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CERN Document Server latest documents in CERN DepartmentsenSun, 29 Nov 2015 15:56:11 GMTInvenio 1.1.3.1106-62468cds.support@cern.ch36084838125https://cds.cern.ch/img/site_logo_rss.pngCERN Document Server
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Supply of Centrifugal Water Pumps: 171
https://cds.cern.ch/record/2108349
Thu, 26 Nov 2015 13:15:36 GMThttps://cds.cern.ch/record/2108349['']Manufacturing and Supply of Transfer Line Collimators: 584
https://cds.cern.ch/record/2105096
Tue, 24 Nov 2015 10:54:09 GMThttps://cds.cern.ch/record/2105096['']Supply of Air Handling Units for Industrial HVAC Projects at CERN: 158
https://cds.cern.ch/record/2105077
Tue, 24 Nov 2015 09:39:02 GMThttps://cds.cern.ch/record/2105077['']Civil engineering works for the project “Esplanade des Particules” (Work Package 2) at CERN / Travaux de génie civil pour le projet « Esplanade des Particules » (Lot 2) au CERN: 121
https://cds.cern.ch/record/2104503
Mon, 23 Nov 2015 11:10:14 GMThttps://cds.cern.ch/record/2104503['']Physics Opportunities of a 100 TeV Proton-Proton Collider
https://cds.cern.ch/record/2104388
The discovery of the Higgs boson at the LHC exposes some of the most profound mysteries fundamental physics has encountered in decades, opening the door to the next phase of experimental exploration. More than ever, this will necessitate new machines to push us deeper into the energy frontier. In this article, we discuss the physics motivation and present the physics potential of a proton-proton collider running at an energy significantly beyond that of the LHC and a luminosity comparable to that of the LHC. 100 TeV is used as a benchmark of the center of mass energy, with integrated luminosities from 3 inverse ab to 30 inverse ab.Arkani-Hamed, NimaHan, TaoMangano, MichelangeloWang, Lian-TaoMon, 23 Nov 2015 06:45:42 GMT20 Nov 2015arXiv:1511.06495https://cds.cern.ch/record/2104388['arXiv:1511.06495']arXiv:1511.06495Supersymmetry Searches in GUT Models with Non-Universal Scalar Masses
https://cds.cern.ch/record/2104139
We study SO(10), SU(5) and flipped SU(5) GUT models with non-universal soft supersymmetry-breaking scalar masses, exploring how they are constrained by LHC supersymmetry searches and cold dark matter experiments, and how they can be probed and distinguished in future experiments. We find characteristic differences between the various GUT scenarios, particularly in the coannihilation region, which is very sensitive to changes of parameters. For example, the flipped SU(5) GUT predict the possibility of $\tilde{t}_1-\chi$ coannihilation, which is absent in the regions of the SO(10) and SU(5) GUT parameter spaces that we study. We use the relic density predictions in different models to determine upper bounds for the neutralino masses, and we find large differences between different GUT models in the sparticle spectra for the same LSP mass, leading to direct connections of distinctive possible experimental measurements with the structure of the GUT group. We find that future LHC searches for generic missing $E_T$, charginos and stops will be able to constrain the different GUT models in complementary ways, as will the Xenon 1 ton and Darwin dark matter scattering experiments and future FERMI or CTA $\gamma$-ray searches.Cannoni, MEllis, JGómez, M ELola, Sde Austri, R RuizFri, 20 Nov 2015 06:35:58 GMT19 Nov 2015arXiv:1511.06205https://cds.cern.ch/record/2104139['arXiv:1511.06205']arXiv:1511.06205Communiqué de presse du Ministère des Finances et des Comptes Publics, n. 487 du 20.10.2015
https://cds.cern.ch/record/2103999
Thu, 19 Nov 2015 13:53:53 GMTCERN-Admin-E-Guide-160https://cds.cern.ch/record/2103999Guide160Realignment of the Linac2 LEBT during the 1994/1995 machine shutdown
https://cds.cern.ch/record/2103990
Tanke, EThu, 19 Nov 2015 12:47:21 GMT8 jun 1995https://cds.cern.ch/record/2103990['']List of benefits
https://cds.cern.ch/record/2103938
