Hadron Physics QCD: are we satisfied with it? Antiproton’s potentiality The PANDA enterprise 1 Paola Gianotti

Our present knowledge of matter is the result of centuries of studies… Philosophers of ancient Greece believed it was made of 4 elements what is matter made of? Mendeleev 1869 introduced the periodic table of elements 1808 Dalton, following their weights, make a first list of elements 1963 Murray, Gell-Mann, and Zweig laid the foundation of quark model 2

Quantum Chromodynamics The QCD Lagrangian is, in principle, a complete description of the strong interaction. There is just one overall coupling constant g, and six quark-mass parameters m j for the six quark flavors But, it leads to equations that are hard to solve 3

Furthermore, we've never seen particles carrying fractional electric charge, which we nonetheless ascribe to the quarks. And certainly we haven't seen anything like gluons--massless particles mediating long-range strong forces. The Confinement So if QCD is to describe the world, it must explain why quarks and gluons cannot exist as isolated particles. That is the so-called confinement problem. None of the particles that we've actually seen appear in the formula and none of the particles that appear in the formula has ever been observed. 4

Hadron masses The elementary particles of the Standard Model gain their mass through the Higgs mechanism. However, only a few percent of the mass of the proton is due to the Higgs mechanism. The rest is created in an unknown way by the strong interaction. Glueballs would be massless without the strong interaction and their predicted masses arise solely from the strong interaction. C. Morningstar and M. Peardon, Phys. Rev. D 60, (1999) The possibility to study a whole spectrum of glueballs might therefore be the key of understanding the mechanism of mass creation by the strong interaction. 5

The chiral symmetry There is another qualitative difference between the observed reality and the world of quarks and gluons. The phenomenology indicates that if QCD is to describe the world, then the u and d quarks must have very small masses. But if u and d quarks have very small masses, then the equations of QCD possess some additional symmetry, called chiral symmetry. There is no such symmetry among the observed strongly interacting particles; they do not come in opposite-parity pairs. So if QCD is to describe the real world, the chiral symmetry must be spontaneously broken. and this mechanism is playing an important role in the process of mass generation 6

Chiral symmetry restoration The mass of light hadrons (u,d,(s)) is dominated by spontaneous chiral symmetry breaking. In the nuclear medium (ρ>0) we can restore, at least partially this symmetry. Hints of this effect have been already observed. We wants to extend these studies to Charmed mesons pionic atoms KAOS/FOPI HESR π K D vacuumnuclear medium ρ = ρ 0 π+π+ π-π- K-K- K+K+ D+D+ D-D- 25 MeV 100 MeV 50 MeV Mass modifications of mesons 7

How do we solve QCD problems? The first approach is to try to solve the equations. That's not easy. Fortunately, powerful modern computers have made it possible to calculate a few of the key predictions of QCD directly. The agreement with the measured masses is at the 10% level. The second approach is that of creating phenomenological models that are simpler to deal with, but still bear some significant resemblance to the real thing. arXiv:hep-lat/ v1 quark antiqark Meson Hybrid Glueball 8

Nowadays, QCD prediction can reach precisions at the GeV around 10 %, and also the phenomenological models are not doing better! Can we be satisfied of this accuracy? Can we be satisfied? Just a note: the Tolemaic system allowed to predict the positions of the planets with the same level of accuracy….. but it was wrong! 9

Experimental tests are needed… High statistics and high quality data are necessary to help constraining the models Different experimental techniques can be used to focus on different aspects: The selection of special working conditions or of final states helps filtering initial/final state quantum numbers; In protons-antiproton annihilations complex objects collide The interaction occurs between two beams of (anti)quarks and gluons p p p  e-e- 10

