arXiv subjects

M. R. Hadizadeh

Publications and source records attributed to M. R. Hadizadeh.

At least 37 records · Page 2Linked to original sources

arXiv2015

The Relativistic Three-Body Bound State in Three-Dimensions

Studying of the relativistic three-body bound state in a three-dimensional (3D) approach is a necessary first step in a process to eventually perform scattering calculations at GeV energies, where partial-wave expansions are not useful. To this aim we recently studied relativistic effects in the binding energy and for the first time, obtained the relativistic 3B wave function \cite{Hadizadeh_PRC90}. The relativistic Faddeev integral equations for the bound state are formulated in terms of momentum vectors, and relativistic invariance is incorporated within the framework of Poincaré invariant quantum mechanics.

nucl-th↗

arXiv2015

Description of Heavy Quark $\overline{MS}$ Mass by Lippmann Schwinger Equation

Quark masses are of great prominence in high-energy physics. In this paper, we have studied the heavy meson systems via solving the Lippmann-Schwinger equation by using the Martin potential for heavy quark masses. We have also attempted to use Martin potential to find an acceptable mass spectrum for heavy quarkonia. We obtained this spectrum via minimal phenomenological model (M. Melles, Phys. Rev. D \textbf{62}: 074019 2000). The mass spectra for $b\bar{b}$ and $c\bar{c}$ are calculated without taking into account the relativistic corrections and spin-dependent effects. The obtained mass spectra turn out to fit the experimental findings. By using the conventional spectrum, we extract the pole mass of heavy quarks and use it along with the relation between $\overline{MS}$ mass (modified minimal subtraction scheme) and the on-shell quark mass to find $\overline{MS}$ mass for these quarks. The obtained results for $\overline{MS}$ mass are in good agreement with corresponding values reported in the literature.

hep-ph↗

arXiv2015

Heavy Mesons Spectroscopy

In this paper, we use Martin and Coulomb-Linear potentials and solve Lippman-Schwinger equation and then identify $b\bar{c}$ energy levels. Moreover, we predict results for such energy levels as that of $t\bar{t}$ (in its short half-life) which is not observed. We showed our results are consistent with previous findings in literature. Also investigating spectrum of eigen-values, we obtain stability interval for Yukawa-Linear potential.

hep-ph↗

arXiv2015

Comment on "Tetraquarks as diquark-antidiquark bound systems"

The author argues that the calculated masses of heavy tetraquarks obtained by solution of the spin-independent homogeneous Lippmann-Schwinger integral equation in a diquark-antidiquark picture reported by M. Monemzadeh et al., Phys. Lett. B {\bf741}, 124 (2015), are incorrect. We have reexamined all of the published results and we believe that not only the reported tetraquark masses for states with zero total angular momentum are incorrect, the reported masses for states with non-zero total angular momentum are quite misleading, because these states cannot be predicted by a spin-independent formalism.

hep-ph↗

arXiv2014

The Relativistic Three-Body Bound State in a 3D Formulation

Background: The relativistic three-body problem has a long tradition in few-nucleon physics. Calculations of the triton binding energy based on the solution of the relativistic Faddeev equation in general lead to a weaker binding than the corresponding non-relativistic calculation. Purpose: In this work we solve for the three-body binding energy as well as the wave function and its momentum distribution. The effect of the different relativistic ingredients are studied in detail. Method: Relativistic invariance is incorporated within the framework of Poincar{é} invariant quantum mechanics. The relativistic momentum-space Faddeev equation is formulated and directly solved in terms of momentum vectors without employing a partial-wave decomposition. Results: The relativistic calculation gives a three-body binding energy which is about 3% smaller than its non-relativistic counterpart. In the wave function, relativistic effects are manifested in the Fermi motion of the spectator particle. Conclusions: Our calculations show that though the overall relativistic effects in the three-body bound state are small, individual effects by themselves are not necessarily small and must be taken into account consistently.

nucl-th↗

arXiv2014

Three-Body Bound State Calculations by Using Three-Dimensional Low Momentum Interaction $V_{low-k}$

Three-dimensional (3D) Faddeev integral equations are solved for three-body (3B) bound state problem without using the partial wave (PW) form of low momentum two-body (2B) interaction $V_{low-k}$ which is constructed from spin independent Malfliet-Tjon V (MT-V) potential. The dependence of 3B binding energy on the cutoff momentum of $V_{low-k}$ is investigated for a wide range of $Λ$ from $1.0$ to $7.0\, fm^{-1}$. The properties of Faddeev components and 3B wave function are displayed and the effect of number of grid points for momentum and angle variables on the accuracy and the stability of numerical results is studied by calculation of the expectation value of total Hamiltonian.

