We want to extend to you our cordial invitation to the 42nd International Conference on High Energy Physics to be held 17-24 Jul 2024 in Prague, in the Czech Republic. No one can predict the results that will be shown here. Yet we may expect a rich harvest from the current LHC run as well as from other experiments. We will also like to hear about the European Strategy Update.
ICHEP is a series of international conferences organized by the C11 commission of the International Union of Pure and Applied Physics (IUPAP). It has been held every two years since more than 50 years, and is the reference conference of particle physics where most relevant results are presented.
At ICHEP, physicists from around the world gather to share the latest advancements in particle physics, astrophysics/cosmology, and accelerator science and discuss plans for major future facilities.
The 2024 International Workshop on Future Linear Colliders (LCWS2024) continues the series devoted to the study of the physics, detectors, and accelerator issues relating to high-energy linear electron-positron colliders. A linear collider will initially operate as a Higgs factory, and provides a clear path for upgrades in energy and luminosity.
Since the last workshop (LCWS2023), many significant steps have been made. With a wide program of plenary and parallel sessions, this workshop will provide an opportunity to present ongoing work and to get informed and involved.
The workshop is scheduled from the morning of 8th of July to the late afternoon of 11th of July. We plan to have an evening reception on the 8th, and a conference dinner on the 10th. The workshop will be held at the University of Tokyo (Hongo and/or Yayoi campus), located in the heart of Tokyo.
The goal of this conference is to draw a complete picture of the status of dark matter searches from the theoretical to the experimental point of view.
IDM 2024 is planned as an in-person conference on July 8-12, 2024. It will be held in L’Aquila, the capital city of the Abruzzo region in Italy. After the tragic earthquake of 2009 and the intense large-scale reconstruction of the last 14 years, L’Aquila has a strong commitment to innovation, science and technology.
This 15th IDM edition is jointly organized by the Gran Sasso Science Institute (GSSI), the Department of Physical and Chemical Sciences of the L’Aquila University (UnivAQ) and the National Gran Sasso Laboratory (LNGS). The city of L’Aquila is hungry for scientific and cultural events. Hosting three big scientific institutions, L’Aquila is a crossroads playing a crucial role in modern dark matter searches. LNGS is one of the most advanced underground facilities worldwide, hosting top-class experiments in a variety of particle physics fields. The Lab is an internationally recognized science centre and has an enormous cultural impact on the region. UnivAQ is a well-established reality with 17000 students and 7 departments, including Physics and Chemistry, Engineering, and Humanities. The excellence Ph.D. school GSSI, established in 2013 as part of the cultural renovation of the city, gained in a few years international relevance in its 4 research areas: Physics, Mathematics, Computer Science, and Social Studies.
The workshop will cover a broad range of issues in high-energy theory. Topics closer to gravity and cosmology have now been separated into a new workshop. The talks are expected to be informal and interactive, with a substantial pedagogical component. We strongly encourage blackboard presentations.
The workshop will be held at the physics department of Chulalongkorn University (commonly abbreviated as “Chula”, pronounced choo-lah, with a stressed second syllable), Thailand’s leading school in natural science fields centrally located in the modernized Pathumwan district of Bangkok.
The XXXI International Workshop on Deep Inelastic Scattering and Related Subjects (DIS2024) will be organized in Grenoble, France, from April 8 to April 12, 2024.
The conference covers a large spectrum of topics in high energy physics. A significant part of the program is devoted to the most recent theoretical advances and results from large experiments at BNL, CERN, DESY, FNAL, JLab and KEK.
The venue of the workshop is the Maison MINATEC congress center which is part of the scientific area Grenoble Presqu’Île close to the city center.
The 21st International Conference on Strangeness in Quark Matter (SQM 2024) will focus on new experimental and theoretical developments on the role of strange and heavy-flavour quarks in high energy heavy-ion collisions and in astrophysical phenomena.
