Smoking article with a mouth end cavity and ventilation

A smoking article comprising:

• a tobacco rod;
• and
• a filter connected to the tobacco rod, the filter comprising:
• a hollow mouth end portion;
• and
• a filtration portion upstream of the hollow mouth end portion, the filtration portion comprising one or more filter segments;
• wherein the hollow mouth end portion defines a cavity at the mouth end of the filter providing an unrestricted flow channel that extends from the downstream end of the filtration portion to the mouth end of the filter,
• wherein the length of the hollow mouth end portion is at least about 25 percent of the overall filter length and within about 5 mm of the length of the filtration portion and wherein the smoking article comprises a ventilation zone comprising at least one circumferential row of perforations provided at a location at least about 2 mm upstream from the downstream end of the filtration portion.