High Energy: pp-Colliders ( CERN, Fermilab ) Discovery of Z 0, W ± Discovery of t-quark High Energy: pp-Colliders ( CERN, Fermilab ) Discovery of Z 0, W ± Discovery of t-quark Medium Energy: Conventional p-beams ( LBL, BNL, CERN, Fermilab, KEK,... ) p-Storage Rings ( LEAR (CERN); Antiproton Accumulator (Fermilab) ) Meson Spectroscopy (u, d, s, c) p-nucleus interaction Hypernuclei Antihydrogen first production CP-violation Medium Energy: Conventional p-beams ( LBL, BNL, CERN, Fermilab, KEK,... ) p-Storage Rings ( LEAR (CERN); Antiproton Accumulator (Fermilab) ) Meson Spectroscopy (u, d, s, c) p-nucleus interaction Hypernuclei Antihydrogen first production CP-violation Low Energy (Stopped p‘s): Conventional p-beams p-Storage Rings ( LEAR, AD (CERN) ) p-Atoms (pHe) p/p-mass ratio Antihydrogen Low Energy (Stopped p‘s): Conventional p-beams p-Storage Rings ( LEAR, AD (CERN) ) p-Atoms (pHe) p/p-mass ratio Antihydrogen Physics with antiprotons had a great past 11

Physics with antiprotons have a great future High Energy: pp-Collider ( Fermilab ) B physics, Top, Electroweak, QCD, Higgs High Energy: pp-Collider ( Fermilab ) B physics, Top, Electroweak, QCD, Higgs Medium Energy: Conventional p-beams ( Fermilab, (KEK),... ) p-Storage Rings ( HESR, (Fermilab) ) Charmonium spectroscopy Exotic search D physics Baryon spectroscopy Hypernuclei CP-violation Medium Energy: Conventional p-beams ( Fermilab, (KEK),... ) p-Storage Rings ( HESR, (Fermilab) ) Charmonium spectroscopy Exotic search D physics Baryon spectroscopy Hypernuclei CP-violation Low Energy (Stopped p‘s): Conventional p-beams p-Storage Rings ( FLAIR, AD (CERN) ) p-Atoms Antihydrogen spectroscopy Low Energy (Stopped p‘s): Conventional p-beams p-Storage Rings ( FLAIR, AD (CERN) ) p-Atoms Antihydrogen spectroscopy 12

Spectroscopy studies Production all J PC available Exotic states are produced with rates similar to q q conventional systems All ordinary quantum numbers can be reached σ ~1 μb All ordinary quantum numbers can be reached σ ~1 μb p p _ G M p M H p _ p M H p _ Even exotic quantum numbers can be reached σ ~100 pb Even exotic quantum numbers can be reached σ ~100 pb Two are the mechanisms to access particular final states: Formation only selected J PC p p _ p p _ H p p _ H G 13

In the light meson region, about 10 states have been classified as “Exotics”. Almost all of them have been seen in p p... Exotic hadrons Main non-qq candidates f 0 (980)4q state - molecule f 0 (1500)0 ++ glueball candidate f 0 (1370)0 ++ glueball candidate f 0 (1710)0 ++ glueball candidate  (1410);  (1460) 0  + glueball candidate f 1 (1420)hybrid, 4q state  1 (1400) hybrid candidate 1   1 (1600) hybrid candidate 1   (1800) hibrid candidate 0   2 (1900) hybrid candidate 2   1 (2000) hybrid candidate 1  a 2 ’(2100)hybrid candidate

Charmonium region From G. S. Bali, Int.J.Mod.Phys. A21 (2006) arXiv:hep-lat/ Only with high statistics and different final states, quantum number assignment become clear Charmonium spectrum, glueballs, spin-exotics cc-glue hybrids with experimental results 15

Antiproton’s power MeV3510 CBall ev./2 MeV 100 E CM CBall E E 835 ev./pb  c1 e + e   →  ’ →  1,2 →  e + e  →  J   e + e  interactions: - Only 1  states are formed - Other states only by secondary decays (moderate mass resolution) - All states directly formed (very good mass resolution) →  J  →  e + e  p p→  1,2 _  pp reactions: _ Br(e + e  →  ·Br(  →  c ) = 2.5   Br( ) pp →  c = 1.2   _ 16

p-beams can be cooled  Excellent resonance resolution Antiproton’s power The resonance mass M R, total width  R and product of branching ratios into the initial and final state B in B out can be extracted by measuring the formation rate for that resonance as a function of the cm energy E. The production rate of a certain final state is a convolution of the BW cross section and the beam energy distribution function f(E,  E): Measured rate Beam Resonance cross section CM Energy  Crystal Ball: typical resolution ~ 10 MeV  Fermilab: 240 keV  PANDA: ~30 keV 17

