# Physics Performance Report for PANDA: Strong Interaction Studies with Antiprotons

**ABSTRACT** To study fundamental questions of hadron and nuclear physics in interactions of antiprotons with nucleons and nuclei, the universal PANDA detector will be built. Gluonic excitations, the physics of strange and charm quarks and nucleon structure studies will be performed with unprecedented accuracy thereby allowing high-precision tests of the strong interaction. The proposed PANDA detector is a state-of-the art internal target detector at the HESR at FAIR allowing the detection and identification of neutral and charged particles generated within the relevant angular and energy range. This report presents a summary of the physics accessible at PANDA and what performance can be expected. Comment: 216 pages

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**ABSTRACT:**This is a brief summary of prompt production of D mesons in pp and Pb-Pb collisions with the ALICE apparatus at the LHC.02/2014; - SourceAvailable from: Biagio Lucini
##### Article: Glueballs from the Lattice

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**ABSTRACT:**Recent numerical calculations of the glueball spectrum in QCD, in SU($N$) Yang-Mills theory in the large-$N$ limit and in candidate theories of strongly interacting dynamics beyond the standard model (in which the lowest-lying scalar plays the role of the Higgs boson) are reviewed and their implications for our theoretical understanding of glueballs in QCD-like theories and in strongly coupled gauge theories with a (near-)conformal dynamics are discussed.01/2014; - SourceAvailable from: export.arxiv.org[Show abstract] [Hide abstract]

**ABSTRACT:**We calculate the combined angular distribution functions of the polarized photons ($\gamma_1$ and $\gamma_2$) and electron ($e^-$) produced in the cascade process $\bar{p}p\rightarrow$ $^3D_3\rightarrow$ $^3P_2+\gamma_1\rightarrow$ $(\psi+\gamma_2)+\gamma_1\rightarrow(e^++e^-)+\gamma_1+\gamma_2$, when the colliding $\bar{p}$ and $p$ are unpolarized. Our results are independent of any dynamical models and are expressed in terms of the spherical harmonics whose coefficients are functions of the angular-momentum helicity amplitudes of the individual processes. Once the joint angular distribution of ($\gamma_1$, $\gamma_2$) and that of ($\gamma_2$, $e^-$) with the polarization of either one of the two particles are measured, our results will enable one to determine the relative magnitudes as well as the relative phases of all the angular-momentum helicity amplitudes in the radiative decay processes $^3D_3\rightarrow$ $^3P_2+\gamma_1$ and $^3P_2\rightarrow\psi+\gamma_2$.European Physical Journal C 11/2013; 74(2). · 5.44 Impact Factor

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FAIR/PANDA/Physics Book

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Physics Performance Report for:

PANDA

(AntiProton Annihilations at Darmstadt)

Strong Interaction Studies with Antiprotons

PANDA Collaboration

To study fundamental questions of hadron and nuclear physics in interactions of antiprotons with nucleons

and nuclei, the universal PANDA detector will be build. Gluonic excitations, the physics of strange and

charm quarks and nucleon structure studies will be performed with unprecedented accuracy thereby

allowing high-precision tests of the strong interaction. The proposed PANDA detector is a state-of-the-

art internal target detector at the HESR at FAIR allowing the detection and identification of neutral and

charged particles generated within the relevant angular and energy range.

This report presents a summary of the physics accessible at PANDA and what performance can be

expected.

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PANDA - Strong interaction studies with antiprotons

The PANDA Collaboration

Universit¨ at Basel, Switzerland

W. Erni, I. Keshelashvili, B. Krusche, M. Steinacher

Institute of High Energy Physics, Chinese Academy of Sciences, Beijing, China

Y. Heng, Z. Liu, H. Liu, X. Shen, O. Wang, H. Xu

Ruhr-Universit¨ at Bochum, Institut f¨ ur Experimentalphysik I, Germany

J. Becker, F. Feldbauer, F.-H. Heinsius, T. Held, H. Koch, B. Kopf, C. Motzko, M. Peliz¨ aus, B. Roth,

T. Schr¨ oder, M. Steinke, U. Wiedner, J. Zhong

Universit` a di Brescia, Italy

A. Bianconi

Institutul National de C&D pentru Fizica si Inginerie Nucleara ”Horia Hulubei”, Bukarest-Magurele,

Romania

M. Bragadireanu, D. Pantea, A. Tudorache, V. Tudorache

Dipartimento di Fisica e Astronomia dell’Universit` a di Catania and INFN, Sezione di Catania, Italy

