Bernardo Adeva, USC Winter Meeting IMFP-2012 Benasque 30 May , 2012 1

1. Introduction2. B hh CP violation asymmetries 3. EW gauge boson production4. New b,c spectroscopy and exclusive dimuons5. Some B rare decays and Majorana neutrinos

LHCb RESULTS

54 institutions, 15 countries

3 Spanish universities among them :

Main LHCb highlights by Guy WilkinsonBSM with LHCb tomorrow

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The LHCb Apparatus

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The LHCb Trigger + Data acquisition

4

High efficieny (<90%)& good performance

2011 7.0 TeV 2011 7.0 TeV (1 fb(1 fb-1-1 recorded) recorded)

2010 (37 pb-1 recorded)

LHCb integrated luminosity

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CP-VIOLATIONIN B hh DECAYS

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CP violation , the challenge

Noninvariance of fundamental forces under the combined action of charge conjugation (C) and parity (P) transformations is well established in the K0 and B0 meson systems 1

Recent results from LHCb also provided evidence of CP violation in the decays of D0 meson: R. Aaij et al. (LHCb Collaboration) Phys. Rev. Lett. 108, 111602 (2012)

Yet LHCb has found CP violation in the only neutral heavy meson that remains, the Bs : R. Aaij et al. (LHCb Collaboration) Phys. Rev. Lett. 108, 201601 , published 16 May 2012

1 J. H. Christenson, J.W. Cronin, V. L. Fitch, and R. Turlay, Phys. Rev. Lett. 13, 138 (1964). B. Aubert et al. (BABAR Collaboration), Phys. Rev. Lett. 87, 091801 (2001). K. Abe et al. (Belle Collaboration), Phys. Rev. Lett. 87, 091802 (2001).

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CP violation , the challenge

All current experimental measurements of CP violation in the quark flavor sector are generally well described by the Kobayashi-Maskawa mechanism which is embedded in the framework of the Standard Model (SM) 1 .

However, it is believed that the size of CP violation in the SM is not sufficient to account for the asymmetry between matter and antimatter in the Universe 2 . Hence, additional sources of CP violation are being searched for as manifestations of physics beyond the SM.

1 N. Cabibbo, Phys. Rev. Lett. 10, 531 (1963). M. Kobayashi and T. Maskawa, Prog. Theor. Phys. 49, 652 (1973). 2 W.-S. Hou, Chin. J. Phys. (Taipei) 47, 134 (2009), http://psroc.phys.ntu.edu.tw/cjp/download.php?type=full&vol=47#=2&page=134.

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Charmless Two-Body Decays Bs,d →h+ h-

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Bs,d →h+ h- direct CP violation

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Direct CP-asymmetry in Bs → K+ π-

Phys. Rev. Lett. 108, 201601

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Annihilation Diagrams

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Effective Bs →K+ K- Lifetime

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Time Dependent B0 → K+ π- Fit

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Time Dependent CP Violation in B0 → π+π-

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Time Dependent CP Violation in Bs →K+ K-

t0 = 0.95 ps

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Summary on CPV asymmetries in Bs,d →h+ h-

(see Paula Alvarez’s talk tomorrow)

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Measurement of the Ds+ Ds

- production asymmetry in 7 TeV pp collisions

LHCb has determined the overall production asymmetry of Ds mesons

produced directly in pp collisions in the rapidity region 2.0 < < 4.5 and pT > 2 GeV :

0.10)%0.220.33()σ(D)σ(D

)σ(D)σ(DA

ss

ssP

Which is consistent with theoretical expectations 1 and , provides significant constraints on models of Ds

production, and it is a key input for CP violation measurements.

LHCb-PAPER-2012-009 May 4, 2012

M. Chaichian and A. Fridman Phys. Lett. B298 (1993) 218.E. Norrbin and R. Vogt arXiv:hep-ph/0003056 E. Norrbin and T. Sjostrand Eur. Phys. J. C17 (2000) 137.

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Ds+ Ds

- production asymmetry results

Subtle sources of production asymmetries :- only c can form a charmed baryon- non-independent fragmentation process- even interference with S-waves - are they reduced at central rapidities?

LHCb has reconstructed 771.031 Ds mesons with 1 fb-1 , using both magnet polarities,

and determined the +/ - detection asymmetries in (p,pT) to 1% .

Key idea: use the ratio of partial/full reconstructed D* S

D0 decays .

D0 K-++(-)3-momentum determined fromslow pion S

reconstruction

D*

RS

WS

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Ds+ Ds

- production asymmetry

Then use reconstructed Ds

K+ K- decays to measure theproduction asymmetry. Note no significant CP violation in decay is expected 1

being a Cabibbo favoured mode.

