E B Holzer’s research while affiliated with CERN and other places

... An interpretation of the results in a dark photon model are given in Fig. 19. This includes the initial sensitivity of FASER with a track-based analysis [9] as discussed in Appendix A. Additionally, search results from NA62 [115], NA64 [116], NuCal [93,117] and E141 [118,119] are shown. ...

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Shining Light on the Dark Sector: Search for Axion-like Particles and Other New Physics in Photonic Final States with FASER

... This additional magnet spectrometer also reduces the background from in-flight kaons decays given a shorter distance to the target by a factor ∼ 10 −1 . It is worth noting that this background could be further reduced and controlled by proper identification of kaons along the beam-line through the use of Cherenkov counter with achromatic ring focus (CEDAR) [111]. Finally, the computations of the projected limits assume a reduction of the background related to non-hermeticity of the detectors'. ...

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Shedding light on Dark Sectors with high-energy muons at the NA64 experiment at the CERN SPS

... The ALP-gluon limits in comparison with results from NA62 [90][91][92], BaBar [74], flavour constraints [20], NuCal [20,93], CHARM [94], NA48 [95,96], E949 [97][98][99] and from the total decay width of the kaon [96] are shown in Fig. 17(c). Fig. 18(a) displays the existing constraints for the U(1) B model in comparison to the FASER limit presented. ...

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Shining Light on the Dark Sector: Search for Axion-like Particles and Other New Physics in Photonic Final States with FASER

... There are specific observables in the kaon sector that have been under intense experimental scrutiny to further augment our understanding of the Standard Model (SM). They include the golden channels: BR(K + → π + νν) at NA62 [1] and BR(K L → π 0 νν) at KOTO [2,3], the rare decay modes BR(K + → π + µμ) at NA62 [4] and K S → µµ at LHCb [5]. These analyses were preceded by several past endeavours that is inclusive of those at E865 [6] and NA48/2 [7] for BR(K + → π + eē) and at NA48/2 [8] for BR(K + → π + µμ). ...

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Theoretical implications for a new measurement of $K_L\to \pi^0 \ell\ell

... Thanks to the multiple trigger lines [3] and the versatility of the experiment, besides the + → +¯, multiple + decays can be studied. Other NA62 recent results are published in [4] and [5]. ...

Reference:

Recent Results from Precision Measurements at the NA62 Experiment

... In the same regime however, the two electrons produced by the new particle decay will carry each E ∼ m X /2, allowing a larger fraction to pass the momentum cut. B v 2 H a K q j o g Q u H c + 7 l 3 n u C i D N t f P / N S / X 1 D w w O D Y + k R 8 f G J y Y z U 9 M l H V p F a J G E P F T l A G v K m a R F w w y n 5 U h R L A J O j 4 P z v Y 5 / f E G V Z q E 8 M u 2 I 1 g R u S d Z k B B s n 1 T N z V 8 V 6 f F A V N r k 6 W Y e 7 s C q t i O k a Q k k 9 s + x n / S 6 g n 8 3 l N t D G l i O b O z m E t i H 6 t J b z i w u n q d v Z x 0 I 9 8 1 5 t h M Q K K g 3 h W O s K 8 i N T i 7 E y j H C a p K t W 0 w i T c 9 y i F U c l F l T X 4 u 4 L C V x x S g M 2 Q + V K G t h V v 0 / E W G j d F o H r F N i c 6 d 9 e R / z L q 1 j T 3 K 7 F T E b W U E l 6 i 5 q W Q x P C T h 6 w w R Q l h r c d w U Q x d y s k Z 1 h h Y l x q P 7 Z o Z i U z l 0 n a J f P 1 P v y f l N a z a We consider the secondary muon flux produced at NA62 in dump mode [62], which has been simulated in Ref. [42]. The idea is that the muons could decay in flight to an ALP plus electron, for which we saturate the branching limit BR (µ → e + inv.) ≤ 2.6 × 10 −6 from Jodidio et.al. ...

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Displaced Searches for Axion-Like Particles and Heavy Neutral Leptons at Mu3e

... A two-level trigger system is used, comprising a hardware low level trigger (L0) and a software high level trigger (L1) [20]. The main trigger line is dedicated to the K + → π + νν study. ...

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First detection of a tagged neutrino in the NA62 experiment

... Although no signs of LN or LF violation are observed, these results set the current world's most stringent upper limits (UL) on the branching ratios, improving considerably over the previous best results. Of particular Decay channel Previous BR UL [8] NA62 BR UL Improvement + → − + + 8.6 × 10 −11 4.2 × 10 −11 [9] ∼ factor 2 + → − + + 6.4 × 10 −10 5.3 × 10 −11 [10] ∼ factor 12 [10] first search + → − + + 5.0 × 10 −10 4.2 × 10 −11 [11] ∼ factor 12 + → + − + 5.2 × 10 −10 6.6 × 10 −11 [11] ∼ factor 8 [12] ∼ factor 250 interest is the channel + → − + + ( ), which can violate LN or LF depending on the flavor of the neutrino in the final state. The only previous search for this process dates back to the Geneva-Saclay experiment in 1976 [7]. ...

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Physics beyond the Standard Model with the NA62 experiment at CERN

... Thanks to the multiple trigger lines [3] and the versatility of the experiment, besides the + → +¯, multiple + decays can be studied. Other NA62 recent results are published in [4] and [5]. ...

Reference:

Recent Results from Precision Measurements at the NA62 Experiment

... The model can be tested by the current and future measurements of various flavor experiments like Kaon rare decays, in addition to high energy collider experiments as well as gravitational wave observations. For example, top-charm mixing and its CP violating phase are important parameters to test the model via the signals at direct search experiments [49][50][51][52][53][54][55] and various transition processes of K mesons and B mesons [56][57][58][59][60][61][62][63][64]. In particular, they would be testable via the golden modes K → πνν [65,66] at KOTO experiment at J-PARK [62,67] and NA62 experiment at the CERN SPS [63,64]. ...

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Electroweak baryogenesis via top-charm mixing