and NA62 (Neutral Pion Form Factor) On behalf of the NA62 - - PowerPoint PPT Presentation

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Recent results from NA48/2 (LFV, DP) and NA62 (Neutral Pion Form Factor) On behalf of the NA62 collaboration Nicolas Lurkin School of Physics and Astronomy, University of Birmingham XIIIth International Conference on Heavy Quarks and Leptons,

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SLIDE 1

Recent results from NA48/2 (LFV, DP) and NA62 (Neutral Pion Form Factor)

Nicolas Lurkin

School of Physics and Astronomy, University of Birmingham XIIIth International Conference on Heavy Quarks and Leptons, 24-05-2016

On behalf of the NA62 collaboration

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SLIDE 2

Outline

Nicolas Lurkin, HQL2016,24-05-2016 2

 NA48/2 - πŽππŸ•πŸ‘π’π‹ experiment  Lepton Number Violating (LNV) decay 𝑳± β†’ π†βˆ“π‚Β±π‚Β±  Search for resonances in 𝑳± β†’ π†βˆ“π‚Β±π‚Β± and 𝑳± β†’ 𝝆±𝝂+π‚βˆ’  Dark Photon (DP) searches in π†πŸ decay  π†πŸ electromagnetic transition form factor (TFF) measurement

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SLIDE 3

CERN NA48/NA62 experiments

NA48/NA62: Centre of the LHC Jura mountains

France

Geneva airport

Switzerland

LHC SPS Experiments history Earlier NA31 1997 2001 NA48 (𝐿𝑇/𝐿𝑀) 𝑆𝑓 πœβ€²/𝜁 Discovery of direct CPV 2002 NA48/1 (𝐿𝑇/hyperons) Rare 𝐿𝑇 and hyperon decays 2003 2004 NA48/2 (𝐿+/πΏβˆ’) Direct CPV, Rare 𝐿+/πΏβˆ’ decays 2007 2008 NA62RK (𝐿+/πΏβˆ’) 𝑆𝐿 = 𝐿𝑓2

± /𝐿 𝜈2 ±

2014 NA62 (𝐿+) 𝐿+ β†’ 𝜌+πœ‰ πœ‰, Rare 𝐿+ and 𝜌0 decays

Kaon decay in flight experiment NA62: currently ~200 participants, 29 institutions from 13 countries

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SLIDE 4

Experimental Setup (NA48/2 – πŽππŸ•πŸ‘π’π‹)

Nicolas Lurkin, HQL2016,24-05-2016 4

 Principal subdetectors

  • Scintillator hodoscope (HOD)
  • Low-level trigger,

time measurement (150 ps)

  • Magnetic spectrometer (4DHCs)
  • 4 views/DCH high efficiency
  • πœπ‘ž π‘ž = 1.02% βŠ• 0.044% β‹… π‘ž [GeV/c]

NA48/2 = 0.48% βŠ• 0.009% β‹… π‘ž [GeV/c] NA62RK

  • Liquid Krypton EM calorimeter (LKr)
  • High granularity, quasi-homogeneous
  • 𝜏𝐹 𝐹 =

3.2 𝐹 βŠ• 9 𝐹 βŠ• 0.42 % [E in GeV]

  • πœπ‘¦ = πœπ‘§ =

4.2 𝐹 βŠ• 0.6 mm [E in GeV] (1.5 mm @ 10 GeV)

NA48/2 𝑄𝐿 = 60 Β± 3 GeV/c 3-track vertex trigger Simultaneous 𝐿+ πΏβˆ’ beam πŽππŸ•πŸ‘π’π‹ 𝑄𝐿 = 74 Β± 2 GeV/c 𝐿𝑓2 trigger Alternate 𝐿+ πΏβˆ’ beam

