We present ratios of the numbers of charged antiparticles to particles (pions, kaons and protons) in Au + Au collisions at $\sqrt{s_{NN}}=200$ GeV as a function of rapidity in the range $y$=0-3. While the particle ratios at midrapidity are approaching unity, the $K^-/K^+$ and $\bar{p}/p$ ratios decrease significantly at forward rapidities. An interpretation of the results within the statistical model indicates a reduction of the baryon chemical potential from $\mu_B \approx 130$MeV at $y$=3 to $\mu_B \approx 25$MeV at $y$=0.

Measurements, with the BRAHMS detector, of the antiproton to proton ratio at central and forward rapidities are presented for Au+Au reactions at sqrt{s_{NN}}=130 GeV, and for three different collision centralities. For collisions in the 0-40% centrality range we find $N(\bar{{\rm p}})/N({\rm p}) = 0.64 +- 0.04 (stat.) +- 0.06 (syst.) at y ~0, 0.66 +- 0.03 +- 0.06 at y ~ 0.7, and 0.41 +- 0.04 +- 0.06 at y ~ 2. The ratios are found to be nearly independent of collision centrality and transverse momentum. The measurements demonstrate that the antiproton and proton rapidity densities vary differently with rapidity, and indicate that a net-baryon free midrapidity plateau (Bjorken limit) is not reached at this RHIC energy.

The BRAHMS collaboration has measured transverse momentum spectra of pions, kaons, protons and antiprotons at rapidities 0 and 3 for Cu+Cu collisions at $\sqrt{s_{NN}} = 200$ GeV. As the collisions become more central the collective radial flow increases while the temperature of kinetic freeze-out decreases. The temperature is lower and the radial flow weaker at forward rapidity. Pion and kaon yields with transverse momenta between 1.5 and 2.5 GeV/c are suppressed for central collisions relative to scaled $p+p$ collisions. This suppression, which increases as the collisions become more central is consistent with jet quenching models and is also present with comparable magnitude at forward rapidity. At such rapidities initial state effects may also be present and persistence of the meson suppression to high rapidity may reflect a combination of jet quenching and nuclear shadowing. The ratio of protons to mesons increases as the collisions become more central and is largest at forward rapidities.

The proton-to-pion ratios measured in the BRAHMS experiment for Au+Au and p+p collisions at $\sqrt{s_{NN}}$ = 62.4 and 200 GeV are presented as a function of transverse momentum and collision centrality at selected pseudorapidities in the range of 0 to 3.8. A strong pseudorapidity dependence of these ratios is observed. We also compare the magnitude and p_T-dependence of the p/pi ratios measured in Au+Au collisions at \rootsnn{200} and $\eta \approx 2.2$ with the same ratio measured at \rootsnn{62.4} and $\eta = 0$. The great similarity found between these ratios throughout the whole p_T range (up to 2.2 GeV/$c$) is consistent with particle ratios in A+A collisions being described with grand-canonical distributions characterized by the baryo-chemical potential \mibn. At the collision energy of 62.4 GeV, we have observed a unique point in pseudorapidity, $\eta = 3.2$, where the p/pi+ ratio is independent of the collision system size in a wide p_T-range of $0.3 \le p_{T} \le 1.8$ GeV/$c$.

The production of the $\psi(2S)$ charmonium state was measured with ALICE in Pb-Pb collisions at $\sqrt{s_{\rm NN}}=5.02$ TeV, in the dimuon decay channel. A significant signal was observed for the first time at LHC energies down to zero transverse momentum, at forward rapidity ($2.5<y<4$). The measurement of the ratio of the inclusive production cross sections of the $\psi(2S)$ and J/$\psi$ resonances is reported as a function of the centrality of the collisions and of transverse momentum, in the region $p_{\rm T}<12$ GeV/$c$. The results are compared with the corresponding measurements in pp collisions, by forming the double ratio $[\sigma^{\psi(2S)}/\sigma^{J/\psi}]_{\rm{Pb-Pb}}/[\sigma^{\psi(2S)}/\sigma^{J/\psi}]_{\rm{pp}}$. It is found that in Pb-Pb collisions the $\psi(2S)$ is suppressed by a factor of $\sim 2$ with respect to the J/$\psi$. The $\psi(2S)$ nuclear modification factor $R_{\rm AA}$ was also obtained as a function of both centrality and $p_{\rm T}$. The results show that the $\psi(2S)$ resonance yield is strongly suppressed in Pb-Pb collisions, by a factor up to $\sim 3$ with respect to pp. Comparisons of cross section ratios with previous SPS findings by the NA50 experiment and of $R_{\rm AA}$ with higher-$p_{\rm T}$ results at LHC energy are also reported. These results and the corresponding comparisons with calculations of transport and statistical models address questions on the presence and properties of charmonium states in the quark-gluon plasma formed in nuclear collisions at the LHC.

