Exotic particles carrying baryon number and with a mass of the order nucleon have been proposed for various reasons including baryogenesis, dark matter, mirror worlds, neutron lifetime puzzle. We show that existence stars greater than 0.7 M_{⊙} places severe constraints on such particles, requiring them to be heavier 1.2 GeV or strongly repulsive self-interactions.

We show how observations of gravitational waves from binary neutron star (BNS) mergers over the next few years can be combined with insights nuclear physics to obtain useful constraints on equation state (EoS) dense matter. In particular, neutron-matter EoS between 1 and 2 times saturation density ${n}_{0}\ensuremath{\approx}0.16\text{ }\text{ }{\mathrm{fm}}^{\ensuremath{-}3}$ constrained within 20%, given simulated data about 15 merger events. Using Fisher information methods, we combine...

We find that a class of models MeV-GeV dark matter in which interacts strongly can be constrained by the observation gravitational waves from neutron star mergers. Trace amounts matter, either produced during supernova or accreted later, alter structure stars and influence their tidal polarizability. focus on interacting exchange light vector gauge bosons couple to conserved charge. In these models, accumulated extend large radii enhance Gravitational detected first binary merger GW170817...

We find that sub-GeV neutrino portal bosons carry lepton number can condense inside a protoneutron star (newly born neutron star). These are produced copiously and form Bose-Einstein condensate for range of as yet unconstrained coupling strengths to neutrinos. The is superfluid with transport properties differ dramatically from those encountered in ordinary dense baryonic matter. discuss how this phase could alter the evolution stars comment on implications signals nucleosynthesis.

Motivated by the neutron lifetime puzzle, it is proposed that neutrons may decay into new states yet to be observed. We review star constraints on dark fermions carrying unit baryon number with masses around 939 MeV, and discuss interaction strengths required for particle. The possibility of decaying three investigated. While up six flavors quarks 313 MeV can compatible massive pulsars, any such exotic lighter than about 270 are excluded existence low-mass stars ∼1.2M⊙. Light in allowed mass...

The implications of perturbative QCD (PQCD) calculations on neutron stars are carefully examined. While PQCD above baryon chemical potential $\mu_B\sim2.4$ GeV demonstrate the ruling out a wide range star equations state (EOSs), these types constraints only affect most massive in vicinity Tolman-Oppenheimer-Volkoff (TOV) limit, resulting bounds EOSs that orthogonal to those from current or future astrophysical observations, even if observations near TOV limit made. Assuming constraining...

We show that the existence of massive neutron stars and asymptotic freedom QCD place robust upper bounds on lowest sound speed ultra-dense matter unattainable in stars. Our approach does not rely explicitly representing equation state density range $\sim 2-40 n_0$, require probabilistic interpretations. The limit decreases rapidly when maximum mass is greater than about $2.5M_\odot$. Discovery 3 M_\odot$ would strongly support first-order phase transitions at high baryon densities

I show that in addition to the well-known peak inside massive neutron stars, sound speed cold dense QCD matter likely exhibits another above star densities before it asymptotes $c_s=\sqrt{C_s}=\sqrt{1/3}$. Based on framework reported arxiv:2408.16738, this approach does not rely any assumption about ultra-dense realized nature. Current multimessenger observation of stars favors two-peak scenario with a Bayes factor $5.1_{-0.7}^{+0.9}$, where uncertainties are systematics due models inner...

We construct an efficient parameterization of the pure neutron-matter equation state (EoS) that incorporates uncertainties from both chiral effective field theory ($\chi$EFT) and phenomenological potential calculations. This yields a family EoSs including extending forms based purely on these two In combination with agnostic inner core EoS, this is used in Bayesian inference pipeline to obtain constraints e os parameters using multi-messenger observations neutron stars. specifically...

Dwarf neutron stars are stable twins of but with a maximum mass less than that stars. Their existence brings into concordance the seemingly conflicting information on size inferred from gravitational waves GW170817, NICER mission, and PREX-II experiment. distinctive characteristics lead to rich falsifiable predictions expected be tested in near future. If corroborated, dwarf would substantially improve our understanding QCD phase diagram offer valuable insights dark sector.