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SLIDE 5

LNV in the 𝑳± β†’ 𝝆𝝂𝝂 decays

Nicolas Lurkin, HQL2016,24-05-2016 5

 Majorana Neutrinos

  • Asaka-Shaposhnikov model (πœ‰MSM) [PLB 620 (2005) 17]:

three sterile neutrinos Ni in the SM to explain Dark Matter (N1, 𝒫(keV)) + Baryon Asymmetry and low πœ‰ mass (N2,3 𝒫(100 MeV – few GeV))

  • Effective vertices with 𝑋±, π‘Ž and SM leptons with 𝑉 mixing matrix
  • Production of N2,3 in 𝐿± decays and N2,3 decay for 𝑛2,3 < 𝑛𝐿 βˆ’ π‘›πœˆ

𝐿± β†’ πœˆΒ±π‘‚, 𝑂 β†’ πœŒΒ±πœˆβˆ“

  • BR 𝐿± β†’ πœˆΒ±π‘‚ Γ— BR 𝑂 β†’ πœŒβˆ“πœˆΒ± ~ π‘‰πœˆ4

4

 Inflatons

  • Shaposhnikov-Tkachev model [PLB 639 (2006) 414]:

πœ‰MSM + real scalar field (inflaton πœ“) with scale-invariant couplings to explain universe homogeneity and isotropy on large scales/structures on smaller scales

  • πœ“-Higgs mixing (πœ„), πœ“-Higgs coupling β†’ universe reheating, πœπœ“ ~ 10βˆ’8 βˆ’ 10βˆ’12
  • Production in Kaon decays:

π‘›πœ“ < 354 MeV/𝑑2 and BR 𝐿± β†’ πœŒΒ±πœ“ = 1.3 Γ— 10βˆ’3

2 π‘žπœ“ 𝑁𝐿

πœ„2

For this result

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SLIDE 6

LNV: Same-Sign Muon Sample

Nicolas Lurkin, HQL2016,24-05-2016 6

 Blind analysis:

  • Selection based on simulation of

𝐿± β†’ πœŒβˆ“πœˆΒ±πœˆΒ± and 𝐿± β†’ 𝜌±𝜌+πœŒβˆ’ (background, similar topology)

  • 3-track vertex topology, 2 same-sign muons,

1 odd-sign pion, no missing momentum

  • First-order cancellation of systematic effects
  • Control region: π‘πœŒπœˆπœˆ < 480 MeV/𝑑2
  • Signal region: π‘πœŒπœˆπœˆ βˆ’ 𝑁𝐿 < 5 MeV/𝑑2

 Results:

  • Event in Signal Region: 𝑂𝑝𝑐𝑑 = 1
  • Expected background from MC:

𝑂exp = 1.163 Β± 0.867𝑑𝑒𝑏𝑒 Β± 0.021𝑓𝑦𝑒 Β± 0.116𝑑𝑧𝑑𝑒

  • From Rolke-Lopez statistical method:

𝐢𝑆 𝐿± β†’ πœŒβˆ“πœˆΒ±πœˆΒ± < 8.6 Γ— 10βˆ’11 @ 90% CL

M πœŒβˆ“πœˆΒ±πœˆΒ±

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SLIDE 7

 Results

  • Event in Signal Region:

3489 𝐿± β†’ 𝜌±𝜈+πœˆβˆ’ candidates

  • Background: 0.36 Β± 0.10 %
  • See [Phys. Lett. B697 (2011) 107] for

previous measurement of BR and FF

  • Search for resonances in π‘πœŒπœˆ and π‘πœˆπœˆ

invariant masses

  • step=0.5𝜏 𝑁𝑠𝑓𝑑 and window=Β±2𝜏 𝑁𝑠𝑓𝑑
  • Limit using Rolke-Lopez from 𝑂𝑝𝑐𝑑 and

π‘‚π‘“π‘¦π‘ž for each hypothesis

LNC: Opposite-Sign Muon Sample

7

 Selection

  • Similar to same-sign
  • 3-track vertex, 2 opposite-sign muons,

1 pion, no missing momentum

  • First-order cancellation of systematic effects
  • Signal region: π‘πœŒπœˆπœˆ βˆ’ 𝑁𝐿 < 8 MeV/𝑑2

