c c ➝ J/ y g

download c c  ➝ J/ y g

of 33

  • date post

    24-Feb-2016
  • Category

    Documents

  • view

    26
  • download

    0

Embed Size (px)

description

Quarkonium production in pp at LHC. y ’. CMS. c c ➝ J/ y g. LHCb. ϒ. CMS. c c1. c c2. c c0. 8 th Vienna Central European Seminar 25 – 27 Nov. 2011, Vienna, Austria. Hermine K. Wöhri, CERN. Quarkonium production puzzles: theory. - PowerPoint PPT Presentation

Transcript of c c ➝ J/ y g

PowerPoint Presentation

cc J/y g

y

cc1cc2cc0Hermine K. Whri, CERNCMSCMSLHCbQuarkonium production in pp at LHC8th Vienna Central European Seminar 25 27 Nov. 2011, Vienna, Austria2

CDF Run II data: prompt J/yPRL 99, 132001 (2007)NRQCD factorization: prompt J/y Braaten, Kniehl, Lee, PRD62, 094005 (2000)NLO colour-singlet: direct J/yHaberzettl, Lansberg, PRL100, 032006 (2008)

LOcolour singletNRQCD (colour singlet+ colour octet)pT [GeV/c]CDFIn 1995, CDF observed J/y and y direct production cross sections ~50 times larger than expectations from leading-order colour-singlet production

NRQCD (including colour-octet terms) described the measured cross section by freely adjusting long distance matrix elements

NLO CSM also able to describe cross sections but no theory able to reproduce the polarization data@1.96 TeVQuarkonium production puzzles: theory3Quarkonium polarization puzzles: Tevatron experimentsCDF Run ICDF Run IIHelicity frameCDF II vs CDF I not known what caused the change CDF vs D0 unlikely that the different rapidity ranges can justify the discrepancy... J/, pp s = 1.96 TeV|y| < 0.4 |y| < 0.6 PRL 85, 2886 (2000)PRL 99, 132001 (2007)01020-0.8-0.6-0.4-0.20.00.20.4pT [GeV/c]|y| < 1.8 |y| < 0.6 CDF Run IID0 Run II(1S), pp s = 1.96 TeVHelicity framePreliminaryPRL 101, 182004 (2008)__4Exotic quarkonium puzzles: CDF vs BelleCDF observed a structure in B+ (J/y f) K+decays on the basis of 115 12 B+ (in 6 fb-1)

M = 4143.4 +2.9-3.0 0.6 MeV and G = 15.3 +10.4-6.1 2.5 MeV

196 eventsCDFX(4140) J/y f with J/y mm and f K+K-BELLE could not confirm this state set an upper limit for sBR(X):

in contradiction to the CDF result

Does the X(4140) really exist??? [PRL 102 (2009) 242002]and arXiv:1101.60585Quarkonium spectroscopy challenges

CDF1P2PStates identified in analogy to the hydrogen atom: Y(1S), Y(2S), Y(3S), cb0,1,2(1P), cb0,1,2(2P), etc

Radially excited states, 1P, 2P, not well measured, but of equal importance for a proper understanding of QCD at work feed-down into nS states (30 40 %)[similar for charmonium]cb Y(1S) gwith Y(1S) mm6The LHC achievements seen with a critical eyeThe next slides give a guided tour through many quarkonium measurements presently available from the LHC experiments

Detailed comparisons probe their compatibility or disclose new puzzles, an important check given the past mutually contradictory resultsJ/y fraction from B decays7J/y mesons are copiously produced inB J/y X decays a background for studies of quarkonium production

Prompt and non-prompt J/y mesons areseparated through the lifetime dimension

[pseudo-proper decay length]lJ/y [mm]The beauty feed-down shows a strong pT dependence with saturation for pT > 50 GeV/c

The mid-rapidity data points seem to show a similar trend for s = 1.96 and 7 TeVbut the (very precise) CMS measurements sit systematically higher than those of CDF

J/y fraction from B decays vs. pT8ATLAS: arXiv:1104.3038CMS: arXiv:1111.1557looks goodFor a given pT, the most mid-rapidity CMS data show a rather different B-fractionthan the most forward LHCb dataJ/y fraction from B decays vs. pT and rapidity9CMS: arXiv:1111.1557LHCb: EPJ C71 (2011) 1645looks good

For a given pT, the most mid-rapidity CMS data show a rather different B-fractionthan the most forward LHCb dataJ/y fraction from B decays vs. pT and rapidity10CMS: arXiv:1111.1557LHCb: EPJ C71 (2011) 1645looks good

Prompt J/y pT distributions from LHCb11LHCb published very accurate measurements, in 5 rapidity bins, up to pT ~ 15 GeV

The shape of the pT distributionscan be reproduced by the function

LHCb: EPJ C71 (2011) 16455.2 pb-1

Prompt J/y pT distributions from LHCb and ATLAS12Also ATLAS presented very detailed measurements, extending to higher pT valuesLHCb published very accurate measurements, in 5 rapidity bins, up to pT ~ 15 GeV

The shape of the pT distributionscan be reproduced by the function

LHCb: EPJ C71 (2011) 1645ATLAS: arXiv:1104.3038ATLAS 2.27 pb-1ATLAS 2.3 pb-1LHCb 5.2 pb-1looks goodPrompt J/y pT shape vs. rapidity13 clearly increases from forward to central rapidity

b = 3.69Good agreement between the LHC experimentslooks goodPrompt J/y pT distributions from ATLAS, CMS and LHCbATLAS: arXiv:1104.338CMS: arXiv:1111.1557Thanks to the high luminosity at LHC the current prompt J/y spectra extend from pT = 0 already up to 70 GeV/c, spanning 6 orders of magnitudeThe ATLAS and recent CMS data agree extremely well over the full pT range14

