Of course, the photon, for example. Antiparticles differ from particles only in their internal charges, not their spacetime properties, such as mass and spin.

“Can a particle be its own antiparticle?”

- to answer this question it is necessary before to understand – first of all – what is “particle”, and further – what is “antiparticle”.

Mainstream physics really principally hasn’t scientific answer to the first question, and so to the second one; and the answer can be, and is, only in framework of the Shevchenko-Tokarevsky’s Planck scale informational physical model, 3 main papers are

“The Informational Conception and the Base of Physics”

https://www.researchgate.net/publication/354418793_The_Informational_Conception_and_the_Base_of_Physics

“The Informational Physical Model and Fundamental Problems in Physics”

https://www.researchgate.net/publication/367397025_The_Informational_Physical_Model_and_Fundamental_Problems_in_Physics , and

Planck scale “The Informational Model — Nuclear Force”

https://www.researchgate.net/publication/369357747_The_informational_model_-Nuclear_Force

In the model it is rigorously scientifically rationally shown that Matter’s ultimate base is/are binary reversible, and so at least 4D, fundamental logical elements [FLE], which compose the at least 4D dense FLE- lattice, and everything in Matter are some disturbances in the lattice.

The lattice is placed in corresponding Matter’s utmost universal fundamentally absolute, fundamentally flat, fundamentally continuous, and fundamentally “Cartesian”, [5]4D spacetime with metrics (cτ,X,Y,Z,ct), where the really specific space cτ-dimension in mainstream physics is the time dimension, while really the time dimension is ct-dimension in the metrics above.

Particles are specific disturbances in the lattice, and, since the main utmost universal “kinematical” parameters of FLE, i.e. FLE “size” and “FLE binary flip time” are Planck length, lP, and Planck time, tP; so all disturbances in lattice, including particles, always constantly move in the 4D space with metrics (cτ,X,Y,Z) only with 4D velocities that have identical absolute values be equal to the speed of light, c= lP/tP.

Disturbances in the lattice [besides the mediators of fundamental Nature forces] appear if some the lattice’s FLE is impacted with transmission to it some 4D space momentum P [bold means 4D vector]. If P is infinitesimal, it creates a 4D disturbance in lattice “a FLE flipping point” that propagates as sequential FLE-by-FLE flipping with the speed of light along a 4D straight line.

However if P isn’t infinitesimal, since any disturbance in lattice cannot propagate with speed more than the speed of light [more correctly with speed c√2, see the 1-st link, but that isn’t too essential], so FLEs in the FLE-flipping point start to precess, and so the FLE-flipping point’s trajectory in 4D space is corresponding 4D “helix”,

- while the corresponding cyclically repeating concrete certain FLE-sequences forms a cyclically running with frequency ω algorithms – which [the algorithms] are just particles, that have energies E=Pc=ћω.

The post is rather long already, so now

Cheers

A particle is a representation of the direct product of the Poincaré group and a compact group that describes its charges; an antiparticle differs from a particle by the action of the charge conjugation operator on the representation of the charges.

So a particle that is neutral under the group of charges is its own antiparticle.

So let’s continue [see SS post above]

The 4D space with [utmost universal “kinematical”] metrics (cτ,X,Y,Z) above consists of two types of specifically different dimensions – 3 XYZdimensions, that, as that C.F. von Weizsäcker rigorously had proven in first 1950s, make binary operations, in this case “FLE flips” be possible;

- and unique cτ- dimension, that makes binary operation “FLE reversible flip” be possible, what is necessary, as that Fredkin-Toffoly have shown in last 1960s, for the energy conservation law could act.

Correspondingly there exit two main types of particles – “S-particles” that are created by 3DXYZ space lines directed momentums, and “T-particles” that are created by momentums that are directed along cτ-axis.

Photons are S-particles, and so move only in the 3D space with the speeds of light;

T- particles, if are at rest in the absolute 3DXYZ space, move only in the cτ-dimension with the speed of light; and so if a T-particle is impacted by some 3D space momentum, at that (i) - the every T-particle “rest mass” is observed, and (ii) - the particle moves also in 3D space with some speed V, correspondingly its speed in cτ-dimension decreases in Lorentz factor.

Antiparticles are reversed , i.e. the same as corresponding particle algorithms, but that run with opposite command order, algorithms.

Correspondingly particles that are created by 3DXYZ momentums don’t use reversive option, and so are “own antiparticles”. That are, again, photons, which are some transformations of the fundamental Nature Electric force mediators, and gravitons, which are transformations of Gravity Force mediators.

In Matter at least 4 known now Forces act: Gravity, Weak, Electric, and Strong/Nuclear Forces [for what Matter’s spacetime metric is (cτ,X,Y,Z, g,w,e,s,ct); g,w,e,s dimensions correspond the Forces above] , which differ by their strength and action range, where only Gravity Force is completely symmetrical Force, and so in Matter everything attracts everything,

- while seems the rest 3 Forces aren’t symmetrical. At least that is evident for Electric Force – electron’s charge is “negative”, while the “electron’s algorithm’s that runs reversibly”, i.e. positron’s, charge is positive. At that at creation of new T-particles at interactions always pairs of “particle+ antiparticle” appear, which mostly annihilate with production eventually photons and neutrinos.

Correspondingly among possible T-particles [in now known a few hundreds zoo] there exists one fundamental, exclusion – Planck mass particles [or other T-particles that have only Gravity charge], which are T-particles, but, since they have only Gravity Force charge [“gravitational mass”], the directed and reverse algorithms are identical, and so these T-particle are own antiparticles. Just therefore Matter doesn’t contain antimatter [why? – see 2-nd link in the SS post above, section “Cosmology”].

More see the links in yesterday SS post above.

Cheers