3,792 research outputs found
Standard model explanation of a CDF dijet excess in Wjj
Full text linkWe demonstrate the recent observation of a peak in the dijet invariant mass
of the Wjj signal observed by the CDF Collaboration can be explained as the
same upward fluctuation observed by CDF in single-top-quark production. In
general, both t-channel and s-channel single-top-quark production produce
kinematically induced peaks in the dijet spectrum. Since CDF used a Monte Carlo
simulation to subtract the single-top backgrounds instead of data, a peak in
the dijet spectrum is expected. The D0 Collaboration has a small upward
fluctuation in their published t-channel data; and hence we predict they would
see at most a small peak in the dijet invariant mass spectrum of Wjj if they
follow the same procedure as CDF.Comment: 3 pg., 2 figs, revtex, minor clarifications, to appear in Phys. Rev.
Searches for Physics Beyond the Standard Model at Colliders
Full text linkAll experimental measurements of particle physics today are beautifully
described by the Standard Model. However, there are good reasons to believe
that new physics may be just around the corner at the TeV energy scale. This
energy range is currently probed by the Tevatron and HERA accelerators and
selected results of searches for physics beyond the Standard Model are
presented here. No signals for new physics have been found and limits are
placed on the allowed parameter space for a variety of different particles.Comment: Proceedings for 2007 Europhysics Conference on High Energy Physics,
Manchester, July 200
Measurements of the Production, Decay and Properties of the Top Quark: A Review
Get PDFWith the full Tevatron Run II and early LHC data samples, the opportunity for
furthering our understanding of the properties of the top quark has never been
more promising. Although the current knowledge of the top quark comes largely
from Tevatron measurements, the experiments at the LHC are poised to probe
top-quark production and decay in unprecedented regimes. Although no current
top quark measurements conclusively contradict predictions from the standard
model, the precision of most measurements remains statistically limited.
Additionally, some measurements, most notably the forward-backward asymmetry in
top quark pair production, show tantalizing hints of beyond-the-Standard-Model
dynamics. The top quark sample is growing rapidly at the LHC, with initial
results now public. This review examines the current status of top quark
measurements in the particular light of searching for evidence of new physics,
either through direct searches for beyond the standard model phenomena or
indirectly via precise measurements of standard model top quark properties
Prompt Decays of General Neutralino NLSPs at the Tevatron
Full text linkRecent theoretical developments have shown that gauge mediation has a much
larger parameter space of possible spectra and mixings than previously
considered. Motivated by this, we explore the collider phenomenology of gauge
mediation models where a general neutralino is the lightest MSSM superpartner
(the NLSP), focusing on the potential reach from existing and future Tevatron
searches. Promptly decaying general neutralino NLSPs can give rise to final
states involving missing energy plus photons, Zs, Ws and/or Higgses. We survey
the final states and determine those where the Tevatron should have the most
sensitivity. We then estimate the reach of existing Tevatron searches in these
final states and discuss new searches (or optimizations of existing ones) that
should improve the reach. Finally we comment on the potential for discovery at
the LHC.Comment: 41 pages, minor changes, added refs and discussion of previous
literatur
Taking a Razor to Dark Matter Parameter Space at the LHC
Full text linkDark matter (DM) has been searched for at colliders in a largely model
independent fashion by looking for an excess number of events involving a
