Complete classification of 1D gapped quantum phases in interacting spin systems

Quantum phases with different orders exist with or without breaking the symmetry of the system. Recently, a classification of gapped quantum phases which do not break time reversal, parity or on-site unitary symmetry has been given for 1D spin systems in [X. Chen, Z.-C. Gu, and X.-G. Wen, Phys. Rev. B \textbf{83}, 035107 (2011); arXiv:1008.3745]. It was found that, such symmetry protected topological (SPT) phases are labeled by the projective representations of the symmetry group which can be viewed as a symmetry fractionalization. In this paper, we extend the classification of 1D gapped phases by considering SPT phases with combined time reversal, parity, and/or on-site unitary symmetries and also the possibility of symmetry breaking. We clarify how symmetry fractionalizes with combined symmetries and also how symmetry fractionalization coexists with symmetry breaking. In this way, we obtain a complete classification of gapped quantum phases in 1D spin systems. We find that in general, symmetry fractionalization, symmetry breaking and long range entanglement(present in 2 or higher dimensions) represent three main mechanisms to generate a very rich set of gapped quantum phases. As an application of our classification, we study the possible SPT phases in 1D fermionic systems, which can be mapped to spin systems by Jordan-Wigner transformation.Comment: 15 pages, 3 figure

The Universal Real Projective Plane: LHC phenomenology at one Loop

The Real Projective Plane is the lowest dimensional orbifold which, when combined with the usual Minkowski space-time, gives rise to a unique model in six flat dimensions possessing an exact Kaluza Klein (KK) parity as a relic symmetry of the broken six dimensional Lorentz group. As a consequence of this property, any model formulated on this background will include a stable Dark Matter candidate. Loop corrections play a crucial role because they remove mass degeneracy in the tiers of KK modes and induce new couplings which mediate decays. We study the full one loop structure of the corrections by means of counter-terms localised on the two singular points. As an application, the phenomenology of the (2,0) and (0,2) tiers is discussed at the LHC. We identify promising signatures with single and di-lepton, top antitop and 4 tops: in the dilepton channel, present data from CMS and ATLAS may already exclude KK masses up to 250 GeV, while by next year they may cover the whole mass range preferred by WMAP data.Comment: 45 pages, 3 figure

Molecular Fountain

The resolution of any spectroscopic or interferometric experiment is ultimately limited by the total time a particle is interrogated. We here demonstrate the first molecular fountain, a development which permits hitherto unattainably long interrogation times with molecules. In our experiments, ammonia molecules are decelerated and cooled using electric fields, launched upwards with a velocity between 1.4 and 1.9\,m/s and observed as they fall back under gravity. A combination of quadrupole lenses and bunching elements is used to shape the beam such that it has a large position spread and a small velocity spread (corresponding to a transverse temperature of $<$10\,$\mu$K and a longitudinal temperature of $<$1\,$\mu$K) when the molecules are in free fall, while being strongly focused at the detection region. The molecules are in free fall for up to 266\,milliseconds, making it possible to perform sub-Hz measurements in molecular systems and paving the way for stringent tests of fundamental physics theories

Functional genomics screen identifies YAP1 as a key determinant to enhance treatment sensitivity in lung cancer cells

Survival for lung cancer patients remains dismal and is largely attributed to treatment resistance. To identify novel target genes the modulation of which could modify platinum resistance, we performed a high-throughput RNAi screen and identified Yes-associated protein (YAP1), a transcription coactivator and a known oncogene, as a potential actionable candidate. YAP1 ablation significantly improved sensitivities not only to cisplatin but also to ionizing radiation, both of which are DNA-damaging interventions, in non-small cell lung cancer (NSCLC) cells. Overall YAP1 was expressed in 75% of NSCLC specimens, whereas nuclear YAP1 which is the active form was present in 45% of 124 resected NSCLC. Interestingly, EGFR-mutated or KRAS-mutated NSCLC were associated with higher nuclear YAP1 staining in comparison to EGFR/KRAS wild-type. Relevantly, YAP1 downregulation improved sensitivity to erlotinib, an EGFR inhibitor. A pharmacological inhibitor of YAP1 signaling, verteporfin also synergized with cisplatin, radiation and erlotinib in NSCLC cells by potentiating cisplatin and radiation-related double-stranded breaks and decreasing expression of YAP1 and EGFR. Taken together, our study is the first to indicate the potential role of YAP1 as a common modulator of resistance mechanisms and a potential novel, actionable target that can improve responses to platinum, radiation and EGFR-targeted therapy in lung cancer

Natural Little Hierarchy from a Partially Goldstone Twin Higgs

We construct a simple theory in which the fine-tuning of the standard model is significantly reduced. Radiative corrections to the quadratic part of the scalar potential are constrained to be symmetric under a global U(4) x U(4)' symmetry due to a discrete Z_2 "twin" parity, while the quartic part does not possess this symmetry. As a consequence, when the global symmetry is broken the Higgs fields emerge as light pseudo-Goldstone bosons, but with sizable quartic self-interactions. This structure allows the cutoff scale, \Lambda, to be raised to the multi-TeV region without significant fine-tuning. In the minimal version of the theory, the amount of fine-tuning is about 15% for \Lambda = 5 TeV, while it is about 30% in an extended model. This provides a solution to the little hierarchy problem. In the minimal model, the "visible" particle content is exactly that of the two Higgs doublet standard model, while the extended model also contains extra vector-like fermions with masses ~(1-2)TeV. At the LHC, our minimal model may appear exactly as the two Higgs doublet standard model, and new physics responsible for cutting off the divergences of the Higgs mass-squared parameter may not be discovered. Several possible processes that may be used to discriminate our model from the simple two Higgs doublet model are discussed for the LHC and for a linear collider.Comment: 22 page

