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Abstract
In this paper, making use of a new integral operator defined in the open unit disk we introduce and study a new class of simply connected convex domain of analytic and univalent functions. We derive some inclusion results and its geometric properties. Moreover, we discuss analytic criteria for a member of the simply connected convex domain to be a member of the class of functions with positive real part greater than μ.
2010 Mathematics Subject Classification:
1. Introduction
We study simply connected domain including starlike and convex domain in geometric function theory. Miller and Mocanu (cf. [Citation1]) not only enlarged the scope of a simply connected domain but also worked to spread out in the area. In recent years, more and more researchers are interested to study the simply connected domain including starlike and convex domain (cf. [Citation2–10]). They not only introduced certain new simply connected domain including starlike and convex domain but also used them for the study of geometric properties of analytic and univalent functions. We are motivated by the research works based on analytic and univalent functions (cf. [Citation11] and [Citation12]). The articles provided an idea to introduce new subclasses of analytic and univalent functions in the open unit disk.
The functions analytic and univalent in of the form (Equation1
(1)
(1) ) with
are said to form the class
.
(1)
(1) For
and
, let
(cf. [Citation13]) denote the class of analytic function
with positive real part such that
and satisfy the analytic criterion
(2)
(2) Moreover,
. For the classes
and
(cf.[Citation14].) Note that
, where
is the class of functions with positive real part greater than β and
is the class of functions with positive real part. We can write (Equation2
(2)
(2) ) in Riemann–Stieltjes sense as
(3)
(3) where
is a function with bounded variation on
such that
(4)
(4) By using (Equation2
(2)
(2) ), we deduce that
if and only if there exist
such that
(5)
(5)
2. Materials and methods
For f given by (Equation1(1)
(1) ),
and
, we introduce a new integral operator as follows:
(6)
(6) By using (Equation6
(6)
(6) ), for the function f given in (Equation1
(1)
(1) ), we get
(7)
(7) Further, a straightforward calculation reveals that many differential operators introduced in other papers are special cases of the differential operator defined by (Equation7
(7)
(7) ). By specializing the parameters β and γ, we obtain the following operators studied by various authors:
[Citation15];
[Citation16];
[Citation17];
[Citation18];
[Citation19];
[Citation20].
For and
, let
denote the class of functions f defined by (Equation1
(1)
(1) ) and satisfy
(8)
(8) The analytic function
, for
belongs to the class
.
Next, we introduce definitions which will be used in our main results.
Definition 1
Let H be the set of complex valued functions such that
is continuous in a domain
,
and
,
then
whenever
with
for real θ and
where
.
Definition 2
Let H be the set of complex valued functions such that
is continuous in a domain
,
and
,
then
whenever
with
for real θ and
where
.
Lemma 1
[Citation1] Let be analytic in
with
and
. If
and
. Then
and
where m is real number and
Lemma 2
[Citation21] Let ,
and
be a complex valued function satisfy the conditions:
is continuous in a domain
,
and
,
whenever
and
.
If is analytic in
such that
and
then
in
.
3. Results and discussion
Theorem 3.1
If the function f given by (Equation1(1)
(1) ) belongs to the class
, then
, where
Proof.
By using (Equation2(2)
(2) ), if
, then it must satisfy the condition given by (Equation5
(5)
(5) ). Let
(9)
(9) where
. By using (Equation9
(9)
(9) ) and (Equation7
(7)
(7) ), we get
this implies
By using (Equation2
(2)
(2) ), we can see
For
and
, we define
such that
Since first two conditions of Lemma 1.2. are obvious so we proceed for third condition as follows:
where
We concluded that
, ⇔ A=0, B<0 and C>0. Hence by using Lemma 2, we get
.
Theorem 3.2
If the function f given by (Equation1(1)
(1) ) belongs to the class
, then
, where
Proof.
By using (Equation2(2)
(2) ), if
implies satisfy the condition given by (Equation5
(5)
(5) ). We consider
(10)
(10) where
. By using (Equation10
(10)
(10) ) and (Equation7
(7)
(7) ), we have
this implies
By using (Equation2
(2)
(2) ) for i=1,2, we have
For
and
, we define
such that
Since first two conditions of Lemma 1.2. are obvious so we proceed for third condition as follows:
where
We concluded that
, ⇔ A=0, B<0 and C>0. Hence by using Lemma 2, we get
.
Theorem 3.3
Let and f belongs to
satisfy the following criterion:
and
Then
Proof.
Let
(11)
(11) Clearly
and
. By using (Equation11
(11)
(11) ) and (Equation7
(7)
(7) ), we get
(12)
(12) By using (Equation7
(7)
(7) ) and doing some calculation, we have
(13)
(13) After using (Equation12
(12)
(12) ) and (Equation13
(13)
(13) ) simultaneously, we get
(14)
(14) After applying the same steps on (Equation14
(14)
(14) ) and (Equation7
(7)
(7) ), we get
(15)
(15) We claim that
. On contrary, we suppose that for a=k=1, the
, this implies there exist
such that
, hence
and
, then
where
. After doing calculation, we have
and
This implies
Since
, then by using definition of
, we have
which is contradiction and hence
Theorem 3.4
Let and f belongs to
satisfy the following criterion:
and
Then
Proof.
Since,
(16)
(16) then clearly
and
. By using (Equation16
(16)
(16) ) and (Equation7
(7)
(7) ), we get
(17)
(17) By using (Equation7
(7)
(7) ) and doing some calculation, we have
(18)
(18) and
(19)
(19) Simultaneously using (Equation17
(17)
(17) ), (Equation18
(18)
(18) ) and (Equation19
(19)
(19) ) implies
or
(20)
(20)
After differentiating (Equation20(20)
(20) ) and simplification, we get
(21)
(21) Now by using (Equation7
(7)
(7) ) and (Equation20
(20)
(20) ) for right-hand side of (Equation21
(21)
(21) ), we get
We claim that
. On contrary, we suppose that for a=k=1,
, this implies there exist
such that
, hence
and
, then
. This implies that
where
. After doing calculation, we have
and
This implies
Since
, then by using definition of
, we have
which is contradiction and therefore
Example 1
Since we have
After taking n-times hadamard product of g, we have
We define
which clearly satisfy our result.
4. Conclusion
In this paper, an integral operator is used to introduce new simply connected convex domain of analytic functions in the open unit disk . Further, analytic criteria for p-valent analytic function belongs to simply connected convex domain to be a member of class of functions with positive real part greater than μ have been discussed.
Acknowledgements
The author is deeply indebted to the referees for providing constructive comments and helps in improving the content of this article.
Disclosure statement
No potential conflict of interest was reported by the author.
ORCID
M. I. Faisal http://orcid.org/0000-0002-4169-4366
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