M. De Napoli, F. Giacoppo, G. Raciti, E. Rapisarda, C. Sfienti

IFJ, Institute of Nuclear Physics PAN, Cracow, Poland

E. Bialkowski, A. Budzanowski, B. Czech, M. Kistryn, S. Kliczewski, A. Kozela, P. Kulessa, K. Pysz,

W. Sch¨ afer, R. Siudak, A. Szczurek

Institute of Applied Informatics, Cracow University of Technology, Poland

W. Czy˙ zycki, M. Domaga? la, M. Hawryluk, E. Lisowski, F. Lisowski, L. Wojnar

Institute of Physics, Jagiellonian University, Cracow, Poland

D. Gil, P. Hawranek, B. Kamys, St. Kistryn, K. Korcyl, W. Krzemie´ n, A. Magiera, P. Moskal, Z. Rudy,

P. Salabura, J. Smyrski, A. Wro´ nska

GSI Helmholtzzentrum f¨ ur Schwerionenforschung GmbH, Darmstadt, Germany

M. Al-Turany, I. Augustin, H. Deppe, H. Flemming, J. Gerl, K. G¨ otzen, R. Hohler, D. Lehmann,

B. Lewandowski, J. L¨ uhning, F. Maas, D. Mishra, H. Orth, K. Peters, T. Saito, G. Schepers,

C.J. Schmidt, L. Schmitt, C. Schwarz, B. Voss, P. Wieczorek, A. Wilms

Technische Universit¨ at Dresden, Germany

K.-T. Brinkmann, H. Freiesleben, R. J¨ akel, R. Kliemt, T. W¨ urschig, H.-G. Zaunick

Veksler-Baldin Laboratory of High Energies (VBLHE), Joint Institute for Nuclear Research, Dubna,

Russia

V.M. Abazov, G. Alexeev, A. Arefiev, V.I. Astakhov, M.Yu. Barabanov, B.V. Batyunya, Yu.I. Davydov,

V.Kh. Dodokhov, A.A. Efremov, A.G. Fedunov, A.A. Feshchenko, A.S. Galoyan, S. Grigoryan,

A. Karmokov, E.K. Koshurnikov, V.Ch. Kudaev, V.I. Lobanov, Yu.Yu. Lobanov, A.F. Makarov,

L.V. Malinina, V.L. Malyshev, G.A. Mustafaev, A. Olshevski, M.A.. Pasyuk, E.A. Perevalova,

A.A. Piskun, T.A. Pocheptsov, G. Pontecorvo, V.K. Rodionov, Yu.N. Rogov, R.A. Salmin,

A.G. Samartsev, M.G. Sapozhnikov, A. Shabratova, G.S. Shabratova, A.N. Skachkova, N.B. Skachkov,

E.A. Strokovsky, M.K. Suleimanov, R.Sh. Teshev, V.V. Tokmenin, V.V. Uzhinsky A.S. Vodopianov,

S.A. Zaporozhets, N.I. Zhuravlev, A.G. Zorin

University of Edinburgh, United Kingdom

D. Branford, K. F¨ ohl, D. Glazier, D. Watts, P. Woods

Friedrich Alexander Universit¨ at Erlangen-N¨ urnberg, Germany

W. Eyrich, A. Lehmann, A. Teufel

Northwestern University, Evanston, U.S.A.

S. Dobbs, Z. Metreveli, K. Seth, B. Tann, A. Tomaradze

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FAIR/PANDA/Physics Book

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Universit` a di Ferrara and INFN, Sezione di Ferrara, Italy

