Search for muoproduction of X(3872) at COMPASS and indication of a new state [formula omitted

M Aghasyan,P Sznajder,G Hamar,V Tskhay,F Krinner,N.S Rogacheva,K Kurek,J Ter Wolbeek,A Gridin,Ch Dreisbach,A.M Kotzinian,W Augustyniak,S Ramos,F Klein,B Grube,A Selyunin,J.-C Peng,E Seder,K Schmidt,O.P Gavrichtchouk,T Matsuda,K Bicker,H Schmieden,M Bodlak,Yu.A Khokhlov,A Cicuttin,D.I Ryabchikov,H Fischer,S Dalla Torre,S Sarkar,J Nový,R Birsa,T Sawada,A Nagaytsev,G Nukazuka,E Zemlyanichkina,D Panzieri,G Sbrizzai,P.D Eversheim,A Ferrero,M Ostrick,E Fuchey,R Beck,Yu.V Mikhailov,S Wallner,G Reicherz,M Meyer,M Pešková,G.K Mallot,A Thiel,J Pretz,R Heitz,M Chiosso,J Tomsa,A Guskov,A Vauth,M Pešek,G.V Khaustov,C Riedl,A Vidon,K Kondo,A Amoroso,Y Bedfer,C Regali,L Sinha,J.H Koivuniemi,P Kremser,S Huber,C Quintans,T Grussenmeyer,B Ketzer,V.A Polyakov,S Uhl,P Jörg,I Gnesi,M Ball,N Doshita,F Herrmann,A Magnon,A Szabelski,L Silva,M Wilfert,J Bernhard,T Weisrock,M Grosse Perdekamp,M Virius,R Salac,N Zhuravlev,M Faessler,R Akhunzyanov,M Krämer,F Tosello,S Levorato,M Stolarski,J Giarra,F Giordano,S Gerassimov,A Martin,D Von Harrach,A Srnka,N Makke,D Steffen,S Sirtl,K Augsten,F Tessarotto,F Nerling,A Maggiora,D Neyret,C Franco,C.-Y Hsieh,Y.-S Lian,C Santos,A Sandacz,E.R Bielert,M Levillain,N Du Fresne Von Hohenesche,W Dünnweber,F Pereira,F Bradamante,S Ishimoto,I Konorov,E Kabuß,P Schiavon,V Andrieux,C Chatterjee,N Horikawa,J Pochodzalla,M Finger,A Grasso,Z.V Kroumchtein,Yu Kisselev,Y Miyachi,D.V Peshekhonov,B Parsamyan,S Paul,O Subrt,A Rychter,F Balestra,L Dhara,R Joosten,A Austregesilo,A Bressan,V.E Burtsev,M.L Crespo,S Dasgupta,A.G Chumakov,S.V Donskov,B Badełek,M Ziembicki,K Schönning,S.A Mamon,A.A Lednev,F Gautheron,D Hahne,J Marzec,N Mitrofanov,W.-D Nowak,M Mikhasenko,M Quaresma,E.A Levchenko,S Tessaro,M Dziewiecki,M Zavertyaev,M Gorzellik,A Antoshkin,V.N Kolosov,P Bordalo,J Lichtenstadt,A Kveton,J Barth,V.D Samoylenko,A Efremov,E Mitrofanov,Yu Ivanshin,T Szameitat,N Pierre,C.D.R Azevedo,M Büchele,F Kunne,S Platchkov,N Makins,A Kerbizi,K Königsmann,B Mariański ,A S Nunes ,V Jarý ,Y P Kulinich ,К Заремба ,Zdeněk Král ,G Meshcheryakov ,Hiroki Matsuda ,И Орлов ,Jan Matoušek ,G D Alexeev ,А Иванов ,А.g Оlshevsky ,P Závada ,В.ф Константинов ,O Kouznetsov ,M Alexeev ,M Slunečka ,Riccardo Longo ,M Taševský ,I J Choi ,Valery E Lyubovitskij ,M Šulc ,V V Frolov ,R R Dusaev ,Hiromasa Suzuki ,S U Chung ,Jan Friedrich ,J Smolík ,N D’hose ,W T Meyer ,I Savin ,F H Heinsius ,Ivan Kuznetsov ,B I Vasilishin ,W C Chang ,В Аносов ,Н Анфимов ,R Kurjata ,А Рыбников ,Tadahisa Iwata ,J.f.c.a Veloso ,О Денисов

doi:10.1016/j.physletb.2018.07.008

Abstract

We have searched for exclusive production of exotic charmonia in the reaction μ+N→μ+(J/ψπ+π−)π±N′ using COMPASS data collected with incoming muons of 160 GeV/c and 200 GeV/c momentum. In the J/ψπ+π− mass distribution we observe a signal with a statistical significance of 4.1 σ. Its mass and width are consistent with those of the X(3872). The shape of the π+π− mass distribution from the observed decay into J/ψπ+π− shows disagreement with previous observations for X(3872). The observed signal may be interpreted as a possible evidence of a new charmonium state. It could be associated with a neutral partner of X(3872) with C=−1 predicted by a tetraquark model. The product of cross section and branching fraction of the decay of the observed state into J/ψπ+π− is determined to be 71±28(stat)±39(syst) pb.

Highlights

We have searched for exclusive production of exotic charmonia in the reaction μ+ N → μ+( J/ψπ +π −)π ± N
The observed signal may be interpreted as a possible evidence of a new charmonium state
It could be associated with a neutral partner of X(3872) with C = −1 predicted by a tetraquark model

Summary

Contents lists available at ScienceDirect

Search for muoproduction of X(3872) at COMPASS and indication of a new state X(3872). Since the dimuon mass resolution of the setup for the J /ψ peak is about 50 MeV/c2 [35], candidates for J /ψ decaying into a pair of oppositely charged muons are accepted if their reconstructed mass lies in the range from 3.02 GeV/c2 to 3.18 GeV/c2. Since at COMPASS the experimental resolution for E = E − Ebeam is about 2 GeV, we require | E| < 4 GeV in order to select exclusive production of the J /ψ3π final state.

The upper limit

The cross range of

Findings

COMPASS Collaboration