Interview with Federico Sanchez about the recent results of T2K collaboration
Recently the T2K experiment published in Nature their results on the constraint of leptonic CP violation. Although there is no one-to-one link between the matter antimatter asymmetry and the value of delta from the T2K measurement, these results are a major step forward in the study of difference between matter and antimatter. Federico Sanchez explains how T2K measures CP violation and what they can conclude.
Congratulations for your results and their publication. Can you explain why a different behaviour of matter and antimatter is so important?
Inside the Super-K detector. Credit: Kamioka Observatory, Institute for Cosmic Ray Research, University of Tokyo
The different behavior of particle and antiparticles, or matter and antimatter, is by its own a breakthrough result. The different behavior of particle and antiparticles is a possibility contemplated in the Standard Model describing the fundamental particles. CP violation with leptons is described by a fundamental parameter, the phase angle δCP which is the parameter measured at the T2K experiment. There is no specific prediction of the value of this angle in our theoretical models. Its determination is important to advance in the understanding of the standard model. CP violation is related to flavor-changing mechanisms in the standard model, its measurement may help to understand more deeply the flavor dynamics. Flavor is what physicists identify with the differences between the three lepton families (electron, muon, and tau) or the three quark families. CP violation is a known phenomenon in processes involving quarks since the 1960’s. It has taken the particle physics community almost 60 years to start seen similar behavior in leptons. I believe this is the most relevant implication of the T2K result.
Besides the relevance to particle physics, CP violation might have implications in the understanding of our matter-dominated Universe. The existence of CP violation mechanism is one of the three conditions proposed by Andrei Sakharov to explain the baryon(or matter) asymmetry of the Universe. Baryon number violation and interactions out of thermal equilibrium are the other two. CP violation is then a necessary condition although not a sufficient one. The CP violation amount and its origin are relevant to model this asymmetry. I would like to stress that we are still far from understanding this mechanism, the baryon number violation has not been proved experimentally so far, and it is not obvious that the CP violation in neutrinos and quarks are the mechanisms required to explain the baryon asymmetry in the universe. Although some theoretical models connect both phenomena, there is a long way to go. Hopefully, the new results can help in this challenging enterprise.
Can you explain the measurement principles of T2K?
The observed electron neutrino (left) and electron antineutrino (right) candidate events with predictions for maximal neutrino enhancement (red, long dash) and maximum antineutrino enhancement (blue, short dash). Credit: the T2K experiment
T2K collaboration studies the so-called neutrino oscillations. The neutrino oscillation is a quantum mechanical interference caused by the fact that every neutrino of the type electron, muon, or tau is a combination of three neutrino masses. The neutrino type electron, muon, or tau is determined by the associated heavy lepton (electron, muon, or tau) in the interaction. The neutrino has three paths to travel from the production to the interaction points. Each one associated with one neutrino mass. The neutrinos travel as a superposition of these three states, each one with a different mass and speed, producing the interference patterns. Experimentally, this quantum mechanical interference is measured by looking at the appearance of types of neutrinos at the interaction point different from the ones that were produced. Particularly in T2K, we look for the transformation of muon neutrinos into electron neutrinos. The CP phase induces differences in the oscillation for the neutrinos and its antiparticles, the antineutrinos. In T2K, we have measured the oscillation parameters for neutrinos and antineutrinos and from the difference, we can infer the value of the CP violation phase. The T2K experiment can produce both neutrinos and antineutrinos simply by focusing or defocusing positively charged pions and negatively charged pions. The positive pions produce neutrinos during its disintegration and negative pions produce antineutrinos.
Your experiment is sensitive to the δCP Phase, which parameter space can you exclude and what does this mean?
The arrow indicates the value most compatible with the data. The gray region is disfavored at 99.7% (3σ) confidence level. Nearly half of the possible values are excluded. Credit: the T2K experiment
The result from T2K excludes half of the possible values of δCP, particularly the positive values of the phase angle are excluded with a confidence level of 99.7%. If we take possible values of δCP from -180 degrees to 180 degrees we excluded values from -1.7 degrees to 164.6 degrees. This is the first time we have measured experimentally this fundamental parameter in the Standard Model.The other important read of the T2K results is that the most probable value of the δCP is close to -90 degrees implying the maximal violation of the CP symmetry in neutrinos. The fact that it can be maximal open possible ways to understand the mechanism that differentiates neutrino mass states from flavor states.
What are the consequences of the constrain of T2K on the δCP in the neutrino sector on the matter-anti-matter asymmetry?
When confirmed, the result might have several implications. First of all, it is a new source of CP violation beyond the traditional one in the quark sector. This additional source plus the special properties of neutrinos might explain through a relevant theory the origin of the matter-dominated Universe through theoretical models. Another relevant implication is related to the value of δCP. If the result is confirmed to be maximal as suggested by T2K, this might have theoretical implications since it might be a reflection of hidden symmetries in a model.
What are your ideas to further improve the measurements?
