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Farewell to the Alcatel phone exchange

Cern News - Mon, 11/03/2024 - 16:17
Farewell to the Alcatel phone exchange

On 14 February, CERN disconnected the Alcatel phone exchange, which began in 1990 (and hit the frontpage of the Bulletin at the time). This now marks the end of physical office telephones in the Laboratory, with the migration to the software-based systems – TONE and CERNphone – now completed.

“We replaced the Alcatel phone exchange, which routes calls within CERN and to outside lines, with a CERN-built exchange called TONE,” explains Tony Cass, head of the IT Communications Systems group. Last year, the TONE exchange also took over the features of the old “call centre” system that handles calls to, e.g., the Service Desk where several people respond to calls to a single number.

“The harder task,” he continues “was to build the software phone application and replace all the physical phones by software phones.”  After considering various alternatives and providers, rollout of two CERNPhone applications started at the end of 2020. Read more details in the IT README.

When CERN began in 1954, “the CERN phone directory contained everyone’s home number” as Franco Bonaudi recalls in our CERN70 series.  By 1965, just 17 phone lines served 1000 CERN extensions, with callers facing long waits. Now, as well as TONE and CERNphone for phonecalls, CERN also offers the CERN Campus App for on-site information, news and events.

katebrad Mon, 03/11/2024 - 15:17 Publication Date Tue, 03/12/2024 - 11:10

Farewell to the Alcatel phone exchange

Cern News - Mon, 11/03/2024 - 16:17
Farewell to the Alcatel phone exchange

On 14 February, CERN disconnected the Alcatel phone exchange, which began in 1990 (and hit the frontpage of the Bulletin at the time). This now marks the end of physical office telephones in the Laboratory, with the migration to the software-based systems – TONE and CERNphone – now completed.

“We replaced the Alcatel phone exchange, which routes calls within CERN and to outside lines, with a CERN-built exchange called TONE,” explains Tony Cass, head of the IT Communications Systems group. Last year, the TONE exchange also took over the features of the old “call centre” system that handles calls to, e.g., the Service Desk where several people respond to calls to a single number.

“The harder task,” he continues “was to build the software phone application and replace all the physical phones by software phones.”  After considering various alternatives and providers, rollout of two CERNPhone applications started at the end of 2020. Read more details in the IT README.

When CERN began in 1954, “the CERN phone directory contained everyone’s home number” as Franco Bonaudi recalls in our CERN70 series.  By 1965, just 17 phone lines served 1000 CERN extensions, with callers facing long waits. Now, as well as TONE and CERNphone for phonecalls, CERN also offers the CERN Campus App for on-site information, news and events.

katebrad Mon, 03/11/2024 - 15:17 Publication Date Tue, 03/12/2024 - 11:10

Superconducting stripes induced by ferromagnetic proximity in an oxide heterostructure

Nature Physics - Mon, 11/03/2024 - 00:00

Nature Physics, Published online: 11 March 2024; doi:10.1038/s41567-024-02443-x

Copper-based and iron-based compounds exhibit an interplay between magnetism and superconductivity. Now, this idea is extended to two-dimensional oxide heterostructures, where a spatially varying superconducting order is demonstrated at the EuO/KTaO3 interface.

Demonstration and imaging of cryogenic magneto-thermoelectric cooling in a van der Waals semimetal

Nature Physics - Fri, 08/03/2024 - 00:00

Nature Physics, Published online: 08 March 2024; doi:10.1038/s41567-024-02417-z

Cooling efficiency in thermoelectric devices decreases considerably at lower temperatures. Now thermoelectric cooling at cryogenic temperatures is directly imaged in a van der Waals semimetal.

Topological lasing demonstrated in the mode-locked regime

Nature Physics - Thu, 07/03/2024 - 00:00

Nature Physics, Published online: 07 March 2024; doi:10.1038/s41567-024-02421-3

The concept of temporal mode-locking has been leveraged to study the interplay between laser mode-locking and photonic lattices that exhibit non-Hermitian topological phenomena. The results suggest new opportunities to study nonlinear and non-Hermitian topological physics as well as potential applications to sensing, optical computing and frequency-comb design.

Terahertz magnon algebra

Nature Physics - Thu, 07/03/2024 - 00:00

Nature Physics, Published online: 07 March 2024; doi:10.1038/s41567-024-02427-x

Excitation of magnons — quanta of spin-waves — in an antiferromagnet can be used for high-speed data processing. The addition and subtraction of two such modes opens up possibilities for magnon-based information transfer in the terahertz spectral region.

Enabling open access to books

Cern News - Wed, 06/03/2024 - 11:46
Enabling open access to books

CERN and the not-for-profit organization OAPEN Foundation are happy to announce a further expansion of their collaboration to jointly promote open access to books.

Since 2021, CERN and the OAPEN Foundation have collaborated to disseminate books that are made available in open access through SCOAP3 for Books, a collective open-access initiative hosted at CERN.

Building on this successful track record and the aligned values and goals, OAPEN and CERN have now signed an expanded collaboration agreement whereby, from 2024 onwards, CERN will use its extensive technical infrastructure to directly host both the OAPEN Library and the Directory of Open Access Books (DOAB) in its Data Centre, alongside its other scholarly communication services such as INSPIREhep and Zenodo.

This mutually beneficial arrangement will help increase the operational efficiency and reliability of OAPEN and DOAB as vital services for the research community spanning all scholarly disciplines. “For CERN, this further amplifies its existing efforts to support and promote open science,” says Alexander Kohls from the CERN Scientific Information Service. “Utilising the CERN infrastructure will significantly increase stability for researchers worldwide allowing free and open access to the more than 30,000 books hosted in the OAPEN Library. Moreover, leveraging this infrastructure across multiple initiatives and disciplines ensures efficiency.”

Since the very beginning of both organisations, open research has been at the core of their respective missions. CERN has already successfully supported other communities in establishing or expanding open science principles and collaborates with organisations such as UNESCO, the European Commission, and NASA to further accelerate the global transition to open science. For more than a decade, OAPEN has operated three platforms dedicated to the dissemination and discovery of open-access, peer-reviewed books.

abelchio Wed, 03/06/2024 - 10:46 Publication Date Wed, 03/06/2024 - 15:00

Enabling open access to books

Cern News - Wed, 06/03/2024 - 11:46
Enabling open access to books

CERN and the not-for-profit organization OAPEN Foundation are happy to announce a further expansion of their collaboration to jointly promote open access to books.

Since 2021, CERN and the OAPEN Foundation have collaborated to disseminate books that are made available in open access through SCOAP3 for Books, a collective open-access initiative hosted at CERN.

Building on this successful track record and the aligned values and goals, OAPEN and CERN have now signed an expanded collaboration agreement whereby, from 2024 onwards, CERN will use its extensive technical infrastructure to directly host both the OAPEN Library and the Directory of Open Access Books (DOAB) in its Data Centre, alongside its other scholarly communication services such as INSPIREhep and Zenodo.

This mutually beneficial arrangement will help increase the operational efficiency and reliability of OAPEN and DOAB as vital services for the research community spanning all scholarly disciplines. “For CERN, this further amplifies its existing efforts to support and promote open science,” says Alexander Kohls from the CERN Scientific Information Service. “Utilising the CERN infrastructure will significantly increase stability for researchers worldwide allowing free and open access to the more than 30,000 books hosted in the OAPEN Library. Moreover, leveraging this infrastructure across multiple initiatives and disciplines ensures efficiency.”

Since the very beginning of both organisations, open research has been at the core of their respective missions. CERN has already successfully supported other communities in establishing or expanding open science principles and collaborates with organisations such as UNESCO, the European Commission, and NASA to further accelerate the global transition to open science. For more than a decade, OAPEN has operated three platforms dedicated to the dissemination and discovery of open-access, peer-reviewed books.

abelchio Wed, 03/06/2024 - 10:46 Publication Date Wed, 03/06/2024 - 15:00

Small version of a CERN detector could help to deliver more precise radiotherapy of head tumours

Cern News - Wed, 06/03/2024 - 10:01
Small version of a CERN detector could help to deliver more precise radiotherapy of head tumours Mária Martišíková (left), the project leader from Heidelberg University Hospital and German Cancer Research Center (DKFZ), and DKFZ researcher Laurent Kelleter. (Image: Heidelberg University Hospital / H.Schroeder).