D. Bettoni, V. Carassiti, A. Cecchi, P. Dalpiaz, E. Fioravanti, I. Garzia, M. Negrini, M. Savri` e,

G. Stancari

INFN-Laboratori Nazionali di Frascati, Italy

B. Dulach, P. Gianotti, C. Guaraldo, V. Lucherini, E. Pace

INFN, Sezione di Genova, Italy

A. Bersani, M. Macri, M. Marinelli, R.F. Parodi

Justus Liebig-Universit¨ at Gießen, II. Physikalisches Institut, Germany

I. Brodski, W. D¨ oring, P. Drexler, M. D¨ uren, Z. Gagyi-Palffy, A. Hayrapetyan, M. Kotulla, W. K¨ uhn,

S. Lange, M. Liu, V. Metag, M. Nanova, R. Novotny, C. Salz, J. Schneider, P. Sch¨ onmeier, R. Schubert,

S. Spataro, H. Stenzel, C. Strackbein, M. Thiel, U. Th¨ oring, S. Yang,

University of Glasgow, United Kingdom

T. Clarkson, E. Cowie, E. Downie, G. Hill, M. Hoek, D. Ireland, R. Kaiser, T. Keri, I. Lehmann,

K. Livingston, S. Lumsden, D. MacGregor, B. McKinnon, M. Murray, D. Protopopescu, G. Rosner,

B. Seitz, G. Yang

Kernfysisch Versneller Instituut, University of Groningen, Netherlands

M. Babai, A.K. Biegun, A. Bubak, E. Guliyev, V.S. Jothi, M. Kavatsyuk, H. L¨ ohner, J. Messchendorp,

H. Smit, J.C. van der Weele

Helsinki Institute of Physics, Finland

F. Garcia, D.-O. Riska

Forschungszentrum J¨ ulich, J¨ ulich Center for Hadron Physics, Germany

M. B¨ uscher, R. Dosdall, R. Dzhygadlo, A. Gillitzer, D. Grunwald, V. Jha, G. Kemmerling, H. Kleines,

A. Lehrach, R. Maier, M. Mertens, H. Ohm, D. Prasuhn, T. Randriamalala, J. Ritman, M. R¨ oder,

T. Stockmanns, P. Wintz, P. W¨ ustner

University of Silesia, Katowice, Poland

J. Kisiel

Chinese Academy of Science, Institute of Modern Physics, Lanzhou, China

S. Li, Z. Li, Z. Sun, H. Xu

Lunds Universitet, Department of Physics, Lund, Sweden

S. Fissum, K. Hansen, L. Isaksson, M. Lundin, B. Schr¨ oder

Johannes Gutenberg-Universit¨ at, Institut f¨ ur Kernphysik, Mainz, Germany

P. Achenbach, M.C. Mora Espi, J. Pochodzalla, S. Sanchez, A. Sanchez-Lorente

Research Institute for Nuclear Problems, Belarus State University, Minsk, Belarus

V.I. Dormenev, A.A. Fedorov, M.V. Korzhik, O.V. Missevitch

Institute for Theoretical and Experimental Physics, Moscow, Russia

V. Balanutsa, V. Chernetsky, A. Demekhin, A. Dolgolenko, P. Fedorets, A. Gerasimov, V. Goryachev

Moscow Power Engineering Institute, Russia

A. Boukharov, O. Malyshev, I. Marishev, A. Semenov

Technische Universit¨ at M¨ unchen, Germany

C. H¨ oppner, B. Ketzer, I. Konorov, A. Mann, S. Neubert, S. Paul, Q. Weitzel

Westf¨ alische Wilhelms-Universit¨ at M¨ unster, Germany

A. Khoukaz, T. Rausmann, A. T¨ aschner, J. Wessels

IIT Bombay, Department of Physics, Mumbai, India

R. Varma

Budker Institute of Nuclear Physics, Novosibirsk, Russia

E. Baldin, K. Kotov, S. Peleganchuk, Yu. Tikhonov

Institut de Physique Nucl´ eaire, Orsay, France

J. Boucher, T. Hennino, R. Kunne, D. Marchand, S. Ong, J. Pouthas, B. Ramstein, P. Rosier,

Page 4

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PANDA - Strong interaction studies with antiprotons

M. Sudol, E. Tomasi-Gustafsson, J. Van de Wiele, T. Zerguerras

Warsaw University of Technology, Institute of Atomic Energy, Otwock-Swierk, Poland

K. Dmowski, R. Korzeniewski, D. Przemyslaw, B. Slowinski

Dipartimento di Fisica Nucleare e Teorica, Universit` a di Pavia, INFN, Sezione di Pavia, Italy

G. Boca, A. Braghieri, S. Costanza, A. Fontana, P. Genova, L. Lavezzi, P. Montagna, A. Rotondi

Institute for High Energy Physics, Protvino, Russia

N.I. Belikov, A.M. Davidenko, A.A. Derevschikov, Y.M. Goncharenko, V.N. Grishin, V.A. Kachanov,

D.A. Konstantinov, V.A. Kormilitsin, V.I. Kravtsov, Y.A. Matulenko, Y.M. Melnik A.P. Meschanin,

N.G. Minaev, V.V. Mochalov, D.A. Morozov, L.V. Nogach, S.B. Nurushev, A.V. Ryazantsev,

P.A. Semenov, L.F. Soloviev, A.V. Uzunian, A.N. Vasiliev, A.E. Yakutin

Kungliga Tekniska H¨ ogskolan, Stockholm, Sweden

T. B¨ ack, B. Cederwall

Stockholms Universitet, Stockholm, Sweden

C. Bargholtz, L. Ger´ en, P.E. Tegn´ er

Petersburg Nuclear Physics Institute of Academy of Science, Gatchina, St. Petersburg, Russia

S. Belostotski, G. Gavrilov, A. Itzotov, A. Kisselev, P. Kravchenko, S. Manaenkov, O. Miklukho,

Y. Naryshkin, D. Veretennikov, V. Vikhrov, A. Zhadanov

Universit` a del Piemonte Orientale Alessandria and INFN, Sezione di Torino, Italy

