Higher-order multipole amplitudes in charmonium radiative transitions

Journal Article · Tue Dec 01 00:00:00 EST 2009 · Physical Review. D, Particles Fields

DOI:https://doi.org/10.1103/PHYSREVD.80.112003· OSTI ID:21313441

Artuso, M; Blusk, S; Khalil, S; Mountain, R; Randrianarivony, K; Skwarnicki, T; Stone, S; Wang, J C; Zhang, L M ^[1]; Bonvicini, G; Cinabro, D; Lincoln, A; Smith, M J; Zhou, P; Zhu, J ^[2]; Naik, P; Rademacker, J ^[3]; Asner, D M; Edwards, K W; Reed, J ^[4]

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1. Syracuse University, Syracuse, New York 13244 (United States)
2. Wayne State University, Detroit, Michigan 48202 (United States)
3. University of Bristol, Bristol BS8 1TL (United Kingdom)
4. Carleton University, Ottawa, Ontario, K1S 5B6 (Canada)

Using 24x10{sup 6} {psi}{sup '}{identical_to}{psi}(2S) decays in CLEO-c, we have searched for higher multipole admixtures in electric-dipole-dominated radiative transitions in charmonia. We find good agreement between our data and theoretical predictions for magnetic quadrupole (M2) amplitudes in the transitions {psi}{sup '}{yields}{gamma}{chi}{sub c1,c2} and {chi}{sub c1,c2}{yields}{gamma}J/{psi}, in striking contrast to some previous measurements. Let b{sub 2}{sup J} and a{sub 2}{sup J} denote the normalized M2 amplitudes in the respective aforementioned decays, where the superscript J refers to the angular momentum of the {chi}{sub cJ}. By performing unbinned maximum likelihood fits to full five-parameter angular distributions, we found the following values of M2 admixtures for J{sub {chi}}=1: a{sub 2}{sup J={sup 1}}=(-6.26{+-}0.63{+-}0.24)x10{sup -2} and b{sub 2}{sup J={sup 1}}=(2.76{+-}0.73{+-}0.23)x10{sup -2}, which agree well with theoretical expectations for a vanishing anomalous magnetic moment of the charm quark. For J{sub {chi}}=2, if we fix the electric octupole (E3) amplitudes to zero as theory predicts for transitions between charmonium S states and P states, we find a{sub 2}{sup J={sup 2}}=(-9.3{+-}1.6{+-}0.3)x10{sup -2} and b{sub 2}{sup J={sup 2}}=(1.0{+-}1.3{+-}0.3)x10{sup -2}. If we allow for E3 amplitudes we find, with a four-parameter fit, a{sub 2}{sup J={sup 2}}=(-7.9{+-}1.9{+-}0.3)x10{sup -2}, b{sub 2}{sup J={sup 2}}=(0.2{+-}1.4{+-}0.4)x10{sup -2}, a{sub 3}{sup J={sup 2}}=(1.7{+-}1.4{+-}0.3)x10{sup -2}, and b{sub 3}{sup J={sup 2}}=(-0.8{+-}1.2{+-}0.2)x10{sup -2}. We determine the ratios a{sub 2}{sup J={sup 1}}/a{sub 2}{sup J={sup 2}}=0.67{sub -0.13}{sup +0.19} and a{sub 2}{sup J={sup 1}}/b{sub 2}{sup J={sup 1}}=-2.27{sub -0.99}{sup +0.57}, where the theoretical predictions are independent of the charmed quark magnetic moment and are a{sub 2}{sup J={sup 1}}/a{sub 2}{sup J={sup 2}}=0.676{+-}0.071 and a{sub 2}{sup J={sup 1}}/b{sub 2}{sup J={sup 1}}=-2.27{+-}0.16.

• OSTI ID: 21313441
• Journal Information: Physical Review. D, Particles Fields, Vol. 80, Issue 11; Other Information: DOI: 10.1103/PhysRevD.80.112003; (c) 2009 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA); ISSN 0556-2821
• Country of Publication: United States
• Language: English

Related Subjects

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
AMPLITUDES
ANGULAR DISTRIBUTION
ANGULAR MOMENTUM
C QUARKS
CESR STORAGE RING
CHARMONIUM
E3-TRANSITIONS
ELECTRIC DIPOLES
GAMMA RADIATION
M2-TRANSITIONS
MAGNETIC MOMENTS
MAXIMUM-LIKELIHOOD FIT
MULTIPARTICLE SPECTROMETERS
OCTUPOLES
P STATES
PARTICLE DECAY
PARTICLE IDENTIFICATION
S STATES