In Ref. [1], the authors claim to observe a narrow structure in the mass spectrum constructed from the (pKL) system using data from the CLAS detector. The interpretation of this narrow structure given in Ref. [1] is as follows: “It may be due to the photoproduction of the Θ+pentaquark or some unknown Σ* resonance.” The authors go on to say that “it is unlikely for the observed structure to be due to a Σ* resonance.

Anghinolfi, M.

et. al.,

Gilfoyle, Gerard P.

English

University of Richmond

Masthead LogoUniversity of RichmondUR Scholarship RepositoryPhysics Faculty Publications Physics2012Comment on “Observation of a Narrow Structurein 1H(γ,KS0)X via Interference with ϕ-MesonProduction”M. AnghinolfiGerard P. GilfoyleUniversity of Richmond, ggilfoyl@richmond.eduet. al.Follow this and additional works at: https://scholarship.richmond.edu/physics-faculty-publicationsPart of the Nuclear CommonsRecommended CitationAnghinolfi, M., J. Ball, N. A. Baltzell, M. Battaglieri, I. Bedlinskiy, M. Bellis, A. S. Biselli, C. Bookwalter, S. Boiarinov, P. Bosted, V. D.Burkert, D. S. Carman, A. Celentano, S. Chandavar, P. L. Cole, V. Crede, R. De Vita, E. De Sanctis, B. Dey, R. Dickson, D. Doughty, M.Dugger, R. Dupre, H. Egiyan, A. El Alaoui, L. El Fassi, L. Elouadrhiri, P. Eugenio, G. Fedotov, M. Y. Gabrielyan, M. Garcon, G. P.Gilfoyle, K. L. Giovanetti, F. X. Girod, J. T. Goetz, E. Golovatch, M. Guidal, L. Guo, K. Hafidi, H. Hakobyan, D. Heddle, K. Hicks, M.Holtrop, D. G. Ireland, B. S. Ishkhanov, E. L. Isupov, H. S. Jo, P. Khetarpal, A. Kim, W. Kim, V. Kubarovsky, S. V. Kuleshov, H. Y. Lu, I. J.D. MacGregor, N. Markov, M. E. Mccracken, B. McKinnon, M. D. Mestayer, C. A. Meyer, M. Mirazita, V. Mokeev, K. Moriya, B.Morrison, A. Ni, S. Niccolai, G. Niculescu, I. Niculescu, M. Osipenko, A. I. Ostrovidov, K. Park, S. Park, S. Anefalos Pereira, S. Pisano,O. Pogorelko, S. Pozdniakov, J. W. Price, G. Ricco, M. Ripani, B. G. Ritchie, P. Rossi, D. Schott, R. A. Schumacher, E. Seder, Y. G.Sharabian, E. S. Smith, D. I. Sober, S. S. Stepanyan, P. Stoler, W. Tang, M. Ungaro, B. Vernarsky, M. F. Vineyard, D. P. Weygand, M. H.Wood, N. Zachariou, and B. Zhao. "Comment on “Observation of a Narrow Structure in 1H(γ,KS0)X Via Interference with ϕ-MesonProduction”." Physical Review C 86, no. 6 (2012): 069801:1-3. doi:10.1103/PhysRevC.86.069801.PHYSICAL REVIEW C 86, 069801 (2012)Comment on “Observation of a narrow structure in 1H(γ ,K 0S)X via interferencewith φ-meson production”M. Anghinolfi,18 J. Ball,8 N. A. Baltzell,1,29 M. Battaglieri,18 I. Bedlinskiy,20 M. Bellis,6,25 A. S. Biselli,11 C. Bookwalter,13S. Boiarinov,20,30 P. Bosted,30 V. D. Burkert,30 D. S. Carman,30 A. Celentano,18 S. Chandavar,24 P. L. Cole,16,30 V. Crede,13R. De Vita,18 E. De Sanctis,17 B. Dey,6 R. Dickson,6 D. Doughty,9,30 M. Dugger,2 R. Dupre,1 H. Egiyan,30,35 A. El Alaoui,1L. El Fassi,1 L. Elouadrhiri,30 P. Eugenio,13 G. Fedotov,29 M. Y. Gabrielyan,12 M. Garcon,8 G. P. Gilfoyle,27 K. L. Giovanetti,21F. X. Girod,30 J. T. Goetz,3 E. Golovatch,28 M. Guidal,19 L. Guo,12,30 K. Hafidi,1 H. Hakobyan,32 D. Heddle,9,30 K. Hicks,24M. Holtrop,23 D. G. Ireland,33 B. S. Ishkhanov,28 E. L. Isupov,28 H. S. Jo,19 P. Khetarpal,12 A. Kim,22 W. Kim,22V. Kubarovsky,30 S. V. Kuleshov,20,32 H. Y. Lu,6 I. J. D. MacGregor,33 N. Markov,10 M. E. McCracken,6,34 B. McKinnon,33M. D. Mestayer,30 C. A. Meyer,6 M. Mirazita,17 V. Mokeev,28,30 K. Moriya,6,* B. Morrison,2 A. Ni,22 S. Niccolai,19G. Niculescu,21,24 I. Niculescu,15,21,30 M. Osipenko,18 