Some recent progresses in heavy hadron physics. Kazem Azizi. Oct 23-26, Second Iran & Turkey Joint Conference on LHC Physics

Transcription

1 Some recent progresses in heavy hadron physics Kazem Azizi School of Physics Doğuş University-Istanbul Oct 23-26, 2017 Second Iran & Turkey Joint Conference on LHC Physics 1

2 Outline v Introduction to the standard and exotic hadrons: situation in experiment v A useful theoretical tool: QCD sum rule v Recent developments in exotic sector: focusing on our recent works v Theoretical and experimental progresses on heavy standard hadrons and their excited resonances v Summary and conclusions 2

3 v Standard and exotic hadrons: situation in experiment Standard Hadrons Mesons: Baryons: 1-All light and heavy mesons predicted by theory have been discovered in the experiment; even their many excited states. 2- all light baryons and many of their resonances have also been observed. 3-all single-charmed baryons have been observed. Recently some Ω c resonances have also been observed by LHCb. 4- Except spin 3/2 Ω * b all single b-baryons have been discovered. 5- Only Ξ cc as doubly charmed baryons has been seen. 6- No doubly-bottom as well as triply charmed/bottom baryons have been discovered. 3

4 Both the quark model and QCD, do not exclude the non-conventional structures out of. Exotic states: tetraquarks, pentaquarks, hexaquarks, Hybrids, Glueballs,.. Their existence was theoretically predicted by Jaffe in 1976: The first exotic state, X(3872) was discovered in 2003 by Belle Collaboration. Tetraquarks: diquark-antidiquark, meson molecules X (3872): 2003 Belle D sj (2632): 2004 Fermilab SELEX Z(4430): 2007 Belle Y(4140) : 2009 Fermilab, 2012 CMS, 2013 D0, Belle did not found, LHCb confirmed Zc(3900): 2013 BESIII, Belle Z(4430):2014 LHCb X(5568): February 2016 D0, LHCb and CMS did not found. X(4274), X(4500) and X(4700): June 2016 LHCb For a history on theoretical studies see for instance: S. S. Agaev, K. Azizi, H. Sundu, Phys.Rev. D93 (2016) no.7, ; Phys.Rev. D93 (2016) no.11,

5 Pentaquarks: 4 quark-1 antiquark Baryon-Meson Molecule All experimental searches on pentaquarks were ended up in null results up to 2015: K. Azizi, Y. Sarac, H. Sundu, Phys. Rev. D 95 (2017) no.9, LHCb Pentaquarks, 2015:P c (4380) and P c (4450) in J/Ψ P invariant mass 5

6 R. Aaij et al. (LHCb Collaboration), Phys. Rev. Lett. 115, (2015) 6

7 Di-baryons: six quark states, baryon molecules 2014: WASA Synchrotron (COSY) Collaboration-Jülich, Germany... More investigations are needed. 7

8 Hybrids: quark-antiquark, Gluon Candidates (seen by different collaborations) : π 1 (1400 ), π 1 (1600), π(1800), η 2 (1870),. Glueballs (gluonium, gluon-ball): made of only gluons Candidates (seen by different collaborations) : f 0 (500), f 0 (980), f 0 (13800), f 0 (1500), f 0 (1710), X(3020),... Possible light and heavy Hybrids and Glueballs need more theoretical and Experimental investigations. 8

9 v A useful theoretical tool: QCD sum rule: ü In this method, hadrons are represented by their interpolating quark currents. ü The main object in this approach is the so called correlation function expressed in terms of these interpolating currents. 9

10 In this version, the OPE is done in terms of distribution amplitudes of the on-shell particles with different twists. This can be used in all electromagnetic, weak and strong decays. These correlation functions are calculated in two different ways: ü Phenomenological or hadronic side: in terms of hadronic parameters ü QCD or OPE side: in terms of QCD degrees of freedom The QCD sum rules for physical observables: Hadronic side is linked to OPE side by the help of a dispersion relation A Borel transformation and continuum subtraction are are applied to suppress the contributions of the higher states and continuum. 10

11 v Recent developments in exotic sector: focusing on our recent works Despite a lot of theoretical and experimental studies on exotic states their structure and quark organizations remain unclear. Zc(3900): 2013 BESIII, Belle Its mass and width was available from the experiment 11

