Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Constraint on the branching ratio of B_c \to tau nu from LEP1 and
  consequences for R(D(*)) anomaly   Recently there has been interest in the correlation between R(D*) and the
branching ratio (BR) of $B_c \to \tau \nu$ in models with a charged scalar
H^\pm. Any enhancement of R(D*) by $H^\pm$ alone (in order to agree with
current data) also enhances $BR(B_c \to \tau \nu$), for which there has been no
direct search at hadron colliders. We show that LEP data taken at the Z peak
requires BR($B_c \to \tau \nu$) < 10%, and this constraint is significantly
stronger than the recent constraint BR($B_c \to \tau \nu$) < 30% from
considering the lifetime of B_c. In order to respect this new constraint, any
explanation of the R(D) and R(D*) anomaly in terms of $H^\pm$ alone would
require the future measurements of R(D*) to be even closer to the Standard
Model prediction. A stronger limit on BR($B_c \to \tau \nu$) (or its first
measurement) would be obtained if the L3 collaboration used all its data taken
at the Z peak.

28
The categories of this paper are: alg-geom
31
The categories of this paper are: ao-sci
8
The categories of this paper are: hep-ex
1
The categories of this paper are: cs
29
The categories of this paper are: funct-an
13
The categories of this paper are: quant-ph
19
The categories of this paper are: eess
27
The categories of this paper are: comp-gas
35
The categories of this paper are: mtrl-th
9
The categories of this paper are: nlin
20
The categories of this paper are: acc-phys
24
The categories of this paper are: dg-ga
4
The categories of this paper are: cond-mat
10
The categories of this paper are: q-bio
37
The categories of this paper are: supr-con
5
The categories of this paper are: gr-qc