M 𝜌±𝜈+πœˆβˆ’ M 𝜈+πœˆβˆ’ M πœŒΒ±πœˆβˆ“

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SLIDE 8

LNV and LNC: Resonances searches

Nicolas Lurkin, HQL2016,24-05-2016 8

 Search for 𝑳± β†’ π‚Β±π‘ΆπŸ“ π‘ΆπŸ“ β†’ π†βˆ“π‚Β± decays, 284 mass hypotheses

  • 2 possibilities for 𝑁 πœŒβˆ“πœˆΒ± , closest to 𝑁𝑠𝑓𝑑 chosen
  • Never exceeds +3𝜏: no signal observed and UL BR ~10βˆ’10 for 𝜐 < 100 ps

 Upper limit on 𝐂𝐒 𝑳± β†’ π‚Β±π‘ΆπŸ“ 𝐂𝐒 π‘ΆπŸ“ β†’ π†βˆ“π‚Β±

  • 𝑉𝑀 BR =

UL 𝑂𝑑𝑗𝑕 π‘‚πΏβˆ—π΅π‘‘π‘‘π‘“π‘žπ‘’π‘π‘œπ‘‘π‘“

 Statistical significance

  • 𝑨 =

π‘‚π‘π‘π‘‘βˆ’π‘‚π‘“π‘¦π‘ž 𝜏 𝑂𝑝𝑐𝑑 βŠ•πœ π‘‚π‘“π‘¦π‘ž

Nobs vs. 𝑁𝑠𝑓𝑑 𝑨 vs. 𝑁𝑠𝑓𝑑 UL(BR) vs. 𝑁𝑠𝑓𝑑

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SLIDE 9

LNV and LNC: Resonances searches

Nicolas Lurkin, HQL2016,24-05-2016 9

 Search for 𝑳± β†’ π‚Β±π‘ΆπŸ“ π‘ΆπŸ“ β†’ π†βˆ“π‚Β± decays, 284 mass hypotheses

  • 2 possibilities for 𝑁 πœŒβˆ“πœˆΒ± , closest to 𝑁𝑠𝑓𝑑 chosen
  • Never exceeds +3𝜏: no signal observed and UL BR ~10βˆ’10 for 𝜐 < 100 ps

 Search for 𝑳± β†’ π‚Β±π‘ΆπŸ“ π‘ΆπŸ“ β†’ π†Β±π‚βˆ“ decays, 280 mass hypotheses

  • Never exceeds +3𝜏: no signal observed and UL BR ~10βˆ’9 for 𝜐 < 100 ps

 Upper limit on 𝐂𝐒 𝑳± β†’ π‚Β±π‘ΆπŸ“ 𝐂𝐒 π‘ΆπŸ“ β†’ π†βˆ“π‚Β±

  • 𝑉𝑀 BR =

UL 𝑂𝑑𝑗𝑕 π‘‚πΏβˆ—π΅π‘‘π‘‘π‘“π‘žπ‘’π‘π‘œπ‘‘π‘“

 Statistical significance

  • 𝑨 =

π‘‚π‘π‘π‘‘βˆ’π‘‚π‘“π‘¦π‘ž 𝜏 𝑂𝑝𝑐𝑑 βŠ•πœ π‘‚π‘“π‘¦π‘ž

Nobs vs. 𝑁𝑠𝑓𝑑 𝑨 vs. 𝑁𝑠𝑓𝑑 UL(BR) vs. 𝑁𝑠𝑓𝑑

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SLIDE 10

LNV and LNC: Resonance searches

Nicolas Lurkin, HQL2016,24-05-2016 10

 Search for 𝑳± β†’ π‚Β±π‘ΆπŸ“ π‘ΆπŸ“ β†’ π†βˆ“π‚Β± decays, 284 mass hypotheses

  • 2 possibilities for 𝑁 πœŒβˆ“πœˆΒ± , closest to 𝑁𝑠𝑓𝑑 chosen
  • Never exceeds +3𝜏: no signal observed and UL BR ~10βˆ’10 for 𝜐 < 100 ps

