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HSQCD 2004 DGLAP GLR DPP BFKL Alan Martin (Durham) Repino, St. Petersburg 18-22 May, 2004.

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Presentation on theme: "HSQCD 2004 DGLAP GLR DPP BFKL Alan Martin (Durham) Repino, St. Petersburg 18-22 May, 2004."— Presentation transcript:

1 HSQCD 2004 DGLAP GLR DPP BFKL Alan Martin (Durham) Repino, St. Petersburg May, 2004

2 Klempt not a glueball Glueballs, hybrids, pentaquarks

3 Klempt

4 Pentaquarks Several expts see an exotic B=1, S=1 baryon resonance in K + n or K 0 p channel  s (1530) with narrow width  <10 MeV

5 The chiral soliton model (  SM) predicted  s (1530) with  <15 MeV, J P =(1/2) + in a 10 of SU(3) f Praszalowicz(1987), Diakonov,Petrov,Polyakov(1997)  s (1530) N     NA49 see  (1860) which is not seen by ZEUS & WA89 seen by many expts in K + n, K 0 p

6 Popov

7 HERMES but is  s (1530) seen by H1 ?? Hyarapetian

8 1.5 MeV now expected from  SM --- Petrov Kubantsev


10 Petrov Bag model fails for  + (uudds) Need new degree of freedom: diquark ? CQM Jaffe-Wilczek (ud) 2 s Karliner-Lipkin (ud)(uds) …..but needs diquark in P-wave, many problems, always predicts too heavy  + e.g. Narodetskii  is lightest degree of freedom  SM

11  s (1530) N   Polyakov is the N*(1710) in the 10 ? considers mixing with octet  p  p* /  n  n* ~ 0 by U-spin  ~ MeV  N PWA: N* could be P11(1680 or 1730)  N 2 MeV  5 MeV  N 3 MeV Petrov considers mixing with the Roper octet

12 Klempt

13 1577 ?  SM predicts 27 with I=1 KN multiplet -- but K + p partner not seen

14 H1 see  c which is not seen by ZEUS ? Buschhorn bb prod: latest data and theory in satisfactory agreement

15 Hadron spectroscopy is on the boil. Changes almost daily. Very exciting and experimentally confusing.

16 low x Rostovsev

17 Fixed target DIS ep, ed, N; D-Yan, W asym, Tevatron jets HERA ep  global DGLAP parton analyses CTEQ, MRST  analyses to selected data sets Botje, Alekhin, ZEUS, H1… Expect small x processes to be driven by the gluon. Surprise  at v.low scales appear to be dominated by by singlet sea quarks  valence-like or -ve gluon ! Sea quarks & gluons not (perturbatively) connected.

18 x

19 1993 (Lum=20 nb -1 ) Now F 2 versus x

20 Regge confinement BFKL DGLAP ln Q 2 ln 1/x saturation absorptive corr. HERA

21 HERA has opened up the small x domain how large is the DGLAP domain ? are BFKL (log 1/x) effects evident ? is there any evidence of absorptive corrections, or even parton saturation ? HERA observes diffractive DIS (at ~10% of DIS). What role does it play ? what would we like HERA to measure now ?

22 CTEQ gluon compared to MRST error band Q 2 =5 Q 2 =100

23 Parton uncertainties due to stat/sym errors of data fitted Other uncertainties include selection of data fitted; choice of x,Q 2,W 2 cuts Theoretical uncertainties higher-order DGLAP NLO, NNLO…Moch,Vermaseren,Vogt  s ln(1/x) and  s ln(1-x) effects absorptive corrections from parton recombination residual higher-twist effects QED effects Uncertainties due to input assumptions isospin-violating effects MRST s not equal to s CTEQ heavy-target corrections choice of input parametrization no NuTeV sin 2  anomaly Alwall Kotikov

24 MRST NNLO suggests W or Z prod. can be be used as a luminosity monitor at the Tevatron (& LHC)

25 Kataev Gottfried sum rule in the large N c limit I G = (dx/x) (F 2  p – F 2  n ) = / expt. = 1/3 - 2/3 dx (d – u) valence: pert. corr. small, higher twist small  s /N c 2 (i)checks from Adler SR. (ii) 3-loop anom. dim. of MVV (NNLO) confirms colour structure non-pert asymmetry of sea. what happens as x  0? (  SM)

26 Experimental ways to determine the gluon F L most direct x ~ Prompt photon data (WA70,E706) and theory problems Tevatron jets x ~ 0.07 – 0.5 HERA jets x ~ (ZEUS) Diffractive J/  at HERA g 2 x ~ need to improve theory (+ momentum sum rule)

27 Zeitnitz Inclusive jets Top quark cross section Run I Run II

28 3 jets/2 jets inclusive jet helps pin down gluon at x~0.1 Savin & Rostovtsev

29 Extremely valuable if HERA could measure F L with sufficient precision --- to pin down the low x gluon FLFL Thorne Q 2 =10 Q 2 =5 Q 2 =20 Q 2 =40 Data are Klein’s simulation based on runs at E p = 400,465,575,920 GeV.

30 DGLAP ln 1/x resum ? abs. corr. ? Higgs Stirling


32 Lipatov What happens to the Pomeron traj. at high temp.? Remarkably -- nothing happens for fixed  s. -- result of conformal inv. of the original theory. Running  s destroys inv. – no exact solution – expect some change May be possible to establish relation between BFKL and string dynamics – dimensions of space-time = no. of t ch. gluons?