1 Y. Grossman, A. L. Kagan, and Y. Nir, Phys. Rev. D75 (2007) 036008 S. Bergmann and Y. Nir JHEP 09 (1999) 031.

Overall production asymmetry AP = (-0.33 0.22 (stat.) 0.10 (syst.)) %

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W,Z BOSON PRODUCTION WITH LHCb

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Electroweak boson production at LHCb

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EW boson production and PDFs

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EW boson production ratios

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W l signal

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Results Z production

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W production and W/Z ratios

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Results W+- asymmetry

Differential W+- asymmetry consistent with NNLO predictions

Lepton pseudorapidity

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Combined Electroweak Physics

b AND c SPECTROSCOPY

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B** spectroscopy

Mesons consisting of LIGHT / HEAVY quarks are an interesting laboratory to study QCD, just as the hydrogen atom was to understand QED.

The states with L=0 and spin-parity 0- (B) and 1- (B*) are well established. But precision spectroscopy of orbitally excited B states is still undone. Properties predicted by HQET (Heavy Quark Effective Field Theory).

,

,

100-200 MeV/c2 expected widths

Subject of LHCb study

Key idea : the spin of the heavy quark and the total spinJl of the light degrees of freedom are separately conserved.

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B** spectroscopy

Phys. Rev. Lett. 102 (2009) 102003.

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CDF 2009

First precision measurement by CDF II

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B** spectroscopy

How LHCb reconstructs B** states

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B** spectroscopy

B**0 B+- B**+ B0+

First observationFirst observationLHCb-CONF-2011-53LHCb preliminary 2011 data, 336 pb-1

Fit: signal 2 BW’s for B* 2 with fixed mass difference 45.8 MeV for M(B*)-M(B) (PDG)1 BW for B1. Fix yield ratio of two B* 2 transitions to be 0.930.18 [Phys. Rev. D64 (2001) 114004.]Fix B1/B2 width to be 0.90.2 [Phys. Rev. D53(1996) 231.] (B2

*) = 20.6 2.0 MeV/c2 Background: WS component + 2 broad gaussians representing B0* and B’1 states

B1 B2* B2

*+ B1+

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B** spectroscopy

BS2* BS1

(BS1) = 0.65 0.07 MeV/c2

(BS2*) = 1.85 0.13 MeV/c2

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B** spectroscopy

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Charmonium-like exotics

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Charmonium-like exotics

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Charmonium-like exotics

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Charmonium-like exotics

nb

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Charmonium-like exotics

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Charmonium-like exotics

Physical Review D 85,091103(R) (2012)

No confirmation of narrow J/ state X(4140) ; no evidence for X(4274)

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Bc and b-baryons

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Bc+ meson mass measurement

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Bc+ cross-section

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Bc+ J/ + - + mode

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Bc+ J/ + - + results

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Bc+ J/ + - + production

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Masses of b , b

LHCb-CONF-2011-060

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Masses of b , b

LHCb-CONF-2011-060

b[dsb] , b [ssb]

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Production of Λ0b Λ+

c- + -

Phys. Rev. D84 (2011) 092001. Phys. Rev. D84 (2011) 092001.

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Λ0b and b in D0pK- mode : preliminary

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Observation of excited Λb0 baryons

First observation by LHCb, significance of 4.9 and 10.1

Appreciable mismatch with respect to existing relativistic quarks models, reasonable agreement with large Nc (spin-averaged) approaches.arXiv:1205.3452v1 [hep-ex] 15 May 2012

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Measurements of b-hadron masses

LHCb has achieved world-best measurements of theB-meson and baryon masses in exclusive modes.The momentum is calibrated with J/ +- decays and verified to a relative precisionof 2 10-4 using other 2-body decays.

CDFCDFCDFCDF

BaBar

Mesons and baryons are colourlessobjects formed by quarks and gluons andbound by strong interaction. Masses can becompared with lattice QCD calculations.

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Summary on b,c spectroscopy at LHCb

B**sector LHCb has access to the poorly explored B**sector, and will improve the knowledge of their properties and decays X,Y,Z states First studies of X(3872) and X(4140) demonstrate potential of LHCb to explore the exotic meson sector. Future results on larger data sets. Bc studies at LHCb Mass and cross section measured using 2010 data First observation of Bc

+ J/ + - + (6.8 ) b baryon studies at LHCb Mass and lifetime of Λb

0 using 2010 data world best measurement by LHCb Masses of b , b measured using 2011 data world best measurement by LHCb Productions of Λb

0 measured with various decay modes first observation of Λ0

b D0pK- (6.8 ) and b D0pK- (2.6)

FORWARD DIMUONS

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Central Exclusive Dimuon Production No backward tracks, two forward tracks, no identified photon

c0,c1,

c2

J/ (2s)

pb925112474)4.5η(2σJ/

pb1571067)/cGeV2.5m,4.5η(2σ 2μμpppp

Consistent with 42 1 pb (QED)

Relative proportions c0 , c1, c2 very sensitive to models that can potentially explore gluon x 2 10 -6

0.03 0.20 σ/σ ψ(2s)J/

Previous result by CDF: PRL 102 (2009) 242001

SOME RARE b-DECAYS AND SEARCH FOR MAJORANA NEUTRINOS

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Search for B+ ++-

5.2 significance for B+ ++- signal yield 25.3-6.4 +6.7 events, 1 fb-1 integrated luminosity

Normalisation to B+ J/ K+

Branching ratio = (2.4 0.6 (stat.) 0.20 (syst.) ) 10-8

in good agreement with SM expectation 1 (1.96 0.21) 10-8

1 S. Hai-Zhen, L. Lin-Xia, and L. Gong-Ru, New Physics Effects on rare decays B+ ++- and B+ ++- in a top quark two-higgs-doublet model, Communications in Theoretical Physics 50 (2008) 696.

