High Energy Physics - Phenomenology (hep-ph)

Abstract: This paper studies the quantum corrections to the Higgs inflation model in the context of the Einstein-Cartan (E-C) gravity in the large-$ N $ limit with $N$ being the number of real scalar components in Higgs. Recently, it is realized that the Higgs inflation in the E-C formalism smoothly connects those in the metric and the Palatini formalisms in the presence of a non-minimal coupling between the Higgs fields and the Nieh-Yan term. This motivates us to investigate the quantum corrections to the E-C Higgs inflation and to clarify how the Ricci curvature squared $ R^2 $ induced by the quantum corrections succeeds in Ultraviolet (UV)-extending the Higgs inflation in metric formalism while it fails in the Palatini case. We show that a generalized $ R^2 $-term required for the renormalization in the E-C formalism induces a new scalar degree of freedom (DoF), the scalaron, which gradually decouples with the system due to its increasing mass as approaching the Palatini limit. The presence of the scalaron extends the UV cutoff at vacuum of the original model except for the parameter space close to the Palatini limit. This UV-extension is expected to solve the strong coupling problem that may exist during (p)reheating in the absence of the scalaron.

Abstract: We explore a scenario of high scale supersymmetry where all supersymmetric particles except gauginos stay at a high energy scale $M_{\rm SUSY}$ which is much larger than the reheating temperature $T_\text{RH}$. The dark matter is dominated by bino component with mass around the electroweak scale and the observed relic abundance is mainly generated by the freeze-in process during the early universe. Considering the various constraints, we identify two available scenarios in which the supersymmetric sector at an energy scale below $T_\text{RH}$ consists of: a) bino; b) bino and wino. Typically, for a bino mass around 0.1-1 TeV and a wino mass around 2 TeV, we find that $M_{\rm SUSY}$ should be around $10^{12-14}$ GeV with $T_\text{RH}$ around $10^{4-6}$ GeV.

Abstract: The inverted pendulum is a mechanical system with a rapidly oscillating pivot point. Using techniques similar in spirit to the methodology of effective field theories, we derive an effective Lagrangian that allows for the systematic computation of corrections to the so-called Kapitza equation. The derivation of the effective potential of the system requires non-trivial matching conditions, which need to be determined order by order in the power-counting of the problem. The convergence behavior of the series is investigated on the basis of high-order results obtained by this method.

Abstract: Data-driving determination of the new properties of elastic scattering at small angles on the basis on all existing experimental data for $d\sigma/dt$ of $pp$ and $p\bar{p}$ at $\sqrt{s} \geq 540$ GeV allows us to obtain the main characteristics of the nonstandard terms of the elastic scattering amplitude. It was shown that the oscillation term has a different sign for $pp$ and $p\bar{p}$ reactions; hence, it is part of the Odderon amplitude. The energy dependence of the oscillation term and the term with an extremely large slope is determined. The period of the oscillation term agrees with the scaling properties predicted by the Auberson - Kinoshita - Martin (AKM) theorem. The high quality quantitative description of all data at $\sqrt{s} \geq 540$ GeV in the framework of the HEGS model supports such a phenomenon which can be connected with peripheral hadron interaction.

Abstract: The origin of tiny neutrino mass is an unsolved puzzle leading to a variety of phenomenological aspects beyond the Standard Model (BSM). Among several interesting attempts, $U(1)$ gauge extension of Standard Model (SM) is a simple and interesting set-up where the so-called seesaw mechanism is incarnated by the addition of three generations of right-handed neutrinos followed by the breaking of $U(1)$ and electroweak symmetries. Such scenarios are anomaly free in nature appearing with a neutral BSM gauge boson ($Z^\prime$). In addition to that, there comes another open question regarding the existence of a non-luminous, hitherto unidentified object called Dark Matter (DM) originating from the measurement of its relic density. To explore properties of $Z^\prime$, we focus on chiral and flavored scenarios where $Z^\prime-$neutrinos interaction could be probed in the context of cosmic explosions like gamma-ray burst (GRB221009A, so far the highest energy), blazar (TXS 0506+056) and Active galaxy (NGC1068) respectively. The neutrino antineutrino annihilation produces electron-positron pair which could energize GRB through energy deposition. Taking the highest energy GRB under consideration and estimating the energy deposition rates we constrain $Z^\prime$ mass $(M_{Z^\prime})$ and the additional $U(1)$ coupling $(g_X)$ for chiral and flavored scenarios in the Schwarzchild, Hartle-Thorne and modified gravity frameworks. On the other hand, adding viable and alternative DM candidates in these models we study neutrino-DM scattering mediated by $Z^\prime$ in the $t-$ channel and estimate constraints on $g_X-M_{Z^\prime}$ plane using observed data of high energy neutrinos from cosmic blazar and active galaxy at the IceCube experiment. We compare our results with bounds obtained from different scattering, beam-dump and $g-2$ experiments.

