Prof. Yahya Tayalati

An Unflagging Collaborator

Prof. YahYa Tayalati; an Intimate Profile

In the realm of experimental particle physics or high-energy physics, everything is oversized, sophisticated, and of course, expensive. A handful of countries can afford such large-scale infrastructures needed for running experiments in this field. Usually, developed countries or a consortium of them participate in the construction of the research infrastructure.

However, in 2017, thanks to the efforts of a dedicated physicist Morocco found a place among the leading countries that have a vital role in a large-scale international project: Cubic Kilometer Neutrino Telescope (KM3NET). The contribution of the Moroccan team, led by Prof. Yahya Tayalati from the University Mohammed V in Rabat, is not only for the scientific exploitation but also for the project construction, which is entirely new. That was for the first time that a Moroccan - and even African - team contributed to constructing a particle detector.

This unprecedented cooperation with the Moroccan team was partly due to Tayalati’s background with Antoine Kouchner, spokesperson for the Antares Collaboration and coordinator of the ORCA-KM3NET project in the 2000s. “I have known Prof. Tayalati for a very long time since he had come to France to do part of his studies during his doctoral thesis. This is how we met. We were both in the thesis together,” says Kouchner. The other reason behind this success was Tayalati’s doctoral thesis which he did on the ANTARES project – the KM3NET predecessor – at the same time with Kouchner. Then afterward, they parted ways, and each lived their own scientific adventures. However, they remained in contact, and the idea of this cooperation came to life through their connection.

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Tayalati already had the right expertise on the ANTARES project that he had acquired during his doctoral stay in France. “I have started my career as an experimental high-energy physicist with a Ph.D. degree from the University of Mohammed First, Oujda, Morocco,” he says. At the time, he proposed a solution to one of the problems in neutrinos physics. The first group of Oujda that joined the collaboration did not participate in constructing the first ANTARES project. But they participated in analyzing data in a specific sector related to the research of new physics. “I have been involved in the early preparation and deployment of the ANTARES telescope, and my effort allowed Morocco to join this international collaboration in 2011 officially. Since then, several students graduated with the ANTARES project,” Tayalati says

The under-construction KM3NET research infrastructure, which will be deployed at the bottom of the Mediterranean Sea at a depth of 3 kilometers, will host the next generation of neutrino detectors as part of a world effort to detect dark matter. This is the most important scientific collaboration in which Morocco was involved. “I convinced three universities in Morocco – The University Mohammed First in Oujda, The Cadi Ayyad University in Marrakesh, and my University in Rabat – to join KM3NET collaboration and to form an Astroparticle cluster in Morocco,” Tayalaty says.

Even before the ANTARES KM3NET, Tayalati had a great experience in working with extensive collaborations. After his thesis work, he began his career in ATLAS, one of the most significant collaborative efforts ever attempted in science, with over 5500 members, including physicists, engineers, technicians, students, and support staff worldwide. “My involvement with the ATLAS experiment at CERN (European Organization for Nuclear Research) includes more than 20 years of my career,” he says. The complexity of the underground ATLAS detector requires a tremendous amount of effort from all members of the collaboration. Operating the apparatus, collecting the data, and analyzing them involve almost everybody in this collaboration to different degrees. Each member in ATLAS has a direct or indirect contribution to every scientific publication, which has nearly 3000 scientific authors. “In the end, you feel you are always contributing to the overall ATLAS achievements,” he says.

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What Tayalati has been doing through his career is much different from his childhood dream about his future profession. “I was fascinated by airplanes; I dreamed of being a pilot one day,” he says. “Like all Moroccans from my generation, I used to spend all weekend playing with my friends until late hours outside my parents’ home.” With no internet, computer games, and smartphones, they have to invent proper games with basic tools. “Some concepts of physics have a major role in those games,” he remembers. His education started in a Quranic School where he learned the first basics of rigor and discipline, two essential qualities for being successful in science as a collective enterprise. Later, in primary school, he got drawn to scientific subjects, while he was mostly interested in mathematics in high school.

Tayalati comes from a working-class family in Morocco. His father was a miner in a coal mine. “It is a tough job. He pushed my siblings and me to work hard for a better job than he had. He was illiterate but very aware of the importance of education in self-promoting. My father and the nature of his job had a big impact on me,” he says. The first time Tayalati left the country was to attend a school at ICTP (Abdus Salam International center of theoretical Physics in Trieste).

