Particle Physics Flashcards
The K– meson has strangeness –1.
(i) State the quark composition of a meson.
quark antiquark pair
The K– meson has strangeness –1.
State the baryon number of the K– meson.
0
What is the quark composition of the K– meson?
anti-up strange
State the quark composition of a proton
uud
A change in quark identity is involved in electron capture.
(i) Explain what is meant by electron capture.
an atomic/orbital/shell electron
interacts with a proton in the nucleus (via the weak interaction)
Give an example of an exchange particle other than a W+
or W– particle, and
state the fundamental force involved when it is produced.
Z0 with the weak interaction
gluons or pions with the strong nuclear force
γ photons with electromagnetic interaction
gravitons with gravity
State what roles exchange particles can play in an interaction.
transfers energy
transfers momentum
transfers force
(sometimes) transfers charge any two
State the quark structure of an antibaryon
consists of 3 antiquarks
Give one property of an antiparticle that is the same for its corresponding particle and
one property that is different.
same (rest) mass (energy)
difference eg baryon number/charge
Name two baryons
any two eg proton, neutron
State the quark structure of the pion
up, antidown
The K+ kaon is a strange particle. Give one characteristic of a strange particle that
makes it different from a particle that is not strange.
contains a strange quark
or longer half life than expected
or decays by weak interaction
name the particles in the following list that may be affected by the weak
interaction.
positron, neutron, neutrino, positive pion
name the particles in the following list that may be affected by the
electromagnetic force.
electron, proton, negative muon
Sub-atomic particles can either be hadrons or leptons.
State one difference between these two groups of particles.
leptons do not experience the strong interaction but
hadrons do or hadrons not fundamental/made of quarks
and leptons are not
Give an example of a non-strange hadron and an example of a lepton.
hadron eg proton, neutron, pion (1)
lepton eg electron, neutrino
Hadrons can be further divided into two groups. Name these two groups and state a
difference between them.
baryons (1)
mesons (1)
baryons made from three quarks (or 3 antiquarks),
mesons a quark, antiquark pair or baryons, baryon
number is +1 or –1 mesons 0
What property defines a hadron?
particles that experience the strong (nuclear) force/interaction
What is the quark structure of a baryon?
particles composed of three quarks
What is the quark structure of a meson?
particles composed of a quark and an antiquark
State one similarity and one difference between a particle and its antiparticle.
similarity: but the same (rest) mass or rest energy
difference: opposite quantum states eg charge
The quark model was developed to help understand hadrons. Quarks cannot exist
separately, they form combinations.
(a) (i) List the three combinations that quarks can form.
q anti-q, q q q, anti-q anti-q anti-q
Give the quark combination for a positive pion, π
+ and an antiproton,
i) up anit-d
ii) anti-d anti-u anti-u
What is the virtual exchange particle used by electromotive force?
γ photon
State two differences between the exchange particles used by the weak interaction
and used by the electromagnetic force.
γ is massless
γ has infinite range
γ does not carry charge
State what is meant by an antiparticle.
all properties/quantum numbers (e.g. charge, strangeness)
are opposite
