Mixing and Coherence in D Mesons Onur Albayrak (Carnegie Mellon - - PowerPoint PPT Presentation

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Mixing and Coherence in D Mesons Onur Albayrak (Carnegie Mellon - - PowerPoint PPT Presentation

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Mixing and Coherence in D Mesons Onur Albayrak (Carnegie Mellon University) on behalf of the BESIII Collaboration albayrak@phys.cmu.edu May 20 - Charm 2015 - Wayne State University 1 BEPC II Storage ring A -charm factory z 10 3 J /

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SLIDE 1

Mixing and Coherence in D Mesons

Onur Albayrak

(Carnegie Mellon University)

  • n behalf of the BESIII Collaboration

albayrak@phys.cmu.edu May 20 - Charm 2015 - Wayne State University

1

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SLIDE 2

BEPC II Storage ring

2

Institute of High Energy Physics (IHEP) campus Beijing, China

A

  • charm factory

10

  • 1

1 10 10 2 10 3 1 10

R

ω ρ φ ρ′

J /ψ

ψ(2S) Υ

√s [Ge V]

BESIII (direct) BESIII (ISR)

BESIII Spectroscopy |

  • W. Gradl

| 10

z

Onur Albayrak - CMU - BESIII Collaboration - Charm 2015

Beam energy: 1.0 - 2.3 GeV Energy spread: 5x10-4 Lpeak: 0.7x1033/cm2s

slide-3
SLIDE 3

Beijing Electron Spectrometer

3

BESIII Detector

BESIII data sets

104 energy points between 3.85 and 4.59 20 energy points between 2.0 and 3.1 GeV (ongoing) Direct production of 1 states studied with world's largest scan dataset

BESIII Spectroscopy |

  • W. Gradl

| 12

BESIII data sets

104 energy points between 3.85 and 4.59 20 energy points between 2.0 and 3.1 GeV (ongoing) Direct production of 1 states studied with world's largest scan dataset

BESIII Spectroscopy |

  • W. Gradl

| 12

Onur Albayrak - CMU - BESIII Collaboration - Charm 2015

1300 600

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SLIDE 4

Outline

  • D Tagging
  • Measurement of yCP in D0-D0 oscillation
  • GGSZ Analysis of D0→K0π+π-

̅

Onur Albayrak - CMU - BESIII Collaboration - Charm 2015

4

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SLIDE 5

Onur Albayrak - CMU - BESIII Collaboration - Charm 2015

5

D Tagging

+

e

  • e

(3770) ψ

1

D

+

K

  • K

2

D

K ) µ e(

) µ e(

ν

MBC ≡

  • E2

beam/c4 − |⃗

pD|2/c2

≡

  • E ≡ E D − Ebeam

D Tagging is used for selecting events. Single Tag, Fully reconstruct one D decay Double Tag, when the partner D is also reconstructed. Single Tag (ST): Tag modes are reconstructed requiring a certain window for the ΔE variable.

Example fits

DD pairs are produced while running at 3.773 GeV ~93% the time

Double Tag (DT): Depending on the D decay that is being studied, MBC or some other variable will be used to calculate double tag yields.

Both analyses that I will be talking about use D Tagging. ̅ ̅

MBC distribution is fit to calculate tag yields.

slide-6
SLIDE 6

Outline

  • D Tagging
  • Measurement of yCP in D0-D0 oscillation
  • GGSZ Analysis of D0→K0π+π-

̅

Onur Albayrak - CMU - BESIII Collaboration - Charm 2015

6

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SLIDE 7

|DCP−⟩ ≡ |D0⟩ − |D0⟩ √

2

Measurement of yCP in D0-D0 oscillation

ers x = m/ Ŵ

and y = Ŵ/2Ŵ,

Oscillations in D0-D0 system are characterized by mass and the width differences between two mass eigenstates

as |D1,2⟩ = p|D0⟩ ± q|D0⟩, ers and

= arg q p

is a

⟩ = | ⟩ ±

φ = arg(q/p)

ention CP|D0⟩ = +

rewrite

yCP = 1 2

  • y cosφ
  • q

p

  • +
  • p

q

  • − x sinφ
  • q

p

  • −
  • p

q

  • .

allowing small indirect CPV in the absence of CPV yCP reduces to y with |q/p| = 1 and 𝜚 = 0

Onur Albayrak - CMU - BESIII Collaboration - Charm 2015

At BESIII we are capable of producing D0D0 pairs at threshold with a definite C =−1 state. D mesons will have opposite CP . Semileptonic decays of D0 are used for probing the mixing parameter.

