Featured Researches

High Energy Physics Phenomenology

AW±polarization analyzer from Deep Neural Networks

In this paper, we train a Convolutional Neural Network to classify longitudinally and transversely polarized hadronicW±using the images of boostedW±jets as input. The images capture angular and energy information from the jet constituents that is faithful to properties of the original quark/anti-quarkW±decay products without the need for invasive substructure cuts. We find that the difference between the polarizations is too subtle for the network to be used as an event-by-event tagger. However, given an ensemble ofW±events with unknown polarization, the average network output from that ensemble can be used to extract the longitudinal fractionfL. We test the network on Standard Modelpp??W±Zevents and onpp??W±Zin the presence of dimension-6 operators that perturb the polarization composition.

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High Energy Physics Phenomenology

Adjoint SU(5) GUT model with ModularS4Symmetry

We study the textures of SM fermion mass matrices and their mixings in a supersymmetric adjoint SU(5) Grand Unified Theory with modularS4being the horizontal symmetry. The Yukawa entries of both quarks and leptons are expressed by modular forms with lower weights. Neutrino sector has an adjoint SU(5) representation 24 as matter superfield, which is a triplet ofS4. The effective light neutrino masses is generated through Type-III and Type-I seesaw mechanism. The only common complex parameter in both charged fermion and neutrino sectors is modulus?. Down-type quarks and charged leptons have the same joint effective operators with adjoint scalar in them, and their mass discrepancy in the same generation depends on Clebsch-Gordan factor. Especially for the first two generations the respective Clebsch-Gordan factors made the double Yukawa ratioydyμ/yeys=12, in excellent agreement with the experimental result. We reproduce proper CKM mixing parameters and all nine Yukawa eigenvalues of quarks and charged leptons. Neutrino masses and MNS parameters are also produced properly with normal ordering is preferred.

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High Energy Physics Phenomenology

Alice meets Boojums in neutron stars: vortices penetrating two-flavor quark-hadron continuity

Alice and Boojums are both representative characters created by Lewis Carroll. We show that they possibly meet in cores of rotating neutron stars. Recent studies of quark-hadron continuity suggest that neutron superfluid matter can connect smoothly to two-flavor symmetric quark matter at high densities. We study how this can be maintained in the presence of the vortices. In the neutron matter, quantized superfluid vortices arise. In the two-flavor dense quark matter, vortices carrying color magnetic fluxes together with fractionally quantized superfluid circulations appear as the most stable configuration, and we call these as the non-Abelian Alice strings. We show that three integer neutron superfluid vortices and three non-Abelian Alice strings of different color magnetic fluxes with total color flux canceled out are joined at a junction called a Boojum.

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High Energy Physics Phenomenology

Alternative method of generating gamma rays with orbital angular momentum

We propose a new method of generating gamma rays with orbital angular momentum (OAM). Accelerated partially-stripped ions are used as an energy up-converter. Irradiating an optical laser beam with OAM on ultrarelativistic ions, they are excited to a state of large angular momentum. Gamma rays with OAM are emitted in their deexcitation process. We examine the excitation cross section and deexcitation rate.

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High Energy Physics Phenomenology

An EFT toolbox for baryon and lepton number violating dinucleon to dilepton decays

In this paper we systematically consider the baryon (B) and lepton (L) number violating dinucleon to dilepton decays (pp????+????,pn????+ν¯??,nn??ν¯ν¯??) with?B=?L=??in the framework of effective field theory. We start by constructing a basis of dimension-12 (dim-12) operators mediating such processes in the low energy effective field theory (LEFT) below the electroweak scale. Then we consider their standard model effective field theory (SMEFT) completions upwards and their chiral realizations in baryon chiral perturbation theory (B?PT) downwards. We work to the first nontrivial orders in each effective field theory, collect along the way the matching conditions, and express the decay rates in terms of the Wilson coefficients associated with the dim-12 operators in SMEFT and the low energy constants pertinent to B?PT. We find the current experimental limits push the associated new physics scale larger than1??TeV, which is still accessible to the future collider searches. Through weak isospin symmetry, we find the current experimental limits on the partial lifetimes of transitionspp????+????,pn????+ν¯??imply stronger limits onnn??ν¯ν¯??than their existing lower bounds, which are improved by2??orders of magnitude. Furthermore, assuming charged mode transitions are also dominantly generated by the similar dim-12 SMEFT interactions, the experimental limits onpp??e+e+,e+μ+,μ+μ+lead to stronger limits onpn????+αν¯βwithα,β=e,μthan their existing bounds. Conversely, the same assumptions help us to set a lower bound on the lifetime of the experimentally unsearched modepp??e+?+from that ofpn??e+ν¯?, i.e.,???pp??e+?+???1034 yrs.

