Particle Conservation Laws

en · official · sha256:e25099221112abfa16d031283835c5e625c14c2760b7b6c7d5845c1589423dbd

<para id="fs-id1172100492398">This process conserves charge, energy, and momentum. However, it does not occur because it violates the law of baryon number conservation. This law requires that the total baryon number of a reaction is the same before and after the reaction occurs. To determine the total baryon number, every elementary particle is assigned a <term id="term-00001">baryon number</term> <emphasis effect="italics">B</emphasis>. The baryon number has the value <m:math><m:mrow><m:mi>B</m:mi><m:mo>=</m:mo><m:mo>+</m:mo><m:mn>1</m:mn></m:mrow></m:math> for baryons, –1 for antibaryons, and 0 for all other particles. Returning to the above case (the decay of the neutron into an electron-positron pair), the neutron has a value <m:math><m:mrow><m:mi>B</m:mi><m:mo>=</m:mo><m:mo>+</m:mo><m:mn>1</m:mn><m:mo>,</m:mo></m:mrow></m:math> whereas the electron and the positron each has a value of 0. Thus, the decay does not occur because the total baryon number changes from 1 to 0. However, the proton-antiproton collision process</para>

en · official · sha256:f9b2d395227bd84c4c98c0a7fb441ee0bcd5922bed6d348309bdcae0615209f6

<definition id="fs-id1172098318558"> <term>baryon number</term> <meaning id="fs-id1172098515808">baryon number has the value <m:math><m:mrow><m:mi>B</m:mi><m:mo>=</m:mo><m:mo>+</m:mo><m:mn>1</m:mn></m:mrow></m:math> for baryons, <m:math><m:mrow><m:mo>–</m:mo><m:mn>1</m:mn></m:mrow></m:math> for antibaryons, and 0 for all other particles and is conserved in particle interactions</meaning> </definition>

Referencing norms: AllConservedInteractionCanOccur, BaryonNumberViolationForbids, BaryonsHaveBaryonNumberOne, MesonsHaveBaryonNumberZero, total_baryon_number_after, total_baryon_number_before

en · official · sha256:47b55443eee246ea8cb7d4f7a6f96561f7f0076cefc5b3b888ec44f19d75165b

<para id="fs-id1172100977371">In previous chapters, we encountered other conservation laws as well. For example, charge is conserved in all electrostatic phenomena. Charge lost in one place is gained in another because charge is carried by particles. No known physical processes violate charge conservation. In the next section, we describe three less-familiar conservation laws: baryon number, lepton number, and strangeness. These are by no means the only conservation laws in particle physics.</para>

Referencing norms: ChargeViolationForbids, total_charge_after, total_charge_before

en · official · sha256:0984f9c874418e9b33acb782f41d15dbb387a29937ad2a92eb90126ada9484dc

<definition id="fs-id1172098391391"> <term>lepton number</term> <meaning id="fs-id1172100988168">electron-lepton number <m:math><m:mrow><m:msub><m:mi>L</m:mi><m:mi>e</m:mi></m:msub><m:mo>,</m:mo></m:mrow></m:math> the muon-lepton number <m:math><m:mrow><m:msub><m:mi>L</m:mi><m:mi>μ</m:mi></m:msub><m:mo>,</m:mo></m:mrow></m:math> and the tau-lepton number <m:math><m:mrow><m:msub><m:mi>L</m:mi><m:mi>τ</m:mi></m:msub></m:mrow></m:math> are conserved separately in every particle interaction</meaning> </definition>

Referencing norms: ElectronLeptonNumberViolationForbids, electron_lepton_number_after, electron_lepton_number_before

en · official · sha256:38e91f6f813daebe351d99beee50cc121f8dc68c3644add1b4b44cb12b320fa1

<definition id="fs-id1172098391720"> <term>strangeness</term> <meaning id="fs-id1172101033869">particle property associated with the presence of a strange quark</meaning> </definition>

Referencing norms: StrangenessConservedInStrongInteraction, StrangenessViolatedInStrongInteraction, strangeness_after, strangeness_before, strong_interaction, weak_interaction