Scientific topics include:
Strangeness and heavy-quark production in nuclear collisions and hadronic interactions
Hadron resonances in the strongly-coupled partonic and hadronic medium
Bulk matter phenomena associated with strange and heavy quarks
To advance our understanding of gluonic saturated matter at the LHC, the ALICE collaboration has presented a new study using photon-induced interactions in ultra-peripheral collisions (UPCs). In this type of collision, one beam emits a very high energetic photon that strikes the other beam, giving rise to photon–proton, photon–nucleus and even photon–photon collisions.
While we know that the proton – and most of the visible matter of the universe – is made of quarks bound together by gluons, quantum chromodynamics (QCD)has not yet provided a complete understanding of the rich physics phenomena that occur in high-energy interactions involving hadrons. For example, it is not known how the distribution of gluons evolve at low values of Bjorken-x. The rapid increase in gluon density observed with decreasing x cannot continue forever as it would eventually violate unitarity. At some point “gluon saturation” must set in to curb this growth.
So far, it has been challenging to experimentally establish when saturation sets in. One can expect, however, that it should occur at lower energies for heavy nuclei than for protons. Thus, the ALICE Collaboration has studied the energy dependence of UPC processes for both protons and heavy nuclei. At the same time, other physics phenomena, such as gluon shadowing originating from multi-scattering processes, can exist with similar experimental signatures. The interplay between these phenomena is still an open problem in QCD.
ALICE has presented new results on J/ψ meson-production UPC, where the photon probes the whole nucleus. The new ALICE results, analysed using LHC Run 1 and Run 2 data, probe a wide range of photon-nucleus collision energies from around 10 GeV to 1000 GeV. These results confirm previous measurements by ALICE, obtained at lower energies, that indicated a strong nuclear suppression when such photon–nucleus data are compared to expectations from photon–proton interactions. The present analysis employs novel methods for extracting the energy dependence, providing new information to test theoretical models. The present data at high energies can be described by both saturation-based and gluon shadowing models. The coherent J/ψ meson production at low energy, in the anti-shadowing region, is not described by these models, nor can available models fully describe the energy dependence of this process over the explored energy range.
ALICE will continue to investigate these phenomena in LHC Runs 3 and 4, where high-precision measurements with larger data samples and upgraded detectors will provide more powerful tools to better understand gluonic saturated matter.
Charge-parity (CP) violation parameters in tree-dominated b → c c s quark transitions are a powerful probe of physics beyond the Standard Model (SM). When B0(s) and B0(s) mesons decay through these transitions to the same final-state particles, an interference between mixing and decay amplitudes occurs, making these processes particularly sensitive to CP violation.
In the SM, B0(s) – B0(s) mixing is possible because the flavour eigenstates are not the (physical) mass eigenstates: a neutral B meson, once produced, evolves as a quantum superposition of B0(s) and B0(s) states. Due to this time-dependent mixing amplitude, an interference between mixing and decay amplitudes can lead to an observable time-dependent CP asymmetry in the decay rates. It was through the observation of this phenomenon in the “golden mode” B0→ J/ψ K0s that, in 2001, the BaBar and Belle collaborations reported the first unequivocal evidence for CP violation in B decays, for which Kobayashi and Maskawa were awarded the 2008 Nobel Prize in Physics.
As the 3 × 3 Cabibbo–Kobayashi–Maskawa (CKM) matrix that describes quark mixing in the SM is expected to be unitary, it leads to relations among its complex elements. These can be represented as triangles in a complex plane, all of them with the same area (which is a measure of the amount of CP violation in the SM). The most famous of them, the so-called unitary triangle, has sides of roughly the same size and internal angles denoted as α, β and γ. Since individually none of the CKM parameters are predicted by theory, the search for new physics relies on over-constraining them by looking for any hint of internal inconsistency. For that, precision is the key.
