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Search for a τ + τ - Resonance in e + e - → μ + μ - τ + τ - Events with the Belle II Experiment

Adachi, I.·Adamczyk, K. (ORCID:0000000162080876)·Aggarwal, L. (ORCID:0000000209097537)·Ahmed, H. (ORCID:0000000339767498)·Aihara, H. (ORCID:0000000219075964)·Akopov, N. (ORCID:0000000244252096)·Aloisio, A. (ORCID:0000000238836693)·Anh Ky, N. (ORCID:000000030471197X)·Asner, D. M. (ORCID:0000000215865790)·Atmacan, H. (ORCID:000000032435501X)·Aushev, T. (ORCID:0000000263477055)·Aushev, V. (ORCID:0000000285885308)·Aversano, M. (ORCID:0000000199800953)·Babu, V. (ORCID:0000000304196912)·Bae, H. (ORCID:0000000313938631)·Bahinipati, S. (ORCID:0000000237445332)·Bambade, P. (ORCID:0000000173784852)·Banerjee, Sw (ORCID:0000000188522409)·Bansal, S. (ORCID:0000000319920336)·Barrett, M. (ORCID:000000022095603X)·Baudot, J. (ORCID:0000000155850991)·Bauer, M. (ORCID:0000000209537387)·Baur, A. (ORCID:0000000313603292)·Beaubien, A. (ORCID:000000019438089X)·Becker, J. (ORCID:0000000250825487)·Behera, P. K. (ORCID:0000000215272266)·Bennett, J. V. (ORCID:0000000254402668)·Bernieri, E. (ORCID:0000000247872047)·Bernlochner, F. U. (ORCID:0000000181532719)·Bertacchi, V. (ORCID:0000000199711176)·Bertemes, M. (ORCID:000000015038360X)·Bertholet, E. (ORCID:0000000237922450)·Bessner, M. (ORCID:0000000317760439)·Bettarini, S. (ORCID:0000000177422998)·Bhardwaj, V. (ORCID:0000000188578621)·Bhuyan, B. (ORCID:0000000162543594)·Bianchi, F. (ORCID:0000000215246236)·Bilka, T. (ORCID:0000000314496986)·Bilokin, S. (ORCID:0000000300176260)·Biswas, D. (ORCID:0000000275433471)·Bobrov, A. (ORCID:0000000157358386)·Bodrov, D. (ORCID:0000000152794787)·Bolz, A. (ORCID:0000000240339223)·Borah, J. (ORCID:0000000329901913)·Bozek, A. (ORCID:0000000259151319)·Bračko, M. (ORCID:0000000224950524)·Branchini, P. (ORCID:0000000222709673)·Browder, T. E. (ORCID:0000000173579007)·Budano, A. (ORCID:0000000208561131)·Bussino, S. (ORCID:0000000238299592)·Campajola, M. (ORCID:0000000325187134)·Cao, L. (ORCID:0000000183325668)·Casarosa, G. (ORCID:000000034137938X)·Cecchi, C. (ORCID:0000000221928233)·Cerasoli, J. (ORCID:000000019777881X)·Chang, M. -C. (ORCID:0000000286506058)·Chang, P. (ORCID:000000034064388X)·Cheaib, R. (ORCID:0000000157298926)·Cheema, P. (ORCID:0000000184725727)·Chekelian, V. (ORCID:0000000188608288)·Chen, Y. Q. (ORCID:0000000272853251)·Cheon, B. G. (ORCID:0000000288034429)·Chilikin, K. (ORCID:0000000176202053)·Chirapatpimol, K. (ORCID:0000000320997760)·Cho, H. -E. (ORCID:0000000270083759)·Cho, K. (ORCID:0000000317057399)·Cho, S. -J. (ORCID:0000000216735664)·Choi, S. -K. (ORCID:0000000327478277)·Choudhury, S. (ORCID:0000000198410216)·Cinabro, D. (ORCID:0000000173476585)·Cochran, J. (ORCID:000000021492914X)·Corona, L. (ORCID:0000000225779909)·Cremaldi, L. M. (ORCID:0000000155507827)·Cunliffe, S. (ORCID:0000000301678641)·Czank, T. (ORCID:0000000166213373)·Das, S. (ORCID:000000016857966X)·Dattola, F. (ORCID:0000000333168574)·De La