Role of QCD monopoles in jet quenching

QCD monopoles are magnetically charged quasiparticles whose Bose-Einstein condensation (BEC) at $T<T_c$ creates electric confinement and flux tubes. The “magnetic scenario” of QCD proposes that scattering on the noncondensed component of the monopole ensemble at $T>T_c$ is responsible for the unusual kinetic properties of quark-gluon plasma. In this paper, we study the contribution of the monopoles to jet quenching phenomenon, using the Baier-Dokshitzer-Mueller-Peigne-Schiff framework and hydrodynamic backgrounds. In the lowest order for cross sections, we calculate the nuclear modification factor, $R_{\mathrm{AA}}$, and azimuthal anisotropy, $v_2$, of jets, as well as the dijet asymmetry, $A_j$, and compare those to the available data. We find relatively good agreement with experiment when using realistic hydrodynamic backgrounds. In addition, we find that event-by-event fluctuations are not necessary to reproduce $R_{\mathrm{AA}}$ and $v_2$ data, but play a role in $A_j$. Since the monopole-induced effects are maximal at $T\approx T_c$, we predict that their role should be significantly larger, relative to quarks and gluons, at lower RHIC energies.

Figure 1

Electric and magnetic quasiparticle densities used. The (blue) solid line shows the magnetic monopole density as directly observed on the lattice. The (red) long dashed line is the monopole density extracted from the thermodynamics (pressure), along with the densities of quarks (purple, short dashed) and gluons (green, dot dashed).

Figure 2

Ratio of correlated to uncorrelated average momentum transfer square per mean free path as a function of the temperature.

Figure 3

Temperature profile of 20%–30% centrality (a) 2.76 TeV Pb-Pb and (b) 200 GeV Au-Au collisions calculated using the energy density profile at $\tau =0.2\mathrm{fm}/\mathrm{c}$ from Ref. [28] and equation of state from Ref. [26].

Figure 4

Temperature profile of a 20%–30% centrality 2.76 TeV Pb-Pb collision, shown at various times of the hydrodynamic evolution. This evolution was done using IP-Glasma initial conditions and $(2+1)\mathrm{D}$ hydrodynamics with bulk viscosity.

Figure 5

Ratio of energy loss to initial parton jet energy in 2.76 Pb-Pb collisions (a),(b), and 200 GeV Au-Au collisions (c),(d). The first row (a),(c) is the results for monopole density from the lattice, while the second row (b),(d) is results for monopole density from the equation of state. The (red) solid curve is for IP-Glasma initial conditions and $(2+1)\mathrm{D}$ hydrodynamics with bulk viscosity ($\zeta \ne 0$), the (blue) dash-dot curve is for Glauber initial conditions and $(2+1)\mathrm{D}$ hydrodynamics with bulk viscosity ($\zeta \ne 0$), the (green) dash-dot-dot curve is for Glauber initial conditions and $(2+1)\mathrm{D}$ hydrodynamics without bulk viscosity ($\zeta =0$), and the (purple) dashed curve is for the smooth Glauber initial condition with $(1+1)\mathrm{D}$ Bjorken evolution.

Figure 6

Nuclear modification factor of charged hadrons in 2.76 Pb-Pb collisions (a),(b), and neutral pions in 200 GeV Au-Au collisions (c),(d). The first row (a),(c) is the results for monopole density from the lattice, while the second row (b),(d) is results for monopole density from the equation of state. The (red) solid curve is for IP-Glasma initial conditions and $(2+1)\mathrm{D}$ hydrodynamics with bulk viscosity ($\zeta \ne 0$), the (blue) dash-dot curve is for Glauber initial conditions and $(2+1)\mathrm{D}$ hydrodynamics with bulk viscosity ($\zeta \ne 0$), the (green) dash-dot-dot curve is for Glauber initial conditions and $(2+1)\mathrm{D}$ hydrodynamics without bulk viscosity ($\zeta =0$), and the (purple) dashed curve is for the smooth Glauber initial condition with $(1+1)\mathrm{D}$ Bjorken evolution. Collider data from Refs. [35, 36] for LHC and Refs. [37, 38] for RHIC.

Figure 7

Azimuthal anisotropy of charged hadrons in 2.76 Pb-Pb collisions (a),(b), and neutral pions in 200 GeV Au-Au collisions (c),(d). The first row (a),(c) is the results for monopole density from the lattice, while the second row (b),(d) is results for monopole density from the equation of state. The (red) solid curve is for IP-Glasma initial conditions and $(2+1)\mathrm{D}$ hydrodynamics with bulk viscosity ($\zeta \ne 0$), the (blue) dash-dot curve is for Glauber initial conditions and $(2+1)\mathrm{D}$ hydrodynamics with bulk viscosity ($\zeta \ne 0$), the (green) dash-dot-dot curve is for Glauber initial conditions and $(2+1)\mathrm{D}$ hydrodynamics without bulk viscosity ($\zeta =0$), and the (purple) dashed curve is for the smooth Glauber initial condition with $(1+1)\mathrm{D}$ Bjorken evolution. The (black) dotted curve is for IP-Glasma initial conditions and $(2+1)\mathrm{D}$ hydrodynamics with bulk viscosity ($\zeta \ne 0$) with no monopoles. Collider data from Refs. [39, 40] for the LHC and Ref. [41] for RHIC.

