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WIMPonium and Boost Factors for Indirect Dark Matter Detection

Phys.Lett.B676:133-139,2009 (2008)

Authors:

J March-Russell, SM West

Abstract:

We argue that WIMP dark matter can annihilate via long-lived "WIMPonium" bound states in reasonable particle physics models of dark matter (DM). WIMPonium bound states can occur at or near threshold leading to substantial enhancements in the DM annihilation rate, closely related to the Sommerfeld effect. Large "boost factor" amplifications in the annihilation rate can thus occur without large density enhancements, possibly preferring colder less dense objects such as dwarf galaxies as locations for indirect DM searches. The radiative capture to and transitions among the WIMPonium states generically lead to a rich energy spectrum of annihilation products, with many distinct lines possible in the case of 2-body decays to $\gamma\gamma$ or $\gamma Z$ final states. The existence of multiple radiative capture modes further enhances the total annihilation rate, and the detection of the lines would give direct over-determined information on the nature and self-interactions of the DM particles.
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WIMPonium and Boost Factors for Indirect Dark Matter Detection

(2008)

Authors:

John March-Russell, Stephen M West
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First measurement of the fraction of top-quark pair production through gluon-gluon fusion

Physical Review D - Particles, Fields, Gravitation and Cosmology 78:11 (2008)

Authors:

T Aaltonen, J Adelman, T Akimoto, MG Albrow, B Álvarez González, S Amerio, D Amidei, A Anastassov, A Annovi, J Antos, M Aoki, G Apollinari, A Apresyan, T Arisawa, A Artikov, W Ashmanskas, A Attal, A Aurisano, F Azfar, P Azzi-Bacchetta, P Azzurri, N Bacchetta, W Badgett, A Barbaro-Galtieri, VE Barnes, BA Barnett, S Baroiant, V Bartsch, G Bauer, PH Beauchemin, F Bedeschi, P Bednar, S Behari, G Bellettini, J Bellinger, A Belloni, D Benjamin, A Beretvas, J Beringer, T Berry, A Bhatti, M Binkley, D Bisello, I Bizjak, RE Blair, C Blocker, B Blumenfeld, A Bocci, A Bodek, V Boisvert, G Bolla, A Bolshov, D Bortoletto, J Boudreau, A Boveia, B Brau, A Bridgeman, L Brigliadori, C Bromberg, E Brubaker, J Budagov, HS Budd, S Budd, K Burkett, G Busetto, P Bussey, A Buzatu, KL Byrum, S Cabrera, M Campanelli, M Campbell, F Canelli, A Canepa, D Carlsmith, R Carosi, S Carrillo, S Carron, B Casal, M Casarsa, A Castro, P Catastini, D Cauz, M Cavalli-Sforza, A Cerri, L Cerrito, SH Chang, YC Chen, M Chertok, G Chiarelli, G Chlachidze, F Chlebana, K Cho, D Chokheli, JP Chou, G Choudalakis, SH Chuang, K Chung, WH Chung, YS Chung, CI Ciobanu

Abstract:

We present the first measurement of σ(gg→tt̄)/ σ(pp̄→tt̄). We use 0.96fb-1 of s=1.96TeV pp̄ collision data recorded with the CDF II detector at Fermilab. Using charged particles with low transverse momentum in tt̄ events, we find σ(gg→ tt̄)/σ(pp̄→tt̄)=0.07±0.14(stat)±0. 07(syst), corresponding to a 95% confidence level upper limit of 0.33, in agreement with the standard model next-to-leading-order prediction of 0.15±0.05. © 2008 The American Physical Society.
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Two-photon widths of the χcJ states of charmonium

Physical Review D - Particles, Fields, Gravitation and Cosmology 78:9 (2008)

Authors:

KM Ecklund, W Love, V Savinov, A Lopez, H Mendez, J Ramirez, JY Ge, DH Miller, IPJ Shipsey, B Xin, GS Adams, M Anderson, JP Cummings, I Danko, D Hu, B Moziak, J Napolitano, Q He, J Insler, H Muramatsu, CS Park, EH Thorndike, F Yang, M Artuso, S Blusk, S Khalil, J Li, R Mountain, S Nisar, K Randrianarivony, N Sultana, T Skwarnicki, S Stone, JC Wang, LM Zhang, G Bonvicini, D Cinabro, M Dubrovin, A Lincoln, P Naik, J Rademacker, DM Asner, KW Edwards, J Reed, RA Briere, T Ferguson, G Tatishvili, H Vogel, ME Watkins, JL Rosner, JP Alexander, DG Cassel, JE Duboscq, R Ehrlich, L Fields, RS Galik, L Gibbons, R Gray, SW Gray, DL Hartill, D Hertz, JM Hunt, J Kandaswamy, DL Kreinick, VE Kuznetsov, J Ledoux, H Mahlke-Krüger, D Mohapatra, PUE Onyisi, JR Patterson, D Peterson, D Riley, A Ryd, AJ Sadoff, X Shi, S Stroiney, WM Sun, T Wilksen, SB Athar, R Patel, J Yelton, P Rubin, BI Eisenstein, I Karliner, S Mehrabyan, N Lowrey, M Selen, EJ White, J Wiss, RE Mitchell, MR Shepherd, D Besson, TK Pedlar, D Cronin-Hennessy, KY Gao, J Hietala, Y Kubota, T Klein, BW Lang, R Poling

Abstract:

Using a data sample of 24.5×106 ψ(2S) the reactions ψ(2S)→γχcJ, χcJ→γγ have been studied for the first time to determine the two-photon widths of the χcJ states of charmonium in their decay into two photons. The measured quantities are B(ψ(2S)→γχc0)×B(χc0→γγ)=(2. 17±0.32±0.10)×10-5 and B(ψ(2S)→γχc2) ×B(χc2→γγ)=(2.68±0.28±0.15)×10-5. Using values for B(ψ(2S)→γχc0,c2) and Γ(χc0,c2) from the literature the two-photon widths are derived to be Γγ γ(χc0)=(2.36±0.35±0.22)keV, Γγγ(χ c2)=(0.66±0.07±0.06)keV, and R≡Γγγ(χ c2)/Γγγ(χc0)=0.278±0.050±0.036. The importance of the measurement of R is emphasized. For the forbidden transition, χc1→γγ, an upper limit of Γγγ(χc1) <0.03keV is established. © 2008 The American Physical Society.
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Measurement of the kT Distribution of Particles in Jets Produced in ppbar Collisions at s**(1/2)=1.96$-TeV

ArXiv 0811.2820 (2008)

Authors:

CDF Collaboration, T Aaltonen
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