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High Energy Physics Phenomenology

An allowed window for heavy neutral leptons below the kaon mass

The extension of the Standard Model with two gauge-singlet Majorana fermions can simultaneously explain two beyond-the-Standard-model phenomena: neutrino masses and oscillations, as well as the origin of the matter-antimatter asymmetry in the Universe. The parameters of such a model are constrained by the neutrino oscillation data, direct accelerator searches, big bang nucleosynthesis, and requirement of successful baryogenesis. We show that the combination of all these constraints still leaves an allowed region in the parameter space below the kaon mass. This region can be probed by the further searches of NA62, DUNE, or SHiP experiments.

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High Energy Physics Phenomenology

An even lighter QCD axion

We explore whether the axion which solves the strong CP problem can naturally be much lighter than the canonical QCD axion. TheZNsymmetry proposed by Hook, withNmirror and degenerate worlds coexisting in Nature and linked by the axion field, is considered in terms of generic effective axion couplings. We show that the total potential is safely approximated by a single cosine in the largeNlimit, and we determine the analytical formula for the exponentially suppressed axion mass. The resulting universal enhancement of all axion interactions relative to those of the canonical QCD axion has a strong impact on the prospects of axion-like particle experiments such as ALPS II, IAXO and many others. The finite density axion potential is also analyzed and we show that theZNasymmetric background of high-density stellar environments sets already significant model-independent constraints:3?�N??7for an axion scalefa??.4?1015GeV, with tantalizing discovery prospects for any value offaand down toN??with future neutron star and gravitational wave data, down to the ultra-light mass region. In addition, two specific ultravioletZNcompletions are developed: a composite axion one and a KSVZ-like model with improved Peccei-Quinn quality.

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High Energy Physics Phenomenology

An improved light-cone harmonic oscillator model for the pionic leading-twist distribution amplitude

In this paper, we study the pion leading-twist distribution amplitude?2;?(x,μ)by improving the traditional light-cone harmonic oscillator model within the reconstruction of the function?2;?(x). In order to constraining the model parameters, we calculate its moments??ξn??2;?|μin the framework of QCD background field theory sum rule (BFTSR) up to10thorder. Considering the fact that the sum rule of the0thmoment??ξ0??2;?|μcannot be normalized, we suggest a more reasonable sum rule formula for??ξn??2;?|μ. Then, we obtain the values of??ξn??2;?|μ0withn=(2,4,6,8,10)at the initial scaleμ0=1 GeV. The first two moments are:??ξ2??2;?|μ0=0.271±0.013,??ξ4??2;?|μ0=0.138±0.010; and the corresponding Gegenbauer moments area2;?2(μ0)=0.206±0.038,a2;?4(μ0)=0.047±0.011, respectively. After fitting the moments??ξn??2;?|μ, we obtained the appropriate model parameters by using the least square method. The resultant behavior for twist-2 pion DA is more closely to the AdS/QCD and lattice result, but is narrower than that by Dyson-Schwinger equation. Furthermore, we calculate the pion-photon transition form factors (TFF) andB?�πTFF within light-cone sum rule approach, which are conform with experimental and theoretical results.

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High Energy Physics Phenomenology

Analysis of the boundaries of the quasi-elastic neutrino-nucleus cross section in the SuSAM* model

In this work we obtain the analytical expressions for the boundaries of the charged current quasi-elastic double differential cross section in terms of dimensionless energy and momentum transfers, for the Relativistic Fermi Gas (RFG) and the Super-Scaling approach with relativistic effective mass (SuSAM*) models, within the scaling formalism. In addition, this new double differential cross section in the scaling formalism has very good properties to be implemented in the Monte Carlo (MC) neutrino event generator, particularly because its peak is almost flat with the (anti)neutrino energy. This makes it especially well-suited for the event generation by the acceptance-rejection method usually used in the neutrino generators. Finally, we analyze the total charged current quasi-elastic (CCQE) cross section?(Eν)for both models and attribute the enhancement observed in the SuSAM* total cross section to the high-momentum components which are present, in a phenomenological way, in its scaling function, while these are absent in the RFG model.

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High Energy Physics Phenomenology

Analytical Spectrum of Nonlinear Thomson Scattering Including Radiation Reaction

Accelerated charges emit electromagnetic radiation and the consequent energy-momentum loss alters their trajectory. This phenomenon is known as radiation reaction and the Landau-Lifshitz (LL) equation is the classical equation of motion of the electron, which takes into account self-consistently radiation-reaction effects in the electron trajectory. By using the analytical solution of the LL equation in an arbitrary plane wave, we compute the analytical expression of the classical emission spectrum via nonlinear Thomson scattering including radiation-reaction effects. Both the angularly-resolved and the angularly-integrated spectra are reported, which represent the exact classical expressions of the spectra in the sense that neglected contributions are smaller than quantum effects. Also, we have obtained a phase-dependent expression of the electron dressed mass, which includes radiation-reaction effects. Finally, the corresponding spectra within the locally-constant field approximation have been derived.

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