nucl-th↗

arXiv2013

Effective range from tetramer dissociation data for cesium atoms

The shifts in the four-body recombination peaks, due to an effective range correction to the zero-range model close to the unitary limit, are obtained and used to extract the corresponding effective range of a given atomic system. The approach is applied to an ultracold gas of cesium atoms close to broad Feshbach resonances, where deviations of experimental values from universal model predictions are associated to effective range corrections. The effective range correction is extracted, with a weighted average given by 3.9$\pm 0.8 R_{vdW}$, where $R_{vdW}$ is the van der Waals length scale; which is consistent with the van der Waals potential tail for the $Cs_2$ system. The method can be generally applied to other cold atom experimental setups to determine the contribution of the effective range to the tetramer dissociation position.

cond-mat.quant-gas↗

arXiv2012

Universality in Four-Boson Systems

We report recent advances on the study of universal weakly bound four-boson states from the solutions of the Faddeev-Yakubovsky equations with zero-range two-body interactions. In particular, we present the correlation between the energies of successive tetramers between two neighbor Efimov trimers and compare it to recent finite range potential model calculations. We provide further results on the large momentum structure of the tetramer wave function, where the four-body scale, introduced in the regularization procedure of the bound state equations in momentum space, is clearly manifested. The results we are presenting confirm a previous conjecture on a four-body scaling behavior, which is independent of the three-body one. We show that the correlation between the positions of two successive resonant four-boson recombination peaks are consistent with recent data, as well as with recent calculations close to the unitary limit. Systematic deviations suggest the relevance of range corrections.

cond-mat.quant-gas↗

arXiv2012

Binding and structure of tetramers in the scaling limit

The momentum-space structure of the Faddeev-Yakubovsky (FY)components of weakly-bound tetramers is investigated at the unitary limit using a renormalized zero-range two-body interaction. The results, obtained by considering a given trimer level with binding energy $B_3$, provide further support to a universal scaling function relating the binding energies of two successive tetramer states. The correlated scaling between the tetramer energies comes from the sensitivity of the four-boson system to a short-range four-body scale. Each excited $N-$th tetramer energy $B_4^{(N)}$ moves as the short-range four-body scale changes, while the trimer properties are kept fixed, with the next excited tetramer $B_4^{(N+1)}$ emerging from the atom-trimer threshold for a universal ratio $B_4^{(N)}/B_3 = B_4^ {(N)}/B_4^{(N+1)} \simeq 4.6$, which does not depend on $N$. We show that both channels of the FY decomposition [atom-trimer ($K-$type) and dimer-dimer ($H-$type)] present high momentum tails, which reflect the short-range four-body scale. We also found that the $H-$channel is favored over $K-$channel at low momentum when the four-body momentum scale largely overcomes the three-body one.

cond-mat.soft↗

arXiv2011

Solution of Two-Body Bound State Problems with Confining Potentials

The homogeneous Lippmann-Schwinger integral equation is solved in momentum space by using confining potentials. Since the confining potentials are unbounded at large distances, they lead to a singularity at small momentum. In order to remove the singularity of the kernel of the integral equation, a regularized form of the potentials is used. As an application of the method, the mass spectra of heavy quarkonia, mesons consisting from heavy quark and antiquark $(Υ(b\bar{b}), ψ(c\bar{c}))$, are calculated for linear and quadratic confining potentials. The results are in good agreement with configuration space and experimental results.

hep-ph↗

arXiv2011

Solutions of the bound state Faddeev-Yakubovsky equations in three dimensions by using NN and 3N potential models

A recently developed three-dimensional approach (without partial-wave decomposition) is considered to investigate solutions of Faddeev-Yakubovsky integral equations in momentum space for three- and four-body bound states, with the inclusion of three-body forces. In the calculations of the binding energies, spin-dependent nucleon-nucleon (NN) potential models (named, S$_{3}$, MT-I/III, YS-type and P$_{5.5}$GL) are considered along with the scalar two-meson exchange three-body potential. Good agreement of the presently reported results with the ones obtained by other techniques are obtained, demonstrating the advantage of an approach in which the formalism is much more simplified and easy to manage for direct computation.

nucl-th↗

arXiv2011

Universality and scaling limit of weakly-bound tetramers

The occurrence of a new limit cycle in few-body physics, expressing a universal scaling function relating the binding energies of two consecutive tetramer states, is revealed, considering a renormalized zero-range two-body interaction applied to four identical bosons. The tetramer energy spectrum is obtained when adding a boson to an Efimov bound state with energy $B_3$ in the unitary limit (for zero two-body binding, or infinite two-body scattering length). Each excited $N-$th tetramer energy $B_4^{(N)}$ is shown to slide along a scaling function as a short-range four-body scale is changed, emerging from the 3+1 threshold for a universal ratio $B_4^ {(N)}/B_3 \simeq 4.6$, which does not depend on $N$. The new scale can also be revealed by a resonance in the atom-trimer recombination process.

