add class in body tag in particular page in drupal 7

/var/www/html/gfd/sites/all/themes/globalfd/template.php

function globalfd_preprocess_html(&$vars) {
  $path = drupal_get_path_alias();
  $aliases = explode('/', $path);

  if ($aliases[1] == "arc-program" || $aliases[1] == "financial-calculators" || $aliases[1] == "articles" || $aliases[1] == "newsletters") {
  $vars['classes_array'][] = drupal_clean_css_identifier("auth-page");
  }
   
}