Probing the topological charge in QCD matter via multiplicity up–down asymmetry

Sun, Yifeng; Ko, Che Ming

doi:10.1016/j.physletb.2018.12.042

Cited by 3 publications

(2 citation statements)

References 55 publications

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“…The ultrarelativistic heavy ion collisions (uRHICs) at both the BNL Relativistic Heavy Ion Collider (RHIC) [1,2] and the CERN Large Hadron Collider (LHC) [3] have created a new state of matter, the quark-gluon plasma (QGP), during their early stage and showed that such a matter is the most perfect fluid in nature [4][5][6]. In the last decades, there are numerous studies in the search for the parity (P) and charge conjugate parity (C P) symmetry breaking processes in quantum chromodynamics (QCD) happened in QGP, mainly via the chiral magnetic effect (CME) [7][8][9][10][11][12] and the chiral vortical effect (CVE) [13]. The strongest ever electromagnetic (e.m.) field and the largest relativistic vorticity [14,15] are created in a e-mail: sunyfphy@lns.infn.it (corresponding author) b e-mail: greco@lns.infn.it c e-mail: salvatore.plumari@ct.infn.it 0123456789().…”

Section: Introductionmentioning

confidence: 99%

The signature of charge dependent directed flow observables by electromagnetic fields in heavy ion collisions

2021

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We discuss the generation of the directed flow $$v_1(p_T,y_z)$$ v 1 ( p T , y z ) induced by the electromagnetic field as a function of $$p_T$$ p T and $$y_z$$ y z . Despite the complex dynamics of charged particles due to strong interactions generating several anisotropies in the azimuthal angle, it is possible at $$p_T > m$$ p T > m to directly correlate the splitting in $$v_1$$ v 1 of heavy quarks with different charges to some main features of the magnetic field, and in particular its values at formation and freeze-out time. We further found that the slope of the splitting $$d\Delta v_1/dy_z|_{y_z=0}$$ d Δ v 1 / d y z | y z = 0 of positively and negatively charged particles at high $$p_T$$ p T can be formulated as $$d\Delta v_1/dy_z|_{y_z=0}=-\alpha \frac{\partial \ln f}{\partial p_T}+\frac{2\alpha -\beta }{p_T}$$ d Δ v 1 / d y z | y z = 0 = - α ∂ ln f ∂ p T + 2 α - β p T , where f is the $$p_T$$ p T spectra of the charged particles and the constants $$\alpha $$ α and $$\beta $$ β (order of MeV) are constrained by the y component of magnetic fields and the sign of $$\alpha $$ α is simply determined by the difference $$\Delta [tB_y(t)]$$ Δ [ t B y ( t ) ] in the center of colliding systems at the formation time of particles and at the time when particles leave the effective range of electromagnetic fields or freeze out. The formula is derived from general considerations and is confirmed by several related numerical simulations; it supplies a useful guide to quantify the effect of different magnetic field configurations and provides an evidence of why the measurement of $$\Delta v_1$$ Δ v 1 of charm, bottom and leptons from $$Z^0$$ Z 0 decay and their correlations are a powerful probe of the initial e.m. fields in ultra-relativistic collisions.

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Section: Introductionmentioning

confidence: 99%

The signature of charge dependent directed flow observables by electromagnetic fields in heavy ion collisions

2021

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“…The ultrarelativistic heavy ion collisions (uRHICs) at both the BNL Relativistic Heavy Ion Collider (RHIC) [1,2] and the CERN Large Hadron Collider (LHC) [3] have created a new state of matter, the quark-gluon plasma (QGP), during their early stage and showed that such a matter is the most perfect fluid in nature [4][5][6]. In the last decades, there are numerous studies in the search for the parity (P ) and charge conjugate parity (CP ) symmetry breaking processes in quantum chromodynamics (QCD) happened in QGP, mainly via the chiral magnetic effect (CME) [7][8][9][10][11][12] and the chiral vortical effect (CVE) [13]. The strongest ever electromagnetic (e.m.) field and the largest relativistic vorticity [14,15] are created in noncentral heavy ion collisions.…”

Section: Introductionmentioning

confidence: 99%

The signature of charge dependent directed flow observables by electromagnetic fields in heavy ion collisions

Sun,

Greco,

Plumari

2021

Preprint

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We discuss the generation of the directed flow v1(pT , yz) induced by the electromagnetic field as a function of pT and yz. Despite the complex dynamics of charged particles due to strong interactions generating several anisotropies in the azimuthal angle, it is possible at pT > m to directly correlate the splitting in v1 of heavy quarks with different charges to some main features of the magnetic field, and in particular its values at formation and freeze-out time.We further found that the splitting d∆v1/dyz|y z =0 of positively and negatively charged particles at high pT can be formulated as d∆v1/dyz|y z =0 = −α ∂ ln f ∂p T + 2α−β p T , where the constants α and β are constrained by the y component of magnetic fields and the sign of α is simply determined by the difference ∆[tBy(t)] in the center of colliding systems at the formation time of particles and at the time when particles leave the effective range of electromagnetic fields or freeze out. The formula is derived from general considerations and is confirmed by several related numerical simulations; it supplies a useful guide to quantify the effect of different magnetic field configurations and provides an evidence of why the measurement of ∆v1 of charm, bottom and leptons from Z 0 decay and their correlations are a powerful probe of the initial e.m. fields in ultra-relativistic collisions.

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Azimuthal angle dependence of the longitudinal spin polarization in relativistic heavy ion collisions

Sun

2019

Phys. Rev. C

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The azimuthal angle dependence of quark spin polarization in the longitudinal beam direction of non-central relativistic heavy ion collisions is studied in the chiral kinetic approach. Contrary to the prediction from models based on the assumption of thermal equilibrium of spin degrees of freedom that the quark spin polarization always points along the direction of local vorticity field, we find the two can have opposite directions due to the effect from the transversal component of vorticity field, which can lead to a redistribution of axial charges in the produced matter. Our finding is consistent with the azimuthal angle dependence of the longitudinal spin polarization of Λ hyperons, which is mainly determined by that of the strange quark, recently measured in the experiments by the STAR Collaboration at the Relativistic Heavy Ion Collider (RHIC).

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Probing the topological charge in QCD matter via multiplicity up–down asymmetry

Cited by 3 publications

References 55 publications

The signature of charge dependent directed flow observables by electromagnetic fields in heavy ion collisions

The signature of charge dependent directed flow observables by electromagnetic fields in heavy ion collisions

The signature of charge dependent directed flow observables by electromagnetic fields in heavy ion collisions

Azimuthal angle dependence of the longitudinal spin polarization in relativistic heavy ion collisions

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