PoS - Proceedings of Science
Volume 334 - The 36th Annual International Symposium on Lattice Field Theory (LATTICE2018) - Hadron Structure
Isovector and flavor diagonal charges of the nucleon from 2+1+1 flavor QCD
R. Gupta*, T. Bhattacharya, V. Cirigliano, B. Yoon, Y.C. Jang, H.W. Lin  on behalf of PNDME Collaboration
Full text: pdf
Published on: May 29, 2019
We present high-statistics results for the isovector and flavor diagonal charges of the proton using 11 ensembles of 2+1+1 flavor HISQ fermions. In the isospin symmetric limit, results for the neutron are given by the $u \leftrightarrow d$ interchange. A chiral-continuum fit with leading order corrections was made to extract the connected and disconnected contributions in the continuum limit and at $M_\pi=135$~MeV. All results are given in the $\overline{MS}$ scheme at 2~GeV. The isovector charges, $g_A^{u-d}
= 1.218(25)(30)$, $g_S^{u-d} = 1.022(80)(60) $ and $g_T^{u-d} =
0.989(32)(10)$, are used to obtain low-energy constraints on novel scalar and tensor interactions, $\epsilon_{S}$ and $\epsilon_{T}$, at the TeV scale. The flavor diagonal axial charges are: $g_A^u
\equiv \Delta u \equiv \langle 1 \rangle_{\Delta u^+} =
0.777(25)(30)$, $g_A^d \equiv \Delta d \equiv \langle 1
\rangle_{\Delta d^+} = -0.438(18)(30)$, and $g_A^s \equiv \Delta s
\equiv \langle 1 \rangle_{\Delta s^+} = -0.053(8)$. Their sum gives the total quark contribution to the proton spin, $\sum_{q=u,d,s}
(\frac{1}{2} \Delta q) = 0.143(31)(36)$. This result is in good agreement with the recent COMPASS analysis $0.13 < \frac{1}{2}
\Delta \Sigma < 0.18$. Implications of results for the flavor diagonal tensor charges, $g_T^u = 0.784(28)(10)$, $g_T^d =
-0.204(11)(10)$ and $g_T^s = -0.0027(16)$ for constraining the quark electric dipole moments and their contributions to the neutron electric dipole moment are discussed. These flavor diagonal charges also give the strength of the interaction of dark matter with nucleons via axial and tensor mediators.
DOI: https://doi.org/10.22323/1.334.0131
How to cite

Metadata are provided both in "article" format (very similar to INSPIRE) as this helps creating very compact bibliographies which can be beneficial to authors and readers, and in "proceeding" format which is more detailed and complete.

Open Access
Creative Commons LicenseCopyright owned by the author(s) under the term of the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.