We are pleased to announce that this year’s HEFT workshop will take place in Manchester in June 2023.
HEFT is an annual workshop focusing on the use of effective field theories to search for physics beyond the Standard Model. A broad range of topics are encouraged, ranging from collider phenomenology and formal aspects to the latest experimental updates on dedicated searches. The meeting aims to foster discussions between theorists and phenomenologists from varied backgrounds as well as with experimental colleagues.
The 2023 edition is organised by the Particle Theory Group of the University of Manchester. The workshop will begin on June 19th morning and in the afternoon on June 21st.
Abstract submission is open. Abstracts are particularly welcome also from junior scientists (PhD students, young postdocs).
For more information and some accommodation suggestions, see also: https://heft2023.com
Please be aware of scam emails offering to organise accommodation for you!
Studies of the Higgs boson by ATLAS and CMS have observed and measured a large spectrum of production and decay mechanisms. Its relatively long lifetime and low expected width (4.1 MeV, compared with the GeV-range decay widths of the W and Z bosons) make the Higgs boson a sensitive probe for small couplings to new states that may measurably distort its branching fractions. The search for invisible or yet undetected decay channels is thus highly relevant.
Dark-matter (DM) particles created in LHC collisions would have no measurable interaction with the ATLAS detector and thus would be “invisible”, but could still be detected via the observation of missing transverse momentum in an event, similarly to neutrinos. The Standard Model (SM) predicts the Higgs boson to decay invisibly via H → ZZ*→ 4ν in only 0.1% of cases. However, this value could be significantly enhanced if the Higgs boson decays into a pair of (light enough) DM particles. Thus, by constraining the branching fraction of Higgs-boson decays to invisible particles it is possible to constrain DM scenarios and probe other physics beyond the SM (BSM).
The ATLAS collaboration has performed comprehensive searches for invisible decays of the Higgs boson considering all its major production modes: vector-boson fusion with and without additional final-state photons, gluon fusion in association with a jet from initial-state radiation, and associated production with a leptonically decaying Z boson or a top quark–antiquark pair. The results of these searches have now been combined, including inputs from Runs 1 and 2 analyses. They yield an upper limit of 10.7% on the branching ratio of the Higgs boson to invisible particles at 95% confidence level, for an unprecedented expected sensitivity of 7.7%. The result is used to extract upper limits on the spin-independent DM-nucleon scattering cross section for DM masses smaller than about 60 GeV in a variety of Higgs-portal models (figure 1). In this range and for the models considered, invisible Higgs-boson decays are more sensitive than the results from DM-nucleon scattering detection experiments.
An alternative way to constrain possible undetected decays of the Higgs boson is to measure its total decay width ΓH. Combining the observed value of the width with measurements of the branching fractions to observed decays allows the partial width for decays to new particles to be inferred. Directly measuring ΓH at the LHC is not possible as it is much smaller than the detector resolution. However, ΓH can be constrained by taking advantage of an unusual feature of the H → ZZ(*) decay channel: the rapid increase in available phase space for the H → ZZ(*) decay as mH approaches the 2mZ threshold counteracts the mass dependence of Higgs-boson production. Furthermore, this far “off-shell” production above 2mZ has a negligible ΓH dependence, unlike “on-shell” production near the Higgs-boson mass at 125 GeV. Comparing the Higgs-boson production rates in these two regions therefore allows an indirect measurement of ΓH. Although some assumptions are required (e.g. that the relation between on-shell and off-shell production is not modified by BSM effects), the measurement is sensitive to the value of ΓH expected in the SM. Recently, ATLAS measured the off-shell production cross-section using both the four-charged lepton (4l) and two-charged lepton plus two neutrino (2l2v) final states, finding evidence for off-shell Higgs-boson production with a significance of 3.3 σ (figure 2). By combining both the previously measured on-shell Higgs-boson production-cross section and the of-shell Higgs-boson production-cross section, ΓH was found to be 4.5+3.3–2.5 MeV, which agrees with the SM prediction of 4.1 MeV but leaves plenty of room for possible BSM contributions.
This sensitivity will improve thanks to the new data to be collected in Run 3 of the LHC, which should more than triple the size of the Run 2 dataset.
