CERN Joint EP/PP & LPCC/EP/PP Seminar

Michelangelo Mangano, Maria Spiropulu, Guillaume Unal
organized by

Main Auditorium, Council Chamber, 60-6-015 or 222-R-001

Tuesday (if needed, also Monday) 11:00-12:00, tea & coffee at 10:30 unless otherwise indicated

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2010 Seminars

Michael J. Morello (INFN/Pisa)
Measurement of CP violation in the D0 → π+π- at CDF
November 30, 2010

I present a measurement of the CP violating asymmetry in D0 → π+π- decays using approximately 215,000 decays reconstructed in about 5.94 fb-1 of CDF data. We use the strong D*+ → D0 π+ decay ("D* tag") to identify the flavor of the charmed meson at production time and exploit CP-conserving strong c c-bar pair-production in p p-bar collisions. Higher statistic samples of Cabibbo-favored D0 →K- π+ decays with and without D*tag are used to highly suppress systematic uncertainties due to detector effects. The result, at the per mil level, is the world's most precise measurement to date.


Biagio Di Micco (CERN/Universita degli Studi di Roma Tre)
Study of Phi meson radiative decays at Kloe, η/η' mixing angle and η' gluonium content
September 28, 2010

Radiative Phi decays to scalars a_0, f_0, sigma and to pseudoscalars η and η' have been studied by the KLOE experiment at the DAFNE Phi factory. The decays of scalars to pi pi and eta pi have been analyzed according different theoretical models to infer information on their internal structure (q-qbar or four-quark states, or KK molecules). Precise measurements of the radiative Phi decays to eta and eta' allow to estimate the η/η' mixing angle. The impact of these measurements on the issue of the gluonium fraction inside the etaprime is discussed..


N.B. This is a special LPCC/EP/PP seminar held at the Main Auditorium at 5:00 pm
Guido Tonelli (Universita' di Pisa, INFN, CERN) , Gunther Roland (Massachusetts Institute of Technology (MIT))
Long-Range Near-Side Angular Correlations in Proton-Proton Interactions in CMS
September 21, 2010

Results on two-particle angular correlations for charged particles emitted in proton-proton collisions at center of mass energies of 0.9, 2.36 and 7 TeV over a broad range of pseudorapidity (η) and azimuthal angle (φ) are presented using data collected with the CMS detector at the LHC. Short-range correlations in Δη, which are studied in minimum bias events, are characterized using a simple independent cluster parameterization in order to quantify their strength (cluster size) and their extent in η (cluster decay width). Long-range azimuthal correlations are studied more differentially as a function of charged particle multiplicity and particle transverse momentum using a 980 nb-1 data set at 7 TeV. In high multiplicity events, a pronounced structure emerges in the two-dimensional correlation function for particles in intermediate pT’s of 1-3 GeV/c, 2.0< |Δη|<4.8 and Δφ≈0. This is the first observation of such a ridge-like feature in two-particle correlation functions in pp or p-pbar collisions

Slides, live webcast, video recording

Michal Kreps (University of Warwick)
Measurement of CP Violation in Bs → J/ψ φ Decays at CDF
September 21, 2010

The B0s mixing phase βs is a key probe of physics beyond the standard model (SM). The first Tevatron measurements hinted at a ~2σ departure from the SM expectations. We present a new analysis using B0s → J/ψ φ decays reconstructed in 5.2 fb-1 of data collected by CDF detector, where tightened bounds on the mixing phase are obtained along with an improved measurement of the decay-width difference ΔΓs and of B0s.


Alexey Zhemchugov (Joint Inst. for Nuclear Research (JINR))
Recent results from HARP-CDP and the "LSND anomaly"
September 14, 2010

The HARP-CDP group analyzed hadroproduction data recorded by the HARP detector at the CERN-PS. Objects of study are (i) double-differential inclusive cross-sections of proton and pion production on nuclei ranging from beryllium to lead that permit, inter alia, interesting comparisons between nuclei with different atomic number; and (ii) comparisons of the data with predictions of the FLUKA and the Geant4 programs. A further focus of interest is pion production by a 1.5 GeV/c proton beam, with a view to cross-checking the calculation of the electron-antineutrino background in the LSND experiment. Until now, a 3.8 sigma excess of electron-antineutrinos, claimed by LSND and known as "LSND anomaly", has been interpreted as evidence of muon-antineutrino to electron-antineutrino oscillations which in turn has led to the suggestion of "sterile" neutrinos. We report on an independent calculation of LSND's electron-antineutrino background, using HARP-CDP data, and taking into account pion production by neutrons which had been ignored in LSND's calculations. LSND's claim of a 3.8 sigma excess cannot be upheld.


Aldo Antognini (Max Planck Institute for Quantum Optics, Garching, Germany / ETH, Zurich, Switzerland)
The Proton Radius Puzzle
August 10, 2010

At the Paul Scherrer Institute, Switzerland, we have recently measured the 2S − 2P transition frequency (Lamb shift) in muonic hydrogen (μp) with 20 ppm precision by means of laser spectroscopy. From this measurement we have determined the rms charge radius of the proton. The new proton radius value rp = 084184(67)fm is 10 times more precise than previously obtained. However, it disagrees by 5 standard deviations from the current CODATA value and 3 standard deviations from e-p scattering results. The origin of this discrepancy is not yet known. It may come from theory of the muonic hydrogen energy levels (used to deduce the new value), or from problems in hydrogen spectroscopy experiments or hydrogen energy level theory (both used to deduce the CODATA value), or from new physics. Experimental setup, measurements and results will be presented. Additionally the key issues regarding the observed discrepancy will be discussed. The discrepancy simply raises new questions in the muonic sector, in bound-state QED and around the proton, holding the potential for new insights.


Geoff Mills (LANL)
New Observations by the MiniBooNE Experiment
July 28, 2010

The MiniBooNE neutrino oscillation search experiment at Fermilab has recently completed the analysis of anti-neutrino data it has collected in Fermilab's booster neutrino beam. With 5.66x10**20 protons on target in anti-neutrino mode the experiment is now becoming sensitive the the excess numubar-nuebar signal observed by LSND. This presentation will discuss the MiniBooNE data, its interpretation, and its implications to the neutrino community.


William Wester (Fermilab)
Laser experiments at Fermilab to search for exotic particles and new properties of space time
July 12, 2010

he GammeV laser experiments will be described which have already produced results for a search for low mass axion-like scalar and pseudoscalar particles. A modification of the design of the apparatus has allowed for a search for a chameleon particle - a possible particle candidate for dark energy. New results from GammeV-CHASE, a new dedicated CHameleon Afterglow Search Experiment, will be presented. Future work at Fermilab in this area includes R&D towards a much more sensitive axion-like particle search as well as a new initiative to test for the holographic nature of space time.