In particle physics, 99.7% is not sufficient to claim a discovery. We need values of the confidence level of 99.9999%. To reach this precision we need more data, the 115 events collected by T2K are not enough. To achieve larger statistics there are few venues we are taking. The first one implies running longer time, the second to increase the flux of neutrinos, and third to increase the mass of the far detector. The first step is just time and money, we will keep running a few years more hopefully doubling or tripling the number of neutrinos we detect. The second step can be done by increasing the total number of protons we can accumulate in the accelerator per unit of time. Protons produce the pions that subsequently produce neutrinos by decay. There is already an approved project that will almost double the number of protons during the next years. The third one requires new detectors. Recently, the upgrade of the T2K far detector, SuperKamiokande, was approved by the Japanese authorities. The new project, HyperKamiokande, will increase the detector mass and the number of detected neutrinos per unit of proton in the accelerator by almost a factor of ten. With this increase, we can accumulate ten times more neutrinos for the same number of protons than we do today. Unfortunately, this will not be sufficient. In parallel, we need to understand some of the uncertainties of the experiment. These uncertainties are related to better control of the neutrino flux predictions and the modeling of neutrinos interacting with nuclei. Both are at the moment the most relevant non-statistical uncertainties in the measurement and they will become dominant when we increase the number of detected neutrinos. To address these issues, we need supporting experiments to help to understand the production of pions by proton interactions and to improve the understanding of neutrino interactions. We also need to develop more precise theoretical models describing the interaction of neutrinos with nuclei so we can interpret these experiments correctly, and in parallel, we need to prove experimentally they are correct.
We would like to add a short comment by Silvia Pascoli in which she discusses the results of the T2K experiment in a theoretical context. We asked her about the connection between T2K results and the baryon asymmetry of the Universe.
A simple assumption, justified by cosmological inflation, is that the Universe at the very beginning contained the same amounts of matter and antimatter. In the 60’ A. Sakharov identified the conditions which are required for some process in the Early Universe to generate a small asymmetry between matter and antimatter: the violation of the C and CP symmetry, lepton (or baryon) number violation, which is testable in neutrino less double beta decay, and the out of equilibrium condition.
Leptogenesis, using leptonic CP violation, is among the favourite explanations of the baryon asymmetry as it takes place in models which have been proposed to explain the observed neutrino masses. Under certain conditions, specifically in see-saw type I neutrino mass models, it has been shown that the leptonic CP violating delta phase searched for in long baseline neutrino oscillation experiments can be the source of the observed matter-antimatter asymmetry. This is a highly non-trivial statement as in many other models the baryon asymmetry that can be generated is too small.
Observing leptonic CP violation and the violation of lepton number would provide circumstantial evidence (although not a proof) towards leptogenesis as the origin of the matter-antimatter asymmetry of the Universe.
We asked her to further comment on the connection to neutrinoless double beta decay.
First of all, as I discussed above, lepton number violation is one of the three key criteria for leptogenesis to explain the baryon asymmetry of the Universe. Neutrino less double beta decay is the most sensitive test we have of this global symmetry of the Standard Model. Moreover, the results of T2K and NOvA and other neutrino oscillation experiments on the ordering of neutrino masses play a key role in the predictions for the lifetime of the decay process. So, mass ordering information is very important to plan the future program in this field and to interpret the results from future experiments.
Federico Sanchez graduated at the Univ. of Sevilla and got his PhD at the Universitat Autònoma de Barcelona working at an experiment at CERN. He worked as a researcher at DESY and at the Max Planck Institute fur Kernphysik in Heidelberg where he acted as co-physics coordinator of the HERA-B experiment. He has worked at several particle physics experiments such as ALEPH and LHCB at CERN or HERA-B at DESY.
In 2002, he joined the K2K experiment in Japan and since then he was working on neutrino physics as the leader of the group at IFAE. He participates in the T2K experiment in Japan from almost the very beginning. In 2016, he was one of the researchers awarded the Breakthrough prize on fundamental physics which was given to the K2K and T2K collaborations for the experimental establishment of neutrino oscillations. Between 2007 and 2011, he was a member of the Nemo and SuperNemo collaborations and contributed to the preliminary ideas of the NEXT experiment.
In August 2018, he moved as a professor at the Université of Genève to take the responsibility of the group dedicated to neutrino physics at the T2K and HK experiments. In April 2019, Federico was elected International Co-Spokesperson of the T2K collaboration.
In the U.S., the Snowmass 2021 process will take place over the next year. Organized by the Division of Particles and Fields (DPF) of the American Physical Society (APS), this process is intended to define the most important questions for the particle physics community and to identify the most promising ways to address these questions in a global context. Snowmass provides an opportunity for the entire HEP community to come together to identify and document a vision for the future of particle physics in the US and its international partners. Given the increasing importance of interdisciplinary work, a strong participation of related fields such as astrophysics, cosmology, gravity, nuclear physics, accelerator physics, AMO and materials science is expected.
