Yuri Kamyshkov/ University of Tennessee Mini-Workshop, WU St. Louis, February 11, 2011

n  nbar transition probability  -mixing amplitude All beyond SM physics is here 

n  nbar transition probability (for given  )

Suppression of n  nbar in intranuclear transitions (Friedman and Gal, 2008)

General approach: one of the neutrons in the nucleus transforms to anti-neutron and the latter is annihilated with other nucleons to pions

Sensitivity for free neutron search (appearance probability) Sensitivity for bound neutron search (in nucleon decay expts) Will use ILL experiment limit as a unit of sensitivity = 1u Corresponds to sensitivity = 16u

Important to know theoretical uncertainty Important to know theoretical uncertainty Is nuclear theory reliable? complete? Is nuclear theory reliable? complete? intranuclear search experiments: Super-K, Soudan-2 Frejus Free neutron search limit (ILL)

ExperimentYearA n  year (10 32 ) Det. eff.Candid.Bkgr.  nucl, yr (90% CL) Kamiokande1986O3.033%00.9/yr >0.43  Frejus1990Fe5.030%04 >0.65  Soudan-22002Fe21.918%54.5 >0.72  Super-K*2007O % >1.8  Super-K *2009O %2324 >1.97  SNO *2010D0.5441%24.75 >0.301  * Not yet published Observed improvement weaker than SQRT is due to irreducible background of atmospheric ’s. Still possible to improve a limit (though slowly) but impossible to claim a discovery.

ExperimentYearA  nucl, yr (90% CL) R(old), s  1 R(new), s  1  (old), s  (new), s Kamiokande1986O >0.43    >1.2  10 8 >1.65  10 8 Frejus1990Fe >0.65   ? >1.2  10 8 ? Soudan-22002Fe >0.72   ? >1.3  10 8 ? Super-K*2007O >1.77    >2.36  10 8 >3.34  10 8 Super-K *2009O >1.97    >2.5  10 8 >3.53  10 8 SNO *2010D >0.301    >1.96  10 8 >3.4  10 8 V. Kopeliovich 2010, Deuterium Friedman and Gal 2008, Oxygen Dover, Gal et. al, old

Claudio Ciofi degli Atti (Perugia U.) is going to look at this (January 2011)

Proposed by Stuart Raby (2010) overlap of two quarks wavefunctions is more probable than for 3 quarks such 2 quarks might be coming from proton (not only neutron) 4-antiquark final state annihilates faster

All these processes governed by the same crossing amplitude can result into the same indistinguishable final state (of ~ 5 pions)  Existing intranuclear NNbar limits will need to be re-evaluated

More on n  nbar suppression: sensitivity to CPT violation Following Yu. Abov, F. Djeparov, and L. Okun, Pisma ZhETF 39 (1984) 493 Transitions for free neutrons V=0 are suppressed when Suppression possible if  m >  (due to CPT violation) In the intranuclear transitions where V~10 MeV small provides no Intranuclear transitions additional suppression. Intranuclear transitions are not sensitive to  m ! are not sensitive to  m ! Valid only if  0, i.e. if n  nbar transformation exist

 m (V=0) vs  in N  Nbar search (if  0) Experimental limits on mass difference Uncertainty of intranuclear suppression If N  Nbar transition will be observed this will be a new limit of CPT  m test