The time for which a Klong lives, light would travel 15.3 meters in that time, and in the time a Kshort is alive, light would travel only 2.7 centi meters. Kshort and Klong are the same particle only different in how long they live.
(they are like the same sprinter with different speed capacities)

A meson is a very small particle that always consists of two quarks

(since quarks are very popular I believe I don’t have to explain that now)

WE know 100s of different mesons to exist in nature, one of them is the so called K meson.

(its also ca…lled a strange meson because there is a strange quark inside such a meson)

SO the K meson (and its anti particle K bar meson) occur in nature in two different kind, Kshort and Klong

(This is NOT true for any other particle we know)

Thats what I described above the Klong meson and the Kshort meson are named so because the Kshort lives for very short time 90 pico seconds and the Klong meson lives for long time 512 pico seconds. pico second is 1000th of 1 billionth of a second. In that small time, light which travels the fastest would cover 2.7 centi meters in Kshort life tme and 15.3 meters for Klong life time.

And I have studied these two mesons very extensively so I am very fond of them, I believe my kids will go by that name…

(And if the joke is not over) …. Kshort Kshort you gotta be careful, don’t spill the milk. And Klong You gotta go over to the Walmart and get me some glue. Kshort says papa Klong cant go to the walmart cos the walmart is 1 mile away and he can only go up-to 15 meters at most. Papa says OK Iwll take care of the eeraands