Sabine Lammers (Indiana University)
Recent QCD results from D0
June 22, 2010

A precise understanding of jets at the D0 Experiment in RunII of the Tevatron has allowed for a plethora of measurements that tests perturbative QCD in several different ways. I will review recent cross section measurements of jets and vector boson + jets final states. These processes make up the overwhelming backgrounds to many New Physics searches. They are therefore critical backgrounds to measure precisely in order to make discoveries at the Tevatron or LHC.


Bruce Hoeneisen (University San Francisco of Quito)
Evidence for an anomalous like-sign dimuon charge asymmetry
June 14, 2010

We measure the charge asymmetry A of like-sign dimuon events in 6.1 fb-1 of pp collisions recorded with the D0 detector at a center-of-mass energy √s = 1.96 TeV at the Fermilab Tevatron collider. From A, we extract the like-sign dimuon charge asymmetry in semileptonic b-hadron decays: Absl = -0.00957 ± 0.00251 (stat) ± 0.00146 (syst). This result differs by 3.2 standard deviations from the standard model prediction Absl(SM) = (-2.3+0.5 -0.6) x 10-4 and provides first evidence of anomalous CP-violation in the mixing of neutral B mesons.


Kenneth Lane (Boston University)
Low-Scale Technicolor at the LHC
June 8, 2010

Technicolor, the natural explanation of electroweak symmetry breaking, requires extended technicolor (ETC) to give masses to quarks, leptons and technipions (πT). Suppressing flavor-changing neutral current interactions induced by ETC to an acceptable level requires, in turn, that the TC gauge coupling αTC runs very slowly, or “walk”. Two important phenomenological consequences arise from walking technicolor: (1) The characteristic energy scale ΛTC is likely to be quite low, with the lightest techni-vector mesons ρT , ωT , αT as light as several 100 GeV. (2) Walking technicolor enhances technipion masses so much that the light techni-vectors’ all-πT decay modes are closed,making them very narrow and with spectacular decay modes. I will present simulations of the ρT , ωT , αT discovery channels at the LHC and of the reach of the early LHC for them. There is no doubt that, at design energy and luminosity, the LHC can rule out – or discover – low-scale technicolor. Slides

Vassili Perepelitsa (Instituto de Fisica Corpuscular (IFIC) UV-CSIC and ITEP (Moscow))
Anomalous soft photon production in multiple hadron processes
May 17, 2010

Electromagnetic radiation in the soft photon region arising from interacting hadrons is considered to be well understood theoretically: the inner hadronic bremsstrahlung is expected to be the dominant source of the direct soft photons in these processes. However several CERN experiments (WA27, NA22, WA83, WA91, WA102 and DELPHI)observed soft photon signals exceeding predicted hadronic bremsstrahlung rates by several times. In spite of being under active investigation, the effects still lack a theoretical explanation. A collection of experimental results will be presented in this talk, as a challenge to theoreticians, with emphasis on the recent DELPHI observations. Slides

Pietro Faccioli (LIP/IST)
Understanding quarkonium polarization
May 3, 2010

Quarkonium polarization is presently not understood. Part of this puzzling situation is caused by the fact that most experiments only present a fraction of the information derivable from the data: only one polarization frame and only the polar projection of the decay angular distribution. Such incomplete results prevent model-independent physical conclusions. We show that the polarization measurement must be approached as an intrinsically multidimensional problem. We also propose a frame-invariant formalism that minimizes the dependence of the measurement on the experimental acceptance, facilitating the comparison with theory and providing some control over systematic biases that might be caused by the limitations of the detectors. We show that rotational properties of angular momentum imply the existence of a frame-invariant relation which applies to the dilepton decay distribution of any J=1 state, even in the presence of parity-violating effects (relevant to decays of gauge bosons), and which can be formally seen as a generalization of the (Drell-Yan specific) Lam-Tung identity. Slides

Hideki Miyake (University of Tsukuba)
Results on B Physics at CDF
April 27, 2010

In order to pursue new physics beyond the Standard Model (SM), approaches from flavor sector play an important role since they are complementary to direct searches for BSM processes like Supersymetry (SUSY) particle production. At a center-of-mass energy of 1.96 TeV the Tevatron proton-antiproton collider provides a large amount of b quarks by pair production and generates all sorts of b hadrons. Various B physics analyses are ongoing at CDF with the rich yield of b hadrons collected by the CDF II detector. We present recent CDF B physics results, including the forward-backward asymmetry measurement in B→K(*) μ+μ-, measurement of the polarization amplitudes of Bs→φ φ, and the CDF/D0 combined measurement of the Bs mixing phase using 2.8/fb data per experiment. Slides

Teresa Marrodan Undagoitia (University Zurich)
Direct dark matter search with the XENON100 experiment
April 19, 2010

During the last years, liquid noble gases have proven a great potential as detector medium for dark matter searchs. Among them, xenon has the advantage of combining a high WIMP(Weakly Interacting Massive Particle)sensitivity with an excellent self-shielding capability for background reduction. A common technique, which has been demonstrated, e.g. by the XENON10 experiment, is to employ a two-phase TP(Time Projection Chamber), where the produced light and charge is detected by PMTs. XENON100 is a 65kg active volume detector placed at the Gran Sasso underground laboratory in Italy. Currently, the detector is taking dark matter data. Due to its low-radioactivity materials (designed for 10mDRU)and its large mass, it would be able to reach a sensitivity for the WIMP-nucleus cross section of 2x10-45cm2 at 100 GeV WIMP mass. After a short introduction to dark matter and its detection possibilities,the XENON100 detector, its calibration and characterization will be explained. The status and first results of the XENON100 experiment will be presented as well. Slides

Anna Holin (University College London)
New results for muon neutrino to electron neutrino oscillations in the MINOS experiment
April 12, 2010

MINOS is a long-baseline neutrino oscillation experiment situated along Fermilab's high-intensity NuMI neutrino beam. MINOS has completed an updated search for muon neutrino to electron neutrino transitions, observation of which would indicate a non-zero value for the neutrino mixing angle θ13. The present 7x1020 protons-on-target data set represents more than double the exposure used in the previous analysis. The new result and its implications are presented. Slides

Graziano Venanzoni (INFN)
KLOE measurement of the σ(e+ e- → π+ π -(γ)) with initial state radiation and the ππ contribution to the muon anomaly
March 23, 2010

The KLOE experiment at the φ factory DAΦNE in Frascati (near Rome) is the first to have employed Initial State Radiation (ISR) to precisely determine the e+ e- → π+ π -(γ) cross section below 1 GeV. Two different configurations have been investigated: (a) a non-observed photon, emitted at small angle (SA), whose energy is obtained by kinematics; (b) a photon emitted at large angle and detected in the calorimeter (LA) where its energy is measured. With the two samples the M2ππ range 0.1 < M2ππ < 0.95 GeV2 is covered. KLOE has recently published a measurement of the ππ cross section at SA, and presented a new independent measurement at LA using data taken in 2006 at a collision energy of 1 GeV, 20 MeV below the φ-peak. We present past results and discuss future prospects of these measurements as well as their impact on the evaluation of the hadronic contribution to the muon anomaly. Slides

