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Register a new userAddendum to arXiv:0907.2110: Charm and Bottom Quark Masses: An Update
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We update the experimental moments for the charm quark as computed in arXiv:hep-ph/0702103. and used in arXiv:0907.2110 and arXiv:1010.6157 for the determination of the charm-quark mass. The new value for the MSbar charm-quark mass reads mc(3GeV)=0.993+/-0.008 GeV.
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Lattice determinations of quark mass have made significant progress in the last few years. I will review recent advances in calculations of charm and bottom mass, which are near to achieving percent-level precision and with fully controlled systematics. Precise knowledge of these parameters is of particular interest for precision Higgs studies at future accelerators.
We calculate the up-, down-, strange-, charm-, and bottom-quark masses using the MILC highly improved staggered-quark ensembles with four flavors of dynamical quarks. We use ensembles at six lattice spacings ranging from $aapprox0.15$~fm to $0.03$~fm and with both physical and unphysical values of the two light and the strange sea-quark masses. We use a new method based on heavy-quark effective theory (HQET) to extract quark masses from heavy-light pseudoscalar meson masses. Combining our analysis with our separate determination of ratios of light-quark masses we present masses of the up, down, strange, charm, and bottom quarks. Our results for the $overline{text{MS}}$-renormalized masses are $m_u(2~text{GeV}) = 2.130(41)$~MeV, $m_d(2~text{GeV}) = 4.675(56)$~MeV, $m_s(2~text{GeV}) = 92.47(69)$~MeV, $m_c(3~text{GeV}) = 983.7(5.6)$~MeV, and $m_c(m_c) = 1273(10)$~MeV, with four active flavors; and $m_b(m_b) = 4195(14)$~MeV with five active flavors. We also obtain ratios of quark masses $m_c/m_s = 11.783(25)$, $m_b/m_s = 53.94(12)$, and $m_b/m_c = 4.578(8)$. The result for $m_c$ matches the precision of the most precise calculation to date, and the other masses and all quoted ratios are the most precise to date. Moreover, these results are the first with a perturbative accuracy of $alpha_s^4$. As byproducts of our method, we obtain the matrix elements of HQET operators with dimension 4 and 5: $overline{Lambda}_text{MRS}=555(31)$~MeV in the minimal renormalon-subtracted (MRS) scheme, $mu_pi^2 = 0.05(22)~text{GeV}^2$, and $mu_G^2(m_b)=0.38(2)~text{GeV}^2$. The MRS scheme [Phys. Rev. D97, 034503 (2018), arXiv:1712.04983 [hep-ph]] is the key new aspect of our method.
We calculate the decay width of $h^0 to b bar{b}$ in the Minimal Supersymmetric Standard Model (MSSM) with quark-flavour violation (QFV) at full one-loop level. The effect of $tilde{c}-tilde{t}$ mixing and $tilde{s}-tilde{b}$ mixing is studied taking into account the constraints from the B-meson data. We discuss and compare in detail the decays $h^0 to c bar{c}$ and $h^0 to b bar{b}$ within the framework of the perturbative mass insertion technique using the Flavour Expansion Theorem. The deviation of both decay widths from the Standard Model results can be quite large. While in $h^0 to c bar{c}$ it is almost entirely due to the flavour violating part of the MSSM, in $h^0 to b bar{b}$ it is mainly due to the flavour conserving part. Nevertheless, $Gamma(h^0 to b bar{b})$ can fluctuate up to $sim 7%$ due to QFV chargino exchange with large $tilde{c}-tilde{t}$ mixing. due to QFV chargino exchange with large $tilde{c}-tilde{t}$ mixing.
This work summarizes the current status of the measured semileptonic branching fractions $B^{0,+} to X_c mu u$. The sum of exclusive measurements is compared with the inclusive determination, accounting for isospin extrapolation. Further derived quantities are computed, taking into account different explanations for the unmeasured components of the total branching fraction. These quantities focus on the charge breakdown of the final states, and are designed for use as inputs or comparisons in future experimental measurements.
We investigate heavy quark symmetries for heavy light meson-antimeson systems in a contact-range effective field theory. In the SU(3) light flavor limit, the leading order Lagrangian respecting heavy quark spin symmetry contains four independent counter-terms. Neglecting $1/m_Q$ corrections, three of these low energy constants can be determ1ined by theorizing a molecular description of the $X(3872)$ and $Z_b(10610)$ states. Thus, we can predict new hadronic molecules, in particular the isovector charmonium partners of the $Z_b(10610)$ and the $Z_b(10650)$ states. We also discuss hadron molecules composed of a heavy meson and a doubly-heavy baryon, which would be related to the heavy meson-antimeson molecules thanks to the heavy antiquark-diquark symmetry. Finally, we also study the $X(3872) to D^0bar D^0pi^0$ decay, which is not only sensitive to the short distance part of the $X(3872)$ molecular wave function, as the $J/psipipi$ and $J/psi3pi$ $X(3872)$ decay modes are, but it is also affected by the long-distance structure of the resonance. Furthermore, this decay might provide some information on the interaction between the $Dbar D$ charm mesons.
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