List of benefits according to the rules of the CERN Health Insurance SchemeCERN, Health Insurance SchemeCERN. Geneva. HR DepartmentThu, 19 Nov 2015 08:21:47 GMT19 Nov 2015CERN-HR-Note-2015-061https://cds.cern.ch/record/21039382015061A status update on the determination of ${\Lambda}_{\overline{\rm MS}}^{N_{\rm f}=3}$ by the ALPHA collaboration
https://cds.cern.ch/record/2103860
The ALPHA collaboration aims to determine $\alpha_s(m_Z)$ with a total error below the percent level. A further step towards this goal can be taken by combining results from the recent simulations of 2+1-flavour QCD by the CLS initiative with a number of tools developed over the years: renormalized couplings in finite volume schemes, recursive finite size techniques, two-loop renormalized perturbation theory and the (improved) gradient flow on the lattice. We sketch the strategy, which involves both the standard SF coupling in the high energy regime and a gradient flow coupling at low energies. This implies the need for matching both schemes at an intermediate switching scale, $L_{\rm swi}$, which we choose roughly in the range 2-4 GeV. In this contribution we present a preliminary result for this matching procedure, and we then focus on our almost final results for the scale evolution of the SF coupling from $L_{\rm swi}$ towards the perturbative regime, where we extract the $N_{\rm f} = 3$ ${\Lambda}$-parameter, ${\Lambda}_{\overline{\rm MS}}^{N_{\rm f}=3}$, in units of $L_{\rm swi}$ . Connecting $L_{\rm swi}$ and thus the ${\Lambda}$-parameter to a hadronic scale such as $F_K$ requires 2 further ingredients: first, the connection of $L_{\rm swi}$ to $L_{\rm max}$ using a few steps with the step-scaling function of the gradient flow coupling, and, second, the continuum extrapolation of $L_{\rm max} F_K$.Brida, Mattia DallaFritzsch, PatrickKorzec, TomaszRamos, AlbertoSint, StefanSommer, RainerThu, 19 Nov 2015 07:35:26 GMT18 Nov 2015arXiv:1511.05831https://cds.cern.ch/record/2103860['arXiv:1511.05831']arXiv:1511.05831CHIS/F04 - Request for advance reimbursement
https://cds.cern.ch/record/2103346
Form for requesting advance reimbursement from the CERN Health Insurance Scheme - CHIS (UNIQA).CERN Healht Insurance Scheme, CHISCERN. Geneva. HR DepartmentTue, 17 Nov 2015 15:09:35 GMT17 Nov 2015CERN-HR-Note-2015-060https://cds.cern.ch/record/21033462015060Measurement of the space charge tune spread with a quadrupolar pick-up: New (general) formula VS. "Usual" one
https://cds.cern.ch/record/2103213
In 1966, W. Hardt derived the oscillation frequencies obtained in the presence of space charge forces and gradients errors for elliptical beams. Since then, a simple formula is usually used to relate the shift of the quadrupolar mode (obtained from the quadrupolar pick-up) and the space charge tune spread, depending only on the ratio between the two transverse equilibrium beam sizes. However, this formula is not always valid, in particular for machines running close to the coupling resonance Qx = Qy with almost round beams. A new general formula is presented, giving the space charge tune spread as a function of i) the measured shift of the quadrupolar mode, ii) the ratio between the two transverse equilibrium beam sizes and iii) the distance between the two transverse tunes.Metral, EliasTue, 17 Nov 2015 09:22:04 GMT18 Nov 2015CERN-ACC-SLIDES-2015-0001https://cds.cern.ch/record/210321320150001Fast Poisson Solvers for Self-Consistent Beam-Beam and Space-Charge Field Computation in Multiparticle Tracking Simulations
https://cds.cern.ch/record/2102532
We present two different approaches to solve the 2-dimensional electrostatic problem with open boundary conditions to be used in fast tracking codes for beam-beam and space charge simulations in high energy accelerators. We compare a fast multipoles method with a hybrid Poisson solver based on the fast Fourier transform and finite differences in polar coordinates. We show that the latter outperforms the first in terms of execution time and precision, allowing for a reduction of the noise in the tracking simulation. Furthermore the new algorithm is shown to scale linearly on parallel architectures with shared memory. We conclude by effectively replacing the HFMM by the new Poisson solver in the COMBI code.Florio, AdrienBuffat, XavierPieloni, TatianaCERN. Geneva. ATS DepartmentMon, 16 Nov 2015 13:46:39 GMT16 Nov 2015CERN-ACC-NOTE-2015-0038https://cds.cern.ch/record/210253220150038Proposal for authorisation to derogate from the standard procurement framework applicable at CERN for projects partially funded by the European Union176th Session of Council
