Large Hadron Collider finds new particle

[Sam Wormley]

Large Hadron Collider finds new particle

http://www.telegraph.co.uk/science/large-hadron-collider/8973235/Large-Hadron-Collider-finds-new-particle.html

> Unlike the Higgs the new boson, known as Chi (the Greek X symbol) b (3p), consists of two parts – an elementary particle known as a "beauty" quark and its opposite antiquark, which are bound together by a "strong force".

> The particle had been widely predicted but had never actually been observed by physicists.

See:
http://www.telegraph.co.uk/science/large-hadron-collider/8973235/Large-Hadron-Collider-finds-new-particle.html

[Sam Wormley]

Observation of a new chi_b state in radiative transitions to Upsilon(1S)
and Upsilon(2S) at ATLAS
http://arxiv.org/abs/1112.5154

The chi_b(nP) quarkonium states are produced in proton-proton collisions
at the Large Hadron Collider (LHC) at sqrt(s) = 7 TeV and recorded by
the ATLAS detector. Using a data sample corresponding to an integrated
luminosity of 4.4 fb^-1, these states are reconstructed through their
radiative decays to Upsilon(1S,2S) with Upsilon->mu+mu-. In addition to
the mass peaks corresponding to the decay modes
chi_b(1P,2P)->Upsilon(1S)gamma, a new structure centered at a mass of
10.539+/-0.004 (stat.)+/-0.008 (syst.) GeV is also observed, in both the
Upsilon(1S)gamma and Upsilon(2S)gamma decay modes. This is interpreted
as the chi_b(3P) system.

See: http://arxiv.org/pdf/1112.5154v1

[Chris Richardson]

It's not "new" in the sense of not having predicted.

It's also not elementary, being composed of a beauty quark
and its antiquark.

It's also a boson.

http://www.noodls.com/viewNoodl/12572957/university-of-birmingham/new-particle-at-the-large-hadron-collider-discovered-by-atla

[Y.Porat]

On Dec 22, 6:46 pm, Chris Richardson <r...@localhost.localdomain>
wrote:

> It's not "new" in the sense of not having predicted.
>
> It's also not elementary, being composed of a beauty quark
> and its antiquark.
>
> It's also a boson.
>

> http://www.noodls.com/viewNoodl/12572957/university-of-birmingham/new...

----------------------
The same Bull .........
as the previous ones !!!
it seems they refuse to separate
from the virtual '' milk cow''' of their income
why wonder ?? (:-)

Y. Porat
---------------------------------

[Marco Ponte]

Maybe a silly question, but how can this particle (and mesons in
general) be composed of a quark and its anti-quark counterpart ? Don't
they destrou each other ?

[Poutnik]

In article <c38262b6-a79e-4ab3-97eb-
68cda1...@f1g2000yqi.googlegroups.com>, marcop...@gmail.com
says...

>

>
> Maybe a silly question, but how can this particle (and mesons in
> general) be composed of a quark and its anti-quark counterpart ? Don't
> they destrou each other ?

I would say they have different color charge
and cannot anihilate therefore.

Quark color / color charge is a quantum number,
not related to visual effects of course,
but named like that because of having in common
some behavior aspects.

http://en.wikipedia.org/wiki/Color_charge
http://en.wikipedia.org/wiki/Quantum_chromodynamics

--
Poutnik

[Y.Porat]

On Dec 23, 3:58 am, Poutnik <pout...@privacy.invalid> wrote:
> In article <c38262b6-a79e-4ab3-97eb-
> 68cda15f1...@f1g2000yqi.googlegroups.com>, marcopont...@gmail.com

> says...
>
>
>
> > Maybe a silly question, but how can this particle (and mesons in
> > general) be composed of a quark and its anti-quark counterpart ? Don't
> > they destrou each other ?
>
> I would say they have different color charge
> and cannot anihilate therefore.
>
> Quark color / color charge is a quantum number,
> not related to visual effects of course,
> but named like that because of having in common
> some behavior aspects.
>
> http://en.wikipedia.org/wiki/Color_chargehttp://en.wikipedia.org/wiki/Quantum_chromodynamics
>
> --
> Poutnik

---------------
it depends if the quark was eating for breakfast
a yellow jelly or a red one !!
Y.Porat
---------------------------

[Sam Wormley]

On 12/22/11 8:46 PM, Chris Richardson wrote:
> It's not "new" in the sense of not having predicted.
>
> It's also not elementary, being composed of a beauty quark
> and its antiquark.
>
> It's also a boson.

