scholarly journals QCD at finite isospin chemical potential

2018 ◽  
Vol 175 ◽  
pp. 07020 ◽  
Author(s):  
Bastian B. Brandt ◽  
Gergely Endrődi ◽  
Sebastian Schmalzbauer
Keyword(s):  
Taylor Expansion ◽  
Chemical Potential ◽  
Quark Masses ◽  
Monte Carlo Techniques ◽  
Chemical Potentials ◽  
Cosmological Application ◽  
Sign Problem ◽  
Charged Pions ◽  
First Results

We investigate the properties of QCD at finite isospin chemical potential at zero and non-zero temperatures. This theory is not affected by the sign problem and can be simulated using Monte-Carlo techniques. With increasing isospin chemical potential and temperatures below the deconfinement transition the system changes into a phase where charged pions condense, accompanied by an accumulation of low modes of the Dirac operator. The simulations are enabled by the introduction of a pionic source into the action, acting as an infrared regulator for the theory, and physical results are obtained by removing the regulator via an extrapolation. We present an update of our study concerning the associated phase diagram using 2+1 flavours of staggered fermions with physical quark masses and the comparison to Taylor expansion. We also present first results for our determination of the equation of state at finite isospin chemical potential and give an example for a cosmological application. The results can also be used to gain information about QCD at small baryon chemical potentials using reweighting with respect to the pionic source parameter and the chemical potential and we present first steps in this direction.

scholarly journals Lattice QCD at Finite Temperature and Density

2007 ◽  
Vol 22 (07n10) ◽  
pp. 457-471 ◽  
Author(s):  
M. P. LOMBARDO
Keyword(s):  
Lattice Qcd ◽  
Finite Temperature ◽  
Taylor Expansion ◽  
Critical Line ◽  
Chemical Potential ◽  
Normal Phase ◽  
Theoretical Physics ◽  
General Introduction ◽  
Sign Problem ◽  
The Subject

A general introduction into the subject aimed at a general theoretical physics audience. We introduce the sign problem posed by finite density lattice QCD, and we discuss the main methods proposed to circumvent it, with emphasis on the imaginary chemical potential approach. The interrelation between Taylor expansion and analytic continuation from imaginary chemical potential is discussed in detail. The main applications to the calculation of the critical line, and to the thermodynamics of the hot and normal phase are reviewed.

scholarly journals PHASE DIAGRAM OF THE STRONG INTERACTION SYSTEM FROM LATTICE QCD

2011 ◽  
Vol 01 ◽  
pp. 28-33
Author(s):  
SEYONG KIM
Keyword(s):  
Phase Diagram ◽  
Thermodynamic Properties ◽  
Lattice Qcd ◽  
Strong Interaction ◽  
Accurate Determination ◽  
Baryon Density ◽  
Quark Masses ◽  
Interaction System ◽  
Sign Problem

We briefly review recent progresses in studying QCD thermodynamics from lattice QCD. Investigation of QCD in zero baryon density shows a rapid cross-over with realistic (u, d, s) quark masses. Various improvements of lattice QCD action leads to more accurate determination of QCD thermodynamic properties. Although simulating QCD in non-zero baryon density is difficult due to "sign problem", steady progress is also achieved.

scholarly journals Strangeness production in high-energy collisions and Hawking–Unruh radiation

2017 ◽  
Vol 26 (03) ◽  
pp. 1750001 ◽  
Author(s):  
Abdel Nasser Tawfik ◽  
Hayam Yassin ◽  
Eman R. Abo Elyazeed
Keyword(s):  
Black Hole ◽  
Particle Production ◽  
Chemical Potential ◽  
Average Energy ◽  
High Energy ◽  
Strangeness Production ◽  
Linear Sigma Model ◽  
Quark Masses ◽  
Chemical Potentials ◽  
Particle Ratios

The assumption that the production of quark–antiquark pairs and their sequential string-breaking takes place, likely as a tunneling process, through the event horizon of the color confinement determines the freezeout temperature and gives a plausible interpretation for the thermal pattern of elementary and nucleus–nucleus collisions. When relating the black-hole electric charges to the baryon-chemical potentials, it was found that the phenomenologically deduced parameters from the ratios of various particle species and the higher-order moments of net-proton multiplicity in the statistical thermal models and Polyakov linear-sigma model agree well with the ones determined from the thermal radiation from charged black hole. Accordingly, the resulting freezeout conditions, such as normalized entropy density [Formula: see text] and average energy per particle [Formula: see text][Formula: see text]GeV, are confirmed at finite chemical potentials as well. Furthermore, the problem of strangeness production in elementary collisions can be interpreted by thermal particle production from the Hawking–Unruh radiation. Consequently, the freezeout temperature depends on the quark masses. This leads to a deviation from full equilibrium and thus a suppression of the strangeness production in the elementary collisions. But in nucleus–nucleus collisions, an average temperature should be introduced in order to dilute the quark masses. This nearly removes the strangeness suppression. An extension to finite chemical potentials is introduced. The particle ratios of kaon-to-pion ([Formula: see text]), phi-to-kaon ([Formula: see text]) and antilambda-to-pion ([Formula: see text]) are determined from Hawking–Unruh radiation and compared with the thermal calculations and the measurements in different experiments. We conclude that these particle ratios can be reproduced, at least qualitatively, as Hawking–Unruh radiation at finite chemical potential. With increasing energy, both [Formula: see text] and [Formula: see text] keep their maximum values at low SPS energies. But the further energy decrease rapidly reduces both ratios. For [Formula: see text], there is an increase with increasing [Formula: see text], i.e., no saturation is to be observed.

