May 13 – 19, 2018
Venice, Italy
Europe/Zurich timezone
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Spin alignment measurements using vector mesons with ALICE detector at the LHC

May 15, 2018, 9:20 AM
Sala Mosaici-2, 3rd Floor (Palazzo del Casinò)

Sala Mosaici-2, 3rd Floor

Palazzo del Casinò

Parallel Talk Chirality, vorticity and polarisation effects Chirality, vorticity and polarisation effects


Dr Ranbir Singh (NISER, Jatni, India)


Large magnetic field and large angular momentum are expected to be present in the initial stages of high-energy heavy-ion collisions. One of the physics interests of the heavy-ion program using the ALICE detector at the LHC is to look for signatures of these effects. This can be achieved by studying the angular distributions of the decay daughters of hyperons and vector mesons.

We present new measurements related to spin alignment of K$^{*0}$ vector mesons at mid-rapidity for Pb-Pb collisions at $\sqrt{s_{\mathrm{NN}}}$ = 2.76 and 5.02 TeV. The zeroth element of the spin density matrix element, $\rho_{00}$, is found to have values slightly below 1/3 at low transverse momentum ($p_{\mathrm{T}}$) for K$^{*0}$ mesons, while it is consistent with 1/3 (no spin alignment) at higher $p_{\mathrm{T}}$. No spin alignment is observed for K$^{*0}$ in pp collisions at $\sqrt{s}$ = 13 TeV and for the spin zero hadron K$^{0}_{S}$ in 20-40$\%$ Pb-Pb collisions at $\sqrt{s_{\mathrm{NN}}}$ = 2.76 TeV.
The $\rho_{00}$ values are not only sensitive to the angular momentum of the system but also to
the production mechanism of the vector meson. The centrality dependence of the $\rho_{00}$ results
with production plane and event plane in Pb--Pb collisions at LHC energies will be discussed in detail.

Content type Experiment
Collaboration ALICE
Centralised submission by Collaboration Presenter name already specified

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