The hadron’s structure The characteristics hadrons are given only in minor part by the constituent quarks. Quarks and gluons dynamics plays a fundamental role in the definitions of hadron’s properties: mass, spin, etc… Nucleon Form Factors have been mainly studied using electromagnetic probes, but the physical diagrams can be reverted… and a complementary approach can be used Generalized Parton Distributions functions (GPDs) contain both the usual form factors and parton distributions, but in addition they include correlations between states of different longitudinal and transverse momenta. GPDs give a three-dimensional picture of the nucleon. In a similar way Deeply Virtual Compton Scattering (DVCS) can be crossed-studied perturbative QCDnon-perturbative QCD 18

p Momentum [GeV/c] Mass [GeV/c 2 ] ΛΛ ΣΣ ΞΞ ΛcΛcΣcΣcΞcΞcΛcΛcΣcΣcΞcΞc ΩcΩcΩcΩc ΩΩD DsDsDsDs qq ccqqccqq n n g,s s gccgccg ggg,gg light q q π,ρ,ω, f 2,K,K *c J/ψ, η c, χ cJ n n g,s s gccgccg ggg Our Playground Meson spectroscopy light mesons charmonium exotic states − glueballs − hybrids − molecules/multiquarks open charm Baryon/antibaryon production Charm in nuclei Hypernuclei Em. form factors of the proton Generalized Parton Distributions 19

Production Rates (1-2 (fb) -1 /y) Final State cross section # rec. events/y Key elements : Low multiplicity events Possibility to trigger on defined final states Key elements : Low multiplicity events Possibility to trigger on defined final states 20

below DD threshold all the predicted states have been detected, but there is lack of precise measurements of masses, widths and branching ratios (i.e.  c,  c (2S), h c ) Charmonium spectroscopy Charmonium energy is the transition range between perturbative and non-perturbative regime. It is the energy range where models are tuned 21

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Charmonium above DD threshold This is the more obscure region: old and new measurements at electron machines seem not in agreement. On the other side several new states showed up at the B-factories for most states J PC is not well established…and 23

Newly-born new Charmonium-like states from Belle Y(4361) Y(4664) Z(4430) → ψ(2S)π ± 24

Open charm states Open charm sates are the QCD analogon of hydrogen atom for QED Narrow states D s0 (2317) and D s1 (2458) recently discovered at B- factories do not fit theoretical calculations. Quantum numbers for the newest states D sJ (2700) and D sJ (2880) are open At full luminosity at p momenta larger than 6.4 GeV/c PANDA will produce large numbers of DD pairs. Despite small signal/background ratio (5  ) background situation favourable because of limited phase space for additional hadrons in the same process. 25

By making an energy scan around threshold → counting signal events, determine the excitation function and extract the width An example… threshold D s *D s0 * The width of D s0 *(2317) can be measured in the reaction pp  D s D s0 *(2317) 26

: the new antiproton facility Primary Beams /s; 1.5 GeV/u; 238 U 28+ Factor present in intensity 2(4)x10 13 /s 30 GeV protons /s 238 U 73+ up to 25 (- 35) GeV/u Secondary Beams Broad range of radioactive beams up to GeV/u; up to factor in intensity over present Antiprotons 3 (0) - 30 GeV Storage and Cooler Rings Radioactive beams e – A collider stored and cooled GeV antiprotons Cooled beams Rapidly cycling superconducting magnets Key Technical Features Facility for Antiproton and Ion Research 27

HESR - High Energy Storage Ring High luminosity mode High resolution mode  p/p ~ 10  (electron cooling) Lumin. = cm  s  Lumin. = 2 x cm  s   p/p ~ 10  (stochastic cooling) Production rate 2x10 7 /sec P beam = GeV/c N stored = 5x10 10 p Internal Target _ from RESR Pellet-Target H 2 (ρ=0.08 g/cm 2 ) pellets/s p d = 1 mm 28

Detector requirements: nearly 4  solid angle(partial wave analysis) high rate capability(2 · 10 7 annihilations/s) good PID( , e, , , K, p) momentum resolution(~1%) vertex info for D, K 0 S,  (c  = 317  m for D ± ) efficient trigger(e, , K, D,  ) modular design(Hypernuclei experiments) General Purpose Detector 29

Pellet or cluster-jet target 2T Superconducting solenoid for high p t particles 2T Superconducting solenoid for high p t particles 2Tm Dipole for forward tracks 30

Silicon Microvertex detector Central Tracker Forward Chambers 31

Barrel DIRC Barrel TOF Endcap DIRC Forward TOF Forward RICH Muon Detectors 32

PWO EMC Forward Shashlyk EMC Hadron Calorimeter 33

Collaboration At present a group of 420 physicists from 55 institutions of 17 countries Basel, Beijing, Bochum, IIT Bombay, Bonn, Brescia, IFIN Bucharest, Catania, Cracow, IFJ PAN Cracow, Cracow UT, Dresden, Edinburgh, Erlangen, Ferrara, Frankfurt, Genova, Giessen, Glasgow, GSI, Inst. of Physics Helsinki, FZ Jülich, JINR Dubna, Katowice, KVI Groningen, Lanzhou, LNF, Lund, Mainz, Minsk, ITEP Moscow, MPEI Moscow, TU München, Münster, Northwestern, BINP Novosibirsk, IPN Orsay, Pavia, Piemonte Orientale, IHEP Protvino, PNPI St.Petersburg, KTH Stockholm, Stockholm, INFN Torino, Torino, Torino Politecnico, Trieste, TSL Uppsala, Tübingen, Uppsala, Valencia, SINS Warsaw, TU Warsaw, SMI Wien Basel, Beijing, Bochum, IIT Bombay, Bonn, Brescia, IFIN Bucharest, Catania, Cracow, IFJ PAN Cracow, Cracow UT, Dresden, Edinburgh, Erlangen, Ferrara, Frankfurt, Genova, Giessen, Glasgow, GSI, Inst. of Physics Helsinki, FZ Jülich, JINR Dubna, Katowice, KVI Groningen, Lanzhou, LNF, Lund, Mainz, Minsk, ITEP Moscow, MPEI Moscow, TU München, Münster, Northwestern, BINP Novosibirsk, IPN Orsay, Pavia, Piemonte Orientale, IHEP Protvino, PNPI St.Petersburg, KTH Stockholm, Stockholm, INFN Torino, Torino, Torino Politecnico, Trieste, TSL Uppsala, Tübingen, Uppsala, Valencia, SINS Warsaw, TU Warsaw, SMI Wien Austria – Belaruz - China - Finland - France - Germany – India - Italy – The Nederlands - Poland – Romania - Russia – Spain - Sweden – Switzerland - U.K. – U.S.A.. 34

Summary perform high resolution spectroscopy with p -beam in formation experiments:  E ≈  E beam produce, with high yields, gluonic excitations: glueballs, hybrids, multi-quark states  ≈ 100 pb study partial chiral symmetry restoration by implanting mesons inside the nuclear medium produce hyperon-antihyperon taggable beams perform high resolution spectroscopy with p -beam in formation experiments:  E ≈  E beam produce, with high yields, gluonic excitations: glueballs, hybrids, multi-quark states  ≈ 100 pb study partial chiral symmetry restoration by implanting mesons inside the nuclear medium produce hyperon-antihyperon taggable beams Thanks to the new HESR antiproton ring at FAIR we will be able to... 35

Space: The final frontier… In the Star Trek universe, spaceships use the enormous energy of matter- antimatter annihilation to leap across the universe. This is science fiction, but antiproton-proton annihilation is not 36

A new challenging Enterprise is started! If you are interested….Jump on! 37