7

alue: ŴCP± = Ŵ(1 ± yCP).

is BDCP±→l ≈ BD→l(1 ∓ yCP),

Branching fraction of a semileptonic decay becomes:

yCP ≈ 1 4

BDCP−→l

BDCP+→l

− BDCP+→l

BDCP−→l

  • r opposite

use D0D0 Semileptonic CP eigenstate ̅ ̅

BDCP∓→l = NCP±;l

NCP±

· εCP±

εCP±;l

,

̅

̅

slide-8
SLIDE 8

Onur Albayrak - CMU - BESIII Collaboration - Charm 2015

8

Measurement of yCP in D0-D0 oscillation

+

e

  • e

(3770) ψ

1

D

+

K

  • K

2

D

K ) µ e(

) µ e(

ν

CP+ CP− Semileptonic K +K −, π+π−, K 0

Sπ 0π 0

K 0

Sπ 0, K 0 Sω, K 0 Sη

K ∓e±ν, K ∓µ±ν

Decays used in the analysis

Umiss ≡ Emiss − c|⃗ pmiss|,

Emiss ≡ Ebeam − E K − El,

  • ≡

− − ⃗

pmiss ≡ −

  • ⃗

pK + ⃗ pl + ˆ pST

  • E2

beam/c2 − c2m2 D

  • Single Tag (ST):

CP tag modes are reconstructed as single tags. Double Tag (DT): After reconstructing the CP tag, semileptonic decay of the pair D meson is reconstructed The Umiss distribution is fit to calculate the DT yields.

Example fits background

main Kππ 0

Quite clean after the analysis requirements, Umiss provides better resolution compared to M2miss

̅

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SLIDE 9

Onur Albayrak - CMU - BESIII Collaboration - Charm 2015

9

Measurement of yCP in D0-D0 oscillation - Results

Branching ratios of Ke𝜉 and K𝜈𝜉 are summed to calculate 𝓒CP±→ℓ Results are then combined for different CP modes using the standard weighted least-square method, minimizing,

BDCP∓→l = NCP±;l

NCP±

· εCP±

εCP±;l

,

Yields are then used to calculate the branching ratio, with the efficiency measured using the MC sample

χ 2 =

  • α
  • ˜

BDCP±→l − Bα

DCP±→l

2 σ α

CP±

2

yCP = (−2.0 ±1.3(stat)±0.7(sys))%

Result:

  • 4 -3 -2 -1

1 2 3 4 5

yCP (%)

World average 0.866 ± 0.155 % BaBar 2012 0.720 ± 0.180 ± 0.124 % Belle 2012 1.110 ± 0.220 ± 0.110 % LHCb 2012 0.550 ± 0.630 ± 0.410 % Belle 2009 0.110 ± 0.610 ± 0.520 % CLEO 2002

  • 1.200 ± 2.500 ± 1.400 %

FOCUS 2000 3.420 ± 1.390 ± 0.740 % E791 1999 0.732 ± 2.890 ± 1.030 % HFAG-charm

CHARM 2012

Phys.Lett. B 744 (2015) 339-346 HFAG - arxiv:1412.7515

̅

slide-10
SLIDE 10

Outline

  • D Tagging
  • Measurement of yCP in D0-D0 oscillation
  • GGSZ Analysis of D0→K0π+π-

̅

Onur Albayrak - CMU - BESIII Collaboration - Charm 2015

10

slide-11
SLIDE 11

γ γ α α

d

m ∆

K

ε

K

ε

s

m ∆ &

d

m ∆

ub

V β sin 2

(excl. at CL > 0.95) < 0 β

  • sol. w/ cos 2
excluded at CL > 0.95

α β γ

ρ

  • 1.0
  • 0.5

0.0 0.5 1.0 1.5 2.0

η

  • 1.5
  • 1.0
  • 0.5

0.0 0.5 1.0 1.5

excluded area has CL > 0.95 FPCP 13

CKM

f i t t e r

̅

Onur Albayrak - CMU - BESIII Collaboration - Charm 2015

11

Strong Phase Difference b/w D0 and D0 →K0𝜌+𝜌−

Motivated by the quest to increase the precision

  • f the angle 𝛿 measurement in B− →DK− decay.

argVudVub

* /VcdVcb *

*Giri, Grossman, Soffer, Zupan (GGSZ)

  • Phys. Rev. D 68 (2003) 054018

Determine 𝛿 through the interference between b →c and b →u transitions when 𝐸0 and 𝐸0 both decay to the same final state f(D). BESIII can help reducing the systematics on this important measurement with providing more information on the D0 →K0𝜌+𝜌− decay. With the amount of data LHCb collecting, 𝛿 measurement soon will be systematically limited.

B− D0K− D0K− f(D)K−

̅

A ðB ! K ~ D0; ~ D0 ! K0

Sþðx; yÞÞ

/ fDðx; yÞ þ rBeif

Dðx; yÞ:

and B , between the color- Here, x m2

K0

Sþ, y m2

K0

S

~0 ð Þð

ference D Dðx; yÞ Dðy; xÞ, ð Þ

We will use the GGSZ* method to investigate the decay Final states are three body, self-conjugate modes eg: KsKK, Ks𝜌𝜌

  • Binning regions of Dalitz plot where δD is similar
  • Model independent, there is no incorrect binning.
  • Optimization for binning for increased sensitivity.

