I would like to imagine how would physics look in a Universe governed by Standard model, sans Higgs. IOW: how would the unbroken SU(2)*U(1) be different from our usual broken one? Matt Strassler has a similar article here: https://profmattstrassler.com/artic...known-particles-if-the-higgs-field-were-zero/ (It's a bit different - he retains Higgs field, but posits that it's VEV is zero.) I'll describe how I understand things would be in such a case. Please correct me whereever I'm wrong. There is no "usual" electromagnetism in such a Universe. Instead, there are two new forces, SU(2) weak isospin and U(1) weak hypercharge. (I'll be skipping word "weak" from now on). All elementary particles are massless. Left- and right- fermions are different particles. The antiparticle of a left-fermion is a right-antifermion. Unbroken SU(2) is in some ways analogous to the familiar color SU(3) in our Universe: * there are three W massless bosons corresponding to generators of SU(2) * left-fermions are affected by isospin force - they form isospin doublets (similar to how quarks form color triplets). Namely, (e-left,ve-left) is one such doublet. (u-left,d-left) is another. * there are two "isospin charges" (similar to three colors of quarks). I'll call them "up-charge" and "down-charge". They are NOT similar to +- electric charges! e-left has -1 up-charge, but positron-right, the antiparticle of e-left, has -1 anti-up-charge, NOT +1 up-charge. * right-fermions have isospin charge 0. In essense, in this Universe leptons and W bosons would act as "two-color quarks and three-color gluons". Will this SU(2) interaction exhibit asymptotical freedom? Will there be confinement? Will leptons form two-particle "leptohadrons"? Also, in this Universe, left quarks are also isospin-charged, and will feel the effect of isospin force. This is going to make hadrons much more complicated. Right-fermions have zero isospin-charge and are not affected by isospin force. For instance, u-right and d-right quarks would probably still form "protons" and "neutrons", but they will have the same mass. Unbroken U(1) works a lot like electromagnetism, but with a stronger coupling constant. (By how much stronger?) Force carrier is the B boson, similar to photons we know. Most fermions are affected by this force. They have a hypercharge, similar to electric charge: Left-leptons (yes, including left-neutrinos!) have -1 hypercharge. Left-quarks are +1/3. Right-up-leptons (electrons et al) are −2. Right-up-quarks are +4/3. Right-down-quarks are −2/3. (If right-down-leptons (IOW, right-neutrinos) exist, they are the only particles with hypercharge 0). Note that for left-fermions, hypercharge does not depend on up/down-ness. This is another manifestation of the fact that, say, (e-left,ve-left) is more like one particle, not two - similar to how we usually talk about "u-quark" as one particle, not three differently colored quarks. Hadrons would be much different. u-right and d-right quarks would probably still form "protons" and "neutrons", but they will have the same mass. This mass will be lower than our usual protons and neutrons, since quarks are massless. But u-left and d-left quarks should be unable to form a nucleon-like composite particle - while they can be color-neutral, three isospin-charged particles can't be isospin-neutral, and "isospin-confinement" prohibits this! So, either one of the quarks needs to be a right-quark; or this "left-nucleon" needs to pair with another "left-nucleon" to achieve isospin-neutral state. Mesons, on the other hand, can be formed out of left (anti)quarks. There will be more varieties of both hadrons and mesons, because (u-left,anti-d-right) "pion" is different from (u-right,anti-d-left) one. Binding energies will be different because left-quarks are also affected by isospin interaction, which should be attractive (about 1/2 strength of color force?). Thus, it's likely during baryogenesis only the least-energetic hadron states will survive. What those will be? left+left+right? left-leptons would probably form two-particle "leptohadrons", bound by isospin interaction. For example, (e-left,ve-left) pair is an analog of three-quark hadron. (e-left,anti-e-right) is an analog of pion0 (and it's also the usual positronium). Hadrons and leptohadrons will have mass due to gluons and W bosons bouncing inside, just like hadrons get most of their mass from gluons in our Universe. (u-left,d-left,d-right) hadron would have hypercharge +1/3 +1/3 -2/3 = 0 (u-left,d-left,u-right) hadron would have hypercharge +1/3 +1/3 +4/3 = +2 (e-left,ve-left) leptohadron would have hypercharge -1 -1 = -2 These two last composite particles can form a hypercharge-neutral "hydrogen atom". It seems that 2nd and 3rd generation of leptons and quarks will be indistinguishable from the 1st - they are all massless, and have the same charges. IOW: generations would be unobservable, there will be just one generation?