Nuclear Theory
New submissions
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New submissions for Fri, 17 Nov 17
 [1] arXiv:1711.05888 [pdf, other]

Title: ProxySU(3) symmetry in heavy nuclei: Prolate dominance and prolateoblate shape transitionAuthors: S. Sarantopoulou, D. Bonatsos, I.E. Assimakis, N. Minkov, A. Martinou, R.B. Cakirli, R.F. Casten, K. BlaumComments: 10 pages, 4 tables, to appear in the proceedings of the Workshop on Shapes and Dynamics of Atomic Nuclei: Contemporary Aspects (SDANCA17, Sofia 2017), ed. N. MinkovSubjects: Nuclear Theory (nuclth)
Using a new approximate analytic parameterfree proxySU(3) scheme, simple predictions for the global feature of prolate dominance and for the locus of the prolateoblate shape transition have been made and compared with empirical data. Emphasis is placed on the mechanism leading to the breaking of the particlehole symmetry, which is instrumental in shaping up these predictions. It turns out that this mechanism is based on the SU(3) symmetry and the Pauli principle alone, without reference to any specific Hamiltonian.
 [2] arXiv:1711.05896 [pdf, ps, other]

Title: Nucleon electromagnetic form factors with nonlocal chiral effective LagrangianComments: 14 pages, 8 figuresSubjects: Nuclear Theory (nuclth)
The relativistic version of finiterangeregularisation is proposed. The covariant regulator is generated from the nonlocal Lagrangian. This nonlocal interaction is gauge invariant and is applied to study the nucleon electromagnetic form factors at momentum transfer up to 2 GeV$^2$. Both octet and decuplet intermediate states are included in the one loop calculation. Using a dipole regulator with $\Lambda$ around 0.85 GeV, the obtained form factors, electromagnetic radii as well as the ratios of the form factors are all comparable with the experimental data. This successful application of chiral effective Lagrangian to relatively large momentum transfer make it possible to further investigation of hadron quantities at high $Q^2$.
 [3] arXiv:1711.05950 [pdf, other]

Title: Comparison of heavyion transport simulations II: Collision integral in a boxAuthors: YingXun Zhang, YongJia Wang, Maria Colonna, Pawel Danielewicz, Akira Ono, Betty Tsang, Hermann Wolter, Jun Xu, LieWen Chen, Dan Cozma, ZhaoQing Feng, Subal Das Gupta, Natsumi Ikeno, CheMing Ko, BaoAn Li, QingFeng Li, ZhuXia Li, Swagata Mallik, Yasushi Nara, Tatsuhiko Ogawa, Akira Ohnishi, Dmytro Oliinychenko, Massimo Papa, Hannah Petersen, Jun Su, Taesoo Song, Janus Weil, Ning Wang, FengShou Zhang, Zhen ZhangComments: 23 pages, 10 figures. The abstract is changed a little bit due to the limits character number. The complete abstract is in the paperSubjects: Nuclear Theory (nuclth); Nuclear Experiment (nuclex)
Simulations by transport codes are indispensable to extract valuable physics information from heavy ion collisions. In order to understand the origins of discrepancies between different widely used transport codes, we compare 15 such codes under controlled conditions of a system confined to a box with periodic boundary, initialized with FermiDirac distributions at saturation density and temperatures of either 0 or 5 MeV. In such calculations, one is able to check separately the different ingredients of a transport code. In this second publication of the code evaluation project, we only consider the twobody collision term, i.e. we perform cascade calculations. When the Pauli blocking is artificially suppressed, the collision rates are found to be consistent for most codes (to within $1\%$ or better) with analytical results, or completely controlled results of a basic cascade code after eliminating the correlations within the same pair of colliding particles. In calculations with active Pauli blocking, the blocking probability was found to deviate from the expected reference values. The reason is found in substantial phasespace fluctuations and smearing tied to numerical algorithms and model assumptions in the representation of phase space. This results in the reduction of the blocking probability in most transport codes, so that the simulated system gradually evolves away from the FermiDirac towards a Boltzmann distribution. As a result of this investigation, we are able to make judgements about the most effective strategies in transport simulations for determining the collision probabilities and the Pauli blocking. Investigation in a similar vein of other ingredients in transport calculations, like the mean field propagation or the production of nucleon resonances and mesons, will be discussed in the future publications.
 [4] arXiv:1711.06008 [pdf, ps, other]

