Wow, gorgeous ladybirds - INFN

New experiment: LHCb
LHCb is the dedicated flavour physics experiment at the LHC
ATLAS & CMS search for the direct production of new states
while LHCb is designed to see their indirect effect on charm and
beauty decays via virtual production in loop diagrams:
Key topics for LHCb include:
- check whether CP violation is due to a single phase in the
quark mixing (CKM) matrix, as in the Standard Model
- Study rare decays: FCNC decays (e.g. Bs → µ+µ-) are strongly
suppressed in SM, may be enhanced by Supersymmetry, or
other new physics
July 5, 2012
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LHCb Collaboration
804 members
16 countries
55 institutes
Muon
detector
RICH
Calorimeters
July 5, 2012
Magnet
VELO
Tracker
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LHCb in Italia
Sedi INFN :
Bari
Bologna
Cagliari
LNF
Milano Bicocca
Ferrara
Roma I
Firenze
Genova
Roma II
Official Roles :
RICH Project leader: Clara Matteuzzi (Milano Bicocca)
Muon Project leader: Giovanni Passaleva (Firenze)
CP Working group convener: Marta Calvi (Milano Bicocca)
Key analysis working group co-coordinator:
Bs → μμ: G. Lanfranchi (LNF)
γ with loops: V. Vagnoni (Bologna)
Bd → K*μμ: A. Satta (Roma II)
Rare charm decays: W. Bonivento (Cagliari)
Jets and exotica: Clara Matteuzzi (Milano Bicocca)
July 5, 2012
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LHCb Site
July 5, 2012
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LHCb : Detector
The detector is a forward spectrometer operating in collider mode
bb cross section ~ 300 μb at √s = 7 TeV → ~ 100,000 bb pairs
produced/second (100x B factories). Charm production ~x20 higher!
10 – 300 mrad
p
p
[PYTHIA]
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Tracking Performances
Track reconstructed by combining information from VELO
TT and T stations
Momentum resolution:
∆p/p = 0.4 – 0.6 % (5–100 GeV/c)
Bs → J/ψ φ
Real data!
σ(mB) = 8 MeV/c2
cf
16 MeV/c2 [CMS DPS-2010-040]
22 MeV/c2 [ATLAS CONF-2011-050]
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Vertex Detection
VELO (Vertex Locator)
21 modules of r-φ silicon sensor disks
Retracted for safety during beam
injection
Beam
7 mm
r
z
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Vertex Detection
VELO (Vertex Locator)
21 modules of r-φ silicon sensor disks
Retracted for safety during beam
injection
Impact parameter resolution ~ 20 µm
Proper-time resolution: σt = 45 fs
cf CDF: σt = 87 fs
Beam
Prompt J/ψ
7 mm
7 mm
Bs → J/ψ φ
r
r
z
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LHCb : Detector
10 – 300 mrad
p
p
[PYTHIA]
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Particle Identification
Charged hadrons identified with two Ring-Imaging Cherenkov :
RICH1 aereogel +C4F10, cover 1<p<60 GeV/c, upstream magnet
RICH2 CF4, cover 15<p<100 GeV/c, downstream tracking station
εK →K > 90% for επ→K < 5%
Allows strong suppression of
combinatorial background in
hadronic decays e.g. φ → K+K−
Without RICH
With RICH
July 5, 2012
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Calorimeters and Muons
ECAL: Shashlik Pb-scintillator
σ(E)/E = 10% /√E ⊕ 1%
HCAL: Tile Fe-scintillator
allows triggering on hadronic final states
Βs → φ γ
ϒ→ µ+µ−
Mγγ (MeV/c2)
Muon system: 5 stations MWPCs/Fe
July 5, 2012
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Data Taking
Nominal LHCb luminosity = 2x1032 cm-2 s-1
Precision physics depending on vertex structure: easier in a
low-pileup environment
Continuous (automatic) adjustment of offset of colliding beams
allows luminosity to be levelled
Data taken with high efficiency > 90%
Offline data quality rejects < 1%
Detectors all with > 98% active
channels
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Trigger
Detector
Level-0 in hardware :
pT of e, µ, and hadron (thresholds ~ 1–3 GeV)
High Level Trigger :
all detectors read out into large CPU farm
(~1500 servers)
Output rate increased to 4.5 kHz to
include charm stream and to provide
data sample for analysis during shutdown
(event size ~ 60 kB)
Deferred triggering: fraction of events
written to local storage of CPUs and
4.5 kHz
processed during inter-fill gap
Storage
~10% increase in effective power
Data analysis: centralized “stripping” selection to produce
Micro-DST
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Physics Highlights : B -B & D -D Mixing
0
0
0
0
B mesons mixing well-established but very important in time
dependent asymmetries.
