First physics from LHCb and prospect for coming years on CP violation measurements CPV from B factories to Tevatron and LHCb � 1 Sept-2 Sept 2010, Sendai, Japan � � Tatsuya NAKADA � Laboratory for High Energy Physics (LPHE) Swiss Federal Institute of Technology Lausanne (EPFL) Lausanne, Switzerland �
LHC at CERN � Circumference of 27 km � CPV from B factories to Tevatron and LHCb, Sendai, Japan, 1-2.9.2010 � T. Nakada � 2 �
LHC at CERN � ������������ ����������� ���������� ������ Two general purpose experiments (ATLAS and CMS), one dedicated b-experiment (LHCb), and one dedicated heavy ion � experiment (ALICS) from the beginning. � CPV from B factories to Tevatron and LHCb, Sendai, Japan, 1-2.9.2010 � T. Nakada � 3 �
LHC running, LHCb collecting data � • November 2009, √ s = 900 GeV collisions took place � • Since March 2010, running at √ s = 7 TeV � – n p-bunch ≈ 10 11 � � � � already nominal value � � – β � = 3.5 m � � � � nominal 0.55 m for 10 34 cm � 2 s � 1 � � � � � � nominal = 2808 � – n bunch = 46 � � � – L = 1 × 10 31 cm � 2 s � 1 � � � nominal = 10 34 cm � 2 s � 1 � – Experiments >90% DAQ ef fi ciencies � – Current plan for this year n bunch = 46 steadily increased to 384 � L ≈ 10 31 cm � 2 s � 1 � ⇒ � 10 32 cm � 2 s � 1 ( ∼ 0.2 pb � 1 /10h fi ll ) � • 2011: ∫ L d t = 1 fb � 1 goal to be achieved by running with a slight improvement (~2 in the luminosity) by further decreasing β � and/or increasing the number of bunches. � CPV from B factories to Tevatron and LHCb, Sendai, Japan, 1-2.9.2010 � T. Nakada � 4 �
23 rd November 2009 � • First collisions took place at LHC � • 2009 run: ∫ L d t ≈ 7 μ b � 1 , at √ s = 900 GeV � 0 cross sections One of the fi rst event � K S to be published in PLB � CPV from B factories to Tevatron and LHCb, Sendai, Japan, 1-2.9.2010 � T. Nakada � 5 �
LHC running, LHCb collecting data � • November 2009, √ s = 900 GeV collisions took place � • Since March 2010, running at √ s = 7 TeV � – n p-bunch ≈ 10 11 � � � � already nominal value � � – β � = 3.5 m � � � � nominal 0.55 m for 10 34 cm � 2 s � 1 � � � � � � nominal = 2808 � – n bunch = 46 � � � – L = 1 × 10 31 cm � 2 s � 1 � � � nominal = 10 34 cm � 2 s � 1 � – Experiments >90% DAQ ef fi ciencies � – Current plan for this year n bunch = 46 steadily increased to 384 � L ≈ 10 31 cm � 2 s � 1 � ⇒ � 10 32 cm � 2 s � 1 ( ∼ 0.2 pb � 1 /10h fi ll ) � • 2011: ∫ L d t = 1 fb � 1 goal to be achieved by running with a slight improvement (~2 in the luminosity) by further decreasing β � and/or increasing the number of bunches. � CPV from B factories to Tevatron and LHCb, Sendai, Japan, 1-2.9.2010 � T. Nakada � 6 �
Impressive progress in L � Peak luminosity Integrated luminosity already ~10 31 cm � 2 s � 1 � already ~3 pb � 1 � CPV from B factories to Tevatron and LHCb, Sendai, Japan, 1-2.9.2010 � T. Nakada � 7 �
LHC running, LHCb collecting data � • November 2009, √ s = 900 GeV collisions took place � • Since March 2010, running at √ s = 7 TeV � – n p-bunch ≈ 10 11 � � � � already nominal value � � – β � = 3.5 m � � � � nominal 0.55 m for 10 34 cm � 2 s � 1 � � � � � � nominal = 2808 � – n bunch = 46 � � � – L = 1 × 10 31 cm � 2 s � 1 � � � nominal = 10 34 cm � 2 s � 1 � – Experiments >90% DAQ ef fi ciencies � – Current plan for this year n bunch = 46 steadily increased to 384 � L ≈ 10 31 cm � 2 s � 1 � ⇒ � 10 32 cm � 2 s � 1 ( ∼ 0.2 pb � 1 /10h fi ll ) � • 2011: ∫ L d t = 1 fb � 1 goal to be achieved by running with a slight improvement (~2 in the luminosity) by further decreasing β � and/or increasing the number of bunches. � CPV from B factories to Tevatron and LHCb, Sendai, Japan, 1-2.9.2010 � T. Nakada � 8 �
LHCb Detector � �������������� �������� ������������ ���������������� ������������� ������� ��������������� ������� ������� CPV from B factories to Tevatron and LHCb, Sendai, Japan, 1-2.9.2010 � T. Nakada � 9 �
Quick reminder for LHCb � LHCb is a forward spectrometer dedicated for fl avour physics � b � pp-c.m. system � b � θ � � b � b � Both b and b are in the spectrometer. � CPV from B factories to Tevatron and LHCb, Sendai, Japan, 1-2.9.2010 � T. Nakada � 10 �
Quick reminder for LHCb � Forward: p T threshold can be set low: → high b ef fi ciency � For triggering…. p > p min � muon: identi fi cation � hadron: energy resolution � p < p min � σ E / E ≈ √ 70%/ √ E � Fe � p > p min � CPV from B factories to Tevatron and LHCb, Sendai, Japan, 1-2.9.2010 � T. Nakada � 11 �
Quick reminder for LHCb � Forward: p T threshold can be set low: → high b ef fi ciency � For triggering…. p > p min � muon: identi fi cation � hadron: energy resolution � p < p min � σ E / E ≈ √ 70%/ √ E � Fe � p > p min � central detector � forward detector � p ≈ p L > p min � p ≈ p T > p min � p � p � p � p � CPV from B factories to Tevatron and LHCb, Sendai, Japan, 1-2.9.2010 � T. Nakada � 12 �
Quick reminder for LHCb � Can exploit low p T particles to trigger more b-hadron events � pT of B-hadron σ bb expected in pp collisions at � √ s = 14 TeV: � 500 μ b � ATLAS/CMS 10 2 5 × 10 11 bb pairs in 10 7 s with 100 μ b � LHCb L = 10 32 cm � 2 s � 1 � 230 μ b � 10 1 -2 0 2 4 6 eta of B-hadron CPV from B factories to Tevatron and LHCb, Sendai, Japan, 1-2.9.2010 � T. Nakada � 13 �
LHCb σ bb measurements � b detection from b � D 0 (K � π + ) μ � X � Inclusive D: � Clean D signal with hadron PID � CPV from B factories to Tevatron and LHCb, Sendai, Japan, 1-2.9.2010 � T. Nakada � 14 �
LHCb σ bb measurements � b detection from b � D 0 (K � π + ) μ � X � Inclusive D: � dominated by the prompt production � IP(D from b � D) > IP (prompt D) � CPV from B factories to Tevatron and LHCb, Sendai, Japan, 1-2.9.2010 � T. Nakada � 15 �
LHCb σ bb measurements � b detection from b � D 0 (K � π + ) μ � X � Adding μ with a right sign enhances D from b: � e.g. B � � D 0 ( � K � π + ) μ � X [B � � D 0 ( � K + π � ) μ � X only through DCSD] � d � s � μ � � π + � Κ + � u � u � ν� b � c � s � d � B � D 0 � K � � π � � u � u � u � u � × 0.22 2 � CPV from B factories to Tevatron and LHCb, Sendai, Japan, 1-2.9.2010 � T. Nakada � 16 �
LHCb σ bb measurements � b detection from b � D 0 (K � π + ) μ � X � Adding μ with a right sign enhances D from b: � e.g. B � � D 0 ( � K � π + ) μ � X [B � � D 0 ( � K + π � ) μ � X only through DCSD] � with right sign muons � with wrong sign muons � CPV from B factories to Tevatron and LHCb, Sendai, Japan, 1-2.9.2010 � T. Nakada � 17 �
LHCb σ bb measurements � b detection from b � D 0 (K � π + ) μ � X � ∫ L d t = 25 nb � 1 data � Theory � uncertainty � CPV from B factories to Tevatron and LHCb, Sendai, Japan, 1-2.9.2010 � T. Nakada � 18 �
LHCb σ bb measurements � b detection from b � J/ ψ X � Clean μ + μ � mass distribution � with ∫ L d t = 14 nb � 1 data � CPV from B factories to Tevatron and LHCb, Sendai, Japan, 1-2.9.2010 � T. Nakada � 19 �
LHCb σ bb measurements � b detection from b � J/ ψ X � proper time distribution of J/ ψ� prompt J/ ψ� J/ ψ from b � CPV from B factories to Tevatron and LHCb, Sendai, Japan, 1-2.9.2010 � T. Nakada � 20 �
LHCb σ bb measurements � b detection from b � J/ ψ X � proper time distribution of J/ ψ� prompt J/ ψ� with detector resolution � J/ ψ from b � negative proper time important for studying resolution � CPV from B factories to Tevatron and LHCb, Sendai, Japan, 1-2.9.2010 � T. Nakada � 21 �
LHCb σ bb measurements � b detection from b � J/ ψ X � proper time distribution of J/ ψ� combinatorial background � prompt J/ ψ� with detector with resolution � prompt tracks and b tracks � J/ ψ from b � negative proper time important for studying resolution � CPV from B factories to Tevatron and LHCb, Sendai, Japan, 1-2.9.2010 � T. Nakada � 22 �
LHCb σ bb measurements � b detection from b � J/ ψ X � Proper time distribution with ∫ L d t = 14 nb � 1 data � side band � J / ψ with a long � proper time � due to b-hadron � decays � CPV from B factories to Tevatron and LHCb, Sendai, Japan, 1-2.9.2010 � T. Nakada � 23 �
LHCb σ bb measurements � LHCb σ bb from b � D 0 μ X and � J/ ψ X � 2< η <6 � σ bb in 4 π = 292 ± 15 ± 43 μ b (with LEP B u /B d /B s / Λ b ) � � � agree with the Pythia used for the performance studies � CPV from B factories to Tevatron and LHCb, Sendai, Japan, 1-2.9.2010 � T. Nakada � 24 �
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