scholarly journals Momentum Space Topology and Non-Dissipative Currents †

Universe ◽  
2018 ◽  
Vol 4 (12) ◽  
pp. 146 ◽  
Author(s):  
Mikhail Zubkov ◽  
Zakhar Khaidukov ◽  
Ruslan Abramchuk

Relativistic heavy ion collisions represent an arena for the probe of various anomalous transport effects. Those effects, in turn, reveal the correspondence between the solid state physics and the high energy physics, which share the common formalism of quantum field theory. It may be shown that for the wide range of field–theoretic models, the response of various nondissipative currents to the external gauge fields is determined by the momentum space topological invariants. Thus, the anomalous transport appears to be related to the investigation of momentum space topology—the approach developed earlier mainly in the condensed matter theory. Within this methodology we analyse systematically the anomalous transport phenomena, which include, in particular, the anomalous quantum Hall effect, the chiral separation effect, the chiral magnetic effect, the chiral vortical effect and the rotational Hall effect.

2018 ◽  
Vol 191 ◽  
pp. 05007 ◽  
Author(s):  
Mikhail Zubkov ◽  
Zakhar Khaidukov

Using the derivative expansion applied to the Wigner transform of the two - point Green function this is possible to derive the response of various nondissipative currents to the external gauge fields. The corresponding currents are proportional to the momentum space topological invariants. This allows to analyse systematically various anomalous transport phenomena including the anomalous quantum Hall effect and the chiral separation effect. We discuss the application of this methodology both to the solid state physics and to the high energy physics.


2002 ◽  
Vol 17 (30) ◽  
pp. 4615-4634 ◽  
Author(s):  
BHASKAR DE ◽  
S. BHATTACHARYYA ◽  
P. GUPTAROY

The present paper aims at testing a very simple approach to interpret the characteristics of inclusive production of pions in high energy NA and AA collisions by a somewhat in-depth analysis of the same for NN interactions; and also at reporting here thus some interesting observations made on the nature of rapidity and transverse momentum spectra of the produced pions. And this approach is built upon a newly offered master formula holding the key for converting the results of high energy nucleon–nucleon (NN) collision to the corresponding observables on differential and inclusive cross-sections for both nucleon–nucleus and nucleus–nucleus (heavy ion) collisions in a generalized form. The proposed formulae, used in a somewhat phenomenological way, can provide modestly reliable parametrization of data in the broad range of collision energy and the varied range of projectile-target combinations. This opens up the possibility of understanding in a quite unified manner the large amount of data on the rapidity and transverse momentum spectra in a wide range of interactions and energies starting right from ISR, rather Bevelac, to the relativistic heavy ion collisions (RHIC) via the various collider scales of energy. The agreements between the data and calculations, in most cases, are quite satisfactory both qualitatively and quantitatively. While highlighting this success, the limitation of the approach has also been pointed out in the end as clearly and categorically as possible.


2000 ◽  
Vol 15 (15) ◽  
pp. 2269-2288
Author(s):  
SANATAN DIGAL ◽  
RAJARSHI RAY ◽  
SUPRATIM SENGUPTA ◽  
AJIT M. SRIVASTAVA

We demonstrate the possibility of forming a single, large domain of disoriented chiral condensate (DCC) in a heavy-ion collision. In our scenario, rapid initial heating of the parton system provides a driving force for the chiral field, moving it away from the true vacuum and forcing it to go to the opposite point on the vacuum manifold. This converts the entire hot region into a single DCC domain. Subsequent rolling down of the chiral field to its true vacuum will then lead to emission of a large number of (approximately) coherent pions. The requirement of suppression of thermal fluctuations to maintain the (approximate) coherence of such a large DCC domain, favors three-dimensional expansion of the plasma over the longitudinal expansion even at very early stages of evolution. This also constrains the maximum temperature of the system to lie within a window. We roughly estimate this window to be about 200–400 MeV. These results lead us to predict that extremely high energy collisions of very small nuclei (possibly hadrons) are better suited for observing signatures of a large DCC. Another possibility is to focus on peripheral collisions of heavy nuclei.


