## Measurement of the $_{\Lambda}^{3}H$ lifetime in Au+Au collisions at the BNL Relativistic Heavy Ion Collider

Adamczyk, L. ; Adams, J. R. ; Adkins, J. K. ; Agakishiev, G. ; Aggarwal, M. M. ; Ahammed, Z. ; Ajitanand, N. N. ; Alekseev, I. ; Anderson, D. M. ; Aoyama, R. ; Aparin, A. ; Arkhipkin, D. ; Aschenauer, E. C. ; Ashraf, M. U. ; Attri, A. ; Averichev, G. S. ; Bai, X. ; Bairathi, V. ; Barish, K. ; Behera, A. ; Bellwied, R. ; Bhasin, A. ; Bhati, A. K. ; Bhattarai, P. ; Bielcik, J.

A precise measurement of the hypertriton lifetime is presented. In this letter, the mesonic decay modes $\mathrm{{^3_\Lambda}H \rightarrow ^3He + \pi^-}$ and $\mathrm{{^3_\Lambda}H \rightarrow d + p + \pi^-}$ are used to reconstruct the hypertriton from Au+Au collision data collected by the STAR collaboration at RHIC. A minimum $χ^2$ estimation is used to determine the lifetime of $\tau = 142^{+24}_{-21}\,{\rm (stat.)} {\pm} 31\,{\rm (syst.)}$ ps. This lifetime is about 50\% shorter than the lifetime $\tau = 263\pm2$ ps of a free Λ, indicating strong hyperon-nucleon interaction in the hypernucleus system. The branching ratios of the mesonic decay channels are also determined to satisfy B.R.$_{(^3{\rm He}+\pi^-)}/$/$_{(^3{\rm He}+\pi^-)}+$$_{(d+p+\pi^-)})$) = 0.32±0.05(stat.)±0.08(syst.). Our ratio result favors the assignment $J(\mathrm{^{3}_{\Lambda}H})$ = $\frac{1}{2}$ over $J(\mathrm{^{3}_{\Lambda}H})$ = $\frac{3}{2}$. These measurements will help to constrain models of hyperon-baryon interactions.

Publication Date:
May 22 2018
Date Submitted:
Jul 01 2019
ISSN:
24699985
Citation:
Physical Review C
97
5
External Resources: