We have analyzed identified particle transverse momentum spectra in high multiplicity events in pp collisions at LHC energies s=0.9–13 TeV published by the CMS Collaboration using the color string ...percolation model (CSPM). In CSPM color strings are formed after the collision, which decay into new strings through color neutral q−q¯ pairs production. With the increase in the pp collisions energy number of strings grow and randomly statistically overlap producing higher string tension of the composite strings. The net color in the overlap string area is a vector sum of the randomly oriented strings. The Schwinger color string breaking mechanism produces these color neutral q−q¯ pairs at time ∼1 fm/c, which subsequently hadronize. The initial temperature is extracted both in low and high multiplicity events.The shear viscosity to entropy density ratios η/s are obtained as a function of temperature. For the higher multiplicity events at s=7 and 13 TeV the initial temperature is above the universal hadronization temperature and is consistent with the creation of deconfined matter. The η/s is similar to that in Au+Au collisions at sNN=200 GeV. The small value of η/s above the universal hadronization temperature suggested that the matter is a strongly coupled quark gluon plasma. In these small systems it can be argued that the thermalization is a consequence of the quantum tunneling through the event horizon introduced by the quarks confined in the colliding nucleons and their deceleration due to string formation, in analogy to the Hawking-Unruh radiation which provides a stochastic approach to equilibrium. The disk areas cluster on the nucleon transverse collision area. At the 2D percolation threshold a macroscopic spanning cluster suddenly occurs at the temperature Ti=Th, representing a small connected droplet of q−q¯ pairs, the quark-gluon plasma (QGP). Th is the universal hadronization temperature ∼167.7 MeV. The collision energy dependent buildup of the 2D percolation clusters defines the temperature range 159±9 MeV of the crossover transition between hadrons to the QGP in reasonable agreement with the lattice quantum chromodynamics (LQCD) pseudocritical temperature value of 155±9 MeV. Color string percolation model is the new initial stage paradigm for the study of the high density matter produced in pp and A+A collisions. With CSPM we can directly explore the thermodynamics of the QGP above the universal hadronization temperature.
We present the extraction of the temperature by analyzing the charged particle transverse momentum spectra in lead–lead (Pb–Pb) and proton–proton (
pp
) collisions at LHC energies from the ALICE ...Collaboration using the Color String Percolation Model (CSPM). From the measured energy density
ε
and the temperature T the dimensionless quantity
ε
/
T
4
is obtained to get the degrees of freedom (DOF),
ε
/
T
4
=
DOF
π
2
/
30
. We observe for the first time a two-step behavior in the increase of DOF, characteristic of deconfinement, above the hadronization temperature at temperature
∼
210 MeV for both Pb–Pb and
pp
collisions and a sudden increase to the ideal gas value of
∼
47
corresponding to three quark flavors in the case of Pb–Pb collisions.
Human lung tissue-resident NK cells (trNK cells) are likely to play an important role in host responses towards viral infections, inflammatory conditions and cancer. However, detailed insights into ...these cells are still largely lacking. Here we show, using RNA sequencing and flow cytometry-based analyses, that subsets of human lung CD69
CD16
NK cells display hallmarks of tissue-residency, including high expression of CD49a, CD103, and ZNF683, and reduced expression of SELL, S1PR5, and KLF2/3. CD49a
CD16
NK cells are functionally competent, and produce IFN-γ, TNF, MIP-1β, and GM-CSF. After stimulation with IL-15, they upregulate perforin, granzyme B, and Ki67 to a similar degree as CD49a
CD16
NK cells. Comparing datasets from trNK cells in human lung and bone marrow with tissue-resident memory CD8
T cells identifies core genes co-regulated either by tissue-residency, cell-type or location. Together, our data indicate that human lung trNK cells have distinct features, likely regulating their function in barrier immunity.
We present our results on the shear viscosity to entropy ratio (
η
/
s
) in the framework of the clustering of the color sources of the matter produced at RHIC and LHC energies. The onset of ...de-confinement transition is identified by the spanning percolating cluster in 2D percolation. The relativistic kinetic theory relation for
η
/
s
is evaluated using the initial temperature (
T
) and the mean free path (
λ
mfp
). The analytic expression for
η
/
s
covers a wide temperature range. At
T
∼150 MeV below the hadron to QGP transition temperature of ∼168 MeV, with increasing temperatures the
η
/
s
value drop sharply and reaches a broad minimum
η
/
s
∼0.20 at
T
∼175–185 MeV. Above this temperature
η
/
s
grows slowly. The measured values of
η
/
s
are 0.204±0.020 and 0.262±0.026 at the initial temperature of 193.6±3 MeV from central Au+Au collisions at
(RHIC) and 262.2±13 MeV in central Pb+Pb collisions at
(LHC). These
η
/
s
values are 2.5 and 3.3 times the AdS/CFT conjectured lower bound 1/4
π
but are consistent with theoretical
η
/
s
estimates for a strongly coupled QGP.
