A measurement of the production of prompt <math><msubsup><mrow><mi>Λ</mi></mrow><mrow><mi>c</mi></mrow><mrow><mo>+</mo></mrow></msubsup></math> baryons in Pb–Pb collisions at <math><msqrt><mrow><msub><mrow><mi>s</mi></mrow><mrow><mi>NN</mi></mrow></msub></mrow></msqrt><mo>=</mo><mn>5.02</mn></math> TeV with the ALICE detector at the LHC is reported. The <math><msubsup><mrow><mi>Λ</mi></mrow><mrow><mi>c</mi></mrow><mrow><mo>+</mo></mrow></msubsup></math> and <math><msup><mrow><msub><mrow><mover><mrow><mi>Λ</mi></mrow><mo>‾</mo></mover></mrow><mrow><mi>c</mi></mrow></msub></mrow><mrow><mo>−</mo></mrow></msup></math> were reconstructed at midrapidity (<math><mo>|</mo><mi>y</mi><mo>|</mo><mo>&lt;</mo><mn>0.5</mn></math>) via the hadronic decay channel <math><msubsup><mrow><mi>Λ</mi></mrow><mrow><mi>c</mi></mrow><mrow><mo>+</mo></mrow></msubsup><mo>→</mo><mi>p</mi><msubsup><mrow><mi>K</mi></mrow><mrow><mi>S</mi></mrow><mrow><mn>0</mn></mrow></msubsup></math> (and charge conjugate) in the transverse momentum and centrality intervals <math><mn>6</mn><mo>&lt;</mo><msub><mrow><mi>p</mi></mrow><mrow><mi>T</mi></mrow></msub><mo>&lt;</mo><mn>12</mn></math> GeV/c and 0–80%. The <math><msubsup><mrow><mi>Λ</mi></mrow><mrow><mi>c</mi></mrow><mrow><mo>+</mo></mrow></msubsup><mo>/</mo><msup><mrow><mi>D</mi></mrow><mrow><mn>0</mn></mrow></msup></math> ratio, which is sensitive to the charm quark hadronisation mechanisms in the medium, is measured and found to be larger than the ratio measured in minimum-bias pp collisions at <math><msqrt><mrow><mi>s</mi></mrow></msqrt><mo>=</mo><mn>7</mn></math> TeV and in p–Pb collisions at <math><msqrt><mrow><msub><mrow><mi>s</mi></mrow><mrow><mi>NN</mi></mrow></msub></mrow></msqrt><mo>=</mo><mn>5.02</mn></math> TeV. In particular, the values in p–Pb and Pb–Pb collisions differ by about two standard deviations of the combined statistical and systematic uncertainties in the common <math><msub><mrow><mi>p</mi></mrow><mrow><mi>T</mi></mrow></msub></math> interval covered by the measurements in the two collision systems. The <math><msup><mrow><msub><mrow><mi>Λ</mi></mrow><mrow><mi>c</mi></mrow></msub></mrow><mrow><mo>+</mo></mrow></msup><mo>/</mo><msup><mrow><mi>D</mi></mrow><mrow><mn>0</mn></mrow></msup></math> ratio is also compared with model calculations including different implementations of charm quark hadronisation. The measured ratio is reproduced by models implementing a pure coalescence scenario, while adding a fragmentation contribution leads to an underestimation. The <math><msubsup><mrow><mi>Λ</mi></mrow><mrow><mi>c</mi></mrow><mrow><mo>+</mo></mrow></msubsup></math> nuclear modification factor, <math><msub><mrow><mi>R</mi></mrow><mrow><mi>AA</mi></mrow></msub></math>, is also presented. The measured values of the <math><msub><mrow><mi>R</mi></mrow><mrow><mi>AA</mi></mrow></msub></math> of <math><msubsup><mrow><mi>Λ</mi></mrow><mrow><mi>c</mi></mrow><mrow><mo>+</mo></mrow></msubsup></math>, <math><msubsup><mrow><mi>D</mi></mrow><mrow><mi>s</mi></mrow><mrow><mo>+</mo></mrow></msubsup></math> and non-strange D mesons are compatible within the combined statistical and systematic uncertainties. They show, however, a hint of a hierarchy <math><mo>(</mo><msubsup><mrow><mi>R</mi></mrow><mrow><mi>AA</mi></mrow><mrow><msup><mrow><mi>D</mi></mrow><mrow><mn>0</mn></mrow></msup></mrow></msubsup><mo>&lt;</mo><msubsup><mrow><mi>R</mi></mrow><mrow><mi>AA</mi></mrow><mrow><msubsup><mrow><mi>D</mi></mrow><mrow><mi>s</mi></mrow><mrow><mo>+</mo></mrow></msubsup></mrow></msubsup><mo>&lt;</mo><msubsup><mrow><mi>R</mi></mrow><mrow><mi>AA</mi></mrow><mrow><msubsup><mrow><mi>Λ</mi></mrow><mrow><mi>c</mi></mrow><mrow><mo>+</mo></mrow></msubsup></mrow></msubsup><mo>)</mo></math>, conceivable with a contribution from coalescence mechanisms to charm hadron formation in the medium.

