The first observation of the concurrent production of two J/$psi$ mesons in proton-nucleus collisions is presented. The analysis is based on a proton-lead (pPb) data sample recorded at a nucleon-nucleon center-of-mass energy of 8.16 TeV by the CMS experiment at the CERN LHC and corresponding to an integrated luminosity of 174.6 nb$^{-1}$. The two J/$psi$ mesons are reconstructed in their $mu^+mu^-$ decay channels with transverse momenta $p_mathrm{T}$ $gt$ 6.5 GeV and rapidity $lvert y rvert$ $lt$ 2.4. Events where one of the J/$psi$ mesons is reconstructed in the dielectron channel are also considered in the search. The pPb $to$ J/$psi$J/$psi$+X process is observed with a significance of 5.3 standard deviations. The measured inclusive fiducial cross section, using the four-muon channel alone, is $sigma$(pPb$to$ J/$psi$J/$psi$+X)= 22.0 $pm$ 8.9 (stat) $pm$ 1.5 (syst) nb. A fit of the data to the expected rapidity separation for pairs of J/$psi$ mesons produced in single (SPS) and double (DPS) parton scatterings yields $sigma^{mathrm{pPb}tomathrm{J}/psimathrm{J}/psi+mathrm{X}}_text{SPS}$ = 16.5 $pm$ 10.8 (stat) $pm$ 0.1 (syst) nb and $sigma^{mathrm{pPb}to mathrm{J}/psimathrm{J}/psi+mathrm{X}}_text{DPS}$ = 5.4 $pm$ 6.2 (stat) $pm$ 0.4 (syst) nb, respectively. This latter result can be transformed into a lower bound on the effective DPS cross section, closely related to the squared average interparton transverse separation in the collision, of $sigma_text{eff}$ $gt$ 1.0 mb at 95% confidence level.
{"title":"Observation of double J/$ψ$ meson production in pPb collisions at $sqrt{s_mathrm{NN}}$ = 8.16 TeV","authors":"CMS Collaboration","doi":"arxiv-2407.03223","DOIUrl":"https://doi.org/arxiv-2407.03223","url":null,"abstract":"The first observation of the concurrent production of two J/$psi$ mesons in\u0000proton-nucleus collisions is presented. The analysis is based on a proton-lead\u0000(pPb) data sample recorded at a nucleon-nucleon center-of-mass energy of 8.16\u0000TeV by the CMS experiment at the CERN LHC and corresponding to an integrated\u0000luminosity of 174.6 nb$^{-1}$. The two J/$psi$ mesons are reconstructed in\u0000their $mu^+mu^-$ decay channels with transverse momenta $p_mathrm{T}$ $gt$\u00006.5 GeV and rapidity $lvert y rvert$ $lt$ 2.4. Events where one of the\u0000J/$psi$ mesons is reconstructed in the dielectron channel are also considered\u0000in the search. The pPb $to$ J/$psi$J/$psi$+X process is observed with a\u0000significance of 5.3 standard deviations. The measured inclusive fiducial cross\u0000section, using the four-muon channel alone, is $sigma$(pPb$to$\u0000J/$psi$J/$psi$+X)= 22.0 $pm$ 8.9 (stat) $pm$ 1.5 (syst) nb. A fit of the\u0000data to the expected rapidity separation for pairs of J/$psi$ mesons produced\u0000in single (SPS) and double (DPS) parton scatterings yields\u0000$sigma^{mathrm{pPb}tomathrm{J}/psimathrm{J}/psi+mathrm{X}}_text{SPS}$\u0000= 16.5 $pm$ 10.8 (stat) $pm$ 0.1 (syst) nb and $sigma^{mathrm{pPb}to\u0000mathrm{J}/psimathrm{J}/psi+mathrm{X}}_text{DPS}$ = 5.4 $pm$ 6.2 (stat)\u0000$pm$ 0.4 (syst) nb, respectively. This latter result can be transformed into a\u0000lower bound on the effective DPS cross section, closely related to the squared\u0000average interparton transverse separation in the collision, of\u0000$sigma_text{eff}$ $gt$ 1.0 mb at 95% confidence level.","PeriodicalId":501206,"journal":{"name":"arXiv - PHYS - Nuclear Experiment","volume":"13 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141550212","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