Between autumn 2020 and summer 2021 there will be a series of preparatory meetings and workshops organized by Snowmass conveners from ten frontiers (energy, neutrino, rare processes & precision, cosmic, theory, accelerator, instrumentation, computation, underground facilities, and community involvement).
The Frontier Conveners are nominated by the community and selected by the DPF Executive Committee plus members of the chair lines of Division of Astrophysics (DAP), Division of Physics of Beams (DPB), Division of Nuclear Physics (DNP) and Division of Gravitational Physics (DGRAV). Their first task is to identify topical group conveners. This process was developed in order to provide a diverse and representative leadership including junior and senior researchers, theorists and experimentalists, and balance regarding gender, geographical distribution, and background.
Besides there is the Steering group, which consists of the DPF Chair line and one representative each of the related units DAP, DPB, DNP, and DGRAV. This Steering group oversees the process and meets regularly with the Frontier Conveners. An inclusive Advisory Group is consulted on major decisions, and consists of the Steering Group plus the rest of the DPF Executive Committee (members at large, secretary/treasurer, and councillor), an editor, a communication liaison, and a set of International Advisors.
One of these International Advisers is Berrie Giebels as representative for APPEC.
Berrie Giebels, APPEC representative in the Snowmass 2021
Berrie Giebels defended his dissertation in 1998 and was a research associate at SLAC for 3 years. Since 2001 he is physicist at CNRS in the field of high energy astroparticle physics (Fermi, HESS, CTA). Since 2016 he is IN2P3/CNRS deputy director in charge of the astroparticle physics & cosmology perimeter including the large research infrastructures (EGO-Virgo, CTA, LSST, KM3NeT, Auger,..).
„The Snowmass Process, while essentially aimed at developing a vision for the future of particle physics in the U.S., is also a very inclusive process – thematically, integrating other fields of research such as astroparticle physics, and geographically, through the inclusion of the international community in its advisory group. Participating to this process as a European scientist is a unique opportunity to reach beyond our currently closed borders and reaffirm that research in physics relies on worldwide cooperation and collective goals. The APPEC roadmap objectives and priorities should provide valuable insights to shape the Snowmass 2021 vision, which will in return have an influence on the next European Astroparticle physics strategy update.“ – Berrie Giebels
To optimally engage all participants in the process, the Division of Particles and Fields invites the international community to submit written documents. Given the increasing importance of interdisciplinary work in related fields such as astrophysics, cosmology, gravity, nuclear physics, accelerator physics, AMO, and materials science, members of the Divisions of Astrophysics, Gravitational Physics, Nuclear Physics, Physics of Beams and members of other units with a connection to particle physics are strongly encouraged by the DPF Chair, Young-Kee Kim to participate in this process:
Letters of Interest (submission period: April 1, 2020 – August 31, 2020)
Letters of interest allow Snowmass conveners to see what proposals to expect and to encourage the community to begin studying them. They will help conveners to prepare the Snowmass Planning Meeting that will take place on November 4 – 6, 2020 at Fermilab. Letters should give brief descriptions of the proposal and cite the relevant papers to study. Instructions for submitting letters are available at https://snowmass21.org/loi. Authors of the letters are encouraged to submit a full writeup for their work as a contributed paper.
Contributed Papers (submission period: April 1, 2020 – July 31, 2021) Contributed papers will be part of the Snowmass proceedings. They may include white papers on specific scientific areas, technical articles presenting new results on relevant physics topics, and reasoned expressions of physics priorities, including those related to community involvement. These papers and discussions throughout the Snowmass process will help shape the long-term strategy of particle physics in the U.S. Contributed papers will remain part of the permanent record of Snowmass 2021. Instructions for submitting contributed papers are available at https://snowmass21.org/submissions/.
The Snowmass homepage (https://snowmass21.org) provides you further information on the current status of Snowmass 2021.
From February 17 to April 10, two new clusters of optical modules were installed, the sixth and the seventh, at Baikal-GVD Deep Underwater Neutrino Telescope. The effective volume of the facility, corresponding to the detection of hadronic showers produced by neutrinos, reached 0.35 km3.
Credits: B. A. Shaybonov
The Baikal-GVD Neutrino Telescope is designed for detecting and studying high-energy neutrino fluxes from astrophysical sources. Scientists plan to explore the astrophysical processes with huge energy releases occurred at the time when the Universe was hundreds of millions or billions of years younger.
According to the project, the volume of the facility in Lake Baikal should be about one cubic kilometer. The installing of the two new clusters in 2020 was an important step towards this goal. The effective volume of the facility, corresponding to the detection of neutrino produced showers, reached ~ 0.35 cubic kilometer. The estimates, based on existing algorithms (which are constantly improving), suggest that the current setup should be able to detect 3-4 neutrino interactions per year with the neutrino energy exceeding 100 TeV.
The Baikal Neutrino Telescope, being still under construction, is a unique scientific facility, one of four pillars of the Global Neutrino Network (GNN), along with IceCube at the South Pole, KM3NeT and ANTARES in the Mediterranean Sea. They explore all together the Universe considering neutrinos as messengers.