 Search for 𝑳± β†’ π‚Β±π‘ΆπŸ“ π‘ΆπŸ“ β†’ π†Β±π‚βˆ“ decays, 280 mass hypotheses

  • Never exceeds +3𝜏: no signal observed and UL BR ~10βˆ’9 for 𝜐 < 100 ps

 Search for 𝑳± β†’ 𝝆±𝒀 𝒀 β†’ 𝝂+π‚βˆ’ decays, 267 mass hypotheses

  • Never exceeds +3𝜏: no signal observed and UL BR ~10βˆ’9 for 𝜐 < 100 ps

 Upper limit on 𝐂𝐒 𝑳± β†’ π‚Β±π‘ΆπŸ“ 𝐂𝐒 π‘ΆπŸ“ β†’ π†βˆ“π‚Β±

  • 𝑉𝑀 BR =

UL 𝑂𝑑𝑗𝑕 π‘‚πΏβˆ—π΅π‘‘π‘‘π‘“π‘žπ‘’π‘π‘œπ‘‘π‘“

 Statistical significance

  • 𝑨 =

π‘‚π‘π‘π‘‘βˆ’π‘‚π‘“π‘¦π‘ž 𝜏 𝑂𝑝𝑐𝑑 βŠ•πœ π‘‚π‘“π‘¦π‘ž

Nobs vs. 𝑁𝑠𝑓𝑑 𝑨 vs. 𝑁𝑠𝑓𝑑 UL(BR) vs. 𝑁𝑠𝑓𝑑

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SLIDE 11

𝛿 𝐡′ 𝜈 𝜈

Dark Photon Searches

Nicolas Lurkin, HQL2016,24-05-2016 11

 Simplest hidden sector model: Extra U(1) symmetry with gauge boson 𝑩′ [B.Holdom, Phys. Lett. B166 (1986) 196]  QED-like interactions with SM fermions

  • β„’ ~π‘•β€²π‘Ÿπ‘”

πœ”π‘”π›Ώπœˆπœ”π‘”π‘‰πœˆ

β€²

 Coupling constants and charges generated through kinetic mixing between QED and the new U(1) gauge bosons

  • ℒ𝑛𝑗𝑦 = βˆ’ πœ—

2 𝐺 πœˆπœ‰ 𝑅𝐹𝐸𝐺 𝑒𝑏𝑠𝑙 πœˆπœ‰

 Motivations:

  • Possible explanation for positron excess in cosmic rays (PAMELA,

FERMI, AMS-02) by dark matter annihilation

  • Possible solution to the muon g-2 anomaly

𝑓+ π‘“βˆ’ 𝐡′ 𝛿 𝐡′ 𝐡′ 𝐡′ πœ“ πœ“ π‘“βˆ’ π‘“βˆ’ 𝑓+ 𝑓+ ~TeV ~GeV

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SLIDE 12

DP: π†πŸ β†’ πœΉπ‘©β€² Decay

Nicolas Lurkin, HQL2016,24-05-2016 12

 Production Batell, Pospelov and Ritz, [PRD80 (2009) 095024]

  • BR 𝜌0 β†’ 𝛿𝐡′ = 2𝜁2 1 βˆ’

𝑛𝐡′

2

π‘›πœŒ0

2

3

BR 𝜌0 β†’ 𝛿𝛿

  • Mixing parameter 𝜁 and dark photon mass 𝑛𝐡′
  • Loss of sensitivity as 𝑛𝐡′ approaches the π‘›πœŒ0 threshold
  • For 𝜁2 > 10βˆ’7 and 𝑛𝐡′ > 10 MeV/𝑑2 mean free path is

negligible and prompt decay is assumed

  • Signature similar to 𝜌𝐸

𝜌𝐸

0 β†’ 𝛿𝑓+π‘“βˆ’; 𝜌0 β†’ 𝛿𝐡′

↳ 𝑓+π‘“βˆ’