F. Afzal, C. S. Akondi, M. Albrecht, M. Amaryan, S. Arrigo, V. Arroyave, A. Asaturyan, A. Austregesilo, Z. Baldwin, F. Barbosa, J. Barlow, E. Barriga, R. Barsotti, D. Barton, V. Baturin, V. V. Berdnikov, T. Black, W. Boeglin, M. Boer, W. J. Briscoe, T. Britton, S. Cao, E. Chudakov, G. Chung, P. L. Cole, O. Cortes, V. Crede, M. M. Dalton, D. Darulis, A. Deur, S. Dobbs, A. Dolgolenko, M. Dugger, R. Dzhygadlo, D. Ebersole, M. Edo, H. Egiyan, T. Erbora, P. Eugenio, A. Fabrizi, C. Fanelli, S. Fang, J. Fitches, A. M. Foda, S. Furletov, L. Gan, H. Gao, A. Gardner, A. Gasparian, D. Glazier, C. Gleason, V. S. Goryachev, B. Grube, J. Guo, L. Guo, J. Hernandez, K. Hernandez, N. D. Hoffman, D. Hornidge, G. Hou, P. Hurck, A. Hurley, W. Imoehl, D. G. Ireland, M. M. Ito, I. Jaegle, N. S. Jarvis, T. Jeske, M. Jing, R. T. Jones, V. Kakoyan, G. Kalicy, V. Khachatryan, C. Kourkoumelis, A. LaDuke, I. Larin, D. Lawrence, D. I. Lersch, H. Li, B. Liu, K. Livingston, G. J. Lolos, L. Lorenti, V. Lyubovitskij, R. Ma, D. Mack, A. Mahmood, H. Marukyan, V. Matveev, M. McCaughan, M. McCracken, C. A. Meyer, R. Miskimen, R. E. Mitchell, K. Mizutani, V. Neelamana, L. Ng, E. Nissen, S. Orešić, A. I. Ostrovidov, Z. Papandreou, C. Paudel, R. Pedroni, L. Pentchev, K. J. Peters, E. Prather, S. Rakshit, J. Reinhold, A. Remington, B. G. Ritchie, J. Ritman, G. Rodriguez, D. Romanov, K. Saldana, C. Salgado, S. Schadmand, A. M. Schertz, K. Scheuer, A. Schick, A. Schmidt, R. A. Schumacher, J. Schwiening, N. Septian, P. Sharp, X. Shen, M. R. Shepherd, J. Sikes, A. Smith, E. S. Smith, D. I. Sober, A. Somov, S. Somov, J. R. Stevens, I. I. Strakovsky, B. Sumner, K. Suresh, V. V. Tarasov, S. Taylor, A. Teymurazyan, A. Thiel, T. Viducic, T. Whitlatch, N. Wickramaarachchi, Y. Wunderlich, B. Yu, J. Zarling, Z. Zhang, X. Zhou, B. Zihlmann
The spin-exotic hybrid meson $pi_{1}(1600)$ is predicted to have a large decay rate to the $omegapipi$ final state. Using 76.6~pb$^{-1}$ of data collected with the GlueX detector, we measure the cross sections for the reactions $gamma p to omega pi^+ pi^- p$, $gamma p to omega pi^0 pi^0 p$, and $gamma ptoomegapi^-pi^0Delta^{++}$ in the range $E_gamma =$ 8-10 GeV. Using isospin conservation, we set the first upper limits on the photoproduction cross sections of the $pi^{0}_{1}(1600)$ and $pi^{-}_{1}(1600)$. We combine these limits with lattice calculations of decay widths and find that photoproduction of $eta'pi$ is the most sensitive two-body system to search for the $pi_1(1600)$.
据预测，自旋外杂介子$pi_{1}(1600)$到$omegapipi$终态的衰变率很大。利用 76.6~pb$^{-1}$ 的数据，我们测量了 $gamma p to omega pi^+ pi^- p$、$gamma p to omega pi^0 pi^0p$ 和 $gamma p toomegapi^-pi^0Delta^{++}$ 在 $E_gamma =$ 8-10GeV 范围内的作用截面。利用等空间守恒，我们首次设定了$pi^{0}_{1}(1600)$ 和$pi^{-}_{1}(1600)$ 的光生成截面上限。我们把这些极限与衰变宽度的晶格计算结合起来，发现$eta'pi$的光生成是寻找$pi_1(1600)$的最敏感的二体系统。
