High Energy Physics - Phenomenology (hep-ph)

Abstract: In this paper we found the multiplicity distribution of the produced gluons in deep inelastic scattering at large $z=\ln\LbQ^2_s/Q^2\Rb\,\,\gg\,\,1$ where $ Q_s $ is the saturation momentum and $Q^2$ is the photon virtuality. It turns out that this distribution at large $n > \bar{n}$ almost reproduces the KNO scaling behaviour with the average number of gluons $ \bar{n} \propto \exp\Lb z^2/2 \kappa\Rb$, where $\kappa = 4.88 $ in the leading order of perturbative QCD. TheKNO function $\Psi\Lb \frac{n}{\bar{n}}\Rb = \exp\Lb -\,n/\bar{n}\Rb$. For $n < \bar{n}$ we found that $\sigma_n \propto\Big( z - \sqrt{2 \,\kappa\,\ln (n-1)}\Big)/(n-1)$. Such small $n$ determine the value of entropy of produced gluons $S_E = 0.3\, z^2/(2\,\kappa)$ at large $z$. The factor $0.3$ stems from the non-perturbative corrections that provide the correct behaviour of the saturation momentum at large $b$.

Abstract: We study the production of right-handed $W_R$ bosons and heavy neutrinos $N$ at a future 100 TeV high energy hadron collider in the context of Left-Right symmetry, including the effects of $W_L-W_R$ gauge-boson mixing. We estimate the collider reach for up to 3/ab integrated luminosity using a multi-binned sensitivity measure. In the Keung-Senjanovi\'c and missing energy channels, the 3$\sigma$ sensitivity extends up to $M_{W_R}=35$ and 37 TeV, respectively. We further clarify the interplay between the missing energy channel and the (expected) limits from neutrinoless double beta decay searches, Big Bang nucleosynthesis and dark matter.

Abstract: The spontaneous breakdown of an approximate symmetry implies that the spectrum of the theory contains approximately massless particles. The hidden symmetry very strongly constrains their masses. A numerical evaluation of these constraints on the lattice would allow a more precise determination of the quark mass ratios m_u:m_d:m_s and thereby reduce some of the uncertainties encountered in precision flavour physics.

Abstract: We present a new method for the reconstruction of rational functions that can significantly reduce the number of numerical samples required. The method works by exploiting all the independent linear relations among target functions. Subsequently, the explicit solutions of the functions can be efficiently obtained by solving the linear system. As a first application, we utilize the method to address various examples within the context of Feynman integrals reduction. These examples demonstrate that our method can substantially improve the computational efficiency, making it invaluable for future computations in particle physics.

Abstract: A direct discovery of the cosmic neutrino background would bring to a closure the searches for relic left-over radiation predicted by the Hot Big Bang cosmology. Recently, the KATRIN experiment put a limit on the local relic neutrino overdensity with respect to the cosmological predicted average value at $\eta \lesssim 10^{11}$ [Phys. Rev. Lett. 129, 011806 (2022)]. In this work, we first examine to what extent such values of $\eta$ are conceivable. We show that even under cavalier assumptions, a cosmic origin of $\eta \gtrsim 10^4$ seems out of reach (with the caveat of forming bound objects under a new force,) but find that a hypothetical local source of low-energy neutrinos could achieve $\eta \sim 10^{11}$. Second, when such values are considered, we point out that the experimental signature in KATRIN and other neutrino-capture experiments changes, contrary to what has hitherto been assumed. Our results are model-independent and maximally accommodating as they only assume the Pauli exclusion principle. As intermittent physics target in the quest for C$\nu$B detection, we identify an experimental sensitivity to $\eta \sim 10^4$ for which conceivable sources exist; to resolve the effect of a degenerate Fermi gas for such overdensity an energy resolution of 10 meV is required.

Abstract: We use the scattering method to calculate the gravitational wave from axions annihilation in the axion cloud formed by the superradiance process around the Kerr black hole. We consider axions annihilating to gravitons as a three-body decay process and then calculate the corresponding decay width. In this approach, we can simply obtain the radiation power of gravitational wave and give the analytical approximate result with the spin effects of the Kerr black hole. Our study can also provide a cross-check to the numerical results in the traditional method.