Fundamental ingredients :
- proper time resolutions
- flavor tagging
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Physics Highlights : B -B & D -D Mixing
0
B0
0
0
0
Bs0 → Ds+ π- decays
Bs0
D0 →KK
∆ms=17.72±0.04±0.03 ps-1
(world-best)
CDF : 17.77±0.10±0.07 ps-1
D0 → K-π+
with
July 5, 2012
Φ CPV phase
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Physics Highlights : B -B & D -D Mixing
0
B0
0
0
0
Bs0 → Ds+ π- decays
Bs0
D0 →KK
∆ms=17.72±0.04±0.03 ps-1
(world-best)
CDF : 17.77±0.10±0.07 ps-1
D0 → K-π+
with
July 5, 2012
Φ CPV phase
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CP Violation Measurements: Bs
CP violation is expected to be very small in Bs sector : excluded
in Δms Tevatron found some hints in ΔΓ=Γ − Γ =2∣Γ ∣cos φs
Golden mode : Bs → J/ΨΦ
L
H
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LHCb result consistent with Standard Model
First significant direct measurement of ∆Γs = 0.116 ± 0.018 ± 0.006 ps-1
φs also measured in a second mode: Bs → J/ψ f0
Combined result: φs = −0.002 ± 0.083 ± 0.027 rad
Still room for new physics:
increased precision required!
July 5, 2012
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CP Violation Measurements: Charm
CP violation < 10-3 in SM
Measure :
Exploit the D* decay D*± → D0π±
D0 →ππ and D0 → KK :
∆ACP = (−0.82 ± 0.21 ± 0.11)%
CDF ∆ACP = (−0.62 ± 0.21 ± 0.10)%
Combined :
∆ACP = (−0.67 ± 0.16 )% 3.8σ from no-CP
violation hypothesis
Before the LHCb result: “CP violation…
at the percent level signals new physics”
[Y. Grossman, arXiv:hep-ph/0609178] (and many others)
After:“We have shown that it is plausible that the SM accounts for
the measured value… Nevertheless, new physics could be at play”
July 5, 2012
[J.Brod et al, arXiv:1111.5000]
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Rare Decay: Bs → μμ Decay
B0s → μμ and B0d → μμ occur only via loop diagrams with a
branching ratio very well predicted:
BR(B0s → μμ) = (3.2 ± 0.2)10-9 BR(B0d → μμ) = (0.1 ± 0.01)10-9
Several beyond SM theories predict an enhancement of the BR
July 5, 2012
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New Italian Institutions
Members of CDF from Padova and from Pisa
Old CDF group in Padova
Donatella Lucchesi
Giovanni Busetto
Silvia Amerio
Pierluigi Totaro
Matteo Bauce
People will join LHCb in Padova:
Giovanni Busetto
70%
Donatella Lucchesi 80%
Silvia Amerio
70%
Pisa:
Giovanni Punzi, Franco Bedeschi, Michael Morello
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LHCb Padova
Service tasks
a) study current Same Side tagging algorithms and tune the
Monte Carlo simulation to be able to reproduce data;
b) set-up and maintain tools and procedures to tune flavor
tagging algorithms simulation on data;
c) definition of quantities necessary to include flavor tagging
algorithms in the framework for the skimming;
d) contribute to the off-line and production operations.
Analysis activities
The group would like to participate to Bs physics analysis where
the angle gamma can be determined, as one of the possible
measurements we can be involved.
July 5, 2012
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LHCb Padova Requests
Capitolo
kE
Missioni Interne
3.0
Missioni Estere
19.0
Consumo
3.0
Usati gli algoritmi standard di Gruppo 1 :
- 1kE MI per FTE + specifiche richieste
- 2 mu per FTE : LHCb weeks, analysis weeks, analysis meetings
Collaboration board (MU=3.8 kE)
- consumo= FTEx1.5kE
In sezione: 2mu calcolo
July 5, 2012
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LHCb Upgrade
Main LHCb limitation that currently prevents exploiting higher
luminosity is the hardware trigger: keeping output rate < 1 MHz
requires raising of thresholds → hadronic yields reach plateau:
- Propose to remove the hardware
trigger read out at 40 MHz
crossing rate.
- Flexible software trigger in CPU
farm → increase in yields by factor
10–20 at 1–2 × 1033 cm-2 s-1
- Requires replacing front-end electronics, planned for the long
shutdown in 2018
- Running for ~10 years will give 50 fb-1
July 5, 2012
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Detector Modification
Baseline detector modifications to allow 40 MHz readout
R&D on possible detector upgrades
July 5, 2012
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LHCb Upgrades in Italy
Nuove istituzioni Padova e Pisa ancora non si sono espresse sugli
upgrades. Siamo interessati al trigger come progetto comune.
July 5, 2012
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