3,654 research outputs found
Branching fraction and CP asymmetry of the decays B+→K0Sπ+ and B+→K0SK+
No full textAn analysis of B+ → K0
Sπ+ and B+ → K0
S K+ decays is performed with the LHCb experiment. The pp
collision data used correspond to integrated luminosities of 1 fb−1 and 2 fb−1 collected at centre-ofmass
energies of
√
s = 7 TeV and
√
s = 8 TeV, respectively. The ratio of branching fractions and the
direct CP asymmetries are measured to be B(B+ → K0
S K+
)/B(B+ → K0
Sπ+
) = 0.064 ± 0.009 (stat.) ±
0.004 (syst.), ACP(B+ → K0
Sπ+
) = −0.022 ± 0.025 (stat.) ± 0.010 (syst.) and ACP(B+ → K0
S K+
) =
−0.21 ± 0.14 (stat.) ± 0.01 (syst.). The data sample taken at
√
s = 7 TeV is used to search for
B+
c
→ K0
S K+ decays and results in the upper limit ( fc · B(B+
c
→ K0
S K+
))/( fu · B(B+ → K0
Sπ+
)) <
5.8 × 10−2 at 90% confidence level, where fc and fu denote the hadronisation fractions of a ¯b
quark
into a B+
c or a B+ meson, respectively
Measurement of the time-dependent CP asymmetry in B0 -> J/ψ KS0 decays
No full textThis Letter reports a measurement of the CP violation observables SJ/ψK0S and CJ/ψK0S in the decay channel B0→J/ψK0S performed with 1.0 fb−1 of pp collisions at s√=7 TeV collected by the LHCb experiment. The fit to the data yields SJ/ψK0S=0.73±0.07(stat)±0.04(syst) and CJ/ψK0S=0.03±0.09(stat)±0.01(syst). Both values are consistent with the current world averages and within
expectations from the Standard Model
Time Journey of Climate from the past to projected futures
No full textSea level, CO2, and temperature at different time scales. From “deep paleo” (50 to 1 million years ago) with a general cooling trend, glacial–interglacial variability covering the last 1 million years, and model scenarios for present and future climate evolution with the Earth System Model COSMOS.The slides refer to modeling results of Gierz, P., G. Lohmann, W. Wei, 2015: Response of Atlantic Overturning to Future Warming in a coupled Atmosphere-Ocean-Ice Sheet Mode. Geophysical Research Letters, 42, 6811–6818, DOI: 10.1002/2015GL065276Knorr, G., M. Butzin, A. Micheels, and G. Lohmann, 2011: A Warm Miocene Climate at Low Atmospheric CO2 levels. Geophysical Research Letters, L20701, doi:10.1029/2011GL048873 Knorr, G., and G. Lohmann, 2014: A warming climate during the Antarctic ice sheet growth at the Middle Miocene transition. Nature Geoscience, 7, 376–381. doi: 10.1038/NGEO2119Lohmann, G., M. Pfeiffer, T. Laepple, G. Leduc, and J.-H. Kim, 2013: A model-data comparison of the Holocene global sea surface temperature evolution. Clim. Past, 9, 1807-1839, doi:10.5194/cp-9-1807-2013Pfeiffer, M. and Lohmann, G., 2016: Greenland Ice Sheet influence on Last Interglacial climate: global sensitivity studies performed with an atmosphere–ocean general circulation model, Clim. Past, 12, 1313-1338. doi:10.5194/cp-12-1313-2016Stepanek, C., and G. Lohmann: Modelling mid-Pliocene climate with COSMOS. Geosci. Model Dev., 5, 1221-1243, 2012. doi:10.5194/gmd-5-1221-2012Wei, W., and G. Lohmann, 2012: Simulated Atlantic Multidecadal Oscillation during the Holocene. J. Climate, 25, 6989–7002. doi:10.1175/JCLI-D-11-00667.1 Wei, W., G. Lohmann, and M. Dima, 2012: Distinct modes of internal variability in the Global Meridional Overturning Circulation associated to the Southern Hemisphere westerly winds. J. Phys. Oceanogr., 42, 785–801. doi:10.1175/JPO-D-11-038.1Zhang, X., Lohmann, G., Knorr, G., and Xu, X., 2013: Different ocean states and transient characteristics in Last Glacial Maximum simulations and implications for deglaciation. Clim. Past, 9, 2319-2333, doi:10.5194/cp-9-2319-2013</div
Measurement of the CP-violating phase \phi s in Bs->J/\psi\pi+\pi- decays
No full textMeasurement of the mixing-induced CP-violating phase phi_s in Bs decays is of prime importance in probing new physics. Here 7421 +/- 105 signal events from the dominantly CP-odd final state J/\psi pi+ pi- are selected in 1/fb of pp collision data collected at sqrt{s} = 7 TeV with the LHCb detector. A time-dependent fit to the data yields a value of phi_s=-0.019^{+0.173+0.004}_{-0.174-0.003} rad, consistent with the Standard Model expectation. No evidence of direct CP violation is found
Predictive Association of Pre-Operative Defect Areas in the Outer Retinal Layers With Visual Acuity in Macular Hole Surgery
