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Chen LB, Chen W, Feng F, Jia Y. Next-to-Next-to-Leading-Order QCD Corrections to Pion Electromagnetic Form Factors. PHYSICAL REVIEW LETTERS 2024; 132:201901. [PMID: 38829056 DOI: 10.1103/physrevlett.132.201901] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/09/2024] [Revised: 03/27/2024] [Accepted: 04/12/2024] [Indexed: 06/05/2024]
Abstract
We calculate the next-to-next-to-leading-order (NNLO) QCD radiative correction to the pion electromagnetic form factor with large momentum transfer. We explicitly verify the validity of the collinear factorization to two-loop order for this observable and obtain the respective IR-finite two-loop hard-scattering kernel in the closed form. The NNLO QCD correction turns out to be positive and significant. Incorporating this new ingredient of correction, we then make a comprehensive comparison between the finest theoretical predictions and numerous data for both space- and timelike pion form factors. Our phenomenological analysis provides a strong constraint on the second Gegenbauer moment of the pion light-cone distribution amplitude obtained from recent lattice QCD studies.
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Affiliation(s)
- Long-Bin Chen
- School of Physics and Materials Science, Guangzhou University, Guangzhou 510006, China
| | - Wen Chen
- Institute of Quantum Matter, South China Normal University, Guangzhou 510006, China
- Zhejiang Institute of Modern Physics, School of Physics, Zhejiang University, Hangzhou, Zhejiang 310027, China
| | - Feng Feng
- China University of Mining and Technology, Beijing 100083, China
- Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, China
| | - Yu Jia
- Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
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2
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Wang X, Xing Z, Kang J, Raya K, Chang L. Pion scalar, vector, and tensor form factors from a contact interaction. Int J Clin Exp Med 2022. [DOI: 10.1103/physrevd.106.054016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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3
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Albino L, Higuera-Angulo I, Raya K, Bashir A. Pseudoscalar mesons: Light front wave functions, GPDs, and PDFs. Int J Clin Exp Med 2022. [DOI: 10.1103/physrevd.106.034003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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4
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Gao X, Karthik N, Mukherjee S, Petreczky P, Syritsyn S, Zhao Y. Pion form factor and charge radius from lattice QCD at the physical point. Int J Clin Exp Med 2021. [DOI: 10.1103/physrevd.104.114515] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Abstract
The Lagrangian that defines quantum chromodynamics (QCD), the strong interaction piece of the Standard Model, appears very simple. Nevertheless, it is responsible for an astonishing array of high-level phenomena with enormous apparent complexity, e.g., the existence, number and structure of atomic nuclei. The source of all these things can be traced to emergent mass, which might itself be QCD’s self-stabilising mechanism. A background to this perspective is provided, presenting, inter alia, a discussion of the gluon mass and QCD’s process-independent effective charge and highlighting an array of observable expressions of emergent mass, ranging from its manifestations in pion parton distributions to those in nucleon electromagnetic form factors.
