arXiv subjects

Xin-Yu Du

Publications and source records attributed to Xin-Yu Du.

7 recordsLinked to original sources

arXiv2026

Pseudo-Dirac Inelastic Dark Matter in the Leptophobic $U(1)_B$ Model: Confronting the LUX-ZEPLIN High-Recoil Event with Collider Searches

Interpreting the $248$~keV nuclear-recoil candidate reported by LUX-ZEPLIN (LZ) as an endothermic transition needs two ingredients usually put in by hand: a stable dark state, and a coherent current that is purely off diagonal. Gauging baryon number supplies both. For the minimal dark charges $B(\chi_L)=-3/2$ and $B(\chi_R)=-9/2$, the scalars that generate the dark masses leave an exact residual parity $P=(-1)^{6B}$ stabilizing the lightest state, while the same Majorana masses make the vector current transition dominated as an identity rather than a choice. At $m_\chi=1$~TeV and $\delta=300$~keV the model is over-determined: the observed LZ interval, a leading-order relic estimate and the LHC dijet limit meet at the single perturbatively acceptable point $(M_{Z_B},g_B)\simeq(1.44~\mathrm{TeV},0.233)$. That point is allowed by currently existing searches but sits just below the trigger-level dijet boundary, so it is alive and not yet decided--and a re-run of that analysis on the Run-3 data at $\sqrt s=13.6$~TeV, already on tape, will exclude it or find it. Nor is the interpretation confined to that splitting: at $\delta=200$~keV, the same construction predicts a heavier mediator at comparable coupling, $M_{Z_B}\simeq2.4$-$3.0$~TeV with $g_B\simeq0.15$-$0.34$, a range the HL-LHC dijet program will probe.

hep-ph↗

arXiv2026

Probing the imaginary parts and their $q^2$ dependences for the tau $g-2$ and EDM

The $\tau$ anomalous magnetic dipole moment (MDM) $a_\tau = (g-2)_\tau/2$ and electric dipole moment (EDM) $d_\tau$, are precision probes of electroweak dynamics and possible new physics sources, yet both remain weakly constrained experimentally. Treated as generalized form factors, these quantities exhibit a generic $q^2$ dependence for an off-shell interacting photon. For timelike momentum transfer above the $\tau^+\tau^-$ threshold, $q^2 = s > 4m_\tau^2$, the form factors can acquire absorptive imaginary parts. We investigate how such a $q^2$ dependence and the associated imaginary parts are generated from two complementary perspectives: the model-independent Standard Model Effective Field Theory (SMEFT) and a UV-complete Two-Higgs-Doublet Model (2HDM). The effective framework reveals the intimate correlation between $a_\tau$ and $d_\tau$. New CP-violating interactions which generate a non-zero $d_{\tau}$, can also generically have non-zero contributions to $a_\tau$, thereby deeply linking their phenomenological studies. Within the 2HDM, we demonstrate that sizable imaginary parts and significant $q^2$ running can be generated at levels accessible by $e^+e^-$ colliders. Motivated by these features, we propose experimental methods to extract both the real and imaginary components of the dipole form factors. Utilizing these techniques, we show that Belle II and the Super Tau-Charm Facility (STCF) can improve current bounds on $a_\tau$ by more than one order of magnitude. Finally, we highlight that combining measurements across the distinct center-of-mass energies of Belle II and STCF provides a unique, previously unexplored avenue to explicitly obtain information about the $q^2$ evolution of these dipole form factors.

hep-ph↗

arXiv2025

Complex $\tau$ Electric Dipole Moment from GeV-Scale New Physics

Among the charged leptons, the $\tau$ electric dipole moment~($d_\tau$) is the least constrained. We show that the Im[$d_\tau$] imposes strong constraints on new physics that have yet to be discussed. Motivated in particular by the Super Tau-Charm Facility (STCF), which will provide a uniquely clean environment for precision $\tau$-physics, we study the momentum-transfer dependence of $d_\tau(q^2)$ and compare the projected sensitivities of STCF and Belle II. Our analysis shows that an axion-like coupling of the $\tau$ lepton can induce sizable real and imaginary components of the EDM. The predicted EDM values may approach the present experimental sensitivities, making them accessible to future measurements at Belle II and the STCF.

hep-ph↗

arXiv2024

Fundamental Tests of P and CP Symmetries Using Octet Baryons at the $J/ψ$ Threshold

