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Book
1 online resource (45 p. ) : digital, PDF file.
Fermilab is executing Laboratory Directed Research and Development (LDRD) as outlined by order DOE O 413.2B in order to enhance and realize the mission of the laboratory in a manner that also supports the laboratory’s strategic objectives and the mission of the Department of Energy. LDRD funds enable scientific creativity, allow for exploration of “high risk, high payoff” research, and allow for the demonstration of new ideas, technical concepts, and devices. LDRD also has an objective of maintaining and enhancing the scientific and technical vitality of Fermilab.
Book
1 online resource (14 p. ) : digital, PDF file.
After initiation by the Fermilab Laboratory Director, a team from the senior Laboratory leadership and a Laboratory Directed Research and Development (LDRD) Advisory Committee developed an implementation plan for LDRD at Fermilab for the first time. This implementation was captured in the approved Fermilab 2014 LDRD Program Plan and followed directions and guidance from the Department of Energy (DOE) order, DOE O 413.2B, a “Roles, Responsibilities, and Guidelines, …” document, and examples of best practices at other DOE Office of Science Laboratories. At Fermilab, a FY14 midyear Call for Proposals was issued. A LDRD Selection Committee evaluated those proposals that were received and provided a recommendation to the Laboratory Director who approved seven LDRD projects. This Annual Report focuses on the status of those seven projects and provides an overview of the current status of LDRD at Fermilab. The seven FY14 LDRD approved projects had a date of initiation late in FY14 such that this report reflects approximately six months of effort approximately through January 2015. The progress of these seven projects, the subsequent award of six additional new projects beginning in FY15, and preparations for the issuance of the FY16 Call for Proposals indicates that LDRD is now integrated into the overall annual program at Fermilab. All indications are that LDRD is improving the scientific and technical vitality of the Laboratory and providing new, novel, or cutting edge projects carried out at the forefront of science and technology and aligned with the mission and strategic visions of Fermilab and the Department of Energy.
Book
22 p. : digital, PDF file.
The Fermi National Accelerator Laboratory (FNAL) is conducting a Laboratory Directed Research and Development (LDRD) program. Fiscal year 2015 represents the first full year of LDRD at Fermilab and includes seven projects approved mid-year in FY14 and six projects approved in FY15. One of the seven original projects has been completed just after the beginning of FY15. The implementation of LDRD at Fermilab is captured in the approved Fermilab 2015 LDRD Annual Program Plan. In FY15, the LDRD program represents 0.64% of Laboratory funding. The scope of the LDRD program at Fermilab will be established over the next couple of years where a portfolio of about 20 on-going projects representing approximately between 1% and 1.5% of the Laboratory funding is anticipated. This Annual Report focuses on the status of the current projects and provides an overview of the current status of LDRD at Fermilab.
Book
1 online resource (14 p. ) : digital, PDF file.
Fermilab is executing Laboratory Directed Research and Development (LDRD) as outlined by order DOE O 413.2B in order to enhance and realize the mission of the laboratory in a manner that also supports the laboratory’s strategic objectives and the mission of the Department of Energy. LDRD funds enable scientific creativity, allow for exploration of “high risk, high payoff” research, and allow for the demonstration of new ideas, technical concepts, and devices. LDRD also has an objective of maintaining and enhancing the scientific and technical vitality of Fermilab. LDRD is able to fund employee-initiated proposals that address the current strategic objectives and better position Fermilab for future mission needs. The request for such funds is made in consideration of the investment needs, affordability, and directives from DOE and Congress. Review procedures of the proposals will insure that those proposals which most address the strategic goals of the DOE and the Laboratory or which best position Fermilab for the future will be recommended to the Laboratory Director who has responsibility for approval. The execution of each approved project will be the responsibility of the Principal Investigator, PI, who will follow existing Laboratory guidelines to ensure compliance with safety, environmental, and quality assurance practices. A Laboratory Director-appointed LDRD Coordinator will work with Committees, Laboratory Management, other Fermilab Staff, and the PI’s to oversee the implementation of policies and procedures of LDRD and provide the management and execution of this Annual Program Plan. FY16 represents third fiscal year in which LDRD has existed at Fermilab. The number of preliminary proposals (117) submitted in response to the LDRD Call for Proposals indicates very strong interest of the program within the Fermilab community. The first two Calls have resulted in thirteen active LDRD projects – and it is expected that between five and seven new projects will be approved in response to the FY16 Call for Proposals. The implementation of the program compared with FY15 is mostly unchanged except that the program is on the expected normal fiscal year calendar cycle with new projects starting at the beginning of the fiscal year. Because of this, there is some expanded discussion that the Laboratory Director may decide to initiate mid-year Late Start or Strategic- Hire LDRD projects.
The 35-ton prototype will test technology potentially slated for the Deep Underground Neutrino Experiment.
Book
1 online resource.
Current designs for muon accelerators require high-gradient radio frequency (RF) cavities to be placed in solenoidal magnetic fields. These fields help contain and efficiently reduce the phase space volume of source muons in order to create a usable muon beam for collider and neutrino experiments. In this context and in general, the use of RF cavities in strong magnetic fields has its challenges. It has been found that placing normal conducting RF cavities in strong magnetic fields reduces the threshold at which RF cavity breakdown occurs. To aid the effort to study RF cavity breakdown in magnetic fields, it would be helpful to have a diagnostic tool which can localize the source of breakdown sparks inside the cavity. These sparks generate thermal shocks to small regions of the inner cavity wall that can be detected and localized using microphones attached to the outer cavity surface. Details on RF cavity sound sources as well as the hardware, software, and algorithms used to localize the source of sound emitted from breakdown thermal shocks are presented. In addition, results from simulations and experiments on three RF cavities, namely the Aluminum Mock Cavity, the High-Pressure Cavity, and the Modular Cavity, are also given. These results demonstrate the validity and effectiveness of the described technique for acoustic localization of breakdown.
Book
1 online resource.
Large mass splittings between new scalars in two-Higgs-doublet models (2HDM) open a key avenue to search for these new states via exotic heavy Higgs decays. We discuss in detail the different search channels for these new scalars at the LHC in the presence of a sizable mass splitting, i.e. a hierarchical 2HDM scenario, taking into account the theoretical and experimental constraints. We provide benchmark planes to exploit the complementarity among these searches, analyzing their potential to probe the hierarchical 2HDM parameter space during LHC Run 2.
Book
Article No. 179 : digital, PDF file.
Here we present a Next-to-Next-to Leading Order (NNLO) calculation of the production of a Higgs boson in association with a massive vector boson. We also include the decays of the unstable Higgs and vector bosons, resulting in a fully flexible parton-level Monte Carlo implementation. We also include all $\mathcal{O}(\alpha_s^2)$ contributions that occur in production for these processes: those mediated by the exchange of a single off-shell vector boson in the $s$-channel, and those which arise from the coupling of the Higgs boson to a closed loop of fermions. Final states of interest for Run II phenomenology were studied, namely $H\rightarrow b\bar{b}$, $\gamma\gamma$ and $WW^*$. The treatment of the $H\rightarrow b\bar{b}$ decay includes QCD corrections at NLO. We use the recently developed $N$-jettiness regularization procedure, and study its viability in the presence of a large final-state phase space by studying $pp\rightarrow V(H\rightarrow WW^*) \rightarrow$ leptons.
The decorrelation in the azimuthal angle between the most forward and the most backward jets (Mueller-Navelet jets) is measured in data collected in pp collisions with the CMS detector at the LHC at $\sqrt{s} =$ 7 TeV. The measurement is presented in the form of distributions of azimuthal-angle differences, $\Delta\phi$, between the Mueller-Navelet jets, the average cosines of $(\pi-\Delta\phi)$, $2(\pi-\Delta\phi)$, and $3(\pi-\Delta\phi)$, and ratios of these cosines. The jets are required to have transverse momenta, $p_{\mathrm{T}}$, in excess of 35 GeV and rapidities, $ y , of less than 4.7. The results are presented as a function of the rapidity separation, $\Delta{y}$, between the Mueller-Navelet jets, reaching $\Delta{y}$ up to 9.4 for the first time. The results are compared to predictions of various Monte Carlo event generators and to analytical predictions based on the DGLAP and BFKL parton evolution schemes.
Here, we study angular observables in the $ {e}^{+}{e}^{-}\to ZH\to {\ell}^{+}{\ell}^{-}b\overline{b} $ channel at future circular e$^{+}$ e$^{-}$ colliders such as CEPC and FCC-ee. Taking into account the impact of realistic cut acceptance and detector effects, we forecast the precision of six angular asymmetries at CEPC (FCC-ee) with center-of-mass energy $ \sqrt{s}=240 $ GeV and 5 (30) ab$^{-1}$ integrated luminosity. We then determine the projected sensitivity to a range of operators relevant for he Higgs-strahlung process in the dimension-6 Higgs EFT. Our results show that angular observables provide complementary sensitivity to rate measurements when constraining various tensor structures arising from new physics. We further find that angular asymmetries provide a novel means of both probing BSM corrections to the HZγ coupling and constraining the “blind spot” in indirect limits on supersymmetric scalar top partners.