Stop the Top Background of the Stop Search

The main background for the supersymmetric stop direct production search comes from Standard Model ttbar events. For the single-lepton search channel, we introduce a few kinematic variables to further suppress this background by focusing on its dileptonic and semileptonic topologies. All are defined to have end points in the background, but not signal distributions. They can substantially improve the stop signal significance and mass reach when combined with traditional kinematic variables such as the total missing transverse energy. Among them, our variable M^W_T2 has the best overall performance because it uses all available kinematic information, including the on-shell mass of both W's. We see 20%-30% improvement on the discovery significance and estimate that the 8 TeV LHC run with 20 fb-1 of data would be able to reach an exclusion limit of 650-700 GeV for direct stop production, as long as the stop decays dominantly to the top quark and a light stable neutralino. Most of the mass range required for the supersymmetric solution of the naturalness problem in the standard scenario can be covered.Comment: 16 pages, 5 figure

Insertion Magnets

Chapter 3 in High-Luminosity Large Hadron Collider (HL-LHC) : Preliminary Design Report. The Large Hadron Collider (LHC) is one of the largest scientific instruments ever built. Since opening up a new energy frontier for exploration in 2010, it has gathered a global user community of about 7,000 scientists working in fundamental particle physics and the physics of hadronic matter at extreme temperature and density. To sustain and extend its discovery potential, the LHC will need a major upgrade in the 2020s. This will increase its luminosity (rate of collisions) by a factor of five beyond the original design value and the integrated luminosity (total collisions created) by a factor ten. The LHC is already a highly complex and exquisitely optimised machine so this upgrade must be carefully conceived and will require about ten years to implement. The new configuration, known as High Luminosity LHC (HL-LHC), will rely on a number of key innovations that push accelerator technology beyond its present limits. Among these are cutting-edge 11-12 tesla superconducting magnets, compact superconducting cavities for beam rotation with ultra-precise phase control, new technology and physical processes for beam collimation and 300 metre-long high-power superconducting links with negligible energy dissipation. The present document describes the technologies and components that will be used to realise the project and is intended to serve as the basis for the detailed engineering design of HL-LHC.Comment: 19 pages, Chapter 3 in High-Luminosity Large Hadron Collider (HL-LHC) : Preliminary Design Repor

New speleothem data from Molinos and Ejulve caves reveal Holocene hydrological variability in northeast Iberia

New speleothem records from northeastern Iberian caves provide data to explore the climatic patterns during the Holocene. We present delta C-13 and Mg/Ca from three speleothems from two different caves located in the Iberian Range allowing replication of the climatic signal for several millennia. Through the integration of those stalagmites covering since the Holocene onset to 2 ka, the early Holocene (11.7-8.5 ka) appears as the wettest interval. A marked change towards aridity is observed during the middle Holocene (8.5-4.8 ka) and an increase of humidity afterwards (4.8-2 ka). This three-part pattern, contrasting with other Iberian sequences, seems to be associated with the different role that seasonality has played in the response of different proxies (or records) to changes in water availability. Interpreting our speleothem records as changes in winter-spring precipitation along the Holocene allows reconciling previous data on hydrological variability from the western Mediterranean borderlands

Waiting for Precise Measurements of K^+->pi^+ nu nu and K_L->pi^0 nu nu

In view of future plans for accurate measurements of the theoretically clean branching ratios Br(K+ -> pi+ nu nu) and Br(KL -> pi0 nu nu), that should take place in the next decade, we collect the relevant formulae for quantities of interest and analyze their theoretical and parametric uncertainties. We point out that in addition to the angle beta in the unitarity triangle (UT) also the angle gamma can in principle be determined from these decays with respectable precision and emphasize in this context the importance of the recent NNLO QCD calculation of the charm contribution to K+ -> pi+ nu nu and of the improved estimate of the long distance contribution by means of chiral perturbation theory. In addition to known expressions we present several new ones that should allow transparent tests of the Standard Model (SM) and of its extensions. While our presentation is centered around the SM, we also discuss models with minimal flavour violation and scenarios with new complex phases in decay amplitudes and meson mixing. We give a brief review of existing results within specific extensions of the SM, in particular the Littlest Higgs Model with T-parity, Z' models, the MSSM and a model with one universal extra dimension. We derive a new "golden" relation between B and K systems that involves (beta,gamma) and Br(KL -> pi0 nu nu) and investigate the virtues of (R_t,beta), (R_b,gamma), (beta,gamma) and (etabar,gamma) strategies for the UT in the context of K -> pi nu nu decays with the goal of testing the SM and its extensions.Comment: 56 pages, 18 figures, Section on Long Distance Contributions, 2 Figures and few References added, Uses Rev Mod Phys Style; Includes new results of NNLO calculation as well as matrix elements, extended and modified sections on new physic

Mechanical Design Analysis of MQXFB, the 7.2-m-Long Low-β Quadrupole for the High-Luminosity LHC Upgrade

As part of the High-Luminosity Large Hadron Collider (LHC) Project, a set of Nb Snquadrupoles are being developed, aiming to enhance the performance of the inner triplets. The new magnets, identified as MQXFA and MQXFB, will share the same cross section with two different lengths, 4.2 and 7.2 m, respectively. During the magnet development, three short models were tested, along with a number of mechanical models, demonstrating the capability of the magnet cross section to achieve the specified performances. The same performances are now required for the full-length magnets. To ensure this, the authors studied the impact of the magnet length on the capability of the structure to provide an adequate support to the coils. Finite element and simplified analytical models were used to evaluate the impact of the magnet length on the stresses in the magnet ends and coil elongation during powering. The models were calibrated using the results from the short model tests, and used to provide an indication on the required prestress and its foreseen impact on the magnet performance.