Deck 44: Quarks, Leptons, and the Big Bang

Question 1

A particle with spin angular momentum is called a:

A) lepton
B) hadron
C) fermion
D) boson
E) electron

Answer 1

fermion

Question 2

$\pi$ ⁺ represents a pion (a meson), $\mu$ ^- represents a muon (a lepon), v_e represents an electron neutrino (a lepton), and v _$\mu$ and p represents a proton a muon neutrino (a lepton). Which of the following decays might occur?

A) ( $\pi$ ⁺ $\rightarrow$$\mu$ ^- + v _$\mu$ )
B) ( $\pi$ ⁺ $\rightarrow$$\mu$ ⁺ + v_e)
C)
D)
E) ( $\pi$ ⁺ $\rightarrow$$\mu$ ⁺ + v _$\mu$ )

Answer 2

( $\pi$ ⁺ $\rightarrow$$\mu$ ⁺ + v _$\mu$ )

Question 3

A particle with spin angular momentum is called a:

A) lepton
B) hadron
C) fermion
D) boson
E) electron

Answer 3

boson

Question 4

When a kaon decays via the strong interaction the products must include a:

A) baryon
B) lepton
C) strange particle
D) electron
E) neutrino

Question 5

A positron cannot decay into three neutrinos. Of the following conservation laws, which would be violated if it did?

A) Energy
B) Baryon number
C) Lepton number
D) Linear momentum
E) Angular momentum

Question 6

All leptons interact with each other via the:

A) strong force
B) weak force
C) electromagnetic force
D) strange force
E) none of these

Question 7

A particle can decay to particles with greater rest mass:

A) only if antiparticles are produced
B) only if photons are also produced
C) only if neutrinos are also produced
D) only if the original particle has kinetic energy
E) never

Question 8

An electron participates in:

A) the strong force only
B) the strong and weak forces only
C) the electromagnetic and gravitational forces only
D) the electromagnetic, gravitational, and weak forces only
E) the electromagnetic, gravitational, and strong forces only

Question 9

A neutral muon cannot decay into two neutrinos. Of the following conservation laws, which would be violated if it did?

A) Energy
B) Baryon number
C) Linear Momentum
D) Angular momentum
E) None of the above

Question 10

An example of a boson is a:

A) photon
B) electron
C) neutrino
D) proton
E) neutron

Question 11

An example of a fermion is a:

A) photon
B) pion
C) neutrino
D) kaon
E) none of these

Question 12

All particles with spin angular momentum :

A) interact via the strong force
B) travel at the speed of light
C) obey the Pauli exclusion principle
D) have non-zero rest mass
E) are charged

Question 13

The stability of the proton is predicted by the laws of conservation of energy and conservation of:

A) momentum
B) angular momentum
C) baryon number
D) lepton number
E) strangeness

Question 14

Which of the following particles has a lepton number of +1?

A) e⁺
B) ( $\mu$ ⁺)
C) ( $\mu$ ^-)
D)
E) p

Question 15

The interaction $\pi$ ^- + p $\rightarrow$$\pi$ ^- + $\Sigma$ ⁺ violates the principle of conservation of:

A) baryon number
B) lepton number
C) strangeness
D) angular momentum
E) none of these

Question 16

Which of the following particles is stable?

A) Neutron
B) Proton
C) Pion
D) Muon
E) Kaon

Question 17

Strangeness is conserved in:

A) all particle decays
B) no particle decays
C) all weak particle decays
D) all strong particle decays
E) some strong particle decays

Question 18

Different types of neutrinos can be distinguished from each other by:

A) the directions of their spins
B) the leptons with which they interact
C) the baryons with which they interact
D) the number of photons that accompany them
E) their baryon numbers

Question 19

The interaction $\pi$ ^- + p $\rightarrow$ K^- + $\Sigma$ ⁺ violates the principle of conservation of:

A) baryon number
B) lepton number
C) strangeness
D) angular momentum
E) none of these

Question 20

Which of the following particles has a lepton number of zero?

A) e⁺
B) ( $\mu$ ⁺)
C) v_e
D)
E) p

Question 21

The quark content of a $\pi$ ⁺ meson is:

A) uu
B)
C) ud
D)
E)

Question 22

A certain process produces mesons that decay with a lifetime of 6 *10^-10 s. The decay is a result of:

A) the gravitational interaction
B) the weak interaction
C) the electromagnetic interaction
D) the strong interaction
E) some combination of the above

Question 23

In terms of quark content a beta decay can be written:

A) udd $\rightarrow$ uud + e^- + $\nu$
B) udd $\rightarrow$ udd + dd + $\nu$
C) udd $\rightarrow$ udd + dd + e^-
D) udd $\rightarrow$ uud + ud + $\nu$
E) udd $\rightarrow$ uud + ud + e^- + $\nu$

Question 24

Messenger particles of the electromagnetic interaction are called:

A) gluons
B) photons
C) W and Z
D) gravitons
E) pions

Question 25

Two particles interact to produce only photons, with the original particles disappearing. The particles must have been:

A) mesons
B) strange particles
C) strongly interacting
D) leptons
E) a particle, antiparticle pair

Question 26

The up quark u has charge +2/3 and strangeness 0; the down quark d has charge -1/3 and strangeness 0; the strange quark s has charge -1/3 and strangeness -1. This means there can be no meson with:

A) charge 0 and strangeness -1
B) charge -1 and strangeness -1
C) charge +1 and strangeness -1
D) charge -1 and strangeness +1
E) charge 0 and strangeness +1

Question 27

The baryon number of a quark is:

A) 0
B) 1/2
C) 1/3
D) 2/3
E) 1

Question 28

Compared to the lifetimes of particles that decay via the weak interaction, the lifetimes of particles that decay via the strong interaction are:

A) 10^-12 times as long
B) 10^-23 times as long
C) 10²⁴ times as long
D) 10¹² times as long
E) about the same

Question 29

Two baryons interact to produce pions only, the original baryons disappearing. One of the baryons must have been:

A) a proton
B) an omega minus
C) a sigma
D) an antiparticle
E) none of these

Question 30

A baryon with strangeness 0 decays via the strong interaction into two particles, one of which is a baryon with strangeness +1. The other might be:

A) a baryon with strangeness 0
B) a baryon with strangeness +1
C) a baryon with strangeness -1
D) a meson with strangeness +1
E) a meson with strangeness -1

Question 31

The up quark u has charge +2e/3 and strangeness 0; the down quark d has charge -e/3 and strangeness 0; the strange quark s has charge -e/3 and strangeness -1. This means there can be no baryon with:

A) charge 0 and strangeness 0
B) charge -e and strangeness -1
C) charge +e and strangeness -1
D) charge +e and strangeness -2
E) charge 0 and strangeness +2

Question 32

In order of increasing strength the four basic interactions are:

A) gravitational, weak, electromagnetic, and strong
B) gravitational, electromagnetic, weak, and strong
C) weak, gravitational, electromagnetic, and strong
D) weak, electromagnetic, gravitational, and strong
E) weak, electromagnetic, strong, and gravitational

Question 33

A certain process produces baryons that decay with a lifetime of 4 *10^-24 s. The decay is a result of:

A) the gravitational interaction
B) the weak interaction
C) the electromagnetic interaction
D) the strong interaction
E) some combination of the above

Question 34

The two basic interactions that have finite ranges are:

A) electromagnetic and gravitational
B) electromagnetic and strong
C) electromagnetic and weak
D) gravitational and weak
E) weak and strong

Question 35

Quarks are the constituents of:

A) all particles
B) all leptons
C) all strongly interacting particles
D) only strange particles
E) only mesons

Question 36

A baryon with strangeness -1 decays via the strong interaction into two particles, one of which is a baryon with strangeness 0. The other might be:

A) a baryon with strangeness 0
B) a baryon with strangeness +1
C) a meson with strangeness -1
D) a meson with strangeness +1
E) a meson with strangeness 0

Question 37

The quark content of a proton is:

A) uuu
B) uud
C) udd
D) ddd
E) uds

Question 38

Any baryon is a combination of:

A) three quarks
B) two quarks and an antiquark
C) one quark and two antiquarks
D) one quark and one antiquark
E) two quarks

Question 39

All known quarks have:

A) charges that are multiples of e and integer baryon numbers
B) charges that are multiples of e and baryon numbers that are either +1/3 or -1/3
C) charges that are multiples of e/3 and integer baryon numbers
D) charges that are multiples of e/3 and baryon numbers that are either +1/3 or -1/3
E) charges that are multiples of 2e/3 and baryon numbers that are either +1/3 or -1/3

Question 40

Any meson is a combination of:

A) three quarks
B) two quarks and an antiquark
C) one quark and two antiquarks
D) one quark and one antiquark
E) two quarks

Question 41

If dark matter did not exist it is likely that:

A) the universe would expand forever
B) the universe would begin contracting soon
C) the night sky would be brighter
D) the night sky would be darker
E) we would be able to see the center of the universe

Question 42

Dark matter suspected to exist in the universe because:

A) the night sky is dark between stars
B) the orbital period of stars in the outer parts of a galaxy is greater than the orbital period of stars near the galactic center
C) the orbital period of stars in the outer parts of a galaxy is less than the orbital period of stars near the galactic center
D) the orbital period of stars in the outer parts of a galaxy is about the same as the orbital period of stars near the galactic center
E) all galaxies have about the same mass

Question 43

Hubble's law is evidence that:

A) the speed of light is increasing
B) the universe is expanding
C) the Earth is slowing down in its orbit
D) galaxies have rotational motion
E) none of the above

Question 44

A down quark can be changed into an up quark (plus other particles perhaps) by:

A) the gravitational interaction
B) the electromagnetic interaction
C) the weak interaction
D) the strong interaction
E) none of these

Question 45

The color theory explains why quarks:

A) form particles in pairs and triplets
B) have charge that is a multiple of e/3
C) have spin
D) have mass
E) none of the above

Question 46

Messenger particles of the strong interaction are called:

A) gluons
B) photons
C) W and Z
D) gravitons
E) pions

Question 47

The velocities of distant objects in the universe indicate that the time elapsed since the big bang is about:

A) 10⁵ y
B) 10¹⁰ y
C) 10¹⁵ y
D) 10²⁰ y
E) 10²⁵ y

Question 48

Messenger particles of the weak interaction are called:

A) gluons
B) photons
C) W and Z
D) gravitons
E) pions

Question 49

The intensity of the microwave background radiation, a remnant of the big bang:

A) is greatest in directions toward the center of the galaxy
B) is leasr in directions toward the center of the galaxy
C) is proportional to the reciprocal of the distance from us
D) is proportional to the square of the distance from us
E) is mearly the same in all directions

Question 50

Color is carried by:

A) only quarks
B) only leptons
C) only quarks and leptons
D) only quarks and gluons
E) only photons and gluons

Question 51

Objects in the universe are receding from us with a speed that is proportional to:

A) the reciprocal of their distance from us
B) the reciprocal of the square of their distance from us
C) their distance form us
D) the square of their distance from us
E) their distance from the center of the universe

Question 52

As a result of the big bang there is, in addition to the microwave background radiation, a uniform distribution of background:

A) electrons
B) quarks
C) gluons
D) neutrinos
E) atoms