No full textPurpose: The purpose of this study was to develop methods to model the external limiting membrane (ELM) and ellipsoid zone (EZ) within the elevated cuff surrounding a macular hole (MH) to determine if the predicted size of the defect in these layers after virtual flattening was associated with the actual postoperative defect and best corrected visual acuity (BCVA). Methods: Patients were included who had undergone successful MH surgery. The defects in the ELM and EZ after virtual flattening were modeled using in-house software. Main outcomes were postoperative defects in ELM and EZ at 2 months and BCVA at 12 months. Results: Fifty-eight patients were included. BCVA improved from 0.87 (0.31) logMAR pre-operatively to 0.26 (0.21) at 12 months (P < 0.001). For both the ELM and EZ, the predicted virtually flattened pre-operative defects were associated with the actual postoperative defects at 2 months (R-2 = 0.33, P < 0.01 and R-2 = 0.50, P < 0.01, respectively). There was a significant association of BCVA at 12 months (adjusted R-2 = 0.85) with the pre-operative modeled area of the defect in the ELM (P < 0.01) and to a lesser extent with the defect in the EZ (P < 0.01) and base of the MH (P < 0.01). Conclusions: Virtually flattening of the pre-operative defect in the ELM provides important predictive information of visual acuity. Incorporation of tools into commercially available optical coherence tomography (OCT) devices to facilitate such measurements would provide the clinician with important prognostic information. Translational Relevance: We have developed methodology that can potentially be used to predict the postoperative state of the outer retinal layers and the associated visual outcome in patients undergoing surgery for MH
Resolution matters: Mid-Holocene atmospheric circulation
No full textThe mid-Holocene is one of the key times in the past to test models. The most prominent difference between the mid-Holocene and the present arises from the orbital configuration, which leads to an increase in summer insolation in the northern hemisphere and a decrease in the tropical and subtropical southern hemisphere in boreal winter (Lohmann et al., 2013). Several model simulations were performed to test whether the resolution of the model systems used affects the results. Special focus is put on the boreal winter atmospheric circulation in the northern hemisphere (Lohmann et al., 2021).Lohmann, G., M. Pfeiffer, T. Laepple, G. Leduc, and J.-H. Kim, 2013: A model-data comparison of the Holocene global sea surface temperature evolution. Clim. Past, 9, 1807-1839, doi: 10.5194/cp-9-1807-2013.Shi, X., and Lohmann, G., 2016: Simulated response of the mid-Holocene Atlantic Meridional Overturning Circulation in ECHAM6-FESOM/MPIOM. Journal of Geophysical Research - Oceans, doi: 10.1002/2015JC011584.Lohmann, G., A. Wagner, M. Prange, 2021: Resolution of the atmospheric model matters for the Northern Hemisphere Mid-Holocene climate. Dynamics of Atmospheres and Oceans, 93, 101206 doi:10.1016/j.dynatmoce.2021.101206</div
A study of CP violation in B±→DK±B±→DK± and B±→Dπ±B±→Dπ± decays with D→KS0K±π∓ final states
No full textA first study of CP violation in the decay modes B± → [K0S K ±π∓]Dh± and B± → [K0S K ∓π±]Dh±, where h labels a K or π meson and D labels a D0 or D0 meson, is performed. The analysis uses the LHCb data set collected in pp collisions, corresponding to an integrated luminosity of 3 fb−1. The analysis is sensitive to the CP-violating CKM phase γ through seven observables: one charge asymmetry in each of the four modes and three ratios of the charge-integrated yields. The results are consistent with measurements of γ using other decay modes
Lessons from the Past
No full textThis is a talk in 2022 based on several ideas and papers.
Lohmann, G., M. Pfeiffer, T. Laepple, G. Leduc, and J.-H. Kim, 2013: A model-data comparison of the Holocene global sea surface temperature evolution. Clim. Past, 9, 1807-1839, doi:10.5194/cp-9-1807-2013
Lohmann, G., 2018: ESD Ideas: The stochastic climate model shows that underestimated Holocene trends and variability represent two sides of the same coin. Earth Syst. Dynam. 9, 1279-1281. doi:10.5194/esd-9-1279-2018
Lohmann, G., M. Butzin, N. Eissner, X. Shi, C. Stepanek, 2020: Abrupt climate and weather changes across timescales. Paleoceanography and Paleoclimatology 35 (9), e2019PA003782, DOI:10.1029/2019PA003782
Lohmann, G.: Temperatures from energy balance models: the effective heat capacity matters, Earth Syst. Dynam., 11, 1195–1208, https://doi.org/10.5194/esd-11-1195-2020, 2020.
