Search for the Rare Decay KL --> pi0 ee

The KTeV/E799 experiment at Fermilab has searched for the rare kaon decay KL--> pi0ee. This mode is expected to have a significant CP violating component. The measurement of its branching ratio could support the Standard Model or could indicate the existence of new physics. This letter reports new results from the 1999-2000 data set. One event is observed with an expected background at 0.99 +/- 0.35 events. We set a limit on the branching ratio of 3.5 x 10^(-10) at the 90% confidence level. Combining the results with the dataset taken in 1997 yields the final KTeV result: BR(KL --> pi0 ee) < 2.8 x 10^(-10) at 90% CL.Comment: 4 pages, three figure

On the selection of AGN neutrino source candidates for a source stacking analysis with neutrino telescopes

The sensitivity of a search for sources of TeV neutrinos can be improved by grouping potential sources together into generic classes in a procedure that is known as source stacking. In this paper, we define catalogs of Active Galactic Nuclei (AGN) and use them to perform a source stacking analysis. The grouping of AGN into classes is done in two steps: first, AGN classes are defined, then, sources to be stacked are selected assuming that a potential neutrino flux is linearly correlated with the photon luminosity in a certain energy band (radio, IR, optical, keV, GeV, TeV). Lacking any secure detailed knowledge on neutrino production in AGN, this correlation is motivated by hadronic AGN models, as briefly reviewed in this paper. The source stacking search for neutrinos from generic AGN classes is illustrated using the data collected by the AMANDA-II high energy neutrino detector during the year 2000. No significant excess for any of the suggested groups was found.Comment: 43 pages, 12 figures, accepted by Astroparticle Physic

All-particle cosmic ray energy spectrum measured with 26 IceTop stations

We report on a measurement of the cosmic ray energy spectrum with the IceTop air shower array, the surface component of the IceCube Neutrino Observatory at the South Pole. The data used in this analysis were taken between June and October, 2007, with 26 surface stations operational at that time, corresponding to about one third of the final array. The fiducial area used in this analysis was 0.122 km^2. The analysis investigated the energy spectrum from 1 to 100 PeV measured for three different zenith angle ranges between 0{\deg} and 46{\deg}. Because of the isotropy of cosmic rays in this energy range the spectra from all zenith angle intervals have to agree. The cosmic-ray energy spectrum was determined under different assumptions on the primary mass composition. Good agreement of spectra in the three zenith angle ranges was found for the assumption of pure proton and a simple two-component model. For zenith angles {\theta} < 30{\deg}, where the mass dependence is smallest, the knee in the cosmic ray energy spectrum was observed between 3.5 and 4.32 PeV, depending on composition assumption. Spectral indices above the knee range from -3.08 to -3.11 depending on primary mass composition assumption. Moreover, an indication of a flattening of the spectrum above 22 PeV were observed.Comment: 38 pages, 17 figure

An improved method for measuring muon energy using the truncated mean of dE/dx

The measurement of muon energy is critical for many analyses in large Cherenkov detectors, particularly those that involve separating extraterrestrial neutrinos from the atmospheric neutrino background. Muon energy has traditionally been determined by measuring the specific energy loss (dE/dx) along the muon's path and relating the dE/dx to the muon energy. Because high-energy muons (E_mu > 1 TeV) lose energy randomly, the spread in dE/dx values is quite large, leading to a typical energy resolution of 0.29 in log10(E_mu) for a muon observed over a 1 km path length in the IceCube detector. In this paper, we present an improved method that uses a truncated mean and other techniques to determine the muon energy. The muon track is divided into separate segments with individual dE/dx values. The elimination of segments with the highest dE/dx results in an overall dE/dx that is more closely correlated to the muon energy. This method results in an energy resolution of 0.22 in log10(E_mu), which gives a 26% improvement. This technique is applicable to any large water or ice detector and potentially to large scintillator or liquid argon detectors.Comment: 12 pages, 16 figure

Measurements Of The Decay Kl → E+e-μ+μ-

Several 132 KL → e+e- μ+ μ- events were observed from the 1997 and 1999 runs of the KTeV experiments, with an estimated background of 0.8 events. In the first measurement of the parameter α using this decay mode, it was found that α=-1.59±0.37. No evidence was found for CP-violating contributions to the KLγ*γ* interaction.9014141801/1141801/5Wolfenstein, L., (1983) Phys. Rev. Lett., 51, p. 1945Belanger, G., Geng, C.Q., (1991) Phys. Rev. D, 43, p. 140Buras, A.J., Fleischer, R., (1998) Advanced Ser. Direct. High Energy Phys., 15, p. 65Uy, Z.E.S., (1991) Phys. Rev. D, 43, p. 802D'Ambrosio, G., Isidori, G., Portolès, J., (1998) Phys. Lett. B, 423, p. 385Alavi-Harati, A., (2001) Phys. Rev. Lett., 87, p. 71801. , KTeV CollaborationAlavi-Harati, A., (2001) Phys. Rev. Lett., 86, p. 5425. , KTeV CollaborationUy, Z.E.S., (2002) Eur. Phys. J. C, 23, p. 113Alavi-Harati, A., (2001) Phys. Rev. Lett., 87, p. 111802. , KTeV CollaborationHamm, J.C., (2002), Ph.D. thesis, The University of Arizona(Fermilab Report No. fERMILAB-THESIS-2002-09)Alavi-Harati, A., (1999) Phys. Rev. Lett., 83, p. 922. , KTeV CollaborationAlavi-Harati, A., (2000) Phys. Rev. D, 61, p. 072006. , KTeV CollaborationBrown, C., (1996) Nucl. Instrum. Methods Phys. Res., Sect. A, 369, p. 248Quinn, G.B., (2000), Ph.D. thesis, The University of ChicagoBarker, A.R., Huang, H., Toale, P.A., Engle, J., hep-ph/0210174Bergström, L., Massó, E., Singer, P., (1983) Phys. Lett., 131 B, p. 229Fanti, V., (1999) Phys. Lett. B, 458, p. 553. , NA48 Collaboratio