Title: A quark coalescence model for polarized vector mesons and baryonsComments: Revtex 4, 22 pages, no figureSubjects: Nuclear Theory (nuclth)
A nonrelativistic quark coalescence model is formulated for polarized vector mesons and baryons of spin1/2 octet and spin3/2 decuplet. With the spin density matrix, one can compute in a uniform way the polarizations of vector mesons and baryons from those of quarks and antiquarks with explicit momentum dependence. The results are compared to that obtained from kinetic and statistical models for hadrons.
Crosslists for Fri, 17 Nov 17
 [5] arXiv:1711.05868 (crosslist from heplat) [pdf, other]

Title: A complex path around the sign problemAuthors: Paulo F. BedaqueComments: Write up of the talk delivered al Lattice 2017Subjects: High Energy Physics  Lattice (heplat); Strongly Correlated Electrons (condmat.strel); High Energy Physics  Theory (hepth); Nuclear Theory (nuclth)
We review recent attempts at dealing with the sign problem in Monte Carlo calculations by deforming the region of integration in the path integral from real to complex fields. We discuss the theoretical foundations, the algorithmic issues and present some results for low dimensional field theories in both imaginary and real time.
 [6] arXiv:1711.06112 (crosslist from heplat) [pdf, other]

Title: $SU(2N_F)$ symmetry of confinement in QCD and its observation at high temperatureAuthors: L. Ya. GlozmanComments: 11 pages, talk presented at 6th International Conference on New Frontiers in Physics, 18.08  26.08, 2017, CreteSubjects: High Energy Physics  Lattice (heplat); High Energy Physics  Phenomenology (hepph); High Energy Physics  Theory (hepth); Nuclear Theory (nuclth)
In this talk we first overview lattice results that have led to the observation of new SU(2)_{CS} and SU(2N_F) symmetries upon artificial truncation of the nearzero modes of the Dirac operator at zero temperature and at high temperature without any truncation. These symmetries are larger than the chiral symmetry of the QCD Lagrangian and contain chiral symmetries SU(N_F)_L \times SU(N_F)_R and U(1)_A as subgroups. In addition to the standard chiral transformations the SU(2)_{CS} and SU(2N_F) transformations mix the right and lefthanded components of the quark fields. It is a symmetry of the confining chromoelectric interaction while the chromomagnetic interaction manifestly breaks it. Emergence of these symmetries upon truncation of the nearzero modes of the Dirac operator at T=0 means that all effects of the chromomagnetic interaction are located exclusively in the nearzero modes, while confining chromoelectric interaction is distributed among all modes. Appearance of these symmetries at high T, where the temperature suppresses the nearzero modes, has radical implications because these symmetries are incompatible with the asymptotically free deconfined quarks at increasing temperature. The elementary objects in the hightemperature phase of QCD should be quarks bound by the pure chromoelectric field that is not accompanied by the chromomagnetic effects.
 [7] arXiv:1711.06143 (crosslist from hepph) [pdf, other]

Title: Double heavy trihadron bound state via delocalized $π$ bondComments: 5 pages, 7 figuresSubjects: High Energy Physics  Phenomenology (hepph); Nuclear Theory (nuclth)
The number of exotic candidates which are beyond the conventional quark model has grown dramatically during the last decades. Some of them could be viewed as analogues of the deuteron. Similarly, the existence of the triton indicates that bound states formed by three hadrons could also exist. To illustrate this possibility, we study the $DD^*K$ and $BB^*\bar{K}$ systems by using the BornOppenheimer Approximation. To leading order, only onepion exchange potentials are considered, which means that the three constitutes share one virtual pion. That is similar to the role of the delocalized $\pi$ bond for the formation of Benzene in chemistry. After solving the Schr\"odinger equation, we find two threebody $DD^*K$ and $BB^*\bar{K}$ bound states with masses $4317.92_{4.32}^{+3.66}~\mathrm{MeV}$ and $11013.65_{8.84}^{+8.49}~\mathrm{MeV}$, respectively. The masses of their $D\bar{D}^*K$ and $B\bar{B}^*\bar{K}$ analogues are $4317.92_{6.55}^{+6.13}~\mathrm{MeV}$ and $11013.65_{9.02}^{+8.68}~\mathrm{MeV}$. From the experimental side, the $D\bar{D}^*K$ bound state could be found by analyzing the current world data of the $B\to J/\psi\pi\pi K$ process by focusing on the $J/\psi \pi K$ channel. Its confirmation could also help to understand the formation of kaonic nuclei in nuclear physics.
 [8] arXiv:1711.06181 (crosslist from hepph) [pdf, other]

