2561 DPyC SMF false [["minutes", "Minutes"], ["notes", "Notes"], ["paper", "Paper"], ["poster", "Poster"], ["slides", "Slides"], ["summary", "Summary"]] Cinvestav ea481e58ca9c64e14d7982cb66bcd604 3312 The Division of Particles and Fields of the Mexican Physical Society (DPyC-SMF) organizes every year the Annual Meeting (RADPyC). This space is dedicated mainly for the exposure of results of graduate students and young researchers working in high energy physics and includes some review talks on the hot topics of the field. This year the meeting will be held in Auditorio José Ádem, Cinvestav, Mexico City, México. The scientific programme will consist of invited and contributed talks, and a poster session. It will begin in the morning of Wednesday 17 June and end before lunch on Friday 19 June. We will have the following invited talks: - Ana Colmenero, HAWC (UMSNH) - Jens Erler, The EW SM and constraints on NP (Mainz, PRISMA) - Iván Martínez Soler, Neutrino physics (Durham Univ.) - Cristina Oropeza, CMS (Ibero) - Antonio Ortiz, ALICE (ICN-UNAM) - Gabriel Palacios, Accelerator physics (UNAM) - Antonio Pich, Flavor physics (IFIC) - Pedro Podesta, Belle-II (UAS) - Selomit Ramírez, QCD, Loop Tree Duality, Quantum Computing (UAS) - Saúl Ramos, Flavor physics from a top-down perspective (IF-UNAM) - Alfredo Raya, NICA (UMSNH) - Eric Vázquez, DM-neutrinos (exp.) (IF-UNAM) The whole event can be followed by Zoom: https://us02web.zoom.us/j/85815121456?pwd=t1JWdqhgarEQRyewmXIEzNlkIcqU8a.1 (858 1512 1456 & 044752). Due to recent internet security problems at Cinvestav it will NOT be broadcasted via the DPyC facebook account (facebook is currently blocked on our premises). False 2026-06-17T09:00:00 2026-06-19T14:30:00 2026-03-23T09:50:55 2026-06-19T17:51:55 Mexico/General cinvestav f09241183e84638d226a8885656239cd Cinvestav 6be00aeecce15d4b2547496f45352003 CINVESTAV-IPN Mexico 207484e6583dd9c0c1af2f52ce04fdd8 Cinvestav ea481e58ca9c64e14d7982cb66bcd604 Cinvestav 3cd3ab69a079e614c15e4c750e7d3d60 BUAP 5848375cb8b0db28e94350f19dcb744f Benemérita Universidad Autónoma de Puebla 65efd11437264d48aa1f7486255a57bc 57 false [["minutes", "Minutes"], ["notes", "Notes"], ["paper", "Paper"], ["poster", "Poster"], ["slides", "Slides"], ["summary", "Summary"]] Instituto de Ciencias Nucleares a06c7a7c664e4bc870093f6eba2cbccf Instituto de Ciencias Nucleares a06c7a7c664e4bc870093f6eba2cbccf ICN, UNAM abd2500ad36bcdc84ec4489206dc6109 UNAM ICN bfbcb0947232ec4b8ef99df10a726799 00:15 Recent ALICE measurements of ultra-long-range azimuthal correlations ($|\Delta\eta|>5$) in low-multiplicity pp collisions at $\sqrt{s}=13$~TeV ($\mathrm{d}N_{\mathrm{ch}}/\mathrm{d}\eta<7$) have revealed significant discrepancies with both hydrodynamic and Color Glass Condensate estimations, challenging the traditional picture of collective behavior in small systems. In this work, we perform a systematic investigation of the origin of finite second-order two-particle correlation coefficients $V_{2\Delta}$ in the low-multiplicity regime using the PYTHIA8 event generator with the string-shoving mechanism, where repulsive interactions between overlapping color strings generate collective-like effects without invoking a thermalized medium. We employ the template-fit method to extract $V_{2\Delta}$ while subtracting non-flow contributions. Crucially, we compare three different event activity estimators, namely, mid-rapidity charged-particle multiplicity $N_{\mathrm{ch}}$, the number of multiparton interactions $N_{\mathrm{mpi}}$, and the recently proposed event-shape observable flattenicity $(1-\rho_{\mathrm{nch}})$. Our results reveal a counter-intuitive finding: the strongest ultra-long-range azimuthal correlations arise not in high-multiplicity events, but in events with low $N_{\mathrm{mpi}}\approx 1$ (dijet-dominated events), where the anisotropic geometry of a few overlapping strings and beam remnants enables efficient string shoving. The correlation strength diminishes with increasing $N_{\mathrm{mpi}}$ due to geometric cancellation and dilution effects. We demonstrate that the traditional $N_{\mathrm{ch}}$-based event classification introduces a significant bias, mixing isotropic MPI-rich events with jet-dominated topologies, which artificially suppresses the extracted $V_{2\Delta}$ and worsens the apparent failure of the model. In contrast, flattenicity — which quantifies global event topology — selects cleaner correlation structures with reduced hard-process bias and reveals the built-in saturation mechanism of the string-shoving model. Furthermore, we show that the low-multiplicity templates used for non-flow subtraction already contain intrinsic flow-like correlations from string shoving, leading to oversubtraction in higher activity classes. Our findings support a picture of gradual onset of collectivity, where initial-state string-shoving effects dominate in low-multiplicity pp collisions, while final-state hydrodynamic collective expansion becomes increasingly relevant at high multiplicities. This work strongly advocates for moving beyond $N_{\mathrm{ch}}$-based analyses toward global, topology-sensitive estimators like flattenicity for unbiased interpretation of collective phenomena in small collision systems. slides doc http://indico.nucleares.unam.mx/images/word.png word file ppt http://indico.nucleares.unam.mx/images/powerpoint.png powerpoint file pdf http://indico.nucleares.unam.mx/images/pdf_small.png pdf file odt http://indico.nucleares.unam.mx/images/writer.png writer file odp http://indico.nucleares.unam.mx/images/impress.png presentation file ods http://indico.nucleares.unam.mx/images/calc.png spreadsheet file other http://indico.nucleares.unam.mx/images/file_small.png unknown type file link http://indico.nucleares.unam.mx/images/link.png link