L. Fava, D. Panzieri

Universit` a di Torino and INFN, Sezione di Torino, Italy

D. Alberto, A. Amoroso, E. Botta, T. Bressani, S. Bufalino, M.P. Bussa, L. Busso, F. De Mori,

M. Destefanis, L. Ferrero, A. Grasso, M. Greco, T. Kugathasan, M. Maggiora, S. Marcello, G. Serbanut,

S. Sosio

INFN, Sezione di Torino, Italy

R. Bertini, D. Calvo, S. Coli, P. De Remigis, A. Feliciello, A. Filippi, G. Giraudo, G. Mazza, A. Rivetti,

K. Szymanska, F. Tosello, R. Wheadon

INAF-IFSI and INFN, Sezione di Torino, Italy

O. Morra

Politecnico di Torino and INFN, Sezione di Torino, Italy

M. Agnello, F. Iazzi, K. Szymanska

Universit` a di Trieste and INFN, Sezione di Trieste, Italy

R. Birsa, F. Bradamante, A. Bressan, A. Martin

Universit¨ at T¨ ubingen, Germany

H. Clement

The Svedberg Laboratory, Uppsala, Sweden

C. Ekstr¨ om

Uppsala University, Department of Physics and Astronomy, Sweden

H. Cal´ en, S. Grape, B. H¨ oistad, T. Johansson, A. Kupsc, P. Marciniewski, E. Thom´ e, J. Zlomanczuk

Universitat de Valencia, Dpto. de F´ ısica At´ omica, Molecular y Nuclear, Spain

J. D´ ıaz, A. Ortiz

Soltan Institute for Nuclear Studies, Warsaw, Poland

S. Borsuk, A. Chlopik, Z. Guzik, J. Kopec, T. Kozlowski, D. Melnychuk, M. Plominski, J. Szewinski,

K. Traczyk, B. Zwieglinski

¨Osterreichische Akademie der Wissenschaften, Stefan Meyer Institut f¨ ur Subatomare Physik, Vienna,

Austria

P. B¨ uhler, M. Cargnelli, A. Gruber, P. Kienle, J. Marton, K. Nikolics, E. Widmann, J. Zmeskal

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AND

GSI Helmholtzzentrum f¨ ur Schwerionenforschung GmbH, Darmstadt, Germany

M.F.M. Lutz

CPhT, Ecole Polytechnique, CNRS, Palaiseau, France

B. Pire

Kernfysisch Versneller Instituut, University of Groningen, Netherlands

O. Scholten, R. Timmermans

Editors: Diego Bettoni (chief editor)

Rob Timmermans (chief editor) Email: timmermans@kvi.nl

Maria Pia Bussa

Michael Dueren

Alessandro Feliciello

Albrecht Gillitzer

Felice Iazzi

Tord Johansson

Bertram Kopf

Andreas Lehrach

Matthias F.M. Lutz

Frank Maas

Marco Maggiora

Matteo Negrini

Klaus Peters

Josef Pochodzalla

Lars Schmitt

Olaf Scholten

Giulio Stancari

Email: bettoni@fe.infn.it

Email: bussa@to.infn.it

Email: Michael.Dueren@exp2.physik.uni-giessen.de

Email: Alessandro.Feliciello@to.infn.it

Email: a.gillitzer@fz-juelich.de

Email: felice.iazzi@polito.it

Email: tord.johansson@tsl.uu.se

Email: bertram@ep1.rub.de

Email: a.lehrach@fz-juelich.de

Email: m.lutz@gsi.de

Email: maas@KPH.UNI-MAINZ.DE

Email: marco.maggiora@to.infn.it

Email: negrini@fe.infn.it

Email: K.Peters@gsi.de

Email: pochodza@KPH.UNI-MAINZ.DE

Email: L.Schmitt@gsi.de

Email: scholten@kvi.nl

Email: stancari@fe.infn.it

Spokesperson:

Deputy:

Ulrich Wiedner

Paola Gianotti

Email: ulrich.wiedner@ruhr-uni-bochum.de

Email: paola.gianotti@lnf.infn.it

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PANDA - Strong interaction studies with antiprotons

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Preface

PANDA is one of the major projects of the FAIR-Facility in Darmstadt. FAIR is an extension of the

existing Heavy Ion Research Lab (GSI) and is expected to start its operation in 2014. PANDA studies

interactions between antiprotons and fixed target protons and nuclei in the momentum range of 1.5-

15 GeV/c using the high energy storage ring HESR. The antiproton project was initiated by a large

community of scientists outside GSI, who had worked very successfully with antiprotons at LEAR/CERN

and the Fermilab antiproton accumulator. Many of the physics ideas of PANDA were already described

in a Letter of Intent (Construction of a GLUE/CHARM-Factory at GSI, Ruhr-University Bochum, 1999)

and were extended afterwards in the FAIR Conceptual Design Report (GSI, 2001), the Technical Progress

Report (FAIR, 2005) and further PANDA specific reports. After the approval of FAIR further projects

involving antiprotons were proposed (experiments with low energy and polarized antiprotons) which are

now in the preparatory phase.

The PANDA scientific program includes several measurements, which address fundamental questions of

QCD, mostly in the non-perturbative regime:

• Hadron spectroscopy up to the region of charm quarks. Here the search for exotic states like glueballs,

hybrids and multiquark states in the light quark domain and in the hidden and open charm region

is in the focus of interest. The recently found XYZ states will be further explored.

• Study of properties of hadrons inside nuclear matter. Mass and width modifications have been

reported and will be investigated also in the charm region.

• Study of nonperturbative dynamics, also including spin degrees of freedom.

• Antiproton induced reactions are a very effective tool to implant strange baryons in nuclei. PANDA

will particularly study double Λ hypernuclei, which are of great importance for nuclear structure

studies and the ΛΛ interaction.

• Hard exclusive antiproton-proton reactions can be used to study the structure of nucleons (time-like

form factors) and the relevance of certain models, like the Hand Bag approach. Interesting aspects

of Transverse Parton Distributions will be studied in Drell-Yan production.

• In a later stage of the project, when all systematic effects are well studied, also contributions to

electroweak physics can be expected, like direct CP violation in hyperon decays and CP violation

and mixing in the charm sector.

