Bounding Isotropic Lorentz Violation Using Synchrotron Losses at LEP

Bounding the Tau Neutrino Magnetic Moment from Single Photon Searches at LEP

We show that single photon searches at LEP constrain the tau neutrino magnetic moment to be less than ${\cal O}(10^{-6})~μ_B$. This bound is competitive with low energy ($s\simeq (30~GeV)^2$) single photon searches.

Bounding the Number of Light Neutrinos Species in a Left-Right Symmetric Model

Using the experimental values for the rates $R^{LEP} _{exp}=Γ_{inv}/Γ_{l\bar l}=5.942\pm 0.016$, $R^{Giga-Z_1}=Γ_{inv}/Γ_{l\bar l}=5.942\pm 0.012$ (most conservative) and $R^{Giga-Z_1}=Γ_{inv}/Γ_{l\bar l}=5.942\pm 0.006$ (most optimistic) we derive constraints on the number of neutrinos light species $(N_ν)_{LRSM}$ with the invisible width method in the framework of a left-right symmetric model (LRSM) as a function of the LR mixing angle $ϕ$. Using the LEP result for $N_ν$ we may place a bound on this angle, $-1.6\times 10^{-3}\leqϕ\leq 1.1\times 10^{-3}$, which is stronger than those obtained…

Gravitational mass of positron from LEP synchrotron losses

General relativity (GR) is the current description of gravity in modern physics. One of the cornerstones of GR, as well as Newton's theory of gravity, is the weak equivalence principle (WEP), stating that the trajectory of a freely falling test body is independent of its internal structure and composition. WEP is known to be valid for the normal matter with a high precision. However, due to the rarity of antimatter and weakness of the gravitational forces, the WEP has never been confirmed for antimatter. The current direct bounds on the ratio between the gravitational and inertial masses of th…

Bounding resonant Majorana neutrinos from four-body B and D decays

Searches of lepton-number violation in different processes are very useful to constrain the parameter space of Majorana neutrinos. Here we use available upper bounds on the branching fractions of B^- -> D^0pi^+mu^-mu^- and D^0 -> (pi^-pi^-/K^-pi^-) mu^-mu^- decays to derive constraints on the mass and mixings of Majorana neutrinos by assuming they are produced resonantly in these four-body decays. While the excluded region obtained from B^- decays are competitive with existing limits from three-body D^- and B^- decays, it is shown that experimental improvements on D^0 decays offer a good poten…

Bounding CPT Violation in the Neutral-B System

The feasibility of placing bounds on CPT violation from experiments with neutral-$B$ mesons is examined. We consider situations with uncorrelated mesons and ones with either unboosted or boosted correlated mesons. Analytical expressions valid for small T- and CPT-violating parameters are presented for time-dependent and time-integrated decay rates, and various relevant asymmetries are derived. We use Monte-Carlo simulations to model experimental conditions for a plausible range of CPT-violating parameters. The treatment uses realistic data incorporating background effects, resolutions, and acc…

缪子（同步加速器）离子对撞机上的新物理：覆盖多个能标的 MuSIC

New Physics at the Muon (Synchrotron) Ion Collider: MuSIC for several scales

本文提出 TeV 级缪子束流的 MuSIC 对撞机可超越现有实验极限，在轻子夸克、缪子亲和矢量玻色子、类轴子粒子和重惰性中微子等多种新物理场景中探索从亚 GeV 到数 TeV 的宽能标参数空间。