Measurement of the forward-backward asymmetry of $\Lambda$ and $\bar{\Lambda}$ production in $p \bar{p}$ collisions

The D0 collaboration Abazov, Victor Mukhamedovich ; Abbott, Braden Keim ; Acharya, Bannanje Sripath ; et al.
Phys.Rev.D 93 (2016) 032002, 2016.
Inspire Record 1404885 DOI 10.17182/hepdata.76972

We study $\Lambda$ and $\bar{\Lambda}$ production asymmetries in $p \bar{p} \rightarrow \Lambda (\bar{\Lambda}) X$, $p \bar{p} \rightarrow J/\psi \Lambda (\bar{\Lambda}) X$, and $p \bar{p} \rightarrow \mu^\pm \Lambda (\bar{\Lambda}) X$ events recorded by the D0 detector at the Fermilab Tevatron collider at $\sqrt{s} = 1.96$ TeV. We find an excess of $\Lambda$'s ($\bar{\Lambda}$'s) produced in the proton (antiproton) direction. This forward-backward asymmetry is measured as a function of rapidity. We confirm that the $\bar{\Lambda}/\Lambda$ production ratio, measured by several experiments with various targets and a wide range of energies, is a universal function of "rapidity loss", i.e., the rapidity difference of the beam proton and the lambda.

2 data tables

Forward-backward asymmetry $A_{FB}$ of $\Lambda$ and $\bar{\Lambda}$ with $p_T > 2.0$ GeV in minimum bias events $p \bar{p} \rightarrow \Lambda (\bar{\Lambda}) X$, events $p \bar{p} \rightarrow J/\psi \Lambda (\bar{\Lambda}) X$, and events $p \bar{p} \rightarrow \mu^\pm \Lambda (\bar{\Lambda}) X$.

Forward-backward asymmetry $A_{FB}$ of $\Lambda$ and $\bar{\Lambda}$ in bins of $p_T$ in events $p \bar{p} \rightarrow \mu^\pm \Lambda (\bar{\Lambda}) X$.


Production of kshort, kstar(892)and phi(1020) in minimum bias events and kshort and lambda in jets in pbar p collisions at sqrt(s)=1.96 TeV

The CDF collaboration Aaltonen, T. ; Albrow, M. ; Alvarez Gonzalez, B. ; et al.
Phys.Rev.D 88 (2013) 092005, 2013.
Inspire Record 1247975 DOI 10.17182/hepdata.64398

We report measurements of the inclusive transverse momentum pT distribution of centrally produced kshort, kstar(892), and phi(1020) mesons up to pT = 10 GeV/c in minimum-bias events, and kshort and lambda particles up to pT = 20 GeV/c in jets with transverse energy between 25 GeV and 160 GeV in pbar p collisions. The data were taken with the CDF II detector at the Fermilab Tevatron at sqrt(s) = 1.96 TeV. We find that as pT increases, the pT slopes of the three mesons (kshort, kstar, and phi) are similar, and the ratio of lambda to kshort as a function of pT in minimum-bias events becomes similar to the fairly constant ratio in jets at pT ~ 5 GeV/c. This suggests that the particles with pT >~ 5 GeV/c in minimum-bias events are from soft jets, and that the pT slope of particles in jets is insensitive to light quark flavor (u, d, or s) and to the number of valence quarks. We also find that for pT <~ 4 GeV relatively more lambda baryons are produced in minimum-bias events than in jets.

5 data tables

The inclusive invariant differential cross section for K0S production.

The inclusive invariant differential cross section for PHI production.

The inclusive invariant differential cross section for K*(892)+- production.

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Production of Lambda, Cascade and Omega Hyperons in ppbar Collisions at1.96 TeV Center of Mass Energy

The CDF collaboration Aaltonen, T. ; Alvarez Gonzalez, B. ; Amerio, S. ; et al.
Phys.Rev.D 86 (2012) 012002, 2012.
Inspire Record 884451 DOI 10.17182/hepdata.63825

We report a set of measurements of inclusive invariant transverse momentum differential cross sections of lambda, cascade and omega hyperons reconstructed in the central region with pseudorapidity within 1 and transverse momentum up to 10 GeV/c Events are collected with a minimum-bias trigger in ppbar collisions at a center-of-mass energy of 1.96 TeV using the CDF II detector at the Tevatron Collider. As transverse momentum increases, the slopes of the differential cross sections are similar not only to each other but also to those of mesons, which could indicate a universality of the particle production in transverse momentum The invariant differential cross sections are also presented for different charged-particle multiplicity intervals.

5 data tables

The PT differential cross section for LAMBBA production in the |pseudorapidity| range < 1.

The PT differential cross section for XI- production in the |pseudorapidity| range < 1.

The PT differential cross section for OMEGA- production in the |pseudorapidity| range < 1.

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Test of {CP} Invariance in $\Lambda^0$ Decay

The R608 collaboration Chauvat, P. ; Erhan, S. ; Hayes, K. ; et al.
Phys.Lett.B 163 (1985) 273-276, 1985.
Inspire Record 216802 DOI 10.17182/hepdata.49640

In an experiment at the CERN intersecting storage rings with √ s = 31 GeV, we have measured αP , the product of asymmetry parameter and polarization, for Λ 0 's and Λ 0 's produced in p p and pp interactions, respectively. The ratio, (αP) Λ /(αP Λ = −1.04±0.29 , is consistent with the value −1, and constitutes the first test of CP invariance in Λ decay.

