Differences

This shows you the differences between two versions of the page.

--- models:standard_model [2018/03/30 14:09]
jakobadmin [Concrete]
+++ models:standard_model [2019/07/03 08:12] (current)
jakobadmin [FAQ]
@@ Line 3: / Line 3: @@
 </WRAP>
-====== The Standard Model ======
+====== Standard Model of Particle Physics ======
@@ Line 18: / Line 18: @@
 **Particle Content**
-{{ :models:standardmodel.png?nolink&400 |}}
+{{ :models:paper.journal.40.png?nolink&800 |}}
 ----
@@ Line 29: / Line 31: @@
 <tabbox Concrete>
---> Particle Content#
+At the heart of the Standard Model is the [[advanced_tools:gauge_symmetry|gauge symmetry]]
+$$
+G\ =\ SU(3)_C\times SU(2)_L\times U(1)_Y\, .
+$$
+The $SU(3)_C$ mixes the three colors of the quarks and antiquarks,
+the $SU(2)_L$ the weak isospin, and the $U(1)_Y$
+couples to the weak hypercharge $Y$.
-  * {{ :models:sm-overview.pdf |The field content of the standard model is nicely summarized here}}
+The electroweak symmetry $SU(2)_W\times U(1)_Y$
+is spontaneously broken by the scalar field $\langle H \rangle \neq0$ down to $U(1)_{EM}$.
+As a result, the $W^\pm$ and $Z^0$ vector particles become
+massive ($M_W\approx80.4$ GeV, $M_Z\approx91.2$ GeV) while the
+photon $\gamma$ remains massless.
-<--
+----
@@ Line 46: / Line 59: @@
+<--
+-->Particle Content#
+{{ :models:sm-overview.pdf |The field content of the standard model is nicely summarized here}}
+**The Gauge Bosons**
+The __photon__ couples to the electric charge which is a linear combination of hypercharge and weak isospin
+$$
+q\ =\ T^3\ +\ Y .
+$$
+The photon is responsible for electromagnetic interactions. Since it is massless the electromagnetic forces are long-ranged.
+The __$W^\pm$ and $Z^0$ bosons__ are responsible for the weak interactions. Since both are massive the weak force is short-ranged.
+The bosons responsible for the strong force are called __gluons__. This name stems from the fact that they ``glue'' the quarks and antiquarks together. Bound states made of quarks and antiquarks are called baryons and mesons.  The strong forces become stronger with rising distance between two color-chared particles. As a result individual quarks, antiquarks, or gluons can't be isolated. This is known as confinement. Only $SU(3)_C$ singlets can be observed.
+----
+**The Fermions**
+All __quarks__ come in 3 colors $c=1,2,3$ and 6 additionally six flavors $f=u,d,s,c,b,t$
+called `up', `down', `strange', `charm', `bottom', and `top'.
+The left-handed quarks form 9 $SU(2)_L$ doublets:
+$$(u,d)_L, (c,s)_L, (t,b)_L$$
+(3 for each color)
+The right-handed quarks are $SU(2)_L$ singlets.
+This curious difference between left-handed and right-handed quarks means that weak interactions disrespect the parity symmetry. The bosons $W^\pm$ only couple to the left currents $J^\mu_L=V^\mu-A^\mu$
+and don't care about the right currents $J^\mu_R=V^\mu+A^\mu$.
+The same is true for the __leptons__ $e^-$, $\mu^-$, $\tau^-$, and the 3 neutrino species.
+The left-handed leptons live in three $SU(2)_L$ doublets:
+$$(\nu_e,e^e)_L, (\nu_\mu,\mu^-)_L, (\nu_\tau,\tau^-)_L$$.
+The right-handed charged leptons $e^-_R$, $\mu^-_R$, $\tau^-_R$
+are $SU(2)_L$ singlets. So far right-handed neutrinos were never observed.
+<--
+-->Standard Model Interactions#
+[{{ :models:586px-standard_model_feynman_diagram_vertices.png?nolink |Source: Image by Garyzx published under the [[https://creativecommons.org/licenses/by-sa/3.0|CC BY-SA 3.0]] licence}}]
 <--
 ----
@@ Line 129: / Line 191: @@
 <cite>http://math.ucr.edu/home/baez/week253.html</cite>
 </blockquote>
+<blockquote>r. Correlation functions of local operators in
+R1,3 depend only on the Lie algebra of the gauge group and are unaffected by global
+issues such as the choice of Γ. This means that no current experiment can distinguish
+between the four possibilities. Nonetheless, the physics in flat space can depend in
+subtle ways on Γ (and in more dramatic ways when spacetime has interesting topology).
+The purpose of this paper is to describe the crudest differences between the theories:
+the spectrum of line operators and the periodicities of theta angles.<cite>https://arxiv.org/pdf/1705.01853.pdf</cite></blockquote>
 **A great discussion of these things with awesome illustrations can be found in section 1.4 and at page 26 in Some Elementary Gauge Theory Concepts by Hong-Mo Chan, Sheung Tsun Tsou:**
@@ Line 197: / Line 267: @@
 <--
---> Questions left open by the standard model?#
+--> What questions are left open by the standard model?#
 See [[:open_problems|Open Problems]]
+<--
+--> What symmetries do exist in the standard model and what is their experimental status?#
+see https://physics.stackexchange.com/questions/97896/symmetries-of-the-standard-model-exact-anomalous-spontaneously-broken
 <--
 <tabbox History>
   * The Rise of the Standard Model: A History of Particle Physics from 1964 to 1979 by Lillian Hoddeson
   * Resource Letter: The Standard Model and Beyond by Jonathan L. Rosner
+  * https://inference-review.com/article/the-standard-model by Sheldon Glashow
 </tabbox>

User Tools

Site Tools

Differences

Page Tools