Recent results of the searches for Supersymmetry in final states with one or two leptons at CMS are presented. Many Supersymmetry scenarios, including the Constrained Minimal Supersymmetric extension of the Standard Model (CMSSM), predict a substantial amount of events containing leptons, while the largest fraction of Standard Model background events -which are QCD interactions -gets strongly reduced by requiring isolated leptons. The analyzed data was taken in 2011 and corresponds to an integrated luminosity of approximately L = 1 fb −1 . The center-of-mass energy of the pp collisions was √ s = 7 TeV.

Measurements of the fine-structure constant α require methods from across subfields and are thus powerful tests of the consistency of theory and experiment in physics. Using the recoil frequency of cesium-133 atoms in a matter-wave interferometer, we recorded the most accurate measurement of the fine-structure constant to date: α = 1/137.035999046(27) at 2.0 × 10 accuracy. Using multiphoton interactions (Bragg diffraction and Bloch oscillations), we demonstrate the largest phase (12 million radians) of any Ramsey-Bordé interferometer and control systematic effects at a level of 0.12 part per billion. Comparison with Penning trap measurements of the electron gyromagnetic anomaly - 2 via the Standard Model of particle physics is now limited by the uncertainty in - 2; a 2.5σ tension rejects dark photons as the reason for the unexplained part of the muon's magnetic moment at a 99% confidence level. Implications for dark-sector candidates and electron substructure may be a sign of physics beyond the Standard Model that warrants further investigation.

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We experimentally and theoretically study the diffraction phase of large-momentum transfer beam splitters in atom interferometers based on Bragg diffraction. We null the diffraction phase and increase the sensitivity of the interferometer by combining Bragg diffraction with Bloch oscillations. We demonstrate agreement between experiment and theory, and a 1500-fold reduction of the diffraction phase, limited by measurement noise. In addition to reduced systematic effects, our interferometer has high contrast with up to 4.4 million radians of phase difference, and a resolution in the fine structure constant of δα/α = 0.25 ppb in 25 hours of integration time.PACS numbers: 03.75. Dg, 37.25.+k, 06.20.Jr, 06.30.Dr Atom interferometers are a direct analogy to optical interferometers, where beam splitters and mirrors send a wave along two different trajectories. When the waves are recombined, they can interfere constructively or destructively, depending upon the phase difference ∆φ accumulated between the paths. In light-pulse atom interferometers, atomic matter waves are coherently split and reflected using atom-photon interactions, which impart photon momenta k to the atoms.In a Ramsey Bordé interferometer, for example, the atom (of mass m) moves away and back along one path while remaining in constant inertial motion along the other path. The phase difference ∆φ = 8ω r T (T is the pulse separation time) is proportional to the kinetic energy, and thus to the recoil frequency ω r = k 2 /(2m). This enables state-of-the-art measurements of the fine structure constant α [1] and will help realize the expected new definition of the kilogram in terms of the Planck constant [2,3]. Using multiphoton Bragg diffraction [4,5] and simultaneous operation of conjugate interferometers [6], the phase difference has been increased to Φ = 16n 2 ω r T (where the factor of 16 arises from taking the phase difference of the two interferometers), and Earth's gravity and vibrations have been canceled. Unfortunately, however, Bragg diffraction causes a diffraction phase [2, 7-9], which has been the largest systematic effect in high-sensitivity atom interferometers using this technique [2]. Here, we study the diffraction phase in detail and show that it can be suppressed and even nulled by introducing Bloch oscillations as shown in Fig. 1 A, B. Bloch oscillations also increase the measured phase shift towhere n > 1. We decrease the influence of diffraction phases by an amount that is considerably larger than the increase in sensitivity and are in fact able to null them by feedback to the laser pulse intensity. With this increase in signal and suppression of diffraction phase systematics, we expect to see improvements in many applications of atom interferometry, such as measuring gravity and inertial effects [10][11][12][13]

