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Дата изменения: Sat Sep 7 17:45:09 2013
Дата индексирования: Fri Feb 28 02:47:15 2014
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Quarkonia production at LHCb
Alexander Artamonov IHEP, Protvino, Russia On behalf of LHCb Collaboration

"16th Lomonosov conference" MSU, Moscow, Russia, 2228 August 2013

Physics motivation

EPJ C71 (2011) 1534

The study of properties of bound states of heavy quarks plays an important role in our understanding of QCD. J/and (2S) surplus problem (found by CDF about 20 years ago). Colorsinglet model failed to explain the data. Birth of colouroctet model. Renaissance of CSM. So CSM vs (or +) COM.

(2S)
PR D80 (2009) 031103

Ratio (c2)/(c1) is sensitive to CSM vs COM models. Prompt c give substantial feeddown to J/ production: crucial for polarization studies of J/ So far no model can simultaneously explain experimental measurements of quarkonia production and polarization (e.g. dependence on pT).
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LHCb measurements of heavy quarkonia

J/ crosssections at 7 TeV EPJ C71 (2011) 1645, arXiv: 1103.0423 J/ crosssections at 2.76 TeV JHEP 02 (2013) 041, arXiv:1212.1045

J/pair production at 7 TeV PL B707 (2012) 52, arXiv:1109.0963 J/+ open charm production at 7 TeV JHEP 06 (2012) 141, arXiv:1205.0975 J/ and (nS) production at 8 TeV JHEP 06 (2013) 064, arXiv:1304.6977

c production at 7 TeV (unconverted )
PL B714 (2012) 215, arXiv:1202.1080 PL B718 (2012) 431, arXiv:1204.1463

(2S) crosssections at 7 TeV EPJ C72 (2012) 2100, arXiv:1204.1258 (nS) crosssections at 7 TeV EPJ C72 (2012) 2025, arXiv:1202.6579 (nS) from b decay at 7 TeV
JHEP 11 (2012) 031, arXiv:1209.0282

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LHCb measurements of heavy quarkonia

J/ crosssections at 7 TeV EPJ C71 (2011) 1645, arXiv: 1103.0423 J/ crosssections at 2.76 TeV JHEP 02 (2013) 041, arXiv:1212.1045

J/pair production at 7 TeV PL B707 (2012) 52, arXiv:1109.0963 J/+ open charm production at 7 TeV JHEP 06 (2012) 141, arXiv:1205.0975 J/ and (nS) production at 8 TeV JHEP 06 (2013) 064, arXiv:1304.6977

c production at 7 TeV (unconverted )
PL B714 (2012) 215, arXiv:1202.1080 PL B718 (2012) 431, arXiv:1204.1463

(2S) crosssections at 7 TeV EPJ C72 (2012) 2100, arXiv:1204.1258 (nS) crosssections at 7 TeV EPJ C72 (2012) 2025, arXiv:1202.6579 (nS) from b decay at 7 TeV
JHEP 11 (2012) 031, arXiv:1209.0282

c production in pp at 7 TeV (converted )
arXiv:1307.4285 J/polarization in pp at 7 TeV arXiv:1307.6379 J/ production in pA and Ap collisions LHCbPAPER2013052 (New!)

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cJ production in pp @ s = 7 TeV
arXiv:1307.4285

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cJ production @ s = 7 TeV

arXiv:1307.4285

Previous measurement of cJ production by using noncoverted photons: = 36 pb1 Phys. Lett. B714 (2012) 215 & arXiv:1204.1462

c0

c1

Reconstructed in: c J/ where J/

c2

New measurement of cJ production by using converted photons: = 1 fb1 3< pT(J/) <20 GeV/c, 2 < y(J/) < 4.5

c1 c2 c0

Reconstructed in: c J/ where (J/ ) and ( e+e) Good mass resolution but low efficiency
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cJ production @ s = 7 TeV

arXiv:1307.4285

First evidence of c0 at hadron collider with statistical significance of 4.3 N(c0) = 705 163 Mass resolution: about 4 MeV/c

2

Ratio (c2)/(c1) is sensitive to CS vs CO models

c1

c1 c2
Ba ck gr ou nd su btr ac ted

c0

c2

c0

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cJ production @ s = 7 TeV
Ratio (c2)/(c1) and its comparison with theor y

arXiv:1307.4285

Ma, Wang, Chao (2010, 2011) Likhoded, Luchinsky, Poslavsky (2013)

These LHCb results obtained assuming the c mesons are produced unpolarized Good agreement with the model LO NRQCD. For the model of NLO NRQCD good agreement at high pT(J/)

4< pT(J/) < 20 GeV/c

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cJ production @ s = 7 TeV
Comparison of (c2)/(c1) obtained by dif ferent experiments

arXiv:1307.4285

The results from this analysis (converted photons) compatible with CMS and CDF results Better agreement achieved when c polarized with (m(c1), m(c2)) = (0,0)

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J/ polarization in pp @ s = 7 TeV
arXiv:1307.6379

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J/ polarization @ s = 7 TeV

arXiv:1307.6379

J/polarization: pp collisions @ s = 7 TeV, .37 fb1 (1st half of 2011) pT [2, 3, 4, 5, 7, 10, 15] GeV/c, y [2.0, 2.5, 3.0, 3.5, 4.0, 4.5], only prompt J/candidates Full angular analysis to determine the polarization parameters ( , , ) in HX & CS frames