Abstract: The $S$ matrix rephasing invariance is one of the fundamental principles of quantum mechanics that originates in its probabilistic interpretation. For a given $S$ matrix which describes neutrino oscillation, one can define the two different rephased amplitudes $S_{\alpha \beta}^{ \text{Reph-1} } \equiv e^{ i (\lambda_{1} / 2E) x} S_{\alpha \beta}$ and $S_{\alpha \beta}^{ \text{Reph-2} } \equiv e^{ i (\lambda_{2} / 2E) x} S_{\alpha \beta}$, which are physically equivalent to each other, where $\lambda_{k} / 2E$ denotes the energy eigenvalue of the $k$-th mass eigenstate. The leading-order terms in $S_{\alpha \beta}^{ \text{Reph-1} }$ and $S_{\alpha \beta}^{ \text{Reph-2} }$ describe, respectively, the 1-3 and 2-3 level crossings around the atmospheric-scale resonance. We point out that the transformation of the reparametrization (Rep) symmetry obtained with ``Symmetry Finder'' maps $S_{\alpha \beta}^{ \text{Reph-1} }$ to $S_{\alpha \beta}^{ \text{Reph-2} }$, and vice versa, providing a local and manifest realization of the $S$ matrix rephasing invariance by the Rep symmetry. It strongly suggests a quantum mechanical nature of the Rep symmetry. An all-order treatment of the intimate relationships between the Rep symmetry and $S$ matrix rephasing invariance is attempted.

Abstract: We compute the $\sin(2\phi-\phi_{s})$ azimuthal asymmetry in the pion-nucleon induced Drell-Yan process within transverse momentum dependent factorization. We employ the holographic light-front pion wave functions to calculate its leading-twist transverse momentum dependent parton distributions (TMDs). The Boer-Mulders TMD of the pion is then convoluted with the transversity TMD of the proton evaluated in a light-front quark-diquark model constructed with the wave functions predicted by the soft-wall AdS/QCD to obtain the azimuthal asymmetry in the Drell-Yan process. The gluon rescattering is pivotal to predict nonzero pion Boer-Mulders TMD. We investigate the utility of a nonperturbative SU$(3)$ gluon rescattering kernel going beyond the usual approximation of perturbative U$(1)$ gluons. The holographic light-front QCD approach provides a powerful tool for exploring the role of nonperturbative QCD effects in the Drell-Yan process and may help to guide future experimental measurements.

Abstract: We discuss heavy quark diffusion and radiation in an intermediate-momentum regime where finite mass effects can be significant. Diffusion processes are described in the Fokker-Planck approximation for soft momentum transfer, while radiative ones are taken into account by nearly collinear gluon emission from a single scattering in the Boltzmann equation. We also consider radiative corrections to the transverse momentum diffusion coefficient, which are $\mathcal{O}(g^2)$ suppressed than the leading-order diffusion coefficient but logarithmically enhanced. Numerical results show that the heavy quark distribution function depends on the energy loss mechanism so that the momentum dependence of suppression is distinguishable. Employing the heavy quark diffusion coefficient constrained by lattice QCD data, we estimate the nuclear modification factor which exhibits a transition from diffusion at low momentum to radiation at high momentum. The significance of radiative effects at intermediate momentum depends on the diffusion coefficient and running coupling constant.

Abstract: This paper presents a theoretical study on the production of the heavy-flavour decay lepton (HFL) in high-energy nuclear collisions at the LHC. The pp-baseline is calculated by the FONLL program, which matches the next-to-leading order pQCD calculation with the next-to-leading-log large-$p_T$ resummation. The in-medium propagation of heavy quarks is driven by the modified Langevin equations, which consider both the elastic and inelastic partonic interactions. We propose a method to separate the respective influence of the five factors, such as pp-spectra, the cold nuclear matter (CNM) effects, in-medium energy loss (E-loss), fragmentation functions (FFs), and decay channels, which may contribute to the larger $R_{AA}$ of HFL $\leftarrow b$ compared to that of HFL $\leftarrow c$ in nucleus-nucleus collisions. Based on quantitative analysis, we demonstrate that different decay channels of charm- and bottom-hadrons play an important role at $p_T<$5 GeV, while the mass-dependent E-loss dominates the higher $p_T$ region. It is also found that the influences of the CNM effects and FFs are insignificant, while different initial pp-spectra of charm and bottom quarks have a considerable impact at $p_T>$ 3 GeV. Furthermore, we explore the path-length dependence of jet quenching by comparing the HFL $R_{AA}$ in two different collision systems. Our investigations show smaller HFL $R_{AA}$ in Pb+Pb than that in Xe+Xe within the same centrality bin, which is consistent with the ALICE data. The longer propagation time and more effective energy loss of heavy quarks in Pb+Pb collisions play critical roles in the stronger yield suppression of the HFL compared to that in Xe+Xe. In addition, we observe a scaling behaviour of the HFL $R_{AA}$ in Xe+Xe and Pb+Pb collisions.

