Azimuthal correlation between beauty particles produced in 350 GeV/c π - -Cu interactions

TLDR: This paper measured the azimuthal correlation between beauty particles, and compared their result with predictions based on perturbative QCD, using a sample of 108 triggered events, produced in 350 GeV /c π− interactions in a copper target.

About: This article is published in Physics Letters B.The article was published on 1998-08-06 and is currently open access. It has received 7 citations till now. The article focuses on the topics: Perturbative QCD & Measure (physics).

Figures

Figure 2: Distribution from simulated beauty events of the azimuthal angle, , between

Table 1: Comparison between the sample of beauty events obtained experimentally and a sample of simulated beauty events identi ed using the same selection criteria. Data for the simulation (13500 b b events generated) are normalized such that the number of selected beauty events is the same as is found experimentally. The statistical uctuations associated with each number are indicated.

Figure 3: Two views of a b b event in which both beauty decays (marked B) are visible. The primary interaction occurs at point P. A vertex (D) consistent with the decay of a charmed hadron from the more downstream beauty particle is also reconstructed. The beam is along the x axis (left view). In the transverse view (right), the azimuthal angle between the beauty particles is seen to be about 180 .

Figure 4: Reconstruction acceptance of beauty pairs as a function of .

Figure 1: Azimuthal correlation between beauty quarks (solid line) and between beauty hadrons (dotted line), as given by Pythia. Distributions are normalized to the number of beauty pairs (13) used in the WA92 analysis.

Figure 5:WA92 measurement of the distribution compared with: a) distributions given by NLO QCD for 0 = mb (solid line), 0 = 1 2 mb (dashed line), 0 = 2mb (dotted line); b) distributions given by NLO QCD for 0 = mb and hkT 2 i = 0GeV2=c2 (solid line), hkT 2 i = 0:5GeV2=c2 (dashed line), hkT 2 i = 1GeV2=c2 (dotted line) and hkT 2 i = 2GeV2=c2 (dashed-dotted line); c) E653 measurement [2] for beauty particles; d) WA92 measurement [11] for charmed particles. All distributions are normalized to the number of beauty pairs (13) used in the WA92 analysis.

Frequently asked questions

Q1. What are the contributions in "European organization for nuclear research" ?

The authors measure the azimuthal correlation between beauty particles, and compare their result with predictions based on perturba- 

Q2. What is the nal condition to be used in the measurement?

As a nal condition to be satis ed by a b b event to be used in their measurement, the authors require a transverse decay length of > 20 m for one of the beauty particles and of > 50 m for the associated beauty particle. 

Q3. how many b b events are emitted?

Among the simulated b b events with two identi ed beauty-decay vertices, from a simulation of 13500 b b events, the number in which the value measured after reconstruction di ers from the generated (true) value by less than the chosen bin width is 68=82 = 83% before imposing the requirement on transverse decay length and 66=72 = 92% afterwards. 

Q4. What is the strongest peaking at 180 in the case of the beauty particles?

The stronger peaking at 180 in the case of the beauty particles is consistent with a lower sensitivity to hadronization and NLO e ects. 

Q5. What is the significance of the distribution of beauty particles?

It is noted that the theoretical predictions [3] of the distribution for beauty particles are strongly in uenced only by the hkT 2 i value, whereas predictions for charmed particles are sensitive to several factors (choice of input parameters for perturbative calculations, corrections beyond NLO, hadronization, hkT 2 i value). 

Q6. What is the sensitivity of the hkT 2 i value?

Their result, which is consistent with the only previous measurement, for 9 b b events, is well described by NLO QCD if the interacting partons are assumed to have a mean transverse momentum squared of between 0:5GeV2=c2 and 1GeV2=c2.