Milagro limits and HAWC sensitivity for the rate-density of evaporating Primordial Black Holes

postprin

On the sensitivity of the HAWC observatory to gamma-ray bursts

We present the sensitivity of HAWC to Gamma Ray Bursts (GRBs). HAWC is a very high-energy gamma-ray observatory currently under construction in Mexico at an altitude of 4100 m. It will observe atmospheric air showers via the water Cherenkov method. HAWC will consist of 300 large water tanks instrumented with 4 photomultipliers each. HAWC has two data acquisition (DAQ) systems. The main DAQ system reads out coincident signals in the tanks and reconstructs the direction and energy of individual atmospheric showers. The scaler DAQ counts the hits in each photomultiplier tube (PMT) in the detector and searches for a statistical excess over the noise of all PMTs. We show that HAWC has a realistic opportunity to observe the high-energy power law components of GRBs that extend at least up to 30 GeV, as it has been observed by Fermi LAT. The two DAQ systems have an energy threshold that is low enough to observe events similar to GRB 090510 and GRB 090902b with the characteristics observed by Fermi LAT. HAWC will provide information about the high-energy spectra of GRBs which in turn could help to understanding about e-pair attenuation in GRB jets, extragalactic background light absorption, as well as establishing the highest energy to which GRBs accelerate particles

Neutrino oscillation studies with IceCube-DeepCore

AbstractIceCube, a gigaton-scale neutrino detector located at the South Pole, was primarily designed to search for astrophysical neutrinos with energies of PeV and higher. This goal has been achieved with the detection of the highest energy neutrinos to date. At the other end of the energy spectrum, the DeepCore extension lowers the energy threshold of the detector to approximately 10 GeV and opens the door for oscillation studies using atmospheric neutrinos. An analysis of the disappearance of these neutrinos has been completed, with the results produced being complementary with dedicated oscillation experiments. Following a review of the detector principle and performance, the method used to make these calculations, as well as the results, is detailed. Finally, the future prospects of IceCube-DeepCore and the next generation of neutrino experiments at the South Pole (IceCube-Gen2, specifically the PINGU sub-detector) are briefly discussed