The 20th International Conference on Hadron Spectroscopy and Structure (HADRON 2023) is to be held in Genova, Italy, from June 5th to 9th 2023.
This series of conferences started in 1985 at Maryland, USA. It brings together experimentalists and theorists every other year to review the status and progress in hadron spectroscopy, structure and related topics and to exchange ideas for future explorations.
Dark Matter 2023: From the Smallest to the Largest Scales is a conference devoted to discussing the latest developments in the field of dark matter, from experiments to theory and phenomenology. DM2023 will be held at Hotel Chiqui, just a few steps from the beautiful Sardinero Beach in the city of Santander, a well known Summer resort on the northern coast of Spain.
The meeting starts on the afternoon of May 29th and will end after the morning session on Jun 2nd.(approx. at 1:30 PM). On Tuesday 30th May, we will enjoy a welcome cocktail reception (included in the conference fee) at the beautiful Palacio de la Magdalena.
The Flavor Physics and CP Violation (FPCP) conferences are intended for the exchange of new ideas, for presentation of the latest experimental and theoretical results in the areas included in the conference title, and for discussions about future projects in the field. The conference is open to all experimental and theoretical physicists interested in the field.
This conference series results from the merging of the Heavy Flavor Physics Conference and the International Conference on B Physics and CP Violation in 2002.
The 25th Planck conference in the series “From the Planck scale to the electroweak scale” will take place in Warsaw, May 22-26, 2023. It will be focused on “Hot topics in particle physics and cosmology: theory facing experimental prospects”. Thus, its mostly theoretical character will be guided and organized according to the following blocks:
The concepts of using quantum information methods and tools in high-energy physics are triggering more and more attention in our community in recent years, after the pioneering workshop which took place at the Brookhaven National Laboratory in 2018. We are convinced that now it is the time for the follow-up and the discussion of new achievements.
Registration:
Registration and call for abstracts were closed on April, 14.
Conference fee:
There is a conference fee of 200 EUR (900 PLN) which covers lunches and coffee breaks. Please make a bank transfer to one of the following bank accounts:
payment in PLN: PL07 1240 4722 1111 0000 4855 9692
payment in EUR: PL04 1240 2294 1978 0010 7072 2467
A major goal in strong-interaction physics is to understand the nature of hadrons, which make up visible matter, and much research activity revolves around two fundamental questions: what are hadrons made up of and how does Quantum Chromo-dynamics (QCD), the strong-interaction component of the Standard Model, produce them? Although these questions are simple, the answers may not be. To address these questions, spectroscopy is a valuable and time-honored tool, as it enables us to understand the structure of mesons, baryons and exotics and how they are produced. In this context, the recent discovery of many new hadronic states, in particular the plethora of observed X, Y, Z states, is exciting, as these objects challenge the commonplace view of hadrons as either quark-antiquark or three-quark color-singlet states.
Experimental investigations of the hadron structure and spectrum are performed via hadron-hadron scattering processes, photo- and electro-production by nucleons or, more recently, by means of heavy-meson decays at world-wide accelerator facilities. In the last decade, these investigations have yielded an enormous amount of data, which have vastly improved our knowledge of the baryon and meson spectrum and enabled us to establish the existence of new states, together with an empirical determination of their angular momentum, content, and spin. Recent highlights are observations of multi-quark states outside our well-known hadronic pictures, which have been interpreted as the long sought-after penta- and tetraquark systems.
However, identifying new states and their quantum numbers requires complex analysis (so-called partial wave analysis), which sometimes relies on model assumptions. For many of the new states, we still do not know the quantum numbers. Different theoretical models for the structure of the new states give different predictions of their quantum numbers. Therefore, the composition of many states remains controversial. Indeed, some of these newly discovered hadrons seem to fit the picture of compact multi-quark states, while others may qualify as molecular states or both, i.e. the superposition of a constituent-quark core and a meson cloud, and one of the main goals of this workshop will be to discuss how to distinguish them.
The International Conference “Dark Matter and Stars: Multi-Messenger Probes of Dark Matter and Modified Gravity” aims to bring together scientists working across the different research fields of astrophysics, cosmology, and modified gravity. We want to look at the dark matter problem from different perspectives, considering it to be of particle nature, as well as modification of gravity. This meeting is intended to initiate cross-field discussions of dark matter searches, their current status, and future prospects.
