In this case a kaon-zero decays to a
quark-weak vertex. (See the figure.) pair. All processes involving photons, and therefore all of the interactions associated with electromagnetism, arise from elementary events of photon creation or photon annihilation. chamber picture of the discovery of omega minus! The key points of a Feynman diagram are the “vertices,” representing those spacetime points at which (in this example) photons are created or absorbed. s ® u
interaction. The Feynman diagrams could be broken into two different “orders” of thinking. quark and an antidown quark, an
In physics, a one-loop Feynman diagram is a connected Feynman diagram with only one cycle ().Such a diagram can be obtained from a connected tree diagram by taking two external lines of the same type and joining them together into an edge.. Examples of several Feynman diagrams. I hope it cleared up a little more about Feynman diagrams, and was maybe useful! In
decays to a proton, an electron and an anti-neutrino via the weak interaction. Lower order diagram. weak vertex and a weak-lepton vertex. quark of the antiproton annihilates with the up quark of the proton emitting a
A xi-zero (uss) decays into a lambda zero (uds) and a pi zero (). Examples of particle interactions described in terms of
In the final state a neutron and an antineutron are produced. In this case there is a collision between a positive kaon (K+) and a proton
EXAMPLES OF FEYNMAN DIAGRAMS WITH THE TIKZ PACKAGE 3 e+ WW q q W+ d0 u0 + H W d u Figure 7. simple electromagnetic vertex. antidown - up pair. To succeed, you will need to put into the standard vertex in Fig. #5 levan, November 10, 2010 at 3:54 p.m. is there an example about loop diagrams (fermion, fermion-boson, gluions) #6 Ole, November 28, 2012 at 5:20 p.m. Feynman diagrams are not pictures of particles flying in space or time. leptons are a first generation pair. So the best you’re going to have to do is get a diagram. In these diagrams, you get the most basic overview of what you need to know, and … Each diagram is seen on two dimensions, one being time and the other being the particular position in space. This is a strong interaction and involves quark gluon vertices only. and an antineutron, omega-minus decays to xi-zero, an
The Feynman diagram for the s to u transition is a combination of two quark-W vertices. antidown quark of the antiproton emits a gluon and the gluon materialize into an
For best results use Firefox. interaction, 6 a sigma plus decays to a proton and a pi-zero via the weak
anti-electron neutrino, 2. pi-plus decays to
interaction. s
corresponding Feynman diagram will be: This is a weak decay of the strange quark. with the creation of an
In a Feynman diagram the particles and the exchange particle are shown. Examples of Interactions - Feynman Diagrams [ Back to main Physics page] [ Fundamental Particles] [ Standard Model] [ Exchange Particles and Forces] The exchange of particles in an interaction can be visualised using Feynman diagrams. The Feynman diagram for the s to u transition is a combination of two quark-W vertices. It is a
A gluon is created and materialises a down quark and an
with the creation of an electron - antineutrino pair. There are 3 kinds of ingredients: external lines, internal lines and propagators. à
As an example, we give a detailed calculation of cross-section for annihilation of electron and positron into a muon pair. u with the creation of a down-antiup
March 25, 2006 Introduction feynMF is a package made by Thorsten Ohl to draw Feynman diagrams in LATEXenvironment.You The Feynman diagram for the d to u transition is a
So what I decided to do was to first write and release this prelude article introducing the readers to Feynman diagrams and giving brief examples about them, with more detailed examples to come in the next article. The number of ways to link an X to two external lines is 4 × 3, and either X could link up to either pair, giving an additional factor of 2. the down quark recombine as a proton. 13. Sample Feynman diagrams for W+4jets production. Feynman diagram for vector boson fusion Higgs production re-sulting in an electron, neutrino, and two quark jets. while for the up quark it is of size +2 3gEM. For example, a more basic diagram like the ones above would be considered a lower order diagram, whereas something more complex falls into higher order. If you’d like to talk, email me at amesett@gmail.com or find me on LinkedIn under Amelia Settembre. never be "seen" in a bubble chamber picture. the up
annihilation to two photons, 8 xi-zero decays to a lambda zero
In this example the up and the antidown quarks in the pi-plus annihilate to
pair. The signalled tracks in the picture above shows the xsi zero decay, in the bubble
p 1 p 2 x 1 x 2 W f 1(x 1;Q2) f 2(x 2;Q2) Figure 8. up quark and the antidown quark recombine as a positive pion. They consist of points, called vertices, which represent the interactions and lines attached to the vertices which represent the fermions and bosons involved in the interaction. Feynman diagram for vector boson fusion Higgs production re-sulting in an electron, neutrino, and two quark jets. to a muon antineutrino, a positron and an electron neutrino, 4 K zero decays to a
In addition to that, the diagrams can be found in varying complexity. lepton-weak vertex. Feynman Diagrams and the Strong Force.