Title: Can one ever prove that neutrinos are Dirac particles?Comments: 5 pages, 3 figuresSubjects: High Energy Physics  Phenomenology (hepph); High Energy Physics  Experiment (hepex); Nuclear Experiment (nuclex); Nuclear Theory (nuclth)
According to the "Black Box" theorem the experimental confirmation of neutrinoless double beta decay ($0 \nu 2 \beta$) would imply that at least one of the neutrinos is a Majorana particle. However, a null $0 \nu 2 \beta$ signal cannot decide the nature of neutrinos, as it can be suppressed even for Majorana neutrinos. In this letter we argue that if the null $0 \nu 2 \beta$ decay signal is accompanied by a $0 \nu 4 \beta$ quadruple beta decay signal, then at least one neutrino should be a Dirac particle. This argument holds irrespective of the underlying processes leading to such decays.
 [9] arXiv:1711.06244 (crosslist from astroph.HE) [pdf, other]

Title: Holographic compact stars meet gravitational wave constraintsAuthors: Eemeli Annala, Christian Ecker, Carlos Hoyos, Niko Jokela, David Rodríguez Fernández, Aleksi VuorinenComments: 7 pages, 5 figuresSubjects: High Energy Astrophysical Phenomena (astroph.HE); General Relativity and Quantum Cosmology (grqc); High Energy Physics  Phenomenology (hepph); Nuclear Theory (nuclth)
We investigate a simple holographic model for cold and dense deconfined QCD matter consisting of three quark flavors. Varying the single free parameter of the model and utilizing a Chiral Effective Theory equation of state (EoS) for nuclear matter, we find four different types of compact stars: traditional neutron stars, strange quark stars, and two novel solutions we refer to as hybrid stars of the second and third kind (HS2 and HS3, respectively). The HS2s are composed of a nuclear matter core and a crust made of stable strange quark matter, while the HS3s have both a quark mantle and a nuclear crust on top of a nuclear matter core. For all types of stars constructed, we determine not only their massradius relations, but also tidal deformabilities, Love numbers, as well as moments of inertia and the mass distribution. We find that there exists a range of parameter values in our model, for which the novel hybrid stars have properties in very good agreement with all existing bounds on the macroscopic properties of compact stars. In particular, the tidal deformabilities of these solutions are smaller than those of ordinary neutron stars of the same mass, implying that they provide an excellent fit to the recent gravitational wave data GW170817 of LIGO and Virgo.
 [10] arXiv:1711.06245 (crosslist from hepph) [pdf, ps, other]

Title: Effect of the chromoelectromagnetic field fluctuations on heavy quark propagation at the LHC energiesSubjects: High Energy Physics  Phenomenology (hepph); Nuclear Theory (nuclth)
We consider the effect of the chromoelectromagnetic field fluctuations in addition to the collisional as well as the radiative energy loss suffered by heavy quarks while propagating through the hot and densed deconfined medium of quarks and gluons created in relativistic heavy ion collisions. The chromoelectromagnetic field fluctuations play an important role as it leads to an energy gain of heavy quarks of all momentum, significantly effective at the lower momentum region. With this, we have computed, for the first time, the nuclear modification factor (R_{AA}) of heavy mesons, viz., Dmesons and Bmesons and compared with the those experimental measurements in PbPb collisions at \sqrt{s_{NN}} = 2.76 TeV and \sqrt{s_{NN}} = 5.02 TeV by the CMS and ALICE experiments at the LHC. Our results are found to be in very good agreement with those available data measured by CMS and ALICE experiments.
Replacements for Fri, 17 Nov 17
 [11] arXiv:1708.00177 (replaced) [pdf, ps, other]

Title: Introduction of the onebody correlation operator in the unitarymodeloperator approachComments: 16 pages, 11 figures, published in PRCSubjects: Nuclear Theory (nuclth)
 [12] arXiv:1708.00515 (replaced) [pdf, other]

Title: Bulk Viscosity of QuarkGluon Plasma in Strong Magnetic FieldsComments: 13 pages, 4 figures; v2: Eq. (2.2) corrected; v3: a paragraph added at the end of Sec. IV, also a few minor changesJournalref: Phys. Rev. D 96, 094009 (2017)Subjects: High Energy Physics  Phenomenology (hepph); Nuclear Theory (nuclth)
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