Particle detectors like the ones used by physicists at CERN can have wide applications beyond fundamental research. Scientists from the German National Center for Tumor Diseases (NCT), the German Cancer Research Center (DKFZ), and the Heidelberg Ion Beam Therapy Center (HIT) at Heidelberg University Hospital are now testing a new imaging device supplied by the Czech company ADVACAM on its first patients. The device, which includes a small Timepix3 pixel detector developed at CERN, allows head and neck tumours to be closely monitored during ion radiotherapy, making them easier to target and thus helping limit the treatment’s side effects.

"One of the most advanced methods for treating head and neck tumours involves irradiation with ion beams. This has one unique feature: it can be precisely tailored to the depth inside the human head where the particles should have the maximal effect”, explains Mária Martišíková, the head of the DKFZ team.

Yet like other types of irradiation, ion radiation also has a drawback. The particle beams affect not only the tumour but also part of the healthy tissue around it. This is particularly challenging in the brain, where damage to the optic nerve or a patient’s memory are possible. Ideally, the irradiated area around the tumour should be as small as possible, and the dose to the tumour should be as high as possible. However, current technology does not allow for sufficiently precise targeting of the ions.

To complicate matters further, the situation inside a patient's head can change during therapy. The x-ray computed tomography (CT) scan image taken before treatment is essentially used as a "map" to target the tumour with ion beams. But during therapy, the situation inside the skull may evolve. Until now, physicians lacked a reliable tool to alert them in case of a change in the brain.

The new ADVACAM device could help solve these issues, by improving the navigation of the ion beams inside the head by tracking the secondary particles that are created when ions pass through it.

"Our cameras can register every charged particle of secondary radiation emitted from the patient's body. It's like watching balls scattered by a billiard shot. If the balls bounce as expected according to the CT image, we can be sure we are targeting correctly. Otherwise, it's clear that the 'map' no longer applies. Then it is necessary to replan the treatment," describes Lukáš Marek from ADVACAM.

"We hope the new device will show us how often and where the tumour changes occur. It will allow us to reduce the overall irradiated volume of tissue, saving healthy tissue and reducing the side effects of radiotherapy. We will also be able to apply higher doses of radiation to the tumour" adds Martišíková.

The treatment can benefit enormously from the additional information obtained from the camera. In the first phase, data could lead to an interruption and replanning of the irradiation series when necessary. The ultimate goal is a system that can correct the path of the ion beam in real-time.

The Timepix3 chip developed at CERN is used in the new ADVACAM imaging device. (Image: CERN)

This device exemplifies successful knowledge transfer, showcasing how technology initially developed for detectors used in fundamental physics research can be applied in healthcare.

“When we started developing pixel detectors for the LHC we had one target in mind – to detect and image each particle interaction and thereby help physicists to unravel the secrets of Nature at high energies. The Timepix detectors were developed by the multidisciplinary Medipix Collaborations whose aims are to take the same technology to new fields. Many of those fields were completely unforeseen at the beginning and this application is a brilliant example of that,” says Michael Campbell, Spokesperson of the Medipix Collaborations.

ndinmore Wed, 03/06/2024 - 09:01 Publication Date Wed, 03/06/2024 - 10:03

Small version of a CERN detector could deliver more precise radiotherapy of head tumours

Cern News - Wed, 06/03/2024 - 10:01
Small version of a CERN detector could deliver more precise radiotherapy of head tumours Mária Martišíková (left), the project leader from Heidelberg University Hospital and German Cancer Research Center (DKFZ), and DKFZ researcher Laurent Kelleter. (Image: Heidelberg University Hospital / H.Schroeder).

Particle detectors like the ones used by physicists at CERN can have wide applications beyond fundamental research. Scientists from the German National Center for Tumor Diseases (NCT), the German Cancer Research Center (DKFZ), and the Heidelberg Ion Beam Therapy Center (HIT) at Heidelberg University Hospital are now testing a new imaging device supplied by the Czech company ADVACAM on its first patients. The device, which includes a small Timepix3 pixel detector developed at CERN, allows head and neck tumours to be closely monitored during ion radiotherapy, making them easier to target and thus helping limit the treatment’s side effects.

"One of the most advanced methods for treating head and neck tumours involves irradiation with ion beams. This has one unique feature: it can be precisely tailored to the depth inside the human head where the particles should have the maximal effect”, explains Mária Martišíková, the head of the DKFZ team.