{"title":"An Upper Limit on the Photoproduction Cross Section of the Spin-Exotic $π_1(1600)$","authors":"F. Afzal, C. S. Akondi, M. Albrecht, M. Amaryan, S. Arrigo, V. Arroyave, A. Asaturyan, A. Austregesilo, Z. Baldwin, F. Barbosa, J. Barlow, E. Barriga, R. Barsotti, D. Barton, V. Baturin, V. V. Berdnikov, T. Black, W. Boeglin, M. Boer, W. J. Briscoe, T. Britton, S. Cao, E. Chudakov, G. Chung, P. L. Cole, O. Cortes, V. Crede, M. M. Dalton, D. Darulis, A. Deur, S. Dobbs, A. Dolgolenko, M. Dugger, R. Dzhygadlo, D. Ebersole, M. Edo, H. Egiyan, T. Erbora, P. Eugenio, A. Fabrizi, C. Fanelli, S. Fang, J. Fitches, A. M. Foda, S. Furletov, L. Gan, H. Gao, A. Gardner, A. Gasparian, D. Glazier, C. Gleason, V. S. Goryachev, B. Grube, J. Guo, L. Guo, J. Hernandez, K. Hernandez, N. D. Hoffman, D. Hornidge, G. Hou, P. Hurck, A. Hurley, W. Imoehl, D. G. Ireland, M. M. Ito, I. Jaegle, N. S. Jarvis, T. Jeske, M. Jing, R. T. Jones, V. Kakoyan, G. Kalicy, V. Khachatryan, C. Kourkoumelis, A. LaDuke, I. Larin, D. Lawrence, D. I. Lersch, H. Li, B. Liu, K. Livingston, G. J. Lolos, L. Lorenti, V. Lyubovitskij, R. Ma, D. Mack, A. Mahmood, H. Marukyan, V. Matveev, M. McCaughan, M. McCracken, C. A. Meyer, R. Miskimen, R. E. Mitchell, K. Mizutani, V. Neelamana, L. Ng, E. Nissen, S. Orešić, A. I. Ostrovidov, Z. Papandreou, C. Paudel, R. Pedroni, L. Pentchev, K. J. Peters, E. Prather, S. Rakshit, J. Reinhold, A. Remington, B. G. Ritchie, J. Ritman, G. Rodriguez, D. Romanov, K. Saldana, C. Salgado, S. Schadmand, A. M. Schertz, K. Scheuer, A. Schick, A. Schmidt, R. A. Schumacher, J. Schwiening, N. Septian, P. Sharp, X. Shen, M. R. Shepherd, J. Sikes, A. Smith, E. S. Smith, D. I. Sober, A. Somov, S. Somov, J. R. Stevens, I. I. Strakovsky, B. Sumner, K. Suresh, V. V. Tarasov, S. Taylor, A. Teymurazyan, A. Thiel, T. Viducic, T. Whitlatch, N. Wickramaarachchi, Y. Wunderlich, B. Yu, J. Zarling, Z. Zhang, X. Zhou, B. Zihlmann","doi":"arxiv-2407.03316","DOIUrl":"https://doi.org/arxiv-2407.03316","url":null,"abstract":"The spin-exotic hybrid meson $pi_{1}(1600)$ is predicted to have a large\u0000decay rate to the $omegapipi$ final state. Using 76.6~pb$^{-1}$ of data\u0000collected with the GlueX detector, we measure the cross sections for the\u0000reactions $gamma p to omega pi^+ pi^- p$, $gamma p to omega pi^0 pi^0\u0000p$, and $gamma ptoomegapi^-pi^0Delta^{++}$ in the range $E_gamma =$ 8-10\u0000GeV. Using isospin conservation, we set the first upper limits on the\u0000photoproduction cross sections of the $pi^{0}_{1}(1600)$ and\u0000$pi^{-}_{1}(1600)$. We combine these limits with lattice calculations of decay\u0000widths and find that photoproduction of $eta'pi$ is the most sensitive\u0000two-body system to search for the $pi_1(1600)$.","PeriodicalId":501206,"journal":{"name":"arXiv - PHYS - Nuclear Experiment","volume":"49 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141550211","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The PHENIX experiment at RHIC has a unique large rapidity coverage ($1.2 < |y| < 2.2$) for heavy flavor studies in heavy-ion collisions. This kinematic region has a smaller particle density and may undergo different nuclear effects before and after the hard process when compared to mid-rapidity production. The latest PHENIX runs contain a large data set which allows, for the first time, the study of heavy flavor and $J/psi$ flow at the large rapidity region in Au$+$Au collisions at $sqrt{s_{_{NN}}}=$200 GeV. This measurement has the potential to reveal a medium evolution distinct from that known at mid-rapidity.
