Explore the vast range of titles available.

We give minireview of nonlocal field theory (infinite derivative field theory). We start with the discussion of the main peculiarities of nonlocal field theory on the example of scalar -model. The nonlocal -model is ultraviolet finite, unitary, and macrocausal. One of the problems of nonlocal field theory is that the formfactor is an arbitrary entire function that makes the predictions extremely weak. We propose some additional principle that allows to fix the formfactor. Also we review the main results obtained in nonlocal quantum gravity, namely the nonlocal generalization of Einstein gravity leads to the superrenormalizable theory.

We consider the SM extension with additional light real singlet scalar, right-handed neutrino and nonrenormalizable Yukawa interaction for the first two generations. We show that the proposed model can explain the observed (g – 2) muon anomaly. Phenomenological consequenses as flavour violating decays τ → μμμ, μμe, μee are briefly discussed. We also propose the UR(1) gauge generalization of the SM with complex scalar singlet and nonzero right-handed charges for the first two generations.

We present a brief review of the SUc(3)⊗SUL(2)⊗SUR(2)⊗U(1) left-right symmetric gauge model. We discuss a possibility of detecting the right-handed WR boson and a heavy neutrino in pp collisions at the Large Hadron Collider. We present restrictions on the masses of the WR boson and the heavy neutrino obtained using the analysis of experimental data from the CMS and ATLAS detectors with a total energy of colliding protons of 7–8 TeV.

Millicharged particles emerge as compelling candidates in numerous theoretically well-motivated extensions of the Standard Model. These hypothetical particles, characterized by an electric charge that is a small fraction of the elementary charge, have attracted significant attention in contemporary experimental physics. Their potential existence motivates dedicated search strategies across multiple experimental platforms, leveraging their distinctive electromagnetic interactions while evading conventional detection methods. In the present paper we estimated the projected sensitivity of fixed-target experiments, specifically NA64 μ and LDMX, to the parameter space of millicharged particles. For the NA64 μ experiment, with an anticipated muon flux of MOT ≲ 10 14 , our analysis reveals a detectable mass window of 10 MeV ≲ m χ ≲ 150 MeV and charge parameter range 10 - 4 ≲ ϵ ≲ 7 × 10 - 4 . This sensitivity arises from the bremsstrahlung-like missing energy signature μ N → μ N γ ∗ ( → χ χ ¯ ) . Furthermore, we evaluate the discovery potential of the LDMX facility, considering its projected electron beam statistics, EOT ≲ 2 × 10 16 , and energy, E e ≃ 8 GeV . Our results demonstrate that LDMX can probe heavier MCPs in the mass range 250 MeV ≲ m χ ≲ 400 MeV , with sensitivities reaching 10 - 3 ≲ ϵ ≲ 1.5 × 10 - 3 . This parametric window can be accessible through the distinctive invisible decay channel ρ → χ χ ¯ , where ρ -meson photo-production γ N → N ρ plays a pivotal role.

Mirror matter from the dark hidden sector with the same particle content and gauge interactions as in the standard model is still an interesting candidate for dark matter. Several experiments on search for positronium and neutron oscillations into their mirror partner have been conducted recently. In this work we consider the transitions \\(K^0-K^0_m\\) of a neutral kaon into a hidden mirror kaon. It is shown that their probability can be probed with the sensitivity of \\(P(K^0-K^0_m ) 10^-7\\) from the search for missing-energy events in the NA64 experiment at the CERN SPS with \\( 10^11\\) \\(K^+\\) on target.This would result in a limit on the \\(K^0-K^0_m\\) mixing parameter much stronger than the similar bound estimated from the cosmological considerations.

Millicharged particles emerge as compelling candidates in numerous theoretically well-motivated extensions of the Standard Model. These hypothetical particles, characterized by an electric charge that is a small fraction of the elementary charge, have attracted significant attention in contemporary experimental physics. Their potential existence motivates dedicated search strategies across multiple experimental platforms, leveraging their distinctive electromagnetic interactions while evading conventional detection methods. In the present paper we estimated the projected sensitivity of fixed-target experiments, specifically NA64 μ and LDMX, to the parameter space of millicharged particles. For the NA64 μ experiment, with an anticipated muon flux of MOT≲1014 , our analysis reveals a detectable mass window of 10MeV≲mχ≲150MeV and charge parameter range 10-4≲ϵ≲7×10-4 . This sensitivity arises from the bremsstrahlung-like missing energy signature μN→μNγ∗(→χχ¯) . Furthermore, we evaluate the discovery potential of the LDMX facility, considering its projected electron beam statistics, EOT≲2×1016 , and energy, Ee≃8GeV . Our results demonstrate that LDMX can probe heavier MCPs in the mass range 250MeV≲mχ≲400MeV , with sensitivities reaching 10-3≲ϵ≲1.5×10-3 . This parametric window can be accessible through the distinctive invisible decay channel ρ→χχ¯ , where ρ -meson photo-production γN→Nρ plays a pivotal role.