All measurements will profit from the high yield of antiproton induced reactions and from the fact

that, in contrast to e+e−reactions, all non-exotic quantum number combinations for directly formed

states are allowed, whereas states with exotic quantum numbers can be observed in production. The

achievable precision, as far mass and width measurements are concerned, is very high as was successfully

demonstrated by the Fermilab experiments. It is independent of the mass resolution of the detector and

only limited by the tiny energy spread of the primary cooled antiproton beam. It will allow a measurement

of the widths of the recently discovered very narrow states. The international PANDA collaboration was

established in 2002. More than 400 scientists from 16 countries and 53 institutions are involved in R&D

hardware and software projects. The most recent achievement is the definition of the final setup of the

electromagnetic calorimeter. The delivery of a first tranche of PWO crystals for the calorimeter has

already started. An overview of all studies and results achieved in the last years can be found on the

PANDA Web site (http://www-panda.gsi.de/auto/ home.htm).

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PANDA - Strong interaction studies with antiprotons

This PANDA Physics Book describes in detail the physics topics envisioned. The first chapter gives a

comprehensive overview of the challenges of QCD; the PANDA detector and the high energy storage ring

HESR are described in detail in chapter 2; in chapter 3 the status of the software is discussed. Chapter

4 shows very detailed simulations of selected benchmark reactions. They take into account the event

generation, digitization, reconstruction, event selection and background estimations. A refinement of

the analysis is achieved by using kinematical fitting and neural network tools. A summary and outlook

concludes the Physics Book. The setup used in the simulations described in this book is not final: some

detector components are still undergoing R&D and will be finalised in the coming months. At the same

time a new software framework is being developed. In the next two years we also expect advances in

background simulations and better estimates of presently unknown cross-sections. A new version of the

physics book is planned, which will reflect the progress described above and which will feature a more

complete list of benchmark channels.

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The use of registered names, trademarks, etc. in this publication

does not imply, even in the absence of specific statement, that

such names are exempt from the relevant laws and regulations

and therefore free for general use.

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PANDA - Strong interaction studies with antiprotons

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Contents

Preface vii

1 Introduction

1.1 The Challenge of QCD . . . . . . . .

1.1.1 Quantum Chromodynamics . . . .

1.1.2 The QCD Coupling Constant

1.1.3The Symmetries of QCD . . . . .

1.1.4Theoretical Approaches to non-

Perturbative QCD . . . . . . . . .

1.2Lattice QCD: Status and Prospects .

1.3EFT with Quark and Gluon Degrees

of Freedom . . . . . . . . . . . . . . .

1.3.1Non-Relativistic QCD . . . . . . .

1.4 EFT with Hadronic Degrees of Freedom

1.4.1ChiralSymmetry

Charm Meson Systems . . . . . .

1.4.2Phenomenology of Open Charm

Baryon Systems . . . . . . . . . .

References . . . . . . . . . . . . . . . . . . .

1

1

1

2

2

. .

3

3

5

6

7

and Open

7

9

10

2 Experimental Setup

2.1 Overview . . . . . . . . . . . . . . . .

2.2 The PANDA Detector . . . . . . . . .

2.2.1Target Spectrometer

2.2.2 Forward Spectrometer . . . . . . .

2.2.3 Luminosity Monitor . . . . . . . .

2.2.4Data Acquisition . . . . . . . . . .

2.2.5Infrastructure . . . . . . . . . . .

2.3 The HESR . . . . . . . . . . . . . . .

2.3.1Introduction . . . . . . . . . . . .

2.3.2 Beam Equilibria and Luminosity

Estimates . . . . . . . . . . . . . .

2.4PrecisionMeasurements

nance Parameters . . . . . . . . . . .

2.4.1Experimental Technique

2.4.2Mass Measurements . . . . . . . .

2.4.3 Total and Partial Widths . . . . .

2.4.4Line Shapes . . . . . . . . . . . .

2.4.5Achievable Precision . . . . . . . .

References . . . . . . . . . . . . . . . . . . .

13

13

13

13

21

23

24

25

27

27

. . . . . . .

27

ofReso-

31

31

33

34

35

36

36

. . . . .

3Software

3.1

3.1.1

3.1.2

3.1.3

3.2

39

39

39

39

41

Event Generation . . . . . . . . . . .

EvtGen Generator . . . . . . . . .

Dual Parton Model . . . . . . . .

UrQMD. . . . . . . . . . . . . .

Particle Tracking and Detector Sim-

ulation . . . . . . . . . . . . . . . . .

Detector Setup . . . . . . . . . . .

Digitization. . . . . . . . . . . .

Reconstruction . . . . . . . . . . . . .

Charged Particle Track Recon-

struction . . . . . . . . . . . . . .

Photon Reconstruction . . . . . .

Charged Particle Identification . .

Physics Analysis . . . . . . . . . . . .

Analysis Tools . . . . . . . . . . .

Data Production . . . . . . . . . . . .

Bookkeeping . . . . . . . . . . . .