30-Apr. The calculations that eventually got me a Nobel Prize in 2004 would have been literally unthinkable without Feynman diagrams, as would my calculations that established a route to production and observation of the Higgs particle. And this should include the Feynman diagrams associated with this interaction! The arrows demonstrate the way in which the energy flows, or rather, the direction in which the electrons are travelling. Dirac equation, free quantum ﬁelds and construction of Feynman amplitude using Feynman diagrams. and an antineutron, 14. omega-minus decays to xi-zero, an
Feynman rules The Feynman rules tell us how to go from a diagram to the corresponding matrix element (or amplitude) which is necessary to calculate σσσσand ΓΓΓ. The quarks come form the same generation. Similarly, the
One of the most commonly discussed and referenced diagrams is the Feynman diagram, found mostly in quantum particle physics. On that day in Santa Barbara, citing those examples, I told Feynman how important his diagrams had been to me in my work. It is an allowed
This is a weak interaction of the anti-strange quark to an anti-up quark with
The D++ then decays to a proton and a positive
decays to a proton, an electron and an anti-neutrino via the weak interaction. You can’t see particles. combination of quark-W vertex and same generation lepton W vertex. an excited state (D++) are produced. He drew a simple diagram on the blackboard, similar to the one This virtual electron then annihilates with the positron with the emission
neutral kaon and a delta++, 13. antiproton interacts with a proton to produce a neutron
quark of the kaon emits a gluon and the gluon materializes into a down quark and
Richard Feynman developed a technique referred to as Feynman diagrams. It is an allowed diagonal change
Feynman diagrams represent interactions between matter particles (fermions, including quarks and leptons) and their corresponding force carriers (bosons). The Feynman diagram shows a combination of an antiquark-weak vertex and a
from the first generation of the antilepton family. the creation of a W-plus. In this case, one of the quarks in the sigma-zero emits a photon. The basic interaction therefore appears on a Feynman diagram as a “vertex”—i.e., a junction of three lines. A Java program for drawing Feynman diagrams. Feynman diagrams are a pictorial way to keep track of terms in quantum field theory calculations. This event involves only neutral particles and you may think that it could
Each element of a Feynman diagram represents a different term in our calculation. anti-electron neutrino, pi-plus decays to
The corresponding Feynman diagram will be:
JaxoDraw15 Eylül 2007 tarihinde Wayback Machine sitesinde arşivlendi. This is a weak decay of the strange quark. It is an allowed
As one of his first examples, he considered the problem of electron-electron scattering. pi-minus and pi-plus via the weak
anti-down quark. It is an allowed diagonal
electron and an electron antineutrino. Feynman Diagrams Richard Feynman devised a short hand way of writing out particle interactions called Feynman Diagrams. with the creation of a down - antiup pair. to a muon antineutrino, a positron and an electron neutrino, lambda zero decays to a proton and a pi-minus via the weak
8 Descriptive Statistics Concepts Explained Using R, Using Reducible Functions in Math Problems, The Strange Similarity of Neuron and Galaxy Networks, How a dubious math trick became a law of physics, a stock trading analogy. Bowley, Roger (2010).
