People who are not part of project should be able to see the ticket and get notified when added

[UDAY BONTHALA]

a.       People who are not part of project should be able to see the ticket  and get notified when added as watchers but should not be able to modify.

[Nic Brough -Adaptavist-]

Yes, you can do this, just let these users browse watch issues, and give them no other roles in the project.

[UDAY BONTHALA]

can you please explain detial

[Nic Brough -Adaptavist-]

Add a new role (unless you already have one for this).  Call it something like "read only"

Change the permission scheme so that it includes "browse project: role (read-only)"  Do NOT give the role any other rights.

Put the relevant people into the role in that project.