# Forward-backward multiplicity correlations in pp collisions at √s = 0.9, 2.76 and 7 TeV

The ALICE collaboration

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14 Citations (Scopus)

### Abstract

Abstract: The strength of forward-backward (FB) multiplicity correlations is measured by the ALICE detector in proton-proton (pp) collisions at s$$\sqrt{s}$$ = 0.9, 2.76 and 7 TeV. The measurement is performed in the central pseudorapidity region (|η| <0.8) for the transverse momentum pT> 0.3 GeV/c. Two separate pseudorapidity windows of width (δη) ranging from 0.2 to 0.8 are chosen symmetrically around η = 0. The multiplicity correlation strength (bcorr) is studied as a function of the pseudorapidity gap (ηgap) between the two windows as well as the width of these windows. The correlation strength is found to decrease with increasing ηgap and shows a non-linear increase with δη. A sizable increase of the correlation strength with the collision energy, which cannot be explained exclusively by the increase of the mean multiplicity inside the windows, is observed. The correlation coefficient is also measured for multiplicities in different configurations of two azimuthal sectors selected within the symmetric FB η-windows. Two different contributions, the short-range (SR) and the long-range (LR), are observed. The energy dependence of bcorr is found to be weak for the SR component while it is strong for the LR component. Moreover, the correlation coefficient is studied for particles belonging to various transverse momentum intervals chosen to have the same mean multiplicity. Both SR and LR contributions to bcorr are found to increase with pT in this case. Results are compared to PYTHIA and PHOJET event generators and to a string-based phenomenological model. The observed dependencies of bcorr add new constraints on phenomenological models.[Figure not available: see fulltext.]

Original language English 97 Journal of High Energy Physics 2015 5 https://doi.org/10.1007/JHEP05(2015)097 Published - May 28 2015

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collisions
protons
correlation coefficients
transverse momentum
sectors
strings
generators
intervals
energy
detectors
configurations

### All Science Journal Classification (ASJC) codes

• Nuclear and High Energy Physics

### Cite this

Forward-backward multiplicity correlations in pp collisions at √s = 0.9, 2.76 and 7 TeV. / The ALICE collaboration.

In: Journal of High Energy Physics, Vol. 2015, No. 5, 97, 28.05.2015.

Research output: Contribution to journalArticle

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title = "Forward-backward multiplicity correlations in pp collisions at √s = 0.9, 2.76 and 7 TeV",
abstract = "Abstract: The strength of forward-backward (FB) multiplicity correlations is measured by the ALICE detector in proton-proton (pp) collisions at s$$\sqrt{s}$$ = 0.9, 2.76 and 7 TeV. The measurement is performed in the central pseudorapidity region (|η| <0.8) for the transverse momentum pT> 0.3 GeV/c. Two separate pseudorapidity windows of width (δη) ranging from 0.2 to 0.8 are chosen symmetrically around η = 0. The multiplicity correlation strength (bcorr) is studied as a function of the pseudorapidity gap (ηgap) between the two windows as well as the width of these windows. The correlation strength is found to decrease with increasing ηgap and shows a non-linear increase with δη. A sizable increase of the correlation strength with the collision energy, which cannot be explained exclusively by the increase of the mean multiplicity inside the windows, is observed. The correlation coefficient is also measured for multiplicities in different configurations of two azimuthal sectors selected within the symmetric FB η-windows. Two different contributions, the short-range (SR) and the long-range (LR), are observed. The energy dependence of bcorr is found to be weak for the SR component while it is strong for the LR component. Moreover, the correlation coefficient is studied for particles belonging to various transverse momentum intervals chosen to have the same mean multiplicity. Both SR and LR contributions to bcorr are found to increase with pT in this case. Results are compared to PYTHIA and PHOJET event generators and to a string-based phenomenological model. The observed dependencies of bcorr add new constraints on phenomenological models.[Figure not available: see fulltext.]",
author = "{The ALICE collaboration} and J. Adam and D. Adamov{\'a} and Aggarwal, {M. M.} and {Aglieri Rinella}, G. and M. Agnello and N. Agrawal and Z. Ahammed and I. Ahmed and Ahn, {S. U.} and I. Aimo and S. Aiola and M. Ajaz and A. Akindinov and Alam, {S. N.} and D. Aleksandrov and B. Alessandro and D. Alexandre and {Alfaro Molina}, R. and A. Alici and A. Alkin and J. Alme and T. Alt and S. Altinpinar and I. Altsybeev and {Alves Garcia Prado}, C. and C. Andrei and A. Andronic and V. Anguelov and J. Anielski and T. Antičić and F. Antinori and P. Antonioli and L. Aphecetche and H. Appelsh{\"a}user and S. Arcelli and N. Armesto and R. Arnaldi and T. Aronsson and Arsene, {I. C.} and M. Arslandok and A. Augustinus and R. Averbeck and Azmi, {M. D.} and M. Bach and A. Badal{\`a} and Baek, {Y. W.} and S. Bagnasco and R. Bailhache and Cherney, {Michael G.} and Seger, {Janet E.}",
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T1 - Forward-backward multiplicity correlations in pp collisions at √s = 0.9, 2.76 and 7 TeV

AU - The ALICE collaboration

AU - Aggarwal, M. M.

