On the general theory of collisions for particles with spin

Jacob, M.; Wick, G. C.

doi:10.1016/0003-4916(59)90051-x

Cited by 2,197 publications

(1,002 citation statements)

References 12 publications

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“…For details on the helicity amplitude formalism we refer the reader to [28]. Note that in the total helicity zero channel the reduced rotation matrix reduces to a Legendre polynomial, d (l) 00 (cos θ) = P l (cos θ), in agreement with equ.…”

Section: High Density Effective Theory (Hdet)supporting

confidence: 66%

Hard loops, soft loops, and high density effective field theory

Schäfer

2003

Nuclear Physics A

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We study several issues related to the use of effective field theories in QCD at large baryon density. We show that the power counting is complicated by the appearance of two scales inside loop integrals. Hard dense loops involve the large scale µ 2 and lead to phenomena such as screening and damping at the scale gµ. Soft loops only involve small scales and lead to superfluidity and non-Fermi liquid behavior at exponentially small scales. Four-fermion operators in the effective theory are suppressed by powers of 1/µ, but they get enhanced by hard loops. As a consequence their contribution to the pairing gap is only suppressed by powers of the coupling constant, and not powers of 1/µ. We determine the coefficients of four-fermion operators in the effective theory by matching quark-quark scattering amplitudes. Finally, we introduce a perturbative scheme for computing corrections to the gap parameter in the superfluid phase.

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Section: High Density Effective Theory (Hdet)supporting

confidence: 66%

Hard loops, soft loops, and high density effective field theory

Schäfer

2003

Nuclear Physics A

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“…The first arises from the two diagrams in the first row of Fig.1 and containsŝ-pole contributions generated by exchanging the CP-even neutral Higgs particles h 0 and H 0 . For theŝ-channel h 0 -case, this is given by 19) while for the H 0 -case we get 20) where the needed h 0 and H 0 couplings are given in (A.4, A.5). For such contributions we obviously also have…”

Section: Discussionmentioning

confidence: 99%

“…The diagrams in 3 For the gauge boson polarization vectors, here and in [13,14], we use the same conventions as in [18]. The only difference is that we use the JW convention [19], which introduces an additional minus to the polarization vector of a longitudinal "Number 2" Z and affects γγ → ZZ, γZ. 4 We use the same conventions as in [13,14].…”

Section: Introductionmentioning

confidence: 99%

The $\gamma \gamma \to A^0 A^0 $ process at a $\gamma \gamma $ collider

Gounaris

Porfyriadis

2000

Eur. Phys. J. C

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The helicity amplitudes for the process γγ → A 0 A 0 are studied to 1-loop order in the minimal SUSY (MSSM) model, where A 0 is the CP-odd Higgs particle. Simple exact analytic formulae are obtained, in terms of the C 0 and D 0 Passarino-Veltman functions; in spite of the fact that the loop-diagrams often involve different particles running along their sides. For a usual mSUGRA set of parameters, σ(γγ → A 0 A 0 ) ∼ (0.1−0.2)fb is expected. If SUSY is realized in Nature, these expressions should be useful for understanding the Higgs sector.

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“…[149]). But, in this particular case, where one of the two particles states has no polarization, the Wigner D-function reduces to eq.…”

Section: Partial Wave Decompositionmentioning

confidence: 99%