LHCb Accomplishme

nts

S. Stone

1NSF, Nov. 5, 2013

& Future Physics

The LHCb Collaboration 667 Authors

62 Institutes 16 Countries

4 Groups from USA

Basking in light of 2008 Nobel Prize to Kobayshi & Maskawa, “for the discovery of the origin of the broken symmetry which predicts the existence of at least 3 families of quarks”

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The LHCb Detector Complementary to ATLAS & CMS

Built to exploit correlated bb production

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q B (rad)q B (rad)

Production Of B vs B

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Detector

f sensors

Rsensors

B-Vertex Measurement

Vertexing:• trigger on impact parameter• measurement of decay distance (time)

Ds

BsK

K

K

d~1cm

47 mm 144 mm

440 mmPrimary vertex

Decay time resolution = 40 fs

(s t) ~40 fs

Example: Bs → Ds K

Vertex Locator (Velo)Silicon strip detector with ~ 5 mm hit resolution 30 mm IP resolution

5NSF, Nov. 5, 2013

Momentum and Mass measurement

Momentum meas. + direction (VELO): Mass resolution for background suppression

6NSF, Nov.

5, 2013

btag

Bs K

K

p+, K

Ds

Primary vertex

Bs→ Ds KMass resolutions ~15 MeV

Bo

m(DsK)

o - +

NSF, Nov. 5, 2013

1 TeV Scale New Particles

Naturalness Higgs is most sensitive to physics of order M=125 GeV,

has been pushed to ~1 TeV due to absence of signals. Can be pushed higher. (Soni suggests 10 TeV for KK)

But corrections to Higgs mass go as M2, so can’t push M too high without getting into fine tuning problem

Need New Physics to cut off quantum corrections Suggested NP mechanisms: SUSY, Higgs

compositeness, and extra dimensions. Each predicts a rich spectrum of new states

7

Seeking New Physics HFP as a tool for NP discovery

While measurements of fundamental constants are fun, the main purpose of HFP is to find and/or define the properties of physics beyond the SM

HFP probes large mass scales via virtual quantum loops. An example, of the importance of such loops is the Lamb shift in atomic hydrogen

A small difference in

energy between 2S1/2 & 2P1 /2

that should be of equal energy

at lowest order

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Flavor as a High Mass Probe

Already excluded ranges if ci~1 , take ci = 1

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i

See: Isidori, Nir& Perez arXiv:1002.0900; Neubert EPS 2011 talk

Ways out1. New particles have

large masses >>1 TeV

2. New particles have degenerate masses

3. Mixing angles in new sector are small, same as in SM (MFV)

4. The above already implies strong constrains on NP

New physics ruled outfrom Li=0 to somewherein the blue boxes

NSF, Nov. 5, 2013

Limits on NP Higgs Yukawa’s (Harnik, Kopp & Zupan

arXiv:1209.1397)

10

A few b decay results

“The success of the LHCb experiment has so far been a nightmare for all flavour physicists…” Gauld, Goetz and Haisch arXiv:1310:1082

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Dms from Bs→Ds

+p-

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CPV in Bs→J/ yX

CP violation means, for example, that a B will have a different decay rate than a B

Can occur via interference

between mixing & decay

For f =J/y f or J/y f0

Small CPV expected, good place for NP to appear

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background

f (980)peak, nowuse larger range

0

fs from Bs→J/yp+p-

f0 Mode predicted

by Stone & Zhang,

found by LHCb In region between

arrows, measured

to be >97.7%

CP-odd @95% cl

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fs results

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Combined LHCb values: =0.661±0.04 ±0.006 G(ps-1).

=0.106 ±0.011±0.007 DG (ps-1), fs=0.01±0.07±0.01 (rad)Indications of large fs from CDF/D0 not confirmed

Bs→m+m- SM branching ratio is (3.2±0.2)x10-9 [Buras

arXiv:1012.1447], NP can make large contributions.

Many NP models possible, not just Super-Sym

16NSF, Nov. 5, 2013

Standard Model MSSM

~tan6b

NSF, Nov. 5, 2013

Evidence for Bs→m+m-

17

BDT

BsBo

B→h+h-

B→pmn

B→pmm

3/fb

CMS 25/fb

Fake D+

D+ Dfb

Prompt D+

LHCb

LHCb

D+→K-p+p+

Production fractions: B→DXmn

use equality of Gsl & known t’s

18NSF, Nov. 5, 2013

Ds→K-K+-p+

Ds

Also Do, Lb

Must know #Bs to measure B

Also B→Dh-

LHCb measures

fs/fd=0.259±0.015 Used by CMS & ATLAS Pt dependence now

evident, CMS/ATLAS

implications

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D-p+

D-K+ Ds-p+

Implications

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A sample of other results

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Electroweak Unique x-Q2

regions for structure function studies

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Central exclusive production

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J/y

Publications

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Syracuseauthored~20% ofLHCbpapers

LHCb Upgrade Can accumulate data ~x10 the rate in

hadronic channels, ~x5 in dimuon channels Relies on triggering at ~40 MHz without hard

wired cuts by using detached vertices Requires replacing all electronics except

calorimeter & muon, including rebuilding VELO, UT, TT & replacing RICH HPD’s

Allows us to extend range of mass probed for new physics by a significant factor

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Upgrade physics

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✓

✓= Syracuse analysis

✓

✓

✓

MIT

MIT

Importance of the UT Use VELO-UT in trigger to improve

throughput (see M. Williams talk) Reduces ghosts in

tracking

Essential for KS reconstruction for decays after the VELO

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Conclusions LHCb is now sensitive to potential New Physics

effects at high mass scales We are searching for and limiting New Physics,

especially in rare and CP violating b & c decays In addition there are important research

directions in other areas: light meson structure qq versus tetraquark, exotic mesons, central exclusive production, electroweak physics….

The upgrade will allow much more sensitive searches in a variety of areas

28NSF, Nov. 5, 2013

The End

29NSF, Nov. 5, 2013