- Email: [email protected]
Search for GUT monopoles at Super-Kamiokande
Available online at www.sciencedirect.com
Nuclear Physics B (Proc. Suppl.) 229–232 (2012) 540 www.elsevier.com/locate/npbps
Search for GUT monopoles at Super-Kamiokande K. Ueno, For the Super-Kamiokande Collaboration Kamioka Observatory, ICRR, Univ. of Tokyo, Higashi-Mozumi, Kamioka, Hida, Gifu 506-1205, Japan
Abstract GUT monopole-induced neutrinos from the Sun have been searched for using a 50000 ton water Cherenkov detector, Super-Kamiokande. The greatly improved limit on the monopole flux in the local universe is shown. Keywords: GUT monopole, neutrino, water Cherenkov detector
[1] K.Nakamura et al. (PDG), J. Phys. G 37 (2010) 075021 Email address: [email protected] (K. Ueno)
0920-5632/$ – see front matter © 2012 Elsevier B.V. All rights reserved. doi:10.1016/j.nuclphysbps.2012.09.177
10 10 10 10 10 10 10 10
-17 Mica
-18 -19 -20 -21 -22
e
10
Kolar Baksan Kamioka (Track Etch) MACRO (2002)
-16
-23 -24 -25
N
10
Soudan-2
K m am
10
UCSD II
-15 Parker Bound
Ka
10
-14
e
10
Preliminary
-26 -27
10
N
10
-13
ut ut io io ro ro k k rK n n St and and St am ar ar e- eIII I ( io (n (p 27 o io ka ( 3 n pi nd on 19 4 d co nd eco day ays en I/I nd s) ) sa I/I en te II s at ) (2 e 83 ) 5 da ys )
10
-12
Su pe
10
Flux upper limit (90% C.L.) (cm-2 s-1 sr-1)
It has been pointed out that copious low energy neutrinos could be emitted due to monopoles accumulating inside the Sun and catalyzing proton decay along their paths with cross sections typical of strong interactions via the so-called Callan-Rubakov process. In this scenario, protons decay into pions, and when these pions subsequently decay at rest, νe , νμ , and ν¯ μ with definite spectra are produced. After going through neutrino oscillation, all neutrino species appear when they arrive at the Earth and such low energy neutrino events can be detected by Super-Kamiokande. We searched for low energy (19 - 55 MeV) neutrinos from the Sun using both the inverse beta reaction of ν¯ e and electron scattering of all six types of neutrinos in the 22500 ton fiducial volume. We set an upper bound on the monopole flux: FM (σ0 /1mb) < 8.0 × 10−24 (βM /10−3 )2 cm−2 s−1 sr−1 (90% C.L.), where σ0 is the catalysis cross section and βM monopole velocity. Though we have not found any evidence for monopolecatalyzed proton decay, the obtained limit is much more stringent than the best cosmic-ray supermassive monopole flux limit: FM < 1.0 × 10−15 cm−2 s−1 sr−1 for 1.1 × 10−4 < βM < 0.1 [1]. Fig.1 shows several other limits on the monopole flux [2]–[12]; our muchimproved limit is at the bottom of the plot.