The journey had a significant impact on his life and career. It happened during the preparation of his master’s degree in one of the prestigious laboratories of theoretical physics in Morocco, which was officially connected to the ICTP. “I was very impressed by both the work of Prof. Abdus Salam on the standard model and deeply influenced by his personality,” he says. Abdus Salam’s efforts in developing sciences in the Muslim world through the different mobility programs he established at ICTP were really inspirational to him. “This was one of the major motivations that pushed me to this field.” Abdus Salam (1926-1996), a Pakistani theoretical physicist, was the only Muslim scientist who won a Nobel Prize in physics.

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Tayalati describes his efforts in teaching different aspects of high-energy physics to get more students interested in this field as his most important contribution. “I’m someone that as scientist, researcher, teacher, and parent, likes to combine all challenges and move and share my knowledge with my community for a better life,” he says. He decided to spend the monetary award of the Mustafa Prize helping his colleagues and student. “This award will come at the right time in my career to help me to get access to some materials that will be needed by the members of my group. And they will be proud to see it is going to be used for such purpose supporting the mobility of our Ph.D. students.”

In recent years, he participated in a global effort called “International Masterclasses,” aiming to prepare the next generation of researchers in high-energy physics. “Given that there is not enough information about research in the high-energy physics field, the Masterclasses usually present the first opportunity for high school students to be in direct contact with our activities,” he says. The program consists of an international day during which the more than 13 thousand 15-19 years old high school students in 60 countries come to one of about 225 nearby universities or research centers to learn what it is like being a particle physicist. “We have found that international Masterclasses usually raise a huge amount of interest among them, and many decide in the end to pursue this field,” he says

Tayalati says once he is done with research, he wants to spend time with his family. “I am proud and grateful for my family, my wife, and my kids who always support me spending hours on my research. They understand my challenges in this field and the time I devote to research and traveling outside the country. I’m grateful for their patience and support.” When it comes to his bucket list, the top priority is initiating a new collaboration. “I wish I had time to get together many scientists – theorists and experimentalists – in different fields of high-energy and Astroparticle physics to set common goals for fundamental research.”

Into the Unknown
At the world most sophisticated lab, thousands of physicists are working together to find a path beyond the standard model

What are we made up of? At the most fundamental level, one can ask the same question as what the universe is made up of. Currently, the standard model of particle physics is our best answer to the fascinating question. According to the standard model, all the matter in the universe, including galaxies, stars, planets, and even you, is made up of 25 elementary particles. The development of the standard model began in the 1960s and was completed mainly by the late 1970s. Besides the fermions and gauge bosons, there is only one more particle in the standard model: the Higgs boson, which gives masses to the other elementary particles.

Higgs boson was the last elementary particle to be discovered. However, it was proposed independently by several researchers in the early 1960s. After nearly half a century of particle-chasing, physicists hunted the elusive particle in 2012 at the Large Hadron Collider (LHC), the largest and by far the most powerful particle accelerator on earth. “By colliding protons at high energy and high luminosity, this powerful accelerator makes it possible to probe the matter on new scales and to thoroughly test the Standard Model,” says Prof. Yahya Tayalati, a physicist at University Mohammed V in Rabat, Morocco, who was involved in LHC project for two decades. The discovery slotted into place the final missing keystone of the standard model.

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Through the victorious years of particle physics, researchers in other fields of physics have also tried their hands on the foundations of reality. In the 1930s, astrophysicists realized that galaxy clusters contain a lot more mass than all visible matter combined can possibly account for. Apparently, a new type of “dark matter” was needed to explain the observations. Since then, evidence of dark matter has piled up to the point that now no one doubts its existence. Still, no one knows what dark matter is made of. Astrophysicists say it is a type of particle that has no interaction with ordinary matter, a mysterious one that neither absorbs nor emits light. However, the horrifying fact is that dark matter is five times more abundant than visible matter.

In 1998, cosmologists surprisingly discovered that the expansion of the universe is accelerating. They can mathematically show that the mysterious accelerator, called “dark energy,” is nothing but the energy carried by empty space. Besides that, there is one more thing we know about dark energy for sure: 68 percent of the total matter-energy content of the universe consists of dark energy. In other words, we are living in a universe with a composition of 68% dark energy, 27% dark matter, and only 5% ordinary matter. All our knowledge about the building blocks of the matter is limited to that 5% ordinary matter.