Yet like other types of irradiation, ion radiation also has a drawback. The particle beams affect not only the tumour but also part of the healthy tissue around it. This is particularly challenging in the brain, where damage to the optic nerve or a patient’s memory are possible. Ideally, the irradiated area around the tumour should be as small as possible, and the dose to the tumour should be as high as possible. However, current technology does not allow for sufficiently precise targeting of the ions.

To complicate matters further, the situation inside a patient's head can change during therapy. The x-ray computed tomography (CT) scan image taken before treatment is essentially used as a "map" to target the tumour with ion beams. But during therapy, the situation inside the skull may evolve. Until now, physicians lacked a reliable tool to alert them in case of a change in the brain.

The new ADVACAM device could help solve these issues, by improving the navigation of the ion beams inside the head by tracking the secondary particles that are created when ions pass through it.

"Our cameras can register every charged particle of secondary radiation emitted from the patient's body. It's like watching balls scattered by a billiard shot. If the balls bounce as expected according to the CT image, we can be sure we are targeting correctly. Otherwise, it's clear that the 'map' no longer applies. Then it is necessary to replan the treatment," describes Lukáš Marek from ADVACAM.

"We hope the new device will show us how often and where the tumour changes occur. It will allow us to reduce the overall irradiated volume of tissue, saving healthy tissue and reducing the side effects of radiotherapy. We will also be able to apply higher doses of radiation to the tumour" adds Martišíková.

The treatment can benefit enormously from the additional information obtained from the camera. In the first phase, data could lead to an interruption and replanning of the irradiation series when necessary. The ultimate goal is a system that can correct the path of the ion beam in real-time.

The Timepix3 chip developed at CERN is used in the new ADVACAM imaging device. (Image: CERN)

This device exemplifies successful knowledge transfer, showcasing how technology initially developed for detectors used in fundamental physics research can be applied in healthcare.

“When we started developing pixel detectors for the LHC we had one target in mind – to detect and image each particle interaction and thereby help physicists to unravel the secrets of Nature at high energies. The Timepix detectors were developed by the multidisciplinary Medipix Collaborations whose aims are to take the same technology to new fields. Many of those fields were completely unforeseen at the beginning and this application is a brilliant example of that,” says Michael Campbell, Spokesperson of the Medipix Collaborations.

ndinmore Wed, 03/06/2024 - 09:01 Publication Date Wed, 03/06/2024 - 10:03

Efficient learning of many-body systems

Nature Physics - Wed, 06/03/2024 - 00:00

Nature Physics, Published online: 06 March 2024; doi:10.1038/s41567-024-02393-4

The Hamiltonian describing a quantum many-body system can be learned using measurements in thermal equilibrium. Now, a learning algorithm applicable to many natural systems has been found that requires exponentially fewer measurements than existing methods.

Protecting entanglement between logical qubits via quantum error correction

Nature Physics - Wed, 06/03/2024 - 00:00

Nature Physics, Published online: 06 March 2024; doi:10.1038/s41567-024-02446-8

Despite being essential to many applications in quantum science, entanglement can be easily disrupted by decoherence. A protocol based on repetitive quantum error correction now demonstrates enhanced coherence times of entangled logical qubits.

Learning quantum Hamiltonians from high-temperature Gibbs states and real-time evolutions

Nature Physics - Wed, 06/03/2024 - 00:00

Nature Physics, Published online: 06 March 2024; doi:10.1038/s41567-023-02376-x

Complexity of learning Hamiltonians from Gibbs states is an important issue for both many-body physics and machine learning. The optimal sample and time complexities of quantum Hamiltonian learning for high temperature has now been proven.

The Open Quantum Institute launches its pilot phase at CERN

Cern News - Mon, 04/03/2024 - 16:46
The Open Quantum Institute launches its pilot phase at CERN

The Open Quantum Institute (OQI) passes a new milestone today, with the operational launch at CERN. Following a successful one-year incubation period led by the Geneva Science and Diplomacy Anticipator (GESDA), the new, three-year CERN-based pilot will build on the efforts to date to help unleash the full power of quantum computing for the benefit of all.