single jet, or photon, and missing energy. We investigate the possibility of
looking for excesses in more inclusive jet channels. Events with multiple jets
contain more information and thus more handles to increase the signal to
background ratio. In particular, we adapt the recent CMS "razor" analysis from
a search for supersymmetry to a search for DM. We consider simplified models
where DM is a Dirac fermion that couples to the quarks of the Standard Model
(SM) through exchange of vector or axial-vector mediators or to gluons through
scalar exchange. We consider both light and heavy (leading to effective contact
interactions) mediators. Since the razor analysis requires multiple jets in the
final state, the data set is complementary to that used for the monojet search
and thus the bounds can be combined.Comment: 25 pages, 10 figures; v2 published version; v3 removes duplication of
manuscript in pd
Tevatron Run II combination of the effective leptonic electroweak mixing angle
Get PDFThe Ministry of Science and Innovation and the Consolider-Ingenio 2010 Program and the European Union community Marie Curie Fellowship Contract No. 302103.Aaltonen, T., Abazov, V.M., Abbott, B., Acharya, B.S., Adams, M., Adams, T., Agnew, J.P., Alexeev, G.D., Alkhazov, G., Alton, A., Amerio, S., Amidei, D., Anastassov, A., Annovi, A., Antos, J., Apollinari, G., Appel, J.A., Arisawa, T., Artikov, A., Asaadi, J., Ashmanskas, W., Askew, A., Atkins, S., Auerbach, B., Augsten, K., Aurisano, A., Aushev, V., Aushev, Y., Avila, C., Azfar, F., Badaud, F., Badgett, W., Bae, T., Bagby, L., Baldin, B., Bandurin, D.V., Banerjee, S., Barbaro-Galtieri, A., Barberis, E., Baringer, P., Barnes, V.E., Barnett, B.A., Barria, P., Bartlett, J.F., Bartos, P., Bassler, U., Bauce, M., Bazterra, V., Bean, A., Bedeschi, F., Begalli, M., Behari, S., Bellantoni, L., Bellettini, G., Bellinger, J., Benjamin, D., Beretvas, A., Beri, S.B., Bernardi, G., Bernhard, R., Bertram, I., Besançon, M., Beuselinck, R., Bhat, P.C., Bhatia, S., Bhatnagar, V., Bhatti, A., Bland, K.R., Blazey, G., Blessing, S., Bloom, K., Blumenfeld, B., Bocci, A., Bodek, A., Boehnlein, A., Boline, D., Boos, E.E., Borissov, G., Bortoletto, D., Borysova, M., Boudreau, J., Boveia, A., Brandt, A., Brandt, O., Brigliadori, L., Brochmann, M., Brock, R., Bromberg, C., Bross, A., Brown, D., Brucken, E., Bu, X.B., Budagov, J., Budd, H.S., Buehler, M., Buescher, V., Bunichev, V., Burdin, S., Burkett, K., Busetto, G., Bussey, P., Buszello, C.P., Butti, P., Buzatu, A., Calamba, A., Camacho-PĂ©rez, E., Camarda, S., Campanelli, M., Canelli, F., Carls, B., Carlsmith, D., Carosi, R., Carrillo, S., Casal, B., Casarsa, M., Casey, B.C.K., Castilla-Valdez, H., Castro, A., Catastini, P., Caughron, S., Cauz, D., Cavaliere, V., Cerri, A., Cerrito, L., Chakrabarti, S., Chan, K.M., Chandra, A., Chapon, E., Chen, G., Chen, Y.C., Chertok, M., Chiarelli, G., Chlachidze, G., Cho, K., Cho, S.W., Choi, S., Chokheli, D., Choudhary, B., Cihangir, S., Claes, D., Clark, A., Clarke, C., Clutter, J., Convery, M.E., Conway, J., Cooke, M., Cooper, W.E., Corbo, M., Corcoran, M., Cordelli, M., Couderc, F., Cousinou, M.-C., Cox, C.A., Cox, D.J., Cremonesi, M., Cruz, D., Cuevas, J., Culbertson, R., Cuth, J., Cutts, D., Das, A., D'Ascenzo, N., Datta, M., Davies, G., De Barbaro, P., De Jong, S.J., De La Cruz-Burelo, E., DĂ©liot, F., Demina, R., Demortier, L., Deninno, M., Denisov, D., Denisov, S.P., D'Errico, M., Desai, S., Deterre, C., Devaughan, K., Devoto, F., Di Canto, A., Di Ruzza, B., Diehl, H.T., Diesburg, M., Ding, P.F., Dittmann, J.R., Dominguez, A., Donati, S., D'Onofrio, M., Dorigo, M., Driutti, A., Drutskoy, A., Dubey, A., Dudko, L.V., Duperrin, A., Dutt, S., Eads, M., Ebina, K., Edgar, R., Edmunds, D., Elagin, A., Ellison, J., Elvira, V.D., Enari, Y., Erbacher, R., Errede, S., Esham, B., Evans, H., Evdokimov, A., Evdokimov, V.N., Farrington, S., FaurĂ©, A., Feng, L., Ferbel, T., FernĂĄndez