A. I. Ostrovidov,13 K. Park,22,30 S. Park,13 S. Anefalos Pereira,17S. Pisano,17 O. Pogorelko,20 S. Pozdniakov,20 J. W. Price,4 G. Ricco,14 M. Ripani,18 B. G. Ritchie,2 P. Rossi,17 D. Schott,12R. A. Schumacher,6 E. Seder,10 Y. G. Sharabian,30 E. S. Smith,30 D. I. Sober,7 S. S. Stepanyan,22 P. Stoler,26 W. Tang,24M. Ungaro,10,26,30 B. Vernarsky,6 M. F. Vineyard,27,31 D. P. Weygand,30 M. H. Wood,5,29 N. Zachariou,15 and B. Zhao351Argonne National Laboratory, Argonne, Illinois 60439, USA2Arizona State University, Tempe, Arizona 85287-1504, USA3University of California at Los Angeles, Los Angeles, California 90095-1547, USA4California State University, Dominguez Hills, Carson, California 90747, USA5Canisius College, Buffalo, New York, USA6Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, USA7Catholic University of America, Washington, D.C. 20064, USA8CEA, Centre de Saclay, Irfu/Service de Physique Nucléaire, 91191 Gif-sur-Yvette, France9Christopher Newport University, Newport News, Virginia 23606, USA10University of Connecticut, Storrs, Connecticut 06269, USA11Fairfield University, Fairfield, Connecticut 06824, USA12Florida International University, Miami, Florida 33199, USA13Florida State University, Tallahassee, Florida 32306, ISA14Università di Genova, 16146 Genova, Italy15The George Washington University, Washington, D.C. 20052, USA16Idaho State University, Pocatello, Idaho 83209, USA17INFN, Laboratori Nazionali di Frascati, 00044 Frascati, Italy18INFN, Sezione di Genova, 16146 Genova, Italy19Institut de Physique Nucléaire ORSAY, Orsay, France20Institute of Theoretical and Experimental Physics, Moscow, 117259, Russia21James Madison University, Harrisonburg, Virginia 22807, USA22Kyungpook National University, Daegu 702-701, Republic of Korea23University of New Hampshire, Durham, New Hampshire 03824-3568, USA24Ohio University, Athens, Ohio 45701, USA25Northern Illinois University, Dekalb, Illinois 60115, USA26Rensselaer Polytechnic Institute, Troy, New York 12180-3590, USA27University of Richmond, Richmond, Virginia 23173, USA28Skobeltsyn Nuclear Physics Institute at Moscow State University, 119899 Moscow, Russia29University of South Carolina, Columbia, South Carolina 29208, USA30Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606, USA31Union College, Schenectady, New York 12308, USA32Universidad Técnica Federico Santa Marı́a, Casilla 110-V Valparaı́so, Chile33University of Glasgow, Glasgow G12 8QQ, United Kingdom34Washington & Jefferson College, Washington, Pennsylvania 15301, USA35College of William and Mary, Williamsburg, Virginia 23187-8795, USA(Received 9 April 2012; published 6 December 2012)DOI: 10.1103/PhysRevC.86.069801 PACS number(s): 13.60.Rj, 14.40.−n, 24.85.+p, 25.20.Lj*Current address: Indiana University, Bloomington, IN 47405.In Ref. [1], the authors claim to observe a narrow structurein themass spectrum constructed from the (pKL) system usingdata from the CLAS detector. The interpretation of this narrowstructure given in Ref. [1] is as follows: “It may be due to the069801-10556-2813/2012/86(6)/069801(2) ©2012 American Physical SocietyCOMMENTS PHYSICAL REVIEW C 86, 069801 (2012)photoproduction of the + pentaquark or some unknown ∗resonance.” The authors go on to say that “it is unlikely for theobserved structure to be due to a ∗ resonance.”This analysis was reviewed by the CLAS Collaboration,following the established procedures for all CLAS papers, anddid not receive approval. The purpose of this Comment is toexplain the reasons why that analysis was