Assembly comprising a container with a threaded neck and a cap mounted on the neck to close the container, the neck of the container having a longitudinal axis (X-X') and comprising: - an opening; - at least two helical threads formed on an outer face of the neck; - a collar; and - an annular groove disposed between the helical threads and the collar; the cap comprising: - a cylindrical cap body centered on the longitudinal axis (X-X') and comprising at least two helical ribs designed to engage with the helical threads of the collar, the cap body being pivotally mounted, about a pivot axis transverse to the longitudinal axis (X-X'), between a closed position in which the cap body closes the neck opening and an open position in which the neck opening is released to allow access to the interior of the container; - a tamper-evident ring centered on the longitudinal axis (X-X'); - frangible bridges connecting the cap body to the tamper-evident ring and designed to break definitively on first opening; and - two connecting arms connected on the one hand to the tamper-evident ring and on the other hand to the cap body via a hinge; wherein the tamper-evident ring comprises: - a fastening collar; - elastically deformable spring-loaded axial positioning tabs; and - at least two resiliently deformable centering tabs, each of the centering tabs having a length greater than the length of each of the axial positioning tabs; - when the cap is mounted on the container neck: - the axial positioning tabs are engaged in the annular groove of the neck; - the centering tabs rest on the external face of the neck so as to generate a force opposing the rotation of the tamper-evident ring about the longitudinal axis (X-X'). the neck of the container having a longitudinal axis (X-X') and comprising: - an opening; - at least two helical threads formed on an outer face of the neck; - a collar; and - an annular groove disposed between the helical threads and the collar; - at least two helical threads formed on an outer face of the neck; - a collar; and - an annular groove disposed between the helical threads and the collar; the cap comprising: - a cylindrical cap body centered on the longitudinal axis (X-X') and comprising at least two helical ribs designed to engage with the helical threads of the collar, the cap body being pivotally mounted, about a pivot axis transverse to the longitudinal axis (X-X'), between a closed position in which the cap body closes the neck opening and an open position in which the neck opening is released to allow access to the interior of the container; - a tamper-evident ring centered on the longitudinal axis (X-X'); - frangible bridges connecting the cap body to the tamper-evident ring and designed to break definitively on first opening; and - two connecting arms connected on the one hand to the tamper-evident ring and on the other hand to the cap body via a hinge; - a cylindrical cap body centered on the longitudinal axis (X-X') and comprising at least two helical ribs designed to engage with the helical threads of the collar, the cap body being pivotally mounted, about a pivot axis transverse to the longitudinal axis (X-X'), between a closed position in which the cap body closes the neck opening and an open position in which the neck opening is released to allow access to the interior of the container; - a tamper-evident ring centered on the longitudinal axis (X-X'); - frangible bridges connecting the cap body to the tamper-evident ring and designed to break definitively on first opening; and - two connecting arms connected on the one hand to the tamper-evident ring and on the other hand to the cap body via a hinge; wherein the tamper-evident ring comprises: - a fastening collar; - elastically deformable spring-loaded axial positioning tabs; and - at least two resiliently deformable centering tabs, each of the centering tabs having a length greater than the length of each of the axial positioning tabs; - when the cap is mounted on the container neck: - the axial positioning tabs are engaged in the annular groove of the neck; - the centering tabs rest on the external face of the neck so as to generate a force opposing the rotation of the tamper-evident ring about the longitudinal axis (X-X'). - a fastening collar; - elastically deformable spring-loaded axial positioning tabs; and - at least two resiliently deformable centering tabs, each of the centering tabs having a length greater than the length of each of the axial positioning tabs; - when the cap is mounted on the container neck: - the axial positioning tabs are engaged in the annular groove of the neck; - the centering tabs rest on the external face of the neck so as to generate a force opposing the rotation of the tamper-evident ring about the longitudinal axis (X-X'). - the axial positioning tabs are engaged in the annular groove of the neck; - the centering tabs rest on the external face of the neck so as to generate a force opposing the rotation of the tamper-evident ring about the longitudinal axis (X-X').