India

S. Acharya

United States

F.T. Acosta

Czechia

D. Adamová

S.P. Adhya

Germany

A. Adler

Sweden

J. Adolfsson

M.M. Aggarwal

CERN

G. Aglieri Rinella

Italy

M. Agnello

N. Agrawal

Z. Ahammed

S. Ahmad

South Korea

S.U. Ahn

S. Aiola

Russia

A. Akindinov

M. Al-Turany

S.N. Alam

Brazil

D.S.D. Albuquerque

D. Aleksandrov

B. Alessandro

China

H.M. Alfanda

Mexico

R. Alfaro Molina

Pakistan

Y. Ali

A. Alici

Ukraine

A. Alkin

Norway

J. Alme

T. Alt

L. Altenkamper

I. Altsybeev

M.N. Anaam

Romania

C. Andrei

D. Andreou

United Kingdom

H.A. Andrews

A. Andronic

M. Angeletti

V. Anguelov

C. Anson

Croatia

T. Antičić

F. Antinori

P. Antonioli

R. Anwar

N. Apadula

France

L. Aphecetche

H. Appelshäuser

S. Arcelli

R. Arnaldi

M. Arratia

I.C. Arsene

M. Arslandok

A. Augustinus

R. Averbeck

M.D. Azmi

A. Badalà

Y.W. Baek

S. Bagnasco

R. Bailhache

R. Bala

A. Baldisseri

M. Ball

R.C. Baral

R. Barbera

L. Barioglio

Hungary

G.G. Barnaföldi

L.S. Barnby

V. Barret

P. Bartalini

K. Barth

E. Bartsch

N. Bastid

S. Basu

G. Batigne

JINR

B. Batyunya

P.C. Batzing

Peru

J.L. Bazo Alba

Denmark

I.G. Bearden

H. Beck

Netherlands

C. Bedda

N.K. Behera

I. Belikov

F. Bellini

H. Bello Martinez

R. Bellwied

L.G.E. Beltran

V. Belyaev

G. Bencedi

S. Beole

A. Bercuci

Y. Berdnikov

D. Berenyi

R.A. Bertens

D. Berzano

L. Betev

A. Bhasin

I.R. Bhat

H. Bhatt

B. Bhattacharjee

Poland

J. Bhom

A. Bianchi

L. Bianchi

N. Bianchi

production in Pb–Pb collisions at TeV

Charged-particle spectra at midrapidity are measured in Pb–Pb collisions at the centre-of-mass energy per nucleon–nucleon pair <math><msqrt><mrow><msub><mrow><mi>s</mi></mrow><mrow><mi>NN</mi></mrow></msub></mrow></msqrt><mo>=</mo><mn>5.02</mn></math> TeV and presented in centrality classes ranging from most central (0–5%) to most peripheral (95–100%) collisions. Possible medium effects are quantified using the nuclear modification factor (<math><msub><mrow><mi>R</mi></mrow><mrow><mi>AA</mi></mrow></msub></math>) by comparing the measured spectra with those from proton–proton collisions, scaled by the number of independent nucleon–nucleon collisions obtained from a Glauber model. At large transverse momenta (<math><mn>8</mn><mo>&lt;</mo><msub><mrow><mi>p</mi></mrow><mrow><mi>T</mi></mrow></msub><mo>&lt;</mo><mn>20</mn><mspace width="0.25em"></mspace><mtext>GeV</mtext><mo>/</mo><mi>c</mi></math>), the average <math><msub><mrow><mi>R</mi></mrow><mrow><mi>AA</mi></mrow></msub></math> is found to increase from about 0.15 in 0–5% central to a maximum value of about 0.8 in 75–85% peripheral collisions, beyond which it falls off strongly to below 0.2 for the most peripheral collisions. Furthermore, <math><msub><mrow><mi>R</mi></mrow><mrow><mi>AA</mi></mrow></msub></math> initially exhibits a positive slope as a function of <math><msub><mrow><mi>p</mi></mrow><mrow><mi>T</mi></mrow></msub></math> in the 8–20 <math><mtext>GeV</mtext><mo>/</mo><mi>c</mi></math> interval, while