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10
-3
βM
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-1
1
Figure 1: 90% C.L. upper limits on the monopole flux as a function of monopole velocity, βM . Catalysis cross section, σ0 , is assumed. [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] [12]
J.L.Thron et al., Phys. Rev. D46 (1992) 484. A.M.Din et al., Phys. Lett. B 91 (1980) 77. E.N.Parker, Astrophys. J. 160 (1970) 383. E.N.Alexeyev et al., Nuovo Cimento 35 (1982) 413. H.Adarkar et al., Proc. ICRC 10 (1990) 95. S.Orito et al., Phys. Rev. Lett. 66 (1991) 1951. D.Ghosh and S.Chatterjea, Europhys. Lett. 12 (1990) 25. G.Giacomelli et al., Proc. ICHEP (2002) 129. E.W.Kolb and M.S.Turner, Astrophys.J. 286 (1984) 624. T.Kajita et al., JPSJ 54 (1985) 4065. A.Sakai, master thesis (1993)
Nuclear Physics B (Proc. Suppl.) 229–232 (2012) 540 www.elsevier.com/locate/npbps
Search for GUT monopoles at Super-Kamiokande K. Ueno, For the Super-Kamiokande Collaboration Kamioka Observatory, ICRR, Univ. of Tokyo, Higashi-Mozumi, Kamioka, Hida, Gifu 506-1205, Japan
Abstract GUT monopole-induced neutrinos from the Sun have been searched for using a 50000 ton water Cherenkov detector, Super-Kamiokande. The greatly improved limit on the monopole flux in the local universe is shown. Keywords: GUT monopole, neutrino, water Cherenkov detector
[1] K.Nakamura et al. (PDG), J. Phys. G 37 (2010) 075021 Email address: [email protected] (K. Ueno)
0920-5632/$ – see front matter © 2012 Elsevier B.V. All rights reserved. doi:10.1016/j.nuclphysbps.2012.09.177
10 10 10 10 10 10 10 10
-17 Mica
-18 -19 -20 -21 -22
e
10
Kolar Baksan Kamioka (Track Etch) MACRO (2002)
-16
-23 -24 -25
N
10
Soudan-2
K m am
10
UCSD II
-15 Parker Bound
Ka
10
-14
e
10
Preliminary
-26 -27
10
N
10
-13
ut ut io io ro ro k k rK n n St and and St am ar ar e- eIII I ( io (n (p 27 o io ka ( 3 n pi nd on 19 4 d co nd eco day ays en I/I nd s) ) sa I/I en te II s at ) (2 e 83 ) 5 da ys )
10
-12
Su pe
10
Flux upper limit (90% C.L.) (cm-2 s-1 sr-1)
It has been pointed out that copious low energy neutrinos could be emitted due to monopoles accumulating inside the Sun and catalyzing proton decay along their paths with cross sections typical of strong interactions via the so-called Callan-Rubakov process. In this scenario, protons decay into pions, and when these pions subsequently decay at rest, νe , νμ , and ν¯ μ with definite spectra are produced. After going through neutrino oscillation, all neutrino species appear when they arrive at the Earth and such low energy neutrino events can be detected by Super-Kamiokande. We searched for low energy (19 - 55 MeV) neutrinos from the Sun using both the inverse beta reaction of ν¯ e and electron scattering of all six types of neutrinos in the 22500 ton fiducial volume. We set an upper bound on the monopole flux: FM (σ0 /1mb) < 8.0 × 10−24 (βM /10−3 )2 cm−2 s−1 sr−1 (90% C.L.), where σ0 is the catalysis cross section and βM monopole velocity. Though we have not found any evidence for monopolecatalyzed proton decay, the obtained limit is much more stringent than the best cosmic-ray supermassive monopole flux limit: FM < 1.0 × 10−15 cm−2 s−1 sr−1 for 1.1 × 10−4 < βM < 0.1 [1]. Fig.1 shows several other limits on the monopole flux [2]–[12]; our muchimproved limit is at the bottom of the plot.
-5
10
-4
10
-3
βM
10
-2
10
-1
1
Figure 1: 90% C.L. upper limits on the monopole flux as a function of monopole velocity, βM . Catalysis cross section, σ0 , is assumed. [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] [12]
J.L.Thron et al., Phys. Rev. D46 (1992) 484. A.M.Din et al., Phys. Lett. B 91 (1980) 77. E.N.Parker, Astrophys. J. 160 (1970) 383. E.N.Alexeyev et al., Nuovo Cimento 35 (1982) 413. H.Adarkar et al., Proc. ICRC 10 (1990) 95. S.Orito et al., Phys. Rev. Lett. 66 (1991) 1951. D.Ghosh and S.Chatterjea, Europhys. Lett. 12 (1990) 25. G.Giacomelli et al., Proc. ICHEP (2002) 129. E.W.Kolb and M.S.Turner, Astrophys.J. 286 (1984) 624. T.Kajita et al., JPSJ 54 (1985) 4065. A.Sakai, master thesis (1993)