AU - Aglieri Rinella, G.

AU - Agnello, M.

AU - Agrawal, N.

AU - Ahammed, Z.

AU - Ahmed, I.

AU - Ahn, S. U.

AU - Aimo, I.

AU - Aiola, S.

AU - Ajaz, M.

AU - Akindinov, A.

AU - Alam, S. N.

AU - Aleksandrov, D.

AU - Alessandro, B.

AU - Alexandre, D.

AU - Alfaro Molina, R.

AU - Alici, A.

AU - Alkin, A.

AU - Alme, J.

AU - Alt, T.

AU - Altinpinar, S.

AU - Altsybeev, I.

AU - Alves Garcia Prado, C.

AU - Andrei, C.

AU - Andronic, A.

AU - Anguelov, V.

AU - Anielski, J.

AU - Antičić, T.

AU - Antinori, F.

AU - Antonioli, P.

AU - Aphecetche, L.

AU - Appelshäuser, H.

AU - Arcelli, S.

AU - Armesto, N.

AU - Arnaldi, R.

AU - Aronsson, T.

AU - Arsene, I. C.

AU - Arslandok, M.

AU - Augustinus, A.

AU - Averbeck, R.

AU - Azmi, M. D.

AU - Bach, M.

AU - Baek, Y. W.

AU - Bagnasco, S.

AU - Bailhache, R.

AU - Cherney, Michael G.

AU - Seger, Janet E.

PY - 2015/5/28

Y1 - 2015/5/28

N2 - Abstract: The strength of forward-backward (FB) multiplicity correlations is measured by the ALICE detector in proton-proton (pp) collisions at s$$\sqrt{s}$$ = 0.9, 2.76 and 7 TeV. The measurement is performed in the central pseudorapidity region (|η| <0.8) for the transverse momentum pT> 0.3 GeV/c. Two separate pseudorapidity windows of width (δη) ranging from 0.2 to 0.8 are chosen symmetrically around η = 0. The multiplicity correlation strength (bcorr) is studied as a function of the pseudorapidity gap (ηgap) between the two windows as well as the width of these windows. The correlation strength is found to decrease with increasing ηgap and shows a non-linear increase with δη. A sizable increase of the correlation strength with the collision energy, which cannot be explained exclusively by the increase of the mean multiplicity inside the windows, is observed. The correlation coefficient is also measured for multiplicities in different configurations of two azimuthal sectors selected within the symmetric FB η-windows. Two different contributions, the short-range (SR) and the long-range (LR), are observed. The energy dependence of bcorr is found to be weak for the SR component while it is strong for the LR component. Moreover, the correlation coefficient is studied for particles belonging to various transverse momentum intervals chosen to have the same mean multiplicity. Both SR and LR contributions to bcorr are found to increase with pT in this case. Results are compared to PYTHIA and PHOJET event generators and to a string-based phenomenological model. The observed dependencies of bcorr add new constraints on phenomenological models.[Figure not available: see fulltext.]

AB - Abstract: The strength of forward-backward (FB) multiplicity correlations is measured by the ALICE detector in proton-proton (pp) collisions at s$$\sqrt{s}$$ = 0.9, 2.76 and 7 TeV. The measurement is performed in the central pseudorapidity region (|η| <0.8) for the transverse momentum pT> 0.3 GeV/c. Two separate pseudorapidity windows of width (δη) ranging from 0.2 to 0.8 are chosen symmetrically around η = 0. The multiplicity correlation strength (bcorr) is studied as a function of the pseudorapidity gap (ηgap) between the two windows as well as the width of these windows. The correlation strength is found to decrease with increasing ηgap and shows a non-linear increase with δη. A sizable increase of the correlation strength with the collision energy, which cannot be explained exclusively by the increase of the mean multiplicity inside the windows, is observed. The correlation coefficient is also measured for multiplicities in different configurations of two azimuthal sectors selected within the symmetric FB η-windows. Two different contributions, the short-range (SR) and the long-range (LR), are observed. The energy dependence of bcorr is found to be weak for the SR component while it is strong for the LR component. Moreover, the correlation coefficient is studied for particles belonging to various transverse momentum intervals chosen to have the same mean multiplicity. Both SR and LR contributions to bcorr are found to increase with pT in this case. Results are compared to PYTHIA and PHOJET event generators and to a string-based phenomenological model. The observed dependencies of bcorr add new constraints on phenomenological models.[Figure not available: see fulltext.]

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U2 - 10.1007/JHEP05(2015)097

DO - 10.1007/JHEP05(2015)097

M3 - Article

AN - SCOPUS:84930225537

VL - 2015

JO - Journal of High Energy Physics

JF - Journal of High Energy Physics

SN - 1126-6708

IS - 5

M1 - 97

ER -