Quark-antiquark pairs are call mesons (bosonic hadrons) and are
unstable, with the longest-lived lasting for only a few tens of
nanoseconds.

>
> http://www.noodls.com/viewNoodl/12572957/university-of-birmingham/new-particle-at-the-large-hadron-collider-discovered-by-atla
>

[PD]

On 12/23/2011 5:01 AM, Marco Ponte wrote:

>
> Maybe a silly question, but how can this particle (and mesons in
> general) be composed of a quark and its anti-quark counterpart ? Don't
> they destrou each other ?

Not silly at all. Sometimes they do.
A positively charged pion is made up dominantly of an up quark and an
anti-down quark, so those won't annihilate.
But a neutral pion is made up dominantly of a mixture of up and anti-up
and down and anti-down, and that does decay into photons.

How long that takes depends on the strength of the interaction.

You can see the same thing with positronium, which is a short-lived
"atom" of an electron and a positron.

[Poutnik]

In article <jd27fk$aa7$1...@speranza.aioe.org>, thedrap...@gmail.com
says...

>

> But a neutral pion is made up dominantly of a mixture of up and anti-up
> and down and anti-down, and that does decay into photons.
>
> How long that takes depends on the strength of the interaction.
>

I guess they have to have the same color charge ( red/anti red/ etc )
to anihilate.

If they do not have it,
they may need to wait to weak interaction decay mechanism,
that does not keep color charge.

--
Poutnik

[Tom Roberts]

On 12/23/11 12/23/11 5:01 AM, Marco Ponte wrote:
> Maybe a silly question, but how can this particle (and mesons in
> general) be composed of a quark and its anti-quark counterpart ? Don't

> they destroy each other ?

It's not a silly question.

There are quite a few mesons comprised of a quark and its anti-quark: pi0, rho0,
eta, omega, phi, J/psi, upsilon, theta(?), etc. All are unstable, but some of
them are quite long-lived (well, for a meson). It seems that while these mesons
are bound q qbar states, the quarks are much smaller than the meson itself, and
have a relatively hard time finding each other to annihilate (speaking loosely).
Of course this is all relative, and even the longest-lived meson of this type
(pi0) has a lifetime of only 8E-17 seconds. When one compares that to the
lifetimes of pi+ and pi-, which involve the same u and d quarks (but not q
qbar), the pi0 decays about a billion times faster, implying that q qbar
annihilation is important.

There is a pattern in the decays of these q qbar mesons: the lowest q qbar meson
of a particular quark decays into mesons not involving q, so indeed it appears
the q and qbar annihilate. There are two types of higher-mass q qbar mesons:
those that decay predominantly into a lower-mass q qbar state, and those that
decay predominantly into two mesons involving q and qbar. So, for instance, the
J/psi decays into many different hadronic and leptonic modes, none of which
involve D mesons (the J/psi is a c cbar state, and the D mesons have one c
quark). The psi' [psi(2S)] decays mostly into J/psi + other stuff; the psi(3770)
decays almost exclusively into D Dbar. So it seems that for this last particle
the two c quarks do not annihilate, but merely separate into other (D) mesons.

This pattern can be explained in terms of energy and angular-
momentum conservation. In all cases, the lowest q qbar state is
lower mass than the sum of a q meson plus a qbar meson, so energy
conservation prohibits such a decay; these states tend to be
much shorter lived than their q-meson cousins, again implying
that q qbar annihilation is important in their decay.

In the case being discussed, the Chi_b is comprised of a bottom and anti-bottom.
It was identified via bottom mesons, so it appears that its decay does not
involve the bottom quarks annihilating each other. The paper does not give a
measured width, but if the width is comparable to similar mesons, it would be on
the order of 100 MeV, corresponding to a lifetime of about 1E-23 sec. The size
of such a meson is on the order of a fraction of a Fermi, and this lifetime is
on the order of the time it takes light to cross such a distance.


Note that the detail of this description is one of the reasons that the standard
model is viewed with such high esteem. There are many qualitative arguments such
as this, plus an enormous number of quantitative predictions for scattering
amplitudes and decay rates that are in excellent agreement with observations.
The standard model is nearly as well-established as is the atomic theory of
matter; indeed the SM is a level deeper than the latter, and provides a
foundation for atomic theory.


Tom Roberts

[Y.Porat]

------------------
only the foundation??(:-)

-------------------------------