Hopefully this one will occupy you longer.

I am a ghost
discarnate and sneaky.
Invisible at most.
Catching me is tricky.

I am an awkward loner
team work is not my thing at all.
To cooperate with my persona
you need huge meeting hall.

I am very fair
and never pick a side.
You know me, I am everywhere.
But who am I?


It is a

Neutrino

I am a ghost
discarnate and sneaky.
Invisible at most.
Catching me is tricky.

Neutrinos are hard to catch and not visible to the human eye.

I am an awkward loner
team work is not my thing at all.

Neutrinos do not interact with each other, nor with most other particles.

To cooperate with my persona
you need huge meeting hall.

The huge meeting hall is a neutrino detector.

I am very fair
and never pick a side.

Since they don't collide with other particles, neutrinos don't change direction. Update after OP's clarification: not picking a side is about being neutral (having no positive or negative charge).

You know me, I am everywhere.

True :-)

• Hi GOTO :) Could it refer to en.wikipedia.org/wiki/Spin_%28physics%29 (the picking a side thing?) – d'alar'cop Nov 21 '14 at 11:45
• @d'alar'cop That could surely be... how would you explain that? – GOTO 0 Nov 21 '14 at 12:08
• Not really sure... maybe "they don't chose a side" because the spin of an atom isn't know until it's observed or something? (Quantum Mechanics - I'm not expert :p) – d'alar'cop Nov 21 '14 at 12:09
• not picking a side is about being neutral :) no positive or negative charge – zlobi.wan.kenobi Nov 21 '14 at 12:28
• all other clues have correct interpretation => solved :) – zlobi.wan.kenobi Nov 21 '14 at 12:29

Maybe it can be

Argon (Air gas)

Because:

I am a ghost discarnate and sneaky. Invisible at most. Catching me is tricky.

You can't obviously see it, and you can't catch it easily

I am an awkward loner team work is not my thing at all. To cooperate with my persona you need huge meeting hall.

Since it is about 1% of total air, you need a lot of air in order to have a significantly high concentration of Argon (that's why I think you need a huge meeting hall, because it has lot of air in it). Teamwork is not its thing because its name derives from the Greek word "lazy"

I am very fair and never pick a side. You know me, I am everywhere. But who am I?

It is inert, so it doesn't react to anything. It's everywhere because it is in air.

• what about the "huge meeting hall"...? nice answer btw – d'alar'cop Nov 21 '14 at 11:16
• You are very close in your interpretation, indeed. But what about the huge meeting hall? :) And is Argon really everywhere? – zlobi.wan.kenobi Nov 21 '14 at 11:17
• "To cooperate with my persona" (In order to work with it) "you need huge meeting hall." (A huge meeting hall contains a lot of air, so (relatively) a lot of argon) @zlobi: On average, I think yes. Well, not where vacuum is :P – Andrea Gottardi Nov 21 '14 at 11:19
• @AndreaGottardi Not bad, but it might be a bit too much of a stretch :p – d'alar'cop Nov 21 '14 at 11:24

It could be:

The Higgs Boson

I am a ghost discarnate and sneaky. Invisible at most. Catching me is tricky.

The existence of Higgs has been very difficult to confirm

I am an awkward loner team work is not my thing at all. To cooperate with my persona you need huge meeting hall.

The Higgs is a loner because it is an elementary particle. To find it you need a Large Hadron Collider

I am very fair and never pick a side.

A bit of a stretch, but a team of international scientists work at CERN

You know me, I am everywhere.

The Higgs field is present everywhere

• close, but some details do not fit :) – zlobi.wan.kenobi Nov 21 '14 at 12:30

I might be completely off track, but I believe the answer is

A photon

The sentences that lead me to this conclusion are:

I am a ghost discarnate and sneaky. Invisible at most. Catching me is tricky.

A "ghost" as in "can't be perceived when you touch it". Disincarnate because it has "no" mass, hard to catch because studying it has been historically difficult

To cooperate with my persona you need a huge meeting hall

"a person's perceived or evident personality, as that of a well-known official, actor, or celebrity; personal image; public role." from here.In this sense a photon's persona could be the Sun, thus the "huge meeting hall" to cooperate with it

I am very fair

fair meaning bright

and never pick a side

the particle-wave duality

Can't figure out the other hints

• I like the part with the particle-wave duality :) – zlobi.wan.kenobi Nov 21 '14 at 15:21