Final Results From The Ktev Experiment On The Decay Kl→π0γ γ

We report on a new measurement of the branching ratio B(KL→π 0γγ) using the KTeV detector. We reconstruct 1982 events with an estimated background of 608, that results in B(KL→π0γγ)=(1. 29±0.03stat±0.05syst)×10-6. We also measure the parameter, aV, which characterizes the strength of vector meson exchange terms in this decay. We find aV=-0.31±0.05stat±0.07syst. These results utilize the full KTeV data set collected from 1997 to 2000 and supersede earlier KTeV measurements of the branching ratio and aV. © 2008 The American Physical Society.7711Barr, G.D., (1990) Phys. Lett. B, 242, p. 523. , PYLBAJ 0370-2693 10.1016/0370-2693(90)91806-MPapadimitriou, V., (1991) Phys. Rev. D, 44, p. 573. , PRVDAQ 0556-2821 10.1103/PhysRevD.44.R573Barr, G.D., (1992) Phys. Lett. B, 284, p. 440. , PYLBAJ 0370-2693 10.1016/0370-2693(92)90458-GEcker, G., Pich, A., De Rafael, E., (1987) Phys. Lett. B, 189, p. 363. , PYLBAJ 0370-2693 10.1016/0370-2693(87)91448-1D'Ambrosio, G., Portoles, J., (1997) Nucl. Phys., 492, p. 417. , NUPBBO 0550-3213 10.1016/S0550-3213(97)00116-8Gabbiani, F., Valencia, G., (2002) Phys. Rev. D, 66, p. 074006. , PRVDAQ 0556-2821 10.1103/PhysRevD.66.074006Truong, T.N., (1993) Phys. Lett. B, 313, p. 221. , PYLBAJ 0370-2693 10.1016/0370-2693(93)91216-AAlavi-Harati, A., (2004) Phys. Rev. Lett., 93, p. 021805. , PRLTAO 0031-9007 10.1103/PhysRevLett.93.021805Alavi-Harati, A., (2000) Phys. Rev. Lett., 84, p. 5279. , PRLTAO 0031-9007 10.1103/PhysRevLett.84.5279Buchalla, G., D'Ambrosio, G., Isidori, G., (2003) Nucl. Phys., 672, p. 387. , NUPBBO 0550-3213 10.1016/j.nuclphysb.2003.09.010Mescia, F., Smith, C., Trine, S., J. High Energy Phys., 2006 (8), p. 88. , JHEPFG 1029-8479 10.1088/1126-6708/2006/08/088Batley, J.R., (2003) Phys. Lett. B, 576, p. 43. , PYLBAJ 0370-2693 10.1016/j.physletb.2003.10.001Alavi-Harati, A., (1999) Phys. Rev. Lett., 83, p. 917. , PRLTAO 0031-9007 10.1103/PhysRevLett.83.917Lai, A., (2002) Phys. Lett. B, 536, p. 229. , PYLBAJ 0370-2693 10.1016/S0370-2693(02)01863-4Alavi-Harati, A., (2003) Phys. Rev. D, 67, p. 012005. , PRVDAQ 0556-2821 10.1103/PhysRevD.67.012005Alavi-Harati, A., (2003) Phys. Rev. D, 67, p. 012005. , PRVDAQ 0556-2821 10.1103/PhysRevD.67.012005Bown, C., (1996) Nucl. Instrum. Methods Phys. Res., Sect. a, 369, p. 248. , NIMAER 0168-9002 10.1016/0168-9002(95)00799-7Brun, R., Carminati, F., W5013 (unpublished)Alexopoulos, T., (2004) Phys. Rev. D, 70, p. 092006. , PRVDAQ 0556-2821 10.1103/PhysRevD.70.092006Yao, W.-M., (2006) J. Phys. G, 33, p. 1. , JPGPED 0954-3899 10.1088/0954-3899/33/1/001http://www.aip.org/pubservs/epaps.html, See EPAPS Document No. E-PRVDAQ-77-071811 for tables of data and acceptance used in extracting aV. For more information on EPAPS, se

First Observation Of Kl→π±eνe+e-

This Letter is the first report of the KL→π±eνe+e- decay. Based on 19208±144 events, we determine the branching fraction, B(KL→π±eνe+e-;Me+e->5MeV/c2,Ee+e-*>30MeV)=(1. 285±0.041)×10-5, and Γ(Ke3ee;Me+e->5MeV/c2)/Γ(Ke3)= [4.57±0.04(stat)±0.14(syst)]×10-5. This ratio agrees with a theoretical prediction based on chiral perturbation theory (ChPT) calculated to O(p4). The measured kinematical distributions agree with those predicted by just ChPT O(p4), but show significant disagreement with ones predicted by leading-order ChPT. © 2007 The American Physical Society.998Fearing, H.W., Fischbach, E., Smith, J., (1970) Phys. Rev. D, 2, p. 542. , PRVDAQ 0556-2821 10.1103/PhysRevD.2.542Alavi-Harati, A., (2001) Phys. Rev. D, 64, p. 112004. , PRVDAQ 0556-2821 10.1103/PhysRevD.64.112004Alexopoulos, T., (2005) Phys. Rev. D, 71, p. 012001. , PRVDAQ 0556-2821 10.1103/PhysRevD.71.012001Gasser, J., Kubis, B., Paver, N., Verbeni, M., (2005) Eur. Phys. J. C, 40, p. 205. , EPCFFB 1434-6044 10.1140/epjc/s2005-02123-3Bijnens, S., Ecker, G., Gasser, J., (1994) The Second DAΦNE Physics Handbook, 125Tsuji, K., Sato, T., arXiv:0708.1576Kotera, K., (2006), Ph.D thesis, Osaka UniversityAlavi-Harati, A., (2003) Phys. Rev. D, 67, p. 012005. , PRVDAQ 0556-2821 10.1103/PhysRevD.67.012005Alavi-Harati, A., (2004) Phys. Rev. D, 70, pp. 079904E. , PRVDAQ 0556-2821 10.1103/PhysRevD.70.079904Barberio, E., Was, Z., (1994) Comput. Phys. Commun., 79, p. 291. , CPHCBZ 0010-4655 10.1016/0010-4655(94)90074-4Was, Z., Golonka, P., (2005) Nucl. Phys. B, Proc. Suppl., 144, p. 88. , NPBSE7 0920-5632 10.1016/j.nuclphysbps.2005.02.012Brun, R., (1994)Yao, W.-M., (2006) J. Phys. G, 33, p. 1. , JPGPED 0954-3899 10.1088/0954-3899/33/1/001Alexopoulos, T., (2004) Phys. Rev. Lett., 93, p. 181802. , PRLTAO 0031-9007 10.1103/PhysRevLett.93.181802Alexopoulos, T., (2004) Phys. Rev. D, 70, p. 092007. , PRVDAQ 0556-2821 10.1103/PhysRevD.70.09200