There are a number of puzzles of beyond the standard model physics that can be probed directly by the process of neutron-anti-neutron oscillation in contrast with the othetr popular baryon violating process i.e. the typical GUT motivated proton decay mode $p\rightarrow e^+ π^0$. The most important of them is a direct understanding of the baryon asymmetry of the universe on which the typical...
We discuss models that can feature $n-\bar n$ oscillations at observable
levels. These are extra-dimensional theories with Standard-Model fermions
propagating in the extra dimensions. Interestingly, while proton decay can
be suppressed well below experimental limits in these models, $n-\bar n$
oscillations can occur at levels comparable to current limits. Thus,
in these theories,...
The European Spallation Source ESS, presently under construction, in Lund, Sweden, is a multi-disciplinary international laboratory. It will operate the world's most powerful pulsed neutron source. Taking advantage of the unique potential of the ESS, the NNBAR collaboration proposed a two-stage program of experiments to perform high precision searches for neutron conversion in a range of...
As a baryon number violating process with $\Delta B = \Delta (B−L) = 2$, neutron-antineutron oscillation ($n\to\bar n$)provides an important candidate and a unique probe to the baryon asymmetry. We performed a search for $n\to\bar n$ oscillation with the Super-Kamiokande (SK) experiment. Full exposure data set of SK was analyzed using a multi-variate analysis based on kinematic variables and...
The Deep Underground Neutrino Experiment (DUNE) utilizes Liquid Argon Time Projection Chamber (LArTPC) technology to deeply probe $\nu$ and beyond Standard Model (BSM) interactions with great granularity. The DUNE Technical Design Report (TDR) prioritizes BSM searches for baryon number violation (BNV) modes such as proton decay and neutron-antineutron transformation ($n\rightarrow\bar{n}$),...
Neutron-antineutron oscillations can survive sufficiently coherent interactions with matter and external fields without suppressing the oscillation rate. I describe some examples of this phenomenon which might find practical applications
in the design of future experiments.
I discuss a framework based on chiral effective filed theory for treating baryon-number violation by two units in nuclei. The deuteron lifetime is used as an application to illustrate this framework. The emphasis is given to how a consistent power counting is built and what statements can be drawn out of it.
I review and revisit the calculation of the lifetime of nuclei due to neutron-antineutron oscillations.
It is stressed that the oscillation and the subsequent annihilation take place mainly outside the nucleus and thus hardly suffer from drastic renormalization due to the nuclear medium. The ingredients of the calculation can be safely extracted from nuclear shell-model wave-functions, and...
The following questions are often raised when discussing the neutron-antineutron oscillations nuclei:
- How well is known the nucleon-antinucleon interaction?
- How well is known the antinucleon-nucleus interaction?
- Is the shell model an appropriate tool?
- How comes that the neutron-antineutron oscillation takes place mainly at the surface of the nucleus?
- What type of final...
Theories of B-L violation beyond the Standard Model (BSM) generically lead to the appearance of six-quark operators in Standard Model effective field theory that give rise to neutron-antineutron oscillations and Delta B = 2 nuclear decays. Reliably connecting the results of experimental searches for these processes to constraints on the parameters of BSM physics theories requires Standard...
Post-sphaleron baryogenesis (PSB) is an attractive low-scale mechanism to explain the observed matter-antimatter asymmetry of the Universe. The same \Delta B=2 operator that gives rise to baryogenesis in this scenario also leads to neutron-antineutron oscillation. We show that the PSB mechanism, when embedded in a quark-lepton unified model based on the Pati-Salam gauge group, leads to an...
$n-\bar{n}$ oscillations can be used to probe theories at a high energy scale, such as grand unified theories. In this talk I will illustrate this with two examples. In the first example, $n-\bar{n}$ oscillation arises in a left-right symmetric model realized near the GUT scale that provides a solution to the strong CP problem. The $n-\bar{n}$ oscillation time is closely tied to neutrino...
Wherein I discuss how improvements on neutron-antineutron oscillations and its impact on a minimal theory of baryogenesis.
The scheme of the experiment on search for neutron-antineutron oscillations based on the storage of ultracold neutrons in a material trap is presented. The idea of such an experiment becomes important due to creation of new powerful UCN sources. The sensitivity of the experiment was obtained in Monte Carlo simulation of UCN transport and storage. It mostly depends on the trap size and the...
Existing bounds on the neutron-antineutron mass mixing, $\epsilon_{n\bar n} < {\rm few} \times 10^{-24}$~eV, impose a severe upper limit on $n - \bar n$ transition probability, $P_{n\bar n}(t) < (t/0.1 ~{\rm s})^2 \times 10^{-18}$ or so, where $t$ is the neutron flight time. Here we propose a new mechanism of $n- \bar n$ transition which is not induced by direct mass mixing $\epsilon_{n\bar...
As follows from theoretical conjectures of Z. Berezhiani et al. [2006-2020] the neutron that is part of the Standard Model ($SM$) can oscillate into sterile state $ n \rightarrow n^{'} $ , thus leading to neutron disappearance or baryon number violation $ \Delta B=-1 $. However, this can be only an apparent disappearance: if the sterile neutron $ n^{'}~ $ is part of the Mirror Standard Model...
Oak Ridge National Laboratory has some of the world’s most advanced neutron sources, the High Flux Isotope Reactor (HFIR) which is a continuous source of neutrons from nuclear fission, and the Spallation Neutron Source, a pulsed source created by an accelerated proton beam hitting a mercury target. Not only are both good sources for neutrons, they are also excellent neutrino sources with...
In many models of new physics, the expected rate of processes that break
baryon number by two units rests on the features of a poorly known
scalar sector, whose members can carry B or L quantum numbers. Thus
the BNV discovery prospects in these channels are controlled by the extent
to which the associated scalars are excluded by experiments. Working
in the context of minimal scalar...
Baryon number violation is an extremely sensitive probe of physics beyond the Standard Model. However, the continued absence of any signals raises the question if we are actually looking in the right places or if we should broaden our search strategies. In this talk I will propose inclusive nucleon decay searches as a convenient method to cover a lot of parameter space, including sensitivity...
Couplings between neutrons and a mirror sector can be formulated in terms of observable effects for precession-measurements (as has been pointed out by Berezhiani), bringing to bear the tools and experimental resources already in play for the measurement of static electric dipole moments.limits for measurements with the coupling strength for neutrons to mirror neutrons. Some details of...
Proton decay can be sufficiently suppressed in an extra-dimensional model where Standard-Model (SM) fermions are localized at different points in the extra dimension(s), whereas $n$-$\bar n$ oscillations can occur at a rate comparable to the current observable limit. We show that in a left-right symmetric model with extra dimensions this effect is even more enhanced. Several nucleon and...
In this talk I discuss baryon number violation and the relationship between processes that violate it by one or two units. While proton decay searches currently probe baryon number violation by one unit up to very high scales, those that violate it by two units can be directly motivated by the baryon asymmetry of the universe and can be the leading baryon number violating signal in some...
$n-\bar{n}$ oscillations can be used to probe theories at a high energy scale, such as grand unified theories. In this talk I will illustrate this with two examples. In the first example, $n-\bar{n}$ oscillation arises in a left-right symmetric model realized near the GUT scale that provides a solution to the strong CP problem. The $n-\bar{n}$ oscillation time is closely tied to neutrino...