The installation site of the Baikal Neutrino Telescope is 3.5 km away from the shore. The facility is assembled at the depth of 750-1300 m in the Southern Hollow of Lake Baikal from about one-meter-thick ice surface, what greatly simplifies the installation.
Credits: B. A. Shaybonov
This year, the expedition met hard times because of anomalous weather conditions. During the ice formation period, a strong wind broke the ice cover of the lake. Huge ice blocks and ridges grew all across the lake, which significantly impeded the mounting. Nothing like that was observed in the whole 40-year-long history of the Baikal expeditions. It was not clear whether the team would be able to cut the ice through all these ice ridges to lay the cables to the new facility.
Thanks to a great experience of the team, the appropriate solution was found and the two new clusters were installed. In addition to them, an experimental technological string with five calibration laser light sources and underwater fibre-optic cables for data exchange was mounted. At present, all devices are successfully taking data.
Credits: B. A. Shaybonov
In total, 60 researchers, engineers, technicians, workers, including volunteers, participated in the expedition. The 2020 expedition program has been fully completed.
This year, the International Scientific Baikal-GVD Collaboration comprises the Institute for Nuclear Research of RAS (Moscow), the Joint Institute for Nuclear Research (Dubna), Irkutsk State University, Nizhny Novgorod State Technical University, St. Petersburg State Marine Technical University, the Institute of Experimental and Applied Physics of Czech Technical University in Prague, the Faculty of Mathematics, Physics and Informatics of Comenius University in Bratislava (Slovakia), the Institute of Nuclear Physics of the Polish Academy of Sciences (Krakow, Poland), EvoLogics GmbH (Berlin, Germany).
The expedition was organized by the Institute for Nuclear Research of the Russian Academy of Sciences (Moscow) and the Joint Institute for Nuclear Research (Dubna).
G.V. Domogatsky, spokesman of the Baikal-GVD Collaboration
A prototype unit in its final configuration at Elemaster.
Credits: MVM Collaboration
The first five pre-prototype units at Elemaster. Credits: MVM Collaboration
The rapid spread of COVID-19 has shown a scarcity of ventilators compared to the number of patients. Thus, on the initiative of Cristian Galbiati (GSSI and Princeton University) with Art McDonald (Queen’s University), the MVM Milano Mechanical Ventilator project has been launched. MVM is an innovative device for assisted breathing, based on an open access design, and widely available components for its easy large-scale production. MVM was born within the collaboration of GADM (Global Argon Dark Matter), engaged in experiments on dark matter at the INFN’s Gran Sasso Laboratories in Italy, and SNOLAB in Canada. The expertise in sophisticated experimental apparatuses for research in astroparticle physics has allowed the development in the field of complex control systems of gases, similar to those used in lung ventilators.The project has the support of groups from universities and research institutes in Europe, Canada and USA. Bringing the MVM ventilator to patients requires a collaboration that goes beyond the field of particle physics. Thus, scientists , clinicians and companies such as Elemaster collaborate on the project. Members of the MVM International Collaboration have activated a crowdfunding campaign.
— CANCELLED/POSTPONED, please check the website of the event for further information —
RICAP-20 will be the eight edition of the RICAP Conference and will take place from June 30th to July 3rd, 2020 in Roma, Italy. The acronym stands for Roma International Conference on Astro-Particle physics, the Conference is entirely dedicated to the study of high energy cosmic rays and it is organized by the three public Universities of Roma (University “Roma Tre”, University “La Sapienza” and University “Tor Vergata”). These Institutions provide both theoretical and experimental contributions, and participate to major experimental projects in the field (AGILE, AMS, ANTARES, ARGO, Auger, CTA, Fermi, JEM-EUSO, KM3NeT, NEMO, PAMELA,…). The Conference is held every two years and in 2020 will be held at the Physics Department of the University “La Sapienza”.
The aim of the Conference will be to present and discuss some of the most relevant theoretical and experimental results in the field of high energy cosmic rays (gamma, neutrinos, charged cosmic rays). Special attention will be paid to the multi-messenger search for high energy cosmic rays sources, including gravitational wave searches. A special session will be dedicated to Dark Matter search. The Conference will give the opportunity to collect experimental results from presently operating experiments. Experiments in progress and future projects will be discussed, debating on the different features and on sensitivities. Particular relevance will be given to the discussion of the open questions in high energy Astroparticle Physics
— CANCELLED/POSTPONED, please check the website of the event for further information —
The 16th Patras Workshop on Axions, WIMPs and WISPs will be held in Trieste (Italy) from 20 to 26 June 2020. The nature and composition of Dark Matter and Dark Energy are two of the most pressing mysteries of frontier physics, and research in these fields is presently gathering increasing momentum and attracting the efforts of scientists from many international institutions. The “16th Patras Workshop on Axions, WIMPs and WISPs” is the latest event in an annual series of conferences, started in 2005 at CERN. This workshop is aiming to continue the rich and successful series, reviewing recent theoretical advances, laboratory experiments, novel ideas as well as astrophysical and cosmological results in the fields of axions, WIMPs and WISPs. Participation by young scientists is strongly encouraged.