Bragg diffraction has been used in atom interferometers because it allows signal enhancement through multiphoton momentum transfer and suppression of systematics by not changing the internal state of atoms. Its multi-port nature, however, can lead to parasitic interferometers, allows for intensity-dependent phase shifts in the primary interferometers, and distorts the ellipses used for phase extraction. We study and suppress these unwanted effects. Specifically, phase extraction by ellipse fitting and the resulting systematic phase shifts are calculated by Monte Carlo simulations. Phase shifts arising from the thermal motion of the atoms are controlled by spatial selection of atoms and an appropriate choice of Bragg intensity. In these simulations, we found that Gaussian Bragg pulse shapes yield the smallest systematic shifts. Parasitic interferometers are suppressed by a "magic" Bragg pulse duration. The sensitivity of the apparatus was improved by the addition of AC Stark shift compensation, which permits direct experimental study of sub-part-per-billion (ppb) systematics. This upgrade allows for a 310 k momentum transfer, giving an unprecedented 6.6 Mrad measured in a Ramsey-Bordé interferometer.Atom interferometers have been used for tests of fundamental physics such as the isotropy of gravity [1], the equivalence principle [2][3][4][5], the search for dark-sector particles [6,7], and measurements of the fine structure constant α [8,9], which characterizes the strength of the electromagnetic interaction. This constant can be obtained from the electron's gyromagnetic anomaly g e − 2. At the current accuracy, this involves > 10,000 Feynman diagrams, as well as muonic and hadronic physics [10]. At increased accuracy, the tauon and the weak interaction will also be included. Since this path leads to 0.24 ppb accuracy [11], an independent measurement of α would create a unique test for the standard model. The best such measurements of α are currently based on the recoil energy 2 k 2 /2m At of an atom of mass m At that has scattered a photon of momentum k [12,13]. This measurement yields /m At , and yields α to 0.66 ppb [8] via the relationThe Rydberg constant R ∞ is known to 0.005 ppb accuracy, and the atom-to-electron mass ratio is known to better than 0.1 ppb for many species [14]. In this paper, we improve the accuracy of a measurement of the fine structure constant using Bragg diffraction, by both increasing the sensitivity of the experiment and a thorough theoretical analysis of important systematic effects. In Section I, we present an enhancement in the sensitivity of an atom interferometer (AI) by AC Stark compensation, which allows faster integration. In Section II, we investigate aberrations to the elliptical shape used for phase extraction which arise from the diffraction phase. Section III shows how this leads to phase shifts due to thermal motion, and Section IV describes how spatial filtering can be used to suppress those shifts. In Section V, we consider the influence of the Bragg pulse shape, and i...

Using an atom interferometer to measure the quotient of the reduced Planck's constant and the mass of a cesium-133 atom /m Cs , the most accurate measurement of the fine structure constant α = 1/137.035999046(27) is recorded, at an accuracy of 0.20 parts per billion (ppb). Using multiphoton interactions (Bragg diffraction and Bloch oscillations), the largest phase (12 million radians) of any Ramsey-Bordé interferometer and controlled systematic effects at a level of 0.12 ppb are demonstrated. Comparing the Penning trap measurements with the Standard Model prediction of the electron gyromagnetic anomaly a e based on the α measurement, a 2.5 σ tension is observed, rejecting dark photons as the reason for the unexplained part of the muon's gyromagnetic moment discrepancy at a 99% confidence level according to frequentist statistics. Implications for dark-sector candidates (e.g., scalar and pseudoscalar bosons, vector bosons, and axial-vector bosons) may be a sign of physics beyond the Standard Model. A future upgrade of the cesium fountain atom interferometer is also proposed to increase the accuracy of /m Cs by 1 to 2 orders of magnitude, which would help resolve the tension.

We have investigated Lorentz violation through analyzing tides-subtracted gravity data measured by superconducting gravimeters. At the level of precision of superconducting gravimeters, we have brought up and resolved an existing issue of accuracy due to unaccounted local tidal effects in previous solid-earth tidal model used. Specifically, we have taken local tides into account with a brand new first-principles tidal model with ocean tides included, as well as removed potential bias from local tides by using a worldwide array of 12 superconducting gravimeters. Compared with previous test with local gravimeters, a more accurate and competitive bound on space-space components of gravitational Lorentz violation has been achieved up to the order of 10 −10 . Einstein's equivalence principle is the foundation of general relativity. It is based on the universality of free fall, local Lorentz invariance and, local position invariance [1,2]. The universality of free fall has been tested up to accuracies of 10 −13 [3][4][5][6]. Local position invariance has been tested, e.g., by gravitational red shift measurement with atom interferometers or clocks [7,8]. In comparison, testing local Lorentz invariance (LLI) is a broad field, as violations of LLI might manifest themselves in the gravity sector itself, or in the matter sectors as well as their coupling [9,10].In the simplest case, violations of LLI in the gravity sector manifest themselves as a dependence of the force of gravity between two objects on the direction of their separation. Competitive bounds in this sector have been established by various experiments and observations [24,25], such as gravimetry [11][12][13], lunar laser ranging [14][15][16] and astrophysics observations [17,18]. Among these, local gravimetry is the one of the easy-to-access and very precise ground-based method. The underlying idea is simple: if the force of gravity is anisotropic, then the local acceleration of free fall on the rotating earth should exhibit a modulation correlated with the earth's rotation. In analyzing such tests, the influence of the sun, the moon and the planets have to be taken out, which is done by subtracting a "tidal model" describing of these influences.However, a persisting problem has been pointed out in previous works [11][12][13] whether a simple first-principles solid-earth tidal model or a more sophisticated empirical model should be used. The simple first-principles solidearth tidal model does not include any Lorentz violation signal. But it's not accurate enough beyond 10 −10 g with- * E-mail:zkhu@mail.hust.edu.cn † E-mail:hm@berkeley.edu out including local tidal effects like ocean tides. At the precision of superconducting gravimeters, it may produce fake Lorentz violating signals [13]. Sophisticated empirical models are a lot more accurate, but it's based on fitting of gravity measurement which itself may contain Lorentz-violating signals. In this work, we have reconciled the conflict with a worldwide network of gravimeters analyzed with first-principle ti...