You found a crossroad of dog enlightenment.
You may ask yourself, what's up with the letter a showing up in a lot of my works, often accompanied by parenthesis and small crosses? These are actually mathematical entities called creation and annihilation operators.
Operators are matematical objects that act on some sort of vector producing a transformation that results in another vector from that same vector space. If an operator acts on a function, it'll return something that's also a function. If it acts on an usual 3-dimensional vector -- a R3 vector -- it'll return a vector of the same kind. On a matrix, it'll return another matrix. It so happens that in Quantum Mechanics we often represent a physical state through a type of vector and we may thus operate on it.
Let's say we have a physical state represented by the letter Φ. This physical state is being treated as a mathematical object. As a physical state evolves with time, the particles that make it up might interact and in doing so we may end with another state with another group of particles. To transform the initial state into the final one, we may operate on it with creation and annihilation operators. Simply put, these operators will act (mathematically) on the physical state and erase the initial particles and create the final ones, possibly with many other particles created and erased in between. Are particles destroyed and created when they interact or do they just transform into each another, these operators being nothing more than a mathematical abstraction of that process? The answer is that it doesn't matter. The math checks out, the model is useful.
While a(q) represents the operator that annihilates a particle q in a physical state it acts upon, a†(q) is the creation operator that creates the particle q. The fields of quantum field theory actually propagate said operators and thus we have creation and annihilation fields. We are led to ponder if creation and annihilation are simply the way through which the fundamental blocks of physical reality interact. As for the † symbol, called dagger, it represents a conjugate transpose, which basically means both operators are tied through a mathematical process that you can look up later.
Said symbol, however, is rendered like a cross in many typographic styles. Crosses are, of course, the always present symbol of Christian religion. Crosses, creation, annihilation. It's impossible not to be fascinated by these mathematical symbols. To use them in art is a necessity. Often what I end up doing is using these symbols to represent the annihilation of man and the creation of dog. In the above image, however, I decided to annihilate a cross as a sort of visual pun about its similarity with the dagger symbol. Notice that my sona is between parenthesis, which implies it's being created after the annihilation of the cross, or maybe of religion (note that operators act starting with the rightmost one and proceeding to the left, so the annihilation one would act first on whichever state it acts on).
As a final thing, it's worth noticing that these operators aren't exclusive to quantum mechanics and actually see use in statistical physics as well. Their use is a bit different in that area, however.