The effect of van der Waals forces in two-atomic elastic collision

The s-wave elastic phase-shifts and s-wave elastic cross sections are studied to find the effect of long-range forces on cold-atomic interactions using a modified static-exchange model for Ps-H system. Preliminary results are being reported.

arXiv:1103.4915Journal of Physics Conference SeriesNov 5, 20123 citations

Low-energy universality and scaling of van der Waals forces

A. Calle Cordón, E. Ruiz Arriola

arXiv:0912.1714Physical Review AApr 23, 201018 citations

The effect of van der Waals forces in two-atomic elastic collision

Hasi Ray

Published Aug 8, 2013• 0 citations

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Abstract

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The Effect of van der Waals interaction in Elastic Collision between Ps(1s) and H(1s)

Hasi Ray, Anuradha De, Deparpita Ray

The modified static exchange model (MSEM) recently introduced by Ray [1] to study two-atomic collision processes at low and cold-energies, is used for detailed analysis of the long-range effects due to induced dipole-dipole van der Waals interaction between Ps and H atoms. The MSEM includes the non-adiabatic short-range effect due to electron-exchange and the long-range effect due to induced dynamic dipole polarisabilities of the atoms. The effective interatomic potential is highly sensitive to the minimum distance between the atoms ( ). The s-, p- and d- wave elastic phase shifts, corresponding partial cross sections, the scattering length and effective ranges are calculated and studied with the variation of the chosen least interatomic distance between them. It is found that the scattering length is highly sensitive to the effective interatomic potential that depends on the least interatomic distance. In addition the studies are made in search of Feshbach resonances. The observed interesting feature with the variation of in the triplet channel invites more accurate investigations if new physics.The modified static exchange model (MSEM) recently introduced by Ray [1] to study two-atomic collision processes at low and cold-energies, is used for detailed analysis of the long-range effects due to induced dipole-dipole van der Waals interaction between Ps and H atoms. The MSEM includes the non-adiabatic short-range effect due to electron-exchange and the long-range effect due to induced dynamic dipole polarisabilities of the atoms. The effective interatomic potential is highly sensitive to the minimum distance between the atoms ( ). The s-, p- and d- wave elastic phase shifts, corresponding partial cross sections, the scattering length and effective ranges are calculated and studied with the variation of the chosen least interatomic distance between them. It is found that the scattering length is highly sensitive to the effective interatomic potential that depends on the least interatomic distance. In addition the studies are made in search of Feshbach resonances. The observed interesting feature with the variation of in the triplet channel invites more accurate investigations if new physics.

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The atom and atom scattering model to control ultracold collisions

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A modified static exchange model is introduced, it could be useful to control the elastic s-wave scattering length in studying cold-atomic interaction. The theory includes the long-range van der Waals interaction in addition to short-range exchange force. The model is applied on Ps-H system to study the Feshbach resonances e.g. the s-wave elastic phase shifts and the corresponding cross sections at ultracold energies. These are compared with the data obtained using the static exchange model. A very interesting features are observed when we vary the interatomic separation i.e. the strength of dipole-dipole interaction.A modified static exchange model is introduced, it could be useful to control the elastic s-wave scattering length in studying cold-atomic interaction. The theory includes the long-range van der Waals interaction in addition to short-range exchange force. The model is applied on Ps-H system to study the Feshbach resonances e.g. the s-wave elastic phase shifts and the corresponding cross sections at ultracold energies. These are compared with the data obtained using the static exchange model. A very interesting features are observed when we vary the interatomic separation i.e. the strength of dipole-dipole interaction.

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The effect of long-range forces on cold-atomic interactions

Hasi Ray, Anuradha De

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Low-energy universality and scaling of van der Waals forces

A. Calle Cordón, E. Ruiz Arriola

At long distances, interactions between neutral ground-state atoms can be described by the van der Waals potential. In the ultracold regime, atom-atom scattering is dominated by $s$ -waves phase shifts given by an effective range expansion in terms of the scattering length ${\ensuremath{\alpha}}_{0}$ and the effective range ${r}_{0}$ . We show that while the scattering length cannot be predicted for these potentials, the effective range is given by the universal low-energy theorem ${r}_{0}=A+B/{\ensuremath{\alpha}}_{0}+C/{\ensuremath{\alpha}}_{0}^{2}$, where $A$ , $B$ , and $C$ depend on the dispersion coefficients ${C}_{n}$ and the reduced diatom mass. We confront this formula to about 100 determinations of ${r}_{0}$ and ${\ensuremath{\alpha}}_{0}$ and show why the result is dominated by the leading dispersion coefficient ${C}_{6}$ . Universality and scaling extend much beyond naive dimensional analysis estimates.At long distances, interactions between neutral ground-state atoms can be described by the van der Waals potential. In the ultracold regime, atom-atom scattering is dominated by $s$-waves phase shifts given by an effective range expansion in terms of the scattering length ${\ensuremath{\alpha}}_{0}$ and the effective range ${r}_{0}$. We show that while the scattering length cannot be predicted for these potentials, the effective range is given by the universal low-energy theorem ${r}_{0}=A+B/{\ensuremath{\alpha}}_{0}+C/{\ensuremath{\alpha}}_{0}^{2}$, where $A$, $B$, and $C$ depend on the dispersion coefficients ${C}_{n}$ and the reduced diatom mass. We confront this formula to about 100 determinations of ${r}_{0}$ and ${\ensuremath{\alpha}}_{0}$ and show why the result is dominated by the leading dispersion coefficient ${C}_{6}$. Universality and scaling extend much beyond naive dimensional analysis estimates.

arXiv:0912.1714Physical Review AApr 23, 201018 citations

At long distances, interactions between neutral ground-state atoms can be described by the van der Waals potential. In the ultracold regime, atom-atom scattering is dominated by

s

-waves phase shifts given by an effective range expansion in terms of the scattering length ${\ensuremath{\alpha}}_{0}$ and the effective range

{r}_{0}

. We show that while the scattering length cannot be predicted for these potentials, the effective range is given by the universal low-energy theorem ${r}_{0}=A+B/{\ensuremath{\alpha}}_{0}+C/{\ensuremath{\alpha}}_{0}^{2}$, where

A

B

, and

C

depend on the dispersion coefficients

{C}_{n}

and the reduced diatom mass. We confront this formula to about 100 determinations of

{r}_{0}

and ${\ensuremath{\alpha}}_{0}$ and show why the result is dominated by the leading dispersion coefficient

{C}_{6}

. Universality and scaling extend much beyond naive dimensional analysis estimates.