Wed·Jul 28, 2021Wednesday·July 28, 2021

1. 01*

   JUNO's prospects for determining the neutrino mass ordering

   David V. Forero🇨🇴 · Stephen J. Parke🇺🇸 · Christoph A. Ternes🇮🇹 · Renata Zukanovich Funchal🇧🇷

   The flagship measurement of the JUNO experiment is the determination of the neutrino mass ordering. Here we revisit its prospects to make this determination by 2030, using the current global knowledge of the relevant neutrino parameters as well as current information on the reactor configuration and the critical parameters of the JUNO detector. We pay particular attention to the non-linear detector energy response. Using the measurement of ${\theta }_{13}$ from Daya Bay, but without information from other experiments, we estimate the probability of JUNO determining the neutrino mass ordering at $\ge$ 3$\sigma$ to be 31% by 2030. As this probability is particularly sensitive to the true values of the oscillation parameters, especially $\Delta m_{21}^2$, JUNO's improved measurements of ${\sin }^2{\theta }_{12}$, $\Delta m_{21}^2$ and $|\Delta m_{ee}^2|$, obtained after a couple of years of operation, will allow an updated estimate of the probability that JUNO alone can determine the neutrino mass ordering by the end of the decade. Combining JUNO's measurement of $|\Delta m_{ee}^2|$ with other experiments in a global fit will most likely lead to an earlier determination of the mass ordering.

   hep-phhep-exPRD(2021)·28 citations
2. 02*

   Displaced Higgs production in Type-III Seesaw at the LHC/FCC, MATHUSLA and Muon collider

   Chandrima Sen🇮🇳 · Priyotosh Bandyopadhyay🇮🇳 · Saunak Dutta🇮🇳 · Aleesha KT🇮🇳

   In this article, we explore the possibility of displaced Higgs production from the decays of the heavy fermions in the Type-III seesaw extension of the Standard Model at the LHC/FCC and the muon collider. The displaced heavy fermions and the Higgs boson can be traced back by measuring the displaced charged tracks of the charged leptons along with the $b$-jets. A very small Yukawa coupling can lead to two successive displaced decays which makes the phenomenology even more interesting. The prospects of the transverse and longitudinal displaced decay lengths are extensively studied in the context of the boost at the LHC/FCC. Due to the parton distribution function, the longitudinal boosts leads to larger displacement compared to the transverse one, which can reach MATHUSLA and beyond. The longitudinal measurements are indeed possible by the visible part of the finalstate, which captures the complete information about the longitudinal momenta. The comparative studies are made at the LHC/FCC with the centre of mass energies of 14, 27 and 100 TeV, respectively. A futuristic study of the muon collider where the collision happen in the centre of mass frame is analysed for centre of mass energies of 3.5, 14 and 30 TeV. Contrary to LHC/FCC, here the transverse momentum diverges, however, the maximum reach in both the direction are identical due to the constant total momentum in each collision. The reach of the Yukawa couplings and fermion masses are appraised for both the colliders. FCC at 100 TeV can probe a mass of 4.25 TeV and a lowest Yukawa coupling of $\mathcal{O}(5\times 10^{-11})$.

   hep-phEPJC(2022)·31 citations
3. 03*

   Lorentz violation in nucleon electromagnetic moments

   Javier Montaño-Domínguez🇲🇽 · Héctor Novales-Sánchez🇲🇽 · Mónica Salinas🇲🇽 · J. Jesús Toscano🇲🇽

   Yukawa couplings in the Lorentz- and $CPT$-violating Standard Model Extension (SME) induce quantum contributions to the electromagnetic moments of quarks, which are calculated in the present paper and then used to define contributions to electromagnetic moments of nucleons. High-sensitivity measurements of the proton and neutron electromagnetic moments then yield constrains on SME coefficients, reaching bounds as restrictive as $10^{-12}$. This approach notably grants access to SME effects from the second and third quark families.

