Classification of elementary particles
Classification of Mesons
Classification of Leptons
Classification of Nucleons
Classification of Hyperons
Particle Physics Previous Years Questions
State the quantum numbers $I_z$, $Y$ and $S$ for the uds quarks and antiquarks. Which combination of these leads to the formation of (i) proton and (ii) neutron? $\\$ [10 Marks][2010,2013, 2015]
Explain conservation of Baryon Number. Comment on the stability of proton. $\\$ [10 Marks][2011]
Which of the following reactions are permitted or forbidden by various conservation laws?
$k^-+p\rightarrow\Lambda^\circ+\pi^\circ$
$k^++n\rightarrow\Sigma^++π°$
$\pi^-+p\rightarrow k^-+\Sigma^+$
$\pi^++n\rightarrow k^++Λ°$
$\pi^-+p\rightarrow\Lambda^\circ+k^\circ$
$\pi^-+p\rightarrow k^++\Sigma^-$ $\\$ [12 Marks][2012]
In the following reactions indicate with an explanation, whether they proceed by strong, electromagnetic or weak interaction or they are forbidden:
$\pi^+\rightarrow\mu^++v_\mu$
$p\rightarrow n+e^++v_e$
$p+\pi^-\rightarrow K^++\Sigma^-$ $\\$ [15 Marks][2013]
How are elementary particles classified on the basis of their participation in fundamental interaction? $\\$ [10 Marks][2014]
Describe grand unification theories (GUT). $\\$ [20 Marks][2015]
How many types of neutrinos exist? How do they differ in their masses? $\\$ [15 Marks][2015,2021]
Write down the following decays in terms of quarks:
$\Omega^- \rightarrow \land^0+K^-$
$\land^\circ \rightarrow p+\pi^-$
$ K^{-} \rightarrow \mu^{-} + v_{\mu} $ $\\$ [15 Marks][2015]
What are elementary particles and how are they classified? Describe in brief the different types of interactions that can occur between the elementary particles. $\\$ [6+4 Marks][2016]
Explain the various leptonic family members. What is leptonic number conservation? Based on this conservation law, state whether the following reactions are possible or not:
$\pi^- \rightarrow \mu^-+ \bar{v_τ}$
$n \rightarrow p^++e^-+ \bar{v_e}$ $\\$ [10+5+5+5 Marks][2016]
Write down the quark structure of the following hadrons: $\Delta^{++},\Omega^-,\Sigma^-\mathrm{and\ }\land^\circ$ $\\$ [6 Marks][2016]
Write down the following decays in terms of quarks:
$n \rightarrow p^++e^-+ \bar{v_e}$
$\Delta^+ \rightarrow \pi^++n$
$\Sigma^+ \rightarrow p^++\pi^0$ $\\$ [9 Marks][2016]
Explain unification of electromagnetic and weak interactions. What is $Z^\circ$ - boson? What is its relevance in electroweak unification? $\\$ [10 Marks][2016]
State the three characteristic properties of strong, weak and electromagnetic forces distinguishing one from the other. $\\$ [5 Marks][2017]
Point out the interactions in which the following conservation laws are obeyed or violated $\\$ (a) Isotopic spin $\\$ (b) Hyper charge $\\$ (c) Lepton number $\\$ (d) Charge conjugation $\\$ [10 Marks][2017]
Write down the quark constituents of each of the following:
$\pi^+$
$K^+$
$\Delta^{++}$
$\Sigma^\circ$
$\Omega^-$ $\\$ [5 Marks][2017
Which of the following elementary particle reactions/decays are allowed under various conservation laws? If allowed, write down the type of interaction and the characteristic time by which it would proceed :
$p+n\rightarrow\Lambda^0+\Sigma^+$
$\pi^++n\rightarrow\Lambda^0+K^+$
$p+n\rightarrow K^++\Sigma^+$
$\pi^0\rightarrow\gamma+\gamma$
$n \rightarrow p^++e^-+ \bar{v_e} $ $\\$ [10 Marks][2018]
Write down the basic weak interaction processes in the nuclei. Also illustrate the beta decays of $\\$ (i) neutron $\\$ (ii) proton. $\\$ [15 Marks][2020]
List in two separate columns, the quantities that are conserved and not conserved in the weak interaction of particles. $\\$ [10 Marks][2020]
$\rho^\circ$ and $K^\circ$ mesons both decay mostly to $\pi^+$ and $\pi^-$. Explain why the mean lifetime of $\rho^\circ$ is shorter $\left(\backsim{10}^{-23}\mathrm{\ } s\right)$ compared to the mean lifetime of $K^\circ\left(\backsim{10}^{-10}\mathrm{\ } s\right)$. $\\$ [10 Marks][2021]
What are the properties of the particles made up of the following quarks? $\\$ (a) ud $\\$ (b) ud $\\$ (c) dds $\\$ (d) uss $\\$ $\\$ [10 Marks][2021]
Explain why each of the following particles cannot exist according to the quark model. $\\$ A Baryon of spin 1 $\\$ An anti-Baryon of electric charge +2 $\\$ [10 Marks][2022]
Which of the following decays are allowed and which are forbidden? If the decay is allowed, state which interaction is responsible. If it is forbidden, state which conservation law its occurrence would violate.
$n\longrightarrow p+e^-+v_e$
$\land^\circ\longrightarrow\pi^++\pi^-$
$\pi^-\longrightarrow e^-+\gamma$
$\pi^\circ\longrightarrow e^-+e^++v_e+v_e$
$\pi^+\longrightarrow e^-+e^++\mu^++v_\mu$ $\\$ [15 Marks][2022]