scholarly journals Lattice Constraints on the QCD Chiral Phase Transition at Finite Temperature and Baryon Density

Symmetry ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 2079
Author(s):  
Owe Philipsen
Keyword(s):  
Phase Transition ◽  
Chemical Potential ◽  
Baryon Density ◽  
Variable Number ◽  
Current Data ◽  
Crossover Region ◽  
Chiral Phase ◽  
Quark Masses ◽  
Sign Problem ◽  
Genuine Solution

The thermal restoration of chiral symmetry in QCD is known to proceed by an analytic crossover, which is widely expected to turn into a phase transition with a critical endpoint as the baryon density is increased. In the absence of a genuine solution to the sign problem of lattice QCD, simulations at zero and imaginary baryon chemical potential in a parameter space enlarged by a variable number of quark flavours and quark masses constitute a viable way to constrain the location of a possible non-analytic phase transition and its critical endpoint. In this article I review recent progress towards an understanding of the nature of the transition in the massless limit, and its critical temperature at zero density. Combined with increasingly detailed studies of the physical crossover region, current data bound a possible critical point to μB ≳ 3T.

Determination of Substitutional-Interstitial Interaction from Chemical Potentials of Interstitials in the Steel Matrix

2014 ◽  
Vol 922 ◽  
pp. 645-650
Author(s):  
Yao V. Shan ◽  
Jiří Svoboda ◽  
Franz Dieter Fischer ◽  
E. Kozeschnik
Keyword(s):  
Chemical Potential ◽  
Steel Matrix ◽  
Carbon And Nitrogen ◽  
Chemical Potentials ◽  
Substitutional Solute ◽  
Different Depths ◽  
Solute Atoms ◽  
The One ◽  
Trapping Sites

The interaction between interstitially diffusing atoms and substitutional solute atoms, acting as trapping sites, causes a non-negligible influence on the diffusion process itself and, consequently, on many aspects of alloys, such as phase transformations, solubility, precipitation of carbides and nitrides etc. The most important quantity in this treatment is the so-called trapping enthalpy (depth of trap), which has been used in several approaches in literature over the last century. However, the determination of the trapping enthalpy so far relies on approximations or assumptions on the one hand (statistical approaches, quasi chemical approach) or is significantly limited due to high complexity (ab initio approaches) on the other hand. The model introduced in this paper illustrates a rigorous and efficient thermodynamically-based concept utilizing only the dependence of the chemical potential of the interstitial component on the chemical composition of the alloy. Such a dependency is available in a very precise form from CALPHAD thermodynamic databases. Using the most recent databases available, the trapping enthalpies of carbon and nitrogen at various solute atoms (trapping sites) are evaluated for austenitic and ferritic steels. Good agreement with previous literature results is observed. The flexibility of the concept allows also for the treatment of trapping in a multi-component system, where different types of solute atoms are responsible for different depths of traps.

scholarly journals Isospin asymmetry in holographic baryonic matter

2021 ◽  
Vol 11 (2) ◽  
Author(s):  
Nicolas Kovensky ◽  
Andreas Schmitt
Keyword(s):  
Chemical Potential ◽  
Chiral Limit ◽  
Compact Stars ◽  
Gauge Fields ◽  
Baryonic Matter ◽  
Isospin Asymmetry ◽  
Pion Condensation ◽  
Chemical Potentials ◽  
First Results ◽  
Realistic Description

We study baryonic matter with isospin asymmetry, including fully dynamically its interplay with pion condensation. To this end, we employ the holographic Witten-Sakai-Sugimoto model and the so-called homogeneous ansatz for the gauge fields in the bulk to describe baryonic matter. Within the confined geometry and restricting ourselves to the chiral limit, we map out the phase structure in the presence of baryon and isospin chemical potentials, showing that for sufficiently large chemical potentials condensed pions and isospin-asymmetric baryonic matter coexist. We also present first results of the same approach in the deconfined geometry and demonstrate that this case, albeit technically more involved, is better suited for comparisons with and predictions for real-world QCD. Our study lays the ground for future improved holographic studies aiming towards a realistic description of charge neutral, beta-equilibrated matter in compact stars, and also for more refined comparisons with lattice studies at nonzero isospin chemical potential.

