Nuclear Theory·nucl-th

Monday·December 4, 2017

7 papers—3 primary·4 cross-listed

01
Scattering using real-time path integrals
W. N. Polyzou🇺🇸 · Ekaterina Nathanson🇺🇸
Background: Path integrals are a powerful tool for solving problems in quantum theory that are not amenable to a treatment by perturbation theory. Most path integral computations require an analytic continuation to imaginary time. While imaginary time treatments of scattering are possible, imaginary time is not a natural framework for treating scattering problems. Purpose: To test a recently introduced method for performing direct calculations of scattering observables using real-time path integrals. Methods: The computations are based on a new interpretation of the path integral as the expectation value of a potential functional on a space of continuous paths with respect to a complex probability distribution. The method has the advantage that it can be applied to arbitrary short-range potentials. Results: The new method is tested by applying it to calculate half-shell sharp-momentum transition matrix elements for one-dimensional potential scattering. The calculations for half shell transition operator matrix elements are in agreement with a numerical solution of the Lippmann-Schwinger equation. The computational method has a straightforward generalization to more complicated systems.
nucl-thhep-lathep-thPRC(2020)·4 citations
02
An Initial State with Shear in Peripheral Heavy Ion Collisions
V.K. Magas🇪🇸 · J. Gordillo🇪🇸 · D. Strottman🇳🇴 · Y.L. Xie🇳🇴 · L.P. Csernai🇳🇴
In the present work we propose a new initial state model for hydrodynamic simulation of relativistic heavy ion collisions based on Bjorken-like solution applied streak by streak in the transverse plane. Previous fluid dynamical calculations in Cartesian coordinates with an initial state based on a streak by streak Yang-Mills field led for peripheral higher energy collisions to large angular momentum, initial shear flow and significant local vorticity. Recent experiments verified the existence of this vorticity via the resulting polarization of emitted $Λ$ and $Λ ˉ$ particles. At the same time parton cascade models indicated the existence of more compact initial state configurations, which we are going to simulate in our approach. The proposed model satisfies all the conservation laws including conservation of a strong initial angular momentum which is present in non-central collisions. As a consequence of this large initial angular momentum we observe the rotation of the whole system as well as the fluid shear in the initial state, which leads to large flow vorticity. Another advantage of the proposed model is that the initial state can be given in both [t,x,y,z] and $[τ, x, y, η]$ coordinates, and thus can be tested by all 3+1D hydrodynamical codes which exist in the field.
nucl-thPRC(2018)·4 citations
03
Possibility of shears mechanism due to attractive interaction in the island of $A$ $\sim$ 140 region
S. Rajbanshi
The present work identify an island in the values of dimensionless parameter $χ$ as +0.10 $<$ $χ$ $<$ +0.55 outside which no magnetic rotational (MR) bands due to the repulsive interaction would be observed. The semi-classical calculations within the hybrid shears mechanism with the principal axis cranking model (HSPAC) reveal the possibility of the shears band due to the attractive interaction for nuclei in A $\sim$ 140 region. Though the limited information exists in literature, the HSPAC calculation exhibits the dipole bands above the 4389-keV and 4160-keV excited states in $^{145}$ Sm and $^{146}$ Eu nuclei, respectively, demand their candidature of the attractive shears bands. Other interesting consequence of the HSPAC calculations is the increasing nature of the $B (M 1)$ and $B (E 2)$ transition strengths with spin unlike the decreasing nature of the transition strengths ( $B (M 1)$ and $B (E 2)$ values) of the MR bands. Thus measurement of the transition probability has been required on urgent basis to validate the strong candidature of such an extreme excitation mechanism in $^{145}$ Sm and $^{146}$ Eu nuclei.
