User:Mauro.mezzetto/sandbox

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User:Mauro.mezzetto/sandbox

← Previous revision Revision as of 11:17, 20 April 2026
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which relates the time \textstyle \tau_m to have the production of an antineutron that immediately annihilates to the oscillation time \textstyle \tau_{n\bar n}. The quantity ''R,'' which dimension is s-1, depends from the nucleus, cannot be derived from first principles and ...
which relates the time \textstyle \tau_m to have the production of an antineutron that immediately annihilates to the oscillation time \textstyle \tau_{n\bar n}. The quantity ''R,'' which dimension is s-1, depends from the nucleus, cannot be derived from first principles and ...


overall theoretical uncertainty for these one-nucleon processes is approximately '''10%–15%'''. While these improvements cover one-nucleon processes, the authors note an additional '''15%–30% systematic uncertainty''' related to '''two-nucleon processes''' inside the nucleus, which could compete with the leading mode.{{Cite journal |last=Dover |first=C. B. |last2=Gal |first2=A. |last3=Richard |first3=J. M. |date=1983-03-01 |title=Neutron-antineutron oscillations in nuclei |url=https://doi.org/10.1103/physrevd.27.1090 |journal=Physical Review D |volume=27 |issue=5 |pages=1090–1100 |doi=10.1103/physrevd.27.1090 |issn=0556-2821}}{{Cite journal |last=Dover |first=C.B. |last2=Gal |first2=A. |last3=Richard |first3=J.M. |date=1989-11 |title=Neutron-antineutron oscillations in nuclei |url=https://doi.org/10.1016/0168-9002(89)90239-8 |journal=Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment |volume=284 |issue=1 |pages=13–15 |doi=10.1016/0168-9002(89)90239-8 |issn=0168-9002}} This value represents a significant reduction compared to the '''50%–100% uncertainty range''' common in calculations from the 1980s and 1990s. The most critical factor in reducing systematic error is the use of extensive and precise data from '''antiprotonic ('''''p''ˉ​''') atoms''' that became available after the earlier calculations were published.
overall theoretical uncertainty for these one-nucleon processes is approximately '''10%–15%'''. This value represents a significant reduction compared to the '''50%–100% uncertainty range''' common in calculations from the 1980s and 1990s. While these improvements cover one-nucleon processes, an additional '''15%–30% systematic uncertainty''' related to '''two-nucleon processes''' inside the nucleus, should be taken into consideration.{{Cite journal |last=Dover |first=C. B. |last2=Gal |first2=A. |last3=Richard |first3=J. M. |date=1983-03-01 |title=Neutron-antineutron oscillations in nuclei |url=https://doi.org/10.1103/physrevd.27.1090 |journal=Physical Review D |volume=27 |issue=5 |pages=1090–1100 |doi=10.1103/physrevd.27.1090 |issn=0556-2821}}{{Cite journal |last=Dover |first=C.B. |last2=Gal |first2=A. |last3=Richard |first3=J.M. |date=1989-11 |title=Neutron-antineutron oscillations in nuclei |url=https://doi.org/10.1016/0168-9002(89)90239-8 |journal=Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment |volume=284 |issue=1 |pages=13–15 |doi=10.1016/0168-9002(89)90239-8 |issn=0168-9002}} The most critical factor in reducing systematic error is the use of extensive and precise data from '''antiprotonic ('''''p''ˉ​''') atoms''' that became available after the earlier calculations were published.{{Cite journal |last=Friedman |first=E. |last2=Gal |first2=A. |last3=Mareš |first3=J. |date=2005-11 |title=Antiproton–nucleus potentials from global fits to antiprotonic X-rays and radiochemical data |url=https://doi.org/10.1016/j.nuclphysa.2005.08.001 |journal=Nuclear Physics A |volume=761 |issue=3-4 |pages=283–295 |doi=10.1016/j.nuclphysa.2005.08.001 |issn=0375-9474}}


== Experimental searches ==
== Experimental searches ==
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To keep the observation time as long as possible experiments using free neutron beams must shield the propagation region as
To keep the observation time as long as possible experiments using free neutron beams must shield the propagation region as


{| class="wikitable sortable"
{| class="wikitable"
|+ Caption della tabella (titolo principale)
! Year
! Year
! Nucleus
! Nucleus
! Experiment
! Experiment
!{{math|τ}}m (1032 yr)
! Value 1
! Value 2
! R
! tnn (108 s)
! Value 3


|-
|-
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| IMB {{Cite journal |last=Jones |first=T. W. |display-authors=1 |date=1984-02-27 |title=Search for n − n ¯ Oscillation in Oxygen |url=https://aps.org |journal=Physical Review Letters |volume=52 |issue=9 |pages=720–723 |doi=10.1103/PhysRevLett.52.720}}
| IMB {{Cite journal |last=Jones |first=T. W. |display-authors=1 |date=1984-02-27 |title=Search for n − n ¯ Oscillation in Oxygen |url=https://aps.org |journal=Physical Review Letters |volume=52 |issue=9 |pages=720–723 |doi=10.1103/PhysRevLett.52.720}}
| 0.2
| 0.24


| 0.517
| 0.52
| 1.2
| 1.2
|-
|-
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| 0.4
| 0.4


| 0.517
| 0.52
| 1.6
| 1.6
|-
|-
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| 1.9
| 1.9


| 0.517
| 0.52
| 3.4
| 3.4
|-
|-
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| 3.6
| 3.6


| 0.517
| 0.52
| 4.7
| 4.7
|}
|}

Scaling HK 7 1032 yr, DUNE:
Scaling HK 7 1032 yr, DUNE:


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== Theoretical motivation ==
== Theoretical motivation ==


At the quark level, the \textstyle n-\bar{n} transition is (udd) → (ucdcdc ). This is mediated by six-quark operators MX which have dimension 9 in mass units, and the process
At the quark level, the \textstyle n-\bar{n} transition is (udd) → (ucdcdc ). This is mediated by six-quark operators MX which have dimension 9 in mass units, and the process. Since each of the six fermion fields contributes a mass dimension of 3/2 to the Lagrangian, the transition amplitude has dimension 9 in mass units and scales as M−5, where M is the scale of (B−L) violation. An experiment sensitive to tnn=198s probes an energy scale of about 105 GeV.





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