Proposed, designed, and incubated through GESDA, in collaboration with some 180 experts from all over the world, the OQI is a multilateral science diplomacy initiative, uniting academia, technology companies, the private sector, the diplomatic community, philanthropy organisations and global citizens in a joint effort towards more open and inclusive quantum computing. By facilitating equal access to cutting-edge nascent technologies, the OQI seeks to accelerate the potential of quantum computing for all society and to support the development of concrete quantum solutions aimed at achieving the United Nations’ Sustainable Development Goals (SDGs).

During its pilot phase, hosted at CERN and supported by the Union de Banques Suisses (UBS), the OQI will be part of CERN’s wider Quantum Technology Initiative (QTI), launched in 2020 and managed by the IT department. Building on QTI’s mission to explore the full potential of quantum technologies and to maximise their societal impact, the OQI will work to push the boundaries of geography and disciplines to ensure that quantum computing is harnessed to tackle some of the key global challenges.

“CERN offers ideal conditions for the development of the OQI, and my hope is that this initiative will not only be a success, but also a model of what scientific diplomacy can do to promote concrete projects of benefit to humanity”, says Fabiola Gianotti, CERN Director-General. “During the pilot phase, the OQI will benefit from CERN's experience in deploying scientific and technological progress to the benefit of society. We look forward to working with GESDA and other partners from academia, industry and government to ensure that quantum computing is accessible to all, including underserved regions of the world."

The focus will lie on the selection of SDG-related use cases to explore applications of quantum computing in fields like health, energy, climate action, clean water, and food security. Some examples of potential projects include: improving the sustainability of global food systems through quantum computing optimisation (addressing SDG 2, zero hunger); finding quantum machine learning solutions to improve medical imaging accuracy and early diagnosis of diseases (addressing SDG 3, good health and well-being); and using quantum computing simulation to reduce carbon dioxide in the atmosphere (addressing SDG 13, climate action).

“The UN’s SDGs represent the international community’s collective view of what the greatest societal challenges are today,” says Enrica Porcari, Head of CERN’s IT department. “This is why we are proud to host the OQI at CERN and to provide a platform for innovation, fostering real-world applications of quantum computing to address the SDGs.”

CERN will host the OQI from 2024 to 2026 and support three or four projects targeting SDG-related use cases. It will also lay the foundation for the next phase of the programme and potentially become a reference point for other initiatives aimed at deploying quantum technologies to address societal challenges. GESDA will remain the science diplomacy advisor and fundraiser, helping to ensure the continuity of the initiative and contributing to its diplomatic engagement, while UBS will act as the lead support partner, ensuring further growth of the institute.

Organisations and individuals, committed to human-centred, inclusive and responsible quantum computing, can play their part in OQI by submitting use cases for SDGs, developing educational tools, curating the diplomatic dialogue on quantum computing and much more.

For full details on how to get involved, please visit the website, and follow OQI on LinkedIn and X.

abelchio Mon, 03/04/2024 - 15:46 Byline Anastasiia Lazuka Publication Date Tue, 03/05/2024 - 17:31

The Open Quantum Institute launches its pilot phase at CERN

Cern News - Mon, 04/03/2024 - 16:46
The Open Quantum Institute launches its pilot phase at CERN

The Open Quantum Institute (OQI) passes a new milestone today, with the operational launch at CERN. Following a successful one-year incubation period led by the Geneva Science and Diplomacy Anticipator (GESDA), the new, three-year CERN-based pilot will build on the efforts to date to help unleash the full power of quantum computing for the benefit of all.

Proposed, designed, and incubated through GESDA, in collaboration with some 180 experts from all over the world, the OQI is a multilateral science diplomacy initiative, uniting academia, technology companies, the private sector, the diplomatic community, philanthropy organisations and global citizens in a joint effort towards more open and inclusive quantum computing. By facilitating equal access to cutting-edge nascent technologies, the OQI seeks to accelerate the potential of quantum computing for all society and to support the development of concrete quantum solutions aimed at achieving the United Nations’ Sustainable Development Goals (SDGs).

During its pilot phase, hosted at CERN and supported by the Union de Banques Suisses (UBS), the OQI will be part of CERN’s wider Quantum Technology Initiative (QTI), launched in 2020 and managed by the IT department. Building on QTI’s mission to explore the full potential of quantum technologies and to maximise their societal impact, the OQI will work to push the boundaries of geography and disciplines to ensure that quantum computing is harnessed to tackle some of the key global challenges.

