Ukwembula Imfihlakalo ye-Matter-Antimatter Asymmetry ye-Universe nge-Neutrino Oscillation Experiments

I-T2K, isisekelo eside i-neutrino i-oscillation experiment e-Japan, isanda kubika ukuqaphela lapho bethole khona ubufakazi obuqinile bomehluko phakathi kwezakhiwo eziyisisekelo zemvelo neutrinos kanye nozakwabo we-antimatter ohambisanayo, ama-anti-neutrino. Lokhu kuhlola kusikisela ekuchazeni enye yezimfihlakalo ezinkulu zesayensi - incazelo yokubusa ndaba ku Universe phezu kwe-antimatter, kanjalo nokuba khona kwethu.

The ndaba- i-asymmetry ye-antimatter ye Universe

Ngokombono we-Cosmology, izinhlayiya nama-antiparticles azo akhiqizwa ngamabili avela emisebeni ngesikhathi se-Big-Bang. Ama-Antiparticles ama-antimatter anezakhiwo ezibonakalayo ezifanayo nezawo ndaba izinhlayiya, ngaphandle kokushaja kagesi kanye nezakhiwo kazibuthe ezihlehlisiwe. Nokho, i Universe ikhona futhi yakhiwe ngendaba kuphela ekhombisa ukuthi ukulinganisa okuthile kwe-matter antimatter kwaphulwa phakathi nenkathi ye-Big-Bang, ngenxa yalokho amapheya awakwazanga ukuqeda ngokuphelele ukukhiqiza imisebe futhi. Izazi zefiziksi zisafuna amasiginesha okwephulwa kwe-CP-symmetry, okungase kuchaze i-symmetry ephukile ye-antimatter ekuqaleni. Universe.

I-CP-symmetry iwumkhiqizo wama-symmetries amabili ahlukene - ukuhlanganisa i-charge (C) kanye nokuguqulwa kwe-parity (P). I-Charge-conjugation C uma isetshenziswa ezinhlayiyeni ezishajiwe kushintsha uphawu lokushajwa kwayo, ngakho inhlayiya eshajwe kahle iba yi-negative-charged bese kuthi ngokuphambene nalokho. Izinhlayiya ezingathathi hlangothi zihlala zingashintshile ngaphansi kwesenzo se-C. I-Parity-reversal symmetry ihlehlisa izixhumanisi zendawo zezinhlayiya esebenza phezu kwazo - ngakho izinhlayiya ezingakwesokudla ziba kwesokunxele, okufana nalokho okwenzekayo lapho umuntu emi phambi kwesibuko. Ekugcineni, lapho i-CP isebenza engxenyeni yesandla sokudla eshajelwe kabi, iguqulelwa ekubeni enesandla sobunxele, okuyi-antiparticle. Ngakho ndaba futhi i-antimatter ihlobene enye nenye nge-CP-symmetry. Ngakho-ke i-CP kumele iphuliwe ukuze kukhiqizwe lokho okuphawuliwe i-asymmetry ye-antimatter, okwaboniswa okokuqala nguSakharov ngo-1967 (1).

Njengoba amandla adonsela phansi, amandla kazibuthe kanye nokusebenzisana okuqinile kungaguquki ngaphansi kwe-CP-symmetry, okuwukuphela kwendawo yokubheka ukwephulwa kwe-CP Emvelweni kusesimweni sama-quark kanye/noma amalepton, asebenzisana ngokusebenzisana okubuthakathaka. Kuze kube manje, ukwephulwa kwe-CP kukalwe ngokuhlola emkhakheni we-quark, nokho, kuncane kakhulu ukukhiqiza i-asymmetry elinganiselwe ye-quark-sector. Universe. Ngakho-ke ukuqonda ukwephulwa kwe-CP emkhakheni we-lepton kuyintshisekelo ekhethekile kuma-Physicists ukuqonda ubukhona be Universe. Ukwephulwa kwe-CP kumkhakha we-lepton kungasetshenziswa ukuchaza i-asymmetry yendaba-antimatter ngenqubo ebizwa nge-leptogenesis (2).

Kungani i-neutrinos ibalulekile?

I-Neutrinos ziyizinhlayiya ezincane kunazo zonke, ezinkulu zeMvelo ezingenashaji kagesi eyiziro. Ukungathathi hlangothi ngogesi, neutrinos azikwazi ukuba nokusebenzisana kuka-electromagnetic, futhi azinakho ukusebenzisana okuqinile futhi. Ama-neutrino anesisindo esincane sokuhleleka kuka-0.1 eV (~ 2 × 10-³⁷kg), yingakho ukusebenzisana kwamandla adonsela phansi nakho kubuthaka kakhulu. Indlela kuphela neutrinos ingasebenzisana nezinye izinhlayiya kungokusebenzisana okubuthakathaka kwebanga elifushane.

Lesi sakhiwo esisebenzisana kahle se- neutrinos, nokho, ibenza babe uphenyo oluthakazelisayo lokufunda izinto ezikude zezinkanyezi. Nakuba ngisho nama-photon angafihlwa, ahlakazwe futhi ahlakazwe uthuli, izinhlayiya zegesi nemisebe yangemuva ekhona endaweni ephakathi kwezinkanyezi, neutrinos ingadlula kakhulu ngaphandle kokuvinjwa futhi ifinyelele kuma-detectors asekelwe eMhlabeni. Esimeni samanje, ukusebenzisana okubuthakathaka, i-neutrino-sector ingaba ikhandidethi elisebenzayo elifaka isandla ekwephuleni kwe-CP.

I-Neutrino oscillation kanye nokwephulwa kwe-CP

Kunezinhlobo ezintathu ze-neutrinos (𝜈) - 𝜈_𝑒, 𝜈_𝜇 futhi 𝜈_𝜏 - eyodwa ehlotshaniswa ne-lepton flavour ngayinye i-electron (e), i-muon (𝜇) ne-tau (𝜏). Ama-neutrino akhiqizwa futhi atholwa njengama-flavour-eigenstates ngokusebenzisana okubuthakathaka ngokuhambisana ne-lepton eshajiwe yokunambitheka okuhambisanayo, kuyilapho asakazeka njengezifunda ngoquqaba oluqondile, olubizwa ngokuthi i-mass-eigenstates. Ngakho-ke i-neutrino beam yokunambitheka okuqinisekile emthonjeni iba inhlanganisela yakho konke okuthathu okuhlukahlukene okuhlukahlukene lapho kutholwa khona ngemva kokuhamba ngobude bendlela ethile - ingxenye yezinambitheka ezihlukene incike kumapharamitha wesistimu. Lesi simo saziwa ngokuthi yi-neutrino oscillation, okwenza lezi zinhlayiya ezincane zikhetheke kakhulu!

Ngokwethiyori, ngayinye ye-neutrino flavour-eigenstates ingavezwa njengenhlanganisela yomugqa wawo wonke ama-mass-eigenstates amathathu kanye nokuphambene futhi ukuxuba kungachazwa nge-matrix eyodwa ebizwa ngokuthi i-Pontecorvo-Maki-Nakagawa-Sakata (PMNS) matrix (3,4 ,3). Le matrix yokuxuba ehlangene engu-XNUMX-dimensional ingenziwa ipharamitha ngama-engeli amathathu okuxutshwa nezigaba eziyinkimbinkimbi. Kulezi zigaba eziyinkimbinkimbi, i-neutrino oscillation izwela esigabeni esisodwa kuphela, esiqanjwe ngokuthi 𝛿_𝐶𝑃, futhi iwumthombo oyingqayizivele wokwephulwa kwe-CP kumkhakha we-lepton. 𝛿_𝐶𝑃 ingathatha noma yiliphi inani kububanzi −180° no-180°. Ngenkathi 𝛿_𝐶𝑃=0,±180° kusho ukuthi ama-neutrino nama-antiutrino aziphatha ngokufanayo futhi i-CP iyongiwa, 𝛿_𝐶𝑃=±90° ikhombisa ukwephulwa kwe-CP okuphezulu kumkhakha we-lepton we-Standard Model. Noma yiliphi inani elimaphakathi libonisa ukwephulwa kwe-CP ngamadigri ahlukene. Ngakho-ke isilinganiso sika 𝛿_𝐶𝑃 ingenye yezinhloso ezibaluleke kakhulu zomphakathi we-neutrino physics.

Ukulinganisa amapharamitha we-oscillation

Ama-neutrino akhiqizwa ngobuningi ngesikhathi sokusabela kwenyukliya, njengalawo ase-Sun, ezinye izinkanyezi kanye ne-supernovae. Akhiqizwa futhi emkhathini woMhlaba ngokusebenzisana kwemisebe ye-cosmic enamandla amakhulu namanuclei e-athomu. Ukuze ube nombono we-neutrino flux, cishe izigidigidi eziyi-100 zidlula kithi njalo ngomzuzwana. Kodwa asikuqondi nokukuqaphela njengoba besebenzisa kabi kakhulu. Lokhu kwenza ukukalwa kwezakhiwo ze-neutrino ngesikhathi sokuhlolwa kwe-neutrino oscillation kube umsebenzi oyinselele ngempela!

Ukulinganisa lezi zinhlayiya ezingatholakali kalula, izithungatha ze-neutrino zinkulu, zinamakhilogremu obunzima futhi ukuhlola kuthatha iminyaka embalwa ukuzuza imiphumela ebalulekile ngokwezibalo. Ngenxa yokusebenzelana kwabo okubuthakathaka, kwathatha ososayensi cishe iminyaka engama-25 ukuthola i-neutrino yokuqala ngokuhlolwa ngemva kokuba u-Pauli eveze ukuba khona kwayo ngo-1932 ukuze achaze ukongiwa komfutho wamandla ekuboleni kwe-nuclear beta (eboniswe emfanekisweni (5)).

Ososayensi balinganise womathathu ama-engeli okuxuba ngokunemba okungaphezu kuka-90% kokuzethemba okungu-99.73% (3𝜎) (6). Ama-engeli amabili okuxuba makhulu ukuchaza ukuzungeza kwe-solar neutrinos yasemkhathini, i-engeli yesithathu (eqanjwe 𝜃₁₃) lincane, inani elilingana kahle kakhulu lilinganiselwa ku-8.6°, futhi likalwa ngokokuhlola kamuva nje ngo-2011 ngokuhlolwa kwe-reactor neutrino i-Daya-Bay e-China. Kumatrix we-PMNS, isigaba 𝛿_𝐶𝑃 ibonakala kuphela kunhlanganisela yesono𝜃₁₃𝑒^{±𝑖𝛿_𝐶𝑃,} ukwenza ukulinganisa kokuhlola kwe-𝛿_𝐶𝑃 kunzima.

Ipharamitha ebala inani lokuphulwa kwe-CP kokubili kumkhakha we-quark kanye ne-neutrino ibizwa ngokuthi i-Jarlskog invariant 𝐽_𝐶𝑃 (7), okuwumsebenzi wokuxuba ama-engeli kanye nesigaba sokwephulwa kwe-CP. Okomkhakha we-quark 𝐽_𝐶𝑃~3×10^-5 , ngenkathi kumkhakha we-neutrino 𝐽_𝐶𝑃~0.033 isono𝛿_𝐶𝑃, futhi ngaleyo ndlela ingaba ama-oda amathathu obukhulu amakhulu kuno-𝐽_𝐶𝑃 emkhakheni we-quark, kuye ngevelu ethi 𝛿_𝐶𝑃.

Umphumela ovela ku-T2K - inkomba ekuxazululeni impicabadala ye-asymmetry ye-matter-antimatter

Ocwaningweni olude lwesisekelo se-neutrino oscillation T2K (Tokai-to-Kamioka e-Japan), imishayo ye-neutrino noma ye-antineutrino ikhiqizwa e-Japan Proton Accelerator Research Complex (J-PARC) futhi itholwa kumtshina we-Water-Cerenkov e-Super-Kamiokande, ngemuva kokuhamba ibanga elingu-295km eMhlabeni. Njengoba lesi sisheshisi singakhiqiza imishayo ye-𝜈_𝜇 noma i-antiparticle yayo 𝜈̅𝜇, futhi umtshina ungabona 𝜈_𝜇,𝜈_𝑒 kanye nama-antiparticles awo 𝜈̅𝜇, 𝜈̅𝑒, anemiphumela evela ezinqubweni ezine ezihlukene ze-oscillation futhi angenza ukuhlaziya ukuze athole imingcele esebenza kahle kumapharamitha wokuzulazula. Nokho, isigaba sokwephulwa kwe-CP 𝛿_𝐶𝑃 ibonakala kuphela ngenqubo lapho i-neutrinos ishintsha ukunambitheka okungukuthi kuma-oscillations 𝜈𝜇→𝜈𝑒 kanye 𝜈̅𝜇→𝜈̅𝑒 - noma yimuphi umehluko kulezi zinqubo ezimbili ungasho ukwephulwa kwe-CP kumkhakha we-lepton.

Ekuxhumaneni kwakamuva, ukusebenzisana kwe-T2K kubike imingcele ethokozisayo yokwephulwa kwe-CP emkhakheni we-neutrino, ukuhlaziya idatha eqoqwe phakathi kuka-2009 no-2018 (8). Lo mphumela omusha ukhiphe umthetho wokuthi cishe u-42% wawo wonke amanani angaba khona okuthi 𝛿_𝐶𝑃. Okubaluleke nakakhulu, icala lapho i-CP yongiwa ikhishwe ngokuzethemba okungu-95%, futhi ngesikhathi esifanayo ukwephulwa kwe-CP okukhulu kubonakala kukhethwa kuMvelo.

Emkhakheni we-high-energy physics, ukuzethemba okungu-5𝜎 (okungu-99.999%) kuyadingeka ukuze ufune ukutholwa okusha, ngakho-ke ukuhlolwa kwesizukulwane esilandelayo kuyadingeka ukuze uthole izibalo ezanele kanye nokunemba okuphezulu ukuze kutholwe isigaba sokwephulwa kwe-CP. Nokho umphumela wakamuva we-T2K uwukuthuthuka okubalulekile ekuqondeni kwethu i-asymmetry ye-matter-antimatter ye- Universe ngokwephulwa kwe-CP emkhakheni we-neutrino, okokuqala ngqa.

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References:

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2. Bari Pasquale Di, 2012. Isingeniso se-leptogenesis kanye ne-neutrino properties. I-Contemporary Physics Volume 53, 2012 - Issue 4 Amakhasi 315-338. I-DOI: https://doi.org/10.1080/00107514.2012.701096

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6. Tanabashi M., et al. (I-Particle Data Group), 2018. Izixuku ze-Neutrino, Ukuxuba, kanye ne-Oscillations, i-Phys. Umfundisi D98, 030001 (2018) kanye nesibuyekezo sika-2019. I-DOI: https://doi.org/10.1103/PhysRevD.98.030001

7. Jarlskog, C., 1986. UJarlskog Uyaphendula. Phys. Umfundisi Lett. 57, 2875. DOI: https://doi.org/10.1103/PhysRevLett.57.2875

8. Ukusebenzisana kwe-T2K, 2020. Umkhawulo odabeni–isigaba sokwephulwa kwe-antimatter symmetry ku-oscillations ye-neutrino. Ivolumu yemvelo 580, amakhasi339–344(2020). Kushicilelwe: 15 Ephreli 2020. DOI: https://doi.org/10.1038/s41586-020-2177-0

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