{"title":"Heavy Flavor and Quarkonia Results from the PHENIX Experiment","authors":"Krista Smith","doi":"arxiv-2407.02451","DOIUrl":"https://doi.org/arxiv-2407.02451","url":null,"abstract":"The PHENIX experiment at RHIC has a unique large rapidity coverage ($1.2 <\u0000|y| < 2.2$) for heavy flavor studies in heavy-ion collisions. This kinematic\u0000region has a smaller particle density and may undergo different nuclear effects\u0000before and after the hard process when compared to mid-rapidity production. The\u0000latest PHENIX runs contain a large data set which allows, for the first time,\u0000the study of heavy flavor and $J/psi$ flow at the large rapidity region in\u0000Au$+$Au collisions at $sqrt{s_{_{NN}}}=$200 GeV. This measurement has the\u0000potential to reveal a medium evolution distinct from that known at\u0000mid-rapidity.","PeriodicalId":501206,"journal":{"name":"arXiv - PHYS - Nuclear Experiment","volume":"43 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141521028","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The production cross section of inclusive isolated photons has been measured by the ALICE experiment at the CERN LHC in pp collisions at centre-of-momentum energy of $sqrt{s}=13$ TeV collected during the LHC Run 2 data-taking period. The measurement is performed by combining the measurements of the electromagnetic calorimeter EMCal and the central tracking detectors ITS and TPC, covering a pseudorapidity range of $|eta^{gamma}|<0.67$ and a transverse momentum range of $7
{"title":"Measurement of the inclusive isolated-photon production cross section in pp collisions at $sqrt{s}$ = 13 TeV","authors":"ALICE Collaboration","doi":"arxiv-2407.01165","DOIUrl":"https://doi.org/arxiv-2407.01165","url":null,"abstract":"The production cross section of inclusive isolated photons has been measured\u0000by the ALICE experiment at the CERN LHC in pp collisions at centre-of-momentum\u0000energy of $sqrt{s}=13$ TeV collected during the LHC Run 2 data-taking period.\u0000The measurement is performed by combining the measurements of the\u0000electromagnetic calorimeter EMCal and the central tracking detectors ITS and\u0000TPC, covering a pseudorapidity range of $|eta^{gamma}|<0.67$ and a transverse\u0000momentum range of $7<p_{rm T}^{gamma}<200$ GeV/$c$. The result extends to\u0000lower $p_{rm T}^{gamma}$ and $x_{rm T}^{gamma} = 2p_{rm\u0000T}^{gamma}/sqrt{s}$ ranges, the lowest $x_{rm T}^{gamma}$ of any isolated\u0000photon measurements to date, extending significantly those measured by the\u0000ATLAS and CMS experiments towards lower $p_{rm T}^{gamma}$ at the same\u0000collision energy with a small overlap between the measurements. The measurement\u0000is compared with next-to-leading order perturbative QCD calculations and the\u0000results from the ATLAS and CMS experiments as well as with measurements at\u0000other collision energies. The measurement and theory prediction are in\u0000agreement with each other within the experimental and theoretical\u0000uncertainties.","PeriodicalId":501206,"journal":{"name":"arXiv - PHYS - Nuclear Experiment","volume":"49 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141529735","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
P. Belli, R. Bernabei, F. Cappella, V. Caracciolo, R. Cerulli, F. A. Danevich, V. Yu. Denisov, A. Incicchitti, D. V. Kasperovych, V. V. Kobychev, G. P. Kovtun, M. Laubenstein, D. V. Poda, O. G. Polischuk, A. P. Shcherban, D. A. Solopikhin, S. Tessalina, V. I. Tretyak
A long-term measurement was conducted to search for $alpha$, double-$alpha$ and double-$beta$ decays with $gamma$ quanta emission in naturally occurring osmium isotopes. This study took advantage of two ultra-low background HPGe detectors and one ultra-low background BEGe detector at the Gran Sasso National Laboratory (LNGS) of the INFN. Over almost 5 years of data were taken using high-purity osmium samples of approximately 173 g. The half-life limits set for a decays of $^{184}$Os to the first $2^+$ 103.6 keV excited level of $^{180}$W ($T_{1/2} > 9.3 times 10^{15}$ yr) and of $^{186}$Os to the first $2^+$ 100.1 keV of $^{182}$W ($T_{1/2} > 4.8 times 10^{17}$ yr) exceed substantially the present theoretical predictions that are at level of $T_{1/2} sim (0.6 - 3) times 10^{15}$ yr for $^{184}$Os and $T_{1/2} sim (0.3 - 2) times 10^{17}$ yr for $^{186}$Os. New half-life limits on the 2EC and EC$beta^+$ decay of $^{184}$Os to the ground and excited levels of $^{184}$W were set at level of $T_{1/2} > 10^{16} - 10^{17}$ yr; a lower limit on the $2beta^-$ decay of $^{192}$Os to the $2^+$ 316.5 keV excited level of $^{192}$Pt was estimated as $T_{1/2} > 6.1 times 10^{20}$ yr. The half-life limits for $2alpha$ decay of $^{189}$Os and $^{192}$Os were set for the first time at level of $T_{1/2} > 10^{20}$ yr.