“CERN offers ideal conditions for the development of the OQI, and my hope is that this initiative will not only be a success, but also a model of what scientific diplomacy can do to promote concrete projects of benefit to humanity”, says Fabiola Gianotti, CERN Director-General. “During the pilot phase, the OQI will benefit from CERN's experience in deploying scientific and technological progress to the benefit of society. We look forward to working with GESDA and other partners from academia, industry and government to ensure that quantum computing is accessible to all, including underserved regions of the world."

The focus will lie on the selection of SDG-related use cases to explore applications of quantum computing in fields like health, energy, climate action, clean water, and food security. Some examples of potential projects include: improving the sustainability of global food systems through quantum computing optimisation (addressing SDG 2, zero hunger); finding quantum machine learning solutions to improve medical imaging accuracy and early diagnosis of diseases (addressing SDG 3, good health and well-being); and using quantum computing simulation to reduce carbon dioxide in the atmosphere (addressing SDG 13, climate action).

“The UN’s SDGs represent the international community’s collective view of what the greatest societal challenges are today,” says Enrica Porcari, Head of CERN’s IT department. “This is why we are proud to host the OQI at CERN and to provide a platform for innovation, fostering real-world applications of quantum computing to address the SDGs.”

CERN will host the OQI from 2024 to 2026 and support three or four projects targeting SDG-related use cases. It will also lay the foundation for the next phase of the programme and potentially become a reference point for other initiatives aimed at deploying quantum technologies to address societal challenges. GESDA will remain the science diplomacy advisor and fundraiser, helping to ensure the continuity of the initiative and contributing to its diplomatic engagement, while UBS will act as the lead support partner, ensuring further growth of the institute.

Organisations and individuals, committed to human-centred, inclusive and responsible quantum computing, can play their part in OQI by submitting use cases for SDGs, developing educational tools, curating the diplomatic dialogue on quantum computing and much more.

For full details on how to get involved, please visit the website, and follow OQI on LinkedIn and X.

abelchio Mon, 03/04/2024 - 15:46 Byline Anastasiia Lazuka Publication Date Tue, 03/05/2024 - 17:31

LHCb observes a new decay mode of the charmed beauty meson

Cern News - Mon, 04/03/2024 - 11:15
LHCb observes a new decay mode of the charmed beauty meson

The LHCb collaboration recently reported the first observation of the decay of the Bc+ meson (composed of two heavy quarks, b and c) into a J/ψ charm-anticharm quark bound state and a pair of pions, π+π0. The decay process shows a contribution from an intermediate particle, a ρ+ meson that forms for a brief moment and then decays into the π+π0 pair.

The Bc+ is the heaviest meson that can only decay through the weak interactions, via the decay of one heavy constituent quark. Bc+ decays into an odd number of light hadrons and a J/ψ (or other charm-anticharm quark bound states, called “charmonia”) have been studied intensively and have been found to be in remarkable agreement with the theoretical expectations. The decay of Bc+ into a J/ψ and a π+π0 pair is the simplest decay into charmonium and an even number of light hadrons. It has never been observed before, mainly because the precise reconstruction of the low-energy π0 meson through its decay into a pair of photons is very challenging in an LHC proton-proton collision environment.

A precise measurement of the Bc+→J/ψπ+π0 decay will allow better understanding of its possible contribution as a background source for the study of other decays of Bc mesons as well as rare decays of B0 mesons. From the theoretical point of view, decays of Bc into J/ψ and an even number of pions are closely related to the decays of the τ lepton into an even number of pions, and to the e+e– annihilation into an even number of pions. Precise measurements of e+e– annihilation into two pions in the ρ mass region (as in the Bc decay discussed here) are crucial for the interpretation of results from the Fermilab g-2 experiment measuring the anomalous magnetic dipole moment of the muon, since low-energy e+e– annihilation into hadrons is an important source of the uncertainty of the g-2 measurements.

The ratio of the probability of the new decay to that of the decay of Bc+ into J/ψπ+ has been calculated by various theorists over the last 30 years. Now these predictions can finally be compared with an experimental measurement: most predictions agree with the new result obtained by LHCb (2.80±0.15±0.11±0.16).