for collisions beyond the 80% class the slope is negative. To reduce uncertainties related to event selection and normalization, we also provide the ratio of <math><msub><mrow><mi>R</mi></mrow><mrow><mi>AA</mi></mrow></msub></math> in adjacent centrality intervals. Our results in peripheral collisions are consistent with a PYTHIA-based model without nuclear modification, demonstrating that biases caused by the event selection and collision geometry can lead to the apparent suppression in peripheral collisions. This explains the unintuitive observation that <math><msub><mrow><mi>R</mi></mrow><mrow><mi>AA</mi></mrow></msub></math> is below unity in peripheral Pb–Pb, but equal to unity in minimum-bias p–Pb collisions despite similar charged-particle multiplicities.

O.W. Arnold

A.M. Barbano

F. Barile

P.P. Bhaduri

J. Bielčík

Analysis of the apparent nuclear modification in peripheral Pb–Pb collisions at 5.02 TeV

In this letter, the production of deuterons and anti-deuterons in pp collisions at <math><msqrt><mrow><mi>s</mi></mrow></msqrt><mo>=</mo><mn>7</mn></math> TeV is studied as a function of the charged-particle multiplicity density at mid-rapidity with the ALICE detector at the LHC. Production yields are measured at mid-rapidity in five multiplicity classes and as a function of the deuteron transverse momentum (<math><msub><mrow><mi>p</mi></mrow><mrow><mi>T</mi></mrow></msub></math>). The measurements are discussed in the context of hadron–coalescence models. The coalescence parameter <math><msub><mrow><mi>B</mi></mrow><mrow><mn>2</mn></mrow></msub></math>, extracted from the measured spectra of (anti-)deuterons and primary (anti-)protons, exhibits no significant <math><msub><mrow><mi>p</mi></mrow><mrow><mi>T</mi></mrow></msub></math>-dependence for <math><msub><mrow><mi>p</mi></mrow><mrow><mi>T</mi></mrow></msub><mo>&lt;</mo><mn>3</mn></math> <math><mtext>GeV</mtext><mspace width="-0.05em"></mspace><mo>/</mo><mspace width="-0.02em"></mspace><mi>c</mi></math>, in agreement with the expectations of a simple coalescence picture. At fixed transverse momentum per nucleon, the <math><msub><mrow><mi>B</mi></mrow><mrow><mn>2</mn></mrow></msub></math> parameter is found to decrease smoothly from low multiplicity pp to Pb–Pb collisions, in qualitative agreement with more elaborate coalescence models. The measured mean transverse momentum of (anti-)deuterons in pp is not reproduced by the Blast-Wave model calculations that simultaneously describe pion, kaon and proton spectra, in contrast to central Pb–Pb collisions. The ratio between the <math><msub><mrow><mi>p</mi></mrow><mrow><mi>T</mi></mrow></msub></math>-integrated yield of deuterons to protons, d/p, is found to increase with the charged-particle multiplicity, as observed in inelastic pp collisions at different centre-of-mass energies. The d/p ratios are reported in a wide range, from the lowest to the highest multiplicity values measured in pp collisions at the LHC.