https://cds.cern.ch/record/2102347
Mon, 16 Nov 2015 07:58:16 GMT2015-09-16https://cds.cern.ch/record/2102347['']Gauging MSSM global symmetries and SUSY breaking in de Sitter vacuum
https://cds.cern.ch/record/2102286
We elaborate on a recent study of a model of supersymmetry breaking we proposed recently, in the presence of a tunable positive cosmological constant, based on a gauged shift symmetry of a string modulus, external to the Standard Model (SM) sector. Here, we identify this symmetry with a global symmetry of the SM and work out the corresponding phenomenology. A particularly attracting possibility is to use a combination of Baryon and Lepton number that contains the known matter parity and guarantees absence of dimension-four and five operators that violate B and L.Antoniadis, IgnatiosKnoops, RobMon, 16 Nov 2015 06:29:05 GMT13 Nov 2015arXiv:1511.04283https://cds.cern.ch/record/2102286['arXiv:1511.04283']arXiv:1511.04283IR aperture measurement at β*=40 cm
https://cds.cern.ch/record/2093561
This note summarizes MD 307, performed on August 27 2015, during which we measured with beam the global apertures at 6.5 TeV with IR1 and IR5 squeezed to β* =40 cm and a half crossing angle of 205 rad. The measurement technique involved opening collimators in steps, while inducing beam losses at each step, until the main loss location moved from the collimators to the global bottleneck in one of the triplets. Measurements were performed in both beams and planes, and each measurement gave the minimum triplet aperture over IR1 and IR5. The results are in very good agreement with theoretical predictions. At the end of the MD, an asynchronous beam dump test was performed with all collimators moved in to so-called 2-σ retraction settings. This MD is one in a series meant to address various open points for the reach in β* in Run II.Bruce, RoderikGarcia Morales, HectorHermes, Pascal DominikKwee-Hinzmann, ReginaMereghetti, AlessioMirarchi, DanieleRedaelli, StefanoSalvachua Ferrando, Belen MariaSkowronski, Piotr KrzysztofValentino, GianlucaValloni, AlessandraCERN. Geneva. ATS DepartmentFri, 13 Nov 2015 10:47:21 GMT15 Sep 2015CERN-ACC-NOTE-2015-0037https://cds.cern.ch/record/209356120150037Calculation of magnetic field in a cylindrical geometry produced by sector or layer windings
https://cds.cern.ch/record/2093560
CERN. Geneva. Intersecting Storage RingsPerin, RFri, 13 Nov 2015 10:46:52 GMT15 Nov 1973CERN-ISR-MA-RP-cb-Internal-Reporthttps://cds.cern.ch/record/2093560InternalReportEffects of higher dimension operators on the Standard Model Higgs sector
https://cds.cern.ch/record/2093351
We study the effect of higher dimension operators on the electroweak finite temperature phase transition in two sectors of the Standard Model. Firstly, the Higgs-Yukawa sector, consisting of the Higgs doublet and the massive Standard Model fermions, is studied with an approximate method, Extended Mean Field Theory. Secondly, the gauge-Higgs sector, consisting of the Higgs doublet and the gauge fields of the weak interaction, is studied using Monte Carlo simulations. In both cases we find that a cutoff scale of around 1.5 TeV is needed to make the electroweak phase transition first order at the experimental value of the Higgs boson mass, which is a requirement for making electroweak baryogenesis viable.Akerlund, Oscarde Forcrand, PhilippeSteinbauer, JakobFri, 13 Nov 2015 07:12:55 GMT12 Nov 2015arXiv:1511.03867https://cds.cern.ch/record/2093351['arXiv:1511.03867']arXiv:1511.03867New Physics in $B$ decays
https://cds.cern.ch/record/2093340
