What is Particle physics: Definition and 531 Discussions

Particle physics (also known as high energy physics) is a branch of physics that studies the nature of the particles that constitute matter and radiation. Although the word particle can refer to various types of very small objects (e.g. protons, gas particles, or even household dust), particle physics usually investigates the irreducibly smallest detectable particles and the fundamental interactions necessary to explain their behaviour.
In current understanding, these elementary particles are excitations of the quantum fields that also govern their interactions. The currently dominant theory explaining these fundamental particles and fields, along with their dynamics, is called the Standard Model. Thus, modern particle physics generally investigates the Standard Model and its various possible extensions, e.g. to the newest "known" particle, the Higgs boson, or even to the oldest known force field, gravity.

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  1. D

    Particle collisions - a question on angles relative to beam

    Consider the case in which an incoming particle collides with stationary target particle producing new particles through the interaction. For example, $$e^{-}+e^{+}\rightarrow X+\bar{X}$$ My question is, why in general do the particles produced in such an interaction propagate outwards are...
  2. A

    Teaching particle physics in basic education

    Hi guys! I'm doing a research about teaching elementary particles in the middle school, something that isn't the reality in my country. Despite of the research in Physics Teaching be a lot advanced, the proposals made by them are not applied in the practice of the teachers. I want to propose...
  3. It's me

    Using Noether's Theorem find a continuity equation for KG

    Homework Statement Consider the Klein-Gordon equation ##(\partial_\mu \partial^{\mu}+m^2)\varphi(x)=0##. Using Noether's theorem, find a continuity equation of the form ##\partial_\mu j^{\mu}=0##. Homework Equations ##(\partial_\mu \partial^{\mu}+m^2)\varphi(x)=0## The Attempt at a Solution...
  4. A

    I Is the SM of particles physics and Cosmology SM

    I'm in a deep discussion with a friend. He says that the Standard Model of particle physics is actually known by Standard Model of cosmology and that both are the same and that the SM of particle physics is in the Minkousky geometry... I disagree about this, I do think that the SM of particle...
  5. C

    A Do cosmologists take spontaneous symmetry breaking seriously?

    I suppose that my questions are pretty basic, but I've been trying to find out the answers and not succeeded. 1.- Do cosmologists really think that the vacuum state suddenly changed in the early Universe? If so, would it be like a phase transition? If so, first or second orther? 2.- Does the...
  6. S

    Lie algebra for particle physics

    Hello! I am sorry that this questions is not actually directly related to physics, but, can anyone recommend me a good book about abstract algebra (basically lie algebra, representation theory etc.) used in physics? I have tried for a long time to find something online but I haven't find a...
  7. mfb

    Insights LHC Part 4: Searching for New Particles and Decays - Comments

    mfb submitted a new PF Insights post LHC Part 4: Searching for New Particles and Decays Continue reading the Original PF Insights Post.
  8. J

    I Unraveling Representations of SU2 & SU3 in Particle Physics

    Hi, I'm recently reading some text on particle physics and there is a section on symmetries and group theory. It gave the definition of SU2 as the group of unitary 2*2 matrices and that SU3 is the group of unitary 3*3 matrices. However, it kind of confuses me when it mentioned representations...
  9. Basicsofphysics

    A A Unified Theory of Relativity and Particle Physics

    Is there a peer reviewed paper that proposes a way to connect the relativity of time dilation, length contraction and the relative effects of gravitation per acceleration with respect to mass with the standard model of particle physics? An established theory which also takes into account both...
  10. J

    What is the Concept of Singularity in Relation to Black Holes?

    I'm looking for help in understanding the meaning, nature and/or concept of singularity as such applies to the mechanics of a black hole ...
  11. I

    I Is this Linear Accelerator Design Valid?

    Good Evening Everyone, A group of friends and I were having a mini-contest, to see who could theoretically make anti-matter using the most simplistic design in terms of cost and general complexity. The obvious choice for us was the Positron, due to low energy requirements on all fronts. One of...
  12. P

    What Is the Role of Color Charge in Strong Interactions?