S= /
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J/ polarization @ s = 7 TeV

arXiv:1307.6379

Lots of crosschecks have been done. BJ/ Kas a controlchannel to avoid any artificial polarization. The J/ polarization in BJ/ Kis fixed and known. Weights as function of muon pT and y obtained from the controlchannel BJ/ K

Muon cos in HX frame for J/ from BJ/ Kbefore final reweighting procedure.
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J/ polarization @ s = 7 TeV
Measurements of in bins of p
T

arXiv:1307.6379

helicity frame

CollinsSoper frame

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J/ polarization @ s = 7 TeV
Comparison of LHCb and ALICE results for

arXiv:1307.6379

Good agreement with ALICE measurements (due to large uncertainties in ALICE results) helicity frame

CollinsSoper frame

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J/ polarization @ s = 7 TeV
Comparison of LHCb results with theoretical models

arXiv:1307.6379

NPB 151 (2012) 222224 (Proc. Suppl.) PRL 110 (2013) 042002 PRL 108 (2012) 242004 NPB 151 (2012) 222224 (Proc. Suppl.)

Measured agrees with

neither theoretical prediction!

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J/ production in pA & Ap collisions (New!)
LHCbPAPER2013052

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J/ production in pA & Ap collisions
LHCbPAPER2013052

pA collision (2013) for ward production

p beam Ep = 4 TeV

.1 nb
Pb beam EN = 1.58 TeV

1

SNN = 5 TeV
rapidity coverage: 1.5 < y < 4.0 in pA 5.0 < y < 2.5 in Ap pT coverage: pT < 14 GeV/c Pb beam EN = 1.58 TeV

Ap collision (2013) backward production .5 nb1 p beam Ep = 4 TeV

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J/ production in pA & Ap collisions
Preliminar y

LHCbPAPER2013052

MC data sample is based on pp collision. Comparison of track multiplicity for for ward ( ), backward ( ) and MC data samples ( ). MC was reweighted to match the data. Dimuon mass spectra for pA (left) and Ap (right) collisions

·

·

·

Preliminar y

Preliminar y

pA
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Ap
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J/ production in pA & Ap collisions

LHCbPAPER2013052

Dif ferential production xsec's for prompt J/ and J/ from b (For the first time!)

Preliminar y

Preliminar y

pA
Preliminar y Preliminar y

Ap

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J/ production in pA & Ap collisions
Determination of nuclear modification factor

LHCbPAPER2013052

JHEP 06 (2013) 064

Since sNN = 5 TeV
Previous LHCb measurements of J/ production (at s = 2.76, 7 & 8 TeV) are rescaled to: (pT < 14 GeV) & (2.5 < y < 4.0)

Crosssections of J/from b and FONLL predictions in pp collisions for (pT < 14 GeV) & (2.0 < y < 4.5) JHEP 02 (2013) 041 [arXiv:1212.1045] J/@ 2.76 TeV EPJ C71 (2011) 1645 [arXiv:1103.0423] J/@ 7 TeV JHEP 06 (2013) 064 [arXiv:1304.6977] J/@ 8 TeV Lomonosov conference 2013

Powerlaw interpolation from the previous LHCb measurements to obtain prompt J/ (or J/ from b) crosssections in pp collisions at spp = 5 TeV

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J/ production in pA & Ap collisions

LHCbPAPER2013052

Nuclear modification factor for prompt J/ and J/ from b (For the first time!)

Suppression of J/ at large y is observed. This is less pronounced for J/ from b. It indicates that b hadrons are less af fected by cold nuclear matter ef fects. Within sizable uncertainties, the measurements agree with most theoretical predictions

Preliminar y

Preliminar y

predictions for prompt J/
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predictions for J/ from b
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J/ production in pA & Ap collisions
arXiv:1305.4569 JHEP 03 (2013) 122, arXiv:1212.0434 IJMP E22 (2013) 1330007, arXiv:1301.3395

LHCbPAPER2013052

For wardbackward production ratio for prompt J/ and J/ from b (For the first time!)

Within sizable uncertainties, the results agree with all theoretical predictions

Preliminary

Preliminar y

predictions for prompt J/
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predictions for J/ from b
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Summar y

By using converted photons, new measurements of ratio (c2)/(c1) has been determined as functions of pT(J/). The results for (c2)/(c1) are found to be in good agreement with LO NRQCD model. The full angular analysis for determining the polarization parameters ( , , ) of prompt J/produced in pp at s = 7 TeV has been performed. So far no theoretical model can explain these experimental results.

For the first time, dif f. production xsec's of prompt J/ and J/ from b are measured in pPb collisions at sNN = 5 TeV. For the first time nuclear modification factor and for ward backward production ratio are determined separately for prompt J/ and J/ from b in pPb collisions at sNN = 5 TeV.

Many new ongoing studies are in preparation. Stay tuned!
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Thank You

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Backup

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2<<5 4% of solid angle 40% of heavy quarks

The LHCb detector
is a for ward spectrometer designed for precision studies of CP violation and rare decays of b and chadrons
The LHCb Detector JINST 3 (2008) S08005

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J/ production in pA & Ap collisions

LHCbPAPER2013052

Comparison of MC and data samples. MC is based on pp collisions. Significant dif ference in track multiplicity distributions. MC was reweighted to match data.

Preliminar y

Preliminar y

Preliminar y

Preliminar y

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J/ production in pA & Ap collisions
Dimuon mass and pseudo proper time spectra

LHCbPAPER2013052

Preliminar y

Preliminar y

pA
Preliminar y Preliminar y

Ap

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