Event Production . . . . . . . . .

Filter on Generator Level . . . . .

Software Developments . . . . . . . .

References . . . . . . . . . . . . . . . . . . .

43

43

43

45

3.2.1

3.2.2

3.3

3.3.1

45

47

49

55

56

56

56

56

57

58

60

3.3.2

3.3.3

3.4

3.4.1

3.5

3.5.1

3.5.2

3.5.3

3.6

4Physics Performance

4.1 Overview . . . . . . . . . . . . . . . .

4.2 QCD Bound States . . . . . . . . . .

4.2.1The QCD Spectrum . . . . . . . .

4.2.2Charmonium . . . . . . . . . . . .

4.2.3Exotic Excitations . . . . . . . . .

4.2.4Heavy-Light Systems . . . . . . . 103

4.2.5Strange and Charmed Baryons . . 112

4.3Non-perturbative QCD Dynamics . . 117

4.3.1Previous Experiments . . . . . . . 117

4.3.2Experimental Aims . . . . . . . . 118

4.3.3 Reconstruction of the pp → Y Y

Reaction . . . . . . . . . . . . . . 118

4.3.4 Two-Meson Production in pp -

Annihilation at Large Angle . . . 127

4.4Hadrons in the Nuclear Medium . . . 129

63

63

64

64

64

86

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PANDA - Strong interaction studies with antiprotons

4.4.1 In-Medium

Charmed Hadrons . . . . . . . . . 129

Charmonium Dissociation

J/ψ N Dissociation Cross Section

in pA Collisions . . . . . . . . . . 131

Antibaryons and Antikaons Pro-

duced in pA Collisions

Colour Transparency . . . . . . . 136

Hypernuclear Physics . . . . . . . . . 139

Physics Goals . . . . . . . . . . . 139

ExperimentalIntegration

Simulation . . . . . . . . . . . . . 141

The Structure of the Nucleon Using

Electromagnetic Processes . . . . . . 148

Partonic Picture of Hard Exclu-

sive pp-Annihilation Processes . . 148

Transverse Parton Distribution

Functions in Drell-Yan Production 153

Electromagnetic Form Factors in

the Time-like Region . . . . . . . 165

Electroweak Physics . . . . . . . . . . 176

CP-Violation and Mixing in the

Charm-Sector . . . . . . . . . . . 176

CP-Violation in Hyperon Decays . 176

Rare Decays . . . . . . . . . . . . 176

References . . . . . . . . . . . . . . . . . . . 177

Propertiesof

4.4.2

4.4.3

. . . . 130

4.4.4

. . . . . . 135

4.4.5

4.5

4.5.1

4.5.2and

4.6

4.6.1

4.6.2

4.6.3

4.7

4.7.1

4.7.2

4.7.3

5 Summary and Outlook191

Acknowledgements193

List of Acronyms195

List of Figures197

List of Tables203

Page 13

1

1 Introduction

1.1 The Challenge of QCD

The modern theory of the strong interactions is

Quantum Chromodynamics (QCD), the quantum

field theory of quarks and gluons based on the

non-abelian gauge group SU(3). Together with the

SU(2)×U(1) electroweak theory, QCD is part of the

Standard Model of particle physics. QCD is well

tested at high energies, where the strong coupling

constant becomes small and perturbation theory

applies. In the low-energy regime, however, QCD

becomes a strongly-coupled theory, many aspects

of which are not understood. The thriving ques-

tions are: How can we bring order into the rich

phenomena of low energy QCD? Are there effective

degrees of freedom in terms of which we can un-

derstand the resonances and bound states of QCD

efficiently and systematically? Does QCD generate

exotic structures so far undiscovered? PANDA will

be in a unique position to provide answers to such

important questions about non-perturbative QCD.

A major part of the physics programme of PANDA

is designed to collect high-quality data that allow

a clean interpretation in terms of the predictions of

non-perturbative QCD. In this introductory chap-

ter, we first summarize the basics of QCD and then

review the theoretical approaches that can be jus-

tified rigorously within QCD and provide testable

predictions for experiments like PANDA.

1.1.1 Quantum Chromodynamics

The development of QCD as the theory of strong in-

teractions is a success story. Its quantitative predic-

tions at high energies, in the perturbative regime,

are such that it is beyond serious doubt that QCD is

the correct theory of the strong interactions. Never-

theless, in the non-perturbative low-energy regime,

it remains very hard to make quantitative predic-

tions starting from first principles, i.e. from the

QCD Lagrangian. Conceptually, QCD is simple:

it is a relativistic quantum field theory of quarks

and gluons interacting according to the laws of non-

abelian forces between colour charges. The starting

point of all considerations is the celebrated QCD

Lagrangian density:

LQCD= −1

+¯ qf[iγµDµ− mf]qf,

4Gµν

aGa

µν

?

f

(1.1)

where

Gµν

a = ∂µAν

a− ∂νAµ

a+ g f

bc

a

Aµ

bAν

c,

(1.2)

is the gluon field strength tensor, and

Dµ= ∂µ− ig

the gauge covariant derivative involving the gluon

field Aµ

g2/4π; f denotes the quark flavour, where for

the energy regime of PANDA, the relevant quark

flavours are u, d, s, c: up, down, strange, and

charm. We take ? = 1 = c.

