Nuclear Theory·nucl-th

Tuesday·February 14, 2017

10 papers—6 primary·4 cross-listed

01
Non-Universal and Universal Aspects of The Large Scattering Length Limit
Gerald A. Miller🇺🇸
The momentum density, $n (k)$ of interacting many-body Fermionic systems is studied (for $k > k_{F})$ using examples of several well-known two-body interaction models. This work shows that $n (k)$ can not be approximated by a zero-range model for momenta $k$ greater than about $1/ (a r_{e}^{2})^{1/3}$ , where $a$ is the scattering length, and $r_{e}$ the effective range. However, if the scattering length is large and one includes the effects of a fixed value of $r_{e} \neq = 0$ , $n (k)$ is universal for momenta $k$ up to about $2/ r_{e}$ . An accurate relation between the energy of a two component Fermi-gas and an integral involving the density is derived. The short separation distance, $s$ , behavior of the pair density is shown to vary as $s^{6}$ .
nucl-thcond-mat.quant-gasnucl-exphysics.atm-clus+1PLB(2018)·6 citations
02
Elliptic flow of $ϕ$ -meson at intermediate $p_{T}$ : Influence of mass versus quark number
Subikash Choudhury🇮🇳 · Debojit Sarkar🇮🇳 · Subhasis Chattopadhyay🇮🇳
We have studied elliptic flow ( $v_{2}$ ) of $ϕ$ -mesons in the framework of a multi phase transport (AMPT) model at LHC energy. In the realms of AMPT model we observe $ϕ$ -mesons at intermediate transverse momentum ( $p_{T}$ ) deviate from the previously observed (at RHIC) particle type grouping of $v_{2}$ according to the number of quark content i.e, baryons and mesons. Recent results from the ALICE Collaboration have shown that $ϕ$ -meson and proton $v_{2}$ has a similar trend, possibly indicating that particle type grouping might be due to the mass of the particles and not the quark content. A stronger radial boost at LHC compared to RHIC seems to offer a consistent explanation to such observation. However, recalling that $ϕ$ -mesons decouple from the hadronic medium before additional radial flow is build-up in the hadronic phase, similar pattern in $ϕ$ -meson and proton $v_{2}$ may not be due to radial flow alone. Our study reveals that models incorporating $ϕ$ -meson production from $K K ˉ$ fusion in the hadronic rescattering phase also predict a comparable magnitude of $ϕ$ -meson and proton $v_{2}$ particularly in the intermediate region of $p_{T}$ . Whereas, $v_{2}$ of $ϕ$ -mesons created in the partonic phase is in agreement with quark-coalescence motivated baryon-meson grouping of hadron $v_{2}$ . This observation seems to provide a plausible alternative interpretation for the apparent mass-like behaviour of $ϕ$ -meson $v_{2}$ . We have also observed a violation of hydrodynamical mass ordering between proton and $ϕ$ -meson $v_{2}$ further supporting that $ϕ$ -mesons are negligibly affected by the collective radial flow in the hadronic phase due to the small in-medium hadronic interaction cross sections.
nucl-thnucl-exPRC(2017)·3 citations
03
A note on the Lipkin model in arbitrary fermion number
Y. Tsue (Kochi Univ., Japan) · C. Providencia (Univ.de Coimbra, Portugal) · J. da Providencia (Univ. de Coimbra, Portugal) · M. Yamamura (Kansai Univ., Japan)
A possible form of the Lipkin model obeying the su(6)-algebra is presented. It is a natural generalization from the idea for the su(4)-algebra recently proposed by the present authors. All the relation appearing in the present form can be expressed in terms of the spherical tensors in the su(2)-algebras. For specifying the linearly independent basis completely, twenty parameters are introduced. It is concluded that, in these parameters, the ten denote the quantum numbers coming from the eigenvalues of some hermitian operators. The five in these ten determine the minimum weight state.
nucl-thPTEP(2017)·2 citations
04
Decay width of $d^{*} (2380) \to N N π$ process in a chiral constituent quark model
Yubing Dong🇨🇳 · Fei Huang🇨🇳 · Pengnian Shen🇨🇳 · Zongye Zhang🇨🇳
