressed nonperturbative contributions and compare the results to expectations arising from the Ward-Takahashi identity. Our results show that the RI-SMOM scheme provides a well controlled determination of $Z_V$ but the standard RI$'$-MOM scheme does not.

We then present some preliminary uses of these $Z_V$ calculations in charm physics.
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