N.B. This is a special EP/PP/LPCC seminar held at the Main Auditorium at 4:30 pm
Jan Fiete Grosse-Oetringhaus (CERN)
Charged-particle multiplicity at LHC energies
March 22, 2010

The talk presents the measurement of the pseudorapidity density and the multiplicity distribution with ALICE at the achieved LHC energies of 0.9 and 2.36 TeV. An overview about multiplicity measurements prior to LHC is given and the related theoretical concepts are briefly discussed. The analysis procedure is presented and the systematic uncertainties are detailed. The applied acceptance corrections and the treatment of diffraction are discussed. The results are compared with model predictions. The validity of KNO scaling in restricted phase space regions is revisited. Slides
2009 Seminars

Prisca Cushman (University of Minnesota)
Results from the final 5-tower run of CDMS
Dec 18, 2009

I will present new results from the recent blind analysis of 612 kg-days of raw exposure using the CDMS germanium detectors at Soudan. CDMS uses ionization and athermal phonon signals to discriminate between candidate (nuclear recoil) and background (electron recoil) events in Ge crystals cooled to ~ 50 mK. Timing, yield, and position information allows us to tune our expected background leakage into the signal region to less than one event. I will report on what we saw when we "opened the box", whether we have seen WIMPs or not, and implications for future dark matter direct detection experiments. Slides
Alberica Toia (CERN)
Electromagnetic Radiation from a Quark Gluon Plasma
Dec 15, 2009

PHENIX has measured an enhanced production of e+e- pairs In the low mass region, below the phi meson, in Au+Au collisions at sqrt(s_NN)=200GeV. At low mass and high p_T the mass shape of the excess is used to deduce the invariant yield of real direct photons. In central Au+Au the excess of direct photons above the photon yield in p+p is exponential with an inverse slope of T = 221 +/- 19(stat) +/- 19(syst) MeV, higher than the one predicted by lattice QCD for a phase transition. At low mass and low p_T the Au+Au spectrum shows a further significant enhancement, under-predicted by theoretical models, that increases with centrality and has an inverse slope of T~100 MeV, lower than that of hadrons with similar mass and similar to the freeze-out temperature. [arXiv:0912.0244] Slides
Milind Diwan (Brookhaven National Laboratory)
Recent Results from FNAL long baseline program and future plans
Dec 14, 2009

I will describe the currently running MINOS experiment at FNAL and the future plans for the accelerator based neutrino oscillation program including NOvA and the Homestake based initiative. I will describe the recent data and analysis from the MINOS experiment with emphasis on the electron neutrino result. I will conclude with plans for the experiment with a super neutrino beam from Fermilab to the underground laboratory at the Homestake mine. Slides
Krisztian Peters (University of Manchester)
Higgs Searches -- Latest Results from the Tevatron
Dec 1, 2009

The current status of Standard Model Higgs searches at the Tevatron is presented. A comprehensive program of searches in many Higgs boson production and decay channels is underway, with recent results using up to 5.4/fb of data collected with the CDF and D0 detectors. The major contributing processes include associated production (WH → lνbb, ZH → ννbb, ZH → llbb) and gluon fusion (gg → H → WW). Improvements across the full accessible mass range resulting from the larger data sets, improved analyses techniques and increased signal acceptance will be discussed. A new CDF and D0 combined result with the updated data set will also be presented. Finally, I will discuss prospects for Higgs searches at the Tevatron. Slides
Alvaro De Rújula (IFT(CSIC/UAM), CIEMAT, BU, CERN)
A Higgs-Analysis Vade Mecum
Nov 2, 2009

The properties of the elusive scalar of the standard model, given its mass, are entirely specified. In spite of this, there are good reasons to re-discuss some obvious questions:
  • To what extent does a given set of observations compatible with the predictions constitute an indisputable discovery?
  • What process and analysis procedure can reach 'discovery level' first?
  • With what confidence can one determine the quantum numbers of a putative scalar, and study whether it is elementary or composite, and pure or 'impure' in its couplings?
  • How and how well can one favour or exclude 'Higgs impostors'?
Our emphasis is on the 'most wanted' standard particle and its ZZ or ZZ* decays. Yet, our analysis of the Higgs and its possible impostors encompasses the study and characterization of novel neutral bosons of spin 1 and 2 and is extensible to other particles and decays. Slides
Kerstin Tackmann (CERN)
Determination of Vcb and Vub and the b-quark mass from inclusive B decays
Oct 27, 2009

Precision measurements from flavor physics provide stringent constraints on possible New Physics scenarios that are complementary to direct searches in high-energy collisions. The precise determinations of the CKM- matrix elements Vcb and Vub are among the important results of the B factories and require the precise knowledge of the b-quark mass. I will present the current state of the measurements of Vcb, Vub, and the b-quark mass from inclusive B-meson decays at BABAR. I also discuss a new global fit approach to the determination of Vub, called SIMBA, and show first preliminary results. Slides
Alessandro Baldini (INFN, Sezione di Pisa)
First results from the MEG/RE12 experiment at PSI: search for the μ+ → e+ γ decay as a sensitive test of supersymmetric-GUT theories
Sept 29, 2009

The μ →e γ decay, which is absent in the Standard Model, is instead foreseen to occur in supersymmetric grand unified theories (SUSY-GUT) with a branching ratio which might be detectable by the MEG/RE12 experiment. In this seminar, after illustrating the SUSY-GUT predictions for the μ → e γ decay rate and the connection with neutrino oscillations, results from a first period of data taking in 2008 will be shown. The current status of the experiment and the foreseen experimental sensitivity to the μ → e γ decay will finally be presented. Slides
Michel Davier (LAL-Orsay)
New BaBar results on e+ e- → π+ π - and the muon magnetic moment
Sept 22, 2009

A new precise measurement of the e+ e- → π+ π - cross section using the Initial State Radiation method has just been released by the BaBar Collaboration. This analysis presents several advantages over previous determinations. The new data has a strong impact on the calculation of the contribution from hadronic vacuum polarization to the Standard Model prediction of the muon magnetic moment. The state of the comparison with the direct measurement will be discussed. Slides
John March-Russell (Physics Department, University of Oxford)
Exploring String Axions with Astrophysics and Cosmology
Sept 1, 2009