The production cross sections of the prompt charmed mesons D$^0$, D$^+$, D$^{*+}$ and D$_s$ were measured at mid-rapidity in p-Pb collisions at a centre-of-mass energy per nucleon pair $\sqrt{s_{\rm NN}}=5.02$ TeV with the ALICE detector at the LHC. D mesons were reconstructed from their decays D$^0\rightarrow{\rm K}^-\pi^+$, D$^+\rightarrow{\rm K}^-\pi^+\pi^+$, D$^{*+}\rightarrow D^0\pi^+$, D$_s^+\rightarrow\phi\pi^+\rightarrow{\rm K}^-{\rm K}^+\pi^+$, and their charge conjugates. The $p_{\rm T}$-differential production cross sections were measured at mid-rapidity in the interval $1<p_{\rm T}<24$ GeV/$c$ for D$^0$, D$^+$ and D$^{*+}$ mesons and in $2<p_{\rm T}<12$ GeV/$c$ for D$_s$ mesons, using an analysis method based on the selection of decay topologies displaced from the interaction vertex. The production cross sections of the D$^0$, D$^+$ and D$^{*+}$ mesons were also measured in three $p_{\rm T}$ intervals as a function of the rapidity $y_{\rm cms}$ in the centre-of-mass system in $-1.26<y_{\rm cms}<0.34$. In addition, the prompt D$^0$ cross section was measured in pp collisions at $\sqrt{s}=7$ TeV and p-Pb collisions at $\sqrt{s_{\rm NN}}=5.02$ TeV down to $p_{\rm T}=0$ using an analysis technique that is based on the estimation and subtraction of the combinatorial background, without reconstruction of the D$^0$ decay vertex. The nuclear modification factor $R_{\rm pPb}(p_{\rm T})$, defined as the ratio of the $p_{\rm T}$-differential D-meson cross section in p-Pb collisions and that in pp collisions scaled by the mass number of the Pb nucleus, was calculated for the four D-meson species and found to be compatible with unity within experimental uncertainties. The results are compared to theoretical calculations that include cold-nuclear-matter effects and to transport model calculations incorporating the interactions of charm quarks with an expanding deconfined medium.

The production of the W$^\pm$ bosons measured in p$-$Pb collisions at a centre-of-mass energy per nucleon$-$nucleon collision $\sqrt{s_{NN}} = 8.16$ TeV and Pb$-$Pb collisions at $\sqrt{s_{NN}} = 5.02$ TeV with ALICE at the LHC is presented. The W$^\pm$ bosons are measured via their muonic decay channel, with the muon reconstructed in the pseudorapidity region $-4 < \eta^\mu_{\rm lab} < -2.5$ with transverse momentum $p_{\rm T}^\mu > 10$ GeV/$c$. While in Pb$-$Pb collisions the measurements are performed in the forward ($2.5 < y^\mu_{\rm cms} < 4$) rapidity region, in p$-$Pb collisions, where the centre-of-mass frame is boosted with respect to the laboratory frame, the measurements are performed in the backward ($-4.46 < y^\mu_{\rm cms} < -2.96$) and forward ($2.03 < y^\mu_{\rm cms} < 3.53$) rapidity regions. The W$^{-}$ and W$^{+}$ production cross sections, lepton-charge asymmetry, and nuclear modification factors are evaluated as a function of the muon rapidity. In order to study the production as a function of the p$-$Pb collision centrality, the production cross sections of the W$^{-}$ and W$^{+}$ bosons are combined and normalised to the average number of binary nucleon$-$nucleon collision $\langle N_\mathrm{coll} \rangle$. In Pb$-$Pb collisions, the same measurements are presented as a function of the collision centrality. Study of the binary scaling of the W$^\pm$-boson cross sections in p$-$Pb and Pb$-$Pb collisions is also reported. The results are compared with perturbative QCD (pQCD) calculations, with and without nuclear modifications of the Parton Distribution Functions (PDFs), as well as with available data at the LHC. Significant deviations from the theory expectations are found in the two collision systems, indicating that the measurements can provide additional constraints for the determination of nuclear PDF (nPDFs) and in particular of the light-quark distributions.