Ramos, J.P., Fiedler, F., Field, R., Filthaut, F., Fisher, W., Fisk, H.E., Flanagan, G., Forrest, R., Fortner, M., Fox, H., Franc, J., Franklin, M., Freeman, J.C., Frisch, H., Fuess, S., Funakoshi, Y., Galloni, C., Garbincius, P.H., Garcia-Bellido, A., GarcĂa-GonzĂĄlez, J.A., Garfinkel, A.F., Garosi, P., Gavrilov, V., Geng, W., Gerber, C.E., Gerberich, H., Gerchtein, E., Gershtein, Y., Giagu, S., Giakoumopoulou, V., Gibson, K., Ginsburg, C.M., Ginther, G., Giokaris, N., Giromini, P., Glagolev, V., Glenzinski, D., Gogota, O., Gold, M., Goldin, D., Golossanov, A., Golovanov, G., Gomez, G., Gomez-Ceballos, G., Goncharov, M., GonzĂĄlez LĂłpez, O., Gorelov, I., Goshaw, A.T., Goulianos, K., Gramellini, E., Grannis, P.D., Greder, S., Greenlee, H., Grenier, G., Gris, P., Grivaz, J.-F., Grohsjean, A., Grosso-Pilcher, C., GrĂŒnendahl, S., GrĂŒnewald, M.W., Guillemin, T., Guimaraes Da Costa, J., Gutierrez, G., Gutierrez, P., Hahn, S.R., Haley, J., Han, J.Y., Han, L., Happacher, F., Hara, K., Harder, K., Hare, M., Harel, A., Harr, R.F., Harrington-Taber, T., Hatakeyama, K., Hauptman, J.M., Hays, C., Hays, J., Head, T., Hebbeker, T., Hedin, D., Hegab, H., Heinrich, J., Heinson, A.P., Heintz, U., Hensel, C., Heredia-De La Cruz, I., Herndon, M., Herner, K., Hesketh, G., Hildreth, M.D., Hirosky, R., Hoang, T., Hobbs, J.D., Hocker, A., Hoeneisen, B., Hogan, J., Hohlfeld, M., Holzbauer, J.L., Hong, Z., Hopkins, W., Hou, S., Howley, I., Hubacek, Z., Hughes, R.E., Husemann, U., Hussein, M., Huston, J., Hynek, V., Iashvili, I., Ilchenko, Y., Illingworth, R., Introzzi, G., Iori, M., Ito, A.S., Ivanov, A., Jabeen, S., JaffrĂ©, M., James, E., Jang, D., Jayasinghe, A., Jayatilaka, B., Jeon, E.J., Jeong, M.S., Jesik, R., Jiang, P., Jindariani, S., Johns, K., Johnson, E., Johnson, M., Jonckheere, A., Jones, M., Jonsson, P., Joo, K.K., Joshi, J., Jun, S.Y., Jung, A.W., Junk, T.R., Juste, A., Kajfasz, E., Kambeitz, M., Kamon, T., Karchin, P.E., Karmanov, D., Kasmi, A., Kato, Y., Katsanos, I., Kaur, M., Kehoe, R., Kermiche, S., Ketchum, W., Keung, J., Khalatyan, N., Khanov, A., Kharchilava, A., Kharzheev, Y.N., Kilminster, B., Kim, D.H., Kim, H.S., Kim, J.E., Kim, M.J., Kim, S.H., Kim, S.B., Kim, Y.J., Kim, Y.K., Kimura, N., Kirby, M., Kiselevich, I., Kohli, J.M., Kondo, K., Kong, D.J., Konigsberg, J., Kotwal, A.V., Kozelov, A.V., Kraus, J., Kreps, M., Kroll, J., Kruse, M., Kuhr, T., Kumar, A., Kupco, A., Kurata, M., KurÄa, T., Kuzmin, V.A., Laasanen, A.T., Lammel, S., Lammers, S., Lancaster, M., Lannon, K., Latino, G., Lebrun, P., Lee, H.S., Lee, H.S., Lee, J.S., Lee, S.W., Lee, W.M., Lei, X., Lellouch, J., Leo, S., Leone, S., Lewis, J.D., Li, D., Li, H., Li, L., Li, Q.Z., Lim, J.K., Limosani, A., Lincoln, D., Linnemann, J., Lipaev, V.V., Lipeles, E., Lipton, R., Lister, A., Liu, H., Liu, Q., Liu, T., Liu, Y., Lobodenko, A., Lockwitz, S., Loginov, A., Lokajicek, M., Lopes De Sa, R., Lucchesi, D., LucĂ , A., Lueck, J., Lujan, P., Lukens, P., Luna-Garcia, R., Lungu, G., Lyon, A.L., Lys, J., Lysak, R., MacIel, A.K.A., Madar, R., Madrak, R., Maestro, P., Magaña-Villalba, R., Malik, S., Malik, S., Malyshev, V.L., Manca, G., Manousakis-Katsikakis, A., Mansour, J., Marchese, L., Margaroli, F., Marino, P., MartĂnez-Ortega, J., Matera, K., Mattson, M.E., Mazzacane, A., Mazzanti, P., McCarthy, R., McGivern, C.L., McNulty, R., Mehta, A., Mehtala, P., Meijer, M.M., Melnitchouk, A., Menezes, D., Mercadante, P.G., Merkin, M., Mesropian, C., Meyer, A., Meyer, J., Miao, T., Miconi, F., Mietlicki, D., Mitra, A., Miyake, H., Moed, S., Moggi, N., Mondal, N.K., Moon, C.S., Moore, R., Morello, M.J., Mukherjee, A., Mulhearn, M., Muller, T., Murat, P., Mussini, M., Nachtman, J., Nagai, Y., Naganoma, J., Nagy, E., Nakano, I., Napier, A., Narain, M., Nayyar, R., Neal, H.A., Negret, J.P., Nett, J., Neustroev, P., Nguyen, H.T., Nigmanov, T., Nodulman, L., Noh, S.Y., Norniella, O., Nunnemann, T., Oakes, L., Oh, S.H., Oh, Y.D., Okusawa, T., Orava, R., Orduna, J., Ortolan, L., Osman, N., Pagliarone, C., Pal, A., Palencia, E., Palni, P., Papadimitriou, V., Parashar, N., Parihar, V., Park, S.K., Parker, W., Partridge, R., Parua, N., Patwa, A., Pauletta, G., Paulini, M., Paus, C., Penning, B., Perfilov, M., Peters, Y., Petridis, K., Petrillo, G., PĂ©troff, P., Phillips, T.J., Piacentino, G., Pianori, E., Pilot, J., Pitts, K., Plager, C., Pleier, M.