Radiative angular distributions from<i>cc¯</i>states directly produced by<i>pp¯</i>annihilation

Olsson, M. G.; Suchyta, Casimir J.

doi:10.1103/physrevd.34.2043

Cited by 25 publications

(30 citation statements)

References 5 publications

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“…Again, we give the results for the J 4 0, J41 and the J 4 2 cases separately in terms of the helicity amplitudes A n and E s and the coefficients a d L 3 . In calculating eqs.…”

Section: -Partially Integrated Angular Distributionsmentioning

confidence: 99%

“…Their relative phases, therefore, are nontrivial and it is important to obtain them from experiment. In principle one should be able to extract their relative magnitudes as well as their relative phases by studying the angular distribution [2][3][4] of the decay products of charmonium states directly produced in pp collisions. In order to obtain the overall absolute magnitudes of the helicity amplitudes one has to also measure the branching ratios for the different decays as well as the total decay width of the charmonium states.…”

Section: -Introductionmentioning

confidence: 99%

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Angular distributions in the decays of the ψ’ charmonium state directly produced in polarized proton-antiproton collisions

Mok

Sebastian

1997

Nuov Cim A

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Summary. -In this paper we calculate the combined angular distribution of the two gamma photons and of the electron in the triple cascade process pp K c 8Kx J 1 g 1 K (cg 2 ) 1 g 1 K (e 1 e 2 ) 1 g 1 1 g 2 (J 4 0 , 1 , 2 ), when the proton p and the antiproton p are both arbitrarily polarized. Our final result is valid in the pp c.m. frame and it is expressed in terms of the Wigner D J functions whose arguments are the angles representing the various directions involved. The coefficients of the terms involving the Wigner D J functions are functions of the angular-momentum helicity amplitudes or equivalently of the multipole amplitudes in the radiative processes. They are also functions of the components of the polarization vectors of the proton and of the antiproton in their respective rest frames. We also derive six different partially integrated angular-distribution functions where the combined angulardistribution function of the three particles is integrated over the directions of one or two particles. Our results show that by measuring the angular distribution of single particles, namely g 1 , g 2 and e 2 , alone at a time, we can obtain the relative magnitudes and the relative phases of all the helicity amplitudes in the individual processes, pp K c 8 , c 8Kx J 1g 1 and x J K c 1 g 2 for the J 4 0 and the J 4 1 cases. For the J 4 2 case, we can get complete information on the helicity amplitudes in the processes pp K c 8 and c 8Kx 2 1g 1 . We can also obtain the relative magnitudes of the helicity amplitudes in the decay process x 2 K c 1 g 2 . In order to obtain the relative phases of these amplitudes uniquely, one has to measure the simultaneous angular distribution of the electron and of g 2 . PACS 11.80.Cr -Kinematical properties (helicity and invariant amplitudes, kinematic singularities, etc.). PACS 11.90 -Other topics in general fields and particle theory.

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“…Again, we give the results for the J 4 0, J41 and the J 4 2 cases separately in terms of the helicity amplitudes A n and E s and the coefficients a d L 3 . In calculating eqs.…”

Section: -Partially Integrated Angular Distributionsmentioning

confidence: 99%

Section: -Introductionmentioning

confidence: 99%

Angular distributions in the decays of the ψ’ charmonium state directly produced in polarized proton-antiproton collisions

Mok

Sebastian

1997

Nuov Cim A

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“…The helicity amplitudes A J jj can be expanded in multipole amplitudes (E1, M2, E3), see for example [43]. With the restriction to electric dipole transitions the helicity amplitudes become…”

Section: Appendix: C Angular Distributionsmentioning

confidence: 99%

“…The angular decay distribution of a pure polarization state jJ; Mi is given as an expansion into helicity amplitudes A J jj by [43] W J;M ð; 0 ; 0 Þ ¼ X þJ…”

Section: Appendix: C Angular Distributionsmentioning

confidence: 99%

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Production of the charmonium statesχc1andχc2in proton nucleus interactions at
Abt¹,
Adams²,
Agari³
et al. 2009
Phys. Rev. D
27
0
13
0
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A measurement of the ratio R c ¼ ð c ! J=c þ Þ=J=c in pC, pTi, and pW interactions at 920 GeV=c ( ffiffi ffi s p ¼ 41:6 GeV) in the Feynman-x range À0:35 < x J=c F < 0:15 is presented. Both þ À and e þ e À J=c decay channels are observed with an overall statistics of about 15 000 c events, which is by far the largest available sample in pA collisions. The result is R c ¼ 0:188 AE 0:013 st þ0:024 À0:022sys averaged over the different materials, when no J=c and c polarizations are considered. The c1 to c2 production ratio R 12 ¼ R c 1 =R c 2 is measured to be 1:02 AE 0:40, leading to a cross section ratio ð c1 Þ ð c2 Þ ¼ 0:57 AE 0:23. The dependence of R c on the Feynman-x of the J=c , x J=c F , and its transverse momentum, p J=c T , is studied, as well as its dependence on the atomic number, A, of the target. For the first time, an extensive study of possible biases on R c and R 12 due to the dependence of acceptance on the polarization states of J=c and c is performed. By varying the polarization parameter, obs , of all produced J=c 's by two sigma around the value measured by HERA-B, and considering the maximum variation due to the possible c1 and c2 polarizations, it is shown that R c could change by a factor between 1.02 and 1.21 and R 12 by a factor between 0.89 and 1.16.

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A simple and robust method to measure and polarizations

Faccioli

Lourenço

Seixas

et al. 2011

Nuclear Physics B - Proceedings Supplements

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Radiative angular distributions fromcc¯states directly produced bypp¯annihilation

Cited by 25 publications

References 5 publications

Angular distributions in the decays of the ψ’ charmonium state directly produced in polarized proton-antiproton collisions

Angular distributions in the decays of the ψ’ charmonium state directly produced in polarized proton-antiproton collisions

Production of the charmonium statesχc1andχc2in proton nucleus interactions at
Abt¹,
Adams²,
Agari³
et al. 2009
Phys. Rev. D
27
0
13
0
View full text Add to dashboard Cite

A simple and robust method to measure and polarizations

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Radiative angular distributions fromcc¯states directly produced bypp¯annihilation

Cited by 25 publications

References 5 publications

Angular distributions in the decays of the ψ’ charmonium state directly produced in polarized proton-antiproton collisions

Angular distributions in the decays of the ψ’ charmonium state directly produced in polarized proton-antiproton collisions

Production of the charmonium statesχc1andχc2in proton nucleus interactions atAbt1, Adams2, Agari3 et al. 2009Phys. Rev. D270130View full textAdd to dashboardCite

A simple and robust method to measure and polarizations

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About

Production of the charmonium statesχc1andχc2in proton nucleus interactions at
Abt¹,
Adams²,
Agari³
et al. 2009
Phys. Rev. D
27
0
13
0
View full text Add to dashboard Cite