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Ding M, Raya K, Binosi D, Chang L, Roberts CD, Schmidt SM. Symmetry, symmetry breaking, and pion parton distributions. Int J Clin Exp Med 2020. [DOI: 10.1103/physrevd.101.054014] [Citation(s) in RCA: 55] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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8
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Li WB, Huber GM, Blok HP, Gaskell D, Horn T, Semenov-Tian-Shansky K, Pire B, Szymanowski L, Laget JM, Aniol K, Arrington J, Beise EJ, Boeglin W, Brash EJ, Breuer H, Chang CC, Christy ME, Ent R, Gibson EF, Holt RJ, Jin S, Jones MK, Keppel CE, Kim W, King PM, Kovaltchouk V, Liu J, Lolos GJ, Mack DJ, Margaziotis DJ, Markowitz P, Matsumura A, Meekins D, Miyoshi T, Mkrtchyan H, Niculescu I, Okayasu Y, Pentchev L, Perdrisat C, Potterveld D, Punjabi V, Reimer PE, Reinhold J, Roche J, Roos PG, Sarty A, Smith GR, Tadevosyan V, Tang LG, Tvaskis V, Volmer J, Vulcan W, Warren G, Wood SA, Xu C, Zheng X. Unique Access to u-Channel Physics: Exclusive Backward-Angle Omega Meson Electroproduction. PHYSICAL REVIEW LETTERS 2019; 123:182501. [PMID: 31763910 DOI: 10.1103/physrevlett.123.182501] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/27/2019] [Revised: 10/01/2019] [Indexed: 06/10/2023]
Abstract
Backward-angle meson electroproduction above the resonance region, which was previously ignored, is anticipated to offer unique access to the three quark plus sea component of the nucleon wave function. In this Letter, we present the first complete separation of the four electromagnetic structure functions above the resonance region in exclusive ω electroproduction off the proton, ep→e^{'}pω, at central Q^{2} values of 1.60, 2.45 GeV^{2}, at W=2.21 GeV. The results of our pioneering -u≈-u_{min} study demonstrate the existence of a unanticipated backward-angle cross section peak and the feasibility of full L/T/LT/TT separations in this never explored kinematic territory. At Q^{2}=2.45 GeV^{2}, the observed dominance of σ_{T} over σ_{L}, is qualitatively consistent with the collinear QCD description in the near-backward regime, in which the scattering amplitude factorizes into a hard subprocess amplitude and baryon to meson transition distribution amplitudes: universal nonperturbative objects only accessible through backward-angle kinematics.
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Affiliation(s)
- W B Li
- University of Regina, Regina, Saskatchewan S4S 0A2, Canada
- College of William and Mary, Williamsburg, Virginia 23185, USA
| | - G M Huber
- University of Regina, Regina, Saskatchewan S4S 0A2, Canada
| | - H P Blok
- VU University, NL-1081 HV Amsterdam, Netherlands
- NIKHEF, Postbus 41882, NL-1009 DB Amsterdam, Netherlands
| | - D Gaskell
- Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606, USA
| | - T Horn
- Catholic University of America, Washington, D.C. 20064, USA
| | - K Semenov-Tian-Shansky
- National Research Centre Kurchatov Institute: Petersburg Nuclear Physics Institute, RU-188300 Gatchina, Russia
- Saint Petersburg National Research Academic University of the Russian Academy of Sciences, RU-194021 St. Petersburg, Russia
| | - B Pire
- CPHT, CNRS, École Polytechnique, IP Paris, 91128-Palaiseau, France
| | - L Szymanowski
- National Centre for Nuclear Research (NCBJ), 02-093 Warsaw, Poland
| | - J-M Laget
- Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606, USA
| | - K Aniol
- California State University Los Angeles, Los Angeles, California 90032, USA
| | - J Arrington
- Physics Division, Argonne National Laboratory, Argonne, Illinois 60439, USA
| | - E J Beise
- University of Maryland, College Park, Maryland 20742, USA
| | - W Boeglin
- Florida International University, Miami, Florida 33119, USA
| | - E J Brash
- Christopher Newport University, Newport News, Virginia 23606, USA
| | - H Breuer
- University of Maryland, College Park, Maryland 20742, USA
| | - C C Chang
- University of Maryland, College Park, Maryland 20742, USA
| | - M E Christy
- Hampton University, Hampton, Virginia 23668, USA