B. Ali

D. Bauri

Multiplicity dependence of (anti-)deuteron production in pp collisions at

The pseudorapidity density of charged particles, $$\mathrm {d}N_{\mathrm{ch}}/\mathrm {d}\eta $$ <math><mrow><mi>d</mi><msub><mi>N</mi><mi>ch</mi></msub><mo>/</mo><mi>d</mi><mi>η</mi></mrow></math> , in p–Pb collisions has been measured at a centre-of-mass energy per nucleon–nucleon pair of $$\sqrt{s_{\scriptscriptstyle {\mathrm{NN}}}}$$ <math><msqrt><msub><mi>s</mi><mstyle><mi>NN</mi></mstyle></msub></msqrt></math>  = 8.16 TeV at mid-pseudorapidity for non-single-diffractive events. The results cover 3.6 units of pseudorapidity, $$|\eta |&lt;1.8$$ <math><mrow><mo>|</mo><mi>η</mi><mo>|</mo><mo>&lt;</mo><mn>1.8</mn></mrow></math> . The $$\mathrm {d}N_{\mathrm{ch}}/\mathrm {d}\eta $$ <math><mrow><mi>d</mi><msub><mi>N</mi><mi>ch</mi></msub><mo>/</mo><mi>d</mi><mi>η</mi></mrow></math>  value is $$19.1\pm 0.7$$ <math><mrow><mn>19.1</mn><mo>±</mo><mn>0.7</mn></mrow></math>  at $$|\eta |&lt;0.5$$ <math><mrow><mo>|</mo><mi>η</mi><mo>|</mo><mo>&lt;</mo><mn>0.5</mn></mrow></math> . This quantity divided by $$\langle N_{\mathrm{part}} \rangle $$ <math><mrow><mo>⟨</mo><msub><mi>N</mi><mi>part</mi></msub><mo>⟩</mo></mrow></math>  / 2 is $$4.73\pm 0.20$$ <math><mrow><mn>4.73</mn><mo>±</mo><mn>0.20</mn></mrow></math> , where $$\langle N_{\mathrm{part}} \rangle $$ <math><mrow><mo>⟨</mo><msub><mi>N</mi><mi>part</mi></msub><mo>⟩</mo></mrow></math> is the average number of participating nucleons, is 9.5% higher than the corresponding value for p–Pb collisions at $$\sqrt{s_{\scriptscriptstyle {\mathrm{NN}}}}$$ <math><msqrt><msub><mi>s</mi><mstyle><mi>NN</mi></mstyle></msub></msqrt></math>  = 5.02 TeV. Measurements are compared with models based on different mechanisms for particle production. All models agree within uncertainties with data in the Pb-going side, while HIJING overestimates, showing a symmetric behaviour, and EPOS underestimates the p-going side of the $$\mathrm {d}N_{\mathrm{ch}}/\mathrm {d}\eta $$ <math><mrow><mi>d</mi><msub><mi>N</mi><mi>ch</mi></msub><mo>/</mo><mi>d</mi><mi>η</mi></mrow></math>  distribution. Saturation-based models reproduce the distributions well for $$\eta &gt;-1.3$$ <math><mrow><mi>η</mi><mo>&gt;</mo><mo>-</mo><mn>1.3</mn></mrow></math> . The $$\mathrm {d}N_{\mathrm{ch}}/\mathrm {d}\eta $$ <math><mrow><mi>d</mi><msub><mi>N</mi><mi>ch</mi></msub><mo>/</mo><mi>d</mi><mi>η</mi></mrow></math>  is also measured for different centrality estimators, based both on the charged-particle multiplicity and on the energy deposited in the Zero-Degree Calorimeters. A study of the implications of the large multiplicity fluctuations due to the small number of participants for systems like p–Pb in the centrality calculation for multiplicity-based estimators is discussed, demonstrating the advantages of determining the centrality with energy deposited near beam rapidity.

S. Adhya

M. Aggarwal

G. Rinella

S. Ahn

S. Alam

D. Albuquerque

H. Alfanda

R. Molina

M. Anaam

H. Andrews

I. Arsene

M. Azmi

Y. Baek

R. Baral

G. Barnaföldi

L. Barnby

P. Batzing

J. Bazo Alba

I. Bearden

N. Behera

H. Martinez

L. Beltran

R. Bertens

I. Bhat

Charged-particle pseudorapidity density at mid-rapidity in p–Pb collisions at $$\pmb {\sqrt{s_{\scriptscriptstyle {\mathrm{NN}}}}}$$ <math><mrow><msqrt><msub><mi>s</mi><mstyle><mi>NN</mi></mstyle></msub></msqrt></mrow></math>  = 8.16 TeV