1 data table

The ratio CONST/CONST is obtained under assumption of POL(LAMBDA) = POL(LAMBDABAR).


Inclusive production of strange particles p anti-p collisions at s**(1/2) = 630-GeV with UA1

Bocquet, G. ; Norton, A. ; Wang, H.Q. ; et al.
Phys.Lett.B 366 (1996) 441-446, 1996.
Inspire Record 403648 DOI 10.17182/hepdata.48059

We have analysed a sample of 2.36 million minimum bias events produced in p p collisions at s =630 GeV in the UA1 experiment at the CERN Sp p S collider. We have studied the production of K S 0 , Λ and Λ particles with transverse momenta ( p t ) up to 7 GeV/c and K ± up to 2 GeV/c. The kaon data are compared with a recent QCD prediction and are found to be in good agreement. The < p t > for K S 0 , Λ and Λ is seen to increase as a function of the charged particle multiplicity and is compared with charged particle production.

8 data tables

No description provided.

K0S Distribution parametrised in the form E*D3SIG/DP**3 = A / (1+ pT/pT0)**N. Best fit values for A, pT0 and N are given here.

No description provided.

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A Study of particle ratios and strangeness suppression in p anti-p collisions at s**(1/2) = 630-GeV with UA1

Bocquet, G. ; Norton, A. ; Wang, H.Q. ; et al.
Phys.Lett.B 366 (1996) 447-450, 1996.
Inspire Record 403647 DOI 10.17182/hepdata.48043

From a sample of 2.36 million minimum bias events produced in p p collisions at s =630 GeV in the UA1 experiment and from other published data at the CERN S p p S collider we have estimated the relative production of π ± , π 0 , K ± , K S 0 , Λ, Λ , p and p . We obtain a meson over baryon ratio M B = 6.4 ± 1.1 . From the K S 0 π ± ratio we measure the strangeness suppression factor λ = 0.29 ± 0.02 ± 0.01 which, combining with other available data provides a new world average of 0.29 ± 0.015. Both the K S 0 π ± ratio and the strangeness suppression factor λ as a function of s are investigated, and an extrapolation to the LHC energy is performed.

2 data tables

Extrapolation to pt=0.

CONST is strangeness suppression factor, extracted from KS/PI+- ratio (see text).


Hyperon Production at 200-{GeV} and 900-{GeV} Center-of-mass Energy

The UA5 collaboration Ansorge, R.E. ; Asman, B. ; Burow, L. ; et al.
Nucl.Phys.B 328 (1989) 36-58, 1989.
Inspire Record 277298 DOI 10.17182/hepdata.33174

The production of Λ 's and Ξ − 's in proton-antiproton collisions at 200 and 900 GeV c.m. energy has been studied using decays observed in the UA5 streamer chambers. The results are compared to previously published 546 GeV data, to results from other experiments, and to four theoretical models. The Λ yield per inelastic event is estimated to be 0.42±0.11 at 200 GeV and 0.66±0.14 at 900 GeV. We find a mean number of Ξ − 's per inelastic collision of 0.03 −0.02 +0.04 at 200 GeV and 0.06 −0.03 +0.05 at 900 GeV. The average transverse momentum of Λ's in the rapidity region | y |⩽2 is found to be 0.80 −0.14 +0.20 GeV/ c at 200 GeV and 0.74±0.09 GeV/ c at 900 GeV. The average transverse momentum of Ξ − 's in the rapidity region | y |⩽3 is estimated to be 0.8 −0.2 +0.4 GeV/ c at 200 GeV and 0.7 −0.1 +0.2 GeV/ c at 900 GeV which is lower than the unexpectedly high value of 1.1±0.2 GeV/ c measured at 546 GeV. The ratio of Ξ − production to Λ production in the region | y |⩽2, p t >1 GeV/ c is 0.07 −0.04 +0.08 at 900 GeV. This value is consistent with the ratio found in e + e − collisions and lower energy pp collisions but lower than the value obtained at 546 GeV. The average particle composition of events at 200 and 900 GeV, estimated using UA5 data, is presented.

9 data tables

Corrected lambda transverse momentum distributions. Numerical values supplied by F. Lotse. Data at 546 GeV are taken from an earlier publication - Phys. Rep. 154 (87) 247.

Data at 546 GeV are taken from an earlier publication - Phys. Rep. 154 (87) 247.

Corrected lambda transverse momentum distributions. Numerical values supplied by F. Lotse. Data at 546 GeV are taken from an earlier publication - Phys. Rep. 154 (87) 247.

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Differences in Leading Baryon Production From $p \bar{p}$ and $p p$ Collisions With $\sqrt{s}=31$-{GeV} at the {CERN} {ISR}

Chauvat, P. ; Cousins, R.D. ; Erhan, S. ; et al.
Phys.Lett.B 127 (1983) 384-388, 1983.
Inspire Record 190333 DOI 10.17182/hepdata.30717

Significant differences are observed between forward-produced Δ ++ (1232) and Λ 0 's in pp interactions and their corresponding anti-particles in p p interactions, as expected from quark counting and single q q annihilation. A possible relationship between these results and the p p -pp total cross section difference is discussed.

2 data tables

No description provided.

No description provided.