| | - R Ent
- Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606, USA
| | - E F Gibson
- California State University, Sacramento, California 95819, USA
| | - R J Holt
- Caltech, Pasadena, California 91125, USA
| | - S Jin
- Kyungpook National University, Daegu, 702-701, Republic of Korea
| | - M K Jones
- Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606, USA
| | - C E Keppel
- Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606, USA
- Hampton University, Hampton, Virginia 23668, USA
| | - W Kim
- Kyungpook National University, Daegu, 702-701, Republic of Korea
| | - P M King
- Ohio University, Athens, Ohio 45701, USA
| | - V Kovaltchouk
- Ontario Tech University, Oshawa, Ontario L1G 0C5, Canada
| | - J Liu
- Shanghai Jiao Tong University, Shanghai 200240, China
| | - G J Lolos
- University of Regina, Regina, Saskatchewan S4S 0A2, Canada
| | - D J Mack
- Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606, USA
| | - D J Margaziotis
- California State University Los Angeles, Los Angeles, California 90032, USA
| | - P Markowitz
- Florida International University, Miami, Florida 33119, USA
| | - A Matsumura
- Tohoku University, Sendai, Miyagi 980-8578, Japan
| | - D Meekins
- Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606, USA
| | - T Miyoshi
- Tohoku University, Sendai, Miyagi 980-8578, Japan
| | - H Mkrtchyan
- A.I. Alikhanyan National Science Laboratory, Yerevan 0036, Armenia
| | - I Niculescu
- James Madison University, Harrisonburg, Virginia 22807, USA
| | - Y Okayasu
- Tohoku University, Sendai, Miyagi 980-8578, Japan
| | - L Pentchev
- Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606, USA
| | - C Perdrisat
- College of William and Mary, Williamsburg, Virginia 23187, USA
| | - D Potterveld
- Physics Division, Argonne National Laboratory, Argonne, Illinois 60439, USA
| | - V Punjabi
- Norfolk State University, Norfolk, Virginia 23504, USA
| | - P E Reimer
- Physics Division, Argonne National Laboratory, Argonne, Illinois 60439, USA
| | - J Reinhold
- Florida International University, Miami, Florida 33119, USA
| | - J Roche
- Ohio University, Athens, Ohio 45701, USA
| | - P G Roos
- University of Maryland, College Park, Maryland 20742, USA
| | - A Sarty
- Saint Mary's University, Halifax, Nova Scotia B3H 3C3, Canada
| | - G R Smith
- Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606, USA
| | - V Tadevosyan
- A.I. Alikhanyan National Science Laboratory, Yerevan 0036, Armenia
| | - L G Tang
- Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606, USA
- Hampton University, Hampton, Virginia 23668, USA
| | - V Tvaskis
- NIKHEF, Postbus 41882, NL-1009 DB Amsterdam, Netherlands
- VU University, NL-1081 HV Amsterdam, Netherlands
| | - J Volmer
- VU University, NL-1081 HV Amsterdam, Netherlands
- DESY, Hamburg 22607, Germany
| | - W Vulcan
- Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606, USA
| | - G Warren
- Pacific Northwest National Laboratory, Richland, Washington 99352, USA
| | - S A Wood
- Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606, USA
| | - C Xu
- University of Regina, Regina, Saskatchewan S4S 0A2, Canada
| | - X Zheng
- University of Virginia, Charlottesville, Virginia 22904, USA
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Colangelo G, Hoferichter M, Procura M, Stoffer P. Hadronic light-by-light contribution to (g - 2)μ: a dispersive approach. EPJ WEB OF CONFERENCES 2018. [DOI: 10.1051/epjconf/201817501025] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
After a brief introduction on ongoing experimental and theoretical activities on (g - 2)μ, we report on recent progress in approaching the calculation of the hadronic light-by-light contribution with dispersive methods. General properties of the four-point function of the electromagnetic current in QCD, its Lorentz decomposition and dispersive representation are discussed. On this basis a numerical estimate for the pion box contribution and its rescattering corrections is obtained. We conclude with an outlook for this approach to the calculation of hadronic light-by-light.