While the LHC did not observe direct evidence for physics beyond the standard model, indirect hints for new physics were uncovered in the flavour sector in the decays $B\to K^*\mu^+\mu^-$, $B\to K\mu^+\mu^-/B\to Ke^+e^-$, $B_s\to\phi\mu^+\mu^-$, $B\to D^{(*)}\tau\nu$ and $h\to\tau^\pm\mu^\mp$. Each observable deviates from the SM predictions at the $2-3\,\sigma$ level only, but combining all $b\to s\mu^+\mu^-$ data via a global fit, one finds $4-5\,\sigma$ difference for NP compared to the SM and combining $B\to D^{*}\tau\nu$ with $B\to D\tau\nu$ one obtains $3.9\,\sigma$. While $B\to D^{(*)}\tau\nu$ and $h\to\tau\mu$ can be naturally explained by an extended Higgs sector, the $b\to s\mu^+\mu^-$ anomalies point at a $Z'$ gauge boson. However, it is also possible to explain $B\to D^{(*)}\tau\nu$ and $b\to s\mu^+\mu^-$ simultaneously with leptoquarks while their effect in $h\to\tau^\pm\mu^\mp$ is far too small to account for current data. Combining a 2HDM with a gauged $L_\mu-L_\tau$ symmetry allows for explaining the $b\to s\mu^+\mu^-$ anomalies in combination with $h\to\tau^\pm\mu^\mp$, predicting interesting correlations with $\tau\to3\mu$. In the light of these deviations from the SM we also discuss the possibilities of observing lepton flavour violating $B$ decays (e.g. $B\to K^{(*)}\tau^\pm\mu^\mp$ and $B_s\to\tau^\pm\mu^\mp$).Crivellin, AndreasFri, 13 Nov 2015 07:11:12 GMT12 Nov 2015arXiv:1511.04015https://cds.cern.ch/record/2093340['arXiv:1511.04015']arXiv:1511.04015Collimation with tighter TCTs at β*=40 cm
https://cds.cern.ch/record/2069154
MD 310 was carried out on August 28 2015, in order to investigate the collimation performance using nominal optics with β* =40 cm, 2 σ retraction collimator settings in IR7, and the very tight TCT settings which are necessary to protect the small normalized aperture. With these tight settings, we expect higher losses on the TCTs which should cause also higher beam-halo background at the experiments. During the MD, a total of 70 betatron loss maps were performed over a range of TCT settings and for dierent settings of the TCLAs in IR7. ATLAS and CMS were exceptionally taking data outside stable beams, in order to monitor the background. Furthermore, betatron loss maps were performed with a small momentum oset of the whole beam, induced by a shift of the RF frequency. The MD results can therefore also be used to assess the cleaning eciency in IR7 with the β* =40 cm optics, as well as the eects of energy osets on the cleaning. At the end of the MD, an asynchronous dump test was performed, in order to monitor the losses on sensitive equipment with β* =40 cm and the proposed collimator settings. This MD is one in a series meant to address various open points for the reach in β* in Run II.Bruce, RoderikHermes, Pascal DominikKwee-Hinzmann, ReginaMereghetti, AlessioMirarchi, DanieleQuaranta, ElenaRedaelli, StefanoSalvachua Ferrando, Belen MariaValentino, GianlucaValloni, AlessandraGarcia Morales, HectorCERN. Geneva. ATS DepartmentThu, 12 Nov 2015 15:47:58 GMT15 Sep 2015CERN-ACC-NOTE-2015-0036https://cds.cern.ch/record/206915420150036Design, production, testing and supply of Power Stacks: 254
https://cds.cern.ch/record/2066973
Wed, 11 Nov 2015 14:51:23 GMThttps://cds.cern.ch/record/2066973['']The history of the universe
https://cds.cern.ch/record/2066964
This book gives an accessible account of the history of the Universe; not only what happened, but why it happened. An author of textbooks on the early Universe and inflation, David Lyth now explains both cosmology and the underlying physics to the general reader. The book includes a detailed account of the almost imperceptible structure in the early Universe, and its probable origin as a quantum fluctuation during an early epoch known as the epoch of inflation. It also explains how that early structure is visible now in the cosmic microwave radiation which is our main source of information about the early Universe, and how it gave rise to galaxies and stars. The main text of the book assumes no knowledge of mathematics or physics so that it is accessible to everybody, while an appendix contains more advanced material. As a result the book will be useful for a wide spectrum of readers, including high-school students, undergraduates, postgraduates and professional physicists working in areas other than cosmology. It will also serve as “additional reading” for university courses in general astronomy, astrophysics or cosmology itself.Lyth, David HWed, 11 Nov 2015 13:29:03 GMThttps://cds.cern.ch/record/2066964['']Theta series, wall-crossing and quantum dilogarithm identities