This deceptively simple looking QCD Lagrangian

is at the basis of the rich and complex phenomena

of nuclear and hadronic physics.

plexity arises in a theory with quarks and gluons

as fundamental degrees of freedom is only qualita-

tively understood. The QCD field equations are

non-linear, since the gluons that mediate the in-

teraction carry colour charge, and hence interact

among themselves. This makes every strongly-

interacting system intrinsically a many-body prob-

lem, wherein apart from the valence quarks many

quark-antiquark pairs and many gluons are always

involved. These non-abelian features of QCD are

believed to lead to the phenomenon that the ba-

sic degrees of freedom, the quarks and the gluons,

cannot be observed in the QCD spectrum: the con-

finement of colour charge is the reason behind the

complex world of nuclear and hadronic physics.

The process of renormalization in quantum field

theory generates an intrinsic QCD scale ΛQCD

through the mechanism of dimensional transmuta-

tion; ΛQCD is, loosely speaking, the scale below

which the coupling constant becomes so large that

standard perturbation theory no longer applies. All

hadron masses are in principle calculable within

QCD in terms of ΛQCD. This dynamical genera-

tion of the mass scale of the strong interactions is

the famous QCD gap phenomenon: the proton mass

is non-zero because of the energy of the confined

quarks and gluons. Although a mathematical proof

of colour confinement is lacking, qualitatively this is

thought to be linked to the fact that the quark and

gluon bilinears qaqaand Ga

vacuum expectation values.

Now, some 35 years after the discovery of QCD,

it is fair to say that strong interactions are under-

stood in principle, but a long list of unresolved ques-

tions about low-energy QCD remains. Our present

2Aµ

aλa,

(1.3)

a; g is the strong coupling constant, αS =

How this com-

µνGµν

a

acquire non-zero

Page 14

2

PANDA - Strong interaction studies with antiprotons

understanding of QCD thereby serves as the ba-

sis to set priorities for theoretical and experimen-

tal research. Clearly, not all phenomena in nuclear

physics need to be understood in detail from QCD.

Many areas of nuclear physics will be happily de-

scribed in terms of well-established phenomenology

with its own degrees of freedom, just like many com-

plex phenomena in atomic physics and chemistry

do not have to be understood directly in terms of

QED. Likewise, while not all experiments in nuclear

and hadronic physics should be guided by QCD,

dedicated experiments that test QCD in the non-

perturbative regime and to improve our limited un-

derstanding of these aspects of QCD are crucial. In

its choice of topics, the PANDA physics programme

aims to achieve precisely this.

1.1.2 The QCD Coupling Constant

The qualitative understanding of QCD as outlined

above is to a large extent based on the classical

calculation of the renormalization scale dependence

of the QCD coupling constant αS as given by the

β-function at an energy scale µ,

β(αS) ≡µ

2

∂αS

∂µ

= −β0

4πα2

S−

β1

8π2α3

S− ... (1.4)

where

β0

= 11 −2

51 −19

3nf ,

(1.5)

β1

=

3nf ,

(1.6)

where nf is the number of quarks with mass less

than µ; expressions for β2 and β3 exist. In solv-

ing this differential equation for αS(µ), one intro-

duces the scale Λ to provide the µ dependence of

αS.The solution then demonstrates the famous

properties of asymptotic freedom, αS → 0 when

µ → ∞, and of strong coupling at scales below

µ ∼ Λ.

pendence of the QCD coupling constant, one may

roughly divide the field of strong interaction physics

into the areas of perturbative QCD (pQCD) and of

non-perturbative QCD. QCD has been very success-

ful in quantitatively describing phenomena where

perturbation theory with its standard machinery

of Feynman rules applies. An important example

is e+e−annihilation in the area of the Z0boson,

where the multi-particle hadronic final-state system

reveals the perturbative QCD physics in the form

of the quark and gluon jets. In this perturbative

regime predictions can be made on the basis of the

magnitude of the QCD coupling constant. Its value

Based on this result for the scale de-

Figure 1.1: The running of the strong coupling con-

stant as function of the scale µ [1].

as a function of energy determines a host of phe-

nomena, such as scaling violations in deep inelastic

scattering, the τ lifetime, high-energy hadron col-

lisions, heavy-quarkonium (in particular bottomo-

nium) decay, e+e−collisions, and jet rates in ep

collisions. The coupling constants derived from

these processes are consistent and lead to an av-

erage value [1]

αS(MZ) = 0.1176 ± 0.0002 .

The non-perturbative regime is the area of strong

nuclear forces and hadronic resonances, which is

quantitatively much less well understood and where

important questions still have to be addressed. In

between are areas like deep inelastic lepton-hadron

scattering where perturbation theory is used, how-

ever, with non-perturbative input.