not approved forpublication.An extensive review of the analysis in Ref. [1] was carriedout by two separate committees of the Hadron SpectroscopyPhysics Working Group in the CLAS Collaboration. In bothcases, the committees came to the same conclusion: Thephysics claims of Ref. [1] could not be supported. The reasonsfor this conclusion are manyfold, but a primary concern is thelack of justification for the kinematic cuts used in that analysis.The review committees reported that the narrow structureappears only within a specific range of values of the kinematiccuts. Here, the details are important (which cuts were variedand by how much) but this would require more space todocument than a simple Comment will allow. We give onlyone example below but note that the CLAS committeesconducted an extensive review of the sensitivity of the narrowstructure to what they considered reasonable variations of thecuts [2].As an example, the cut on the t variable (defined inRef. [1])was restricted to a small region of the total phase space(−t < 0.45 GeV2). Without this cut, the narrow structure isnot statistically significant. By examining Fig. 8 of Ref. [1],one can see that the structure is not really visible in the topspectrum [Fig. 8(a)] and appears only in Fig. 8(c). When thecut value is increased by 20% (−t < 0.55) as shown byFig. 8(b), or decreased by 10% (t < 0.4), as shown byFig. 8(d), then the purported structure at a mass of 1.54 GeVis consistent in size with other fluctuations in those spectra.While the authors of Ref. [1] make an argument aboutwhy the t cut was necessary, the CLAS Collaboration wasnot convinced. For example, it is possible that an interferencebetween the narrow structure and the background is dependenton the t variable, but this assumption is difficult to prove. Theanalysis ofRef. [1] did not provide any evidence of interferencephases.It is not uncommon to use kinematic cuts to reducebackground and, hence, improve the signal-to-backgroundratio for known particles, but other studies [3] have shownthat one must be careful when applying kinematic cuts thatcan create spurious fluctuations. We could argue whether thekinematic cuts used inRef. [1] are justified, but the fact remainsthat the CLASCollaboration as awhole was not convinced thatthe narrow structure of Ref. [1] corresponds to a real physicalentity.In the end, the validity of the narrow structure claimed byRef. [1] will be determined by future experiments. If it is aphysical resonance, as suggested by Ref. [1], then it shouldbe reproducible. The evidence presented in Ref. [1] was notsufficient to convince the CLAS Collaboration of the physicsconclusions of that analysis.[1] M. Amaryan et al., Phys. Rev. C 85, 035209(2012).[2] E. Smith et al., Report of the committee to review theODU analysis of meson-baryon interference, version 3,CLAS-NOTE 2011-021 [https://misportal.jlab.org/ul/Physics/Hall-B/clas/].[3] J. Klein and A. Roodman, Ann. Rev. Nucl. Part. Sci. 55, 141(2005).069801-2

Comment on “Observation of a Narrow Structure in \u3csup\u3e1\u3c/sup\u3eH(γ,K\u3csub\u3eS\u3c/sub\u3e\u3csup\u3e0\u3c/sup\u3e)\u3cem\u3eX\u3c/em\u3e via Interference with \u3cem\u3eϕ\u3c/em\u3e-Meson Production”

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Comment on “Observation of a Narrow Structure in \u3csup\u3e1\u3c/sup\u3eH(γ,K\u3csub\u3eS\u3c/sub\u3e\u3csup\u3e0\u3c/sup\u3e)\u3cem\u3eX\u3c/em\u3e via Interference with \u3cem\u3eϕ\u3c/em\u3e-Meson Production”

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