The width of three-body single-pion decay process $d^{*} \to N N π^{0, \pm}$ is calculated by using the $d^{*}$ wave function obtained from our chiral SU(3) constituent quark model calculation. The effect of the dynamical structure on the width of $d^{*}$ is taken into account in both the single $ΔΔ$ channel and coupled $ΔΔ + C C$ two-channel approximations. Our numerical result shows that in the coupled-channel approximation, namely, the hidden-color configuration being considered, the obtained partial decay width of $d^{*} \to N N π$ is about several hundred $KeV$ , while in the single $ΔΔ$ channel it is just about $2 \sim 3 MeV$ . We, therefore, conclude that the partial width in the single-pion decay process of $d^{*}$ is much smaller than the widths in its double-pion decay processes. Our prediction may provide a criterion for judging different interpretations of the $d^{*}$ structure, as different pictures for the $d^{*}$ may result quite different partial decay width.
nucl-thhep-phPLB(2017)·33 citations
05
Photoproduction of $γ N \to K^{+} Σ^{*} (1385)$ in the Reggeized framework
Byung-Geel Yu🇰🇷 · Kook-Jin Kong🇰🇷
Photoproduction of $K Σ^{*} (1385)$ on the nucleon is investigated within the Regge framework and the reaction mechanism is analyzed based on the data existing in the channels $γ p \to K^{+} Σ^{* 0}$ and $γ n \to K^{+} Σ^{*-}$ . The Reggeization of the $t$ -channel meson exchanges $K (494) + K^{*} (892) + K_{2}^{*} (1430)$ is employed to construct the photoproduction amplitude. The Rarita-Schwinger formalism is applied for the spin-3/2 $^{+}$ strangeness-baryon $Σ^{*}$ with a special gauge prescription utilized for the convergence of these reaction processes. Within a set of coupling constants determined from the symmetry arguement for the $K$ and $K^{*}$ and from the duality and vector dominance for the $K_{2}^{*}$ , the data of the both processes are reproduced to a good degree. The production mechanism of these processes are featured by the dominance of the contact term plus the $K$ exchange with the role of the $K_{2}^{*}$ following rather than the $K^{*}$ .
nucl-thhep-phPRC(2017)·5 citations
06
Large single transverse spin asymmetry for forward neutrons in ultraperipheral polarized proton-nucleus collisions in explanation of measurements at RHIC-PHENIX
Gaku Mitsuka🇺🇸
The PHENIX experiment at BNL-RHIC recently reported the single transverse spin asymmetry $A_{N}$ for forward neutrons measured in polarized proton-nucleus collisions at $s_{N N} = 200$ GeV; $A_{N}$ in proton-aluminum and proton-gold collisions are -0.015 and 0.18, respectively, which are clearly different from $A_{N} = - 0.08$ in proton-proton collisions. In this paper, we propose large $A_{N}$ for forward neutrons in ultraperipheral polarized proton-nucleus collisions as an explanation of the PHENIX measurements. The proposed model is demonstrated using two Monte Carlo simulations organized as follows. In the ultraperipheral collision simulation, we use the STARlight event generator for the simulation of the virtual photon flux and then use the MAID2007 unitary isobar model for the simulation of the neutron production in the interactions of a virtual photon with a polarized proton. In the proton-nucleus hadronic interaction simulation, the differential cross sections of forward neutron production are predicted by a simple one-pion exchange model and the Glauber model. The simulated $A_{N}$ values accumulating the both contribution of ultraperipheral collisions and hadronic interactions are in good agreement with the PHENIX results.
nucl-thnucl-exPRC(2017)·16 citations
07
Feasibility Studies for Single Transverse-Spin Asymmetry Measurements at a Fixed-Target Experiment Using the LHC Proton and Lead Beams (AFTER@LHC)
Daniel Kikoła🇵🇱 · Miguel García Echevarria🇪🇸 · Cynthia Hadjidakis🇫🇷 · Jean-Philippe Lansberg🇫🇷 · Cedric Lorcé🇫🇷 · Laure Massacrier🇫🇷 · Catarina Marques Quintans🇵🇹 · Andrea Signori🇺🇸 · Barbara Trzeciak🇳🇱