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Ahmady M, Chishtie F, Sandapen R. Spin effects in the pion holographic light-front wavefunction. Int J Clin Exp Med 2017. [DOI: 10.1103/physrevd.95.074008] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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11
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12
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Biernat EP, Gross F, Peña M, Stadler A. Charge-conjugation symmetric complete impulse approximation for the pion electromagnetic form factor in the covariant spectator theory. Int J Clin Exp Med 2015. [DOI: 10.1103/physrevd.92.076011] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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14
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Yabusaki GH, Ahmed I, Paracha MA, de Melo J, El-Bennich B. Pseudoscalar mesons with symmetric bound state vertex functions on the light front. Int J Clin Exp Med 2015. [DOI: 10.1103/physrevd.92.034017] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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15
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Seth KK. Form factors of pions, kaons & protons at the highest timelike momentum transfers & first measurements of hyperons. EPJ WEB OF CONFERENCES 2015. [DOI: 10.1051/epjconf/20159503033] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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16
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Huber GM, Blok HP, Butuceanu C, Gaskell D, Horn T, Mack DJ, Abbott D, Aniol K, Anklin H, Armstrong C, Arrington J, Assamagan K, Avery S, Baker OK, Barrett B, Beise EJ, Bochna C, Boeglin W, Brash EJ, Breuer H, Chang CC, Chant N, Christy ME, Dunne J, Eden T, Ent R, Fenker H, Gibson EF, Gilman R, Gustafsson K, Hinton W, Holt RJ, Jackson H, Jin S, Jones MK, Keppel CE, Kim PH, Kim W, King PM, Klein A, Koltenuk D, Kovaltchouk V, Liang M, Liu J, Lolos GJ, Lung A, Margaziotis DJ, Markowitz P, Matsumura A, McKee D, Meekins D, Mitchell J, Miyoshi T, Mkrtchyan H, Mueller B, Niculescu G, Niculescu I, Okayasu Y, Pentchev L, Perdrisat C, Pitz D, Potterveld D, Punjabi V, Qin LM, Reimer PE, Reinhold J, Roche J, Roos PG, Sarty A, Shin IK, Smith GR, Stepanyan S, Tang LG, Tadevosyan V, Tvaskis V, van der Meer RLJ, Vansyoc K, Van Westrum D, Vidakovic S, Volmer J, Vulcan W, Warren G, Wood SA, Xu C, Yan C, Zhao WX, Zheng X, Zihlmann B. Separated response function ratios in exclusive, forward π(±) electroproduction. PHYSICAL REVIEW LETTERS 2014; 112:182501. [PMID: 24856691 DOI: 10.1103/physrevlett.112.182501] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/24/2014] [Indexed: 06/03/2023]
Abstract
The study of exclusive π(±) electroproduction on the nucleon, including separation of the various structure functions, is of interest for a number of reasons. The ratio RL=σL(π-)/σL(π+) is sensitive to isoscalar contamination to the dominant isovector pion exchange amplitude, which is the basis for the determination of the charged pion form factor from electroproduction data. A change in the value of RT=σT(π-)/σT(π+) from unity at small -t, to 1/4 at large -t, would suggest a transition from coupling to a (virtual) pion to coupling to individual quarks. Furthermore, the mentioned ratios may show an earlier approach to perturbative QCD than the individual cross sections. We have performed the first complete separation of the four unpolarized electromagnetic structure functions above the dominant resonances in forward, exclusive π(±) electroproduction on the deuteron at central Q(2) values of 0.6, 1.0, 1.6 GeV(2) at W=1.95 GeV, and Q(2)=2.45 GeV(2) at W=2.22 GeV. Here, we present the L and T cross sections, with emphasis on RL and RT, and compare them with theoretical calculations. Results for the separated ratio RL indicate dominance of the pion-pole diagram at low -t, while results for RT are consistent with a transition between pion knockout and quark knockout mechanisms.