̅

slide-12
SLIDE 12

̅

Onur Albayrak - CMU - BESIII Collaboration - Charm 2015

12

Strong Phase Difference b/w D0 and D0 →K0𝜌+𝜌−

  • Ti : measured in flavor decays
  • rB : color suppression ~0.1
  • δB : strong phase of B
  • ci,si : weighted average of cos(ΔδD) and sin(ΔδD),

phase difference between Ds given by ΔδD. All but ci,si variables will be measured in B factories.

0.5 1 1.5 2 2.5 3 s12 0.5 1 1.5 2 2.5 3 s13

Dalitz Plot

The i

¯th bin

  • f symmetry

the ith the ith

ci = ci and si = -si

Γ±

i ≡

  • i

dΓ(B± → (K0

Sπ−π+)DK±)

( = Ti + r2

BTı ± 2rB

  • TiTı[cos(δB + γ)ci − sin(δB + γ)si]

(

𝛿/ϕ3 = 68+8.0 −8.5

°

α/ϕ2 = 85.4+4.0 −3.9

°

β/ϕ1 = 21.38+0.79 −0.77

°

  • 𝛿
  • 𝛿
  • 78.4+10.8

−11.6 𝑡𝑢𝑏𝑢 ± 3.6(𝑡𝑧𝑡𝑢) ± 8.9(𝑁𝑝𝑒𝑓𝑚) Belle Model-Independent Dalitz 77.3+15.1 −14.9 𝑡𝑢𝑏𝑢 ± 4.2(𝑡𝑧𝑡𝑢) ± 4.3(𝑑𝑗/𝑡𝑗)

Currently statistically limited,

𝛿 Belle model independent 𝛿 measurement

ci,si error dominates

  • Phys. Rev. D 85, 112014 (2012)
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SLIDE 13

̅

Onur Albayrak - CMU - BESIII Collaboration - Charm 2015

13

Strong Phase Difference b/w D0 and D0 →K0𝜌+𝜌−

ci,si can be measured using the Double Tags: D0 →Ks𝜌+𝜌− vs (KS/L𝜌+𝜌− or CP tags)

ci and si c’i and s’i

[Ks𝜌+𝜌− vs CP tags] [KL𝜌+𝜌− vs KS𝜌+𝜌−] [KS𝜌+𝜌− vs KS𝜌+𝜌−] [KL𝜌+𝜌− vs CP tags] Use both (ci ,si) and (c’i ,s’i) to further constrain the results (ci ,si) Babar optimized Binning Scheme 2008:

Optimized to increase sensitivity to 𝛿, and smooths the bins to account for the regions that are smaller than the detector resolution.

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SLIDE 14

̅

Onur Albayrak - CMU - BESIII Collaboration - Charm 2015

14

Strong Phase Difference b/w D0 and D0 →K0𝜌+𝜌−

c’s Previous Measurement

𝑡𝑗 𝑑𝑗 𝑡𝑗 𝑑𝑗 𝑑𝑗 𝑡𝑗 𝑑𝑗 𝑡𝑗

c’s Previous Measurement

𝑡𝑗 𝑑𝑗 𝑡𝑗 𝑑𝑗 𝑑𝑗 𝑡𝑗 𝑑𝑗 𝑡𝑗

c’s Previous Measurement

𝑡𝑗 𝑑𝑗 𝑡𝑗 𝑑𝑗 𝑑𝑗 𝑡𝑗

Bin

𝑑𝑗 𝑡𝑗

c’s Previous Measurement

𝑡𝑗 𝑑𝑗 𝑡𝑗 𝑑𝑗 𝑑𝑗 𝑡𝑗

Bin

𝑑𝑗 𝑡𝑗

BESIII Preliminary BESIII Preliminary BESIII Preliminary BESIII Preliminary BESIII CLEO-c Model Measured using the worlds largest ψ(3770) data sample taken at the threshold. Results consistent with the CLEO-c with superior statistical uncertainties. Contribution to the uncertainty in gamma of ±2.1° using optimal binning, compared to Belle’s current measurement of ±4.3° from CLEO-c’s results.

CLEO-c result: Phys. Rev. D 82, 112006

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SLIDE 15

Onur Albayrak - CMU - BESIII Collaboration - Charm 2015

15

Thank you! Summary and Outlook

  • ycp measurement online. Phys.Lett. B 744 (2015) 339-346
  • Finalizing the D0 →K0𝜌+𝜌− model independent measurement.
  • More quantum coherence papers are in the works.