LHCb has become a major actor in precision studies of CP violation
Having analysed the full proton–proton collision data set with 13 TeV, and adding it to previous measurements at 7 and 8 TeV, LHCb recently brought the CP-violating parameters in B0→ J/ψ K0sand in another golden channel, B0s→ J/ψ K+K–, to a new level of precision. These parameters (sin2β and φs, respectively) are predicted with high accuracy through global CKM fits and, given their clean experimental signatures, are paramount for new-physics searches. The measured time-dependent CP asymmetry of B0 and B0 decay rates is shown in figure 1 with the resulting amplitude proportional to sin2β. Similarly, the update of the B0s→ J/ψ K+K– analysis with the 13 TeV data resulted in the world’s most precise φs measurement. Both angles agree with SM expectations and with previous measurements.
These legacy results for sin2β and φs from the first LHC runs represent a new milestone in LHCb’s hunt for physics beyond the SM. Along with the world-leading determination of γ (with a current precision of less than four degrees), and the discovery of CP violation in charm in 2019, LHCb has fulfilled and exceeded its own goals of more than a decade ago, becoming the major actor in precision studies of CP violation. LHCb is taking data with a brand new detector at larger interaction rates than before, boosting the experimental sensitivity and tightening the grip around the Standard Model.
Since the discovery of the Higgs boson in 2012, its di-photon and four-lepton decays have played a crucial role in characterising its properties. Despite their small branching ratios, these decay channels are ideal for accurate measurements due to the excellent resolution and efficient identification of photons and leptons provided by the ATLAS detector.
The Higgs-boson mass (mH) is a free parameter of the Standard Model (SM) that must be determined experimentally. Its value governs the coupling strengths of the Higgs boson with the other SM particles. It also enters as logarithmic corrections to the SM predictions of the W-boson mass and effective weak mixing angle, whose precise measurements allow the electroweak model to be tested. Moreover, the Higgs mass determines the shape and energy evolution of the Brout–Englert–Higgs potential and thus the stability of the electroweak vacuum. A precise measurement of mH is therefore of paramount importance.
ATLAS has recently published a new result of the Higgs-boson mass in the H → γγ decay channel using proton–proton collision data from LHC Run 2 (2015–2018). The measurement requires a careful control of systematic uncertainties, primarily arising from the photon energy scale. The new analysis has achieved a substantial reduction by more than a factor of three of these uncertainties compared to the previous ATLAS result based on the 2015 and 2016 dataset. That improvement became possible after extensive efforts to refine the photon energy-scale calibration and associated uncertainties.
The calibration benefited from an improved understanding of the energy response across the longitudinal ATLAS electromagnetic calorimeter layers and of nonlinear electronics readout effects. A new correction was implemented in the extrapolation of the precisely measured electron-energy scale in Z → e+e– events to photons, to account for differences in the lateral shower development between electrons and photons. These improvements reduced the systematic uncertainty in the mass measurement by about 40%. Moreover, the extrapolation of the electron energy scale from Z → e+e– events to photons originating from the Higgs boson was further refined, and transverse-momentum dependent effects were corrected. Taken together, the improvements allowed ATLAS to measure the Higgs-boson mass in the di-photon channel with a precision of 1.1 per mille.
The new di-photon result was combined with the mH measurement in the H → ZZ*→ 4ℓ decay using the full Run 2 dataset, published by ATLAS in 2022, and with the corresponding Run 1 (2011–2012) measurements (see figure 1). The resulting combined Higgs-boson mass mH = 125.11 ± 0.11 GeV has a precision of 0.9 per mille and is dominated by statistical uncertainties that will further reduce with the Run 3 data.
The high level of readiness and excellent performance of the ATLAS detector also allowed first measurements of the fiducial Higgs-boson production cross-sections in the H → γγ and H → ZZ*→ 4ℓ decay channels using up to 31.4 fb–1 of data collected in 2022. Their extrapolation to full phase space and combination gives σ(pp → H) = 58.2 ± 8.7 pb, which agrees with the SM prediction of 59.9 ± 2.6 pb (see figure 2).
With the continuation of Run 3 data taking, the precision of the 13.6 TeV cross-section measurements will improve and the combination with the Run 2 data will allow the exploration of Higgs-boson properties with growing sensitivity.
