Interacting Hadron resonance gas model within S-matrix formalism

2019 ◽  
Vol 28 (09) ◽  
pp. 1940001 ◽  
Author(s):  
Ashutosh Dash ◽  
Subhasis Samanta
Keyword(s):  
Virial Coefficients ◽  
Heavy Ion ◽  
Phase Shifts ◽  
Matrix Formalism ◽  
Ion Collisions ◽  
S Matrix ◽  
Scattering Phase ◽  
Thermodynamic Variables ◽  
K Matrix ◽  
Dynamical Information

A noninteracting hadron resonance gas model is used often to study the hadronic phase formed in heavy ion collisions. Interaction among various hadronic constituents can be included using an S-matrix-based virial expansion approach. The virial coefficients require the dynamical information about the scattering phase shifts, which is used to compute various thermodynamic observables of an interacting hadronic gas. The attractive part of the phase shifts are calculated using K-matrix formalism while the repulsive part is obtained by fitting to experimental data. Calculation of various thermodynamic variables like pressure, energy density, specific heat capacity, etc., along with the second and higher-order correlations and fluctuations of conserved charges are done, first with only attraction and then with both attraction and repulsion included. Comparison of S-matrix results indicate a better agreement with lattice QCD data than the ideal HRG model across all thermodynamic variables.

scholarly journals Unified Theory of Electrons and Photons in Heavy Ion Collisions

1980 ◽  
Vol 35 (6) ◽  
pp. 579-589 ◽  
Author(s):  
Johannes Kirsch
Keyword(s):  
Electromagnetic Field ◽  
Heavy Ion Collisions ◽  
Matrix Theory ◽  
Heavy Ion ◽  
Unified Theory ◽  
Electron Systems ◽  
New Approach ◽  
Ion Collisions ◽  
S Matrix ◽  
Molecular Radiation

We present a unified formulation of the interaction of electrons with the electromagnetic field in heavy ion collisions, based on quantized interacting fields. This reduces the effort in treating many-electron systems substantially, as compared with the usual S-matrix theory. Both formalisms are shown to be equivalent. The simplification achieved by our new approach is demonstrated in detail for the example of quasi-molecular radiation

scholarly journals Lattice phase shifts and mixing angles for an arbitrary number of coupled channels

2020 ◽  
Author(s):  
Lukas Bovermann ◽  
Evgeny Epelbaum ◽  
Hermann Krebs ◽  
Dean Lee
Keyword(s):  
Arbitrary Number ◽  
Scattering Problem ◽  
Full Rank ◽  
Phase Shifts ◽  
Lattice Method ◽  
Radial Wave ◽  
Mixing Angles ◽  
Coupled Channels ◽  
S Matrix ◽  
Scattering Phase

We present a lattice method for determining scattering phase shifts and mixing angles for the case of an arbitrary number of coupled channels. The proposed method combines a spherical wall boundary condition and a channel-mixing auxiliary potential to extract the full-rank S-matrix from the radial wave functions. We consider the scattering problem of two spin-1 bosons interacting with a test potential involving up to four coupled channels. For this benchmark system, the phase shifts and mixing angles are shown to agree on the lattice and in the continuum. Our method should allow to extend previous two-channel nuclear lattice EFT simulations to mixing of more than two partial waves.

scholarly journals COUPLED CHANNEL EFFECTS IN ππ S-WAVE INTERACTION

2005 ◽  
Vol 20 (08n09) ◽  
pp. 1905-1909 ◽  
Author(s):  
F. Q. WU ◽  
B. S. ZOU
Keyword(s):  
Wave Scattering ◽  
Wave Interaction ◽  
Matrix Formalism ◽  
S Wave ◽  
Coupled Channels ◽  
Channel Effects ◽  
Scattering Phase ◽  
Scattering Phase Shifts ◽  
Coupled Channel ◽  
K Matrix

We study coupled channel effects upon isospin I=2 and I=0 ππ S-wave interaction. With introduction of the ππ→ρρ→ππ coupled channel box diagram contribution into ππ amplitude in addition to ρ and f2(1270) exchange, we reproduce the ππ I =2 S-wave and D-wave scattering phase shifts and inelasticities up to 2 GeV quite well in a K-matrix formalism. For I=0 case, the same ππ→ρρ→ππ box diagram is found to give the largest contribution for the inelasticity among all possible coupled channels including ππ→ωω→ππ, [Formula: see text]. We also show why the broad σ appears narrower in production processes than in ππ scattering process.

scholarly journals Causality and Renormalization in Finite-Time-Path Out-of-Equilibrium ϕ3 QFT