The European Consortium for Astroparticle Theory (EuCAPT) invited all scientists (PhD students, postdocs, and staff) affiliated to a European institution, and active in Theoretical Astroparticle Physics and Cosmology, to participate in the “1st EuCAPT census” by filling an Indico registration form. 660 scientists responded to this call and completed the census between January 13 and 31, 2020. This number shows the strong interest in Europe-wide coordination of Theoretical Astroparticle Physics and Cosmology. The data collected offer a first snapshot of the research interests of the Astroparticle and Cosmology theory community. The key-findings are summarized here.
In total 55 nationalities are represented, with more then half from four countries: UK, Italy, Spain and Germany. These are also the countries where around half of the scientists are working. We note however that the geographic and topic distribution might be biased by the channels used to advertise the census. Looking at the positions, the majority of registrants are currently faculty members. EuCAPT will make an effort to reach out to younger scientists and encourage them to join. EuCAPT will also try reach out to those communities which appear under-represented in the census, in particular low-energy neutrino astronomy and nuclear astronomy. The percentage of female scientists is only 20%, a disappointing result that however appears consistent with data from the American Physical Society and the UK Institute of Physics, and thus probably reflects the actual gender distribution in our community.
EuCAPT will now effectively start the process of consolidating and coordinating the relevant scientific community.
Part of the activities of EuCAPT is a monthly virtual colloquium which will start on March 3. The following presentations are already planned:
March 3, 11 am – Joachim Kopp
April 7, 11am – Samaya Nissanke
May 5, 11am – Licia Verde
Further information and details on how to connect will be announced on the EuCAPT website.
There will also be an annual symposium, the first one to be held at CERN from September 30 to October 2. For more details see: https://indico.cern.ch/event/853904/
We encourage those who have not completed the census but want to be informed about EuCAPT, to sign up at https://www.eucapt.org/census
Interview with Marco Cirelli, Caterina Doglioni, Gaia Lanfranchi and Florian Reindl
In October 2019 the first Joint ECFA – NuPECC – APPEC Seminar (JENAS) took place in Orsay, close to Paris, where a call has been issued for novel Expressions-of-Interest. Following this call a group of Dark Matter scientists have drafted an open EoI to gather the broader dark matter community. Among others (see full list here), Marco Cirelli, Caterina Doglioni, Gaia Lanfranchi and Florian Reindl initiated the “Initiative for Dark Matter in Europe and beyond: Towards facilitating communication and result sharing in the Dark Matter community (iDMEu)”. In this interview they present their ideas and aims for this EoI.
You are working in various countries and experiments. Where and how did you come up with the idea for the EoI?
Florian: The idea of this EoI was born at the JENAS meeting, which took place in October last year in Orsay.
Marco: Yes, although I knew many of my colleagues from previous meetings, the JENAS workshop was just the concrete occasion that allowed us to meet in person and the idea of an EoI to emerge.
Florian: The main spirit of this meeting was the wish to strengthen the bonds between the different communities, working on fundamentally different approaches to detect DM (e.g. direct, indirect and collider searches, but also fixed-target, beam-dump and dedicated axion/ALP experiments). We are all working on dark matter in different countries, for different experiments and in different communities, but agreed that even in the dark matter community a common “platform” to share ideas, data etc. is missing. This was the starting point which evolved in the EoI.
Caterina: We see this EoI as a platform to bring together different existing efforts. An effort is, for instance, the LHC Dark Matter Forum / Dark Matter Working Group, where LHC theorists and experimentalists are connecting LHC results on WIMPs to direct and indirect detection experiments. In the LHC community there is also a growing wish to expand the DM menu beyond WIMPs, both conceiving new models and finding new experimental signatures.
Gaia: When we first discussed in Orsay, I immediately understood the importance of the initiative and I supported it. For me it represents the natural evolution of my activity within the Physics Beyond Colliders (PBC) study group. The PBC was launched by the CERN management in 2017 with the aim to investigate the potential of the CERN accelerator complex and scientific infrastructure for projects aiming to answer the same fundamental questions as those at colliders but requiring a different type of beams and experiments. To investigate the nature of DM beyond the WIMP paradigm was already part of this effort. The PBC study group gathered together colleagues from collider, beam dump, fixed target, axion/ALP experiments, and astroparticle to explore synergies and complementarities of different theoretical and experimental approaches.
What are your aims and how you want to realize them?
