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LHCb - Charge Asymmetry in Three-Body Decays with LHCb
No full textThe study of charge asymmetries in three-body ± → h h h decays provides a sensitive probe of CP violation in the beauty sector. Using the first data collected during LHCb Run 3, we are performing a preliminary investigation aimed at measuring these asymmetries through fits to the invariant mass distributions of selected candidates. The upgraded detector and higher instantaneous luminosity of Run 3 are expected to improve signal-to-background separation and reduce systematic uncertainties, offering enhanced sensitivity compared to previous runs. This ongoing study will lay the groundwork for precise tests of the Standard Model and potential exploration of effects beyond it
Design, Fabrication and Concept for the Surface Treatment of the SRF Cavity Prototype for the CLIC Damping Rings
No full textThe Compact Linear Collider (CLIC) Damping Rings (DRs) need to generate ultra-low emittance bunches to achieve high luminosity in CLIC. This requires many wiggler magnets with big energy loss which is compensated by the Radio Frequency (RF) system. The resulting strong beam loading transients lead to a challenging design for the RF system. A novel SRF cavity at 2 GHz with an ultra-low R/Q parameter of below 1 Ω is proposed to minimize the transient beam loading effects below acceptable level. The design and fabrication of the bulk Nb prototype based on turning from a single piece of Nb and EB welding is presented. Moreover, conceptual study of the system for cavity surface treatment to achieve the highest surface magnetic field which is the main goal of the prototype cold test is described as well. To enable excellent performance in this cavity, we plan to apply the 75/120C modified low temperature bake in combination with the cold electropolishing process. This surface treatment approach has been shown to consistently deliver high accelerating gradients and improved quality factors in TESLA-shaped 1.3 GHz SRF cavities. By adapting and implementing this process for the 2 GHz ultra-low R/Q design, we aim to maximize the achievable surface magnetic field while minimizing residual resistance and field emission. This treatment strategy will be critical for demonstrating that the cavity can meet the demanding performance requirements of the CLIC damping ring RF system under high beam loading conditions
Construction and commissioning of RPC and sMDT chambers for the innermost layer of the ATLAS HL-LHC Muon Barrel upgrade
No full textThe current ATLAS Muon Barrel system is undergoing a major upgrade, consisting in the installation of approximately 1000 RPC detector units of new generation in the innermost layer of the ATLAS Muon Spectrometer along with new sMDT (small Monitored Drift Tube) detectors in the Small (BIS) sectors. The goal of the RPC project is to increase the detector coverage, currently limited to approximately 80%, and improve the trigger robustness and efficiency. The production of the gas volumes takes place in factories in Italy, in MPI and USTC, while the readout panels in Cosenza and USTC. Here we present the state of the art of the production, certification and logistics related to all the components produced at the INFN Institutes for the RPC to be installed in the Large sectors (BIL), as well as the assembly line and characterization of the BIL chambers at CERN. The certification results of the components produced are analyzed and discussed. To provide space for the additional RPC chambers, the existing 30 mm BIS MDT will be replaced by 15 mm sMDT. The sMDTs will maintain high muon tracking resolution (better than 100 µm per tube) and will accommodate higher event rates. We will present the commissionig status and performance of sMDT chambers manufactured by US and Germany institutes
Hyperon global polarization in isobar Ru+Ru and Zr+Zr collisions at <math altimg="si15.svg"><mrow><msqrt><msub><mi>s</mi><msub><mrow/><mrow><mrow><mi mathvariant="normal">N</mi></mrow><mi>N</mi></mrow></msub></msub></msqrt><mo linebreak="goodbreak">=</mo><mn>200</mn><mrow><mrow><mi mathvariant="normal">G</mi></mrow><mi>e</mi><mi>V</mi></mrow></mrow></math>
No full textThe polarization of Λ, Λ¯, Ξ−, and Ξ¯+ hyperons along the angular momentum of the system has been measured in isobar collisions of Ru+Ru and Zr+Zr at sNN = 200 GeV with the STAR detector at RHIC. The polarization dependence on collision centrality exhibits an increasing trend in more peripheral collisions. Λ and Λ¯ polarization dependence on the transverse momentum and pseudorapidity have been investigated, but no significant dependence was observed. The polarizations of Λ and Λ¯ are found to be consistent with each other, indicating little contribution of the spin-magnetic coupling to the measured polarization. Comparison to previously measured polarization in Au+Au collisions show no obvious system size dependence. The results are qualitatively consistent with hydrodynamic calculations including contributions from shear-induced polarization and thermal vorticity. For the first time in heavy-ion collisions, the dependence of the global polarization on the hyperon’s emission azimuthal angle relative to the second-order event plane has been measured, indicating stronger polarization for the in-plane emitted hyperons at the level of 2.4σ significance in 20–50 % centrality. The Ξ hyperon polarization measurements via polarization transfer analysis yield finite positive values with 2.9σ significance in 20–50 % centrality, slightly larger compared to the inclusive Λ polarization.The polarization of Lambda, Anti-Lambda, Xi, and Anti-Xi hyperons along the angular momentum of the system has been measured in isobar collisions of Ru+Ru and Zr+Zr at = 200 GeV with the STAR detector at RHIC. The polarization dependence on collision centrality is explored and found to show an increasing trend in more peripheral collisions. Dependencies on transverse momentum and pseudorapidity are investigated