String theory suggests the simultaneous presence of many ultralight axions, possibly populating each decade of mass down to the Hubble scale 10-33eV. Conversely the presence of such a plenitude of axions (an "axiverse") would be evidence for string theory, since it arises due to the topological complexity of the extra-dimensional manifold and is ad hoc in a theory with just the four familiar dimensions. We investigate how several upcoming astrophysical experiments will be observationally exploring the possible existence of such axions over a vast mass range from 10-33eV to 10-10eV. Axions with masses between 10-33eV to 10-28eV can cause a rotation of the CMB polarization that is constant throughout the sky. The predicted rotation angle is independent of the scale of inflation and the axion decay constant, and is within reach of the just launched Planck satellite. Axions in the mass range 10-28eV to 10-18eV give rise to multiple steps in the matter power spectrum, providing us with a snapshot of the axiverse that will be probed by galaxy surveys--such as BOSS, and 21 cm line tomography. Axions in the mass range 10-22eV to 10-10eV can affect the dynamics and gravitational wave emission of rapidly rotating astrophysical black holes through the Penrose superradiance process. When the axion Compton wavelength is of order of the black hole size, the axions develop 'superradiant' atomic bound states around the black hole 'nucleus'. Their occupation number grows exponentially by extracting rotational energy and angular momentum from the ergosphere. For black holes lighter than ~ 107 solar masses accretion cannot replenish the spin of the black hole, creating mass gaps in the spectrum of rapidly rotating black holes that diagnose the presence of destabilizing axions. In particular, the highly rotating black hole in the X-ray binary LMC X-1 implies an upper limit on the decay constant of the QCD axion 2*1017eV, much below the Planck mass. This reach can be improved down to the grand unification scale, the natural string theory value, by observing smaller stellar mass black holes. Slides
Asimina Arvanitaki (University of California at Berkeley)
Decays as Probes of Unification
Aug 25, 2009

Traditional ideas for testing unification involve searching for the decay of the proton and its branching modes. We point out that several astrophysical experiments are now reaching sensitivities that allow them to explore supersymmetric unified theories. In these theories the electroweak-mass DM particle can decay, just like the proton, through dimension six operators with lifetime ~ 1026 sec. Interestingly, this timescale is now being investigated in several experiments including ATIC, PAMELA, HESS, and Fermi. Positive evidence for such decays may be opening our first direct window to physics at the supersymmetric unification scale of MGUT ~ 1016 GeV, as well as the TeV scale. Moreover, in the same supersymmetric unified theories, dimension five operators can lead a weak-scale superparticle to decay with a lifetime of ~ 100 sec. Such decays are recorded by a change in the primordial light element abundances and may well explain the present discord between the measured Li abundances and standard big bang nucleosynthesis, opening another window to unification. These theories make concrete predictions for the spectrum and signatures at the LHC as well as Fermi. Slides
Jodi Cooley-Sekula (Stanford University)
Recoiling Against the Dark Universe: CDMS and the Hunt for Dark Matter
July 7, 2009

The first evidence for dark matter dates back to observations of the Coma cluster made by Fritz Zwicky in 1933. Since that time, astrophysicists and astronomers have produced compelling evidence for the existence of dark matter and determined that it constitutes the bulk of the matter in the Universe. Despite this fact, the composition of the dark matter remains unknown. One compelling candidate for particle dark matter is the Weakly Interacting Massive Particle (WIMP). Working in a low-background environment in the Soudan Mine, located in northern Minnesota, the CDMS experiment is designed to directly detect interactions between WIMPs and nuclei in its target Ge and Si crystals. In this talk I will present the latest results from the CDMS experiment. I will also discuss the current status of SuperCDMS, a 15-kg experiment which is planned for operation in the existing CDMS experimental setup in Soudan, MN and plans for larger future crystal detectors. Slides
Stefan Funk (Stanford University)
Fermi-LAT, HESS and Beyond, Status and Future of Gamma-ray Astronomy
July 6, 2009

The field of gamma-ray astronomy has received considerable attention beyond the high-energy astrophysics community in the recent years. This is in part due to the success of Imaging Atmospheric Cherenkov Telescopes (IACTs) such as HESS, MAGIC and VERITAS, measuring gamma-rays in the energy regime above 100 GeV. All these new facilities have lifted gamma-ray astronomy in the last few years from an exotic discipline with a handful of detected sources to a solid astronomical discipline. In addition, the recent launch of the Fermi Space Telescope (FST) and its main instrument, the Large Area Telescope (LAT) measuring gamma-rays outside Earth's atmosphere in the energy range beyond 100~MeV adds to the attention and excitement. The Fermi-LAT instrument will solidify this discipline by detecting several thousands of new sources and by bridging the energy spectra of ground-based detected VHE gamma-ray sources to well-studies objects at X-ray energies. In this seminar I will discuss the current status of the field, as well as the potential for future observatories. Slides
Thomas Junk (Fermilab)
Searches for the Standard Model Higgs Boson at the Tevatron
June 23, 2009

A broad program has been in place for many years at the CDF and D0 experiments to seek evidence for the Standard Model Higgs boson in the mass range between 100 and 200 GeV/c2. Searches are conducted at low mass (m_H<150 GeV/c2) for processes in which a Higgs boson is produced in association with a weak vector boson and which decays to a pair of b quarks: WH→lvbb, ZH→vvbb, and ZH→llbb. Higgs boson decays to pairs of tau leptons are included in this mass range as well. For higher masses, the decay H→WW is sought in gg→H, WH, ZH, and vector-boson fusion production. Steady improvements have been made in the trigger algorithms, the event selections, and the discriminant analyses, bringing the sensitivity of the combined CDF and D0 searches close to the expected Standard Model production rates, particularly for m_H near 2M_W. The latest CDF and D0 combined result excludes a Standard Model Higgs boson with a mass between 160 and 170 GeV/c2. Slides
Elon Musk (Tesla Motors, SpaceX)
On Energy and Space (N.B. special time 5:00 pm at the Council Chamber)
June 22, 2009

Tesla Motors, SpaceX and SolarCity CEO, founder and chairman, Elon Musk will discuss his vision on the science, technology innovation and business behind sustainable/renewable energy sources and human space travel. Slides
Bernard Sadoulet (Berkely)
The Future of Low Temperature Germanium as Dark Matter Detectors
June 9, 2009

The Weakly Interactive Massive Particles (WIMPs) represent one of the most attractive candidates for the dark matter in the universe. With the combination of experiments attempting to detect WIMP scattering in the laboratory, of searches for their annihilation in the cosmos and of their potential production at the LHC, the next five years promise to be transformative. I will review the role played so far by low temperature germanium detectors in the direct detection of WIMPs. Because of its high signal to noise ratio, the simultaneous measurement of athermal phonons and ionization is so far the only demonstrated approach with zero-background. I will argue that this technology can be extrapolated to a target mass of the order of a tonne at reasonable cost and can keep playing a leading role, complementary to noble liquid technologies. I will describe in particular GEODM, the proposed Germanium Observatory for Dark Matter at the US Deep Underground Science and Engineering Laboratory (DUSEL). Slides
Geoffrey Mills (LANL)
Nus and Anti-Nus from MiniBooNE
May 26, 2009

The MiniBooNE experiment, a short baseline neutrino oscillation experiment currently running at Fermilab, has spent the last two years building up its supply of anti-neutrino data. The collaboration has combed through a good fraction of the anti-neutrino data and the already substantial neutrino data stockpile. The intriguing results will be explored in this seminar, along with future possibilities for short baseline program in the Fermilab booster neutrino beam. Slides
Matteo Palutan (LNF/INFN)
Test of lepton flavor violation with Ke2 decay at KLOE
May 25, 2009

