To elucidate further, \( 1, 2, 3, 4 ) is just short for ( \1, \2, \3, \4 ):

$ perl -le'
    use Data::Dumper;
    @x = \( 4, 5, 6, 7 );
    print Dumper \@x;
'
$VAR1 = [
          \4,
          \5,
          \6,
          \7
        ];

$ perl -le'
    use Data::Dumper;
    @x = ( \4, \5, \6, \7 );
    print Dumper \@x;
'
$VAR1 = [
          \4,
          \5,
          \6,
          \7
        ];
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And the assignment to a scalar does the same thing with or without the backslash(es):

$ perl -le'
    use Data::Dumper;
    $x = ( 4, 5, 6, 7 );
    print Dumper $x;
'
$VAR1 = 7;

$ perl -le'
    use Data::Dumper;
    $x = \( 4, 5, 6, 7 );
    print Dumper $x;
'
$VAR1 = \7;

$ perl -le'
    use Data::Dumper;
    $x = ( \4, \5, \6, \7 );
    print Dumper $x;
'
$VAR1 = \7;
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