{"title":"Final results of the measurement to search for rare decays of naturally occurring osmium isotopes with ultra-low background gamma-ray spectrometry","authors":"P. Belli, R. Bernabei, F. Cappella, V. Caracciolo, R. Cerulli, F. A. Danevich, V. Yu. Denisov, A. Incicchitti, D. V. Kasperovych, V. V. Kobychev, G. P. Kovtun, M. Laubenstein, D. V. Poda, O. G. Polischuk, A. P. Shcherban, D. A. Solopikhin, S. Tessalina, V. I. Tretyak","doi":"arxiv-2406.19062","DOIUrl":"https://doi.org/arxiv-2406.19062","url":null,"abstract":"A long-term measurement was conducted to search for $alpha$, double-$alpha$\u0000and double-$beta$ decays with $gamma$ quanta emission in naturally occurring\u0000osmium isotopes. This study took advantage of two ultra-low background HPGe\u0000detectors and one ultra-low background BEGe detector at the Gran Sasso National\u0000Laboratory (LNGS) of the INFN. Over almost 5 years of data were taken using\u0000high-purity osmium samples of approximately 173 g. The half-life limits set for\u0000a decays of $^{184}$Os to the first $2^+$ 103.6 keV excited level of $^{180}$W\u0000($T_{1/2} > 9.3 times 10^{15}$ yr) and of $^{186}$Os to the first $2^+$ 100.1\u0000keV of $^{182}$W ($T_{1/2} > 4.8 times 10^{17}$ yr) exceed substantially the\u0000present theoretical predictions that are at level of $T_{1/2} sim (0.6 - 3)\u0000times 10^{15}$ yr for $^{184}$Os and $T_{1/2} sim (0.3 - 2) times 10^{17}$\u0000yr for $^{186}$Os. New half-life limits on the 2EC and EC$beta^+$ decay of\u0000$^{184}$Os to the ground and excited levels of $^{184}$W were set at level of\u0000$T_{1/2} > 10^{16} - 10^{17}$ yr; a lower limit on the $2beta^-$ decay of\u0000$^{192}$Os to the $2^+$ 316.5 keV excited level of $^{192}$Pt was estimated as\u0000$T_{1/2} > 6.1 times 10^{20}$ yr. The half-life limits for $2alpha$ decay of\u0000$^{189}$Os and $^{192}$Os were set for the first time at level of $T_{1/2} >\u000010^{20}$ yr.","PeriodicalId":501206,"journal":{"name":"arXiv - PHYS - Nuclear Experiment","volume":"27 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141507883","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
R. Bailhache, D. Bonocore, P. Braun-Munzinger, X. Feal, S. Floerchinger, J. Klein, K. Köhler, P. Lebiedowicz, C. M. Peter, R. Rapp, K. Reygers, W. Schäfer, H. S. Scheid, K. Schweda, J. Stachel, H. van Hees, C. A. van Veen, M. Völkl
This report summarizes the work of the EMMI Rapid Reaction Task Force on "Real and Virtual Photon Production at Ultra-Low Transverse Momentum and Low Mass at the LHC". We provide an overview of the soft-photon puzzle, i.e., of the long-standing discrepancy between experimental data and predictions based on Low's soft-photon theorem, also referred to as "anomalous" soft photon production, and we review the current theoretical understanding of soft radiation and soft theorems. We also focus on low-mass dileptons as a tool for determining the electrical conductivity of the medium produced in high-energy nucleus-nucleus collisions. We discuss how both topics can be addressed with the planned ALICE 3 detector at the LHC.
本报告总结了欧洲粒子监测中心 "大型强子对撞机超低横动量和低质量下的真实和虚拟光子产生 "快速反应工作组的工作。我们概述了软光子之谜，即实验数据与基于洛氏软光子定理（也称为 "反常 "软光子产生）的预测之间长期存在的差异，并回顾了当前对软辐射和软定理的理论理解。我们还关注低质量二价子，将其作为确定高能核-核碰撞中产生的介质导电性的工具。我们将讨论如何利用计划中的大型强子对撞机 ALICE 3 探测器来解决这两个问题。
{"title":"Anomalous soft photons: status and perspectives","authors":"R. Bailhache, D. Bonocore, P. Braun-Munzinger, X. Feal, S. Floerchinger, J. Klein, K. Köhler, P. Lebiedowicz, C. M. Peter, R. Rapp, K. Reygers, W. Schäfer, H. S. Scheid, K. Schweda, J. Stachel, H. van Hees, C. A. van Veen, M. Völkl","doi":"arxiv-2406.17959","DOIUrl":"https://doi.org/arxiv-2406.17959","url":null,"abstract":"This report summarizes the work of the EMMI Rapid Reaction Task Force on\u0000\"Real and Virtual Photon Production at Ultra-Low Transverse Momentum and Low\u0000Mass at the LHC\". We provide an overview of the soft-photon puzzle, i.e., of\u0000the long-standing discrepancy between experimental data and predictions based\u0000on Low's soft-photon theorem, also referred to as \"anomalous\" soft photon\u0000production, and we review the current theoretical understanding of soft\u0000radiation and soft theorems. We also focus on low-mass dileptons as a tool for\u0000determining the electrical conductivity of the medium produced in high-energy\u0000nucleus-nucleus collisions. We discuss how both topics can be addressed with\u0000the planned ALICE 3 detector at the LHC.","PeriodicalId":501206,"journal":{"name":"arXiv - PHYS - Nuclear Experiment","volume":"10 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-06-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141531540","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
R. N. Sahoo, M. Paul, Y. Kashiv, M. Tessler, M. Friedman, S. Halfon, A. Kreisel, A. Shor, L. Weissman
Stellar abundances of cerium are of high current interest based both on observations and theoretical models, especially with regard to the neutron--magic $^{140}$Ce isotope. A large discrepancy of $s-$process stellar models relative to cerium abundance observed in globular clusters was highlighted, pointing to possible uncertainties in experimental nuclear reaction rates. In this work, the stellar neutron capture cross section of the stable cerium isotopes $^{136}$Ce, $^{138}$Ce, $^{140}$Ce, and $^{142}$Ce, were re-measured. A $^{nat}$Ce sample was irradiated with quasi-Maxwellian neutrons at $kT = 34.2$ keV using the $^{7}$Li($p,n$) reaction. The neutron field with an intensity of $3-5 times 10^{10}$ n/s was produced by irradiating the liquid-lithium target (LiLiT) with a mA proton beam at an energy (1.92 MeV) just above the threshold at Soreq Applied Research Accelerator Facility (SARAF). The activities of the $^{nat}$Ce neutron capture products were measured using a shielded High Purity Germanium detector. Cross sections were extracted relative to that of the $^{197}$Au(n,$gamma$) reaction and the Maxwellian-averaged cross section (MACS) of the Ce isotopes were derived. The MACS values extracted from this experiment are generally consistent with previous measurements and show for $^{140}$Ce a value $approx 15$% smaller than most recent experimental values.