In the present work we have analyzed the transverse momentum spectra of charged particles in high multiplicity pp collisions at LHC energies s=5.02 and 13 TeV published by the ALICE Collaboration ...using the Color String Percolation Model. For heavy ions Pb-Pb at sNN=2.76 and 5.02 TeV along with Xe-Xe at sNN=5.44 TeV have been analyzed. The initial temperature is extracted both in low and high multiplicity events in pp collisions. For A−A collisions the temperature is obtained as a function of centrality. A universal scaling in the temperature from pp and A−A collisions is obtained when multiplicity is scaled by the transverse interaction area. From the measured energy density ε and the temperature the dimensionless quantity ε/T4 is obtained. Our results for Pb-Pb and Xe-Xe collisions show a sharp increase in ε/T4 above T ∼ 210 MeV and reaching the ideal gas of quarks and gluons value of ε/T4∼16 at temperature ∼230 MeV.
Parity (P)-odd domains, corresponding to nontrivial topological solutions of the QCD vacuum, might be created during relativistic heavy-ion collisions. These domains are predicted to lead to charge ...separation of quarks along the orbital momentum of the system created in noncentral collisions. To study this effect, we investigate a three-particle mixed-harmonics azimuthal correlator which is a P-even observable, but directly sensitive to the charge-separation effect. We report measurements of this observable using the STAR detector in Au+Au and Cu+Cu collisions at {radical}s{sub NN} = 200 and 62 GeV. The results are presented as a function of collision centrality, particle separation in rapidity, and particle transverse momentum. A signal consistent with several of the theoretical expectations is detected in all four data sets. We compare our results to the predictions of existing event generators and discuss in detail possible contributions from other effects that are not related to P violation.
A brief introduction of the relationship of string percolation to the Quantum Chromo Dynamics (QCD) phase diagram is presented. The behavior of the Polyakov loop close to the critical temperature is ...studied in terms of the color fields inside the clusters of overlapping strings, which are produced in high energy hadronic collisions. The non-Abelian nature of the color fields implies an enhancement of the transverse momentum and a suppression of the multiplicities relative to the non overlapping case. The prediction of this framework is compared with experimental results from the SPS, RHIC and LHC for pp and AA collisions. Rapidity distributions, probability distributions of transverse momentum and multiplicities, Bose–Einstein correlations, elliptic flow and ridge structures are used to evaluate these comparison.
The thermodynamical quantities, the temperature, and energy density derived from RHIC and LHC data and Color String Percolation Model (CSPM) are used to obtain the shear viscosity to entropy density ratio (η/s). It was observed that the inverse of (η/s) represents the trace anomaly Δ=(ε−3P)/T4. Thus the percolation approach within CSPM can be successfully used to describe the initial stages in high energy heavy ion collisions in the soft region in high energy heavy ion collisions. The thermodynamical quantities, temperature and the equation of state are in agreement with the lattice QCD calculations. Thus the clustering of color sources has a clear physical basis although it cannot be deduced directly from QCD.
We present the measurement of the transverse single-spin asymmetry of weak boson production in transversely polarized proton-proton collisions at s=500 GeV by the STAR experiment at RHIC. The ...measured observable is sensitive to the Sivers function, one of the transverse-momentum-dependent parton distribution functions, which is predicted to have the opposite sign in proton-proton collisions from that observed in deep inelastic lepton-proton scattering. These data provide the first experimental investigation of the nonuniversality of the Sivers function, fundamental to our understanding of QCD.
In this study, we present results of analyses of two-pion interferometry in Au+Au collisions at √sNN = 7.7, 11.5, 19.6, 27, 39, 62.4, and 200 GeV measured in the STAR detector as part of the RHIC ...Beam Energy Scan program. The extracted correlation lengths (HBT radii) are studied as a function of beam energy, azimuthal angle relative to the reaction plane, centrality, and transverse mass (mT) of the particles. The azimuthal analysis allows extraction of the eccentricity of the entire fireball at kinetic freeze-out. The energy dependence of this observable is expected to be sensitive to changes in the equation of state. A new global fit method is studied as an alternate method to directly measure the parameters in the azimuthal analysis. The eccentricity shows a monotonic decrease with beam energy that is qualitatively consistent with the trend from all model predictions and quantitatively consistent with a hadronic transport model.
The initial temperature Ti, energy density ϵi, and formation time τi of the initial state of the QGP formed in the heavy ion collisions at RHIC and LHC energies are determined using the data driven ...Color String Percolation Model (CSPM). Multiparticle production by interacting strings stretched between projectile and target form a spanning cluster at the percolation threshold. The relativistic kinetic theory relation for η/s is evaluated as a function of T and the mean free path (λmfp) using data and CSPM. η/s(Ti, λmfp) describes the transition from a strongly interacting QGP at T/Tc ~ 1 to a weakly coupled QGP at T/Tc ≥ 6. We find that the reciprocal of η/s is equal to the trace anomaly Δ ϵ − 3P/T4 which also describes the transition. We couple this initial state of the QGP to a ID Bjorken expansion to determine the sound velocity c2s of the QGP for 0.85 ≤ T/Tc ≤ 3. The bulk thermodynamic quantities and the equation of state are in excellent agreement with LQCD results.
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