{
  "id": "2209.02476",
  "version": "v1",
  "published": "2022-09-06T13:19:25.000Z",
  "updated": "2022-09-06T13:19:25.000Z",
  "title": "Enhancement of Direct $CP$ asymmetry in $Z'$ models",
  "authors": [
    "Shireen Niteen Gangal"
  ],
  "categories": [
    "hep-ph"
  ],
  "abstract": "We consider $CP$-violating $Z'$ models to account for the anomalies in $b \\to s \\ell \\ell$ decays. Using the updated constraints from lepton flavor universality (LFU) violating ratios, $b \\to s \\mu \\mu $ $CP$-conserving and $CP$-violating observables, $B_s-\\bar{B}_s$ mixing and neutrino trident we obtain the favored parameter space of two classes of $Z'$ models generating the `1D' new physics scenarios with $C_9^{\\rm NP} <0$ and $C_9^{\\rm NP} = -C_{10}^{\\rm NP}$. We show that the predictions of direct $CP$ asymmetry $A_{CP}$ in $B^+ \\to K^+ \\mu \\, \\mu$ decays close to the $c \\bar{c}$ resonance region can be used to detect the presence of new $CP$ violating phases in the $Z'$ couplings.The favored $1\\,\\sigma$ parameter space of $Z'$ models generating the scenario $C_9^{\\rm NP} <0$ allows for an enhancement in the integrated $A_{CP}$ in $q^2 =[8,9]\\,\\rm{GeV^2}$ bin up to $\\pm 10\\%$ and in the $q^2 =[6,7]\\,\\rm{GeV^2}$ bin up to $\\pm 5\\%$. We find that for a negative value of the phase of $J/\\psi$ resonance, although such an enhancement is possible in $Z'$ models generating the scenario $C_9^{\\rm NP} = -C_{10}^{\\rm NP}$, the favored parameter space prefers only positive values of $A_{CP}$. Hence, a future measurement of direct $CP$ asymmetry in these bins can potentially constrain the size of new $CP$ violating phases, and help in distinguishing between the two classes of $Z'$ models.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2022-09-06T13:19:25.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "enhancement",
      "models generating",
      "lepton flavor universality",
      "violating phases",
      "favored parameter space prefers"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 0,
      "language": "en",
      "license": "arXiv",
      "status": "editable"
    }
  }
}