Abstract: Indirect detection is one of the most powerful methods to search for annihilating dark matter. In this work, we investigate the impact of non-perturbative effects in the indirect detection of dark matter. For this purpose we utilize a minimal model consisting of a fermionic dark matter candidate in the TeV mass range that interacts via scalar- and pseudo-scalar interactions with a massive scalar mediator mixing with the Higgs. The scalar interaction induces an attractive Yukawa potential between dark matter particles, such that annihilations are Sommerfeld enhanced, and bound states can form. These non-perturbative effects are systematically dealt with (potential) non-relativistic effective field theories and we derive the relevant cross sections for dark matter. We discuss their impact on the relic density and indirect detection. Annihilations in dwarf galaxies and the Galactic Center require special care and we derive generalized $J$-factors for these objects that account for the non-trivial velocity dependence of the cross sections in our model. We use limits on the gamma-ray flux based on Fermi-LAT observations and limits on the rate of exotic energy injection from Planck to derive bounds on the parameter space of the model. Finally, we estimate the impact that future limits from the Cherenkov Telescope Array are expected to have on the model.

Abstract: We consider the relic density and positivity bounds for freeze-in scalar dark matter with general Higgs-portal interactions up to dimension-8 operators. When dimension-4 and dimension-6 Higgs-portal interactions are proportional to mass squares for Higgs or scalar dark matter in certain microscopic models such as massive graviton, radion or general metric couplings with conformal and disconformal modes, we can take the dimension-8 derivative Higgs-portal interactions to be dominant for determining the relic density via the 2-to-2 thermal scattering of the Higgs fields after reheating. We show that there is a wide parameter space for explaining the correct relic density from the freeze-in mechanism and the positivity bounds can curb out the dimension-8 derivative Higgs-portal interactions nontrivially in the presence of the similar dimension-8 self-interactions for Higgs and dark matter.

Abstract: The latest FermiLab muon $g-2$ result shows a $5\sigma$ discrepancy with a ``widely advertised" Standard Model prediction. We consider a supersymmetric $SU(4)_c \times SU(2)_L \times SU(2)_R$ model in which this discrepancy is resolved by including contributions to muon $g-2$ from a relatively light SUSY sector. A variety of realistic coannihilation scenarios can reproduce the observed dark matter relic abundance. With a significantly reduced discrepancy, of order $1 \sigma$ or less, the Higgsino-like dark matter solutions are also viable. We provide benchmark points for these solutions that will be probed in the direct detection dark matter experiments and collider searches.

Abstract: This paper which is part of a series, is devoted to several technical issues. In the first part of the paper, we discuss the usual wavefunctions in the CM frame for baryons, by clarifying the representations of the three-quark permutation group $S_3$. We extend the analysis for up to five ``spinors" with $\rho,\lambda$-symmetry, and derive explicitly the totally symmetric wavefunctions modulo color. They are explicitly used to describe the excited nucleons $N^*$ states, in the P- and D-shell. We also show how to use symbolic operations in Mathematica, in spin-tensor notations to make explicit these states. For the S- and P-shells, the totally antisymmetric wavefunctions are given, and the pertinent matrix elements for the spin-dependent operators calculated, including the mixing between states with different total spin $S$. In the second part of the paper we turn to the light front wavefunctions, with an emphasis on the longitudinal wavefunctions, with a novel basis set. We also discuss their symmetries under permutations, and select the proper combinations for the transverse and longitudinal excitations for $N^*$ on the light front.

Abstract: The computational cost associated with reducing tensor integrals to scalar integrals using the Passarino-Veltman method is dominated by the diagonalisation of large systems of equations. These systems of equations are sized according to the number of independent tensor elements that can be constructed using the metric and external momenta. In this article, we present a closed-form solution of this diagonalisation problem in arbitrary tensor integrals. We employ a basis of tensors whose building blocks are the external momentum vectors and a metric tensor transverse to the space of external momenta. The scalar integral coefficients of the basis tensors are obtained by mapping the basis elements to the elements of an orthogonaldual basis. This mapping is succinctly expressed through a formula that resembles the ordering of operators in Wick's theorem. Finally, we provide examples demonstrating the application of our tensor reduction formula to Feynman diagrams in QCD $2 \to 2$ scattering processes, specifically up to three loops.

Abstract: We explore the possibility that the initial transverse momentum distribution of unpolarized and polarized partons within unpolarized protons, both with and without the anisotropy of unpolarized hadrons produced in the fragmentation of outgoing partons, could lead to the observed azimuthal anisotropy of high transverse momentum (high-$p_T$) hadrons produced in high energy proton-proton ($p$-$p$) or proton-ion ($p$-$A$) collisions. Including simple Gaussian forms for transverse momentum dependent parton distribution functions (PDF) and fragmentation functions, and assuming an $A^{1/3}$ enhancement of a PDF in $p$-$Pb$ collisions, we show that the observed anisotropy, with \emph{no modification} to the angle integrated spectra ($R_{pA}\!=1$) for 5 GeV $\lesssim p_T\lesssim 50$ GeV, can be straightforwardly understood as arising from a few processes dominated by gluon-gluon to gluon-gluon scattering.