nginxを起動後ブラウザ上で403 forbidden

php
http {
  server {      
    listen      8001 default;
    server_name  localhost;
    root /var/www/ruby;

    location /var/www/ruby {
      autoindex on;
      if (!-e $request_filename) {
        rewrite ^/(.+)#  /index.php?q=$1 last;
        break;
      }
    }
    location ~ \.php$ {
      fastcgi_pass 127.0.0.1:9000;
      fastcgi_param SCRIPT_FILENAME /var/www/wordpress$fastcgi_script_name;
      fastcgi_param PATH_INFO $fastcgi_script_name;
      include fastcgi_params;
    }
  }


  include       /etc/nginx/mime.types;
  default_type  application/octet-stream;

  log_format  main  '$remote_addr - $remote_user [$time_local] "$request" '
    '$status $body_bytes_sent "$http_referer" '
    '"$http_user_agent" "$http_x_forwarded_for"';
  access_log  /var/log/nginx/access.log  main;
  sendfile        on;
#tcp_nopush     on;  
  keepalive_timeout  65;

#gzip  on;
}

上記nginx.confです。（便宜上PHPとしています。）rootのディレクトリのパーミッションは755になっているのですが、ブラウザ上で403 Forbidden
nginx/1.8.0と表示されてしまいます。

パーミッション以外の設定を見直す必要があるのでしょうか？

追記：
回答ありがとうございます。

下記confでも同一状態になるので、locationディレクティブが原因ではないようです。

PHP
user  nginx;
worker_processes  1;  

error_log  /var/log/nginx/error.log warn;
pid        /var/run/nginx.pid;


events {
  worker_connections  1024;
}


http {
  server {
    listen      8001;
    server_name  localhost;
    root /var/www/ruby;
  }


  include       /etc/nginx/mime.types;
  default_type  application/octet-stream;

  log_format  main  '$remote_addr - $remote_user [$time_local] "$request" '
    '$status $body_bytes_sent "$http_referer" '
    '"$http_user_agent" "$http_x_forwarded_for"';
  access_log  /var/log/nginx/access.log  main;
  sendfile        on;
#tcp_nopush     on; 
  keepalive_timeout  65; 

#gzip  on; 
}

/var/log/nginx/error.log ↓

PHP
2015/12/09 19:36:12 [error] 9643#0: *1 directory index of "/var/www/ruby/" is forbidden, client: 127.0.0.1, server: localhost, request: "GET / HTTP/1.1", host: "localhost:8001"