There is no syntactic counterpart to the
in Japanese. Among world's languages, there are languages that do have articles and languages that do not. English and Japanese belong to the former and the latter respectively. This is a fundamental difference, and you just cannot map an article from one language to another language that does not have it.
Since this website is biased towards programmers, to give a close counterpart to the two types of natural languages in programming languages, natural languages with articles like English correspond to class-based object oriented programming languages like C++, Java, Ruby. Natural languages without articles like Japanese correspond to prototype-based object oriented programming languages like Javascript. And as you may be able to guess, articles in natural languages correspond to constructors in programming languages.
But it you want to express a similar nuance using different syntactic components, then you can use expressions like その
, 唯一の
, 先ほどの
, 例の
, 問題の
,問題になっている
, 話題になっている
depending on the context.
The
is not a particle. It is a definite article. I don't get what you mean by "emphasize a topic the same way you do with 'The' in English". Probably you mean "mark the definiteness", or "mark the focus" withthe
?