    Homework Statement In electromagnetic interactions, the force carrier is the photon, and it interacts with anything which has electric charge. Electric charge can be represented by the integers on a single number line and photons themselves carry no electric charge. (a) In the case of the...
  13. S

    I S-Channel Process: a+b->c+d Diagrams

    Hello I encountered a problem in which it is specify that there are 2 time-ordered diagram for the s-channel for a certain process a+b->c+d. I understand that there is the one that can be associated with annihilation, but what would be a second one? Thank you!
  14. Andreol263

    Quantum Gauge Theories on Particle Physics

    Well, I'm planning to learn from this book when i finish Shankar's Principles of Quantum Mechanics, if it fulfills the requiriments in this part, but from where i can learn the Special Relativity necessary to tackle this book?
  15. Xico Sim

    I Method to know if a reaction is allowed

    Hi guys. This is my first post here. Here it goes. I'm attending an introductory course on particle physics. By now, I'm supposed to know how to find out if a given reaction, say νμ+p→μ++n (for example) is possible or not. Unfortunately, the rules by which a reaction must abide are still foggy...
  16. Junii1

    Physics Australia and particle physics

    Hey! I am a year 11 student from Australia and I am wanting to take course(s) in particle physics at university/college after high school. I am just wondering where I can do this as I haven't found many universities (In Victoria) that offer this. If anyone has experience from overseas I would...
  17. C

    Prereqs for learning particle physics?

    I want to start studying particle physics on my own and wanted to know what the prerequisite are? I'm in my second year of college and have finished Calc. 3 and Physics with calc. 3. I'd also be interested in textbook recommendations.
  18. Matt atkinson

    What is the maximum recoil energy of photons in Inverse Compton Scattering?

    Hello all, I'm just doing some practice for an upcoming exam and came upon this question in my notes: One experimental way to generate very high energy photons is to ”collide” a laser beam against an electron beam, the photons that recoil in the direction parallel to the electron beam will have...
  19. itssilva

    A Torsion forms and particle physics

    Hi; I've been doing some research for my master's on gauge theory in the language of fiber bundles, and something occurred to me. Both GR and the Standard Model (SM) can be described in terms of connections (potentials) and curvatures (field strengths), but there's this generalization of GR...
  20. luke179

    Physics Changing from humanities to physics -- help needed

    Hello all. This is my first thread. I am 23y/o male. After my high school I wanted to go for physics but due to family pressure I went for marine engineering but bailed out after two years as I find it boring and unappealing. After that I tried two and half year for a government job but lost...
  21. P

    Momentum density of states for pion decay.

    Homework Statement I am trying to calculate the ratio of the density of states factor, ##\rho(p)##, for the two decays: $$\pi^+\rightarrow e^++\nu_e~~$$ and $$\pi^+\rightarrow \mu^++\nu_{\mu}~~$$ Homework Equations ##\rho(p)~dp=\frac{V}{(2\pi\hbar)^3}p^2~dp~d\Omega## Which is the number...
  22. Schwarzschild90

    Particle physics exam preparation

    Homework Statement See the PDF. I would like some pointers as to what would be most relevant to talk about Homework Equations Amplitude, cross sections and decay rates. The Attempt at a Solution 1) Particle classification: From the Eightfold way to the quark model[/B] Particles are...
  23. T

    Particle physics basic concept from Standford Uni help

    Let's start with a vacuum, I will write |0000...> as |0>. $$ \psi^+ (x) |0\rangle = \sum_k e^{-ikx} a^+ (k) |0\rangle $$ Qns: What happens if you superpose/add up state vectors corresponding to a particle of momentum k and you add up with coefficient e-ikx? $$ \sum_k e^{-ikx} a^+ (k) |0\rangle...
  24. P

    Feynman diagram; ##\pi^0+\pi^0\rightarrow \pi^++\pi^-##

    Homework Statement For the reaction below draw three Feynman diagrams, one that proceeds through exchange of a gluon, one through a photon and one exchanging a weak W-Boson. ##\pi^0+\pi^0\rightarrow \pi^++\pi^-## Which diagram provides the dominant contribution for this reaction? Explain how...
  25. L

    What is the wavelength of an electron of 5eV energy?