{"title":"Stellar s-process neutron capture cross section of Ce isotopes","authors":"R. N. Sahoo, M. Paul, Y. Kashiv, M. Tessler, M. Friedman, S. Halfon, A. Kreisel, A. Shor, L. Weissman","doi":"arxiv-2406.17646","DOIUrl":"https://doi.org/arxiv-2406.17646","url":null,"abstract":"Stellar abundances of cerium are of high current interest based both on\u0000observations and theoretical models, especially with regard to the\u0000neutron--magic $^{140}$Ce isotope. A large discrepancy of $s-$process stellar\u0000models relative to cerium abundance observed in globular clusters was\u0000highlighted, pointing to possible uncertainties in experimental nuclear\u0000reaction rates. In this work, the stellar neutron capture cross section of the\u0000stable cerium isotopes $^{136}$Ce, $^{138}$Ce, $^{140}$Ce, and $^{142}$Ce, were\u0000re-measured. A $^{nat}$Ce sample was irradiated with quasi-Maxwellian neutrons\u0000at $kT = 34.2$ keV using the $^{7}$Li($p,n$) reaction. The neutron field with\u0000an intensity of $3-5 times 10^{10}$ n/s was produced by irradiating the\u0000liquid-lithium target (LiLiT) with a mA proton beam at an energy (1.92 MeV)\u0000just above the threshold at Soreq Applied Research Accelerator Facility\u0000(SARAF). The activities of the $^{nat}$Ce neutron capture products were\u0000measured using a shielded High Purity Germanium detector. Cross sections were\u0000extracted relative to that of the $^{197}$Au(n,$gamma$) reaction and the\u0000Maxwellian-averaged cross section (MACS) of the Ce isotopes were derived. The\u0000MACS values extracted from this experiment are generally consistent with\u0000previous measurements and show for $^{140}$Ce a value $approx 15$% smaller\u0000than most recent experimental values.","PeriodicalId":501206,"journal":{"name":"arXiv - PHYS - Nuclear Experiment","volume":"53 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-06-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141521030","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
V. PiauCEA, DES, IRESNE, DER, Cadarache F-13108 Saint-Paul-Lez-Durance, FranceUniversité Paris-Saclay, CNRS/IN2P3, IJCLab, 91405 Orsay, France, A. GöökDepartment of Physics and Astronomy, Uppsala University, Box 516, 751 20 Uppsala, Sweden, S. OberstedtEuropean Commission, Joint Research Centre, Directorate for Nuclear Safety and Security, 2440 Geel, Belgium, A. OberstedtExtreme Light Infrastructure - Nuclear Physics, A. ChebboubiCEA, DES, IRESNE, DER, Cadarache F-13108 Saint-Paul-Lez-Durance, France, O. LitaizeCEA, DES, IRESNE, DER, Cadarache F-13108 Saint-Paul-Lez-Durance, France, M. VidaliEuropean Commission, Joint Research Centre, Directorate for Nuclear Safety and Security, 2440 Geel, Belgium
Isomers produced by spontaneous fission of ${}^{252}$Cf have been measured with the VESPA setup, composed of LaBr$_3$(Ce) detectors for fast $gamma$-ray spectroscopy and an ionization chamber for detecting fission fragments. Identification of the isomers was derived from fission fragment-$gamma$-$gamma$ coincidences. This paper presents the half-life of 34 isomeric states measured with this setup, from less than the nanosecond up to tens of microseconds. Two of these isomers are reported for the first time, in ${}^{108}$Tc and ${}^{147}$Ce. In addition to this half-life analysis, the isomers are used to develop and test a nuclear charge calibration of the ionization chamber.