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Affiliation(s)
- G M Huber
- University of Regina, Regina, Saskatchewan S4S 0A2, Canada
| | - H P Blok
- VU university, NL-1081 HV Amsterdam, The Netherlands and NIKHEF, Postbus 41882, NL-1009 DB Amsterdam, The Netherlands
| | - C Butuceanu
- University of Regina, Regina, Saskatchewan S4S 0A2, Canada
| | - D Gaskell
- Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606, USA
| | - T Horn
- Catholic University of America, Washington, DC 20064, USA
| | - D J Mack
- Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606, USA
| | - D Abbott
- Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606, USA
| | - K Aniol
- California State University Los Angeles, Los Angeles, California 90032, USA
| | - H Anklin
- Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606, USA and Florida International University, Miami, Florida 33119, USA
| | - C Armstrong
- College of William and Mary, Williamsburg, Virginia 23187, USA
| | - J Arrington
- Physics Division, Argonne National Laboratory, Argonne, Illinois 60439, USA
| | - K Assamagan
- Hampton University, Hampton, Virginia 23668, USA
| | - S Avery
- Hampton University, Hampton, Virginia 23668, USA
| | - O K Baker
- Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606, USA and Hampton University, Hampton, Virginia 23668, USA
| | - B Barrett
- Saint Mary's University, Halifax, Nova Scotia B3H 3C3 Canada
| | - E J Beise
- University of Maryland, College Park, Maryland 20742, USA
| | - C Bochna
- University of Illinois, Champaign, Illinois 61801, USA
| | - W Boeglin
- Florida International University, Miami, Florida 33119, USA
| | - E J Brash
- University of Regina, Regina, Saskatchewan S4S 0A2, Canada
| | - H Breuer
- University of Maryland, College Park, Maryland 20742, USA
| | - C C Chang
- University of Maryland, College Park, Maryland 20742, USA
| | - N Chant
- University of Maryland, College Park, Maryland 20742, USA
| | - M E Christy
- Hampton University, Hampton, Virginia 23668, USA
| | - J Dunne
- Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606, USA
| | - T Eden
- Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606, USA and Norfolk State University, Norfolk, Virginia 23504, USA
| | - R Ent
- Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606, USA
| | - H Fenker
- Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606, USA
| | - E F Gibson
- California State University, Sacramento, California 95819, USA
| | - R Gilman
- Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606, USA and Rutgers, The State University of New Jersey, Piscataway, New Jersey 08854, USA
| | - K Gustafsson
- University of Maryland, College Park, Maryland 20742, USA
| | - W Hinton
- Hampton University, Hampton, Virginia 23668, USA
| | - R J Holt
- Physics Division, Argonne National Laboratory, Argonne, Illinois 60439, USA
| | - H Jackson
- Physics Division, Argonne National Laboratory, Argonne, Illinois 60439, USA
| | - S Jin
- Kyungpook National University, Daegu 702-701, Republic of Korea
| | - M K Jones
- College of William and Mary, Williamsburg, Virginia 23187, USA
| | - C E Keppel
- Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606, USA and Hampton University, Hampton, Virginia 23668, USA
| | - P H Kim
- Kyungpook National University, Daegu 702-701, Republic of Korea
| | - W Kim
- Kyungpook National University, Daegu 702-701, Republic of Korea
| | - P M King
- University of Maryland, College Park, Maryland 20742, USA
| | - A Klein
- Old Dominion University, Norfolk, Virginia 23529, USA
| | - D Koltenuk
- University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
| | - V Kovaltchouk
- University of Regina, Regina, Saskatchewan S4S 0A2, Canada
| | - M Liang
- Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606, USA
| | - J Liu
- University of Maryland, College Park, Maryland 20742, USA
| | - G J Lolos
- University of Regina, Regina, Saskatchewan S4S 0A2, Canada
| | - A Lung
- Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606, USA
| | - D J Margaziotis
- California State University Los Angeles, Los Angeles, California 90032, USA
| | - P Markowitz
- Florida International University, Miami, Florida 33119, USA
| | | | - D McKee