    Homework Statement Calculate the wavelength of an electron which has 5eV of energy.Homework Equations de Broglie's equation: lambda=h/p , kinetic energy equation: K=0.5mv^2 The Attempt at a Solution My attempt: I figured out that using de Broglie's wavelength equation was necessary for this...
  26. M

    Undergraduate Senior Physics Research Topic (Theory)

    Hello all, This is most likely a question for those who have experience/knowledge of theoretical/mathematical physics at the graduate level and can provide recommendations following my criteria. Here is some background about me: I am a senior majoring in math and physics at a small...
  27. J

    Particles with electric charges visible to the human eye?

    Are there any particles known in the Physics world with an either positive or negative charge that can be viewed by the human eye under LED light illumination and have an attraction/repulsion to magnetism?
  28. C

    How did a 49-year-old electrical engineer become fascinated with QED and QFT?

    I am a 49 years old electrical engineer who lectures Optical Communications at the University of Seville. I learned QED because I wanted to understand the ground principles of my area of expertise. I was amazed and thrilled by the beauty of QFT, so I decided to keep on studying. Fearly recently...
  29. C

    Can electro-weak unification be tested at CERN?

    1.- Electroweak interaction broke its symmetry about 1ps after the Big Bang and two different types of interactions appeared: weak interactions and electrodynamics. 2.- The LHC at Geneva is routinely conducting experiments above the energy threshold of electroweak unification. Could these...
  30. S

    Ranking of a set of theoretical particle physics programs

    Among the following programs, which are the best for theoretical particle physics? Stony Brook, Penn State, Iowa State, Urbana Champaign, Arizona, Arizona State, Georgia Tech, Florida, Tennesse KnoxVille Are there some other programs of lower ranking in the league tables, but has a strong high...
  31. P

    Undergraduate Math for Quantum Optics vs Particle Physics

    I'm halfway through my junior year and I'm hoping to do Quantum Optics or Particle Physics in graduate school (I'm doing the recommended courses for both since I'm still undecided). Besides the math required from the physics major (ie. Calculus, linear algebra, ODEs, PDEs, complex analysis)...
  32. DeathbyGreen

    PhD Field Selection: Tips & Advice

    Hello, So before I start, I realize that this question has been asked in the past, but all of the threads were over several years old so I'm not sure if the information is still current. I've been thinking about this decision for a while: I'm currently in my second year at a respected...
  33. Wesley Strik

    What Magnetic Field Strength Is Needed to Keep Protons at 7 TeV in the LHC?

    Homework Statement Estimate the magnetic field required to maintain protons at 7TeV in the LHC at CERN. The LHC has a circumference of 27 km. State any assumptions or approximations you make. Homework Equations lorentz force, assuming magnetic field is always perpendicular to the direction of...
  34. J

    Speed of an antimuon in a pi meson decay

    Homework Statement I'm trying to confirm the speed of an antimuon in the \pi^+ \rightarrow \mu^+ \nu_{\mu} decay through the laws of conservation but it doesn't add up. Homework Equations [/B] 1.Energy-momentum relation: E^2 = (pc)^2 + (mc^2)^2 2. Rest masses: m_{\pi} = 139.6 \...
  35. B

    Thomson, Modern Particle Physics, Problem 6.7

    In Mark Thomson's Modern Particle Physics, Problem 6.7, I am wondering how we obtain: 2(ms, 0, 0, 0) and -2(ms, 0, 0, 0) for the RL and LR helicities (likewise for the muon) in the electron currents using helicity combinations. My solutions for the other helicities (RR, LL) work out, but I am...
  36. T

    Mathematical modeling in particle physics

    So my university offers two programs focused on particle physics. One is simply masters in nuclear/particle physics, the other is masters in mathematical modelling with focus on particle physics. I want to go into mathematical modelling and I'm choosing what I will focus on. I'm not really...
  37. erbilsilik

    Theoretical Particle Physics or Medical Physics?

