“Forbidden decays in 2014: material for

discussion”

Gianluca Lamanna & Tommaso Spadaro (Pisa & LNF)

PhysSensy - NA62 Liverpool Meeting 28.08.2012

DISCLAIMER:

PUT A BIG

~IN FRONT ANY NUMBER

• Figure of merit (according to Giuseppe)– 10% of nominal intensity:

• On average, due to different reasons (technical, detectors, problems,…)– 60 days of data taking:

• Very good data taking efficiency (good SPS, effective runs, …)– 10 KHz of data written on disk:

• No limitation from the infrastructure

2014

Interesting forbidden decays (1)

Process Motivation

Present limit

Experiment

K+→p+m+e- LF < 1.3 x 10-11

E865K+→p+m-e+ LF < 5.2 x 10-10

K+→p-m+e+ LF , LN < 5.0 x 10-10

K+→p-e+e+ LN < 6.4 x 10-10

K+→p-m+m+ LN < 1.1 x 10-9 NA48/2K+→m- ne+e+ LN < 2.0 x 10-8 Geneva-SaclayK+→p+p+e-n DS!=DQ < 1.2 x 10-8 Bloch et al.

(1976)K+→p+p+m-n DS!=DQ < 3.0 x 10-6 Birge et al.

(1965)K+→p+g Angular

momentum< 2.3 x 10-9 E949

K+→p+X0 NP < 5.9 x 10-11 mX0=0 E787,E949K+→p+ cc NP -- E949

Interesting forbidden decays (2)

Process Motivation Present limit

experiment

p0→m-e+ LF < 3.4 x 10-9 KTEVp0→m+e- LF < 3.8 x 10-10

p+→m-e+e+n LF <1.6x10-6 JINR-SPECp0→eeg Dark Force Next slide --p0→ee Dark Force (6.46+-0.33)x10-8 KTEVp0→eeee T viol. in SI and EI C=-0.77+-0.53 Samios et al.p0→ggg C violation < 3.1 x 10-8 Crystal Boxp0→gggg light scalar < 2 x 10-8 Crystal Boxp0→nn̅ RH neutrino <2.7x10-7 E949Axions CP problem <4.5x10-7 BNL-87Sterile neutrino n problems -- --sgoldstino NP SUSY 214 MeV (3 events) HyperCP

NA62 prospects

• * Rough estimation• ** See Evgueni

Process Present

Acceptance* 2014 >2014

K+→p+m+e- < 1.3 x 10-11 15%** <10-10 <1.3x10-12

K+→p+m-e+ < 5.2 x 10-10 15%** <10-10 <1.3x10-12

K+→p-m+e+ < 5.0 x 10-10 15%** <10-10 <1.3x10-12

K+→p-e+e+ < 6.4 x 10-10 15%** <10-10 <1.3x10-12

K+→p-m+m+ < 1.1 x 10-9 15%** <10-10 <1.3x10-12

K+→m- ne+e+ < 2.0 x 10-8 2% <2x10-10 <10-11

K+→p+p+e-n < 1.2 x 10-

82% <2x10-10 <10-11

K+→p+p+m-n < 3.0 x 10-

62% <2x10-10 <10-11

K+→p+g < 2.3 x 10-

930% <1x10-11 <10-12

K+→p+X0 < 5.9 x 10-11 30% <10-11 <10-12

K+→p+ cc <10-10 15% <10-10 <10-12

NA62 prospects

• * assuming 20% trigger efficiency• ** assuming 1% trigger efficiency

Process Present Accep. 2014 >2014

p0→m-e+ < 3.4 x 10-9 2% <2x10-10 <10-11

p0→m+e- < 3.8 x 10-10 2% <2x10-10 <10-11

p+→m-

e+e+n<1.6x10-6 2% <2x10-10 <10-11

p0→ee(g) --- 2% 107 dalitz events 2x108 dalitz events

p0→ee (6.46+-0.33)x10-8

2% 100 events 2500 events

p0→eeee C=-0.77+-0.53 1% 5x104 events 106 events

p0→ggg < 3.1 x 10-8 1% <10-9* <10-10

p0→gggg < 2 x 10-8 1% <10-9* <10-10

p0→nn̅ <2.7x10-7 15% <3x10-9 ** <10-10

Axions (ee) <4.5x10-7 2% <2x10-10 <10-11

Sterile n -- -- -- --

Sgoldstino 3 evts at 214 MeV

10% 5x108 events ( 0 0pp p )

1010 events ( 0 0pp p )

The L0 Bandwidth

• Assuming 1 MHz L0 readout bandwidth there are 600 kHz for:– Control triggers– Triggers to study detectors and background– Calibration & random– Other rare kaon decays (K->pp0g, K->pp0ee, Ke4n, …)

– Forbiddens and exotics Kaon and p0

pnn

1 MHz

• Main trigger pnn:– Q1*RICH*!MUV3*!LKR*!LAV

320 kHz– Q1*RICH*!LKR*!LAV*!