Lohmann, G., G. Knorr, A. Hossain, C. Stepanek, 2022: Effects of CO2 and Ocean Mixing on Miocene and Pliocene Temperature Gradients. Paleoceanography and Paleoclimatology 37, (2), e2020PA003953, doi:10.1029/2020PA003953</p
Study of the Higgs-boson CP properties in the ττ decay channel with the CMS experiment
No full textThe CP violation is an interesting phenomenon, being part of the Sakharov conditions to explain the baryogenesis. So far CP-violating processes were found only in the quark sector induced by the complex phase in the Cabibbo-Kobayashi-Maskawa matrix. These do not provide the amount of CP violation necessary to generate the matter-antimatter asymmetry in the observed universe. For this reason scientists are searching for new sources of CP violation. This work focuses on the Higgs sector: the strategies proposed by theorists for measuring CP-violating Yukawa couplings in Higgs-boson decays to tau leptons are studied with simulated and data samples. Data consist of proton-proton collisions at a center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 35.9 , collected with the CMS detector in the 2016 data-taking period. The reconstruction of the CP-sensitive observable is described, with particular emphasis on the proper treatment of the primary event vertex and the performance for the measurement of the so-called impact parameter of tracks originating from tau-lepton decays. An estimation of the actual sensitivity to detect CP-violating couplings of the Higgs boson in 2016 data is performed and prospects for improvements are discussed
Paleoclimate dynamics: Questions and Applications with FESOM and AWI-ESM
No full textQuestions and Applications with FESOM and AWI-ESM
related papers:
Ackermann, L., C. Danek, P. Gierz, and G. Lohmann, 2020: AMOC recovery in a multi-centennial scenario using a coupled atmosphere-ocean-ice sheet model. Geophysical Research Letters, 47 (16), e2019GL086810, DOI:10.1029/2019GL086810
Lohmann, G., M. Butzin, N. Eissner, X. Shi, C. Stepanek, 2020: Abrupt climate and weather changes across timescales. Paleoceanography and Paleoclimatology 35 (9), e2019PA003782, DOI:10.1029/2019PA003782, Special Section AGU Grand Challenges in the Earth and Space Sciences.
Brierley, C. M., Zhao, A., Harrison, S. P., Braconnot, P., Williams, C. J. R., Thornalley, D. J. R., Shi, X., Peterschmitt, J.-Y., Ohgaito, R., Kaufman, D. S., Kageyama, M., Hargreaves, J. C., Erb, M. P., Emile-Geay, J., D'Agostino, R., Chandan, D., Carré, M., Bartlein, P. J., Zheng, W., Zhang, Z., Zhang, Q., Yang, H., Volodin, E. M., Tomas, R. A., Routson, C., Peltier, W. R., Otto-Bliesner, B., Morozova, P. A., McKay, N. P., Lohmann, G., Legrande, A. N., Guo, C., Cao, J., Brady, E., Annan, J. D., and Abe-Ouchi, A.: Large-scale features and evaluation of the PMIP4-CMIP6 midHolocene simulations, Clim. Past, 16, 1847–1872, doi:10.5194/cp-16-1847-2020, 2020.
Gowan, E.J., X. Zhang, S. Khosravi, A. Rovere, P. Stocchi, A. L. C. Hughes, R. Gyllencreutz, J. Mangerud, J. I. Svendsen, G. Lohmann, 2021: A new global ice sheet reconstruction for the past 80,000 years. Nature comm. 12, 1199 https://doi.org/10.1038/s41467-021-21469-w.
Niu, L., G. Lohmann, P. Gierz, E. J. Gowan, G. Knorr, 2021: Coupled climate-ice sheet modelling of MIS-13 reveals a sensitive Cordilleran Ice Sheet. Global and Planetary Change, 103474, doi:10.1016/j.gloplacha.2021.103474
Hinck, S., Gowan, E. J., Zhang, X., and Lohmann, G.: PISM-LakeCC: Implementing an adaptive proglacial lake boundary in an ice sheet model, The Cryosphere, 16, 941–965, https://doi.org/10.5194/tc-16-941-2022, 2022.
Sutter, J., P. Gierz, K. Grosfeld, M. Thoma, and G. Lohmann, 2016: Ocean temperature thresholds for Last Interglacial West Antarctic Ice Sheet collapse. Geophysical Research Letters, 43 (6), 2675–2682. doi: 10.1002/2016GL067818
Lohmann, G., L. Lembke-Jene, R. Tiedemann, X. Gong, P. Scholz, J. Zou, X. Shi, 2019: Challenges in the Paleoclimatic Evolution of the Arctic and Subarctic Pacific since the Last Glacial Period — the Sino-German Pacific – Arctic Experiment (SiGePAX). Challenges 10(1), 13; doi: 10.3390/challe10010013
Danek, C., P. Scholz, and G. Lohmann, 2019: Effects of high resolution and spinup time on modeled North Atlantic circulation. J. Physical Oceanography, 49 (5), 1159–1181. doi:10.1175/JPO-D-18-0141.1.
Scholz,P., G. Lohmann, Q. Wang, S. Danilov, 2013: Evaluation of a Finite-Element Sea-Ice Ocean Model (FESOM) set-up to study the interannual to decadal variability in the deep-water formation rates. Ocean Dynamics 63 (4), 347-370. </p
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