In this case a neutron
(K0) and
The corresponding Feynman diagram will be: This is a weak decay of the down quark. A general Feynman diagram derived from the expansion of a general Green’s function consists of many connected pieces (subdiagrams) disconnected with each oth-ers. This is an annihilation of a positron and an electron. The anti-strange to anti-up vertex is an allowed diagonal change between
between quark generation: We also can see a quark weak vertex leading to a anti-up and a down quark. Feynman diagrams were able to make progress where no one else could. Feynman’s Remedy In his Pocono Manor Inn talk, Feynman told his fellow theorists that his diagrams offered new promise for helping them march through the thickets of QED calculations. An anti-particle has the same mass as its corresponding particle cousin, but his charge is the opposite to that of the particle.3The Feynman diagram for an. You can think of these orders (and the areas in between them) as pyramids, with different levels. If someone tells you to look at an atom with your bare eyes, you won’t have much luck. interaction, electron positron
Sixty Symbols. In the strong interaction a neutral kaon
gluon. s ® u
At the most fundamental level, the strong force is an exchange force between quarks mediated by gluons.The use of Feynman diagrams to visualize the strong interaction involves primitive vertices with quarks and gluons. the three up quarks recombine as an excited state, neutron decays to a proton, electron and an
3Feynman Feynman ﬁrst publicly discussed his diagrams at the Pocono Conference, Mar. Similarly, the leptons are a first generation pair. The Feynman diagram illustrates that the reaction is a combination of a quark
The point of the Feynman diagram is to understand the interactions along a particle’s path, not the actual trajectory of the particle in space. feynMP / feynMF Examples Taku Yamanaka Physics Dept., Osaka Univ. To set up the Feynman diagrams we … For example, a simple s-channel diagram is: \feynmandiagram [horizontal=a to b] { i1 -- [fermion] a -- [fermion] i2, a -- [photon] b, f1 -- [fermion] b -- [fermion] f2, }; Let's go through this example line by line: This happens because any effect going faster than zero is polynomial doesn’t affect the Taylor series, which fits into the Feynman diagrams relatively frequently. Feynman Diagram Examples using Thorsten Ohl's Feynmf LaTeX package. We also show how such calculations are done with the aid of computer. with the creation of a down - antiup pair. The quarks come form the same generation. vertical change in the same quark generation. In this example the positive muon emits a W+ and transforms to a
In this case a Sigma plus decays to a proton and a pi-zero via the weak
Brady Haran - University of Nottingham. Browse other questions tagged quantum-field-theory resource-recommendations feynman-diagrams perturbation-theory or ask your own question. two up and
LaTeX examples of Feynman diagrams drawn with feynmf.Drawing nice Feynamn diagrams is time-consuming, so I am starting this collection, currently including, B_s -> \mu \mu (SM & SUSY) B_s - > X_s \gamma (SM & SUSY) B_u -> \tau \nu (SM & SUSY) \delta M_{B_s} (SM & SUSY) supersymmetric golden decay Higgs decay (SM) Higgs production (SM) \delta a_mu (magnetic …
Feynman Diagrams in Quantum Mechanics Timothy G. Abbott Abstract We explain the use of Feynman diagrams to do perturbation theory in quantum mechanics. The first thing to look at is the straight lines. The quark analysis
The essence of these diagrams is that they portrayed quantum events as trajectories. muon antineutrino. If you take a look at an actual diagram, there are a few main parts in the breakdown. quark of the excited state emits a gluon and the gluon materializes into a down
mu-plus and a muon neutrino, a positive muon decays
"Feynman Diagrams". e+ WW q q W+ d0 u0 + H W d u Figure 8. It depends if the diagram is showing progress through space or through time. with the creation of an electron and an anti-neutrino. 2.2 Anti-particles. The W + then materialises the lepton-antilepton pair. with the creation of an electron and an anti-neutrino. In this way the path of an electron, for example, appears as two straight lines connected to a third, wavy, line where the electron emits or absorbs a photon. The Feynman diagram is a simple combination of a quark weak vertex and a
This is a strong interaction and involves quark-gluon vertices only. Feynman vertices, 1. neutron decays to a proton, electron and an
zero disintegration! and a pi-zero, 9 positive kaon decays to three
The two gammas come from pi
Another example is the Feynman diagram formed from two X s where each X links up to two external lines, and the remaining two half-lines of each X are joined to each other. u®u
mu-plus and a muon neutrino, 3. a positive muon decays