Prompt J/y pT distributions from ATLAS, CMS and LHCbATLAS: arXiv:1104.338CMS: arXiv:1111.1557

15Thanks to the high luminosity at LHC the current prompt J/y spectra extend from pT = 0 already up to 70 GeV/c, spanning 6 orders of magnitudeThe ATLAS and recent CMS data agree extremely well over the full pT rangePrompt J/y pT distributions from ATLAS, CMS and LHCbATLAS: arXiv:1104.338CMS: arXiv:1111.1557

16Thanks to the high luminosity at LHC the current prompt J/y spectra extend from pT = 0 already up to 70 GeV/c, spanning 6 orders of magnitudeThe ATLAS and recent CMS data agree extremely well over the full pT rangePrompt J/y pT distributions from ATLAS, CMS and LHCbLHCb: EPJ C71 (2011) 1645ATLAS: arXiv:1104.338CMS: arXiv:1111.1557Thanks to the high luminosity at LHC the current prompt J/y spectra extend from pT = 0 already up to 70 GeV/c, spanning 6 orders of magnitudeThe ATLAS and recent CMS data agree extremely well over the full pT rangeGood agreement also with the forward ATLAS, CMS and LHCb data

17looks goodPrompt J/y pT distributions from ATLAS, CMS and LHCbThanks to the high luminosity at LHC the current prompt J/y spectra extend from pT = 0 already up to 70 GeV/c, spanning 6 orders of magnitudeThe ATLAS and recent CMS data agree extremely well over the full pT range Good agreement also with the forward ATLAS, CMS and LHCb data

LHCb: EPJ C71 (2011) 1645ATLAS: arXiv:1104.338CMS: arXiv:1111.155718looks goodInclusive y from LHCb

y mmy J/y ppLHCb measured the pT differential inclusive y cross section in two decay channels:

11k in y J/y pp

90k in y mmLHCb-CONF-2011-02619

Prompt y from CMSCMS measured the y inclusive, non-prompt and prompt pT differential cross-sectionPrompt production cross-section allows for direct comparison with theory (no feed-down)B-fraction as large for y as for J/y: for pT > 20 GeV/c, more than 50% come from B decays arXiv:1111.155720

21Prompt y to J/y sBR ratioThe y to J/y cross-section ratio increases with pTCDF measured a systematically higher ratio[PRD80 (2009) 031103 (R)][arXiv:1111.1557]It is puzzling to see that CDF measures a significantly higher ratio

The higher the collision energy the smaller should be the difference between the y and J/y cross sections

Is this a nave expectation?

22Prompt y to J/y sBR ratioThe y to J/y cross-section ratio increases with pTCDF measured a systematically higher ratio[PRD80 (2009) 031103 (R)][arXiv:1111.1557]It is puzzling to see that CDF measures a significantly higher ratio

Could it be that the CDF result is too high because of a luminosity bias (2s)?

The J/y and y data were collected in different runs; the luminosities do not cancelpuzzling

23Inclusive y to J/y sBR ratioDo we also see differences between CMS and LHCb?CMS: arXiv:1111.1557LHCb: EPJ C71 (2011) 1645 (J/y) LHCb-CONF-2011-026 (y)No significant difference between the CMS ratios and the most mid-rapidity LHCb resultDeserves a second look on the basis of the higher-statistics 2011 data

Note that these are inclusive ratios and thatthe B-fraction changes (slightly) with rapidity

To be redone with prompt ratios

(1S) pT distributions from CMS and LHCb24Also the bottomonium states are now available from more than one LHC experimentCMS: PRD 83 (2011) 112004LHCb: CMS-CONF-2011-016looks good(1S): pT2 vs. rapidityThe decreases at forward rapiditiesIt is much larger than for the J/y25b = 3.0

Quarkonia pT2 vs. rapidityWhile the is very different from J/y to Y, the average transverse kinetic energies are much closer and show similar trends versus rapidity26

(1S) rapidityGood compatibility between LHCb and CMS for the ds/dy 1S production cross section

27

looks good

fdir=0.5F. Maltoni

(1S) data-theory comparison

LHCbCMS28The NLO colour singlet model describes the Y(1S) pT differential cross sections, of CMS and of LHCb

The NRQCD model is equally successful !looks goodFirst measurement of the cc2 / cc1 cross-section ratio29

to be further improved with the higher-statistics 2011 data[LHCb-CONF-2011-020]

LHCb reported a first measurement of thecc2 / cc1 cross-section ratio

The measurement disagrees with NLO NRQCD

Even only using 2010 data, LHCb already has amore detailed measurement than CDF

LHCbAlso the cb already made a first appearance !CDF measured large feed-down contributions from the cb states to the Y(1S):cb(1P) Y(1S) = 27.1 6.9 4.4 % cb(2P) Y(1S) = 10.5 4.4 1.4 % for Y(1S) with |y| < 0.7 and pT > 8 GeV/c[PRL 84 (2000) 2094]M(cb(1P)) M(Y(1S)) = 0.44 GeVM(cb(2P)) M(Y(1S)) = 0.80 GeVcb(2P) ?cb(1P)30

CDF

Another look at cc productionCMS has a very good mass resolution (better than 10 MeV)thanks to a (very challenging) photon conversion measurement31cc0cc1cc2CMScc J/y gTomography of the CMS inner detectorswith photon conversions

Prospects for 2011 data analysis

All results shown in this presentation were based on the 2010 dataMuch larger event samples have been acquired in 2011

Good perspectives for many more measurements

More