The measurement of Single Transverse-Spin Asymmetries, $A_{N}$ , for various quarkonium states and Drell-Yan lepton pairs can shed light on the orbital angular momentum of quarks and gluons, a fundamental ingredient of the proton-spin puzzle. The AFTER@LHC proposal combines a unique kinematic coverage and large luminosities thanks to the Large Hadron Collider beams to deliver precise measurements, complementary to the knowledge provided by collider experiments such as at RHIC. In this paper, we report on sensitivity studies for $J / ψ$ , $Υ$ and Drell-Yan $A_{N}$ done using the performance of LHCb-like or ALICE-like detectors, combined with polarised gaseous hydrogen and helium-3 targets. In particular, such analyses will provide us with new insights and knowledge about transverse-momentum-dependent parton distribution functions for quarks and gluons and on twist-3 collinear matrix elements in the proton and the neutron.
↳ hep-exhep-phnucl-exnucl-thFew Body Syst.(2017)·44 citations
08
Heavy Flavours in Quark-Gluon Plasma
Seyong Kim🇰🇷
Recent progresses in lattice studies of heavy quark and quarkonium at non-zero temperature are discussed. Formulating a tail of spectral functions as a transport coefficient allows lattice determination of momentum diffusion coefficient ( $κ$ ) for charm quark in the heavy quark mass limit and lattice determination of heavy quark/heavy anti-quark chemical equilibration rate in NRQCD. Quenched lattice study on a large volume gives $κ / T^{3} = 1.8 \dots 3.4$ in the continuum limit. A recent study with $N_{f} = 2 + 1$ configurations estimates the charmonium chemical equilibration rate $Γ_{chem}$ . At $T = 400$ MeV with $M \sim 1.5$ GeV, $Γ_{chem}^{- 1} \sim 150$ fm/c. Earlier results from the two studies (with different lattice setups and with different Bayesian priors) which calculate bottomonium correlators using NRQCD and employ Bayesian method to calculate spectral functions are summarized: $Υ (1 S)$ survives upto $T \sim 1.9 T_{c}$ and excited states of $Υ$ are sequentially suppressed. The spectral functions of $χ_{b 1}$ channel shows a Bayesian prior dependence of its thermal behavior: the $χ_{b 1}$ spectral function with MEM prior shows melting above $T_{c}$ but that with a new Bayesian prior hints survival of $χ_{b 1}$ upto $\sim 1.6 T_{c}$ . Preliminary results from the efforts to understand the difference in the behavior of $χ_{b 1}$ spectral function is given.
↳ hep-lathep-phnucl-thPoS(2017)·3 citations
09
The $1/ N_{c}$ expansion in hadron effective field theory
Guo-Ying Chen🇨🇳
We study the $N_{c}$ scalings of pion-nucleon and nucleon-nucleon scatterings and find that a consistent large $N_{c}$ counting can be established if we assume Witten's counting rules are applied to matrix elements or scattering amplitudes which use the relativistic normalization for the nucleons. With the pionless effective field theory, we also find that the $S$ -wave nucleon-nucleon interaction is so strong that it should be treated nonperturbatively at the leading order in the $1/ N_{c}$ expansion. By summing all the leading order diagrams, we find that the deuteron binding energy is of order $1/ N_{c}$ . In contrast, meson-meson interaction is so weak that loosely-bound meson-meson molecular states may not exist in the large $N_{c}$ limit.
↳ hep-phnucl-thCommun.Theor.Phys.(2018)·4 citations
10
On the solution of linearized (linear in S-matrix) Balitsky-Kovchegov equation
Raktim Abir🇮🇳 · Mariyah Siddiqah🇮🇳
We revisited solution of a linearized form of leading order Balitsky-Kovchegov equation (linear in S-matrix for dipole-nucleus scattering). Here we adopted dipole transverse width dependent cutoff in order to regulate the dipole integral. We also have taken care of all the higher order terms (higher order in the cutoff) that have been reasonably neglected before. The solution reproduces both McLerran-Venugopalan type initial condition (Gaussian in scaling variable) and Levin-Tuchin solution (Gaussian in logarithm of scaling variable) in the appropriate limits. It also connects this two opposite limits smoothly with better accuracy for sets of rescaled rapidity when compared to numerical solutions of full leading order Balitsky-Kovchegov equation.
↳ hep-phhep-thnucl-thPRD(2017)·9 citations

Affiliations

first authorsco-authorsvia INSPIRE