33 Gluon k t distribution in resummed NLL BFKL y=6 y=4 y=2 LO BFKL NLL BFKL DGLAP, DLLA Final k t =30 GeV at y=ln(1/x)=8 Gluon k t along evolution chain --- find that NLL BFKL and DGLAP v.similar Important since underlying event might have masked New Physics signals at LHC. Monte Carlos OK Ryskin

34 Diffractive DIS data Mastroberardino

35 Schildknecht: Also describes F 2, F 2 D, vector meson prod. well, using dipole approach with GVMD, incorporating saturation

36 m q =0 m q =140 MeV Original Golec-Biernat, Wusthoff fit Include charm. Relate to xg & evolve in Q 2 +Bartels,Kowalski Is it saturation or confinement ? There are other dipole fits without saturation e.g. Forshaw, Kerley & Shaw.

37 Saturation No definitive experimental evidence Much theoretical activity BK, JIMWLK,…equations A glimpse… Rostovsev

38 Equivalent approaches p rest frame / fast dipolefast p / slow dipole bare dipole evolved p wave fn. (cgc)  wave fn. Balitsky Kovchegov eq. Jalilan Marian, Iancu, McLerran, Weigert, Leonidov, Kovner eq. leads to Lublinsky explained this much better

39 Fadin Bartels Two progress reports: is proving that gluon Reggeization is valid at NLO BFKL Checking the consistency of bootstrap relations, s ch. unitarity and Reggeization for production amplitudes. is relating the BK equation to Reggeon field theory Remarkable simplifications from Mobius invariance

40 Saturation momentum Q s (x) in NLL BFKL ~ DGLAP x 0 defined by Q s (x 0 )=1 GeV Ryskin LO BFKL unreliable, BK,JIMWLK eqs. ?! Qs2Qs2 x 0 /x

41 Nikolaev Saturation effects in nuclei. Diffractive DIS is about 50% in nuclei. Collective nuclear glue (nuclear Pomeron) is a good idea but destroys k T factorization. Also fan diagrams no longer sufficient.

42 Diffractive DIS data Mastroberardino




46 ln Q 2 higher twist Bartels,Ellis, Kowalski & Wusthoff base parametrization on these forms

47 Contribution of diffractive F 2 to inclusive F 2 Apply the AGK cutting rules to contrib. AGK in QCD: Bartels & Ryskin  F 2 abs ~ - F 2 D negative (~Glauber shadowing) In pQCD, is a cut, not a pole Lipatov has a continuous no. of compts of different size, r~1/  For each  compt., DGLAP evol. of F 2 D (x,Q 2,  2 ) starts from   Q provided it is large enough Im T el ~  tot Ryskin






53 Input ~ MRST2001 Ryskin


55 xg, xS  const Ryskin Need Q 2  Q 2 +1 mimics power corr.

56 rapidity gap survival factor S 2 ~ 0.1 HERA S 2 ~ 1 ** Survival factors calc. from 2-ch eikonal model based on multi-Pom. exchange & s channel unitarity KKMR

57 Diffractive photoproduction of dijets: direct compt. S 2 ~ 1 resolved compt. (hadron-like) S 2 ~ 0.34 NLO analysis by Klasen & Kramer,-- good agreement with prelim. H1 data Note in LO analysis, data would prefer S 2 ~ 1 for resolved Mastroberardino

58 Exclusive diffractive Higgs signal pp  p+H+p Higgs For a 120 GeV (SM) Higgs at the LHC (L=30 fb -1 ) 11 events / 4 background For MSSM with tan  ~50, m A ~130 GeV 70 events / 3 background Advantages: 2 indep. M H det. 1.missing mass to proton taggers (  M~1 GeV) 2. bb decay (  M~10 GeV) bb backgd v.suppressed by J z =0 selection rule S 2 = Khoze

59 5  signal at LHC 30 fb fb -1 Khoze

60 Kim, Schlein Higgs via single Pomeron exchange Predicted much larger signal, but ---need to study of background, ---include evolution from Q 2 =50 GeV 2 (UA8) up to Q 2 =10 4 GeV 2

61 Amarian Semi-inclusive ep  e  X HERMES

62 Sidorov



65 Ochs N g /N q = C F /C A = 9/4 -- naïve MLLA -- better agreement with e + e - data Full calculation – excellent agreement  parameter determined from multiplicity Pivovarov Calculated the B parameter at NLO --- three loop non-factorising massive Feynman graph B = pert. nonpert. Apologies omitting for so many excellent contributions

66 There are so many crucial measurements still to be done, and unless the correct action is set into motion soon, time will run out for HERA --- while the physics potential of the machine is still coming to its prime. Buschhorn

67 Very special thanks to Petersburg Nuclear Physics Institute Petersburg branch of the RAS Petersburg State University Fock Institute of Physics Staff of the Baltiets Hotel Assistants Pavel Yakimov Julia Grebenyuk Nastya Grebenyuk Sergey Anufriev Sergey Afonin Foreign department Tatiana Bondarenko Natalia Nikitina Drivers Sergey Zvonovsky Eduard Patsyukov Dima Dzyubchuk Photographer Tatiana Potapova

68 Social Programme Lyudmila Kolesnikova Secretariat Galina Stepanova Zoya Gaditskaya Lidia Rusinova Tatiana Gordeeva Victor Gordeev Victor Kim Lev Lipatov …and to ALL the participants for making this such a productive and enjoyable meeting …and so on to HSQCD 2005

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