(1.7)

1.1.3The Symmetries of QCD

It has been said that QCD is a most elegant the-

ory in physics, since its structure is solely deter-

mined by symmetry principles: QCD is the most

general renormalisable quantum field theory based

on the gauge group SU(3). In addition to exact

Lorentz invariance and SU(3) colour gauge invari-

ance, it has several other important symmetry prop-

erties. The QCD Lagrangian as given above has a

number of “accidental” symmetries, i.e. symme-

tries that are an automatic consequence of the as-

sumed gauge invariance. The discrete symmetries

parity and charge conjugation are such accidental

symmetries (we ignore here the mysterious θ-term

Page 15

FAIR/PANDA/Physics Book

3

that results in the still unsolved strong CP-problem

of QCD). Flavour conservation is another: the num-

ber of quarks (minus antiquarks) of each flavour

(e.g. strangeness) is conserved, corresponding to an

automatic invariance of the QCD Lagrangian under

phase rotations of the quark fields of each flavour

separately.

Additional symmetries result from the considera-

tion that the masses of the up, down, and strange

quarks can be considered small compared to the

typical hadronic scale ΛQCD. To the extent that

these masses can be ignored, the QCD Lagrangian

is invariant under unitary transformations of the

quark fields of the form q?

counts for the rather accurate SU(2)-isospin and

the approximate SU(3)-flavour symmetries of nu-

clear and hadronic physics.

u, d, and s masses can be ignored, QCD is invari-

ant under separate unitary transformations among

the left- and right-handed quarks, qL?

and qR?

i

= UR

try group U(3)L×U(3)R. The diagonal subgroup

(UL= UR) corresponds to the SU(3)-flavour (and

baryon number) symmetry mentioned. The remain-

ing chiral SU(3) symmetry (U−1

to be spontaneously broken by the vacuum state

of QCD, resulting in the existence of an octet of

Goldstone bosons identified with the pseudoscalar

mesons π, K, η.

These approximate flavour and chiral symmetries

due to the smallness of the u, d, and s quark masses,

are important, since they can be exploited to for-

mulate effective field theories that are equivalent to

QCD in a certain energy range. A classic example

is chiral perturbation theory for the interaction of

baryons with the octet of the pseudoscalar mesons,

which results in an expansion of matrix elements in

terms of small momenta or light-quark masses [2].

On similar footing is heavy-quark effective theory

(HQET) for hadrons containing a quark (c, b, t)

with mass mQ ? ΛQCD. In the limit mQ → ∞,

the heavy quark becomes on-shell and the dynam-

ics becomes independent of its mass. The hadronic

matrix elements can be expanded as a power series

in 1/mQ, resulting in symmetry relations between

various matrix elements [3].

Generalizing QCD to an SU(Nc) gauge theory, the

inverse of the number of colours, 1/Nc, is a hid-

den expansion parameter [4]. This theory, wherein

the coupling is decreased such that g2Nc is con-

stant, is “large-Nc QCD”. Diagrammatic consid-

erations suggest that large-Nc QCD is a weakly-

coupled theory of mesons and baryons, wherein

baryons are heavy semiclassical objects.

i= Uijqj. This ac-

Moreover, when the

i

= UL

ijqL

j

ijqR

j, resulting in the chiral symme-

L

= UR) is believed

Signifi-

cant, mostly qualitative, insight into QCD can be

obtained from considering the large-Nclimit, espe-

cially when combined with the techniques of effec-

tive field theory.

1.1.4 Theoretical Approaches to

non-Perturbative QCD

In this brief introduction, we focus on theoreti-

cal frameworks that have a rigorous justification in

QCD and that, with allowance for further progress

in the coming years and with a reasonable extrapo-

lation of available computing resources, can be ex-

pected to provide a direct confrontation of the data

from experiments like PANDA with the predictions

of non-perturbative QCD. Among these theoretical

approaches the best established are (i) lattice QCD,

which attempts a direct attack to solve QCD non-

perturbatively by numerical simulation, and (ii) ef-

fective field theories, which exploit the symmetries

of QCD and the existence of hierarchies of scales to

provide predictions from effective Lagrangians that

are equivalent to QCD; among the latter we distin-

guish systematic effective field theories formulated

in terms of quark-gluon and in terms of hadronic

degrees of freedom.

It should be kept in mind that the theoretical ap-

proaches will, in many cases, calculate quantities

that require an additional step to be compared with

measured data.This is because a full computa-

tion of the cross section as measured by experi-

mentalists in antiproton-proton collisions demands

significantly more effort. Such an additional step

may involve a partial-wave analysis of the measured

data, in order to, for instance determine the quan-

tum numbers of a resonance. Effective field theory

with hadronic degrees of freedom offers some ad-

vantages in this respect. In the case of PANDA, an

example is the associated production of hyperon-

antihyperon pairs in the reactions pp → Y Y , where

the spin observables in the final state can be pre-

cisely measured [5]. Therefore, the possibility exists

in this case to perform a full partial-wave analysis

of the data to study in detail the contribution of

resonances.

1.2Lattice QCD: Status and

Prospects

Lattice QCD (LQCD) is an ab initio approach to

deal with QCD in the non-perturbative low-energy

regime. The equations of motion of QCD are dis-

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