Particles ◽  
2019 ◽  
Vol 2 (1) ◽  
pp. 92-102 ◽  
Author(s):  
Ivan Dadić ◽  
Dubravko Klabučar
Keyword(s):  
Finite Time ◽  
Matrix Theory ◽  
Heavy Ion ◽  
Potential Conflict ◽  
Composite Object ◽  
Self Energy ◽  
Time Path ◽  
Ion Collisions ◽  
S Matrix ◽  
Short Time

Our aim is to contribute to quantum field theory (QFT) formalisms useful for descriptions of short time phenomena, dominant especially in heavy ion collisions. We formulate out-of-equilibrium QFT within the finite-time-path formalism (FTP) and renormalization theory (RT). The potential conflict of FTP and RT is investigated in g ϕ 3 QFT, by using the retarded/advanced ( R / A ) basis of Green functions and dimensional renormalization (DR). For example, vertices immediately after (in time) divergent self-energy loops do not conserve energy, as integrals diverge. We “repair” them, while keeping d < 4 , to obtain energy conservation at those vertices. Already in the S-matrix theory, the renormalized, finite part of Feynman self-energy Σ F ( p 0 ) does not vanish when | p 0 | → ∞ and cannot be split to retarded and advanced parts. In the Glaser–Epstein approach, the causality is repaired in the composite object G F ( p 0 ) Σ F ( p 0 ) . In the FTP approach, after repairing the vertices, the corresponding composite objects are G R ( p 0 ) Σ R ( p 0 ) and Σ A ( p 0 ) G A ( p 0 ) . In the limit d → 4 , one obtains causal QFT. The tadpole contribution splits into diverging and finite parts. The diverging, constant component is eliminated by the renormalization condition ⟨ 0 | ϕ | 0 ⟩ = 0 of the S-matrix theory. The finite, oscillating energy-nonconserving tadpole contributions vanish in the limit t → ∞ .

scholarly journals SCATTERING PHASE SHIFTS IN QUASI-ONE-DIMENSION

2002 ◽  
Vol 16 (16) ◽  
pp. 2247-2277 ◽  
Author(s):  
P. SINGHA DEO ◽  
SWARNALI BANDOPADHYAY ◽  
SOURIN DAS
Keyword(s):  
Quantum Wires ◽  
Phase Shifts ◽  
Three Dimensions ◽  
One Dimension ◽  
Sum Rule ◽  
S Matrix ◽  
Scattering Phase ◽  
Scattering Phase Shifts ◽  
Scattering Matrix Elements ◽  
Arbitrary Energy

Scattering of an electron in quasi-one-dimensional quantum wires have many unusual features, not found in one, two or three-dimensions. In this work we analyze the scattering phase shifts due to an impurity in a multi-channel quantum wire with special emphasis on negative slopes in the scattering phase shift versus incident energy curves and the Wigner delay time. Although at first sight, the large number of scattering matrix elements show phase shifts of different character and nature, it is possible to see some pattern and understand these features. The behavior of scattering phase shifts in one-dimension can be seen as a special case of these features observed in quasi-one-dimensions. The negative slopes can occur at any arbitrary energy and Friedel sum rule is completely violated in quasi-one-dimension at any arbitrary energy and any arbitrary regime. This is in contrast to one, two or three dimensions where such negative slopes and violation of Friedel sum rule happen only at low energy where the incident electron feels the potential very strongly (i.e. there is a very well defined regime, the WKB regime, where FSR works very well). There are some novel behavior of scattering phase shifts at the critical energies where S-matrix changes dimension.

scholarly journals Thermodynamics and Fluctuations-Correlations of Conserved Charges in a Hadron Resonance Gas Model with Attractive and Repulsive Interaction within S-Matrix Formalism

Proceedings ◽  
2019 ◽  
Vol 10 (1) ◽  
pp. 25
Author(s):  
Ashutosh Dash ◽  
Bedangadas Mohanty ◽  
Subhasis Samanta
Keyword(s):  
Present Model ◽  
Entropy Density ◽  
Repulsive Interaction ◽  
Matrix Formalism ◽  
Experimental Phase ◽  
Conserved Charges ◽  
S Matrix ◽  
K Matrix ◽  
Repulsive Part ◽  
Good Agreement

We have extended the hadron resonance gas (HRG) model by including the effect of both attractive and repulsive interaction in the scattering matrix (S-matrix) formalism. The attractive part of the interaction is calculated using K-matrix formalism while the repulsive part is included by fitting to experimental phase shifts. We have calculated various thermodynamics quantities like pressure, energy density, entropy density etc. A good agreement between our calculations and the hadronic phase of the lattice QCD (LQCD) simulations is observed. We have also calculated fluctuations and correlations for various conserved charges like baryon, strangeness and electric charge. In the present model, χ B 2 , χ B S 11 and C B S agree well with the LQCD data.

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