A strong interest in a new measurement of the ratio R_K = Gamma Ke2)/Gamma(Kmu2) has recently arisen. The SM prediction of R_K benefits from cancellation of hadronic uncertainties to a large extent, and therefore can be calculated with high precision. Because of the helicity suppression within the SM, the Ke2 amplitude is sensitive to contributions from physics beyond the SM. Recently, it has been pointed out that in a supersymmetric framework, lepton flavor changing processes mediated by the charged Higgs could occur, in particular in the kaon decay to an electron and tau neutrino. In this scenario, deviations of up to few percent on R_K from SM expectation are quite possible. We present a new measurement of the ratio R_K with 1.3% accuracy performed with the KLOE experiment. The result is based on 2.2 fb-1 of data collected at the Frascati e+e- collider DAFNE. The measurement will be described, and its theoretical implications will be discussed. Slides
Pierre Petroff (LAL/IN2P3)
Measurement of the W boson mass using 1 fb-1 of DZero data from Run II
May 5, 2009

The knowledge of the W boson mass is currently the limiting factor in our ability to tighten the constraints on the mass of the Higgs boson. Improving the measurement of the W boson mass, then, is an important contribution to our understanding of the electroweak interaction, and, potentially, of how electroweak symmetry is broken. This talk will present a measurement of the W boson mass using data taken from 2002-2006 with the Dzero detector, corresponding to a total integrated luminosity of 1 fb-1. Using the W → e ν decay mode we measure: Mw = 80401±21(stat)± 38 (syst) MeV with a total uncertainty of 43 MeV. This agrees with the world average and is slightly more precise than any other single measurement. Slides
Colin Bernet (CNRS/LLR)
Important CMS upgrade: Particle-Flow Event Reconstruction
April 28, 2009

The versatility of the CMS apparatus is exploited in an attempt to identify and reconstruct individually each particle arising from LHC proton-proton collisions with a combination of the information from all sub-detectors. The resulting particle-flow event reconstruction leads to an improved expected performance for jets, taus and missing transverse energy. Slides
Brigitte Bloch-Devaux (IRFU/SPP - CEA Saclay)
Probing non perturbative QCD with kaon decays: precise results by NA48/2
April 21, 2009

The NA48/2 experiment at the CERN SPS has accumulated a total sample of several billions K± decays in 2003-2004. Primarily setup to search for direct CP violation charge asymmetries in K to 3π decays (K± → π ± π0 π0 and K± → π ± π+ π-), the experiment has also collected unprecedented statistics of rare decay modes. The analyses of ~60 millions K± → π ± π0 π0 (K3π) decays and more than 1 million K± → π+ π- e± V (Ke4) decays give independent but complementary approaches to the study of low energy ππ scattering very close to threshold. Precise values of α0 and α2, the Isospin 0 and 2 S-wave ππ scattering lengths, are extracted with an experimental uncertainty of few percents, allowing accurate tests of Chiral Perturbation Theory predictions. These analyses determine simultaneously the form factors (Ke4) and Dalitz plot parameters (K3π) with such good precision to reveal evidence for new genuine terms needed to accurately describe the transition amplitudes. A very fruitful collaboration was developed with several theory groups to bring the control of the theoretical predictions at a level similar to the achieved experimental precision. Slides
Kevin Lannon (University of Notre Dame)
Observation of Single Top at CDF
Mar 31, 2009

On March 4th, 2009, the Tevatron achieved an important milestone with the simultaneous observation of electroweak single top production by the CDF and D0 collaborations. In this talk, I focus on the analyses that achieved observation at CDF. I also discuss the most recent CDF top mass results and give a brief update on the status of the search for the Higgs boson. Slides
Keith Ellis (FNAL)
More precise predictions for hard processes at the Tevatron and the LHC
Mar 24, 2009

I review the status of next-to-leading order QCD as applied to hard processes at the Tevatron and the LHC. Next-to-leading order QCD generally leads to an improvement of the precision of theoretical calculations. I will briefly describe the theoretical advances that lead to optimism that all hard processes can be calculated at NLO. Recent applications of the NLO parton level generator MCFM will be presented. Slides
Achille Stocchi (LAL/IN2P3)
The Super Flavour Factory project
Mar 23, 2009

In this seminar we present the project of a high luminosity asymmetric collider known as Super Flavour Factory (SFF). This machine is capable to reach a luminosity exceeding 1036cm-2sec-1 at the energy of the U(4S) production. This luminosity represents an increase of two order of magnitude with respect to that reached at the present B factories: PEP-II (SLAC) and KEKB (KEK). In this seminar we discuss mainly the physics program of this project. The measurements which can be performed will allow to study in a unique manner the structure of the New Physics beyond the Standard Model, if discovered at LHC at the TeV scale, and/or eventually to extent the domain of the New Physics search at energy scales larger and not accessible to the LHC. We also briefly discuss the recent progress of this project and especially the success of the tests of the new collision schemes ("crab waist scheme") performed in Frascati from beginning 2008 and still on going. The Technical Design Report (TDR) phase has started and important decisions on the approval of this project will be taken soon. Slides
Guennadi Borissov (Lancaster University)
Search for new sources of CP violation at Dzero experiment
Mar 9, 2009

CP violation is studied at Dzero experiment in the channels where the Standard Model predicts a very small value with small systematic uncertainty, so that the contribution of phenomena beyond the SM could become visible. Special features of Dzero detector allow decreasing the systematic uncertainty of CP violation measurements to a very low level, while the steadily increasing statistics makes prospects of detecting new sources of CP violation very promising. We present the most recent results of this study. Slides
JoAnne L. Hewett (SLAC/Stanford)
Supersymmetry Without Prejudice
Feb 23, 2009

We begin an exploration of the physics associated with the general CP-conserving MSSM with Minimal Flavor Violation, the pMSSM. The 19 soft SUSY breaking parameters in this scenario are chosen so as to satisfy all existing experimental and theoretical constraints assuming that the WIMP is a conventional thermal relic, ie, the lightest neutralino. We scan this parameter space twice using both flat and log priors for the soft SUSY breaking mass parameters and compare the results which yield similar conclusions. Detailed constraints from both LEP and the Tevatron searches play a particularly important role in obtaining our final model samples. We find that the pMSSM leads to a much broader set of predictions for the properties of the SUSY partners as well as for a number of experimental observables than those found in any of the conventional SUSY breaking scenarios such as mSUGRA. This set of models can easily lead to atypical expectations for SUSY signals at the LHC. Slides
Claude VALLEE (CPP Marseille and DESY)
Building up the HERA legacy: impact on LHC
Feb 17, 2009

The probe of the proton structure and dynamics at the electron-proton collider HERA is of crucial interest for the predictions of proton-proton processes at the LHC. The H1 and ZEUS experiments are now in the final analysis phase of their full data sets and reaching their ultimate precision to many respects. After a brief summary of the most relevant investigations of new physics performed at HERA at the high energy frontier, the presentation will focus on the latest high-precision measurements of the proton structure and dynamics and their implications for LHC. A review of the present limitations on LHC predictions associated to the parton distributions will be given. The recent breakthrough in precision on the low-x proton structure, resulting from the combination of ZEUS and H1 data, will be presented together with its impact on LHC predictions. Detailed studies of the proton dynamics, especially in the very low-x regime where new QCD effects could appear at LHC, will also be addressed. Slides
Virginia Azzolini (Helsinki U)
Search of New Physics in rare B decays including leptons and/or neutrinos at BaBar
Jan 20, 2009

