J3 HL Quarks

7/23/2019 J3 HL Quarks

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Option J: Particle physics

J3 Quarks

This part of Option J has already been covered in

Option D5 Quarks.

It is replicated here without any changes.


2/20

J.3.1 List the six types of quark.J.3.2 State the content, in terms of quarks and

antiquarks, of hadrons (that is, baryons and

mesons.

J.3.3 State the quark content of the proton and

the neutron.J.3.! "efine baryon number and app#y the

conser$ation of baryon number.

J.3.% "educe the spin structure of hadrons (that

is, baryons and mesons. &n#y an e#ementary

discussion in terms of 'spin up and 'spindo)n is required. See ".!.! abo$e for

detai#s.


J3 Quarks


3/20

List the six types of quark.*ou ha$e a#ready been introduced to the six

quarks+

Quarks participate in the stron force )hose

carrier is the #uon.


J3 Quarks

Quark

Flavor Symbol Charge

Up u + 2!

"o#n $ % &!

Strange s % &!

Charm c + 2!

'ottom b % &!

(op t + 2!

)nti*uark

Symbol Charge

u % 2!

$ + &!

s + &!

c % 2!

b + &!

t % 2!


4/20

State the content, in terms of quarks andantiquarks, of hadrons (that is, baryons and

mesons.

- ha$ronis a partic#e that participates in the

stron force.

Since quarks participate in the stron force, andsince baryons and mesons are made of quarks,

baryons and mesons are hadrons.

-baryonis made of three quarks (qqq. -n

antibaryon is made of three antiquarks (qqq.

-mesonis made up of a quark and an antiquark(qq+


J3 Quarks

FYI

- singlequark cannot be iso#ated. e )i## ta#k

about quark confineent#ater. /asica##y,

confinement states that you cannot separate asin#e quark from a hadron.


5/20

State the quark content of the proton and theneutron.

- proton is a baryon made up of t)o up quarks and

a do)n quark.p0 (uud.

- neutron is a baryon made up of one up quark and

t)o do)n quarks. n0 (udd.


J3 Quarks

-4L+

Sho) that the chare of a proton is 51, and that

the chare of a neutron is 6.

S&L789&:+

8he chare of an up quark is 52;3.

8he chare of a do)n quark is


6/20

"efine baryon number and app#y the conser$ationof baryon number.

8he baryon number of a quark is 51;3. 8he baryon

number of an antiquark is 89>+ hat is the baryon number of a proton

and an antiproton?

S&L789&:+

4roton 0 uud + 51;3 5 51;3 5 51;3 0 51.

-ntiproton 0 uud +


7/20

"educe the spin structure of hadrons (that is,baryons and mesons.

8he spin of a quark (or antiquark is spin up(

0 1;2 or spin $o#n(0 + "educe the possib#e spin structures of

a baryon+

S&L789&:+ - baryon is (qqq+

4ossibi#ity 1+ 51;2 5 51;2 5 51;2 0 53;2.

4ossibi#ity 2+ 51;2 5 51;2 5


8/20


8he spin of a quark (or antiquark is spin up(

0 1;2 or spin $o#n(0 + "educe the possib#e spin structures of

a meson+

S&L789&:+ - meson is (qq+

4ossibi#ity 1+ 51;2 5 51;2 0 51.

4ossibi#ity 2+ 51;2 5


9/20



J3 Quarks

Pauli says they can,t have i$entical

*uantum numbers- (heir colors $ier-

) proton has a *uark structure o uu$-

.ach *uark has a spin o /-

0 t#o o the three *uarks has a spin o

+ / an$ the other a spin o 1 / the proton

has a spin o /-


10/20

J.3.A xp#ain the need for co#or in forminbound states of quarks.

J.3.B State the co#or of quarks and #uons.

J.3.C &ut#ine the concept of straneness.

J.3.D "iscuss quark confinement.

J.3.16 "iscuss the interaction that bindsnuc#eons in terms of the co#or force bet)een

quarks.


J3 Quarks


11/20

xp#ain the need for co#or in formin boundstates of quarks.

8)o e#ectrons repe#, yet an e#ectron and a

positron (or proton attract. 8o exp#ain such

interactions )e use the mode# of Echare,F and

i$e chares either a (5 or a (G $a#ue.Quarks, on the other hand, seem to sho) three

types of chare, rather than t)o. - mode# usin

(5 and (


12/20

State the co#or of quarks and #uons.Just as (5 and (


13/20

State the co#or of quarks and #uons.I#uons, the stron force carrier, ha$e t)o co#ors

and are not )hite (and thus ha$e a non


14/20

&ut#ine the concept of straneness.8he straneness number !of a baryon is re#ated

to the number of strane quarks the partic#e has

and is found usin the formu#a


J3 Quarks

strangeness S!0 -ntistrane quarks

< strane quarks

-4L+ 8he #ambda Hero partic#e (6 is a

baryon ha$in the quark combo of (uds. hat is

its chare? hat is its straneness?

S&L789&:+

Krom a pre$ious tab#e the chares are u 0 52;3,

d 0


15/20

&ut#ine the concept of straneness.


J3 Quarks

(he 1is a ha$ron because it is compose$

o *uarks-


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J3 Quarks

(he proton is compose$ o uu$-


17/20



J3 Quarks

0 is sss3 then the reaction can be

#ritten in terms o *uarks as ollo#s:

su + uu$ $s + us + sss(he let has an s3 u3 an$ $ let-

(he right also has an s3 u3 an$ $ let-(he *uarks are balance$ on each si$e-


18/20

"iscuss quark confinement.Quark confinement means

that )e cannot e$er

separate a sin#e quark

from a baryon or a

meson./ecause of the nature

of the stron force

ho#din the quarks

toether )e need to

pro$ide an enery that

is proportiona# to the

separation.

$entua##y, that enery is so $ast that a ne)

quark


19/20

"iscuss quark confinement.


J3 Quarks

Origin

al

meson

4e#l

y%cr

eate$

meso

n

Quar

k%

anti

*uar

kpa

ir

create$

+ro

m

energy

nee$e$

+or

sepa

ration


20/20

"iscuss the interaction that binds nuc#eons interms of the co#or force bet)een quarks.

8he residua# co#or force of the #uons that ho#d

the quarks toether is )hat is kno)n as the

stron force.

8hus nuc#earreactors and

bombs represent

on#y the

residua# enery

in the #uon

interaction

bet)een quarks.


J3 Quarks

J3 HL Quarks

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