The large number of b-quarks produced in LHC collisions and the excellent detector allows LHCb to study the production, decays and other properties of the Bc+ meson in detail. Since the meson’s discovery by the CDF experiment at the Tevatron collider, 18 new Bc+ decays have been observed (with more than five standard deviations), all of them by LHCb.

Read more in the LHCb paper.

ptraczyk Mon, 03/04/2024 - 10:15 Byline LHCb collaboration Publication Date Mon, 03/04/2024 - 10:06

LHCb observes a new decay mode of the charmed beauty meson

Cern News - Mon, 04/03/2024 - 11:15
LHCb observes a new decay mode of the charmed beauty meson The LHCb detector (Image: M. Brice/CERN)

The LHCb collaboration recently reported the first observation of the decay of the Bc+ meson (composed of two heavy quarks, b and c) into a J/ψ charm-anticharm quark bound state and a pair of pions, π+π0. The decay process shows a contribution from an intermediate particle, a ρ+ meson that forms for a brief moment and then decays into the π+π0 pair.

The Bc+ is the heaviest meson that can only decay through the weak interactions, via the decay of one heavy constituent quark. Bc+ decays into an odd number of light hadrons and a J/ψ (or other charm-anticharm quark bound states, called “charmonia”) have been studied intensively and have been found to be in remarkable agreement with the theoretical expectations. The decay of Bc+ into a J/ψ and a π+π0 pair is the simplest decay into charmonium and an even number of light hadrons. It has never been observed before, mainly because the precise reconstruction of the low-energy π0 meson through its decay into a pair of photons is very challenging in an LHC proton-proton collision environment.

A precise measurement of the Bc+→J/ψπ+π0 decay will allow better understanding of its possible contribution as a background source for the study of other decays of Bc mesons as well as rare decays of B0 mesons. From the theoretical point of view, decays of Bc into J/ψ and an even number of pions are closely related to the decays of the τ lepton into an even number of pions, and to the e+e– annihilation into an even number of pions. Precise measurements of e+e– annihilation into two pions in the ρ mass region (as in the Bc decay discussed here) are crucial for the interpretation of results from the Fermilab g-2 experiment measuring the anomalous magnetic dipole moment of the muon, since low-energy e+e– annihilation into hadrons is an important source of the uncertainty of the g-2 measurements.

The ratio of the probability of the new decay to that of the decay of Bc+ into J/ψπ+ has been calculated by various theorists over the last 30 years. Now these predictions can finally be compared with an experimental measurement: most predictions agree with the new result obtained by LHCb (2.80±0.15±0.11±0.16).

The large number of b-quarks produced in LHC collisions and the excellent detector allows LHCb to study the production, decays and other properties of the Bc+ meson in detail. Since the meson’s discovery by the CDF experiment at the Tevatron collider, 18 new Bc+ decays have been observed (with more than five standard deviations), all of them by LHCb.

Read more in the LHCb paper.

ptraczyk Mon, 03/04/2024 - 10:15 Byline LHCb collaboration Publication Date Mon, 03/04/2024 - 10:06

Drug design on quantum computers

Nature Physics - Mon, 04/03/2024 - 00:00

Nature Physics, Published online: 04 March 2024; doi:10.1038/s41567-024-02411-5

Quantum computers promise to efficiently predict the structure and behaviour of molecules. This Perspective explores how this could overcome existing challenges in computational drug discovery.

Graph states of atomic ensembles engineered by photon-mediated entanglement

Nature Physics - Fri, 01/03/2024 - 00:00

Nature Physics, Published online: 01 March 2024; doi:10.1038/s41567-024-02407-1

Photon-mediated entanglement in atomic ensembles coupled to cavities enables the engineering of quantum states with a graph-like entanglement structure. This offers potential advantages in quantum computation and metrology.

Cavity-mediated long-range interactions in levitated optomechanics

Nature Physics - Fri, 01/03/2024 - 00:00

Nature Physics, Published online: 01 March 2024; doi:10.1038/s41567-024-02405-3

Combining multiparticle levitation with cavity control enables cavity-mediated interaction between levitated nanoparticles, whose strength can be tailored via optical detuning and position of the two particles.

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phone: +30 2810 394300 - email: chair@physics.uoc.gr