nucl-thnucl-ex1 citation
04
Multi-scale methods in quantum field theory
W. N.Polyzou🇺🇸 · Tracie Michlin🇺🇸 · Fatih Bulut🇹🇷
Daubechies wavelets are used to make an exact multi-scale decomposition of quantum fields. For reactions that involve a finite energy that take place in a finite volume, the number of relevant quantum mechanical degrees of freedom is finite. The wavelet decomposition has natural resolution and volume truncations that can be used to isolate the relevant degrees of freedom. The application of flow equation methods to construct effective theories that decouple coarse and fine scale degrees of freedom is examined.
↳ hep-lathep-thnucl-thFew Body Syst.(2018)·7 citations
05
Locating the critical end point using the linear sigma model coupled to quarks
A. Ayala🇿🇦 · J. A. Flores🇲🇽 · L. A. Hernandez🇲🇽 · S. Hernandez-Ortiz🇲🇽
We use the linear sigma model coupled to quarks to compute the effective potential beyond the mean field approximation, including the contribution of the ring diagrams at finite temperature and baryon density. We determine the model couplings and use them to study the phase diagram in the baryon chemical potential-temperature plane and to locate the Critical End Point.
↳ hep-phnucl-thEPJ Web Conf.(2018)·4 citations
06
$Ω_{c}$ excited states within a $SU (6)_{lsf} \times$ HQSS model
J. Nieves🇪🇸 · R. Pavao🇪🇸 · L. Tolos🇩🇪
We have reviewed the renormalization procedure used in the unitarized coupled-channel model of Phys. Rev. D85 114032 (2012), and its impact in the $C = 1$ , $S = - 2$ , and $I = 0$ sector, where five $Ω_{c}^{(*)}$ states have been recently observed by the LHCb Collaboration. The meson-baryon interactions used in the model are consistent with both chiral and heavy-quark spin symmetries and lead to a successful description of the observed lowest-lying odd parity resonances $Λ_{c} (2595)$ and $Λ_{c} (2625)$ , and $Λ_{b} (5912)$ and $Λ_{b} (5920)$ resonances. We show that some (probably at least three) of the states observed by LHCb will also have odd parity and spins $J = 1/2$ and $J = 3/2$ , belonging two of them to the same $SU (6)_{light - spin - flavor} \times$ HQSS multiplets that the latter strangenessless heavy $- Λ$ baryons.
↳ hep-phhep-exnucl-thEPJC(2018)·41 citations
07
Charmed-baryon production in antiproton-proton collisions within an effective Lagrangian model
R. Shyam🇮🇳
We study the productions of charmed baryons $Λ ˉ_{c}^{-} Λ_{c}^{+}$ , $Λ ˉ_{c}^{-} Σ_{c}^{+}$ , and $Σ ˉ^{-} Σ_{c}^{+}$ in the antiproton-proton collisions within an effective Lagrangian model that has only the baryon-meson degrees of freedom and involves the physical hadron masses. The baryon production proceeds via the $t$ -channel exchanges of $D^{0}$ and $D^{* 0}$ mesons in the initial collision of the antiproton with the target proton. The distortion effects in the initial and final states are accounted for by using an eikonal approximation-based procedure. We find that the reaction amplitudes of all the production channels are dominated by the $D^{* 0}$ meson-exchange diagrams. We discuss the relative roles of tensor and vector components of the $D^{* 0}$ coupling in the $D^{* 0}$ meson-exchange component of the total production cross sections. The magnitudes of the cross sections are predicted for each final state for the range of beam momenta of relevance to the $P ˉ A N D A$ experiment.
↳ hep-phhep-exnucl-exnucl-thPRD(2017)·6 citations

Affiliations

first authorsco-authorsvia INSPIRE

Scattering using real-time path integrals

An Initial State with Shear in Peripheral Heavy Ion Collisions

Possibility of shears mechanism due to attractive interaction in the island of A ∼ 140 region

Multi-scale methods in quantum field theory

Locating the critical end point using the linear sigma model coupled to quarks

Ωc​ excited states within a SU(6)lsf​×HQSS model

Charmed-baryon production in antiproton-proton collisions within an effective Lagrangian model

Affiliations

Possibility of shears mechanism due to attractive interaction in the island of $A$ $\sim$ 140 region

$Ω_{c}$ excited states within a $SU (6)_{lsf} \times$ HQSS model