This image shows the galaxy cluster Abell 1689, with the mass distribution of the dark matter in the gravitational lens overlaid (in purple).(Credit: NASA, ESA, E. Jullo (JPL/LAM), P. Natarajan (Yale) and J-P. Kneib (LAM))
Florian: Nowadays, dark matter is commonly accepted as one of the fundamental open questions of physics. Therefore, we see the community quickly growing and approaching the dark matter problem from very different angles experimentally like theoretically. The result is a very active and lively, but also very diverse community. The idea of the EoI is to bring all those people together to take full advantage of all we “know” about dark matter already and to also make full use of cross-links for future work. The EoI is intended to show that there is a broad interest of the actors in the field to actually do this. It is also meant as a basis to jointly work on a concrete implementation.
Gaia: The origin and nature of DM is one of the deepest mysteries in particle physics today and we need to attack this problem from different fronts. Theory wise, we need to understand which other relevant hypotheses about the DM nature should be considered beyond the standard WIMP paradigm and how these hypotheses fit into a general theory framework. Two prominent examples are, for example, axions with masses in the micro-eV range or light DM with thermal origin in the MeV-GeV range. Experiment wise, we need to identify synergies and complementarities across different experimental approaches in order to enlarge the exploration as much as possible while optimising resources. In order to pursue these goals, first of all we need to develop a “common language”, which means to identify a common theory framework: theoretical and experimental physicists need to talk together in order to identify motivated benchmark models which could be tested experimentally. A first step in this direction was done within the Physics Beyond Colliders activity and allowed us to put together results from a wide variety of experimental efforts. This framework could be further improved with the help of the particle and astroparticle theory community and more experimental results can be included.
Caterina: Because we know so little about the nature of dark matter, I am keen to try to keep pursuing it from all directions. My own direction is the LHC, and I want to collaborate as much as possible with all others, experimentalists and theorists, who can point the community in the most promising directions towards a discovery. Since one of my passions at work is data acquisition and computing, I am also keen to connect the work of this initiative to that of the HEP Software Foundation, which facilitates collaboration and sharing of software; and to the ESCAPE project, a multi-collaboration effort across particle and astroparticle physics that aims to establish a collaborative cluster of scientific infrastructures that work together on Open Science implementations of our research tools.
Marco: I am a theorist, so I don’t work in any specific experimental collaboration. But as a theorist, I pay a lot of attention to results achieved by my experimental colleagues. The search for Dark Matter in recent years has literally boomed and expanded in a myriad of interesting directions, with many new theory ideas (at different mass scales, embedded in different frameworks or simply standalone) and many new experimental setups (ranging from tabletop to full-fledged international collaborations). This ‘explosion’ is of course positive and incredibly exciting, but also needs to be somewhat framed and patterned in order to be more efficient. To realize this, we want to rely on the work already produced in the different communities. We want to act at the ‘human relations’ level (conferences, meetings, cross-talks) and at the technical level (online repositories, sharing of results, common services).
You already have more than 200 endorsers. Do they represent the Particle-, Astroparticle- and Nuclear Physics Community? What are their main interests?
Florian: We have endorsers from all communities and also from experiment and theory. I would like to note that this EoI was born in Europe, but the EoI is not restricted to Europe and we find supporters all over the world. What brings us together is to solve the puzzle of dark matter.
Content of the Universe (credit: HAP / A. Chantelauze)
Gaia: Within the signatories I recognize the names of friends, colleagues, and distinguished physicists belonging to the three communities with a very broad spectrum of interests, from collider physics, to DM direct and indirect detection experiments, flavour physics, gravitational waves, and particle and astroparticle theory. I do believe that this excellent and broad mixture of different expertise will strengthen the EoI program.
Marco: In addition to the different scientific backgrounds, I can also recognize among the endorsers people at different career stages, ranging from some of the senior policy makers of the field to young postdocs and some PhD students. This, I think, is very healthy and shows the grassroots nature of the initiative.
Gaia: We are living a period of confusion in particle physics, old paradigms seem to be inadequate to answer fundamental questions, and new ones are still to be defined. Nevertheless I have seen in the last few years an increasing interest from people belonging to different communities to cross boundaries, talk together, exchange ideas and results, towards the common goal of understanding fundamental laws of Nature. Nature is the same for everyone. This EoI is the expression of an already existing and widespread movement in this direction and that is why it is getting a large support.
Marco: The diverse scientific interests and backgrounds are in a sense natural, since the Dark Matter problem is by its very nature transdisciplinary. In another sense, this also shows that many sub-communities are perhaps restructuring themselves in this period and that many colleagues that were working on other subfields are now reorienting their research towards Dark Matter.
Caterina: One of the key points of this initiative in my opinion is to be inclusive of everyone’s interests and voices. Many of these voices are already being heard in working groups where “expert work” is ongoing, such as DMWG and PBC, and we will rely on their work to set the direction and topics of the future steps. Even if we distributed the EoI link quite broadly, we may not have reached out to everyone who is interested. Therefore, this is by no means a “closed” list – we will turn this list of endorsers into a mailing list with an archive that will be on the indico page so that others can sign up along the way.
What do you expect that APPEC-ECFA-NuPECC organisations can do?