{"title":"Characterization of isomers produced by the spontaneous fission of ${}^{252}$Cf with the VESPA setup","authors":"V. PiauCEA, DES, IRESNE, DER, Cadarache F-13108 Saint-Paul-Lez-Durance, FranceUniversité Paris-Saclay, CNRS/IN2P3, IJCLab, 91405 Orsay, France, A. GöökDepartment of Physics and Astronomy, Uppsala University, Box 516, 751 20 Uppsala, Sweden, S. OberstedtEuropean Commission, Joint Research Centre, Directorate for Nuclear Safety and Security, 2440 Geel, Belgium, A. OberstedtExtreme Light Infrastructure - Nuclear Physics, A. ChebboubiCEA, DES, IRESNE, DER, Cadarache F-13108 Saint-Paul-Lez-Durance, France, O. LitaizeCEA, DES, IRESNE, DER, Cadarache F-13108 Saint-Paul-Lez-Durance, France, M. VidaliEuropean Commission, Joint Research Centre, Directorate for Nuclear Safety and Security, 2440 Geel, Belgium","doi":"arxiv-2406.16823","DOIUrl":"https://doi.org/arxiv-2406.16823","url":null,"abstract":"Isomers produced by spontaneous fission of ${}^{252}$Cf have been measured\u0000with the VESPA setup, composed of LaBr$_3$(Ce) detectors for fast $gamma$-ray\u0000spectroscopy and an ionization chamber for detecting fission fragments.\u0000Identification of the isomers was derived from fission\u0000fragment-$gamma$-$gamma$ coincidences. This paper presents the half-life of\u000034 isomeric states measured with this setup, from less than the nanosecond up\u0000to tens of microseconds. Two of these isomers are reported for the first time,\u0000in ${}^{108}$Tc and ${}^{147}$Ce. In addition to this half-life analysis, the\u0000isomers are used to develop and test a nuclear charge calibration of the\u0000ionization chamber.","PeriodicalId":501206,"journal":{"name":"arXiv - PHYS - Nuclear Experiment","volume":"89 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-06-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141507884","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
E. A. George, T. E. Haugen, O. Naviliat-Cuncic, P. A. Voytas
The authors of Ref.[1] (referred to here as "Moskal et al.") claim to have performed the most precise test of P, T and CP invariance in the decay of ortho-Positronium. In this note: 1) we demonstrate, assuming standard properties for Compton scattering, that the average value of the correlation measured by Moskal et al. must necessarily be zero, independently of any physics occurring in o-Ps decay; 2) we point out that there is no formal justification to equate the normal vector to the Compton scattering plane with the incident photon polarization, as done by Moskal et al.; 3) we observe the absence of characterization of the device as a Compton polarimeter, which is paramount in photon polarimetry; 4) we review previous measurements of the polarization of photons from o-Ps decay, properly implementing the Compton polarimetry technique, and make the connection with tests of discrete symmetries; and 5) we stress that the correlation proposed by Moskal et al. cannot be generated solely by the physics of o-Ps decay, including possible violations of discrete symmetries.
{"title":"Comments on the publication \"Discrete symmetries tested at 10e-4 precision using linear polarization of photons from positronium annihilations\" by P. Moskal et al","authors":"E. A. George, T. E. Haugen, O. Naviliat-Cuncic, P. A. Voytas","doi":"arxiv-2406.16228","DOIUrl":"https://doi.org/arxiv-2406.16228","url":null,"abstract":"The authors of Ref.[1] (referred to here as \"Moskal et al.\") claim to have\u0000performed the most precise test of P, T and CP invariance in the decay of\u0000ortho-Positronium. In this note: 1) we demonstrate, assuming standard\u0000properties for Compton scattering, that the average value of the correlation\u0000measured by Moskal et al. must necessarily be zero, independently of any\u0000physics occurring in o-Ps decay; 2) we point out that there is no formal\u0000justification to equate the normal vector to the Compton scattering plane with\u0000the incident photon polarization, as done by Moskal et al.; 3) we observe the\u0000absence of characterization of the device as a Compton polarimeter, which is\u0000paramount in photon polarimetry; 4) we review previous measurements of the\u0000polarization of photons from o-Ps decay, properly implementing the Compton\u0000polarimetry technique, and make the connection with tests of discrete\u0000symmetries; and 5) we stress that the correlation proposed by Moskal et al.\u0000cannot be generated solely by the physics of o-Ps decay, including possible\u0000violations of discrete symmetries.","PeriodicalId":501206,"journal":{"name":"arXiv - PHYS - Nuclear Experiment","volume":"184 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-06-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141521037","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In heavy-ion collision experiments, the global collectivity of final-state particles can be quantified by anisotropic flow coefficients ($v_n$). The first-order flow coefficient, also referred to as the directed flow ($v_{1}$), describes the collective sideward motion of produced particles and nuclear fragments in heavy-ion collisions. It carries information on the very early stage of the collision, especially at large pseudorapidity ($eta$), where it is believed to be generated during the nuclear passage time. Directed flow therefore probes the onset of bulk collective dynamics during thermalization, providing valuable experimental guidance to models of the pre-equilibrium stage. In 2018, the Event Plane Detector (EPD) was installed in STAR and used for the Beam Energy Scan phase-II (BES-II) data taking. The combination of EPD ($2.1 <|eta|< 5.1$) and high-statistics BES-II data enables us to extend the $v_{1}$ measurement to the forward and backward $eta$ regions. In this paper, we present the measurement of $v_{1}$ over a wide $eta$ range in Au+Au collisions at $sqrt{s_{NN}}=$ 19.6 and 27 GeV using the STAR EPD. The results of the analysis at $sqrt{s_{NN}}=$19.6 GeV exhibit excellent consistency with the previous PHOBOS measurement, while elevating the precision of the overall measurement. The increased precision of the measurement also revealed finer structures in heavy-ion collisions, including a potential observation of the first-order event-plane decorrelation. Multiple physics models were compared to the experimental results. Only a transport model and a three-fluid hybrid model can reproduce a sizable $v_{1}$ at large $eta$ as was observed experimentally. The model comparison also indicates $v_{1}$ at large $eta$ might be sensitive to the QGP phase transition.
