Nuclear Theory·nucl-th

Thursday·May 7, 2015

8 papers—4 primary·4 cross-listed

01
[Submitted on 6 May 2015]
A new renormalization procedure of the quasiparticle random phase approximation
A. A. Raduta · C. M. Raduta
The ground state of a many body Hamiltonian considered in the quasiparticle representation is redefined by accounting for the quasiparticle quadrupole pairing interaction. The residual interaction of the newly defined quasiparticles is treated by the QRPA. Solutions of the resulting equations exhibit specific features. In particular, there is no interaction strength where the first root is vanishing. A comparison with other renormalization methods is presented.
Comments:
16 pages, 4 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1505.01339 [pdf]
IJMPE(2016)·2 citations
02
[Submitted on 6 May 2015]
Three-body bremsstrahlung and the rotational character of the 12C-spectrum
E. Garrido · A.S. Jensen · D.V. Fedorov
The electric quadrupole transitions between $0^{+}$ , $2^{+}$ , and $4^{+}$ states in $^{12}$ C are investigated in a $3 α$ model. The three-body wave functions are obtained by means of the hyperspherical adiabatic expansion method, and the continuum is discretized by imposing a box boundary condition. Corresponding expressions for the continuum three-body ( $3 α$ ) bremsstrahlung and photon dissociation cross sections are derived and computed for two different $α - α$ potentials. The available experimental energy dependence is reproduced and a series of other cross sections are predicted. The transition strengths are defined and derived from the cross sections, and compared to schematic rotational model predictions. The computed properties of the $^{12}$ C resonances suggest that the two lowest bands are made, respectively, by the states ${0_{1}^{+}, 2_{1}^{+}, 4_{2}^{+}}$ and ${0_{2}^{+}, 2_{2}^{+}, 4_{1}^{+}}$ . The transitions between the states in the first band are consistent with the rotational pattern corresponding to three alphas in an equal sided triangular structure. For the second band, the transitions are also consistent with a rotational pattern, but with the three alphas in an aligned distribution.
Comments:
To be published in Phys. Rev. C
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1505.01346 [pdf]
PRC(2015)·10 citations
03
[Submitted on 6 May 2015]
Three-body continuum wave functions with a box boundary condition
E. Garrido
In this work we investigate the connection between discretized three-body continuum wave functions, in particular via a box boundary condition, and the wave functions computed with the correct asymptotics. The three-body wave functions are in both cases obtained by means of the adiabatic expansion method. The information concerning all the possible incoming and outgoing channels, which appears naturally when the continuum is not discretized, seems to be lost when the discretization is implemented. In this work we show that both methods are fully equivalent, and the full information contained in the three-body wave function is actually preserved in the discrete spectrum. Therefore, in those cases when the asymptotic behaviour is not known analytically, i.e., when the Coulomb interaction is involved, the discretization technique can be safely used.
Comments:
to be published in Few-body Systems
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1505.01349 [pdf]
Few Body Syst.(2015)·5 citations
04
[Submitted on 6 May 2015]
Energy loss, hadronization and hadronic interactions of heavy flavors in relativistic heavy-ion collisions
Shanshan Cao🇺🇸 · Guang-You Qin🇨🇳 · Steffen A. Bass🇺🇸
We construct a theoretical framework to describe the evolution of heavy flavors produced in relativistic heavy-ion collisions. The in-medium energy loss of heavy quarks is described using our modified Langevin equation that incorporates both quasi-elastic scatterings and the medium-induced gluon radiation. The space-time profiles of the fireball is described by a (2+1)-dimensional hydrodynamics simulation. A hybrid model of fragmentation and coalescence is utilized for heavy quark hadronization, after which the produced heavy mesons together with the soft hadrons produced from the bulk QGP are fed into the hadron cascade UrQMD model to simulate the subsequent hadronic interactions. We find that the medium-induced gluon radiation contributes significantly to heavy quark energy loss at high $p_{T}$ ; heavy-light quark coalescence enhances heavy meson production at intermediate $p_{T}$ ; and scatterings inside the hadron gas further suppress the $D$ meson $R_{AA}$ at large $p_{T}$ and enhance its $v_{2}$ . Our calculations provide good descriptions of heavy meson suppression and elliptic flow observed at both the LHC and RHIC.