Valid for 𝜁2 β‰ͺ 1

 Decay Batell, Pospelov and Ritz, [PRD79 (2009) 115008]

  • Accessible in 𝜌0 decay,

assuming only into SM fermions Ξ“

𝐡′ β‰ˆ Ξ“ 𝐡′ β†’ 𝑓+π‘“βˆ’

β‰ˆ π›½πœ2𝑛𝐡′/3

π’π†πŸ πŸ‘π’π‚ π’π†πŸ 𝑛𝐡′ > 2π‘›πœŒ0: hadronic decay contribution Assuming 𝜁2 = 10βˆ’4 𝑓+π‘“βˆ’ 𝜈+πœˆβˆ’ hadrons 𝑩′ decay width into SM fermions 𝑩′ decay BRs

BR 𝜌0 β†’ 𝛿𝐡′ vs. 𝑛𝐡′

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SLIDE 13

DP: NA48/2 Data Sample

Nicolas Lurkin, HQL2016,24-05-2016 13

 NA48/2 data: ~πŸ‘ Γ— 𝟐𝟏𝟐𝟐 𝑳± decays in the fiducial region  𝝆/𝝂/𝒇 separation using 𝑭/𝒒  Selection for 𝑳± β†’ 𝝆±𝝆𝑬

𝟏

  • Three-track vertex topology
  • π‘›πœŒπ›Ώπ‘“π‘“π‘“ βˆ’ 𝑛𝐿 < 20 MeV/𝑑2
  • 𝑛𝛿𝑓𝑓 βˆ’ π‘›πœŒ0 < 8 MeV/𝑑2
  • No missing momentum

 Selection for 𝑳± β†’ 𝝆𝑬

𝟏 𝝂±𝝃

  • 𝑛𝛿𝑓𝑓 βˆ’ π‘›πœŒ0 < 8 MeV/𝑑2
  • No missing mass

 Sensitivity determined by irreducible π†πŸ Dalitz decay (1.2%)  Acceptance for both signature depending on 𝒏𝑩′ up to 4.5%

𝑛2𝜌 𝑛𝑓𝑓 𝑛miss

2

𝑛𝑓𝑓

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SLIDE 14

DP: Signal Search

Nicolas Lurkin, HQL2016,24-05-2016 14

 Scan for narrow peaks in 𝒇+π’‡βˆ’ invariant mass spectrum

  • πœπ‘›π‘“π‘“ = 0.011 Γ— 𝑛𝑓𝑓
  • Range: 9 MeV/𝑑2 ≀ 𝑛𝐡’ < 120 MeV/𝑑2
  • Variable DP mass step: β‰ˆ 0.5𝜏 𝑛𝐡′
  • mass-window: Β±1.5𝜏 𝑛𝐡′
  • Limits from 𝑂𝑝𝑐𝑑 and π‘‚π‘“π‘¦π‘ž for each of the 404 𝑛𝐡′ hypotheses

Local signal significance never exceeds 3𝜏:

  • no DP signal is observed.

Nobs, Nexp vs. 𝑛𝐡′ 𝑨 vs. 𝑛𝐡′ UL(BR) vs. 𝑛𝐡′

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SLIDE 15

DP: Final NA48/2 Result

Nicolas Lurkin, HQL2016,24-05-2016 15

 [Phys.Lett. B746 (2015) 178]

  • Improvement on the existing limits in the

𝑛𝐡’ range 9 βˆ’ 70 MeV/𝑑2

  • Most stringent limits are at low

𝑛𝐡’ (kinematic suppression is weak)

  • Sensitivity limited by the irreducible

𝜌𝐸

0 background, ULs are 2-3 orders of

magnitude above SES.

