PARTICLE PHYSICS: With derivations complete at every step, computational demonstrations on the Texas Instruments TI-84 Plus CE Python, and no equation left unexplained

There is a species of textbook that treats its reader as a vessel to be filled, and another, rarer, that treats the reader as a colleague to be persuaded. This treatise aspires, with whatever success the reader will presently judge, to the second species. Particle physics is not a catalogue of facts about small things; it is an argument - long, occasionally acrimonious, and still unfinished - about what the world is made of and what it means to know it. A book that suppresses the argument in favour of its conclusions deprives the student of the very discipline it claims to teach. The reader I have in mind is curious and disciplined, in that order. Curiosity brings one to the door; discipline is what allows one to remain in the room when the mathematics arrives. I have tried to honour both. Nothing in this book falls from the sky: every equation is derived from what precedes it, every constant is traced to its measurement, and every claim of the form 'it can be shown' is followed, sometimes at inconvenient length, by the showing. Where a full derivation must wait for machinery developed in a later chapter, I say so explicitly, and I say where. The book proceeds from the empirical and conceptual foundations, through quantum mechanics, symmetry and quantum field theory, to the gauge theories, the Standard Model in its full particle content, the experimental apparatus that tests it, the physics that must lie beyond it, its cosmological setting, and finally the methods - symbolic, numerical, statistical and, yes, artificial - by which the subject now conducts itself. The itinerary is described in detail in Section 1.6, and a map of the whole territory precedes the table of contents. Numerical work is demonstrated throughout on the Texas Instruments TI-84 Plus CE Python, a modest machine whose very modesty is the point: if a calculation can be made transparent on a handheld calculator, it has been understood; if it cannot, one should be suspicious of one's understanding rather than of the calculator. Keystrokes are given in full, without omission, because there is no pedagogical virtue in a skipped step - only the appearance of one. I thank the students, colleagues and correspondents whose questions improved this book, and I accept sole custody of its errors, which I would be grateful to have reported. A treatise, like a proton, is best probed at high resolution. Porto and São Paulo, 2026