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Title: Light scalars and dark photons in Borexino and LSND experiments

Abstract

Bringing an external radioactive source close to a large underground detector can significantly advance sensitivity not only to sterile neutrinos but also to “dark” gauge bosons and scalars. Here we address in detail the sensitivity reach of the Borexino-SOX configuration, which will see a powerful (a few PBq) 144Ce– 144Pr source installed next to the Borexino detector, to light scalar particles coupled to the SM fermions. The mass reach of this configuration is limited by the energy release in the radioactive γ -cascade, which in this particular case is 2.2 MeV. Within that reach one year of operations will achieve an unprecedented sensitivity to coupling constants of such scalars, reaching down to g ~ 10 –7 levels and probing significant parts of parameter space not excluded by either beam dump constraints or astrophysical bounds. Should the current proton charge radius discrepancy be caused by the exchange of a MeV-mass scalar, then the simplest models will be decisively probed in this setup. In conclusion, we also update the beam dump constraints on light scalars and vectors, and in particular rule out dark photons with masses below 1 MeV, and couplings ϵ ≥ 10 –5.

Authors:
 [1]; ORCiD logo [2]
  1. Univ. of Victoria, Victoria, BC (Canada); Perimeter Institute for Theoretical Physics, Waterloo, ON (Canada)
  2. Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)
Publication Date:
Research Org.:
Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)
Sponsoring Org.:
USDOE Office of Science (SC), High Energy Physics (HEP) (SC-25)
OSTI Identifier:
1490854
Report Number(s):
arXiv:1706.00424; FERMILAB-PUB-17-689-A
Journal ID: ISSN 0370-2693; 1602481
Grant/Contract Number:  
AC02-07CH11359
Resource Type:
Accepted Manuscript
Journal Name:
Physics Letters. Section B
Additional Journal Information:
Journal Volume: 785; Journal Issue: C; Journal ID: ISSN 0370-2693
Publisher:
Elsevier
Country of Publication:
United States
Language:
English
Subject:
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS

Citation Formats

Pospelov, Maxim, and Tsai, Yu -Dai. Light scalars and dark photons in Borexino and LSND experiments. United States: N. p., 2018. Web. doi:10.1016/j.physletb.2018.08.053.
Pospelov, Maxim, & Tsai, Yu -Dai. Light scalars and dark photons in Borexino and LSND experiments. United States. doi:10.1016/j.physletb.2018.08.053.
Pospelov, Maxim, and Tsai, Yu -Dai. Fri . "Light scalars and dark photons in Borexino and LSND experiments". United States. doi:10.1016/j.physletb.2018.08.053. https://www.osti.gov/servlets/purl/1490854.
@article{osti_1490854,
title = {Light scalars and dark photons in Borexino and LSND experiments},
author = {Pospelov, Maxim and Tsai, Yu -Dai},
abstractNote = {Bringing an external radioactive source close to a large underground detector can significantly advance sensitivity not only to sterile neutrinos but also to “dark” gauge bosons and scalars. Here we address in detail the sensitivity reach of the Borexino-SOX configuration, which will see a powerful (a few PBq) 144Ce–144Pr source installed next to the Borexino detector, to light scalar particles coupled to the SM fermions. The mass reach of this configuration is limited by the energy release in the radioactive γ -cascade, which in this particular case is 2.2 MeV. Within that reach one year of operations will achieve an unprecedented sensitivity to coupling constants of such scalars, reaching down to g ~ 10–7 levels and probing significant parts of parameter space not excluded by either beam dump constraints or astrophysical bounds. Should the current proton charge radius discrepancy be caused by the exchange of a MeV-mass scalar, then the simplest models will be decisively probed in this setup. In conclusion, we also update the beam dump constraints on light scalars and vectors, and in particular rule out dark photons with masses below 1 MeV, and couplings ϵ ≥ 10–5.},
doi = {10.1016/j.physletb.2018.08.053},
journal = {Physics Letters. Section B},
number = C,
volume = 785,
place = {United States},
year = {2018},
month = {8}
}

Journal Article:
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Cited by: 8 works
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Figures / Tables:

Fig. 1 Fig. 1: Future sensitivity reach of the Borexino-SOX setup and existing constraints placed on the coupling constant-mass parameter space. We conduct the analysis in two fiducial radii, 2.00 m and 3.02 m, for the Borexino-SOX sensitivity reaches, in regard of the background from the 2.2 MeV n–p capture gamma raymore » discussed in section 3.3. Left panel: The gi ∝ mi scaling is assumed and ϵ is defined as ϵ2 = gpge/e2. Right panel: ge = gτ = 0, a gi ∝ mi scaling for μ and p, while ϵ2 = (me/mμ) × gpgμ/e2. The green curve is the parameter space that can explain the proton-size anomaly. The experimental reach (> 3σ ) by the Borexino-SOX setup is the blue regime. The recast of LSND constraints is shown in purple, while the gray area is constrained by the stellar energy loss. The solar production constraint is the protruding pink area between ϵ2 = 10−9 and 10−13. (For interpretation of the colors in the figure(s), the reader is referred to the web version of this article.)« less

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