  • Upper limit on 𝜁2 scales as ∼ 1/𝑂𝐿

1 2:

modest improvement with larger samples

  • If DP couples to quarks and decays

mainly to SM fermions, it is ruled out as the explanation for the anomalous 𝑕 βˆ’ 2 𝜈

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SLIDE 16

π†πŸ TFF: Dalitz Decay

Nicolas Lurkin, HQL2016,24-05-2016 16

π†πŸ β†’ 𝒇+π’‡βˆ’πœΉ  Kinematic variables

  • 𝑦 =

π‘žπ‘“++π‘žπ‘“βˆ’ 2 π‘›πœŒ0

2

, 𝑧 =

2π‘žπœŒ0 β‹… π‘žπ‘“+βˆ’π‘žπ‘“βˆ’ π‘›πœŒ0

2

1βˆ’π‘¦

 Differential decay width

  • 1

Ξ“ 𝜌2𝛿 𝑒2Ξ“ 𝜌𝐸 𝑒𝑦𝑒𝑧

= 𝛽

4𝜌 1βˆ’π‘¦ 3 𝑦

1 + 𝑧2 + 𝑠2

𝑦

1 + πœ€ 𝑦, 𝑧 𝐺 𝑦

2

 Form factor varies slowly:

  • Approximation 𝐺 𝑦 β‰ˆ 1 + 𝑏𝑦

 Slope measured from Dalitz decays from 𝐿± β†’ 𝜌±𝜌𝐸

  • Expectation from VMD: 𝑏 β‰ˆ 0.03
  • Enters hadronic light-by-blight scattering contribution to 𝑕 βˆ’ 2 𝜈
  • A. Nyffeler [arXiv:1602.03398]
  • Model independent measurement: important test of the theory

models

Electromagnetic Transition Form factor Radiative corrections

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SLIDE 17

π†πŸ TFF: Radiative Corrections

Nicolas Lurkin, HQL2016,24-05-2016 17

 Corrections from NLO differential width encoded in 𝜺 π’š, 𝒛

  • Mikaelian and Smith

[Phys.Rev. D5 (1972) 1763]

  • Husek, Kampf and Novotny [Phys.Rev. D92 (2015) 5, 054027]

 Corrections of same magnitude as TFF  New generator with radiative correction and simulation of bremsstrahlung photon.

πœ€(𝑦, 𝑧)

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SLIDE 18

π†πŸ TFF: Measurement principle

Nicolas Lurkin, HQL2016,24-05-2016 18

 Select pure 𝜌𝐸

0 sample from

  • 3-track vertex topology
  • One photon candidate and max three well

reconstructed tracks

  • Identification by reconstructed kinematics

115 MeV/𝑑2 < 𝑁𝑓𝑓𝛿 < 145 MeV/𝑑2 465 MeV/𝑑2 < π‘πœŒ+𝜌0 < 510 MeV/𝑑2 Dalitz variable y < 1; 0.01 < 𝑦 < 1

  • Reconstructed Kaon compatible with beam

properties and offline L2 and L3 trigger conditions

 Build 𝑦 Dalitz distribution for data and MC (equal population bins)  For each TFF slope value hypothesis, reweight simulated events (𝑏𝑑𝑗𝑛 = 0.032) π‘₯ 𝑏 = 1 + 𝑏𝑦𝑒𝑠𝑣𝑓 2 1 + 𝑏𝑑𝑗𝑛𝑦𝑒𝑠𝑣𝑓 2  Minimise πœ“2 𝑏 of Data/Simulation wrt. 𝑏

𝑁𝑓𝑓𝛿 𝑁2𝜌

slide-19
SLIDE 19

Uncertainties Source πœΊπ’ƒ Γ— πŸπŸβˆ’πŸ‘ Statistical – Data 0.49 Statistical – MC 0.20 Beam momentum spectrum simulation 0.30 Spectrometer momentum scale 0.15 Spectrometer resolution 0.05 LKr non-linearity and energy scale 0.04 Particle mis-ID 0.08 Accidental background 0.08 Neglected 𝜌𝐸