Inclusive ϒ(1S) and ϒ(2S) production have been measured in Pb–Pb collisions at the centre-of-mass energy per nucleon–nucleon pair <math><msqrt><mrow><msub><mrow><mi>s</mi></mrow><mrow><mi>NN</mi></mrow></msub></mrow></msqrt><mo>=</mo><mn>5.02</mn></math> TeV, using the ALICE detector at the CERN LHC. The ϒ mesons are reconstructed in the centre-of-mass rapidity interval <math><mn>2.5</mn><mo>&lt;</mo><mi>y</mi><mo>&lt;</mo><mn>4</mn></math> and in the transverse-momentum range <math><msub><mrow><mi>p</mi></mrow><mrow><mi>T</mi></mrow></msub><mo>&lt;</mo><mn>15</mn></math> GeV/c, via their decays to muon pairs. In this Letter, we present results on the inclusive ϒ(1S) nuclear modification factor <math><msub><mrow><mi>R</mi></mrow><mrow><mi>AA</mi></mrow></msub></math> as a function of collision centrality, transverse momentum and rapidity. The ϒ(1S) and ϒ(2S) <math><msub><mrow><mi>R</mi></mrow><mrow><mtext>AA</mtext></mrow></msub></math>, integrated over the centrality range 0–90%, are <math><mn>0.37</mn><mo>±</mo><mn>0.02</mn><mrow><mo>(</mo><mi>stat</mi><mo>)</mo></mrow><mo>±</mo><mn>0.03</mn><mrow><mo>(</mo><mi>syst</mi><mo>)</mo></mrow></math> and <math><mn>0.10</mn><mo>±</mo><mn>0.04</mn><mrow><mo>(</mo><mi>stat</mi><mo>)</mo></mrow><mo>±</mo><mn>0.02</mn><mrow><mo>(</mo><mi>syst</mi><mo>)</mo></mrow></math>, respectively, leading to a ratio <math><msubsup><mrow><mi>R</mi></mrow><mrow><mi>AA</mi></mrow><mrow><mi>ϒ</mi><mo>(</mo><mrow><mn>2S</mn></mrow><mo>)</mo></mrow></msubsup><mo>/</mo><msubsup><mrow><mi>R</mi></mrow><mrow><mi>AA</mi></mrow><mrow><mi>ϒ</mi><mo>(</mo><mrow><mn>1S</mn></mrow><mo>)</mo></mrow></msubsup></math> of <math><mn>0.28</mn><mo>±</mo><mn>0.12</mn><mtext>(stat)</mtext><mo>±</mo><mn>0.06</mn><mtext>(syst)</mtext></math>. The observed ϒ(1S) suppression increases with the centrality of the collision and no significant variation is observed as a function of transverse momentum and rapidity.

B. Audurier

ϒ suppression at forward rapidity in Pb–Pb collisions at

Azimuthally-differential femtoscopic measurements, being sensitive to spatio-temporal characteristics of the source as well as to the collective velocity fields at freeze out, provide very important information on the nature and dynamics of the system evolution. While the HBT radii oscillations relative to the second harmonic event plane measured recently reflect mostly the spatial geometry of the source, model studies have shown that the HBT radii oscillations relative to the third harmonic event plane are predominantly defined by the velocity fields. In this Letter, we present the first results on azimuthally-differential pion femtoscopy relative to the third harmonic event plane as a function of the pion pair transverse momentum <math><msub><mrow><mi>k</mi></mrow><mrow><mi>T</mi></mrow></msub></math> for different collision centralities in Pb–Pb collisions at <math><msqrt><mrow><msub><mrow><mi>s</mi></mrow><mrow><mi>NN</mi></mrow></msub></mrow></msqrt><mo>=</mo><mn>2.76</mn><mtext> TeV</mtext></math>. We find that the <math><msub><mrow><mi>R</mi></mrow><mrow><mi>side</mi></mrow></msub></math> and <math><msub><mrow><mi>R</mi></mrow><mrow><mi>out</mi></mrow></msub></math> radii, which characterize the pion source size in the directions perpendicular and parallel to the pion transverse momentum, oscillate in phase relative to the third harmonic event plane, similar to the results from 3+1D hydrodynamical calculations. The observed radii oscillations unambiguously signal a collective expansion and anisotropy in the velocity fields. A comparison of the measured radii oscillations with the Blast-Wave model calculations indicate that the initial state triangularity is washed-out at freeze out.