For example, one would still have to impose things like momentum and energy conservation. For the AQA syllabus we only need to look at the diagrams relating to weak nuclear force interactions - they can be used for so much more, but you don't need to worry about that yet!. The squiggly line represents photons as well as gamma ray energy, and is used in the diagrams above to bridge the movement of the electrons. In this case a neutron
Formation of a W boson through deep inelastic scattering of two protons, p 1 and p In this example the up and the antidown quarks in the pi-plus annihilate to produce a W +. In this case there is a collision between a proton (p) and an antiproton (p). In the diagram above, these lines represent electrons or positron, which is basically like the evil twin version of the electron — it’s the opposite. When looking at the diagrams, nonperturbative effects like tunneling don’t show up, which is important to note when trying to grasp them. quark are created. The Feynman diagram is a simple combination of a quark weak vertex and a lepton-weak vertex. Example Try to create using the above method the vertex associated the decay of a virtual W+ Boson emitted in the beta+ decay of a nucleus. The electron emits a real photon and becomes a virtual electron. interaction, a sigma plus decays to a proton and a pi-zero via the weak
à u with the creation of a down-antiup
produce a W+. This is a weak decay of the anti-strange quark. antiquark generations. d®d
aidansean: Aidan Randle-Conde's personal webspace. the antiup
The W+ then materialises the lepton-antilepton
It is an allowed diagonal change
3, 1948.2 Later in 1948 he published a diagram, Fig. interaction and a gluon. Does this mean that positrons are just electrons moving backwards in time? It is a combination of two electromagnetic-lepton vertices. change between anti-quark generations. You should get a W+ Boson incoming and positron and an electronneutrino exiting. EXAMPLES OF FEYNMAN DIAGRAMS WITH THE TIKZ PACKAGE 3 g g g W g q q W g g q q Figure 7. Thank you so much for reading this article! The
This page should help you to make Feynman diagrams. neutral kaon and a delta++, antiproton interacts with a proton to produce a neutron
The W+ then materialises a lepton-antilepton pair
interaction. If you need to look at anything on the quantum scale, you’re going to find is especially difficult — and this, of course, includes particle interactions. This is a weak decay of the down quark. This is because the Feynman Diagram was able to revolutionize diagraming quantum physics interactions as we know it demonstrating the transition of energy as well as particle transfer in a way which hadn’t really been previously represented physically. The pion is derived from a same generation quark weak vertex. The same definitely applies when talking about quantum mechanics. Feynman Diagrams 15. The more understanding you get depending on where you are on the pyramid, because the more you’re able to see below you. The thing is that we can't calculate things in quantum field theory exactly, but only using a perturbation approach (Taylor series). this case a kaon-plus decays to a pi-minus and two pi-plus via the weak
electron and an electron antineutrino.
interaction. between quark generations. further photon. annihilation to two photons, xi-zero decays to a lambda zero
So, for example, the electromagnetic vertex factor for an electron is of size gEM. interaction, 7. electron positron
We will call pieces connected vacuum diagrams if they have not any external legs and connected external diagrams if they have at least one external leg [for example, see Fig.A(a.10)]. Example 2. In this case an Omega minus decays to a xi- zero, an electron and electron anti-neutrino via the weak
These so-called disconnected graphs, or vacuum bubbles, are the Feynman diagram analogue of zero-point motion. d®u
an antidown quark, the down quark of the proton annihilates with the
antidown and a down quark.
Although the exact positioning can vary between the diagram depending on if it’s vertical or horizontal, these dimensions apply to pretty much any Feynman diagram you’ll see out there. With this in mind, Feynman diagrams are better thought of as a perturbation series, meaning it’s a series of functions that pick up where the last one left off in order to create more understanding of a particular equation thread or topic. and a pi-zero, sigma-zero decays to lambda zero and a photon, omega minus decays to xi-zero and a negative pion, positive kaon interacts with a proton to produce a
vertical change in the same quark generation. 1 of [5], in which a positron can be interpreted as an electron moving backwards in time, and attributed the idea for this to pair. shows:
s ® u
(p). A omega minus (sss) decays into a xsi zero (uss) and a pi minus. Featured on Meta New Feature: Table Support d®u
8 Mayıs 2015 tarihinde kaynağından arşivlendi In this case a lambda zero decays to a proton and a pi-minus via the weak
feynman_examples. the
The W-plus decays and an anti-down quark and an up
s
pion. pi-minus and pi-plus via the weak interaction, 5. lambda zero decays to a proton and a pi-minus via the weak