0 sources in MC

0.01

π†πŸ TFF: Preliminary Result

Nicolas Lurkin, HQL2016,24-05-2016 19

𝑏 = 3.70 Β± 0.53𝑑𝑒𝑏𝑒 Β± 0.36𝑑𝑧𝑑𝑒 Γ— 10βˆ’2 = 3.70 Β± 0.64 Γ— 10βˆ’2 (πœ“2/n.d.f: 52.5/49, p-value: 0.34)

x

 Data sample

  • Kaon decays: ~2 Γ— 1010
  • Fully reconstructed 𝜌𝐸

0 events in the

signal region (𝑦 > 0.01): 1.05 Γ— 106  Fit result illustration

  • Data / MC(a=0)

ratio

  • 20 equal population

bins

  • Points in bin

barycenters

Preliminary

𝑦

slide-20
SLIDE 20

π†πŸ TFF: World Data

Nicolas Lurkin, HQL2016,24-05-2016 20

 Theory expectations

  • K. Kampf et al., EPJ C46 (2006), 191.

Chiral perturbation theory: 𝑏 = 2.90 Β± 0.50 Γ— 10βˆ’2

  • M. Hoferichter et al., EPJ C74 (2014),

3180. Dispersion theory: 𝑏 = 3.07 Β± 0.06 Γ— 10βˆ’2

  • T. Husek et al., EPJ C75 (2015) 12, 586.

Two-hadron saturation (THS) model: 𝑏 = 2.92 Β± 0.04 Γ— 10βˆ’2

 CELLO measurement:

  • H. J. Behrend et al., Z. Phys. C49

(1991), 401. Extrapolation of space-like momentum region data fit to VMD model: 𝑏 = 3.26 Β± 0.26𝑑𝑒𝑏𝑒 Γ— 10βˆ’2

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SLIDE 21

Summary

Nicolas Lurkin, HQL2016,24-05-2016 21

 LNV decay @ NA48/2

  • 𝐢𝑆 𝐿± β†’ πœŒβˆ“πœˆΒ±πœˆΒ± < 8.6 Γ— 10βˆ’11 @ 90% CL

 Majorana Neutrinos and Inflaton @ NA48/2

  • 𝐿± β†’ πœˆΒ±π‘‚4 𝑂4 β†’ πœŒβˆ“πœˆΒ± : UL(BR) of the order of 10βˆ’10 for 𝜐 < 100 ps
  • 𝐿± β†’ πœˆΒ±π‘‚4 𝑂4 β†’ πœŒΒ±πœˆβˆ“ : UL(BR) of the order of 10βˆ’9 for 𝜐 < 100 ps
  • 𝐿± β†’ πœŒΒ±πœ“ πœ“ β†’ 𝜈+πœˆβˆ’

: UL(BR) of the order of 10βˆ’9 for 𝜐 < 100 ps

 Dark Photon searches @ NA48/2

  • Phys.Lett. B746 (2015) 178
  • Improved limits on DP mixing 𝜁2 in the mass range 9 βˆ’ 70 MeV/𝑑2
  • The whole region favoured by 𝑕 βˆ’ 2 𝜈 is excluded

 𝝆𝑬

𝟏 electromagnetic TFF slope @ πŽππŸ•πŸ‘π’π‹

  • 𝑏 = 3.70 Β± 0.53𝑑𝑒𝑏𝑒 Β± 0.36𝑑𝑧𝑑𝑒 Γ— 10βˆ’2
  • Preliminary model independent result
  • ~1 million fully reconstructed 𝜌𝐸

0 decays

  • Improves TFF precision in the time-like momentum region

First πŸ•π‰ observation of non zero slope in time-like region