The quark flavor changed \[ \to {\rm{u}}\] takes place in \[{\rm{\beta - }}\]decay. Does this mean that the reverse quark flavor changed \[{\rm{u}} \to \] takes place in \[{\rm{\beta + }}\] decay? Justify your response by writing the decay in terms of the quark constituents, noting that it looks as if a proton is converted into a neutron in \[{\rm{\beta + }}\]decay.

Short Answer

Expert verified

Yes, \[u \to d\] flavor change occurs in \[{{\rm{\beta }}^{\rm{ + }}}\]decay.

Step by step solution

01

Concept Introduction

Quarks are divided into six flavors: up, down, charm, weird, top, and bottom. The masses of up and down quarks are the smallest of all quarks.

02

Explanation

Here\[{{\rm{\beta }}^{\rm{ - }}}\]decay is

\[(ud)d \to (ud)u + {e^ - } + {\bar \nu _e}\]

I,\[{{\rm{\beta }}^{\rm{ - }}}\]decay is where we spelled out the neutron and proton in terms of their quark components.

Where, we wrote out the neutron and proton in terms of their quark constituents, i.e. \[{\rm{n = udd and }}{{\rm{p}}^{\rm{ + }}}{\rm{ = udu}}\]. On the other hand, \[{{\rm{\beta }}^{\rm{ + }}}\]decay is given with\[(ud)u \to (ud)d + {e^ + } + {\nu _e}\]

A proton \[{{\rm{p}}^{\rm{ + }}}{\rm{ = udu}}\]has been transformed into a neutrino \[{{\rm{p}}^{\rm{ + }}}{\rm{ = udu}}\]. This reaction may be generated from (1) by moving particles from the right to the left side and "crossing to the opposite side." Because particles transform into their antiparticles in this operation, our electron \[{{\rm{e}}^{\rm{ - }}}\]became a positron \[{{\rm{e}}^{\rm{ + }}}\]and our electron antineutrino \[{{\rm{\bar \nu }}_{\rm{e}}}\]became a neutrino \[{{\rm{\nu }}_{\rm{e}}}\]. In most cases, a response can occur in both directions. We infer that in \[{{\rm{\beta }}^{\rm{ + }}}\]decay, the reverse flavor change happens.

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Most popular questions from this chapter

Suppose a \[{{\rm{W}}^{\rm{ - }}}\]created in a bubble chamber lives for \[{\rm{5}}{\rm{.00 \times 1}}{{\rm{0}}^{{\rm{ - 25}}}}{\rm{\;s}}\]. What distance does it move in this time if it is traveling at \[{\rm{0}}{\rm{.900c}}\]? Since this distance is too short to make a track, the presence of the \[{{\rm{W}}^{\rm{ - }}}\]must be inferred from its decay products. Note that the time is longer than the given \[{{\rm{W}}^{\rm{ - }}}\]lifetime, which can be due to the statistical nature of decay or time dilation.

Explain how the weak force can change strangeness by changing quark flavor.

(a) How much energy would be released if the proton did decay via the conjectured reaction \({\rm{p}} \to {\pi ^{\rm{0}}}{\rm{ + }}{{\rm{e}}^{\rm{ + }}}\)?

(b) Given that the \({\pi ^{\rm{0}}}\) decays to two \(\gamma {\rm{ s}}\) and that the \({{\rm{e}}^{\rm{ + }}}\) will find an electron to annihilate, what total energy is ultimately produced in proton decay?

(c) Why is this energy greater than the proton’s total mass (converted to energy)?

The mass of a theoretical particle that may be associated with the unification of the electroweak and strong forces is\[{\rm{1}}{{\rm{0}}^{{\rm{14}}}}{\rm{ GeV/}}{{\rm{c}}^{\rm{2}}}\]. (a) How many proton masses is this? (b) How many electron masses is this? (This indicates how extremely relativistic the accelerator would have to be in order to make the particle, and how large the relativistic quantity γ would have to be.)

Theorists have had spectacular success in predicting previously unknown particles. Considering past theoretical triumphs, why should we bother to perform experiments?

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