Marco: The organizations have already done a lot, just by making the interesting and highly non-trivial JENAS meeting possible, that spurted our initiative. By keeping the channels of communication open in between the communities (e.g. organizing other similar meetings, or providing logistical support to initiatives like ours) I think that these organizations can have a very positive role.
Gaia: We need help on several fronts. First of all, we need guidance from APPEC-ECFA-NuPPEC, to better understand what can be realistically done and with which priority. Second, the help of these organisations will also be invaluable to have this effort officially recognized in the Institutes of all active participants in order to:
have a framework in which this proposal can be developed;
get support for related activities (space/logistic/funding for meetings/conferences/workshops, setup of publicly accessible repositories where to store results/algorithms/webpages, etc);
improve the communication in two directions:
across the three scientific communities in order to spread information about events, discussions, and results,
towards the general public in order to convey a common message and present our research progress as a common story, as truly is.
Do you think your work can influence the EPPSU, and if not this one, maybe the next?
Group picture from JENAS-2019.
Caterina: Some of us proposing this EoI had also already worked together on the Briefing Book towards the update of the European Strategy of Particle Physics, where we wrote an “Outlook on synergies” in the Dark Matter chapter reflecting the wish for closer collaborations between the astroparticle, particle and nuclear physics in terms of common search targets and common tools (e.g. experimental technologies, shared software repositories…).
Gaia: there is already a widespread and large movement in the direction of work across theory-experiment and across different communities. This movement cannot be stopped at this stage, but certainly can be better organized. I hope that the ESPPU delegates will not miss the opportunity to further boost the already lively and rich particle, astroparticle and nuclear physics communities.
Caterina: There were already favourable steps in this direction in the 2013 strategy, which have led to the creation of initiatives such as EuCAPT, an astrophysics theory centre within CERN, whose help we’ve been relying on for the hosting of this EoI and further initiatives.
Marco: I don’t think that initiatives like ours are meant to ‘influence’ processes like the EPPSU. In some sense, we are just aiming to deal with the day-to-day business of Dark Matter research in a more streamlined way (creating links, putting in place technical tools, facilitating communication…) rather than devising the broad lines of the strategy. We are bold enough to think that Dark Matter is already a clear crucial priority of our field, and we would like to make the process of searching for it more efficient.
Caterina: This EoI is meant to encourage communication within a platform that will help DM researchers in Europe and worldwide, and will have useful practical outcomes such as common repositories and shared outreach material.
What will be the next steps?
Florian: We have some next steps sketched at our indico page. I think the most important one is a kick-off meeting organized at CERN (with an available remote connection), which will be followed up by meetings at upcoming conferences and workshops.
Marco:The kick-off meeting will be an occasion to further understand the work that is already being done in many working groups aimed at structuring DM searches in different subfields. Then we will discuss the next steps with the community of endorsers.
Florian: We also plan to establish a common repository to share experimental data (or use existing repositories) coming along with frameworks for their theoretical interpretation. Also, we will from the beginning work together on public outreach, such as e.g. the international dark matter day.
Gaia: My personal opinion is that in a first stage we should rely on existing activities and facilitate communication among them. As far as I am concerned, I will further boost the work done within the Physics Beyond Colliders study group during the workshop FIPs 2020 organized at CERN in May 2020. At this meeting, we will discuss, among other topics, results and prospects for light DM and axion searches with a wide variety of experimental techniques and with the help of renowned theoretical and experimental experts in these fields. I know that a similar effort is being done within the DM@LHC workshop and I have been invited to their annual meeting in June 2020 at DESY to discuss possible synergies. We hope to be present at the APPEC, ECFA and NuPPEC town meetings and to establish an annual meeting of iDMEu.
Further reading:
Initiative for Dark Matter in Europe and beyond iDMEu
Marco Cirelli is a senior CNRS researcher at the Laboratory of Theoretical and High Energy Physics (LPTHE) of Sorbonne University, in Paris. He obtained his PhD from Scuola Normale Superiore of Pisa, Italy, in 2004 and subsequently worked at Yale University, Saclay and CERN. From a background as a particle theorist, he slowly drifted towards astroparticle theory and cosmology. His interests have been revolving around the issue of Dark Matter for the past 15 years. In particular he focuses on searches using charged cosmic rays (positrons, antiprotons, antinuclei), high-energy gamma rays and neutrinos. From 2012 to 2018 he has led the ERC project “NewDark” (New Directions in Dark Matter Phenomenology at the TeV scale).
Caterina Doglioni
Caterina Doglioni is a senior lecturer at Lund University (Sweden). She completed her PhD on QCD physics at the ATLAS experiment at the LHC in 2011 in Oxford. Her interest in physics beyond the Standard Model and Dark Matter was developed during her postdoctoral research position at the University of Geneva (2011-2015) and subsequently at Lund University (2015-now). She is the PI of the DARKJETS ERC Starting Grant, and she is supported by the Swedish Research Council. Throughout her career, she has been driven by finding out more about the constituents of matter as well as by the challenges related to the “big science” needed to study them. The Large Hadron Collider is the perfect scientific environment to combine the two: with her group and colleagues she works on the challenges that a data-rich research environment presents for discoveries of rare processes at ATLAS (more information about dark matter at ATLAS). She has been one of the Dark Matter Forum and Dark Matter Working Group organizers from 2014 to 2018, and ATLAS Astroparticle Forum convenor from 2016 to 2018. She is currently the chair of the Swedish Physics Society Board for Particle and Astroparticle Physics, a member of the coordination team of the HEP Software Foundation (HSF), as well as HSF trigger and reconstruction working group coordinator.