- New Mexico State University, Las Cruces, New Mexico 88003-8001, USA
| | - D Meekins
- Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606, USA
| | - J Mitchell
- Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606, USA
| | | | - H Mkrtchyan
- A.I. Alikhanyan National Science Laboratory, Yerevan 0036, Armenia
| | - B Mueller
- Physics Division, Argonne National Laboratory, Argonne, Illinois 60439, USA
| | - G Niculescu
- James Madison University, Harrisonburg, Virginia 22807, USA
| | - I Niculescu
- James Madison University, Harrisonburg, Virginia 22807, USA
| | | | - L Pentchev
- College of William and Mary, Williamsburg, Virginia 23187, USA
| | - C Perdrisat
- College of William and Mary, Williamsburg, Virginia 23187, USA
| | - D Pitz
- DAPNIA/SPhN, CEA/Saclay, F-91191 Gif-sur-Yvette, France
| | - D Potterveld
- Physics Division, Argonne National Laboratory, Argonne, Illinois 60439, USA
| | - V Punjabi
- Norfolk State University, Norfolk, Virginia 23504, USA
| | - L M Qin
- Old Dominion University, Norfolk, Virginia 23529, USA
| | - P E Reimer
- Physics Division, Argonne National Laboratory, Argonne, Illinois 60439, USA
| | - J Reinhold
- Florida International University, Miami, Florida 33119, USA
| | - J Roche
- Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606, USA
| | - P G Roos
- University of Maryland, College Park, Maryland 20742, USA
| | - A Sarty
- Saint Mary's University, Halifax, Nova Scotia B3H 3C3 Canada
| | - I K Shin
- Kyungpook National University, Daegu 702-701, Republic of Korea
| | - G R Smith
- Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606, USA
| | - S Stepanyan
- A.I. Alikhanyan National Science Laboratory, Yerevan 0036, Armenia
| | - L G Tang
- Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606, USA and Hampton University, Hampton, Virginia 23668, USA
| | - V Tadevosyan
- A.I. Alikhanyan National Science Laboratory, Yerevan 0036, Armenia
| | - V Tvaskis
- VU university, NL-1081 HV Amsterdam, The Netherlands and NIKHEF, Postbus 41882, NL-1009 DB Amsterdam, The Netherlands
| | | | - K Vansyoc
- Old Dominion University, Norfolk, Virginia 23529, USA
| | - D Van Westrum
- University of Colorado, Boulder, Colorado 80309, USA
| | - S Vidakovic
- University of Regina, Regina, Saskatchewan S4S 0A2, Canada
| | - J Volmer
- VU university, NL-1081 HV Amsterdam, The Netherlands and DESY, Hamburg, Germany
| | - W Vulcan
- Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606, USA
| | - G Warren
- Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606, USA
| | - S A Wood
- Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606, USA
| | - C Xu
- University of Regina, Regina, Saskatchewan S4S 0A2, Canada
| | - C Yan
- Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606, USA
| | - W-X Zhao
- Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - X Zheng
- Physics Division, Argonne National Laboratory, Argonne, Illinois 60439, USA
| | - B Zihlmann
- Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606, USA and University of Virginia, Charlottesville, Virginia 22901, USA
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17
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Chang L, Cloët IC, Roberts CD, Schmidt SM, Tandy PC. Pion electromagnetic form factor at spacelike momenta. PHYSICAL REVIEW LETTERS 2013; 111:141802. [PMID: 24138233 DOI: 10.1103/physrevlett.111.141802] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/01/2013] [Revised: 08/29/2013] [Indexed: 06/02/2023]
Abstract
A novel method is employed to compute the pion electromagnetic form factor, F(π)(Q²), on the entire domain of spacelike momentum transfer using the Dyson-Schwinger equation (DSE) framework in QCD. The DSE architecture unifies this prediction with that of the pion's valence-quark parton distribution amplitude (PDA). Using this PDA, the leading-order, leading-twist perturbative QCD result for Q²F(π)(Q²) underestimates the full computation by just 15% on Q²≳8 GeV², in stark contrast to the result obtained using the asymptotic PDA. The analysis shows that hard contributions to the pion form factor dominate for Q²≳8 GeV², but, even so, the magnitude of Q²F(π)(Q²) reflects the scale of dynamical chiral symmetry breaking, a pivotal emergent phenomenon in the standard model.
