Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userSoft interactions in cold quark matter
149
0
0.0
(
0
)
Ask ChatGPT about the research
No Arabic abstract
Accurate knowledge of the thermodynamic properties of zero-temperature, high-density quark matter plays an integral role in attempts to constrain the behavior of the dense QCD matter found inside neutron-star cores, irrespective of the phase realized inside the stars. In this Letter, we consider the weak-coupling expansion of the dense QCD equation of state and compute the next-to-next-to-next-to-leading-order contribution arising from the non-Abelian interactions among long-wavelength, dynamically screened gluonic fields. Accounting for these interactions requires an all-loop resummation, which can be performed using hard-thermal-loop (HTL) kinematic approximations. Concretely, we perform a full two-loop computation using the HTL effective theory, valid for the long-wavelegth, or soft, modes. We find that the soft sector is well-behaved within cold quark matter, contrary to the case encountered at high temperatures, and find that the new contribution decreases the renormalization-scale dependence of the equation of state at high density.
rate research
Read More
High-order perturbative calculations for thermodynamic quantities in QCD are complicated by the physics of dynamical screening that affects the soft, long-wavelength modes of the system. Here, we provide details for the evaluation of this soft contribution to the next-to-next-to-next-to-leading order (NNNLO) pressure of high-density, zero-temperature quark matter (QM), complementing our accompanying paper in arXiv:2103.05658. Our calculation requires the determination of the pressure of the hard-thermal-loop (HTL) effective theory to full two-loop order at zero temperature, which we go through in considerable detail. In addition to this, we comprehensively discuss the structure of the weak-coupling expansion of the QM pressure, and lay out a roadmap towards the evaluation of the contributions missing from a full NNNLO result for this quantity.
We propose a model where the anapole appears as a hidden photon that is coupled to visible matter through a kinetic mixing. For low momentum $|{bf p}| ll M$ where $M$ is the cutoff the model (soft hidden photons limit) is reduced to the Ho-Scherrer description. We show that the hidden gauge boson is stable and therefore the hidden photons, indeed, are candidates for dark matter. Our approach shows that anapole and kinetic mixing terms are equivalent descriptions seen from different scales of energy.
By using the Nambu-Jona-Lasinio model with a tensor-type four-point interaction between quarks, it is shown that there exists a possibility of a spin polarized phase in quark matter at finite temperature and density. When there exists the spin polarization, the spontaneous magnetization may occur if the effect of the anomalous magnetic moment of quark is taken into account. An implication to the compact star objects with strong magnetic field is discussed when the spin polarization occurs.
It is shown that the spontaneous magnetization occurs due to the anomalous magnetic moments of quarks in the high-density quark matter under the tensor-type four-point interaction. The spin polarized condensate for each flavor of quark appears at high baryon density, which leads to the spontaneous magnetization due to the anomalous magnetic moments of quarks. The implications to the strong magnetic field in the compact stars is discussed.
Background: It has been proposed that the azimuthal distributions of heavy flavor quark-antiquark pairs may be modified in the medium of a heavy-ion collision. Purpose: This work tests this proposition through next-to-leading order (NLO) calculations of the azimuthal distribution, $dsigma/dphi$, including transverse momentum broadening, employing $<k_T^2>$ and fragmentation in exclusive $Q bar Q$ pair production. While these studies were done for $p+p$, $p + bar p$ and $p+$Pb collisions, understanding azimuthal angle correlations between heavy quarks in these smaller, colder systems is important for their interpretation in heavy-ion collisions. Methods: First, single inclusive $p_T$ distributions calculated with the exclusive HVQMNR code are compared to those calculated in the fixed-order next-to-leading logarithm approach. Next the azimuthal distributions are calculated and sensitivities to $<k_T^2>$, $p_T$ cut, and rapidity are studied at $sqrt{s} = 7$ TeV. Finally, calculations are compared to $Q bar Q$ data in elementary $p+p$ and $p + bar p$ collisions at $sqrt{s} = 7$ TeV and 1.96 TeV as well as to the nuclear modification factor $R_{p {rm Pb}}(p_T)$ in $p+$Pb collisions at $sqrt{s_{NN}} = 5.02$ TeV measured by ALICE. Results: The low $p_T$ ($p_T < 10$ GeV) azimuthal distributions are very sensitive to the $k_T$ broadening and rather insensitive to the fragmentation function. The NLO contributions can result in an enhancement at $phi sim 0$ absent any other effects. Agreement with the data was found to be good. Conclusions: The NLO calculations, assuming collinear factorization and introducing $k_T$ broadening, result in significant modifications of the azimuthal distribution at low $p_T$ which must be taken into account in calculations of these distributions in heavy-ion collisions.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