MIP*ETOT380kHz• Let me assume that the total pnn

trigger rate is 400 kHz.• Let me assume that at L1/L2 we will

have additional 10/10 reduction factors.

[All numbers from Spasimir]

Filling the L0: Q1/DWpnn 40% 400 kHz

1trk 56% 560 kHz

3trk 4% 4 kHz

tot 100% 1 MHz

pnn

3trk

1trk

L0 : pnn .OR. Q1/DW (DW=13)

3p: 96%

ppD: 4%

Km2: 42%

pp0: 21%Halo: 28%

Other: 9%

• Very inefficient L0 for most of the decays– Big downscaling– 42% of Q1 coming from

Halo+Km2

– Only the 70% of the Q1 from decays are in the decay region.

• Change approach– Consider selective trigger

for physics– Maintain a «quota» of

generic (Q1) 1trk and 3trks decays for detector study

pnn

Halo+Km2In decay region

Forbiddens and exotics

1 trk

3 trks

multi trks

LFV (pme), p0->me, dark photon, Axions, p0->ee, sgoldstino

K-> , -> , -pg p ggg p> , -> , gggg p nn sgoldstino

-p >eeee

Forbidden 1 trk: F1TRK• L0:

– the main trigger (pnn) has some efficiency for F1TRK decays (ex: 40% for K->pg,100% for p0->nn)

– Dedicated F1TRK: Q1*RICH32*!MUV3*!LAV is the starting point (500kHz). Tight !MIP*ETOT*NLKR?

– RICHGPU: reconstruct the missing mass of the p+ (Elena)

• L1/2: decay vertex+LKr• Some studies already done by Tommaso and Elisa:

– p0->3 g 4kHz (28%)– p0->4 g 17 kHz (18%)

7.2 MHz

50 kHz 1 kHzL1/L2L0

Proposal:

Forbidden 3 trks: F3TRK

• L0:– Starting point Q1*RICH>20*!LAV (>1 MHz)– Possibility to exploit the asymmetry on the RICH illumination to trigger

on three tracks (P.Cooper – note (draft))– Define triggers exploiting event topology and different detectors

dilepton triggers (Evgueni), Dark Photon (Bruno), …– Attempt to have a single strobe to L1 using GPU (next slide)

• Higher efficiency (to be studied)• Smaller use of the L0 bandwidth

• L1/L2: decay vertex+PID+Total Energy+…

0.5 MHz

50 kHz 1 kHzL1/L2L0

Proposal:

example

• If for (mp,mp,mp) A is close to the transverse momentum of the kaon the event will be rejected

• Simulation needed to understand resolution, rejection power and efficiency.

1

2

3

For each 3 rings event build the following quantities:

𝐴 𝑗=∑ 𝑌 𝑐𝑒𝑛𝑡𝑒𝑟 𝑖∗ 𝑅𝑖∗𝑚𝑖 , 𝑗Where (m1, m2, m3) are the particles masses mp,mm,me

Two scenarios

• High intensity– Standard trigger configuration:

pnn + F1TRK + F3TRK + FMTRK + OTHER/D1 + Q1/D2 + NHOD/D3 + CAL + RND

• Low intensity (10%)– In principle it’s possible to think about an alternative trigger

scheme (either changing D1,D2,D3 or changing cuts in order to increase the single trigger efficiency)

pnn

pnn

Q1/50Q1/50

F1/3TRKF1/3TRK

Conclusions

• Assuming limited statistics in 2014, we will be competitive only on few forbidden decay modes.

• Dedicated triggers to collect Forbiddens and exotics:– Significant overlap with other triggers for physics and

trigger for detector studies

• In any case to study high efficiency low bandwidth dedicated parasitic triggers (for any channels), we could profit from the first phase of data collection. – It’s not a loss of time to collect data for all the decay

modes.