https://cds.cern.ch/record/2066877
Motivated by mathematical structures which arise in string vacua and gauge theories with N=2 supersymmetry, we study the properties of certain generalized theta series which appear as Fourier coefficients of functions on a twisted torus. In Calabi-Yau string vacua, such theta series encode instanton corrections from $k$ Neveu-Schwarz five-branes. The theta series are determined by vector-valued wave-functions, and in this work we obtain the transformation of these wave-functions induced by Kontsevich-Soibelman symplectomorphisms. This effectively provides a quantum version of these transformations, where the quantization parameter is inversely proportional to the five-brane charge $k$. Consistency with wall-crossing implies a new five-term relation for Faddeev's quantum dilogarithm $\Phi_b$ at $b=1$, which we prove. By allowing the torus to be non-commutative, we obtain a more general five-term relation valid for arbitrary $b$ and $k$, which may be relevant for the physics of five-branes at finite chemical potential for angular momentum.Alexandrov, SergeiPioline, BorisWed, 11 Nov 2015 09:22:29 GMT09 Nov 2015arXiv:1511.02892https://cds.cern.ch/record/2066877['arXiv:1511.02892']arXiv:1511.02892$\mathcal{N}=2^\star$ from Topological Amplitudes in String Theory
https://cds.cern.ch/record/2066876
In this paper, we explicitly construct string theory backgrounds that realise the so-called $\mathcal N=2^\star$ gauge theory. We prove the consistency of our models by calculating their partition function and obtaining the correct gauge theory spectrum. We further provide arguments in favour of the universality of our construction which covers a wide class of models all of which engineer the same gauge theory. We reproduce the corresponding Nekrasov partition function once the $\Omega$-deformation is included and the appropriate field theory limit taken. This is achieved by calculating the topological amplitudes $F_g$ in the string models. In addition to heterotic and type II constructions, we also realise the mass deformation in type I theory, thus leading to a natural way of uplifting the result to the instanton sector.Florakis, IoannisAssi, Ahmad ZeinWed, 11 Nov 2015 09:22:29 GMT09 Nov 2015arXiv:1511.02887https://cds.cern.ch/record/2066876['arXiv:1511.02887']arXiv:1511.02887Jet-vetoed Higgs cross section in gluon fusion at N3LO+NNLL with small-R resummation
https://cds.cern.ch/record/2066849
We present new results for the jet-veto efficiency and zero-jet cross section in Higgs production through gluon fusion. We incorporate the N$^3$LO corrections to the total cross section, the NNLO corrections to the 1-jet rate, NNLL resummation for the jet $p_t$ and LL resummation for the jet radius dependence. Our results include known finite-mass corrections and are obtained using the jet-veto efficiency method, updated relative to earlier work to take into account what has been learnt from the new precision calculations that we include. For 13 TeV collisions and using our default choice for the renormalisation and factorisation scales, $\mu_0=m_H/2$, the matched prediction for the jet-veto efficiency increases the pure NNNLO prediction by about 2% and the two have comparable uncertainties. Relative to NNLO+NNLL results, the new prediction is 2% smaller and the uncertainty reduces from more than 10% to less than 5%. Results are also presented for the central scale $\mu_0=m_H$.Banfi, AndreaCaola, FabrizioDreyer, Frédéric AMonni, Pier FSalam, Gavin PZanderighi, GiuliaDulat, FalkoWed, 11 Nov 2015 09:20:16 GMT09 Nov 2015arXiv:1511.02886https://cds.cern.ch/record/2066849['arXiv:1511.02886']arXiv:1511.02886