Ajax Parameter an PHP übergeben

$(document).ready(function(){

  $.ajax({
    type: "POST",
    data: {
      class: 'TicketRepository',
      method: 'ladeChartVerlaufOffen4',
      fb: document.getElementsByClassName('auswahlfachbereich')[0].value --> dieser Parameter soll in der Abfrage ankommen
    },
    url: "../../src/ticket/HandlerChartVerlaufOffen4.php",
    dataType: "json",
    success: function(data) {

      var x = [];
      var y = [];
      var z = [];

      for(var i in data) {
        x.push(data[i].tag);
        y.push(data[i].anzahl);

        z.push(parseInt(data[i].anzahl));

      }
      const s = (z.reduce((prev, curr) => prev + curr, 0))/z.length;
      const sum = s.toFixed(0);

      var chartdata = {
        labels: x,
        datasets : [
          {
            label: 'Durchschnitt letzte 30 Tage ' + '(' + sum + ')',
            backgroundColor: '#ed9a56',
            borderColor: 'rgba(200, 200, 200, 0.75)',
            hoverBackgroundColor: '#4d82b8',
            hoverBorderColor: 'rgba(200, 200, 200, 1)',
            data: y
          }
        ]
      };

      var ctx = $("#chartVerlaufOffen4");

      var barGraph = new Chart(ctx, {
        type: 'bar',
        data: chartdata,
        options: {
          scales: {
            yAxes: [{
              ticks: {
                beginAtZero: true
              }
            }]
          }
        }
      });

    },
    error: function(data) {
      console.log(data);
    }
  });
});

<?php
namespace App\Ticket;

require_once 'TicketRepository.php';
require_once 'ModelChartVerlaufOffen4.php';
use PDO;

if(isset( $_POST['class']) && isset( $_POST['method'])) {
     $myTicketRepository = new TicketRepository($pdo = new PDO('mysql:dbname=db; host=1234', 'a', 'in'));
     $result = $myTicketRepository->ladeChartVerlaufOffen4();
     echo json_encode($result);
}

$pdo = null;
?>

function ladeChartVerlaufOffen4()
    {
      $statement = $this->pdo->prepare("SELECT *
        FROM (SELECT id_offen_gruppen AS ids, DATE_FORMAT(o.datum, '%d.%m') AS tag, SUM(o.anzahl) AS anzahl
          FROM crmdb_copy.offen_gruppen o
          WHERE o.status IN(?, ?)
          AND YEAR(o.datum) =?
          AND o.gruppen =? --> hier soll dr Parameter ankommen
          GROUP BY DATE_FORMAT(o.datum, '%d.%m')
          ORDER BY o.datum DESC LIMIT 30) sub
        ORDER BY ids");

      $statement->execute(array(0, 1, date('Y')));

      $statement->setFetchMode(PDO::FETCH_CLASS, "App\\Ticket\\ModelChartVerlaufOffen4");

      $data = $statement->fetchAll(PDO::FETCH_CLASS, "App\\Ticket\\ModelChartVerlaufOffen4");

      return $data;
    }