CONFERENCE TOPICS
Dark matter in compact stars (neutron stars, white dwarfs, exotic stars)
Multi-messenger and gravitational wave probes of dark matter
Models of dark matter
Cosmology
Modified gravity
We seek to encourage dialogue between different research groups to enhance collaboration and help to improve our understanding of dark matter. The conference is also planned to introduce the dark matter research field to encourage attendance by young scientists including Ph.D. students.
The meeting will be held at the Centro de Congressos, Center for Astrophysics and Gravitation, Instituto Superior Técnico, University of Lisbon, Portugal.
PARTICIPANTS
Registration for the conference is free of charge. Maximum attendance is 120, to ensure all participants are comfortable and have ample opportunities to interact with one another. The selection of the final participant list is the responsibility of the organizing committee. Participants are chosen according to availability and conference goals, as explained above.
Neutrinoless double-beta decay (0νββ) remains as elusive as ever, following publication of the final results from the Majorana Demonstrator experiment at SURF, South Dakota, in February. Based on six years’ monitoring of ultrapure 76Ge crystals, corresponding to an exposure of 64.5 kg × yr, the collaboration has confirmed that the half-life of 0νββ in this isotope is greater than 8.3 × 1025 years. This translates to an upper limit of an effective neutrino mass mββ of 113–269 meV, and complements a number of other 0νββ experiments that have recently concluded data-taking.
Whereas double-beta decay is known to occur in several nuclides, its neutrinoless counterpart is forbidden by the Standard Model. That’s because it involves the simultaneous decay of two neutrons into two protons with the emission of two electrons and no neutrinos, which is only possible if neutrinos and antineutrinos are identical “Majorana” particles such that the two neutrinos from the decay cancel each other out. Such a process would violate lepton-number conservation, possibly playing a role in the matter–antimatter asymmetry in the universe, and be a direct sign of new physics. The discovery that neutrinos have mass, which is a necessary condition for them to be Majorana particles, motivated experiments worldwide to search for 0νββ in a variety of candidate nuclei.
Germanium-based detectors have an excellent energy resolution, which is key to be able to resolve the energy of the electrons emitted in potential 0νββ decays. The Majorana Demonstrator is also located 1.5 km underground, with low-noise electronics and ultrapure in-house-grown electroformed copper surrounding the detectors to shield it from background events. Despite a lower exposure, the collaboration was able to achieve similar limits to the GERDA experiment at Gran Sasso National Laboratory, which set a lower limit on the 76Ge 0νββ half-life of 1.8 × 1026 yr. Also among the projects of the collaboration is an ongoing search for the influence of dark-matter particles in the decay of metastable 180mTa – nature’s rarest isotope. Although no hints have been found so far, the search has already improved the sensitivity of dark-matter searches in nuclei significantly.
The search has already improved the sensitivity of dark-matter searches in nuclei significantly
Other experiments, such as KamLAND- ZEN and EXO-200, use 136Xe to search for 0νββ. While the former recently set the most stringent limit of 2.3 × 1026 yr and is ongoing, the latter arrived at a value of 3.5 × 1025 yr with a total 136Xe exposure of 234.1 kg × yr based on its full dataset. Searches at Gran Sasso with CUORE using 1t × yr exposure of 130Te led to a half-life of 2.2 × 1025 yr and at CUORE’s successor, CUPID-0, which used 82Se with a total exposure of 8.82 kg × yr, of the order 1023 yr.
Having demonstrated the required sensitivity for 0νββ detection in 76Ge, the designs of Majorana Demonstrator and GERDA have been incorporated into the next-generation experiment LEGEND-200, which uses high-purity germanium detectors surrounded by liquid argon. The experiment, based at Gran Sasso, started operations last spring and could have initial results later this year, says co-spokesperson Steven Elliot (LANL): “Once all the detectors are installed, we plan to run for five years, while the next stage, LEGEND-1000, is proceeding through the DOE Critical Decision process. We hope to begin construction in summer 2026, with first data available early next decade.”
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