Figure 8

Dijet asymmetry of parton jets in 2.76 Pb-Pb collisions (a),(b), and 200 GeV Au-Au collisions (c),(d). The first row (a),(c) is the results for monopole density from the lattice, while the second row (b),(d) is results for monopole density from the equation of state. The (red) solid curve is for IP-Glasma initial conditions and $(2+1)\mathrm{D}$ hydrodynamics with bulk viscosity ($\zeta \ne 0$), the (blue) dash-dot curve is for Glauber initial conditions and $(2+1)\mathrm{D}$ hydrodynamics with bulk viscosity ($\zeta \ne 0$), the (green) dash-dot-dot curve is for Glauber initial conditions and $(2+1)\mathrm{D}$ hydrodynamics without bulk viscosity ($\zeta =0$), and the (purple) dashed curve is for the smooth Glauber initial condition with $(1+1)\mathrm{D}$ Bjorken evolution. Collider data from Ref. [42].

Figure 9

Dijet asymmetry of parton jets with no $p_{\perp }$ cut (red, solid curve), $p_{\perp }>16\mathrm{GeV}$ (blue, dashed curve), and $p_{\perp }>24\mathrm{GeV}$ (green, dot-dashed curve) in 2.76 Pb-Pb collisions for the IP-Glasma initial conditions with $(2+1)\mathrm{D}$ hydrodynamics with bulk viscosity and monopole density given by the lattice. Collider data from Ref. [42].

Figure 10

Dijet asymmetry of parton jets originating in the center of the fireball in 2.76 Pb-Pb collisions with the monopole density from the lattice. The (red) solid curve is for IP-Glasma initial conditions and $(2+1)\mathrm{D}$ hydrodynamics with bulk viscosity ($\zeta \ne 0$), the (blue) dash-dot curve is for Glauber initial conditions and $(2+1)\mathrm{D}$ hydrodynamics with bulk viscosity ($\zeta \ne 0$), the (green) dash-dot-dot curve is for Glauber initial conditions and $(2+1)\mathrm{D}$ hydrodynamics without bulk viscosity ($\zeta =0$), and the (purple) dashed curve is for the smooth Glauber initial condition with $(1+1)\mathrm{D}$ Bjorken evolution. Collider data from Ref. [42].

Figure 11

Nuclear modification factor of neutral pions for 62.4 GeV Au-Au collisions. The (blue) solid curve is the result for monopole density from the lattice, and the (red) dashed curve is the result for monopole density from thermodynamics.

Figure 12

Azimuthal anisotropy of neutral pions for 62.4 GeV Au-Au collisions. The (blue) solid curve is the result for monopole density from the lattice, and the (red) dashed curve is the result for monopole density from thermodynamics.

Figure 13

Dijet asymmetry of parton jets for 62.4 GeV Au-Au collisions. The (blue) solid curve is the result for monopole density from the lattice, and the (red) dashed curve is the result for monopole density from thermodynamics.

Figure 14

The effect of monopole correlations on the nuclear modification factor of charged hadrons in 2.76 Pb-Pb collisions (a),(b), and neutral pions in 200 GeV Au-Au collisions (c),(d). The first row (a),(c) is the results for monopole density from the lattice, while the second row (b),(d) is results for monopole density from the equation of state. The (red) solid curve is for IP-Glasma initial conditions and $(2+1)\mathrm{D}$ hydrodynamics with bulk viscosity ($\zeta \ne 0$), the (blue) dash-dot curve is for Glauber initial conditions and $(2+1)\mathrm{D}$ hydrodynamics with bulk viscosity ($\zeta \ne 0$), the (green) dash-dot-dot curve is for Glauber initial conditions and $(2+1)\mathrm{D}$ hydrodynamics without bulk viscosity ($\zeta =0$), and the (purple) dashed curve is for the smooth Glauber initial condition with $(1+1)\mathrm{D}$ Bjorken evolution.

Figure 15

The effect of monopole correlations on the azimuthal anisotropy of charged hadrons in 2.76 Pb-Pb collisions (a),(b), and neutral pions in 200 GeV Au-Au collisions (c),(d). The first row (a),(c) is the results for monopole density from the lattice, while the second row (b),(d) is results for monopole density from the equation of state. The (red) solid curve is for IP-Glasma initial conditions and $(2+1)\mathrm{D}$ hydrodynamics with bulk viscosity ($\zeta \ne 0$), the (blue) dash-dot curve is for Glauber initial conditions and $(2+1)\mathrm{D}$ hydrodynamics with bulk viscosity ($\zeta \ne 0$), the (green) dash-dot-dot curve is for Glauber initial conditions and $(2+1)\mathrm{D}$ hydrodynamics without bulk viscosity ($\zeta =0$), and the (purple) dashed curve is for the smooth Glauber initial condition with $(1+1)\mathrm{D}$ Bjorken evolution.