    Hi everyone! I'm a newbie in this forum. And I need your help for making the right career path for my future. I've been graduated from Physics three months ago and I took some exams (like TOEFL and GRE) for applying master's degrees programs in Turkey. I'm from Kosovo and Kosovo is a developing...
  38. A

    Particle Physics: Net Force on Charge q1 Calculation

    Homework Statement Three point charges are located on the positive x-axis of a coordinate system. Charge q1 = 2.0 nC is 2.0 cm from the origin, charge q2 = -3.5 nC is 4.0 cm from the origin and charge q3 = 5.0 nC located at the origin. What is the net force ((a)magnitude and (b) direction) on...
  39. F

    4 momentum is particle physics

    Okay so i have a question for you guys if I have a positron striking an electron at rest to create 2 pions( + and -) and I want to calculate the minimum kinnetic energy that the electrons can possesses to create these pions... then the created pions will be at rest correct? so this gives me two...
  40. Allen Beers

    Programs Particle Physics Degree: Schools Offering Degree

    Does anyone know of any schools that offer degrees specifically in particle physics?
  41. Dilatino

    Introduction to Young-tableaux and weight diagrams?

    I am looking for a short pedagogical introduction to Young-tableaux and weight diagrams and the relationship between them, which contains many detailled and worked out examples of how these methods are applied in physics, such as in the context of the standard model and beyond for example. I am...
  42. Dilatino

    Confused about isospin conservation in rho to pion decays

    The decay \rho^0 \rightarrow \pi^- \pi^+ occurs with a probability of 100\%, whereas the decay \rho^0 \rightarrow \pi^0 \pi^0 does not occur in nature, due to isosphin conservation. I don't understand this. Looking at the Isospin and its third component ¦I,I_3\rangle we have in the first...
  43. ShayanJ

    Topological effects in Particle Physics

    I've been checking a university's descriptions of its research groups and their interests, where I encountered the phrase "Topological effects in Particle Physics" which had no explanation. I searched in the internet, but I couldn't find anything. Could anyone explain about such effects and...
  44. Moelf

    Schools Choice for particle physics between LAC and university

    Hi guys, I don't know if there's any similar thread (I didn't find any, but in case I missed it); if so please suggest them to me. It's time to apply to college again. I personally think particle physics (experimental) would be my top choice (I understand that only phd has the specialized...
  45. Quandemonitum

    Mathematical proof of the spherical electron?

    Why is/are an electron/electrons a sphere/spheres ? Need the mathematical proof...
  46. Quandemonitum

    What is the wave function for the whole system/atom ?

    For example, let's say that psi(q) is the wave function of an electron(which describes/represents the electron) that is located in an atom and isolated/unentangled from the rest of the system. What is the wave function value of this psi(q) ? What is the wave function for that whole atom(with...
  47. Christian Grey

    Which theory or field can explain this?

    Suppose I am in a room and light(photons) from the light bulb reach my eyes, or I am outside light(photons) from the sun reach my eyes and I am able to see the objects around me. I want to know what factors affect the path of photons like temperature, gravity etc.I mean by knowing these factors...
  48. M

    Naming of the Leptons - Find the Right Word

    Hi, I am currently an undergraduate student and I am writing my undergraduate research paper right now. The thesis is about searching for heavy Majorana type neutrinos. While writing the paper, I really need some 'right word' but I can't find it so let me explain it here, and it would be very...
  49. U

    What is the expected rate of reactions in the detector?

    Homework Statement A reactor fires out ##10^{21}## neutrinos per second. A detector containing ##10m^3## of liquid which contains 30 carbon atoms every 60 hydrogen atoms. The detector-reactor distance is ##1000##. The cross section for the reaction is ##\sigma = 10^{-46} m^2##, and the density...
  50. U

    Experiments to distinguish 3-body and 2-body decays?

    I was wondering are there any experiments to distinguish between 2 and 3-body decays? For example, consider decay of the muon and the pion: The pion only emits 1 muon neutrino ("missing energy") and 1 muon. The muon however, emits 1 muon neutrino, 1 electron neutrino and 1 electron. How is...
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