Determination of the Recent Tectonic Movements Using GPS and Insar Methods; The First Results From the Eastern Part of the Gediz Graben

2015 ◽  
Author(s):  
Fatih POYRAZ ◽  
Orhan TATAR ◽  
Kemal Özgür HASTAOĞLU ◽  
İbrahim TİRYAKİOĞLU ◽  
Önder GÜRSOY ◽  
...  
Keyword(s):  
First Results ◽  
Tectonic Movements

scholarly journals More on complex Sachdev-Ye-Kitaev eternal wormholes

2021 ◽  
Vol 2021 (3) ◽  
Author(s):  
Pengfei Zhang
Keyword(s):  
Black Hole ◽  
Ground State ◽  
Effective Action ◽  
Chemical Potential ◽  
Specific Charge ◽  
Zero Temperature ◽  
Small Coupling ◽  
Chemical Potentials ◽  
Quench Dynamics ◽  
Two Sides

Abstract In this work, we study a generalization of the coupled Sachdev-Ye-Kitaev (SYK) model with U(1) charge conservations. The model contains two copies of the complex SYK model at different chemical potentials, coupled by a direct hopping term. In the zero-temperature and small coupling limit with small averaged chemical potential, the ground state is an eternal wormhole connecting two sides, with a specific charge Q = 0, which is equivalent to a thermofield double state. We derive the conformal Green’s functions and determine corresponding IR parameters. At higher chemical potential, the system transit into the black hole phase. We further derive the Schwarzian effective action and study its quench dynamics. Finally, we compare numerical results with the analytical predictions.

scholarly journals Smart optical cross dipole nanoantenna with multibeam pattern

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Seyyed Mohammad Mehdi Moshiri ◽  
Najmeh Nozhat
Keyword(s):  
Radiation Pattern ◽  
Chemical Potential ◽  
Monolayer Graphene ◽  
Absorption Characteristic ◽  
Radiation Beam ◽  
Directional Radiation ◽  
Chemical Potentials ◽  
Different Types ◽  
Absorption Power ◽  
Maximum Directivity

AbstractIn this paper, an optical smart multibeam cross dipole nano-antenna has been proposed by combining the absorption characteristic of graphene and applying different arrangements of directors. By introducing a cross dipole nano-antenna with two V-shaped coupled elements, the maximum directivity of 8.79 dBi has been obtained for unidirectional radiation pattern. Also, by applying various arrangements of circular sectors as director, different types of radiation pattern such as bi- and quad-directional have been attained with directivities of 8.63 and 8.42 dBi, respectively, at the wavelength of 1550 nm. The maximum absorption power of graphene can be tuned by choosing an appropriate chemical potential. Therefore, the radiation beam of the proposed multibeam cross dipole nano-antenna has been controlled dynamically by applying a monolayer graphene. By choosing a suitable chemical potential of graphene for each arm of the suggested cross dipole nano-antenna without the director, the unidirectional radiation pattern shifts ± 13° at the wavelength of 1550 nm. Also, for the multibeam nano-antenna with different arrangements of directors, the bi- and quad-directional radiation patterns have been smartly modified to uni- and bi-directional ones with the directivities of 10.1 and 9.54 dBi, respectively. It is because of the graphene performance as an absorptive or transparent element for different chemical potentials. This feature helps us to create a multipath wireless link with the capability to control the accessibility of each receiver.

scholarly journals Probing Dense QCD Matter: Muon Measurements with the CBM Experiment at FAIR

Particles ◽  
2021 ◽  
Vol 4 (2) ◽  
pp. 205-213
Author(s):  
Anna Senger ◽  
Peter Senger
Keyword(s):  
Performance Studies ◽  
Reaction Rates ◽  
High Density ◽  
Streaming Data ◽  
Qcd Phase Diagram ◽  
Chemical Potentials ◽  
Muon Pairs ◽  
Caloric Curve ◽  
Density Equation

The Compressed Baryonic Matter (CBM) experiment at the future Facility for Antiproton and Ion Research (FAIR) in Darmstadt is designed to investigate the properties of high-density QCD matter with multi-differential measurements of hadrons and leptons, including rare probes such as multi-strange anti-hyperons and charmed particles. The research program covers the study of the high-density equation-of-state of nuclear matter and the exploration of the QCD phase diagram at large baryon chemical potentials, including the search for quark matter and the critical endpoint of a hypothetical 1st order phase transition. The CBM setup comprises detector systems for the identification of charged hadrons, electrons, and muons; for the determination of collision centrality and the orientation of the reaction plane; and a free-streaming data read-out and acquisition system, which allows online reconstruction and selection of events up to reaction rates of 10 MHz. In this article, emphasis is placed on the measurement of muon pairs in Au-Au collisions at FAIR beam energies, which are unique probes used to determine the temperature of the fireball, and hence to search for a caloric curve of QCD matter. Simultaneously, the subthreshold production of charmonium can be studied via its dimuon decay in order to shed light on the microscopic structure of QCD matter at high baryon densities. The CBM setup with focus on dimuon measurements and the results of the corresponding physics performance studies will be presented.

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