Electroproduction of<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msup><mml:mrow><mml:mi>ρ</mml:mi></mml:mrow><mml:mrow><mml:mn>0</mml:mn></mml:mrow></mml:msup></mml:mrow></mml:math>mesons

Cohen, I.; Gebert, W.; Stein, P. C.; Preissner, H.; Janata, F.; Drews, G.; Erickson, R.; Söding, P.; Nordberg, E.; Sadoff, A. J.; Nagel, Hans-Hellmut; Ladage, A.; Siemann, R.H.; Joos, P.; Smith-Kintner, J.; Messing, F.

doi:10.1103/physrevd.25.634

Cited by 23 publications

(17 citation statements)

References 32 publications

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“…Other elements, ρ 10 and ρ 1−1 , can be studied by further measuring W (θ, φ). In fact, such measurements have already been carried out in lepton induced reactions and hadron-hadron collisions [4,5,6,7,8,9,10,11,12,13,16,17,18]. Unlike the polarization of hyperons, the spin-alignment of vector mesons, ρ V 00 , does not know the direction of the reaction plane since it only depends on cos 2 θ [see Eq.…”

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confidence: 99%

Spin alignment of vector mesons in non-central A+A collisions

2005

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We discuss the consequence of global polarization of the produced quarks in non-central heavy-ion collisions on the spin alignment of vector mesons. We show that the alignment is quite different for different hadronization scenarios. These results can be tested directly by measuring the vector mesons' alignment through angular distributions of the decay products with respect to the reaction plane. Such angular distributions will give rise to azimuthal anisotropy v2 of the decay products in the collision frame. Constraints provided by the data on the azimuthal anisotropy of hadron spectra at RHIC points to a quark recombination scenario of hadronization.PACS numbers: 13.88.+e, 12.38.Mh, 25.75.Nq Due to the presence of a large orbital angular momentum of the parton system produced at the early stage of non-central heavy-ion collisions, quarks and anti-quarks are shown recently [1] to be polarized in the direction opposite to the reaction plan which is determined by the vector of impactparameter and the beam momentum. Such global quark polarization should have many observable consequences such as left-right (with respect to the quarks' spin polarization) asymmetry in hadron spectra at large rapidity, global polarization of thermal photons, dileptons and final hadrons with spin. The left-right asymmetry of hadrons from the hadronization of such globally polarized quarks effectively gives rise to a "directed flow". However, it is difficult to disentangle it from the true directed flow due to interaction between produced matter and the spectator nucleons. Global hyperon polarization from the hadronization of polarized quarks are predicted [1] independently of the hadronization scenarios. Measurements of such global hyperon polarization are made possible by the self-analyzing power of the hyperon's parity-violating decay [2], which produces an angular distribution, dN/d cos θ = 1 + αP H cos θ, for its decay products with respect to the polarization direction. Here, α is a constant (e.g., α = 0.642 for Λ → pπ − ) and P H is the hyperon's polarization. In practice, one needs to know not only the orientation but also the sign (or direction) of the reaction plane which can only be determined by the directed flow in each event class. If one sums over events with opposite reaction planes, the effect of the hyperon's polarization on the angular distribution of its decay products will cancel. While such measurements are underway, other consequences can and should be studied.In this note, we discuss the spin alignment of vector mesons due to the global quark polarization in non-central A + A collisions. Similarly as in Ref.[1], we consider two colliding nuclei with the projectile of beam momentum p moving in the direction of the z axis. The impact parameter b is taken as alongx, which is the transverse distance of the projectile from the target nucleus. The norm of the reaction plane is given by n b ≡ p × b/| p × b| and is alongŷ. For a non-central collision, the dense matter produced in the overlapped region of the collisi...

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confidence: 99%

Spin alignment of vector mesons in non-central A+A collisions

2005

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“…I n fact, a better fit can be obtained with a power law relation (dashed curve in Fig. 4), with fl = 100 ps, y' = 2.5 x lo1' s-l, No = 10le could be consistent with band filling in a band tail of the form [8] and a u 1.1. This behaviour where e is the energy, measured downward from the virtual crystal exciton energy.…”

Section: Nonlinear R E S O N U R N Smentioning

confidence: 89%

“…The relation between the parameters go, E, , and B in (4) and the observed density dependence will depend on the actual dephasing mechanism in the band tail states. If for example the scattering is by thermal excitation into extended states above a, more or less well defined, mobility edge [8,9,121, one might expect for r 1, e0 = u akT N 0.4 meV. This would suggest a very shallow band tail which may be difficult to reconcile with the observed thermal activation energy for the dephasing rate.…”

Section: Nonlinear R E S O N U R N Smentioning

confidence: 98%

“…I n the pure crystals, the optical nonlinearities are dominated by exciton interactions a t low and medium intensities. In the mixed crystals, the unavoidable compositional disorder gives rise t o a fluctuating potential that tends t o localize the excitons [8,9], dramatically changing the linear as well as the nonlinear optical properties.…”

Section: Introductionmentioning

confidence: 99%

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Optical Nonlinearity and Phase Coherence in CdSe and CdSe_xS_1−x

Hvam¹,

Dörnfeld²,

Schwab³

1988

Physica Status Solidi (b)

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The magnitude of the optical nonlinearity and its phase coherence are investigated at low temperatures in single crystals of CdSe and CdSe,S1using picosecond time resolved degenerate fourwave mixing. In the pure compoupd semiconductors, the optical nonlinearity as well as the dephasing is governed by free exciton and biexeiton interactions. I n the mixed crystals, excitons localized by the alloy disorder play the dominant role, giving rise to larger nonlinearities and longer dephasing times than in the pure compounds.

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“…Measurements have been carried out in different reactions [13][14][15][16] in particular in e + e − annihilation at LEP recently 16 . The data 16 show that ρ 00 is significantly larger than 1/3 for vector mesons with large z and increases with increasing z (here z ≡ 2p V / √ s, where p V is the momentum of the vector meson, √ s is the total e + e − center of mass energy).…”

Section: Introductionmentioning

confidence: 99%

Spin alignment of the highpTvector mesons in polarizedppcollisions at high energies

Liang

2003

Phys. Rev. D

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Using the same method as that used in e + e − annihilation and lepton-nucleon deepinelastic scattering, we calculate the spin alignment of vector mesons with high transverse momenta in high energy pp collisions with one longitudinally polarized beam.We present the results obtained at RHIC energies. We also study the spin alignment of such vector mesons in the case of a transversely polarized proton beam and present its relation to the transversity distribution in the nucleon. Numerical results obtained using simple models for the transversity distributions are also given. These results show that there exist significant spin alignment in both cases, and they can be measured in experiments such as those at RHIC.

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Electroproduction ofρ0mesons

Cited by 23 publications

References 32 publications

Spin alignment of vector mesons in non-central A+A collisions

Spin alignment of vector mesons in non-central A+A collisions

Optical Nonlinearity and Phase Coherence in CdSe and CdSe_xS_1−x

Spin alignment of the highpTvector mesons in polarizedppcollisions at high energies

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Electroproduction ofρ0mesons

Cited by 23 publications

References 32 publications

Spin alignment of vector mesons in non-central A+A collisions

Spin alignment of vector mesons in non-central A+A collisions

Optical Nonlinearity and Phase Coherence in CdSe and CdSexS1−x

Spin alignment of the highpTvector mesons in polarizedppcollisions at high energies

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Product

Resources

About

Optical Nonlinearity and Phase Coherence in CdSe and CdSe_xS_1−x