physics.atm-clus↗

arXiv2010

3D calculation of Tucson-Melbourne 3NF effect in triton binding energy

As an application of the new realistic three-dimensional (3D) formalism reported recently for three-nucleon (3N) bound states, an attempt is made to study the effect of three-nucleon forces (3NFs) in triton binding energy in a non partial wave (PW) approach. The spin-isospin dependent 3N Faddeev integral equations with the inclusion of 3NFs, which are formulated as function of vector Jacobi momenta, specifically the magnitudes of the momenta and the angle between them, are solved with Bonn-B and Tucson-Melbourne NN and 3N forces in operator forms which can be incorporated in our 3D formalism. The comparison with numerical results in both, novel 3D and standard PW schemes, shows that non PW calculations avoid the very involved angular momentum algebra occurring for the permutations and transformations and it is more efficient and less cumbersome for considering the 3NF.

nucl-th↗

arXiv2010

Toward the Application of Three-Dimensional Approach to Few-body Atomic Bound States

The first step toward the application of an effective non partial wave (PW) numerical approach to few-body atomic bound states has been taken. The two-body transition amplitude which appears in the kernel of three-dimensional Faddeev-Yakubovsky integral equations is calculated as function of two-body Jacobi momentum vectors, i.e. as a function of the magnitude of initial and final momentum vectors and the angle between them. For numerical calculation the realistic interatomic interactions HFDHE2, HFD-B, LM2M2 and TTY are used. The angular and momentum dependence of the fully off-shell transition amplitude is studied at negative energies. It has been numerically shown that, similar to the nuclear case, the transition amplitude exhibits a characteristic angular behavior in the vicinity of 4He dimer pole.

physics.atom-ph↗

arXiv2010

Photodisintegration of $^3H$ in a three dimensional Faddeev approach

An interaction of a photon with $^3H$ is invstigated based on a three dimensional Faddeev approach. In this approach the three-nucleon Faddeev equations with two-nucleon interactions are formulated with consideration of the magnitude of the vector Jacobi momenta and the angle between them with the inclusion of the spin-isospin quantum numbers, without employing a partial wave decomposition. In this formulation the two body t-matrices and triton wave function are calculated in the three dimensional approach using AV18 potential. In the first step we use the standard single nucleon current in this article.

nucl-th↗

arXiv2009

The three dimensional calculations of NN bound and scattering states with chiral potential up to N3LO

The recently developed chiral nucleon-nucleon ($NN$) potential by Epelbaum \emph{et al.} has been employed to study the two-nucleon bound and scattering states. Chiral $NN$ potential up to next-to-next-to-next-to leading order (N$^3$LO) is used to calculated the np differential cross section and deuteron binding energy in a realistic three dimensional approach. The obtained results based on this helicity representation are compared to the standard partial wave (PW) results. This comparison shows that the 3D approach provides the same accuracy in the description of $NN$ observables and the results are in close agreement with available experimental data.

nucl-th↗

arXiv2008

A Realistic Formalism for 4N Bound State in a Three-Dimensional Yakubovsky Scheme

A spin-isospin dependent Three-Dimensional formalism based on the momentum vectors for the four-nucleon bound state is presented. The four-nucleon Yakubovsky equations with two- and three-nucleon interactions are formulated as a function of the vector Jacobi momenta. Our formalism, according to the number of spin-isospin states that one takes into account, leads to only a strictly finite number of the coupled three-dimensional integral equations to be solved. The evaluation of the transition and permutation operators as well as the coordinate transformations due to considering the continuous angle variables instead of the discrete angular momentum quantum numbers are less complicated in comparison with partial wave representation. With respect to partial wave the present formalism with the smaller number of equations leads to higher dimensionality of the integral equations. We have concluded that Three-Dimensional formalism is less cumbersome for considering the three-nucleon forces.

nucl-th↗

arXiv2008

Towards a three dimensional solution for 3N bound states with 3NFs

After a brief discussion about the necessity of using the 3D approach, we present the non PW formalism for 3N bound state with the inclusion of 3N force (3NF). As an example the evaluation of 3NF matrix elements, which appear in the obtained coupled three dimensional integral equations, for $2π$-exchange Tucson-Melbourne 3NF show how would be this formalism efficient and less cumbersome in comparison with the PW formalism.

nucl-th↗