-A., Podstavkov, V.M., Pondrom, L., Popov, A.V., Poprocki, S., Potamianos, K., Pranko, A., Prewitt, M., Price, D., Prokopenko, N., Prokoshin, F., Ptohos, F., Punzi, G., Qian, J., Quadt, A., Quinn, B., Ratoff, P.N., Razumov, I., Redondo FernĂĄndez, I., Renton, P., Rescigno, M., Rimondi, F., Ripp-Baudot, I., Ristori, L., Rizatdinova, F., Robson, A., Rodriguez, T., Rolli, S., Rominsky, M., Ronzani, M., Roser, R., Rosner, J.L., Ross, A., Royon, C., Rubinov, P., Ruchti, R., Ruffini, F., Ruiz, A., Russ, J., Rusu, V., Sajot, G., Sakumoto, W.K., Sakurai, Y., SĂĄnchez-HernĂĄndez, A., Sanders, M.P., Santi, L., Santos, A.S., Sato, K., Savage, G., Saveliev, V., 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T., Yatsunenko, Y.A., Ye, W., Ye, Z., Yeh, G.P., Yi, K., Yin, H., Yip, K., Yoh, J., Yorita, K., Yoshida, T., Youn, S.W., Yu, G.B., Yu, I., Yu, J.M., Zanetti, A.M., Zeng, Y., Zennamo, J., Zhao, T.G., Zhou, B., Zhou, C., Zhu, J., Zielinski, M., Zieminska, D., Zivkovic, L., Zucchelli, S., CDF Collaboratio
A Fast Track towards the `Higgs' Spin and Parity
Get PDFThe LHC experiments ATLAS and CMS have discovered a new boson that resembles
the long-sought Higgs boson: it cannot have spin one, and has couplings to
other particles that increase with their masses, but the spin and parity remain
to be determined. We show here that the `Higgs' + gauge boson invariant-mass
distribution in `Higgs'-strahlung events at the Tevatron or the LHC would be
very different under the J^P = 0+, 0- and 2+ hypotheses, and could provide a
fast-track indicator of the `Higgs' spin and parity. Our analysis is based on
simulations of the experimental event selections and cuts using PYTHIA and
Delphes, and incorporates statistical samples of `toy' experiments.Comment: 18 pages, 9 pdf figure
Matching Tree-Level Matrix Elements with Interleaved Showers
Get PDFWe present an implementation of the so-called CKKW-L merging scheme for
combining multi-jet tree-level matrix elements with parton showers. The
implementation uses the transverse-momentum-ordered shower with interleaved
multiple interactions as implemented in PYTHIA8. We validate our procedure
using e+e--annihilation into jets and vector boson production in hadronic
collisions, with special attention to details in the algorithm which are
formally sub-leading in character, but may have visible effects in some
observables. We find substantial merging scale dependencies induced by the
enforced rapidity ordering in the default PYTHIA8 shower. If this rapidity
ordering is removed the merging scale dependence is almost negligible. We then
also find that the shower does a surprisingly good job of describing the
hardness of multi-jet events, as long as the hardest couple of jets are given
by the matrix elements. The effects of using interleaved multiple interactions
as compared to more simplistic ways of adding underlying-event effects in
vector boson production are shown to be negligible except in a few sensitive
observables. To illustrate the generality of our implementation, we also give
some example results from di-boson production and pure QCD jet production in
hadronic collisions.Comment: 44 pages, 23 figures, as published in JHEP, including all changes
recommended by the refere
Probing Top Anomalous Couplings at the Tevatron and the Large Hadron Collider
Full text linkChromomagnetic and chromoelectric dipole interactions of the top quark are
studied in a model independent framework. Limits are set on the scale of new
physics that might lead to such contributions using available Tevatron data.
Prospects at the LHC are reviewed.Comment: Version published in Praman
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