We systematically investigate tests of the parity P and the combined parity and charge-conjugate CP symmetries from differential angular distributions of $J/ψ$ decaying into the lowest-lying baryon pairs at BESIII and the next-generation super tau-charm facilities (STCFs). Large corrections from $Z$ and $W$ exchange induced parity violating effects are found for $J/ψ$ decays with large logarithms resummed up to $\mathcal{O}(α_s)$. The parity-violating asymmetries on the production and the decay sides of $J/ψ$ are both estimated to be of $\mathcal{O}(10^{-4})$, thus barely observable with the 10 billion $J/ψ$ events currently collected at BESIII. Nevertheless, these asymmetries utilizing the current BESIII data already permit a measurement of the weak mixing angle with an absolute uncertainty $δs_w^2\approx{0.09}$, corresponding to the first determination of $s_w^2$ at the $J/ψ$ threshold. In the future, STCFs are estimated to improve this bound by a factor of $\sim\,20$ to $δs_w^2\approx{0.005}$ within one year based on luminosity rescaling. We also obtain the 95% confidence level upper bounds on the electric dipole moments of the octet baryons, which are of $\mathcal{O}(10^{-18})\,e{\rm\,cm}$ for BESIII and $\mathcal{O}(10^{-19})\,e{\rm\,cm}$ for STCFs. These bounds are improved by two to three orders of magnitude in comparison with the only existing one on $Λ$ from Fermilab. The method discussed in this work also paves a way for a first and direct measurement of the $Ξ$ and $Σ$ electric dipole moments.

hep-ph↗

arXiv2019

A ratio of many gamma functions and its properties with applications

In the paper, the authors establish an inequality involving exponential functions and sums, introduce a ratio of many gamma functions, discuss properties, including monotonicity, logarithmic convexity, (logarithmically) complete monotonicity, and the Bernstein function property, of the newly introduced ratio, and construct two inequalities of multinomial coefficients and multivariate beta functions.

math.CA↗

arXiv2018

Molecular Gas Toward the Gemini OB1 Molecular Cloud Complex II: CO Outflow Candidates with Possible WISE Associations

We present a large scale survey of CO outflows in the Gem OB1 molecular cloud complex and its surroundings using the Purple Mountain Observatory Delingha 13.7 m telescope. A total of 198 outflow candidates were identified over a large area ($\sim$ 58.5 square degrees), of which 193 are newly detected. Approximately 68% (134/198) are associated with the Gem OB1 molecular cloud complex, including clouds GGMC 1, GGMC 2, BFS 52, GGMC 3 and GGMC 4. Other regions studied are: Local Arm (Local Lynds, West Front), Swallow, Horn, and Remote cloud. Outflow candidates in GGMC 1, BFS 52, and Swallow are mainly located at ring-like or filamentary structures. To avoid excessive uncertainty in distant regions ($\gtrsim$ 3.8 kpc), we only estimated the physical parameters for clouds in the Gem OB1 molecular cloud complex and in the Local arm. In those clouds, the total kinetic energy and the energy injection rate of the identified outflow candidates are $\lesssim$ 1% and $\lesssim$ 3% of the turbulent energy and the turbulent dissipation rate of each cloud, indicating that the identified outflow candidates cannot provide enough energy to balance turbulence of their host cloud at the scale of the entire cloud (several pc to dozens of pc). The gravitational binding energy of each cloud is $\gtrsim$ 135 times the total kinetic energy of the identified outflow candidates within the corresponding cloud, indicating that the identified outflow candidates cannot cause major disruptions to the integrity of their host cloud at the scale of the entire cloud.

astro-ph.GA↗

arXiv2015

CO Core Candidates in the Gemini Molecular Cloud

We present observations of a 4 squared degree area toward the Gemini cloud obtained using J = 1-0 transitions of $^{12}$CO, $^{13}$CO and C$^{18}$O. No C$^{18}$O emission was detected. This region is composed of 36 core candidates of $^{13}$CO. These core candidates have a characteristic diameter of 0.25 pc, excitation temperatures of 7.9 K, line width of 0.54 km s$^{-1}$ and a mean mass of 1.4 M$_{\sun}$. They are likely to be starless core candidates, or transient structures, which probably disperse after $\sim$10$^6$ yr.

astro-ph.GA↗