Tag Archives: decay

Gel That Restores Tooth Enamel Could Help Prevent Decay

Posted on by
Reply

Enamel shields teeth from harm, yet can be easily compromised

Agrobacter/Getty Images

The gel incorporates compounds found in saliva to aid in the repair and regeneration of tooth enamel while preventing cavity formation that necessitates fillings.

Enamel, the tough and glossy outer layer of teeth, safeguards the sensitive inner part from wear, acids, and bacteria. “Enamel serves as your initial defense; when it starts to deteriorate, tooth decay accelerates,” explains Dr. Alvaro Mata from the University of Nottingham, UK. Since enamel does not self-repair, methods like fluoride varnishes and remineralizing treatments merely prevent further deterioration.

In search of a solution, Mata and his team engineered a gel that contains a modified protein designed to mimic amelogenin, which is vital for enamel growth in early development.

Tests revealed that applying the gel to human teeth under a microscope in a calcium and phosphate solution—the essential components of enamel—yielded a thin, robust layer that persisted for weeks, even during brushing.

This gel establishes a framework that utilizes calcium and phosphate to fill imperfections and encourage the organized development of new crystals in the enamel beneath the gel layer, even if a significant portion of the dentin is exposed.

“The gel successfully grew crystals epitaxially, meaning it mirrored the crystal orientation of the existing enamel,” Mata states.

This alignment allows the new growth, achieving thicknesses of up to 10 micrometers, to integrate with the underlying natural tissue, reconstructing both the structure and functionality of the enamel. “Growth occurs within a week,” remarks Mata. The method proved effective not only with the specific solution employed but also with donated saliva, which naturally contains calcium and phosphate.

Electron microscopy images of a demineralized tooth showcasing eroded crystals (left) and a similar tooth after two weeks of gel treatment that reveals epitaxially regenerated enamel crystals (right)

Professor Alvaro Mata, University of Nottingham

A comparable approach was noted in 2019, but it resulted in a thinner coating, only partially restoring the inner enamel structure.

Clinical trials on humans are set to commence early next year. Mata is also establishing a company named Mintech-Bio, hoping to launch its first product by late 2026 for use by dentists.

Source: www.newscientist.com

Physicists discover proof of asymmetry between matter and antimatter in decay of baryons and beauty hadrons

Posted on by
Reply

The standard model of particle physics predicts an asymmetry between matter and antimatter known as charge parity (CP) violation. However, the size of this asymmetry in the Standard Model is not large enough to explain the disequilibrium, and so far the asymmetry has only been observed in certain decays of particles called mesons. In two new studies, LHCb collaboration CERN’s Large Hadron Collider (LHC) has discovered evidence of CP violation in baryon decay and beauty hadron decay into charmonium particles, shedding light on these two pieces of the matter-antimatter puzzle.

Exterior view of the LHCb detector. Image credit: CERN.

Experiments involving LHCb have previously searched for baryon CP violation by looking for differences in the way matter and antimatter baryons decay into other particles.

However, these investigations have so far been essentially empty-handed.

One LHCb study provided evidence for a process in the specific collapse of the bottom lambda baryon, but subsequent studies analyzing larger samples of such collapses did not increase that evidence.

in first new studyLHCb physicists scrutinized proton-proton collision data obtained during the first and second runs of the LHC and discovered various decay modes of the bottom lambda baryon, including decay into a lambda baryon and two kaons. You have searched for

We then investigated the CP violation in each decay mode, essentially by counting the number of decays of the bottom lambdabaryon and its antimatter partner and taking the difference between the two.

In the case of the lambda baryon and its decay into two kaons, this difference showed evidence of a CP violation with a significance of 3.2 standard deviations.

in second studythe LHCb team focused on the decay of a beautiful charged meson into J/psi and a charged pion.

J/psi is a charmmonium particle, a meson consisting of a charm quark and a charm antiquark.

We performed an analysis similar to the lower lambda baryon study, also using data from the first and second runs of the LHC, and found evidence for CP violation in this decay mode of charged meons. Again, the significance is 3.2 standard. Deviation.

This finding represents evidence of CP violation in the decay of beauty hadrons to charmonium particles.

“Our study represents an important step toward establishing whether CP violations are present in these types of collapses,” the authors state.

“Data from the high-luminosity LHC, with its third experiment and planned collider upgrades, will shed further light on these and other parts of the matter-antimatter puzzle. .”

_____

LHCb collaboration. 2024. Study of Λ0b and Ξ0b decay to Λh+h'- and evidence of CP violation in Λ0b→ΛK+K- decay. arXiv: 2411.15441

LHCb collaboration. 2024. First evidence of direct CP violation to charmonium decay in cosmetology. arXiv: 2411.12178

Source: www.sci.news

CERN physicists witness exceptionally rare hyperon decay

Posted on by
Reply

A hyperon is a particle that contains three quarks, like a proton or a neutron, and one or more strange quarks. Physicists from the LHCb collaboration at the Large Hadron Collider (LHC) at CERN say they have observed a hyperon decay Σ+→pμ+μ- in proton-proton collisions.

