Realistic nuclear interactions and the problem of the radiocarbon dating beta decay Jeremy W. Holt* * Thesis Advisor: Gerry Brown (+ Tom Kuo) Nuclear Theory Group

The Nuclear Force Parameterize with meson exchange 1 fm 1 Ångstrom 1 fm = 1  10 –15 m 1 Ångstrom = 1  10 –10 m thumb/f/fd/300px-Helium_atom_QM.svg.png

Two-body interactions alone cannot describe saturation point Nuclear matter saturation A   and V   A nucleons in a volume V A/V = n (constant) n Z. Li et al., PRC 74 (2006)

Hadronic mass generated dynamically e4948/e4950/e4963/e4965/hera_proton_ger.jpg u and d quark masses: 5 – 10 MeV/c 2 p and n masses: 950 MeV/c 2

Original Brown-Rho scaling G. Brown and M. Rho, PRL 66 (1991) 2720 Tensor force In-medium nuclear force

Problem 11 C  11 B + e MeV 20.4 min Decay mode Decay energy Half-life 13 N  13 C + e MeV 10.0 min 14 O  14 N + e MeV 1.18 min 15 O  15 N + e MeV 2.04 min 14 C  14 N + e – MeV 2  10 9 min All allowed decays

Radiocarbon Dating

Carbon-14 continuously replenished in atmosphere Half-life of carbon-14 is 5760 years Can date objects up to about 50,000 years old Invented in 1949 by Willard Libby at the University of Chicago Revolutionized absolute archaeological dating Nobel Prize in Chemistry 1960 for invention of radiocarbon dating

8 neutrons 6 protons 7 neutrons 7 protons Carbon-14Nitrogen-14 Beta-minus Decay AntineutrinoElectron –– : Nuclear physics still in infancy 1950’s: Nuclear shell model developed Predictions showed that the decay should not be suppressed How to calculate the lifetime of Carbon-14

14 C 14 N (J ,T) = (0 +,1) (J ,T) = (1 +,0) –– Gamow-Teller matrix element highly sensitive to nuclear tensor force

Results Suppression due largely to decreasing tensor force Archaeologically long half-life for densities ~ n 0 J. W. Holt et al., PRL 100 (2008)

“A new calculation explains the mechanism behind carbon dating” --Physics News Update, Number 854 #1, January 23, 2008 by Phil Schewe “Solving the carbon-14 mystery” --ScienceNOW Daily News, January 28, 2008, by Phil Berardelli “Unravelling carbon’s chemical secrets” --NatureNews, February 1, 2008, by Rachel Courtland “Chance structure makes carbon dating possible” --PhysicsWorld.com, January 31, 2008, by Belle Dumé