We show that in nonlocal generalization of standard nonsupersymmetric SU(5) GUT it is possible to solve the problems with the proton lifetime and the Weinberg angle without introduction of additional particles in the spectrum of the theory. Non-local scale responsible for ultraviolet cutoff coincides (up to some factor) with GUT scale. We find that in the simplest nonlocal modification of the SU(5) model \\(M_{\\rm GUT} = 3 * 10^{16}\\) GeV . In general case the value of M_GUT is an arbitrary and the most interesting option \\(M_{\\rm GUT} = O(M_{\\rm PL})\\) could be realized.

A bstract The inclusion of an additional U(1) gauge L μ − L τ symmetry would release the tension between the measured and the predicted value of the anomalous muon magnetic moment: this paradigm assumes the existence of a new, light Z ′ vector boson, with dominant coupling to μ and τ leptons and interacting with electrons via a loop mechanism. The L μ − L τ model can also explain the Dark Matter relic abundance, by assuming that the Z ′ boson acts as a “portal” to a new Dark Sector of particles in Nature, not charged under known interactions. In this work we present the results of the Z ′ search performed by the NA64- e experiment at CERN SPS, that collected ~ 9 × 10 11 100 GeV electrons impinging on an active thick target. Despite the suppressed Z ′ production yield with an electron beam, NA64- e provides the first accelerator-based results excluding the g − 2 preferred band of the Z ′ parameter space in the 1 keV < m Z ′ ≲ 2 MeV range, in complementarity with the limits recently obtained by the NA64- μ experiment with a muon beam.

We describe the search for new physics to be performed at the Large Hadron Collider.

Abstract Millicharged particles emerge as compelling candidates in numerous theoretically well-motivated extensions of the Standard Model. These hypothetical particles, characterized by an electric charge that is a small fraction of the elementary charge, have attracted significant attention in contemporary experimental physics. Their potential existence motivates dedicated search strategies across multiple experimental platforms, leveraging their distinctive electromagnetic interactions while evading conventional detection methods. In the present paper we estimated the projected sensitivity of fixed-target experiments, specifically NA64$$\\mu $$μ and LDMX, to the parameter space of millicharged particles. For the NA64$$\\mu $$μ experiment, with an anticipated muon flux of$$\\text{ MOT }\\lesssim 10^{14}$$MOT ≲ 10 14 , our analysis reveals a detectable mass window of$$10~\\text{ MeV } \\lesssim m_\\chi \\lesssim 150~\\text{ MeV }$$10 MeV ≲ m χ ≲ 150 MeV and charge parameter range$$10^{-4} \\lesssim \\epsilon \\lesssim 7\\times 10^{-4}$$10 - 4 ≲ ϵ ≲ 7 × 10 - 4 . This sensitivity arises from the bremsstrahlung-like missing energy signature$$\\mu N \\rightarrow \\mu N \\gamma ^{*}( \\rightarrow \\chi \\bar{\\chi })$$μ N → μ N γ ∗ ( → χ χ ¯ ) . Furthermore, we evaluate the discovery potential of the LDMX facility, considering its projected electron beam statistics,$$\\text{ EOT }\\lesssim 2\\times 10^{16}$$EOT ≲ 2 × 10 16 , and energy,$$E_\\textrm{e}\\simeq 8~\\text{ GeV }$$E e ≃ 8 GeV . Our results demonstrate that LDMX can probe heavier MCPs in the mass range$$250~\\text{ MeV } \\lesssim m_\\chi \\lesssim 400 ~\\text{ MeV }$$250 MeV ≲ m χ ≲ 400 MeV , with sensitivities reaching$$10^{-3} \\lesssim \\epsilon \\lesssim 1.5 \\times 10^{-3}$$10 - 3 ≲ ϵ ≲ 1.5 × 10 - 3 . This parametric window can be accessible through the distinctive invisible decay channel$$\\rho \\rightarrow \\chi \\bar{\\chi }$$ρ → χ χ ¯ , where$$\\rho $$ρ -meson photo-production$$\\gamma N \\rightarrow N \\rho $$γ N → N ρ plays a pivotal role.