在重离子碰撞实验中，各向异性流系数（$v_n$）可以量化终态粒子的全局集合性。一阶流动系数也称为定向流动（$v_{1}$），描述了重离子碰撞中产生的粒子和核碎片的集体侧向运动。它携带着碰撞早期阶段的信息，尤其是在大的假振幅（$eta$）下，据信它是在核通过时间内产生的。因此，定向流探测了热化过程中块体集体动力学的开始，为前平衡阶段的模型提供了宝贵的实验指导。2018 年，事件平面探测器（Event Plane Detector，EPD）被安装在 STAR 上，用于光束能量扫描第二阶段（Beam Energy Scan phase-II，BES-II）的数据采集。结合EPD(2.1 <|eta|< 5.1$)和高统计BES-II数据，我们能够将$v_{1}$测量扩展到前向和后向$eeta$区域。本文介绍了利用STAR EPD在$sqrt{s_{NN}}=$ 19.6和27 GeV的Au+Aucollisions中对$v_{1}$的测量。在$/sqrt{s_{NN}}=$19.6 GeV下的分析结果与之前的PHOBOS测量结果具有极好的一致性，同时提高了整体测量的精度。测量精度的提高还揭示了重离子对撞中更精细的结构，包括对一阶事件面去相关性的潜在观测。多种物理模型与实验结果进行了比较。只有一个输运模型和一个三流体混合模型能够再现实验中观测到的大$ea$时的相当大的$v_{1}$。模型比较还表明大$ea$时的$v_{1}$可能对QGP相变很敏感。
{"title":"Measurement of directed flow in Au+Au collisions at $sqrt{s_{NN}}=$ 19.6 and 27 GeV with the STAR Event Plane Detector","authors":"STAR Collaboration","doi":"arxiv-2406.18213","DOIUrl":"https://doi.org/arxiv-2406.18213","url":null,"abstract":"In heavy-ion collision experiments, the global collectivity of final-state\u0000particles can be quantified by anisotropic flow coefficients ($v_n$). The\u0000first-order flow coefficient, also referred to as the directed flow ($v_{1}$),\u0000describes the collective sideward motion of produced particles and nuclear\u0000fragments in heavy-ion collisions. It carries information on the very early\u0000stage of the collision, especially at large pseudorapidity ($eta$), where it\u0000is believed to be generated during the nuclear passage time. Directed flow\u0000therefore probes the onset of bulk collective dynamics during thermalization,\u0000providing valuable experimental guidance to models of the pre-equilibrium\u0000stage. In 2018, the Event Plane Detector (EPD) was installed in STAR and used\u0000for the Beam Energy Scan phase-II (BES-II) data taking. The combination of EPD\u0000($2.1 <|eta|< 5.1$) and high-statistics BES-II data enables us to extend the\u0000$v_{1}$ measurement to the forward and backward $eta$ regions. In this paper,\u0000we present the measurement of $v_{1}$ over a wide $eta$ range in Au+Au\u0000collisions at $sqrt{s_{NN}}=$ 19.6 and 27 GeV using the STAR EPD. The results\u0000of the analysis at $sqrt{s_{NN}}=$19.6 GeV exhibit excellent consistency with\u0000the previous PHOBOS measurement, while elevating the precision of the overall\u0000measurement. The increased precision of the measurement also revealed finer\u0000structures in heavy-ion collisions, including a potential observation of the\u0000first-order event-plane decorrelation. Multiple physics models were compared to\u0000the experimental results. Only a transport model and a three-fluid hybrid model\u0000can reproduce a sizable $v_{1}$ at large $eta$ as was observed experimentally.\u0000The model comparison also indicates $v_{1}$ at large $eta$ might be sensitive\u0000to the QGP phase transition.","PeriodicalId":501206,"journal":{"name":"arXiv - PHYS - Nuclear Experiment","volume":"19 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-06-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141507885","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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