Comments:
13 pages, 12 figures
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
1505.01413 [pdf]
PRC(2015)·203 citations
05
[Submitted on 5 May 2015] (cross-list from hep-ph)
Model of the N-Quark Potential in SU(N) Gauge Theory using Gauge-String Duality
Oleg Andreev🇷🇺
We use gauge-string duality to model the $N$ -quark potential in pure Yang-Mills theories. For $S U (3)$ , the result agrees remarkably well with lattice simulations. The model smoothly interpolates between almost the $Δ$ -law at small distances and the Y-law at large distances.
Comments:
5 pages, 4 figures; v2: improved discussion, references added; v3: presentation improved
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Lattice (hep-lat); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th)
arXiv:
1505.01067 [pdf]
PLB(2016)·23 citations
06
[Submitted on 5 May 2015] (cross-list from hep-ph)
Calculating TMDs of a Large Nucleus: Quasi-Classical Approximation and Quantum Evolution
Yuri V. Kovchegov🇺🇸 · Matthew D. Sievert🇺🇸
We set up a formalism for calculating transverse-momentum-dependent parton distribution functions (TMDs) using the tools of saturation physics. By generalizing the quasi-classical Glauber-Gribov-Mueller/McLerran-Venugopalan approximation to allow for the possibility of spin-orbit coupling, we show how any TMD can be calculated in the saturation framework. This can also be applied to the TMDs of a proton by modeling it as a large "nucleus." To illustrate our technique, we calculate the quark TMDs of an unpolarized nucleus at large-x: the unpolarized quark distribution and the quark Boer-Mulders distribution. We observe that spin-orbit coupling leads to mixing between different TMDs of the nucleus and of the nucleons. We then consider the evolution of TMDs: at large-x, in the double-logarithmic approximation, we obtain the Sudakov form factor. At small-x the evolution of unpolarized-target quark TMDs is governed by BK/JIMWLK evolution, while the small-x evolution of polarized-target quark TMDs appears to be dominated by the QCD Reggeon.
Comments:
56 pages, 14 figures; v2: typos corrected, references added; v3: more typos corrected, title slightly modified
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1505.01176 [pdf]
NPB(2016)·61 citations
07
[Submitted on 5 May 2015] (cross-list from hep-ph)
Thermalization of Quark-Gluon Plasma in Magnetic Field at Strong Coupling
Kiminad A. Mamo🇺🇸 · Ho-Ung Yee🇺🇸
We study thermalization of strongly coupled gauge theory plasma in the presence of magnetic field using the AdS/CFT correspondence. We utilize the falling energy-shell model as a holographic description of gauge theory plasma undergoing thermalization, and find the effect of magnetic field on thermalization time in various space-time dimensions. Our results demonstrate that magnetic field universally hastens thermalization of strongly coupled gauge theory plasma.
Comments:
10 pages, 4 figures; references added, published in PRD
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th)
arXiv:
1505.01183 [pdf]
PRD(2015)·14 citations
08
[Submitted on 16 Apr 2015] (cross-list from hep-ph)
Excitation function of elastic $pp$ scattering from a unitarily extended Bialas-Bzdak model
F. Nemes🇨🇭 · T. Csörgő🇭🇺 · M. Csanád🇭🇺
The Bialas-Bzdak model of elastic proton-proton scattering assumes a purely imaginary forward scattering amplitude, which consequently vanishes at the diffractive minima. We extended the model to arbitrarily large real parts in a way that constraints from unitarity are satisfied. The resulting model is able to describe elastic $pp$ scattering not only at the lower ISR energies but also at $s =$ 7~TeV in a statistically acceptable manner, both in the diffractive cone and in the region of the first diffractive minimum. The total cross-section as well as the differential cross-section of elastic proton-proton scattering is predicted for the future LHC energies of $s =$ 13, 14, 15~TeV and also to 28~TeV. A non-trivial, significantly non-exponential feature of the differential cross-section of elastic proton-proton scattering is analyzed and the excitation function of the non-exponential behavior is predicted. The excitation function of the shadow profiles is discussed and related to saturation at small impact parameters.
Comments:
arXiv admin note: substantial text overlap with arXiv:1412.0813
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1505.01415 [pdf]
Int.J.Mod.Phys.A(2015)·33 citations

Affiliations

first authorsco-authorsvia INSPIRE