(Photo credits: Lena Björk Blixt)
Gaia Lanfranchi
Gaia Lanfranchi is a senior researcher at the Laboratori Nazionali di Frascati of the INFN.
After about 15 years of activity in flavor physics within the LHCb collaboration where she had several roles of coordination and responsibility, in 2014 she moved her scientific interest towards the study of feebly-interacting hidden sectors. She has been convener of the Beyond the Standard Model (BSM) working group of the Physics Beyond Colliders activity at CERN and member of the BSM @ Colliders working group of the Physics Preparatory Group which provided input to the current European Strategy for Particle Physics update. She is one of the proponents and project leader of the muon system of the SHiP experiment proposed at the Beam Dump Facility at CERN.
Florian Reindl
Florian Reindl is a researcher at the Technical University Vienna and the Institute for High Energy Physics (HEPHY) Vienna. He finished his PhD in 2016 in Munich (Max-Planck-Institute for Physics and Technical University) and worked at INFN Rome, before moving to Vienna. Since the beginning of his career he has been working in data analysis for the CRESST direct dark matter detection experiment serving as the CRESST analysis coordinator since several years. The main focus of his recent work was to explore very light dark matter particles. He is an initiator and the spokesperson of the COSINUS project which is currently under construction at the LNGS underground laboratory. COSINUS is based on CRESST low-temperature technology and aims to clarify the long-standing dark matter claim of the DAMA collaboration. The biggest event for Florian in 2020 will be to chair the identification of dark matter (IDM) conference in Vienna.
Over the past year, the Scientific Advisory Committee (SAC) received mandate from the General Assembly to form a Dark Matter (DM) Direct Detection sub-committee, which is now ready to begin its work.
How to detect Dark Matter (credit: HAP / A. Chantelauze)
It is chaired by Leszek Roszkowski, who is supported by 12 experts from different fields covering relevant aspects of direct detection such as experiments targeting axion searches, LAr and LXe experiments, scintillating crystals, CCDs, theory and astronomy and cosmology connections, as well as connections with collider measurements.To aid in the discussions and to formulate concrete recommendations for the experimental effort in direct DM detection for the next decade, the DM Direct Detection committee is expected to provide an assessment of current and future scientific opportunities in non-accelerator DM searches, and to summarize the results in a written report.
The final report is expected to include:
The global context of DM particle searches, including the existing hints or evidence for DM particles, an inventory of alternatives for the particle nature of DM, and an inventory of present and best estimates of foreseen sensitivities of various techniques and how they compare to other than direct detection methods.
An inventory of existing DM experiments, with focus to Europe, and the technologies adopted by these, with current most competitive results.
A comparative SWOT analysis of existing, planned and proposed technologies for DM direct detection with the potential to surpass current sensitivities in the next decade with the eventual goal of reaching or surpassing the so-called neutrino floor.
An assessment of the required infrastructure in Europe, including maintenance and upgrades of existing facilities.
A list of likely technological and scientific synergies between the different direct detection technologies and with research and R&D outside of the field.
An inventory of physics, astronomy or other research that can be done in addition to DM direct detection with the various technologies. In addition, it would be important to discuss if such other research can be done even within the specifically proposed DM experiments. Synergies with other experiments of indirect, accelerator and cosmology DM searches should also be considered, including possible technical and R&D synergies, e.g. with CERN, other laboratories and industry.
Any other recommendations within the scope of DM direct searches, that the committee deems relevant.
The report is expected to be a useful and valuable resource not only for experts but also for a wider community of astroparticle physics and related research areas. It would therefore be welcome if the broader implications of low background physics and the search for rare events could also be discussed, as well as the relevance of the programme for the training of the next generation of researchers.
— CANCELLED/POSTPONED, please check the website of the event for further information —
The 27th European Cosmic Ray Symposium (ECRS 2020) will be held in Nijmegen, the Netherlands from July 13th to 17th, 2020.
The European Cosmic Ray Symposium is covering the following topics in Astroparticle Physics:
Cosmic-Ray Physics, Gamma-Ray Astronomy, Neutrino Astronomy, Dark Matter Physics, Solar and Heliospheric Physics, Astroparticle Physics Theory and Models as well as Experimental Methods, Techniques, and Instrumentation.
The scientific program will include invited plenary talks, solicited presentations in parallel sessions, and poster sessions. There will be awards for the best posters.
The European Consortium for Astroparticle Theory (
