Wordpress Query by category slug

home.php

<?php

$args = array(
    'category_name'    => 'slider'
);
$loop = new WP_Query( $args ); 
if ( $loop->have_posts() ) : ?>

    <div id="vgslider" class="vg__slider-wrap owl-carousel owl-theme">

        <?php while ( $loop->have_posts() ) : $loop->the_post(); ?>
            <?php if(has_post_thumbnail()) :?>
            <div class="vg__slider vg__slider--1" style="background-image:url('<?php the_post_thumbnail_url( 'full' ); ?>')">
              <?php if( rwmb_meta( 'vg_url' ) ) :?>
                <a href="<?php echo rwmb_meta( 'vg_url' ); ?>" class="vg__slider__more-btn">
                  <?php echo rwmb_meta( 'vg_readmore' ); ?>
                </a>
              <?php endif; ?>
            </div>
            <?php else :?>

            <?php endif;?>

      <?php endwhile; ?>
    </div><!-- #video-sidebar-right -->


<?php endif; ?>