Abstract: Augmenting the improved chiral effective potential of the on-shell renormalized 2+1 flavour quark-meson (RQM) model with the Polyakov-loop potential that accounts for the deconfinement transition,~we get the Quantum Chromodynamics (QCD) like framework of the renormalized Polyakov quark-meson (RPQM) model.~When the divergent quark one-loop vacuum term is included in the effective potential of the quark-meson (QM) model,~its tree level parameters or the parameters fixed by the use of meson curvature masses,~become inconsistent as the curvature masses involve the self energy evaluations at zero momentum.~Using the modified minimal subtraction method,~the consistent chiral effective potential for the RQM model has been calculated after relating the counterterms in the on-shell (OS) scheme to those in the $\overline{\text{MS}}$ scheme and finding the relations between the renormalized parameters of both the schemes where the physical (pole) masses of the $\pi, K, \eta$ and $\eta^{\prime}$ pseudo-scalar mesons and the scalar $\sigma$ meson,~the pion and kaon decay constants,~have been put into the relation of the running couplings and mass parameter.~Using the RPQM model and the PQM Model with different forms for the Polyakov-loop potentials in the presence or the absence of the quark back-reaction,~we have computed and compared the effect of the consistent quark one-loop correction and the quark back-reaction on the scaled chiral order parameter,~the QCD phase diagrams and the different thermodynamic quantities.~The results have been compared with the 2+1 flavor lattice QCD data from the Wuppertal-Budapest collaboration \{JHEP 09,73(2010); PLB 730,99(2014)\} and the HotQCD collaboration \{PRD 90,094503(2014)\}.

Abstract: In general, resonances are obtained by the Breit-Wigner parameterization. However, it is not entirely appropriate to use this parameterization with near-threshold resonances such as the $Z_b(10610)$ and the $Z_b(10650)$, as Breit-Wigner does not contain the threshold effect. To eliminate this defect, a recently proposed alternative distribution, the Sill, is used to predict possible heavy quark spin symmetry partners of the $Z_b(10610)$ and the $Z_b(10650)$. With the Sill values of the $Z_b(10650)$ and the $Z_b(10610)$ states, assuming these exotics generate molecular states consisting of contact and a pion exchange potential, heavy quark spin symmetry partners are examined with $S$ and $D$-wave contributions. In the light of the Sill type resonance approach, all the partners are found as bound states.

Abstract: We have investigated the internal structure of the open- and hidden-charmed ($DD^*$/$\bar DD^*$) molecules in the unified framework. We first fit the experimental lineshape of the $T^+_{cc}$ state and extract the $DD^*$ interaction, from which the $T^+_{cc}$ is assumed to arise solely. Then we obtain the $D\bar{D}^*$ interaction by charge conjugation. Our results show that the $D\bar{D}^*$ interaction is attractive but insufficient to form $X(3872)$. Instead, its formation requires the crucial involvement of the coupled channel effect between the $D\bar D^*$ and $c\bar c$ components, although the $c\bar c$ accounts for approximately $1\%$ only. Besides $X(3872)$, we have obtained a higher-energy state around $3957.9$ MeV with a width of $16.7$ MeV, which may be a potential candidate for the $X(3940)$.In $J^{PC}=1^{+-}$ sector, we have found two resonances related to the iso-vector $Z_c$ and the iso-scalar $h_c(2P)$, respectively. Our combined study provides valuable insights into the nature of these $DD^*$/$D\bar D^*$ exotic states.

Abstract: We point out that the gauge-invariance of the subleading Lagrangian of soft-collinear effective theory is realised in an intricate way through momentum-conservation violating contributions. Although these terms are disregarded in diagrammatic calculations, the gauge invariance of any physical transition amplitude is preserved due to the soft equations of motion. When not working with gauge-invariant building blocks, individual manifestly gauge-invariant constituent terms in the Lagrangian may give rise to gauge-dependent matrix elements starting at $\mathcal{O}(\lambda^2)$. Implications for a gauge-invariant definition of radiative jet functions are discussed.