Rare decays, i.e. decays that are expected to have very small Branching Fractions, are sensitive to new physics beyond the Standard Model. The large sample of BB-bar pairs accumulated by the BaBar experiment at the PEP-II B Factory at the SLAC National Accelerator Laboratory, CA-USA provide good opportunities to measure such decay modes. We present a review of measurements including leptons and/or neutrinos. Slides
Riccardo Cenci (Pisa/SLAC)
Search of exotic new Physics in BaBar
Jan 13, 2009

We present some of the most recent results for the search of new physics using the data collected by BaBar experiment. Lepton flavour violating Tau decay channels are one of the most interesting test for many extensions of the Standard Model and B-factories are pushing the upper limits on those channels down to 1e-8, allowing to constrain the parameter phase space for those extensions. New low-mass invisible scalar particles can be discovered looking at the recoil against a single photon in the Y(3S) events collected in the last months of BaBar operation. In addition, we show also the results for the test of CPT invariance in B-mixing by studying the mixing asymmetry as a function of the sidereal day. Slides
2008 Seminars

Fabrizio Margaroli (Purdue University)
Top physics and Higgs searches in fully hadronic signatures at CDF
Nov 18, 2008

Fully hadronic signatures at hadron colliders are often considered of secondary importance as the QCD production cross section is usually many orders of magnitude higher than the one of interesting signals. I will explain the challenges and the tools used to perform analysis in hadronic signatures at the CDF experiment at the Tevatron, and their relevance in the search for small signals, covering in particular CDF measurements in the Top sector, and the search of the Standard Model Higgs boson. Slides
Mirko Boezio (Istituto Nazionale di Fisica Nucleare)
The Science and First Results of the PAMELA Space Mission
Oct 28, 2008

On the 15th of June 2006 the PAMELA satellite-borne experiment was launched from the Baikonur cosmodrome and it is collecting data since July 2006. The core of the instrument is a silicon-microstrip magnetic spectrometer combined with a time-of-flight system, a silicon-tungsten electromagnetic calorimeter, a shower tail catcher scintillator, a neutron detector and an anticoincidence system. This telescope allows precision studies of the charged cosmic radiation to be conducted over a wide energy range (100 MeV - 100's GeV) with high statistics. The primary scientific goal is the measurement of the antiproton and positron energy spectra in order to search for exotic sources, such as dark matter particle annihilations. PAMELA is also searching for primordial antinuclei (anti-helium) and performing precise measurements of light nuclei and their isotopes for testing cosmic-ray propagation models. Other objectives are the monitoring of the solar activity, the detection of solar flares and the study of the solar and terrestrial relationships in the energetic particle acceleration in the heliosphere. The status of the apparatus will be reviewed and preliminary results concerning the different items and in particular the antiparticle measurements and dark-matter indirect searches will be presented. Slides

Laura Baudis (U Zurich)
Cold Matter Searches with XENON
Oct 27, 2008

The XENON experiment aims to detect weakly interacting massive particles (WIMPs) via their collisions with xenon nuclei, using a low background, two-phase time projection chamber. With 1-ton of ultra pure liquid xenon as target, an energy threshold below 10 keV and a background rejection power above 99.5%, XENON could reach a sensitivity close to 10−46 cm2 for spin-independent WIMP-nucleon cross sections. To verify the XENON approach to direct dark matter detection, a first prototype (XENON10) was developed and operated for a period of several months at the Gran Sasso Underground Laboratory (LNGS) in Italy. XENON10 data have resulted in a 90% C.L. upper limit of 8.8 x 10−44 cm2 for a 100 GeV WIMP. XENON100, a new detector with 170 kg total liquid Xe mass, is currently under commissioning at LNGS; the goal is to start the science run in at the end of 2008. The status and WIMP sensitivity expectations for the new experiment will be presented and compared to the reach of colliders and indirect detection, as well as to theoretical predictions from physics beyond the Standard Model. Slides


Dan Kaplan (Director, IIT Center for Accelerator and Particle Physics)
New Experiments with Antiprotons
Oct 14, 2008

Fermilab operates the world's most intense antiproton source. Newly proposed experiments can use those antiprotons either parasitically during Tevatron Collider running or after the Tevatron Collider finishes in about 2010. For example, the annihilation of 8 GeV antiprotons might make the world's most intense source of tagged D0 mesons, and thus the best near-term opportunity to study charm mixing and, via CP violation, to search for new physics. An experiment using a Penning trap and an atom interferometer could make the world's first measurement of the gravitational force on antimatter. Other potential measurements will also be discussed, to give a flavor of the veritable "physics cornucopia" that could be manifest. Slides


Jianming Qian (University of Michigan)
Hunting for heavy baryons - from Cascade_b to Omega_b
Oct 7, 2008

The large cross section of b quark production at the Fermilab Tevatron collider offers unique opportunities for hunting for heavy baryons that are inaccessible at B factories. In this talk, I will present D0's effort in searching for heavy b baryons and our latest result on the observation of the omega_b baryon, fully reconstructed from its decay to J/psi and Omega. Slides

Claudia Patrignani (University and INFN Genova)
Observation of the eta_b(1S) in Y(3S)-> gamma eta_b and bottomonium physics at BaBar
Sept 16, 2008

We report the observation of the bottomonium ground state, eta_b(1S), based on a study of the inclusive photon spectrum of (109±1) millions Upsilon(3S) recorded at the Upsilon(3S) energy with the BABAR detector at the PEP-II B factory at SLAC. The hyperfine Upsilon(1S)-eta_b(1S) mass splitting, a key ingredient in many theoretical calculations, is 71.4 {+2.3} {-3.1} (stat) ± 2.7(syst) MeV/c2. The precision of our measurement will allow, among others, a more precise determination of the lattice spacing and new precision determinations of alpha_s. Other results on bottomonium physics from BABAR will also be presented. Slides

Andy Haas (Columbia/D0), Ben Kilminster(FNAL/CDF)
Higgs Results From the Tevatron

The CDF and D0 experiments at Fermilab's Tevatron are now becoming sensitive to the standard model Higgs boson. A recent combination of the CDF and D0 results excludes a Higgs mass of 170 GeV at 95% CL. In a joint format a speaker for each of the experiments will discuss the CDF and D0 results that contribute to these limits. For lower Higgs boson masses, as are preferred by electroweak constraints, the progress towards achieving standard model sensitivity through the combination of multiple Higgs decay and production modes will be presented.
Sept 8, 2008

Mirko Boezio (Istituto Nazionale di Fisica Nucleare)
The Science and First Results of the PAMELA Space Mission
Sep 2, 2008