We report the first measurement of the net-charge fluctuations in Pb-Pb collisions at $\sqrt{s_{\rm NN}}$ = 2.76 TeV, measured with the ALICE detector at the CERN Large Hadron Collider. The dynamical fluctuations per unit entropy are observed to decrease when going from peripheral to central collisions. An additional reduction in the amount of fluctuations is seen in comparison to the results from lower energies. We examine the dependence of fluctuations on the pseudorapidity interval, which may account for the dilution of fluctuations during the evolution of the system. We find that the fluctuations at LHC are smaller compared to the measurements at the Relativistic heavy Ion Collider (RHIC), and as such, closer to what has been theoretically predicted for the formation of Quark-Gluon Plasma (QGP).

We have studied J/psi production in pp collisions at $\sqrt{s}=7$ TeV at the LHC through its muon pair decay. The polar and azimuthal angle distributions of the decay muons were measured, and results on the J/$\psi$ polarization parameters $\lambda_{\theta}$ and $\lambda_\phi$ were obtained. The study was performed in the kinematic region 2.5<y<4, 2<$p_{\rm T}$<8 GeV/$c$, in the helicity and Collins-Soper reference frames. In both frames, the polarization parameters are compatible with zero, within uncertainties.

The first measurement of e$^+$e$^-$ pair production at mid-rapidity ($|\eta_{{\rm e}}|$ $<$ 0.8) in pp collisions at $\sqrt{s} = 7$ TeV with ALICE at the LHC is presented. The dielectron production is studied as a function of the invariant mass ($m_{\rm ee}$ $<$ 3.3 GeV/$c^{2}$), the pair transverse momentum ($p_{\rm T,ee}$ $<$ 8 GeV/$c$), and the pair transverse impact parameter (DCA$_{{\rm ee}}$), i.e., the average distance of closest approach of the reconstructed electron and positron tracks to the collision vertex, normalised to its resolution. The results are compared with the expectations from a cocktail of known hadronic sources and are well described when PYTHIA is used to generate the heavy-flavour contributions. In the low-mass region (0.14 $<$ $m_{\rm ee}$ $<$ 1.1 GeV/$c^{2}$), prompt and non-prompt e$^+$e$^-$ sources can be separated via the DCA$_{\rm ee}$. In the intermediate-mass region (1.1 $<$ $m_{\rm ee}$ $<$ 2.7 GeV/$c^{2}$), a double-differential fit to the data in $m_{\rm ee}$ and $p_{\rm T,ee}$ and a fit of the DCA$_{\rm ee}$ distribution allow the total ${\rm c\overline c}$ and ${\rm b\overline b}$ cross sections to be extracted. Two different event generators, PYTHIA and POWHEG, can reproduce the shape of the two-dimensional $m_{\rm ee}$ and $p_{\rm T,ee}$ spectra, as well as the shape of the DCA$_{\rm ee}$ distribution, reasonably well. However, differences in the ${\rm c\overline c}$ and ${\rm b\overline b}$ cross sections are observed when using the generators to extrapolate to full phase space. Finally, the ratio of inclusive to decay photons is studied via the measurement of virtual direct photons in the transverse-momentum range 1 $<$ $p_{\rm T}$ $<$ 8 GeV/$c$. This is found to be unity within the statistical and systematic uncertainties and consistent with expectations from next-to-leading order perturbative quantum chromodynamic calculations.