2020 ◽  
Vol 80 (9) ◽  
Author(s):  
Shi-Yong Chen ◽  
Wei Dai ◽  
Shan-Liang Zhang ◽  
Qing Zhang ◽  
Ben-Wei Zhang

AbstractWe present the first theoretical study of medium modifications of the global geometrical pattern, i.e., transverse sphericity ($$S_{\perp }$$ S ⊥ ) distribution of jet events with parton energy loss in relativistic heavy-ion collisions. In our investigation, POWHEG + PYTHIA is employed to make an accurate description of transverse sphericity in the p + p baseline, which combines the next-to-leading order (NLO) pQCD calculations with the matched parton shower (PS). The Linear Boltzmann Transport (LBT) model of the parton energy loss is implemented to simulate the in-medium evolution of jets. We calculate the event normalized transverse sphericity distribution in central Pb + Pb collisions at the LHC, and give its medium modifications. An enhancement of transverse sphericity distribution at small $$S_{\perp }$$ S ⊥ region but a suppression at large $$S_{\perp }$$ S ⊥ region are observed in A + A collisions as compared to their p + p references, which indicates that in overall the geometry of jet events in Pb + Pb becomes more pencil-like. We demonstrate that for events with 2 jets in the final-state of heavy-ion collisions, the jet quenching makes the geometry more sphere-like with medium-induced gluon radiation. However, for events with $$\ge 3$$ ≥ 3 jets, parton energy loss in the QCD medium leads to the events more pencil-like due to jet number reduction, where less energetic jets may lose their energies and then fall off the jet selection kinematic cut. These two effects offset each other and in the end result in more jetty events in heavy-ion collisions relative to that in p + p.


Universe ◽  
2019 ◽  
Vol 5 (5) ◽  
pp. 126
Author(s):  
Andrey Seryakov

The phase diagram of the strongly interacting matter is the main research subject for different current and future experiments in high-energy physics. System size and energy scan programs aim to find a possible critical point. One of such programs was accomplished by the fixed-target NA61/SHINE experiment in 2018. It includes six beam energies and six colliding systems: p + p, Be + Be, Ar + Sc, Xe + La, Pb + Pb and p + Pb. In this study, we discuss how the efficiency of centrality selection by forward spectators influences multiplicity and fluctuation measures and how this influence depends on the size of colliding systems. We use SHIELD and EPOS Monte-Carlo (MC) generators along with the wounded nucleon model, introduce a probability to lose a forward spectator and spectator energy loss. We show that for light colliding systems such as Be or Li even a small inefficiency in centrality selection has a dramatic impact on multiplicity scaled variance. Conversely, heavy systems such as Ar + Sc are much less prone to the effect.


2007 ◽  
Vol 16 (07n08) ◽  
pp. 2381-2387
Author(s):  
G. SOOD

We propose a novel method for studying the production of anticentauro events in high energy heavy ion collisions utilizing Chebyshev expansion coefficients. These coefficients have proved to be very efficient in investigating the pattern of fluctuations in neutral pion fraction. For the anticentauro like events, the magnitude of first few coefficients is strongly enhanced (≈ 3 times) as compared to those of normal HIJING events. Various characteristics of Chebyshev coefficients are studied in detail and the probability of formation of exotic events is calculated from the simulated events.


2020 ◽  
Vol 70 (1) ◽  
pp. 293-321 ◽  
Author(s):  
Wei Li ◽  
Gang Wang

The interplay of quantum anomalies with strong magnetic fields and vorticity in chiral systems could lead to novel transport phenomena, such as the chiral magnetic effect (CME), the chiral magnetic wave (CMW), and the chiral vortical effect (CVE). In high-energy nuclear collisions, these chiral effects may survive the expansion of a quark–gluon plasma fireball and be detected in experiments. The experimental searches for the CME, the CMW, and the CVE have aroused extensive interest over the past couple of decades. The main goal of this article is to review the latest experimental progress in the search for these novel chiral transport phenomena at the Relativistic Heavy Ion Collider at Brookhaven National Laboratory and the Large Hadron Collider at CERN. Future programs to help reduce uncertainties and facilitate the interpretation of the data are also discussed.


2007 ◽  
Vol 16 (10) ◽  
pp. 3355-3362
Author(s):  
DU JIAXIN ◽  
LI NA ◽  
LIU LIANSHOU

A Monte Carlo study on the charge balance function in high energy hadron-hadron and relativistic heavy ion collisions are carried out using the Monte Carlo generators PYTHIA and AMPT, respectively. A strong dependence of the width of balance function on multiplicity is found in both cases. Using the mean parton-freeze-out time of a heavy-ion-collision event as the characteristic hadronization time for the event, it is found that for a fixed multiplicity interval the width of balance function is consistent with being independent of hadronization time.


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