J. Bielčíková

A. Bilandzic

Azimuthally-differential pion femtoscopy relative to the third harmonic event plane in Pb–Pb collisions at

$$\phi $$ <math><mi>ϕ</mi></math>  meson measurements provide insight into strangeness production, which is one of the key observables for the hot medium formed in high-energy heavy-ion collisions. ALICE measured $$\phi $$ <math><mi>ϕ</mi></math>  production through its decay in muon pairs in Pb–Pb collisions at $$\sqrt{s_\mathrm {NN}} = 2.76$$ <math><mrow><msqrt><msub><mi>s</mi><mi>NN</mi></msub></msqrt><mo>=</mo><mn>2.76</mn></mrow></math>  TeV in the intermediate transverse momentum range $$2&lt; p_\mathrm {T}&lt; 5$$ <math><mrow><mn>2</mn><mo>&lt;</mo><msub><mi>p</mi><mi>T</mi></msub><mo>&lt;</mo><mn>5</mn></mrow></math>  GeV/c and in the rapidity interval $$2.5&lt;y&lt;4$$ <math><mrow><mn>2.5</mn><mo>&lt;</mo><mi>y</mi><mo>&lt;</mo><mn>4</mn></mrow></math> . The $$\phi $$ <math><mi>ϕ</mi></math>  yield was measured as a function of the transverse momentum and collision centrality. The nuclear modification factor was obtained as a function of the average number of participating nucleons. Results were compared with the ones obtained via the kaon decay channel in the same $$p_\mathrm {T}$$ <math><msub><mi>p</mi><mi>T</mi></msub></math>  range at midrapidity. The values of the nuclear modification factor in the two rapidity regions are in agreement within uncertainties.

O. Arnold

A. Barbano

P. Bhaduri

C. Bianchin

$$\phi $$ <math><mi>ϕ</mi></math>  meson production at forward rapidity in Pb–Pb collisions at $$\sqrt{s_\mathrm {NN}}=2.76$$ <math><mrow><msqrt><msub><mi>s</mi><mi>NN</mi></msub></msqrt><mo>=</mo><mn>2.76</mn></mrow></math>  TeV

The first measurements of anisotropic flow coefficients <math><msub><mrow><mi>v</mi></mrow><mrow><mi>n</mi></mrow></msub></math> for mid-rapidity charged particles in Xe–Xe collisions at <math><msqrt><mrow><msub><mrow><mi>s</mi></mrow><mrow><mi>NN</mi></mrow></msub></mrow></msqrt><mo>=</mo><mn>5.44</mn></math> TeV are presented. Comparing these measurements to those from Pb–Pb collisions at <math><msqrt><mrow><msub><mrow><mi>s</mi></mrow><mrow><mi>NN</mi></mrow></msub></mrow></msqrt><mo>=</mo><mn>5.02</mn></math> TeV, <math><msub><mrow><mi>v</mi></mrow><mrow><mn>2</mn></mrow></msub></math> is found to be suppressed for mid-central collisions at the same centrality, and enhanced for central collisions. The values of <math><msub><mrow><mi>v</mi></mrow><mrow><mn>3</mn></mrow></msub></math> are generally larger in Xe–Xe than in Pb–Pb at a given centrality. These observations are consistent with expectations from hydrodynamic predictions. When both <math><msub><mrow><mi>v</mi></mrow><mrow><mn>2</mn></mrow></msub></math> and <math><msub><mrow><mi>v</mi></mrow><mrow><mn>3</mn></mrow></msub></math> are divided by their corresponding eccentricities for a variety of initial state models, they generally scale with transverse density when comparing Xe–Xe and Pb–Pb, with some deviations observed in central Xe–Xe and Pb–Pb collisions. These results assist in placing strong constraints on both the initial state geometry and medium response for relativistic heavy-ion collisions.

Anisotropic flow in Xe–Xe collisions at TeV