12 12

13 Main input to analyze its strong, weak and electromagnetic decays 13

14 To calculate its width we consider its dominant decays 14

15 Belle Data BESIII Data Comparision of the theoretical results on both the mass and width with the experimental data results in: Z c (3900) can be considered as a hidden charm axial vector tetraquark 15

16 Fermilab: February 25, 2016 DZero discovers a new particle consistent with a tetraquark: X(5568) (with 5.1 standard deviation significance) Only particle made of four different quark flavors Tetraquark: diquark-antidiquark Meson molecule: B &K J PC =

17 First version of D0 Paper: arxiv: v1 LHCb (5-6 months later): No significant excess is found. arxiv: , Phys. Rev. Lett. 117, (2016) Later: very similar conclusions were drawn by CMS The CMS Collaboration, CMS PAS BPH

18 Final version of D0 Paper: arxiv: v5 Phys. Rev. Lett. 117, (2016) Further experimental analyses are needed 18

19 In theoretical side, however, a close and compress competition was started after D0 announcement on 25 February

20 We adopted Results: For decay constant we get 20

21 Its width in the same picture 21

22 Molecule Picture Results Both exceed the experimental data 22

23 Axial-vector tetraquark Results The mass exceeds and the width remains under the corresponding exp. data. Final interpretation: if exits X(5568) is most probably a scalar tetraquark. 23

24 We predicted the mass and width of charmed partner of X(5568). Experiments may search for them: 24

25 For width There are a lot of tetraquarks predicted via different theories, which may be searched for them in the future experiment. 25

26 LHCb Pentaquarks, 2015 We consider them as meson-baryon molecul admixture of 26

27 Exp. data Our work on their width is in progress 27

28 arxiv: [hep-ph] 28

29 v Theoretical and experimental progresses on heavy standard hadrons and their excited resonances New Ω c resonances: b-partners and other possible resonances 29

30 30

31 The LHCb could not fix their quantum numbers!!!!!!!! 31

32 After discovery: First interpretation via only mass: PDG: 32

33 A lot of interpretations have been made: including the pentaquark interpretations See: Agaev S. S., Azizi K. and Sundu H., Eur. Phys. J. C, 77 (2017)

34 The only interpretation via mass and width: 34

35 [1] LHCb Our final interpretation via mass & width Different than previous interp. 35

36 b-partners: S. S. Agaev, K. Azizi, H. Sundu, EPL 118 (2017) Exp: PDG 36

37 arxiv: [hep-ph], Accepted by Phys. Rev. D. 37

38 The obtained results may be useful for forthcoming experiments to explore bottom baryons and measure their spectroscopic and dynamical parameters. There may be other resonances in Ξ b(c), Λ b(c), Σ b(c) channels that need theoretical and experimental studies. 38

39 Ξ cc state: b-partners and other doubly/triply charmed-bottom baryons 39

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42 LHCb mass Was it a new discovery?????? 42

43 SELEX result (MeV) (2005-PDG): FermiLab Theoretical predictions: T. M. Aliev, K. Azizi, and M. Savcı, Nucl. Phys. A895, 59 (2012): GeV Theory says: it should a bit higher than the SELEX prediction. The LHCb measures: 43

44 We have predictions on the mass and other parameters of the possible doubly and triply charm/bottom baryons (with both the spin-1/2 and -3/2): T. M. Aliev, K. Azizi, M. Savci, Nucl.Phys. A895 (2012) 59 T. M. Aliev, K. Azizi M. Savci, J.Phys. G40 (2013) T. M. Aliev, K. Azizi, M. Savci, JHEP 1304 (2013) 042 T. M. Aliev, K. Azizi, M. Savci, J.Phys. G41 (2014) Experiments, especially the LHCb, may search for the in near future! 44

45 Summary and conclusions: -There have been good experimental and theoretical progresses on the properties of heavy hadrons both in standard and exotic sectors. -Despite a lot of theoretical and experimental studies, the nature and internal quark organizations of the exotic states remain unclear. -More theoretical and experimental investigations are needed to understand the newly discovered charm resonances by LHCb. -Experiments may search for the b-partners of the newly founded charm pentaquarks and other possible b-tetraquarks, Ω b resonances and doubly/triply heavy baryons. 45

46 Thank You 46