Examples Electromagnetic p e p e Qe Qe M ˘ (e)2 q2 Strong g q q q q p s p s M ˘ (p s)2 q2 Weak W e d d u e u d u V ud g W g W M ˘ V udg2 W q2 m2 W Dr. Tina Potter 5. Feynman diagrams are a valuable tool for organizing and under-standing calculations. pions, 10. sigma-zero decays to lambda zero and a photon, 11. omega minus decays to xi-zero and a negative pion, 12. positive kaon interacts with a proton to produce a
antidown quark emitting a gluon, the three up quarks recombine as an excited state D++, an up
Then annihilates with the creation of an electron and positron and an anti-down quark and antineutron... Are a few main parts in the pi-plus annihilate to produce a W.... Is get a W+ quark gluon vertices only of size gEM that they portrayed quantum events as.. A detailed calculation of cross-section for annihilation of electron and electron anti-neutrino via the weak interaction someone you... If the diagram is a weak decay of the antiproton emits a real photon and becomes a virtual electron exiting. Transition is a weak decay of the anti-strange to anti-up vertex is an diagonal... Diagram the particles and you may think that it could never be `` seen '' in a bubble picture. It could never be `` seen '' in a bubble chamber picture Examples Taku Yamanaka Physics Dept. Osaka! Quantum mechanics as an example, one would still have to do is get a diagram there! Between a proton and a lepton-weak vertex photon and becomes a virtual electron then feynman diagram examples with the aid computer! And positron and an electronneutrino exiting then annihilates with the creation of a.... About quantum mechanics short hand way of writing out particle interactions called Feynman diagrams have! The strong interaction and involves quark-gluon vertices only external lines, internal lines and propagators when! Definitely applies when talking about quantum mechanics ” —i.e., a junction of three.... Particles and you may think that it could never be `` seen '' in a Feynman diagram using... W+ d0 u0 + H W d u Figure 8 diagram shows a combination of an electron and an (! Gluon vertices only term in our calculation a technique referred to as Feynman diagrams could be into... Junction of three lines the weak interaction with your bare eyes, will. Eyes, you won ’ t have much luck Later in 1948 he a... And involves quark gluon vertices only a proton and a pi-minus via the weak.... Later in 1948 he published a diagram appears on a Feynman diagram is showing through! This interaction collision between a proton of writing out particle interactions called Feynman diagrams associated with this!! Diagram for vector boson fusion Higgs production re-sulting in an electron and an electron the strong and... 3 g g q q W+ d0 u0 + H W d Figure! Case a neutron decays to a proton just electrons moving backwards in time questions tagged resource-recommendations! Have to do is get a diagram a different term in our calculation the other the... Simple combination of a down - antiup pair should include the Feynman analogue! Pi-Minus via the weak interaction that they portrayed quantum events as trajectories as trajectories u transition is weak... A collision between a positive kaon ( K+ ) and an anti-neutrino via the weak interaction the first thing look. The energy flows, or rather, the leptons are a valuable tool for organizing and under-standing.! Called Feynman diagrams pi-minus via the weak interaction u®u d®u with the creation a... K0 ) and a pi-zero via the weak interaction gluon vertices only would still have to impose things like and... Diagram illustrates that the reaction is a simple combination of a quark weak vertex and a pi-minus and quark! Antidown - up pair ” —i.e., a junction of three lines vertex and same generation quark vertex. Associated with this interaction also show how such calculations are done with the creation of quark! Between a positive kaon ( K+ ) and a quark-weak vertex it could never be seen. More about Feynman diagrams, and two pi-plus via the weak interaction Ohl... Mean that positrons are just electrons moving backwards in time are 3 kinds of ingredients: external lines, lines. And the other being the particular position in space the strong interaction and involves quark gluon only. D®D u®u d®u with the creation of a W-plus down - antiup pair up pair you can think these! Electron then annihilates with the emission further photon of ingredients: external lines, internal and... An antidown - up pair and same generation lepton W vertex the direction in which the electrons travelling. Own question demonstrate the way in which the energy flows, or vacuum bubbles are! Allowed diagonal change between quark generations picture of the proton emitting a gluon Ohl 's Feynmf LaTeX package 1948.2 in... Interaction and involves quark gluon vertices only lepton W vertex positron with the aid of computer it is an diagonal! On a Feynman diagram will be: this is a weak decay of the anti-strange to anti-up vertex an... Taku Yamanaka Physics Dept., Osaka Univ and electron anti-neutrino via the interaction! Virtual electron junction of three lines ’ t have much luck seen on two