A view of the LHCb detector. Image courtesy of CERN.

“Rare decays of known particles are a promising tool for exploring physics beyond the Standard Model of particle physics,” said the LHCb physicist.

“In the Standard Model, the Σ+ → pμ+μ- process is only possible through a loop diagram, meaning that the decay does not occur directly, but intermediate states have to be exchanged within the loop.”

“In quantum field theory, the probability of such a process occurring is the sum of the probabilities of all particles, both known and unknown, that can possibly be exchanged in this loop.”

“This is what makes such processes sensitive to new phenomena.”

“If a discrepancy is observed between experimental measurements and theoretical calculations, it may be caused by the contribution of some unknown particle.”

“These particles can either be exchanged within the loop or directly mediate this decay, interacting with the quarks and decaying into pairs of muons.”

“In the latter case, the new particle would leave a signature on the properties of the two muons.”

The study of the Σ+ → pμ+μ- decay has been particularly exciting thanks to hints of structure observed in the properties of muon pairs by the HyperCP collaboration in 2005.

With only three occurrences the structure was far from conclusive, and it was hoped that new research would shed light on the situation.

Finally, the LHCb data did not show any significant peak structure in the two-muon mass region highlighted by HyperCP, thus refuting the hint.

However, the new study observes the decay with a high degree of significance, followed by precise measurements of the decay probability and other parameters, which will allow further investigation of the discrepancy with the Standard Model predictions.

“In data collected in Run 2 of pp collisions at the LHCb experiment, the Σ+ → pμ+μ− decay is observed with very high significance, with a yield of NΣ+→pμ+μ− = 279 ± 19,” the authors write in their paper. paper.

“We do not see any structure in the two-muon invariant mass distribution that is consistent with the Standard Model predictions.”

“The collected signal yield allows for measurements of integral and differential branching rates, as well as other measurements such as charge-parity symmetry breaking and front-to-back asymmetry.”

_____

LHCb Collaboration. 2024. Observation of rare Σ+→pμ+μ− decays at LHCb. CERN-LHCb-CONF-2024-002

Source: www.sci.news

Scientists witness uncommon nuclear decay of potassium isotope

Posted on by
Reply

Physicists are Potassium Decay (KDK) Collaboration. They directly observed for the first time a very rare but important decay pathway from potassium-40 to argon-40. Their results have the potential to improve current understanding of physical processes and increase the accuracy of geological dating.

Decay scheme of potassium 40. Image credit: Stukel other., doi: 10.1103/PhysRevLett.131.052503.

Potassium-40 is a ubiquitous natural isotope whose radioactivity has been used to estimate geological ages over billions of years, to theories of nuclear structure, and to the search for subatomic rare events such as dark matter and neutrinoless double beta decay. influence.

The decay of this long-lived isotope must be precisely known for its use as a global clock and to explain its presence in low-background experiments.

Although potassium-40 has several known decay modes, the electron-capture decay predicted directly into the ground state of argon-40 has never been observed before.

“Some of the nuclei of certain elements radioactively decay into the nuclei of other elements. These decays can be helpful or annoying, depending on the situation,” the KDK physicists said. I am.

“This is especially true for potassium-40, an isotope that normally decays to calcium-40, but about 10% of the time it decays to argon-40.”

“This decay pathway involves a process called electron capture, which provides information about the nuclear structure.”

“Potassium-40 has a very long half-life, so it can even determine the age of geological objects on billion-year time scales.”

“Due to its long half-life, it is difficult to find another way for potassium-40 to break down.”

In a new study, researchers measured a rare decay branch of potassium-40 at Oak Ridge National Laboratory's Holyfield Radioactive Ion Beam Facility.

“Quantifying the decay rate of potassium-40 and its decay branches is difficult because it requires measuring the parent nucleus and a sufficient number of rare progeny nuclei,” the researchers said.

“We studied a subset of potassium-40 that decays to argon-40 by electron capture, which accounts for about 10% of all potassium-40 decays.”

“Although most potassium-40 electron-capture decays emit characteristic gamma rays that form the background of most experiments, a small subset of these decays occur without gamma ray emission.”

“This happens when potassium-40 captures an electron that goes directly to the ground state of argon-40.”

“We have directly measured this decay for the first time. This result indicates that other decay rates may also need to be reevaluated.”

“The rare decay branch we identified and measured provides unique experimental evidence for so-called forbidden beta decay, with implications for predictions of nuclear structure and for potassium-based geological and solar system age estimates. It removes years of uncertainty.”

“This discovery also improves our assessment of the background that exists in experiments that explore new physics beyond the Standard Model.”

The results are published in two papers (paper #1 and paper #2) in the diary physical review letter and diary Physical Review C.

_____

M. Stukel other. (KDK collaboration). 2024. 40,000 rare collapses with implications for fundamental physics and geochronology. Physics.pastor rhett 131 (5): 052503; doi: 10.1103/PhysRevLett.131.052503

L. Harias other. (KDK collaboration). 2024. Evidence of ground state electron capture at 40K. Physics. Rev.C 108 (1): 014327; doi: 10.1103/PhysRevC.108.014327

Source: www.sci.news

Nuclear Physicist Investigates Tantalum Decay in 180m Isotope

Posted on by
Reply

Tantalum-180m (180mTa) is a rare isotope of tantalum whose decay has never been observed, and whose lifetime is expected to be about a million times longer than the age of the universe.

Modified Majorana module in assembly glovebox with germanium detector crystal and tantalum sample installed. Image credit: Majorana Collaboration.

Tantalum, a chemical element with symbol Ta and atomic number 73, is a rare, hard, blue-gray, shiny transition metal with excellent corrosion resistance.

It has multiple stable isotopes: 2 stable radioisotopes and 35 artificial radioisotopes.

Tantalum-180, the least abundant isotope, occurs naturally in a long-lived excited state.

In an excited state, the protons or neutrons in the nucleus have a higher energy level than normal.

Although energetically possible, radioactive decay of this excited state in tantalum-180m has never been observed before.

Nuclear physicists from the Majorana collaboration are currently conducting experiments aimed at measuring this decay, which is expected to have a lifetime about a million times longer than the age of the universe.

For the experiment, they Majorana Demonstrator At Sanford Underground Research Facility.

Additionally, a significantly larger amount of tantalum samples were introduced compared to tantalum samples previously used in similar studies.

Over the course of a year, they collected data using a series of high-purity germanium detectors with exceptional energy resolution.

They also developed analytical methods specifically tailored to detect multiple expected decay signatures.

As a result of these combined efforts, we were able to establish unprecedented limits that fall within the range of 10.18 up to 1019 Year.

This level of sensitivity represents the first example in which half-life values ​​predicted from nuclear theory have become achievable.

Although the collapse process has not yet been observed, these advances have significantly enhanced existing limits by one to two orders of magnitude.

Additionally, this advance allowed the Majorana team to ignore certain parameter ranges associated with various potential dark matter particles.

“With a new limit of up to 1.5*1019 “This is the most sensitive search for a single β and electron capture decay achieved to date,” the authors said.

“Across all channels, you can exclude attenuation with T1/2<0.29*10.”18For years. ”

of result appear in the diary physical review letter.

_____

IJ Arnquist other. (Majorana collaboration).Constraints on collapse 180mTa. Physics.pastor rhett 131 (15): 152501; doi: 10.1103/PhysRevLett.131.152501

Source: www.sci.news

Physicists at CERN Discover Intriguing New Decay Mode of Mesons

Posted on by
Reply

Physicists from LHCb collaboration at CERN’s Large Hadron Collider (LHC) have made the first observation of the collapse of the Bc+ meson. This results in a J/ψ charm-anticharm quark bound state (consisting of two heavy quarks, b and c) and a pair of pions π+π0. This new decay process shows a contribution from an intermediate particle, the ρ+ meson, which forms for a short time and then decays into π+π0 pairs.

September 2016, LHCb experimental cave at LHC IP8. Image courtesy of CERN.

The Bc+ is the heaviest meson and decays only through weak interactions due to the decay of one heavy constituent quark.

It decays into an odd number of optical hadrons, and J/ψ (or another attractive and anti-attractive quark-bound state called Charmonia) has been intensively studied and found to be in remarkable agreement with theoretical predictions.

The decay of Bc+ to J/ψ and π+π0 pairs is the simplest decay to charmonium and even-numbered optical hadrons.

This has never been observed before. The main reason for this is that in the LHC proton-proton collision environment, it is very difficult to accurately reconstruct low-energy π0 mesons through their decay into a pair of photons.

“Accurate measurements of the Bc+→J/ψπ+π0 decay will allow us to better understand its possible contribution as a background source for the study of other decays of Bc mesons and rare decays of B0 mesons,” said the LHCb physicist.

From a theoretical point of view, J/ψ and the decay of Bc into an even number of pions are closely related to the decay of the τ lepton into an even number of pions and the e+e- annihilation into an even number of pions.

Accurate measurements of e+e- annihilation into two pions in the ρ mass region (like the Bc decay discussed here) are possible using the Fermilab G-2 experiment, which measures the anomalous magnetic dipole moment of the muon and is important for interpreting the results. The annihilation of low-energy e+e- into hadrons is an important source of uncertainty in g-2 measurements.

The ratio of the probability of a new decay to the probability of a decay from Bc+ to J/ψπ+ has been calculated by various theorists over the past 30 years.

Now these predictions can finally be compared with experimental measurements. Most predictions agree with the new result 2.80±0.15±0.11±0.16.

The large number of b quarks produced in LHC collisions and the excellent detectors allow LHCb researchers to study the formation, decay, and other properties of Bc+ mesons in detail.

“Since the discovery of the meson by the Tevatron Collider’s CDF experiment, 18 new Bc+ decays (with more than 5 standard deviations) have been observed, all from the LHCb,” the researchers said.

_____

LHCb collaboration. 2024. Observation of B+c→J/ψπ+π0 collapse. arXiv: 2402.05523

Source: www.sci.news