On the 15th of June 2006 the PAMELA satellite-borne experiment was launched from the Baikonur cosmodrome and it is collecting data since July 2006. The core of the instrument is a silicon-microstrip magnetic spectrometer combined with a time-of-flight system, a silicon-tungsten electromagnetic calorimeter, a shower tail catcher scintillator, a neutron detector and an anticoincidence system. This telescope allows precision studies of the charged cosmic radiation to be conducted over a wide energy range (100 MeV - 100's GeV) with high statistics. The primary scientific goal is the measurement of the antiproton and positron energy spectra in order to search for exotic sources, such as dark matter particle annihilations. PAMELA is also searching for primordial antinuclei (anti-helium) and performing precise measurements of light nuclei and their isotopes for testing cosmic-ray propagation models. Other objectives are the monitoring of the solar activity, the detection of solar flares and the study of the solar and terrestrial relationships in the energetic particle acceleration in the heliosphere. The status of the apparatus will be reviewed and preliminary results concerning the different items and in particular the antiparticle measurements and dark-matter indirect searches will be presented. Slides Nature problematics

Heinz W. Gaeggelere (PSI and Univesity of Bern)
Happy landing on the island of superheavy elements
Aug 19, 2008

The talk summarizes recent chemical studies with elements 112 and 114. These elements are interesting for chemists since they have filled electron (sub)shells, 6d107s2 for element 112 and 6d107s27p1/22 for element 114. Due to relativistic effects on the electronic orbitals (caused by the high Coulomb attraction between the atomic electrons and the nucleus) pronounced spin-orbit coupling occurs. This leads e.g. to a strong separation of the 7p1/2 and 7p3/2 levels. This initiated speculations, that these two elements might behave more like noble gases rather than being similar to their homologues in the Periodic Table. Based on 5 atoms of element 112 it was possible to proof its similarity with Hg from the same group of Periodic Table. Ongoing studies with element 114 – currently with 4 identified atoms - do not yield evidence for a similarity with its neighbour in the same group, Pb, but rather with a very volatile element such as a heavy noble gas. Slides

Gordy Kane (Univesity of Michigan)
Dark matter searches from the galaxy to the LHC - recent hints and coming progress
Aug 5, 2008

We discuss the possible galactic positron excess and constraints on interpreting it as dark matter annihilation. We consider wino and higgsino wimps that provide the local relic density and a positron excess (which implies the relic density is non-thermal in origin and important consequences for cosmological history and underlying theories), comment on how to confirm and study these issues at LHC, and on the relation to direct detection experiments. Slides, live webcast, video recording

Tim Christiansen (CERN/CMS), Alessandro Cerri (CERN/ATLAS)
ATLAS & CMS Commissioning with First Data

In a joint format a speaker for ATLAS and one for CMS will present the current work of the experiments in preparation for the LHC startup and data-taking.
July 21, 2008

Charles Plager (UCLA/CDF)
How charming is the Truth: A search for Top Flavor Changing Neutral Currents t → Zc
July 1, 2008

Starting with an introduction to top quark physics and properties of the top quark, I will give an in depth look at CDF's search for top flavor changing neutral currents, in particular t→Zc.

Alexander Glazov (DESY)
The final measurement of the direct CP violation parameter Re(ε'/ε) by the KTeV collaboration
June 30, 2008

The final measurement of Re(ε'/ε) based on the full KTeV dataset is presented. The dataset contains about 15 million K→ π0 π0 and 70 million K→ π+ π+ decays allowing for significant improvement in precision compared to the previous KTeV result. The KTeV data are also used for new tests of the CPT symmetry. The value of Re(ε'/ε) is consistent with one obtained by the NA48 collaboration, the world average result provides a measurement of the direct CP violation with better than 10% precision.

Friedrich Dydak (CERN)
Results from HARP-CDP or The irresistible Power of Truth
June 24, 2008

Surprisingly, cross-sections of hadron production off nuclei are uncertain by factors of up to three. A systematic measurement programme was undertaken with the HARP spectrometer at CERN, motivated by the need to have precise cross-sections for the understanding of the "LSND puzzle", for the design of a neutrino factory, for the Monte Carlo simulation of LHC data, and for other issues. We present measurements of the ratio of negative to positive pions produced by protons with kinetic energy of 800 MeV, and discuss them in the context of our simulation of signals and backgrounds in the LSND experiment. We present double-differential cross-sections measured in the large-angle HARP spectrometer. Our cross-sections disagree grossly with those being published by the HARP Collaboration. The origin of the disagreement is understood and we shall explain what went wrong in the data analysis of the HARP Collaboration. Our measurements were used to test hadron production models in the GEANT4 simulation tool kit. We observe that all currently implemented models disagree strongly with our data.

Giulia Manca, INFN/Cagliari
Searches for Chargino-Neutralino Associated Production in Trilepton Events at CDF
June 17, 2008

I will report the results of the search for associated production of the supersymmetric lightest chargino and the next-to-lightest neutralino in several multi-lepton final states using approximately 2 fb-1 of 1.96 TeV pbar data collected by the CDF-II detector at the Fermilab Tevatron. The number of events observed in each channel are consistent with the Standard Model expectactions. Using these results we set upper limits on the cross-section times branching ratio as a function of the chargino mass in minimal supergravity models.

Maurizio Pierini, CERN
Constraints on new physics from b→s hadronic decays at the Babar
June 3, 2008

We present the status of time-dependent and time-integrated measurements of b→s hadronic decays and we discuss their phenomenological implication. Being dominated by penguin contributions, these decay modes are sensitive to virtual effects from heavy particles running in the loop and can probe the presence of physics beyhond the Standard Model. In addition, they allow to discriminate among the available hadronic matrix elements calculations. We review the experimental techniques used in the analysis, the status of the experimental measurements and the perspectives for the next generation of flavor experiments.

Marcella Bona, CERN
Measurements of the Unitarity Triangle angles at the B factories
May 27, 2008

With the advent of the asymmetric B factories, Belle and BaBar, the CP violation in the B sector has been firmly estabilished, the sin2β measurement being now a precision measurement at the % level. B factories have accumulated an impressive statistics and this gives enormous possibilities for exploring also the other angles of the Unitarity Triangle. A review of the current experimental status and perspectives on the measurements of the Unitarity Triangle angles will be given: we will start with the by-now benchmark extraction of the β value in charmonium final states, assessing possible theory contributions to the SM prediction. Then we will discuss the determination of the phase of the CKM matrix through the study of b →c and b →u transitions in (NP free) B decays to charmed mesons. Finally we will address the (NP sensitive) charmless b →d and b →s decays, focusing on the B →ππ measurements related to alpha angle. A final glance at the state of the art in the flavour sector of the SM (and beyond) will be given.
  • Aubert et al. [BABAR Collaboration] "Improved Measurement of CP Violation in Neutral B Decays to c cbar s" Phys. Rev. Lett. 99 (2007) 171803 [arXiv:hep-ex/0703021].
  • B. Aubert et al. [BABAR Collaboration], "Observation of CP violation in B0 --> K+ pi- and B0 --> pi+ pi-" Phys.\ Rev.\ Lett.\ {\bf 99} (2007) 021603 [arXiv:hep-ex/0703016].
  • B. Aubert et al. [BABAR Collaboration], "Improved measurement of the CKM angle gamma in B^-+ -> D^(*) K^(*)-+ decays with a Dalitz plot analysis of D decays to K_S0 pi^+ pi^- and K_S0 K^+K^-" Submitted to Physical Review D arXiv:0804.2089 [hep-ex].