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Affiliation(s)
- L Chang
- Institut für Kernphysik, Forschungszentrum Jülich, D-52425 Jülich, Germany
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18
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Cloët IC, Chang L, Roberts CD, Schmidt SM, Tandy PC. Pion distribution amplitude from lattice QCD. PHYSICAL REVIEW LETTERS 2013; 111:092001. [PMID: 24033026 DOI: 10.1103/physrevlett.111.092001] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/11/2013] [Indexed: 06/02/2023]
Abstract
A method is explained through which a pointwise accurate approximation to the pion's valence-quark distribution amplitude (PDA) may be obtained from a limited number of moments. In connection with the single nontrivial moment accessible in contemporary simulations of lattice-regularized QCD, the method yields a PDA that is a broad concave function whose pointwise form agrees with that predicted by Dyson-Schwinger equation analyses of the pion. Under leading-order evolution, the PDA remains broad to energy scales in excess of 100 GeV, a feature which signals persistence of the influence of dynamical chiral symmetry breaking. Consequently, the asymptotic distribution φπ(asy)(x) is a poor approximation to the pion's PDA at all such scales that are either currently accessible or foreseeable in experiments on pion elastic and transition form factors. Thus, related expectations based on φ φπ(asy)(x) should be revised.
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Affiliation(s)
- I C Cloët
- Physics Division, Argonne National Laboratory, Argonne, Illinois 60439, USA
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Miller GA, Strikman M, Weiss C. Pion transverse charge density from timelike form factor data. Int J Clin Exp Med 2011. [DOI: 10.1103/physrevd.83.013006] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Raha U, Aste A. Electromagnetic pion and kaon form factors in light-cone resummed perturbative QCD. Int J Clin Exp Med 2009. [DOI: 10.1103/physrevd.79.034015] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Nam SI, Kim HC. Electromagnetic form factors of the pion and kaon from the instanton vacuum. Int J Clin Exp Med 2008. [DOI: 10.1103/physrevd.77.094014] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Agaev SS, Nobary MAG. Pion distribution amplitude from holographic QCD and the electromagnetic form factorFπ(Q2). Int J Clin Exp Med 2008. [DOI: 10.1103/physrevd.77.074014] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Clasie B, Qian X, Arrington J, Asaturyan R, Benmokhtar F, Boeglin W, Bosted P, Bruell A, Christy ME, Chudakov E, Cosyn W, Dalton MM, Daniel A, Day D, Dutta D, El Fassi L, Ent R, Fenker HC, Ferrer J, Fomin N, Gao H, Garrow K, Gaskell D, Gray C, Horn T, Huber GM, Jones MK, Kalantarians N, Keppel CE, Kramer K, Larson A, Li Y, Liang Y, Lung AF, Malace S, Markowitz P, Matsumura A, Meekins DG, Mertens T, Miller GA, Miyoshi T, Mkrtchyan H, Monson R, Navasardyan T, Niculescu G, Niculescu I, Okayasu Y, Opper AK, Perdrisat C, Punjabi V, Rauf AW, Rodriquez VM, Rohe D, Ryckebusch J, Seely J, Segbefia E, Smith GR, Strikman M, Sumihama M, Tadevosyan V, Tang L, Tvaskis V, Villano A, Vulcan WF, Wesselmann FR, Wood SA, Yuan L, Zheng XC. Measurement of nuclear transparency for the A(e,e'pi+) reaction. PHYSICAL REVIEW LETTERS 2007; 99:242502. [PMID: 18233444 DOI: 10.1103/physrevlett.99.242502] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/10/2007] [Revised: 09/23/2007] [Indexed: 05/25/2023]
Abstract
We have measured the nuclear transparency of the A(e,e'pi+) process in 2H, 12C, 27Al, 63Cu, and 197Au targets. These measurements were performed at the Jefferson Laboratory over a four momentum transfer squared range Q2=1.1 to 4.7 (GeV/c)2. The nuclear transparency was extracted as the super-ratio of (sigmaA/sigmaH) from data to a model of pion-electroproduction from nuclei without pi-N final-state interactions. The Q2 and atomic number dependence of the nuclear transparency both show deviations from traditional nuclear physics expectations and are consistent with calculations that include the quantum chromodynamical phenomenon of color transparency.
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Affiliation(s)
- B Clasie
- Laboratory for Nuclear Science, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
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