Book
1 online resource.
Soft function relevant for transverse-momentum resummation for Drell-Yan or Higgs production at hadron colliders are computed through to three loops in the expansion of strong coupling, with the help of bootstrap technique and supersymmetric decomposition. The corresponding rapidity anomalous dimension is extracted. An intriguing relation between anomalous dimensions for transverse-momentum resummation and threshold resummation is found.
Book
1 online resource.
A method, system, and apparatus for installing channel nuts includes a shank, a handle formed on a first end of a shank, and an end piece with a threaded shaft configured to receive a channel nut formed on the second end of the shaft. The tool can be used to insert or remove a channel nut in a channel framing system and then removed from the channel nut.
Book
1 online resource.
The cross section for coherent J/psi photoproduction accompanied by at least one neutron on one side of the interaction point and no neutron activity on the other side, X[n]0[n], is measured with the CMS experiment in ultra-peripheral PbPb collisions at sqrt(s[NN]) = 2.76 TeV. The analysis is based on a data sample corresponding to an integrated luminosity of 159 inverse microbarns, collected during the 2011 PbPb run. The J/psi mesons are reconstructed in the dimuon decay channel, while neutrons are detected using zero degree calorimeters. The measured cross section is d sigma[coh, X[n]0[n]]/d y(J/psi) = 0.36 +/- 0.04\ (stat) +/- 0.04 (syst) mb in the rapidity interval 1.8<abs(y)<2.3. Using a model for the relative rate of coherent photoproduction processes, this X[z, n, z] measurement gives a total coherent photoproduction cross section of d sigma[coh]/d y(J/psi) = 1.82 +/- 0.22 (stat) +/- 0.20 (syst) +/- 0.19 (theo) mb. The data strongly disfavour the impulse approximation model prediction, indicating that nuclear effects are needed to describe coherent J/psi photoproduction in gamma + Pb interactions. The data are found to be consistent with the leading twist approximation, which includes nuclear gluon shadowing.
A search for anomalous pseudoscalar couplings of the Higgs boson H to electroweak vector bosons V (= W or Z) in a sample of proton-proton collision events corresponding to an integrated luminosity of 18.9 fb$^{-1}$ at a center-of-mass energy of 8 TeV is presented. Events consistent with the topology of associated VH production, where the Higgs boson decays to a pair of bottom quarks and the vector boson decays leptonically, are analyzed. The consistency of data with a potential pseudoscalar contribution to the HVV interaction, expressed by the effective pseudoscalar cross section fractions $f_{a_3}$, is assessed by means of profile likelihood scans. Results are given for the VH channels alone and for a combined analysis of the VH and previously published H $\rightarrow$ VV channels. Assuming the standard model ratio of the coupling strengths of the Higgs boson to top and bottom quarks, $ f_{a_3}^{\mathrm{ZZ}}>0.0034$ is excluded at 95% confidence level in the combination.
Book
23 p. : digital, PDF file.
We further develop and extend a recent perturbative framework for neutrino oscillations in uniform matter density so that the resulting oscillation probabilities are accurate for the complete matter potential versus baseline divided by neutrino energy plane. This extension also gives the exact oscillation probabilities in vacuum for all values of baseline divided by neutrino energy. The expansion parameter used is related to the ratio of the solar to the atmospheric $\Delta m^2$ scales but with a unique choice of the atmospheric $\Delta m^2$ such that certain first-order effects are taken into account in the zeroth-order Hamiltonian. Using a mixing matrix formulation, this framework has the exceptional feature that the neutrino oscillation probability in matter has the same structure as in vacuum, to all orders in the expansion parameter. It also contains all orders in the matter potential and $\sin\theta_{13}$. It facilitates immediate physical interpretation of the analytic results, and makes the expressions for the neutrino oscillation probabilities extremely compact and very accurate even at zeroth order in our perturbative expansion. Furthermore, the first and second order results are also given which improve the precision by approximately two or more orders of magnitude per perturbative order.
Book
p. 1-9 : digital, PDF file.
