A
bstract
We compute the next-to-leading order impact factor for inclusive dijet production in deeply inelastic electron-nucleus scattering at small
x
Bj
. Our computation, performed in the framework ...of the Color Glass Condensate effective field theory, includes all real and virtual contributions in the gluon shock wave background of all-twist lightlike Wilson line correlators. We demonstrate explicitly that the rapidity evolution of these correlators, to leading logarithmic accuracy, is described by the JIMWLK Hamiltonian. When combined with the next-to-leading order JIMWLK Hamiltonian, our results for the impact factor improve the accuracy of the inclusive dijet cross-section to
O
(
α
s
2
ln(
x
f
/x
Bj
)), where
x
f
is a rapidity factorization scale. These results are an essential ingredient in assessing the discovery potential of inclusive dijets to uncover the physics of gluon saturation at the Electron-Ion Collider.
In previous work, we outlined a worldline framework that can be used for systematic computations of the chiral magnetic effect (CME) in ultrarelativistic heavy-ion collisions. Towards this end, we ...first expressed the real part of the fermion determinant in the QCD effective action as a supersymmetric worldline action of spinning, colored, Grassmanian point particles in background gauge fields, with equations of motion that are covariant generalizations of the Bargmann-Michel-Telegdi and Wong equations. The chiral anomaly, in contrast, arises from the phase of the fermion determinant. Remarkably, the latter too can be expressed as a point particle worldline path integral, which can be employed to derive the anomalous axial vector current. We will show here how Berry’s phase can be obtained in a consistent nonrelativistic adiabatic limit of the real part of the fermion determinant. Our work provides a general first principles demonstration that the topology of Berry’s phase is distinct from that of the chiral anomaly confirming prior arguments by Fujikawa in specific contexts. This suggests that chiral kinetic treatments of the CME in heavy-ion collisions that include Berry’s phase alone are incomplete. We outline the elements of a worldline covariant relativistic chiral kinetic theory that captures the physics of how the chiral current is modified by many-body scattering and topological fluctuations.
We discuss a novel worldline framework for computations of the chiral magnetic effect (CME) in ultrarelativistic heavy-ion collisions. Starting from the fermion determinant in the QCD effective ...action, we show explicitly how its real part can be expressed as a supersymmetric worldline action of spinning, colored, Grassmannian particles in background fields. Restricting ourselves for simplicity to spinning particles, we demonstrate how their constrained Hamiltonian dynamics arises for both massless and massive particles. In a semiclassical limit, this gives rise to the covariant generalization of the Bargmann-Michel-Telegdi equation; the derivation of the corresponding Wong equations for colored particles is straightforward. In a previous paper N. Mueller and R. Venugopalan, arXiv:1701.03331., we outlined how Berry’s phase arises in a nonrelativistic adiabatic limit for massive particles. We extend the discussion here to systems with a finite chemical potential. We discuss a path integral formulation of the relative phase in the fermion determinant that places it on the same footing as the real part. We construct the corresponding anomalous worldline axial-vector current and show in detail how the chiral anomaly appears. Our work provides a systematic framework for a relativistic kinetic theory of chiral fermions in the fluctuating topological backgrounds that generate the CME in a deconfined quark-gluon plasma. We outline some further applications of this framework in many-body systems.
The azimuthal collimation of dihadrons with large rapidity separations in high multiplicity p+p collisions at the LHC is described in the color glass condensate (CGC) effective theory A. Dumitru, K. ...Dusling, F. Gelis, J. Jalilian-Marian, T. Lappi, and R. Venugopalan, Phys. Lett. B 697, 21 (2011). by N(c)(2) suppressed multiladder QCD diagrams that are enhanced α(S)(-8) due to gluon saturation in hadron wave functions. We show that quantitative computations in the CGC framework are in good agreement with data from the CMS experiment on per trigger dihadron yields and predict further systematics of these yields with varying trigger p(T) and charged hadron multiplicity. Radial flow generated by rescattering is strongly limited by the structure of the p+p dihadron correlations. In contrast, radial flow explains the systematics of identical measurements in heavy ion collisions.
We compute initial conditions in heavy ion collisions within the color glass condensate framework by combining the impact parameter dependent saturation model with the classical Yang-Mills ...description of initial Glasma fields. In addition to fluctuations of nucleon positions, this impact parameter dependent Glasma description includes quantum fluctuations of color charges on the length scale determined by the inverse nuclear saturation scale Q(s). The model naturally produces initial energy fluctuations that are described by a negative binomial distribution. The ratio of triangularity to eccentricity ε(3)/ε(2) is close to that in a model tuned to reproduce experimental flow data. We compare transverse momentum spectra and v(2,3,4)(p(T)) of pions from different models of initial conditions using relativistic viscous hydrodynamic evolution.
We show that gluon saturation gives rise to a strong modification of the scaling in both the nuclear mass number A and the virtuality Q2 of the vector meson production cross-section in exclusive ...deep-inelastic scattering off nuclei. We present qualitative analytic expressions for how the scaling exponents are modified as well as quantitative predictions that can be tested at an Electron–Ion Collider.
Qualitative features of multiparticle correlations in light-heavy ion (p+A) collisions at RHIC and LHC are reproduced in a simple initial state model of partons in the projectile coherently ...scattering off localized domains of color charge in the heavy nuclear target. These include (i) the ordering of the magnitudes of the azimuthal angle nth Fourier harmonics of two-particle correlations v_{n}{2}, (ii) the energy and transverse momentum dependence of the four-particle Fourier harmonic v_{2}{4}, and (iii) the energy dependence of four-particle symmetric cumulants measuring correlations between different Fourier harmonics. Similar patterns are seen in an Abelian version of the model, where we observe v_{2}{2}>v_{2}{4}≈v_{2}{6}≈v_{2}{8} of two, four, six, and eight particle correlations. While such patterns are often interpreted as signatures of collectivity arising from hydrodynamic flow, our results provide an alternative description of the multiparticle correlations seen in p+A collisions.
We outline a strategy to compute deeply inelastic scattering structure functions using a hybrid quantum computer. Our approach takes advantage of the representation of the fermion determinant in the ...QCD path integral as a quantum mechanical path integral over 0 + 1 -dimensional fermionic and bosonic worldlines. The proper time evolution of these worldlines can be determined on a quantum computer. While extremely challenging in general, the problem simplifies in the Regge limit of QCD, where the interaction of the worldlines with gauge fields is strongly localized in proper time and the corresponding quantum circuits can be written down. As a first application, we employ the color glass condensate effective theory to construct the quantum algorithm for a simple dipole model of the F2 structure function. We outline further how this computation scales up in complexity and extends in scope to other real-time correlation functions.
In a previous paper (arXiv:1011.1895), we showed that saturation models, constrained by e+p HERA data on inclusive and diffractive cross-sections, are in good agreement with p+p data at LHC in the ...soft sector. Particularly impressive was the agreement of saturation models with the multiplicity distribution as a function of nch.. In this Letter, we extend these studies further and consider the agreement of these models with data on bulk distributions in A+A collisions. We compare our results to data on central and forward particle production in d+Au collisions at RHIC and make predictions for inclusive distributions in p+Pb collisions at the LHC.
In 1, we showed that the gravitational wave spectrum from trans-Planckian shockwave scattering in Einstein gravity is determined by the gravitational Lipatov vertex expressed as the bilinear double ...copy Γμν=12CμCν−12NμNν where Cμ is the QCD Lipatov vertex and Nμ is the QED soft photon factor. We show here that this result can be directly obtained by careful application of the classical color-kinematic duality to the spectrum obtained in gluon shockwave collisions.
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