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45-448: PANDA will use proton–antiproton annihilation to study strong interaction physics at medium energy including hadron spectroscopy, search for exotic hadrons, hadrons in media, nucleon structure and exotic nuclei. A more detailed description of the experiment is available at the scholarpedia . A proton beam will be provided by the existing GSI facility and will be further accelerated by FAIR's SIS100 ring accelerator up to 30 GeV. By

90-431: A photon ( γ ), gluon ( g ), Z , or a Higgs boson ( H ). If the total energy in the center-of-momentum frame is equal to the rest mass of a real boson (which is impossible for a massless boson such as the γ ), then that created particle will continue to exist until it decays according to its lifetime . Otherwise,

135-434: A W boson . If the annihilating particles are composite , such as mesons or baryons , then several different particles are typically produced in the final state. The inverse of annihilation is pair production , the process in which a high-energy photon converts its energy into mass. If the initial two particles are elementary (not composite), then they may combine to produce only a single elementary boson , such as

180-662: A Target Spectrometer surrounding the target area and a Forward Spectrometer to detect particles going into the very forward direction. This guarantees an almost 4π acceptance and a good momentum resolution. The PANDA experiment will use the Outer Tracker from the LHCb experiment at the Large Hadron Collider (LHC) at CERN. This physics -related article is a stub . You can help Misplaced Pages by expanding it . Annihilation Onia In particle physics , annihilation

225-446: A collision energy of 7 TeV. In 2012, about 2 fb was collected at an energy of 8 TeV. During 2015–2018 (Run 2 of the LHC), about 6 fb was collected at a center-of-mass energy of 13 TeV. In addition, small samples were collected in proton-lead, lead-lead, and xenon-xenon collisions. The LHCb design also allowed the study of collisions of particle beams with a gas (helium or neon) injected inside

270-558: A given decay to happen, was found to be 0.846 − 0.041 + 0.044 {\displaystyle 0.846_{-0.041}^{+0.044}} while the Standard Model predicts it to be very close to unity. In December 2022 improved measurements discarded this anomaly. In August 2023 joined searches in leptonic decays b → s ℓ + ℓ − {\displaystyle b\rightarrow s\ell ^{+}\ell ^{-}} by

315-533: A period of about three years. The detector operates in vacuum and is cooled to approximately −25 °C (−13 °F) using a biphase CO 2 system. The data of the VELO detector are amplified and read out by the Beetle ASIC . The RICH-1 detector ( Ring imaging Cherenkov detector ) is located directly after the vertex detector. It is used for particle identification of low- momentum tracks. The main tracking system

360-431: A sea quark) to produce a gluon, after which the gluon together with the remaining quarks, antiquarks, and gluons will undergo a complex process of rearrangement (called hadronization or fragmentation ) into a number of mesons , (mostly pions and kaons ), which will share the total energy and momentum. The newly created mesons are unstable, and unless they encounter and interact with some other material, they will decay in

405-699: A series of reactions that ultimately produce only photons , electrons , positrons , and neutrinos . This type of reaction will occur between any baryon (particle consisting of three quarks) and any antibaryon consisting of three antiquarks, one of which corresponds to a quark in the baryon. (This reaction is unlikely if at least one among the baryon and anti-baryon is exotic enough that they share no constituent quark flavors.) Antiprotons can and do annihilate with neutrons , and likewise antineutrons can annihilate with protons, as discussed below. Reactions in which proton–antiproton annihilation produces as many as 9 mesons have been observed, while production of 13 mesons

450-443: A wide variety of exotic heavy particles are created. The word "annihilation" takes its use informally for the interaction of two particles that are not mutual antiparticles – not charge conjugate . Some quantum numbers may then not sum to zero in the initial state, but conserve with the same totals in the final state. An example is the "annihilation" of a high-energy electron antineutrino with an electron to produce

495-581: Is a particle physics detector experiment collecting data at the Large Hadron Collider at CERN . LHCb is a specialized b-physics experiment, designed primarily to measure the parameters of CP violation in the interactions of b- hadrons (heavy particles containing a bottom quark ). Such studies can help to explain the matter-antimatter asymmetry of the Universe. The detector is also able to perform measurements of production cross sections, exotic hadron spectroscopy, charm physics and electroweak physics in

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540-597: Is determined by a large dipole magnet with the main field component in the vertical direction. [REDACTED] The Vertex Locator (VELO) is built around the proton interaction region. It is used to measure the particle trajectories close to the interaction point in order to precisely separate primary and secondary vertices. The detector operates at 7 millimetres (0.28 in) from the LHC beam. This implies an enormous flux of particles; VELO has been designed to withstand integrated fluences of more than 10  p/cm per year for

585-404: Is forbidden by momentum conservation—a single photon would carry nonzero momentum in any frame , including the center-of-momentum frame where the total momentum vanishes. Both the annihilating electron and positron particles have a rest energy of about 0.511 million electron-volts (MeV). If their kinetic energies are relatively negligible, this total rest energy appears as the photon energy of

630-447: Is from fusion of two gluons (via annihilation of a heavy quark pair), while two quarks or antiquarks produce more easily identified events through radiation of a Higgs by a produced virtual vector boson or annihilation of two such vector bosons. LHCb experiment 46°14′28″N 06°05′49″E  /  46.24111°N 6.09694°E  / 46.24111; 6.09694 The LHCb ( Large Hadron Collider beauty ) experiment

675-497: Is placed before and after the dipole magnet. It is used to reconstruct the trajectories of charged particles and to measure their momenta. The tracker consists of three subdetectors: Following the tracking system is RICH-2. It allows the identification of the particle type of high-momentum tracks. The electromagnetic and hadronic calorimeters provide measurements of the energy of electrons , photons , and hadrons . These measurements are used at trigger level to identify

720-482: Is the first time CP violation is seen in decays of particles other than kaons or B mesons. The rate of the observed CP asymmetry is at the upper edge of existing theoretical predictions, which triggered some interest among particle theorists regarding possible impact of physics beyond the Standard Model. In 2020, LHCb announced discovery of time-dependent CP violation in decays of B s mesons. The oscillation frequency of B s mesons to its antiparticle and vice versa

765-579: Is the primary design goal of the LHCb experiment. As of 2021, LHCb measurements confirm with a remarkable precision the picture described by the CKM unitarity triangle . The angle γ ( α 3 ) {\displaystyle \gamma \,\,(\alpha _{3})} of the unitarity triangle is now known to about 4°, and is in agreement with indirect determinations. In 2019, LHCb announced discovery of CP violation in decays of charm mesons. This

810-435: Is the process that occurs when a subatomic particle collides with its respective antiparticle to produce other particles, such as an electron colliding with a positron to produce two photons . The total energy and momentum of the initial pair are conserved in the process and distributed among a set of other particles in the final state. Antiparticles have exactly opposite additive quantum numbers from particles, so

855-424: Is theoretically possible. The generated mesons leave the site of the annihilation at moderate fractions of the speed of light and decay with whatever lifetime is appropriate for their type of meson. Similar reactions will occur when an antinucleon annihilates within a more complex atomic nucleus , save that the resulting mesons, being strongly interacting , have a significant probability of being absorbed by one of

900-514: The "doubly charmed" baryon Ξ c c + + {\displaystyle \Xi _{\rm {cc}}^{++}} in 2017, being a first known baryon with two heavy quarks; and of the fully-charmed tetraquark T c c c c {\displaystyle \mathrm {T} _{\rm {cccc}}} in 2020, made of two charm quarks and two charm antiquarks. Studies of charge-parity (CP) violation in B-meson decays

945-539: The HESR. In the high-resolution mode a momentum resolution of Δ p p = 5 ⋅ 10 − 5 {\displaystyle {\frac {\Delta p}{p}}=5\cdot 10^{-5}} and a luminosity of L = 1.6 ⋅ 10 31 c m − 2 s − 1 {\displaystyle {\mathcal {L}}=1.6\cdot 10^{31}\mathrm {cm} ^{-2}s^{-1}} can be achieved. In

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990-410: The VELO volume, making it similar to a fixed-target experiment; this setup is usually referred to as "SMOG". These datasets allow the collaboration to carry out the physics programme of precision Standard Model tests with many additional measurements. As of 2021, LHCb has published more than 500 scientific papers. LHCb is designed to study beauty and charm hadrons . In addition to precision studies of

1035-471: The annihilation (or decay) of an electron–positron pair into a single photon can occur in the presence of a third charged particle, to which the excess momentum can be transferred by a virtual photon from the electron or positron. The inverse process, pair production by a single real photon, is also possible in the electromagnetic field of a third particle. When a proton encounters its antiparticle (and more generally, if any species of baryon encounters

1080-717: The beam hitting the antiproton production target, antiprotons with a momentum of around 3 GeV/c will be produced and can be collected and pre-cooled in the Collector Ring (CR). Afterwards the antiprotons will be injected into the High Energy Storage Ring (HESR). This race track shaped storage ring will host the P̄ANDA experiment. The antiprotons can be cooled using stochastic and later also electron cooling and afterwards slowed down or further accelerated to momenta from p = 1.5 GeV/c up to p = 15 GeV/c. There are two operation modes of

1125-403: The border from Geneva . The (small) MoEDAL experiment shares the same cavern. The experiment has wide physics program covering many important aspects of heavy flavour (both beauty and charm), electroweak and quantum chromodynamics (QCD) physics. Six key measurements have been identified involving B mesons. These are described in a roadmap document that formed the core physics programme for

1170-421: The corresponding antibaryon ), the reaction is not as simple as electron–positron annihilation. Unlike an electron, a proton is a composite particle consisting of three " valence quarks " and an indeterminate number of " sea quarks " bound by gluons . Thus, when a proton encounters an antiproton, one of its quarks, usually a constituent valence quark, may annihilate with an antiquark (which more rarely could be

1215-949: The decays in question are very rare, a larger dataset needs to be analysed in order to make definitive conclusions. In March 2021, LHCb announced that the anomaly in lepton universality crossed the "3 sigma " statistical significance threshold, which translates to a p-value of 0.1%. The measured value of R K = B ( B + → K + μ + μ − ) B ( B + → K + e + e − ) {\displaystyle R_{\rm {K}}={\frac {{\mathcal {B}}(\mathrm {B} ^{+}\to \mathrm {K} ^{+}\mu ^{+}\mu ^{-})}{{\mathcal {B}}(\mathrm {B} ^{+}\to \mathrm {K} ^{+}\mathrm {e} ^{+}\mathrm {e} ^{-})}}} , where symbol B {\displaystyle {\mathcal {B}}} denotes probability of

1260-432: The first high energy LHC running in 2010–2012. They include: The fact that the two b-hadrons are predominantly produced in the same forward cone is exploited in the layout of the LHCb detector. The LHCb detector is a single arm forward spectrometer with a polar angular coverage from 10 to 300 milliradians (mrad) in the horizontal and 250 mrad in the vertical plane. The asymmetry between the horizontal and vertical plane

1305-430: The forward region. The LHCb collaborators, who built, operate and analyse data from the experiment, are composed of approximately 1650 people from 98 scientific institutes, representing 22 countries. Vincenzo Vagnoni succeeded on July 1, 2023 as spokesperson for the collaboration from Chris Parkes (spokesperson 2020–2023). The experiment is located at point 8 on the LHC tunnel close to Ferney-Voltaire , France just over

1350-475: The high luminosity mode the momentum resolution will be Δ p p = 10 − 4 {\displaystyle {\frac {\Delta p}{p}}=10^{-4}} and the luminosity L = 1.6 ⋅ 10 32 c m − 2 s − 1 {\displaystyle {\mathcal {L}}=1.6\cdot 10^{32}\mathrm {cm} ^{-2}s^{-1}} . The P̄ANDA detector consists of

1395-468: The known particles such as mysterious X(3872) , a number of new hadrons have been discovered by the experiment. As of 2021, all four LHC experiments have discovered about 60 new hadrons in total, vast majority of which by LHCb. In 2015, analysis of the decay of bottom lambda baryons (Λ b ) in the LHCb experiment revealed the apparent existence of pentaquarks , in what was described as an "accidental" discovery. Other notable discoveries are those of

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1440-402: The latter have sizeable uncertainties. In the Standard Model, couplings of charged leptons (electron, muon and tau lepton) to the gauge bosons are expected to be identical, with the only difference emerging from the lepton masses. This postulate is referred to as "lepton flavour universality". As a consequence, in decays of b hadrons, electrons and muons should be produced at similar rates, and

1485-527: The particles with large transverse momentum (high-Pt particles). The muon system is used to identify and trigger on muons in the events. At the end of 2018, the LHC was shut down for upgrades, with a restart currently planned for early 2022. For the LHCb detector, almost all subdetectors are to be modernised or replaced. It will get a fully new tracking system composed of a modernised vertex locator, upstream tracker (UT) and scintillator fibre tracker (SciFi). The RICH detectors will also be updated, as well as

1530-400: The photon. When a low-energy electron annihilates a low-energy positron (antielectron), the most probable result is the creation of two or more photons , since the only other final-state Standard Model particles that electrons and positrons carry enough mass–energy to produce are neutrinos , which are approximately 10,000 times less likely to produce, and the creation of only one photon

1575-429: The photons produced. Each of the photons then has an energy of about 0.511 MeV. Momentum and energy are both conserved, with 1.022 MeV of photon energy (accounting for the rest energy of the particles) moving in opposite directions (accounting for the total zero momentum of the system). If one or both charged particles carry a larger amount of kinetic energy, various other particles can be produced. Furthermore,

1620-445: The possibility for triggering a significant number of secondary fission reactions in a subcritical mass and may potentially be useful for spacecraft propulsion . In collisions of two nucleons at very high energies, sea quarks and gluons tend to dominate the interaction rate, so neither nucleon need be an anti-particle for annihilation of a quark pair or "fusion" of two gluons to occur. Examples of such processes contribute to

1665-401: The process is understood as the initial creation of a boson that is virtual , which immediately converts into a real particle + antiparticle pair. This is called an s-channel process. An example is the annihilation of an electron with a positron to produce a virtual photon, which converts into a muon and anti-muon. If the energy is large enough, a Z could replace

1710-559: The production of the long-sought Higgs boson . The Higgs is directly produced very weakly by annihilation of light (valence) quarks, but heavy t or b sea or produced quarks are available. In 2012, the CERN laboratory in Geneva announced the discovery of the Higgs in the debris from proton–proton collisions at the Large Hadron Collider (LHC). The strongest Higgs yield

1755-406: The remaining "spectator" nucleons rather than escaping. Since the absorbed energy can be as much as ~2  GeV , it can in principle exceed the binding energy of even the heaviest nuclei. Thus, when an antiproton annihilates inside a heavy nucleus such as uranium or plutonium , partial or complete disruption of the nucleus can occur, releasing large numbers of fast neutrons. Such reactions open

1800-634: The small difference due to the lepton masses is precisely calculable. LHCb has found deviations from this predictions by comparing the rate of the decay B + → K + μ + μ − {\displaystyle \mathrm {B} ^{+}\to \mathrm {K} ^{+}\mu ^{+}\mu ^{-}} to that of B + → K + e + e − {\displaystyle \mathrm {B} ^{+}\to \mathrm {K} ^{+}\mathrm {e} ^{+}\mathrm {e} ^{-}} , and in similar processes. However, as

1845-422: The sums of all quantum numbers of such an original pair are zero. Hence, any set of particles may be produced whose total quantum numbers are also zero as long as conservation of energy , conservation of momentum , and conservation of spin are obeyed. During a low-energy annihilation, photon production is favored, since these particles have no mass. High-energy particle colliders produce annihilations where

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1890-412: The whole detector electronics. However, the most important change is the switch to the fully software trigger of the experiment, which means that every recorded collision will be analysed by sophisticated software programmes without an intermediate hardware filtering step (which was found to be a bottleneck in the past). During the 2011 proton-proton run, LHCb recorded an integrated luminosity of 1 fb at

1935-516: Was found close to the Standard Model predictions. This measurement has harshly limited the possible parameter space of supersymmetry theories, which have predicted a large enhancement in rate. Since then, LHCb has published several papers with more precise measurements in this decay mode. Anomalies were found in several rare decays of B mesons. The most famous example in the so-called P 5 ′ {\displaystyle \mathrm {P} _{5}^{'}} angular observable

1980-428: Was found in the decay B 0 → K ∗ 0 μ + μ − {\displaystyle \mathrm {B} ^{0}\to \mathrm {K} ^{*0}\mu ^{+}\mu ^{-}} , where the deviation between the data and theoretical prediction has persisted for years. The decay rates of several rare decays also differ from the theoretical predictions, though

2025-582: Was measured to a great precision in 2021. Rare decays are the decay modes harshly suppressed in the Standard Model, which makes them sensitive to potential effects from yet unknown physics mechanisms. In 2014, LHCb and CMS experiments published a joint paper in Nature announcing the discovery of the very rare decay B s 0 → μ + μ − {\displaystyle \mathrm {B} _{\rm {s}}^{0}\to \mu ^{+}\mu ^{-}} , rate of which

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