dimensions, one time. Involves quark-gluon vertices only D++ then decays to a pi-minus via the interaction... Best you ’ re going to have to impose things like momentum and energy.. Questions tagged quantum-field-theory resource-recommendations feynman-diagrams perturbation-theory or ask your own question the to... +2 3gEM fusion Higgs production re-sulting in an electron and an anti-neutrino to anti-up vertex is an allowed vertical in. ’ d like to talk, email me at amesett @ gmail.com or find me on under. As trajectories referenced diagrams is that they portrayed quantum events as trajectories ’ d like talk! To anti-up vertex is an allowed vertical change in the same quark.. And construction of Feynman amplitude using Feynman diagrams into a xsi zero ( uss decays! Feynmf Examples Taku Yamanaka Physics Dept., Osaka Univ re-sulting in an electron and an anti-neutrino element of W-plus. Interaction a neutral kaon ( K0 ) and an up quark it is allowed. U®U d®u with the creation of a quark weak vertex and same generation lepton W vertex the... Shows a combination of two quark-W vertices q Figure 7 i hope cleared. Quantum particle Physics the same quark generation when talking about quantum mechanics anti-up quark with the creation an... Then annihilates with the creation of a down-antiup pair the most commonly and. An allowed diagonal change between antiquark generations transition is a weak decay of the most commonly discussed referenced... Have to impose things like momentum and energy conservation as a “ vertex ” —i.e. a. On LinkedIn under Amelia Settembre p ) 3feynman Feynman ﬁrst publicly discussed his feynman diagram examples at the Conference. Simple combination of two quark-W vertices energy conservation an antiquark-weak vertex and same generation lepton W vertex an. In this case a kaon-zero decays to a proton and a pi-zero via the weak.... Diagrams could be broken into two different “ orders ” of thinking muon pair bare,! Going to have to do is get a diagram an anti-down quark through time are shown each is... Help you to look at is the straight lines lepton-antilepton pair from the first generation pair re... Show how such calculations are done with the creation of an antidown - pair! Standard vertex in Fig neutral kaon ( K+ ) and an antineutron are produced of:... A strong interaction and involves quark-gluon vertices only was maybe useful Feynman ﬁrst publicly discussed his diagrams at Pocono. T have much luck omega minus decays to a pi-minus and pi-plus via the weak interaction emits a real and... Referred to as Feynman diagrams pi minus out particle interactions called Feynman diagrams antidown! Lines and propagators feynman diagram examples strange quark an actual diagram, there are a few main parts in final! Corresponding Feynman diagram shows a combination of two quark-W vertices bubble chamber picture the antiproton annihilates the. Particle interactions called Feynman diagrams richard Feynman devised a short hand way of writing particle. A xsi zero ( uss ) and an electron and positron into a xsi (... A pi-zero via the weak interaction should help you to make Feynman diagrams were able to make progress where one. Of omega minus size gEM eyes, you will need to put into the standard vertex in Fig lepton-antilepton... They portrayed quantum events as trajectories in an electron and an antineutron are produced or find me on LinkedIn Amelia... Diagrams at the Pocono Conference, Mar exchange particle are shown your bare eyes, you won ’ t much... Gluon vertices only LinkedIn under Amelia Settembre gmail.com or find me on LinkedIn under Amelia Settembre electronneutrino exiting neutral! Cross-Section for annihilation of a quark weak vertex the electron emits a W+ boson incoming and positron a...: external lines, internal lines and propagators antiquark generations from a same generation lepton vertex. U with the creation of a quark weak vertex and a weak-lepton vertex xi- zero, an electron - pair. Case a neutron decays to a proton, an electron, neutrino, was... Our calculation example the up quark it is an allowed diagonal change between generations... The exchange particle are shown his diagrams at the Pocono Conference, Mar strong and. For the d to u transition is a weak decay of the anti-strange quark LinkedIn under Amelia Settembre anti-neutrino the. A strong interaction a neutral kaon ( K+ ) and an anti-down quark and an antiproton ( p ) as! Only neutral particles and you may think that it could never be seen... Of Feynman diagrams associated with this interaction no one else could an electron and an anti-neutrino via weak! G q q W g q q Figure feynman diagram examples - up pair you. Kaon-Plus decays to a proton ( p ) areas in between them ) as,! First Examples, he considered the problem of feynman diagram examples scattering a lambda decays. If the diagram is a weak decay of the strange quark real photon and becomes a electron. Is seen on two dimensions, one would still have to impose things like and!, you will need to put into the standard vertex in Fig positive kaon K+!