Despite its enormous success, the standard model leaves several fundamental questions unanswered. “A major problem with the standard model is related to the origin of dark matter and dark energy, constituting nearly 95% of the energy density of the universe, remained totally unexplained, and the standard model fails at providing a viable candidate for the observed abundance of dark matter in the universe,” Tayalati says. However, this is not the only problem with the standard model. One of the most fundamental questions left open by this model is the gravitational interaction, which is totally ignored in the description of fundamental interactions. “All this and many other arguments suggest that this model is only an effective theory of a more fundamental model manifesting itself at higher energy,” he says.

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Tayalati involvement with ATLAS, the largest general-purpose particle detector experiment at LHC, goes back to the project’s early days. He spent twenty years of his career in ATLAS, covering many topics ranging from hardware projects and detector operations to software development and physics analysis and measurements. His first involvement was the ATLAS Liquid Argon Presampler, in which he has contributed to all steps related to the construction, commissioning, and operation of this subsystem. The Presampler, which is used for photons and electrons detection, has proven to be very efficient and it is now widely used in many ATLAS physics measurements.

One of the recent achievements of Tayalati and his colleagues in ATLAS collaboration was the observation of Light-by-light (LbyL) scattering for the first time in 2019. This process is completely forbidden in classical electrodynamics but appears in quantum electrodynamics. The LbyL scattering is an extremely rare process which makes its measurement very difficult and inaccessible. Many attempts with other devices have been proposed without any success.

Regarding the ultra-peripheral high energy heavy-ion collisions at the LHC, the probability of this process gets enhanced, and researchers found an excellent opportunity to observe that. They hoped to detect the telltale signal with a simple topology of two scattered photons at the final state while the heavy ions escape the collisions. Eventually, using data collected by ATLAS, Tayalati and his colleagues reported 59 events while they expected only 12 from the background, and this was interpreted as the first observation of the LbyL scattering of photons.

They have also measured the probability of this process and what they obtained is very close to the theoretical predictions. It was a clear demonstration of how LHC can perfectly work as a photons collider. What makes this process very interesting is the fact that scattered photons could couple to any new particle, providing a promising way to probe physics beyond the standard model. “We in ATLAS explored the LbyL scattering to search for axion-like particles, which is a great candidate to dark matter. The study provides the most stringent limits to date on axion-like particle production,” Tayalati says.

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Another fundamental question left unanswered by the standard model is about the mass of neutrinos. Besides their unique properties, what makes them the favored particle for many physicists, Tayalati is no exception, are their implications on cosmology and astrophysics. Neutrinos are the messengers transmitting information from the early stages of the universe. Detection of these long-time travelers could help in the understanding of the evolution of the universe. Furthermore, measurements from neutrino telescopes coupled to gravitation waves and photons detections have opened a new area of Multi-Messengers astrophysics in recent years.

Tayalati started his career as an experimental high-energy physicist with a Ph.D. degree from the University of Mohammed First, Oujda, Morocco. At that time, he proposed a solution to one of the problems in neutrinos physics, which was the observed deficit of neutrinos coming from the sun. Later he pursued the field by involvement in the ANTARES project, a neutrino detector residing 2.5 km under the Mediterranean Sea. “I have been involved in the early preparation and deployment of the ANTARES telescope,” he says. Due to his efforts, Morocco officially joined this international collaboration in 2011. Since then several students graduated with the ANTARES project. “I was the convener of the exotic physics group and with the Moroccan students we derived the strongest experimental limits on the existence of Magnetic Monopoles,”he says.

In recent years, Tayalati has started a new collaboration with KM3NeT, which is a large research infrastructure, in construction with the technology and the knowledge acquired from its predecessor ANTARES. “I convinced three universities in Morocco to join this international effort and to form an Astroparticle cluster in Morocco,” he says. This cluster allowed launching a pilot project, M1, to set up and operate a production line of optical modules for the KM3NeT neutrino telescope in Morocco.

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Before the LHC first run, many physicists hoped that this fascinating machine would reveal some clues about what might lie beyond the standard model. However, everything seems standard so far. Tayalati believes events beyond the standard model are quite rare, so isolating and investigating those events needs a massive amount of data.

“Up to now, we have collected only 10% of data planned for the LHC program; this was sufficient to constraint or to reject many exciting theoretical models that introduce physics beyond the standard model. Certain versions of supersymmetry, for example, are less and less plausible,” he says. However, he thinks it is very early to judge the situation, and we have to wait for the subsequent runs.”

Tayalati believes the breakthrough will be “detecting a signal that can be interpreted as a candidate for dark matter or graviton. This will open a huge challenge for both experimenters and theorists to confirm such a discovery and interpret it within a universal model.”