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Title: Prospect for measuring the CP phase in the $$h\tau\tau$$ coupling at the LHC

The search for a new source of CP violation is one of the most important endeavors in particle physics. A particularly interesting way to perform this search is to probe the CP phase in the $$h\tau\tau$$ coupling, as the phase is currently completely unconstrained by all existing data. Recently, a novel variable $$\Theta$$ was proposed for measuring the CP phase in the $$h\tau\tau$$ coupling through the $$\tau^\pm \to \pi^\pm \pi^0 \nu$$ decay mode. We examine two crucial questions that the real LHC detectors must face, namely, the issue of neutrino reconstruction and the effects of finite detector resolution. For the former, we find strong evidence that the collinear approximation is the best for the $$\Theta$$ variable. For the latter, we find that the angular resolution is actually not an issue even though the reconstruction of $$\Theta$$ requires resolving the highly collimated $$\pi^\pm$$'s and $$\pi^0$$'s from the $$\tau$$ decays. Instead, we find that it is the missing transverse energy resolution that significantly limits the LHC reach for measuring the CP phase via $$\Theta$$.
Authors:
 [1] ;  [2] ;  [1] ;  [1] ;  [3]
  1. Florida State Univ., Tallahassee, FL (United States)
  2. Florida State Univ., Tallahassee, FL (United States); Syracuse Univ., NY (United States)
  3. Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States); Florida State Univ., Tallahassee, FL (United States)
Publication Date:
OSTI Identifier:
1178626
Report Number(s):
JLAB-THY--15-2000; DOE/OR/23177--3267; arXiv:1501.03156
Journal ID: ISSN 1550-7998; PRVDAQ; ArticleNumber: 075014; FG02-13ER41942; TRN: US1601140
Grant/Contract Number:
AC05-06OR23177
Type:
Accepted Manuscript
Journal Name:
Physical Review. D, Particles, Fields, Gravitation and Cosmology
Additional Journal Information:
Journal Volume: 91; Journal Issue: 7; Journal ID: ISSN 1550-7998
Publisher:
American Physical Society (APS)
Research Org:
Thomas Jefferson National Accelerator Facility, Newport News, VA (United States)
Sponsoring Org:
USDOE Office of Science (SC), Nuclear Physics (NP) (SC-26)
Country of Publication:
United States
Language:
English
Subject:
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; 46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY