A bstract Results are presented from a search for chargedlepton flavor violating (CLFV) interactions in top quark production and decay in pp collisions at a centerofmass energy of 13 TeV. The events are required to contain one oppositely charged electronmuon pair in the final state, along with at least one jet identified as originating from a bottom quark. The data correspond to an integrated luminosity of 138 fb − 1 , collected by the CMS experiment at the LHC. This analysis includes both the production (q → e μ t) and decay (t → e μ q) modes of the top quark through CLFV interactions, with q referring to a u or c quark. These interactions are parametrized using an effective field theory approach. With no significant excess over the standard model expectation, the results are interpreted in terms of vector, scalar, and tensorlike CLFV fourfermion effective interactions. Finally, observed exclusion limits are set at 95% confidence levels on the respective branching fractions of a top quark to an e μ pair and an up (charm) quark of 0 . 13 × 10 − 6 (1 . 31 × 10 − 6 ), 0 . 07 × 10 − 6more »
Isovector and flavor diagonal charges of the nucleon from 2+1+1 flavor QCD
We present highstatistics 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
chiralcontinuum 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, $g_A^{ud}
= 1.218(25)(30)$, $g_S^{ud} = 1.022(80)(60) $ and $g_T^{ud} =
0.989(32)(10)$, are used to obtain lowenergy 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 more »
 Award ID(s):
 1653405
 Publication Date:
 NSFPAR ID:
 10097109
 Journal Name:
 The 36th Annual International Symposium on Lattice Field Theory (LATTICE2018)
 Volume:
 334
 Page Range or eLocationID:
 131
 Sponsoring Org:
 National Science Foundation
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