Is there a scientific book summarizing the orthodox buddhism, the most ancient form of it? I found many personal book about Buddhism; witnessing; life story; spiritual encounter, experiences, meditation. I never found however a book that explain and summarize the classical Buddhism : a consensus clear that none Buddhist can read to understand that philosophy better.
Science is really the Scientific Method. 

The Scientific Method is:

Observations

Hypotheses

Predictions

Experiments

Analysis

As a Zen Buddhist, specifically Vietnamese Engaged Buddhism here is what I see.

Most all of the studies (book, dharma talks, dharma sharing, sutra) have the elements listed above. A typical dharma talk (whether oral or written into a book) discusses observations. These observations lead to "insight" or a hypothesis/predictions about the true nature of reality/the mind/etc. Every dharma talk I have ever heard in zen has always asked us to take these insights and test them. Apply them in your life and see the outcome for yourself. I am not just told theories but asked to practice them. This is the Experiments phase. Then I am always asked to examine the practice to see the fruits of my effort. This is Analysis.

So basically I find that Zen Buddhism follows the scientific method quite perfectly. Thus I would say any Zen text could be considered a scientific text by the standards of the scientific method.

Now of course you are asking for a single book that "none Buddhist can read to understand that philosophy better". As a Zen Buddhist, this is pretty all-encompassing of Zen Buddhism: The Heart of the Buddha's Teaching by Thich Nhat Hanh. I read this book with non-buddhist weekly, as well as read this book with monastics. The approach in this book follows the methods I described above and is written in a way that is very approachable regardless of your skill level in the practice. 

Here is the Table of Contents of the Book so you can see what is all covered.

Part One The Four Noble Truths

Chapter One Entering the Heart of the Buddha

Chapter Two The First Dharma Talk

Chapter Three The Four Noble Truths

Chapter Four Understanding the Buddha's Teachings

Chapter FiveIs Everything Suffering?

Chapter Six Stopping, Calming, Resting, Healing

Chapter Seven Touching Our Suffering

Chapter Eight Realizing Well-Being

Part Two The Noble Eightfold Path

Chapter Nine Right View

Chapter Ten Right Thinking

Chapter Eleven Right Mindfulness

Chapter Twelve Right Speech

Chapter Thirteen Right Action

Chapter Fourteen Right Diligence

Chapter Fifteen Right Concentration

Chapter Sixteen Right Livelihood

Part Three Other Basic Buddhist Teachings

Chapter Seventeen The Two Truths

Chapter Eighteen The Three Dharma Seals

Chapter Nineteen The Three Doors of Liberation

Chapter Twenty The Three Bodies of Buddha

Chapter Twenty-One The Three Jewels

Chapter Twenty-Two The Four Immeasurable Minds

Chapter Twenty-Three The Five Aggregates

Chapter Twenty-Four The Five Powers

Chapter Twenty-Five The Six Paramitas

Chapter Twenty-Six The Seven Factors ofAwakening

Chapter Twenty-Seven The Twelve Links of Interdependent Co-Arising

Chapter Twenty-Eight Touching the Buddha Within