Best published limit : < 6.9 10-8 at 90% CL by Belle Collaboration Phys. Rev. D78 (2008) 011101

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Search for Bs (B0) + - + -

Non-resonant Bs 4µ decay highly suppressed in SM 1 , BR < 10-10. But may be enhanced by NP due to FCNC mediated by new particles decaying into µ+ µ- pairs 2

1 D. Melikhov and N. Nikitin, PRD 70, 114028 (2004) 2 S. Demodov and D. Gorbunov Flavor violating processes with sgoldstino pair production, arXiv:1112.5230.

Seven Bs J/ events observed in the resonant window (estimated BR (2.3 0.9) 10-8 ))

Using the full 1 fb-1 2011 data sample, in the non-resonant window after unblinding, one Bs µ+ µ- µ+ µ- event and no B0 µ+ µ- µ+ µ- evts are observed.

95% CL upper limits: B (Bs µ+ µ- µ+ µ- ) < 1.3 10-8

and B (B0 µ+ µ- µ+ µ- ) < 5.4 10-9

Expected backgrounds are :0.38-0.17 +0.23 (0.30-0.20 +0.22 ) for Bs (B0 )

LHCb-CONF-2012-010

Bs

B0 non-resonant window

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Search for Majorana neutrinos at LHCb

arXiv:1201.5600v2 [hep-ex] 23 Mar 2012b

du

c

¯

W-

W-

N

+

-

a)

b)

c)

Virtual Majorana neutrino

Resonant neutrino production

Also resonant production

“Searches for Majorana neutrinos in B- decays” (The LHCb Collaboration)

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Majorana neutrinos B- D+(*)- -

B- D+-- B- D*+--

No signal evidence, background from side bands

BR (B- D+--) < 6.9 10-7 95% CLBR (B- D*+--) < 2.4 10-6 95% CL

1 More stringent than previous Belle result , Phys. Rev. D84 (2011) 071106

1

a)

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Majorana neutrinos B- +- -

and B- Ds+- -

No signal seen above backgrounds: Neutrino on-shell masses (m4) have been searched for :

m4m4

b)

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Mass and lifetime acceptance for on-shell Majorana Neutrinos

B- +-- B- Ds+-- B- D0 +--

Neutrino mass acceptance

Our search has ignored thus far the possibility of a finite neutrino lifetime. All sensitivity is lost for lifetimes longer than 10-10s to 10-11s.

B- +--

Mass dependent upper limits on BR

(of course this does not apply for virtual Majoranas)

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b)

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Summary of Majorana neutrinos

Using B- +-- , neutrino mass dependent upper limits were established on the couplings |V4| of a heavy Majorana N to a muon and virtual W using matrix elements from [1]. A model dependent calculation [2] was used for B- D0 +-- , but the mode +-- is more sensitive. For the B- D+(*)- - , upper limits on the coupling cannot be extracted until there is theoretical calculation of hadronic form factor (as there is for 0 decay) .

[1] A. Atre, T. Han, S. Pascoli, and B. Zhang, JHEP 05 (2009) 030, arXiv:0901.3589. [2] D. Delepine, G. Lopez Castro, and N. Quintero, Phys. Rev. D84 (2011) 096011, arXiv:1108.6009.

b)

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Conclusion

LHCb has shown powerful performance as a forward detector in pp collisions at s = 7 TeV for precision b and c physics, with very good mass and proper time resolution, and excellent K/ separation : observation of asymmetries in forward production of EW bosons first observation of new resonances and decay modes great potential for exploring rare decays, including lepton flavor violation CP-violation has been observed for the first time in D0 and Bs mesons, and a wide range of measurements is forseen, with potential new physics discovery, both in CP-violation and very rare decays (see G. Wilkinson’s talk tomorrow)

BACKUP

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Lifetime distributions B0 and Bs

B0 → π+π-

Bs →K+ K-

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Charm spectroscopy

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Charm spectroscopy

Feed-down states DJ →D*(D*→D,D0)

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Charm spectroscopy

Feed-down states DsJ →D*K(D*→D,D0)

mmmmmmmmmmmmmmm

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Lifetime of Λb preliminary

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Mass of Λb

Phys. Lett. B 708 (2012) 241.

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Phys. Lett. B 708 (2012) 241.

Phys. Rev. D85 (2012) 032008.

Production of Λ0b : semi-leptonic decays