for Lambda and Anti-Lambda hyperons, but no significant dependence has been observed. The polarization measurements for Lambda and Anti-Lambda are consistent with each other, indicating little contribution of the spin-magnetic coupling in the observed polarization. The results for Lambda hyperons measurements are qualitatively consistent with hydrodynamic calculations incorporating effects from shear-induced polarization and thermal vorticity, and show no obvious system size dependence in comparison with previous results in Au+Au collisions. For the first time, the dependence of the polarization on the hyperon's emission azimuthal angle with respect to the second harmonic event plane is extracted and shows stronger polarization for the in-plane emitted hyperons at the level of 2.4 significance in 20-50% centrality. The measurements of Xi hyperons polarization via the polarization transfer analysis exhibit a finite positive polarization, 2.9 significance in 20-50% centrality, slightly enhanced compared to the inclusive Lambda polarization
Progress pride flag flying at CERN
No full textProgress pride flag flying at CERN on 18 November 2025 for LGBTQ Da
The Phase-II upgrade projects of ATLAS Tile Calorimeter for the high-luminosity era
No full textSlides for IPRD 2025- Siena "The Tile Calorimeter (TileCal) is the central hadronic calorimeter of the ATLAS experiment at the Large Hadron Collider (LHC). In preparation for the High-Luminosity phase of the LHC, expected to begin in 2030 and delivering a factor of 5 to 7.5 larger the nominal instantaneous luminosity, a comprehensive upgrade of the TileCal electronics is underway. This upgrade is essential to meet the challenges of a 1 MHz trigger rate, higher ambient radiation levels, and increased pile-up conditions. Scheduled for implementation during the Long Shutdown from 2026 to 2030, the upgrade involves a complete replacement of both on- and off-detector electronics, along with the replacement of approximately 10% of the photomultiplier tubes in the most exposed detector cells. A key feature of the upgraded system is the direct digitization of signals from every TileCal channel, followed by transmission to the back-end electronics. Here, the signals will be reconstructed, stored, and forwarded to the first level of the trigger system at a rate of 40 MHz. This enhanced dataflow will significantly improve the precision of the calorimeter signals available to the trigger, allowing the development and implementation of more sophisticated and effective trigger algorithms. The new modular front-end electronics are designed with radiation-tolerant components and incorporate a redundant architecture to minimize the impact of single points of failure. Communication and control between the on- and off-detector systems will be facilitated by modern Field Programmable Gate Arrays and high-speed fiber optic links running up to 9.6 Gb/s. The TileCal upgrade program has included extensive research and development efforts, including detailed test beam studies and the construction of a Demonstrator module. This Demonstrator, featuring the new electronics but designed for reverse compatibility with the existing ATLAS Trigger and Data Acquisition system, was inserted into ATLAS in 2019 for operating under real detector conditions. The ongoing progress in the development of both the on- and off-detector systems, the latest results obtained from test-beam campaigns conducted with the electronics prototypes, as well as the findings from the Demonstrator module's operation within ATLAS will be discussed.
Di-Higgs searches at CMS
No full textThis proceeding presents the CMS searches for the nonresonant production of Higgs boson pairs in proton--proton collisions at a centre-of-mass energy of 13~TeV.
The analyses use the full Run~2 dataset collected with the CMS detector during 2016--2018, corresponding to an integrated luminosity of 138~fb.
Several final states with complementary sensitivities are explored, including
,
,
,
,
,
multilepton,
,
and , together with a dedicated search for the associated production included in the global interpretation.
The observed (expected) upper limit on the inclusive Higgs boson pair production cross section relative to the Standard Model prediction is 3.5 (2.5) at 95\% confidence level.
Assuming all other Higgs boson couplings take their Standard Model values, the trilinear self-coupling modifier is constrained to
at 95\% confidence level.
For the quartic vector-boson--Higgs coupling modifier, is excluded with a significance of 6.6 standard deviations, with an allowed interval of
at 95\% confidence level.
The results are interpreted within the Higgs Effective Field Theory, setting upper limits across established benchmarks and on the contact-interaction coefficient.
An extrapolation to the integrated luminosity expected after the High-Luminosity LHC upgrade illustrates the projected improvement in sensitivity to nonresonant production and to the Higgs boson self-coupling.
Combining single- and double-Higgs measurements further refines the determination of the trilinear coupling, with
when other couplings are fixed and
when they are allowed to vary
Search for new heavy resonances decaying to higgs boson pairs in boosted bbtautau final states
No full textA search is presented for massive narrow-width resonances in the mass range of decaying into pairs of Higgs bosons (HH), using proton-proton collision data at a center-of-mass energy of collected with the CMS detector at the LHC during the data-taking. The data correspond to an integrated luminosity of . The analysis targets final states where one Higgs boson decays into a pair of bottom quarks and the other into a pair of tau leptons, . The observed data are found to be consistent with standard model background expectations. Upper limits at confidence level (CL) are set on the production cross section for resonant HH production for masses between and . This analysis sets the most sensitive LHC limits to date on decays in the mass range of to