Cruz-Burelo, E. (ORCID:0000000274696974)·De La Motte, S. A. (ORCID:0000000339056805)·de Marino, G. (ORCID:0000000265097793)·De Nardo, G. (ORCID:0000000220479675)·De Nuccio, M. (ORCID:0000000209729047)·De Pietro, G. (ORCID:000000018442107X)·de Sangro, R. (ORCID:0000000238085455)·Destefanis, M. (ORCID:0000000319976751)·Dey, S. (ORCID:0000000329973829)·De Yta-Hernandez, A. (ORCID:0000000221627334)·Dhamija, R. (ORCID:0000000170523163)·Di Canto, A. (ORCID:0000000312333876)·Di Capua, F. (ORCID:0000000190765936)·Dingfelder, J. (ORCID:0000000157672121)·Doležal, Z. (ORCID:0000000256623675)·Domínguez Jiménez, I. (ORCID:0000000168313159)·Dong, T. V. (ORCID:0000000330431939)·Dorigo, M. (ORCID:0000000206816946)·Dort, K. (ORCID:0000000308498774)·Dossett, D. (ORCID:0000000256705582)·Dreyer, S. (ORCID:000000026295100X)·Dubey, S. (ORCID:0000000213450970)·Dujany, G. (ORCID:0000000213458163)
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Abstract

We report the first search for a nonstandard-model resonance decaying into $τ$ pairs in $e^+e^-$ → $μ^+μ^-τ^+τ^-$ events in the 3.6–10 GeV/c 2 mass range. We use a 62.8 fb -1 sample of $e^+e^-$ collisions collected at a center-of-mass energy of 10.58 GeV by the Belle II experiment at the SuperKEKB collider. The analysis probes three different models predicting a spin-1 particle coupling only to the heavier lepton families, a Higgs-like spin-0 particle that couples preferentially to charged leptons (leptophilic scalar), and an axionlike particle, respectively. We observe no evidence for a signal and set exclusion limits at 90% confidence level on the product of cross section and branching fraction into $τ$ pairs, ranging from 0.7 to 24 fb, and on the couplings of these processes. We obtain world-leading constraints on the couplings for the leptophilic scalar model for masses above 6.5 GeV/c 2 and for the axionlike particle model over the entire mass range.

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Adachi, I., Adamczyk, K. (ORCID:0000000162080876), Aggarwal, L. (ORCID:0000000209097537), Ahmed, H. (ORCID:0000000339767498), Aihara, H. (ORCID:0000000219075964), Akopov, N. (ORCID:0000000244252096), Aloisio, A. (ORCID:0000000238836693), Anh Ky, N. (ORCID:000000030471197X), Asner, D. M. (ORCID:0000000215865790), Atmacan, H. (ORCID:000000032435501X), Aushev, T. (ORCID:0000000263477055), Aushev, V. (ORCID:0000000285885308), Aversano, M. (ORCID:0000000199800953), Babu, V. (ORCID:0000000304196912), Bae, H. (ORCID:0000000313938631), Bahinipati, S. (ORCID:0000000237445332), Bambade, P. (ORCID:0000000173784852), Banerjee, Sw (ORCID:0000000188522409), Bansal, S. (ORCID:0000000319920336), Barrett, M. (ORCID:000000022095603X), Baudot, J. (ORCID:0000000155850991), Bauer, M. (ORCID:0000000209537387), Baur, A. (ORCID:0000000313603292), Beaubien, A. (ORCID:000000019438089X), Becker, J. (ORCID:0000000250825487), Behera, P. K. (ORCID:0000000215272266), Bennett, J. V. (ORCID:0000000254402668), Bernieri, E. (ORCID:0000000247872047), Bernlochner, F. U. (ORCID:0000000181532719), Bertacchi, V. (ORCID:0000000199711176), Bertemes, M. (ORCID:000000015038360X), Bertholet, E. (ORCID:0000000237922450), Bessner, M. (ORCID:0000000317760439), Bettarini, S. (ORCID:0000000177422998), Bhardwaj, V. (ORCID:0000000188578621), Bhuyan, B. (ORCID:0000000162543594), Bianchi, F. (ORCID:0000000215246236), Bilka, T. (ORCID:0000000314496986), Bilokin, S. (ORCID:0000000300176260), Biswas, D. (ORCID:0000000275433471), Bobrov, A. (ORCID:0000000157358386), Bodrov, D. (ORCID:0000000152794787), Bolz, A. (ORCID:0000000240339223), Borah, J. (ORCID:0000000329901913), Bozek, A. (ORCID:0000000259151319), Bračko, M. (ORCID:0000000224950524), Branchini, P. (ORCID:0000000222709673), Browder, T. E. (ORCID:0000000173579007), Budano, A. (ORCID:0000000208561131), Bussino, S. (ORCID:0000000238299592), Campajola, M. (ORCID:0000000325187134), Cao, L. (ORCID:0000000183325668), Casarosa, G. (ORCID:000000034137938X), Cecchi, C. (ORCID:0000000221928233), Cerasoli, J. (ORCID:000000019777881X), Chang, M. -C. (ORCID:0000000286506058), Chang, P. (ORCID:000000034064388X), Cheaib, R. (ORCID:0000000157298926), Cheema, P. (ORCID:0000000184725727), Chekelian, V. (ORCID:0000000188608288), Chen, Y. Q. (ORCID:0000000272853251), Cheon, B. G. (ORCID:0000000288034429), Chilikin, K. (ORCID:0000000176202053), Chirapatpimol, K. (ORCID:0000000320997760), Cho, H. -E. (ORCID:0000000270083759), Cho, K. (ORCID:0000000317057399), Cho, S. -J. (ORCID:0000000216735664), Choi, S. -K. (ORCID:0000000327478277), Choudhury, S. (ORCID:0000000198410216), Cinabro, D. (ORCID:0000000173476585), Cochran, J. (ORCID:000000021492914X), Corona, L. (ORCID:0000000225779909), Cremaldi, L. M. (ORCID:0000000155507827), Cunliffe, S. (ORCID:0000000301678641), Czank, T. (ORCID:0000000166213373), Das, S. (ORCID:000000016857966X), Dattola, F. (ORCID:0000000333168574), De La Cruz-Burelo, E. (ORCID:0000000274696974), De La Motte, S. A. (ORCID:0000000339056805), de Marino, G. (ORCID:0000000265097793), De Nardo, G. (ORCID:0000000220479675), De Nuccio, M. (ORCID:0000000209729047), De Pietro, G. (ORCID:000000018442107X), de Sangro, R. (ORCID:0000000238085455), Destefanis, M. (ORCID:0000000319976751), Dey, S. (ORCID:0000000329973829), De Yta-Hernandez, A. (ORCID:0000000221627334), Dhamija, R. (ORCID:0000000170523163), Di Canto, A. (ORCID:0000000312333876), Di Capua, F. (ORCID:0000000190765936), Dingfelder, J. (ORCID:0000000157672121), Doležal, Z. (ORCID:0000000256623675), Domínguez Jiménez, I. (ORCID:0000000168313159), Dong, T. V. (ORCID:0000000330431939), Dorigo, M. (ORCID:0000000206816946), Dort, K. (ORCID:0000000308498774), Dossett, D. (ORCID:0000000256705582), Dreyer, S. (ORCID:000000026295100X), Dubey, S. (ORCID:0000000213450970), Dujany, G. (ORCID:0000000213458163). 2023-09-21. Search for a τ + τ - Resonance in e + e - → μ + μ - τ + τ - Events with the Belle II Experiment. https://doi.org/10.1103/physrevlett.131.121802

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