Particle Physics Past Papers

[OBJECTIVE]

Subject: Particle Physics-IV

Time Allowed: 15 Min

Total Marks: 10

NOTE: ATTEMPT THIS PAPER ON THIS QUESTION SHEET ONLY. Division of marks is given in front of each question. This Paper will be collected back after expiry of time limit mentioned above.

 

Part-I Encircle the correct option, each question carries equal marks. (10)

1. TrI =

(a) 0

(b) 4

(c) 1

(d) None of the above

2. In term of anti-symmetric field strength tensor, Maxwell’s equations take the compact form

5. e^–e⁺ → YY is the process.

(a) Pair creation

(b) Pair annihilation

(c) Scattering

(d) None of the above

6. The fine structure constant a is

(a)  4πe²

(b) 4π/e²

(c) e²/4π

(d} e²/4π²

7. In a non-relativistic limit ____________ of

(a) p→0

(b) lpl→0

(c) m→o

(d) Both (b) & (c)

8. Which of the following is Lorentz gauge condition

(a) 0,A, =0

(b) Q¥A* =0

(c) d*A, =0

(d) None of the above

9. The lowest order invariant amplitude of electron scattering by electromaguctic ficld has vetex factor(s).

(a) zero

(b) one

(c) two

(d) three

10. “t” is a Mandelstam variable which is defined as .

(a) (P_A + P_B)²

(b) (P_A – P_C)²

(c) (P_A – P_D)²

(d) (P_A – P_B)²

 

[SUBJECTIVE]

Subject: Particle Physics-IV

Time Allowed: 2 Hour 45 Min

Total Marks: 50

NOTE: ATTEMPT THIS (SUBJECTIVE) ON THE SEPARATE ANSWER SHEET PROVIDED

 

Part-II Give short answers, each question carries equal marks. (20)

Q#1: For a scattering process AB -> CD, show that s + i + u = m²_A + m²_B + m²_C + m²_D.

Q#2: Write an expression for decay rate of the process A → 1+2+3+4.

Q#3: Define lab frame of reference.

Q#4: Prove that Tr(Y5) = 0.

Q#5: Write u(k)yu(k) in terms of components of a matrix.

Q#6: Differentiate b/w real and virtual particles.

Q#7: Draw lowest order Feynman diagrams for Moller scattering. Also write the invariant amplitude follows from Feynman rules.

Q#8: Using equation of motion, write down the propagator for the relativistic ally moving spin-1/2 particle.

 

Part-III Give detailed answers, each question carries equal marks. (30)

 

---

[OBJECTIVE]

Subject: Particle Physics-III

Time Allowed: 15 Min

Total Marks: 10

NOTE: ATTEMPT THIS PAPER ON THIS QUESTION SHEET ONLY. Division of marks is given in front of each question. This Paper will be collected back after expiry of time limit mentioned above.

 

Part-I Encircle the correct option, each question carries equal marks. (10)

1. The combination ud belongs to an

(a) isospin doublet

(b) isospin triplet

(c) isospin singlet

(d) none of them

2. The rank of SU(3) group is

(a) 3

(b) 1

(c) 8

(d) 2

3. In scattering problem, if n₁ = 1, then

(a) inelastic scattering occurs

(b) symmetric potential is present

(c) elastic scattering occurs

(d) none of them

4. The unified Electromagnetic and Weak force can be explained by

(a) SU(3)

(b) SU(2) x U(1)

(c) U(1)

(d) SU(3) x U(1)

5. The plane wave solution in asymptotic region is a superposition of

(a) two spherical waves

(b) four spherical waves

(c) infinite partial waves

(d) none of them

6. The general formula to find number of generators of SU(n) is

(a) n²-n

(b) n²

(c) n²-1

(d) n²+1

7. When 6; is positive, then potential is

(a) attractive

(b) symmetric

(c) repulsive

(d) non central

8. The full width half maximum of resonance curve is related to

{a) life time of the state

(b) energy

(c) momentum

(d) all of these

9. In a weight diagram multiplicity decreases until __________ layer is reached

(a) single point

(b) triangular

-(c) hexagonal

(d) rectangular

10. The action of I₊ produces change of

(a) ΔY =0, ΔI₃ =1

(b) ΔY =0, ΔI₃ = -1

(c) ΔY =0, ΔI₃ = +1/2

(d) ΔY =0, ΔI₃ = 1/2

 

[SUBJECTIVE]

Subject: Particle Physics-III

Time Allowed: 2 Hour 45 Min

Total Marks: 50

NOTE: ATTEMPT THIS (SUBJECTIVE) ON THE SEPARATE ANSWER SHEET PROVIDED

 

Part-II Give short answers, each question carries equal marks. (20)

Q#1: Define H-type and E-type generators.

Q#2: Verify standard form of Lie algebra of SU2 group by showing [H1, E₊] = +1E₊

Q#3: Show that differential cross section has dimension of area.

Q#4: What is hadron spectroscopy?

Q#5: State optical theorem.

Q#6: What is Grand Unification Theory?

Q#7: Using [λi,λj] = 2if_ijkλ_k, find value of f₃₄₅.

Q#8: Define elastic and inelastic scattering.

Q#9: What is phase shift and how is it related to potential?

Q#10: What is Standard model of Particle Physics?

 

Part-III Give detailed answers, each question carries equal marks. (30)

Q#1: Derive the following Breit Wigner formula for elastic scattering of spineless particles. Also explain in detail its importance/use in Particle Physics.