W boson mass measurement is sensitive to QED radiative corrections due to virtual photon loops and real photon emission. The largest shift in the measured mass, which depends on the transverse momentum spectrum of the charged lepton from the boson decay, is caused by the emission of real photons from the final-state lepton. There are a number of calculations and codes available to model the final-state photon emission. We perform a detailed study, comparing the results from <sc>HORACE</sc> and <sc>PHOTOS</sc> implementations of the final-state multiphoton emission in the context of a direct measurement ofW boson mass at Tevatron. Mass fits are performed using a simulation of the CDF II detector.</p>
The production of a Higgs boson in association with a vector boson at the Tevatron offers a unique opportunity to study models for the Higgs boson with exotic spin J and parity P assignments. At the Tevatron the V H system is produced near threshold. Different JP assignments of the Higgs boson can be distinguished by examining the behavior of the cross section near threshold. The relatively low backgrounds at the Tevatron compared to the LHC put us in a unique position to study the direct decay of the Higgs boson to fermions. If the Higgs sector is more complex than predicted, studying the spin and parity of the Higgs boson in all decay modes is important. In this Thesis we will examine the WH → ℓνb¯b production and decay mode using 9.7 fb<sup>-1</sup> of data collected by the D0 experiment in an attempt to derive constraints on models containing exotic values for the spin and parity of the Higgs boson. In particular, we will examine models for a Higgs boson with JP = 0- and JP = 2+. We use a likelihood ratio to quantify the degree to which our data are incompatible with exotic JP predictions for a range of possible production rates. Assuming the production cross section times branching ratio of the signals in the models considered is equal to the standard model prediction, the WH → ℓνb¯b mode alone is unable to reject either exotic model considered. We will also discuss the combination of the ZH → ℓℓb¯b, WH → ℓνb¯b, and V H → ννb¯b production modes at the D0 experiment and with the CDF experiment. When combining all three production modes at the D0 experiment we reject the JP = 0- and JP = 2+ hypotheses at the 97.6% CL and at the 99.0% CL, respectively, when assuming the signal production cross section times branching ratio is equal to the standard model predicted value. When combining with the CDF experiment we reject the JP = 0- and JP = 2+ hypotheses with significances of 5.0 standard deviations and 4.9 standard deviations, respectively.abstract
Book
1 online resource (39 p. ) : digital, PDF file.
In this study, the quark-gluon plasma is studied via medium-induced changes to correlations between jets and charged particles in PbPb collisions compared to pp reference data. This analysis uses data sets from PbPb and pp collisions with integrated luminosities of 166 inverse microbarns and 5.3 inverse picobarns, respectively, collected at $ \sqrt{s_{\mathrm{NN}}}=2.76 $ TeV. The angular distributions of charged particles are studied as a function of relative pseudorapidity (Δη) and relative azimuthal angle (ΔΦ) with respect to reconstructed jet directions. Charged particles are correlated with all jets with transverse momentum (p<sub>T</sub>) above 120 GeV, and with the leading and subleading jets (the highest and second-highest in p<sub>T</sub>, respectively) in a selection of back-to-back dijet events. Modifications in PbPb data relative to pp reference data are characterized as a function of PbPb collision centrality and charged particle p<sub>T</sub>. A centrality-dependent excess of low-p<sub>T</sub> particles is present for all jets studied, and is most pronounced in the most central events. This excess of low-p<sub>T</sub> particles follows a Gaussian-like distribution around the jet axis, and extends to large relative angles of Δη ≈ 1 and ΔΦ ≈ 1.
Book
1 online resource.
We present a comparison between several observational tests of the post-reionization IGM and the numerical simulations of reionization completed under the Cosmic Reionization On Computers (CROC) project. We show that CROC simulations reproduce "out-of-the-box" the observed distributions of Gunn-Peterson optical depths, underscoring the importance of self-consistent modeling of radiative transfer. We also show that CROC simulations match well the observed distributions of dark gaps from SDSS quasars. Finally, we introduce a novel statistical probe of the small-scale structure in the IGM: heights and widths of transmission peaks. Simulations match the peak height distributions reasonably well, but do not reproduce the observed abundance of wide peaks.
Book
14 p. : digital, PDF file.
A strong instrumentation and detector R&D program has enabled the current generation of cosmic frontier surveys. A small investment in R&D will continue to pay dividends and enable new probes to investigate the accelerated expansion of the universe. Instrumentation and detector R&D provide critical training opportunities for future generations of experimentalists, skills that are important across the entire Department of Energy High Energy Physics program.