Peter Geltenbort,Institut Laue-Langevin Grenoble, France
Ultra-Cold Neutrons and Lifetime Measurements at the Institut Laue-Langevin, Grenoble
May 13, 2008

Due to their outstanding property to be storable and hence observable for long periods of time (several hundreds of seconds) in suitable material or magnetic traps, ultra-cold neutrons (UCN) with energies around 100 neV are an unique tool to study fundamental properties of the free neutron. A brief introduction to the Institut Laue-Langevin (ILL) in Grenoble, France, which is a world leader in academic research with neutrons will be given. The scope of fundamental physics studies with neutrons is outlined. The main instruments provided for such studies are briefly introduced and some past and current flagship experiments with ultra-cold neutrons (UCN) in this field (electric dipole moment, quantum states) are highlighted. The measurement of the lifetime of the free neutron is one of the important experiments in fundamental physics. Together with the determination of one of the correlation parameters characterizing neutron decay it allows tests of the Standard Model. Furthermore, the neutron lifetime plays an important role in Big-Bang Nucleosynthesis cosmology. Up to 180 s after the big-bang nuclei with more than one nucleon are unstable. The neutron lifetime determines how many neutrons have decayed up to this moment and hence the relative helium abundance in the universe. The different methods to measure the lifetime of the free neutron are reviewed and the latest experiments using storage of UCN at the ILL are described in detail.
  • Improved experimental limit on the electric dipole moment of the neutron Baker C.A., Doyle D.D., Geltenbort P., Green K., Van der Grinten M.G.D., Harris P.G., Iaydjiev P., Ivanov S.N., May D.J.R., Pendlebury J.M., Richardson J.D., Shiers D., Smith K.F. Physical Review Letters 97, 131801\_1-131801\_4 (2006)
  • Measurement of the neutron lifetime using a gravitational trap and a low-temperature Fomblin coating Serebrov A., Varlamov V., Kharitonov A., Fomin A., Pokotilovski Y., Geltenbort P., Butterworth J., Krasnoschekova I., Lasakov M., Tal'Daev R., Vassiljev A., Zherebtsov O. Physics Letters B 605, 72-78 (2005)
  • First ever storage of ultracold neutrons in a magnetic trap made of permanent magnets Ezhov V.F., Andreev A.Z., Glushkov A.A., Glushkov A.G., Groshev M.N., Knyazkov V.A., Krygin G.B., Ryabov V.L. Serebrov A.P., Bazarov B.A., Geltenbort P., Hartman F.J., Paul S., Picker R., Zimmer O., Kovrizhnykh N.A. Journal of Research of the National Institute of Standards and Technology 110, 345-350 (2005)

Yosef Nir, Weizmann Institute of Science
Understanding flavour at the LHC
May 6, 2008

Huge progress in flavour physics has been achieved by the two B-factories and the Tevatron experiments. This progress has, however, deepened the new physics flavour puzzle: If there is new physics at the TeV scale, why aren't flavour changing neutral current processes enhanced by orders of magnitude compared to the standard model predictions? The forthcoming ATLAS and CMS experiments can potentially solve this puzzle. Perhaps even more surprisingly, these experiments can potentially lead to progress in understanding the standard model flavour puzzle: Why is there smallness and hierarchy in the flavour parameters? Thus, a rich and informative flavour program is awaiting us not only in the flavour-dedicated LHCb experiment, but also in the high-pT ATLAS and CMS experiments.

Kai-Feng Chen, National Taiwan U
Difference in direct charge-parity violation between charged and neutral B meson decays
April 29, 2008

Equal amounts of matter and antimatter are predicted to have been produced in the Big Bang, but our observable Universe is clearly matter-dominated. One of the prerequisites1 for understanding this elimination of antimatter is the nonconservation of charge-parity (CP) symmetry. So far, two types of CP violation have been observed in the neutral K meson (K0) and B meson (B0) systems: CP violation involving the mixing between K0 and its antiparticle (and likewise for B0 and B0bar ), and direct CP violation in the decay of each meson. The observed effects for both types of CP violation are substantially larger for the B0 meson system. However, they are still consistent with the standard model of particle physics, which has a unique source9 of CP violation that is known to be too small10 to account for the matter-dominated Universe. Here we report that the direct CP violation in charged BK0 decay is different from that in the neutral B0 counterpart. The direct CP-violating decay rate asymmetry, (that is, the difference between the number of observed B-K-0 event versus B+ to K+ pi0 events, normalized to the sum of these events) is measured to be about +7%, with an uncertainty that is reduced by a factor of 1.7 from a previous measurement. However, the asymmetry for versus B0 to K+pi- is at the -10% level. Although it is susceptible to strong interaction effects that need further clarification, this large deviation in direct CP violation between charged and neutral B meson decays could be an indication of new sources of CP violation which would help to explain the dominance of matter in the Universe.


Jeannine Wagner-Kuhr, Karlsruhe (N.B. Council Chamber)
Single top results from CDF
April 22, 2008

The Tevatron proton anti-proton collider at Fermilab with a center of mass energy of 1.96 TeV is at the moment the only place to produce the heaviest known elementary particle, the top-quark. In the last years data corresponding to an integrated luminosity of more than 3/fb have been collected with the CDF experiment whereof about 2/fb have been reconstructed and analysed. Although the top-quark is now known more than one decade only the top-pair production via the strong interaction is well established while there is evidence for, but no observation of single top-quark production via the electroweak interaction. The main challenge of the single top-quark search at the Tevatron is the huge background from W+jets events and QCD events, which makes the use of advanced multivariate techniques essential. The recent single top analyses using either the matrix element method, neural networks, likelihood discriminants or boosted decision trees as well as the combination of the former three analyses will be presented and the results from CDF will be compared with the results from D∅.


Guillelmo Gómez-Ceballos, MIT
Measurement of Bs mixing parameters from Bs → J/&psi φ decays at CDF and D∅
March 18, 2008

CP violation in B0 and B+ decays has already been extensively investigated at the B-factories over the last years, while the corresponding knowlege in the B0s system has been lacking so far. B0s mesons are produced with large cross section at the Tevatron collider. Following the measurement of the B0s to B0s oscillation frequency in 2006, the D∅ and CDF experiments have now investigated CP asymmetries in B0s meson decays. We report on the first flavor-tagged analyses from both experiments using B0s decays to J/ψ φ. This channel is sensitive not only to the width difference ΔΓ in the B0s system but also to the (CP violating) weak phase βs.


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