International Workshop “Search for Baryon and Lepton Number Violations”, LBLN Berkeley, International Workshop “Search for Baryon and Lepton Number Violations”, LBLN Berkeley, September 20-22September 20-22

Yuri Kamyshkov / University of Tennessee

Is (BIs (B–L) number conserved?–L) number conserved?

In regular matter (B–L) = # protons + # neutrons – # electrons 0

In the Universe most of the leptons exist as, yet undetected, relict neutrino and antineutrino radiation (similar to CMBR) and the conservation of (B–L) on the scale of the whole Universe is still an open question

(B(BL) L) 0 ; Is it a smoking gun? 0 ; Is it a smoking gun?

Fast anomalous SM interactions (sphalerons) in early Universe require that (BL) should be violated at > 10 TeV scale V. Kuzmin, V. Rubakov, M. Shaposhnikov, 1985

“Proton decay is not a prediction of baryogenesis!” [Yanagida’02]↑with conservation of (BL)

(B(B––L) : two possibilities L) : two possibilities

Possible (BPossible (BL)V manifestations following from L)V manifestations following from (B(BL)=2L)=2

B = L e.g. n or p e+ (nucleon lepton)

B = 0 ; L = 2 i.e. Majorana neutrino, 2 observable

L = 0 ; B = 2 n n oscillations

Why neutrons? Why neutrons? nnRR is a singlet part of the SM and available for is a singlet part of the SM and available for experiments while experiments while RR might be very heavy and difficult to detect might be very heavy and difficult to detect

also e.g. n + or + + (with heavy flavors involved)

All observable All observable (B(BL)=2 processes are topologically L)=2 processes are topologically similar: operators of dim-9 for non-SUSY amplitudesimilar: operators of dim-9 for non-SUSY amplitude

most promising !

There must be a scale of (BL) violation and physics

nn |B|=2 ; |(BL)|=2

There are no laws of nature that would forbid the There are no laws of nature that would forbid the N N Nbar Nbar transitions transitions except the conservation of "except the conservation of "baryon charge (number)baryon charge (number)":":

M. Gell-Mann and A. Pais, Phys. Rev. 97 (1955) 1387M. Gell-Mann and A. Pais, Phys. Rev. 97 (1955) 1387 L. Okun, Weak Interaction of Elementary Particles, Moscow, 1963L. Okun, Weak Interaction of Elementary Particles, Moscow, 1963

N N Nbar Nbar was first suggested as a possible mechanism for was first suggested as a possible mechanism for explanation of Baryon Asymmetry of Universeexplanation of Baryon Asymmetry of Universe by V. Kuzmin, 1970by V. Kuzmin, 1970

N N Nbar Nbar works within GUT + SUSY ideasworks within GUT + SUSY ideas. . First considered and First considered and developed within the framework of L/R symmetric Unification models developed within the framework of L/R symmetric Unification models by R. Mohapatra and R. Marshak, 1979 …by R. Mohapatra and R. Marshak, 1979 …

LHC nn

Low QGmodels

GeVDvali & Gabadadze (1999)

Scale improvement from new measurement

n nScales of

32 WKLB

nn nn

5 LB

GeVLB

Supersymmetric Seesaw for

B L , L R

Mohapatra & Marshak (1980)

Dutta-Mimura-Mohapatra (2005)

Non-SUSYmodels

Left-Rightsymmetric

GUTSUSYGUTPDK

Plankscale

nnnbar transition probability nbar transition probability

2 2

mixed n-nbar QM state

H Hamiltonian on the system

where and are non-relativistic energy operators:

; 2 2

n

n

n n

n n n n n nn n

n

n

E

E

E E

p pE m U E m U

m m

n n n

Important assumptions :

(i.e. T-invariance is hold)

there is a reference frame where 0

(if CPT is not violated)

gravipotential for and is the same: 0

magnetic moment as follows f

n n

n n

n

p

m m

n n ΔU U U

μ n n

rom CPT [BTW not measured!]

Earth mag. field can be screened down to accepatable few level

μ n

nT

-mixing amplitude

All beyond SMphysics is here

nnbar transition probability (for given )

nn

nnn

n

mmΔmt

V

tmV

mVtP

Vm

VmH

and ,experimentan in n timeobservatio is

tial)gravipoten ofpart or field; mag.Earth dcompensate-non todue (e.g.

neutron-anti andneutron for different potential a is where

)2(sin

)2( For

222

22

2

22

0 and 0 ns"oscillatio vacuum" theofsituation idealan In

nnnn

τ

tt

αPΔmV

]10[ timeon)(oscillatin transitiosticcharacteri is 23eVnn

"" 2 tNySensitivit n

e)flight tim of square sec,per used neutrons ofnumber ( 2tNn

Bound n: J. Chung et al., (Soudan II) Phys. Rev. D 66 (2002) 032004 > 7.21031 years

PDG 2006:Limits for both free reactor neutrons andneutrons bound inside nucleus

123

2

10 where

s~R

R freebound

Free n: M. Baldo-Ceolin et al., (ILL/Grenoble) Z. Phys C63 (1994) 409

with P = (t/free)2

Search with free neutrons is square more advantageous but Search with free neutrons is square more advantageous but with suppressed intra-nuclear transitions the larger number of with suppressed intra-nuclear transitions the larger number of neutrons can be available although with background limitationsneutrons can be available although with background limitations

(talk of A. Gal)

New SK result today

At ILL/Grenoble reactor in 89-91 by Heidelberg-ILL-Padova-Pavia Collaboration M.Baldo-Ceolin M. et al., Z. Phys., C63 (1994) 409

Previous N-Nbar search experiment with free neutrons

No background! No candidates observed.Measured limit for a year of running:

sec106.8 7nn

How one can improve on such state-of-the-art experimentHow one can improve on such state-of-the-art experiment

and achieve 3-4 orders of magnitude higher sensitivity?and achieve 3-4 orders of magnitude higher sensitivity?

Two major possible improvements:Two major possible improvements:

1.1. Focusing of neutrons: use of larger solid angle Focusing of neutrons: use of larger solid angle longer neutron flight path longer neutron flight path 1 km 1 km

2. Vertical layout: compensating Earth gravity 2. Vertical layout: compensating Earth gravity

Homestake shaftsHomestake shafts

#5; 5137#5; 5137YatesYates RossRoss

N-Nbar search experiment idea with vertical layoutN-Nbar search experiment idea with vertical layout

Not to scale

105 Pa

Neutron source needed:commercial TRIGA typesmall power 3.4 MW reactor

Search for neutron Search for neutron antineutron transitions at DUSEL antineutron transitions at DUSEL

N-Nbar proto-collaboration

February 9, 2006, Lead, SD (LOI #7) February 9, 2006, Lead, SD (LOI #7)

Goal is to build a vertical 1-km long experiment with zero background that would be factor of 1000 more sensitive than previous expt. at ILL/Grenoble

TRIGA Cold Vertical Beam, 3 years

Cold Beam

TRIGA Very Cold Vertical Beam, 3 years

Super-K’07

Spare slides

calculated by Ken Ganezer