   hep-phPRD(2022)·7 citations
4. 04*

   The Diphoton $q_T$ spectrum at N${}^3$LL${}^{\prime }$+NNLO

   Tobias Neumann🇺🇸

   We present a $q_T$-resummed calculation of diphoton production at order N${}^3$LL${}^{\prime }$+NNLO. To reach the primed level of accuracy we have implemented the recently published three-loop $\mathcal{O}({\alpha }_s^3)$ virtual corrections in the $q\bar{q}$ channel and the three-loop transverse momentum dependent beam functions and combined them with the existing infrastructure of CuTe-MCFM, a code performing resummation at order N${}^3$LL. While the primed predictions are parametrically not more accurate, one typically observes from lower orders and other processes that they are the dominant effect of the next order. We include in both the $q\bar{q}$ and loop-induced $gg$ channel the hard contributions consistently together at order ${\alpha }_s^3$ and find that the resummed $q\bar{q}$ channel without matching stabilizes indeed. Due to large matching corrections and large contributions and uncertainties from the $gg$ channel, the overall improvements are small though. We furthermore study the effect of hybrid-cone photon isolation and hard-scale choice on our fully matched results to describe the ATLAS 8 TeV data and find that the hybrid-cone isolation destroys agreement at small $q_T$.

   hep-phhep-exEPJC(2021)·28 citations
5. 05*

   Balancing Asymmetric Dark Matter with Baryon Asymmetry by Sphaleron Transitions

   Arnab Chaudhuri🇷🇺 · Maxim Yu. Khlopov🇷🇺

   The effect of the electroweak sphaleron transition in balance between baryon excess and and the excess of stable quarks of 4th generation is studied in this paper. Considering the non-violation of $SU(2)$ symmetry and the conservation of electroweak and new charges and quantum numbers of the new family, it makes possible sphaleron transitions between baryons, leptons and 4th family of leptons and quarks. In this paper, we have tried to established a possible definite relationship between the value and sign of the 4th family excess relative to baryon asymmetry. If $U$-type quarks are the lightest quarks of the 4th family and sphaleron transitions provide excessive $\bar{U}$ antiquarks, asymmetric dark matter in the form of dark atom bound state of ($\bar{U}\bar{U}\bar{U}$) with primordial He nuclei is balanced with baryon asymmetry.

   hep-phastro-ph.COPhys.Sc.Forum(2021)·1 citation
6. 06*

   Pre-supernova Ultra-light Axion-like Particles

   Kanji Mori🇯🇵 · Tomoya Takiwaki🇯🇵 · Kei Kotake🇯🇵

   We calculate the production of ultra-light axion-like particles (ALPs) in a nearby supernova progenitor. Once produced, ALPs escape from the star and a part of them is converted into photons during propagation in the Galactic magnetic field. It is found that the MeV photon flux that reaches Earth may be detectable by gamma ray telescopes for ALPs lighter than ~1 neV when Betelgeuse undergoes oxygen and silicon burning. The dependence of the gamma ray flux on the stellar mass is much smaller than the uncertainty that originates from the Galactic magnetic field. If ALPs are lighter than ~0.1 neV and the supernova progenitor is close enough to the Solar System, the gamma ray flux is insensitive to the distance d because the ALP-photon conversion probability is proportional to d^2. (Non-)detection of gamma rays from a supernova progenitor with next-generation gamma ray telescopes just after pre-supernova neutrino alerts would lead to an independent constraint on ALP parameters as stringent as a SN 1987A limit.

   hep-phastro-ph.HEastro-ph.SRPRD(2022)·6 citations
7. 07*

   Exclusive emissions of rho-mesons and the unintegrated gluon distribution

   Andrèe Dafne Bolognino🇮🇹 · Francesco Giovanni Celiberto🇮🇹 · Dmitry Yu. Ivanov🇷🇺 · Alessandro Papa🇮🇹

   Exclusive emissions of vector mesons in forward directions of rapidity offer us a faultless chance to probe the proton structure at small-$x$. A high-energy factorization formula is established within BFKL, given as the convolution of an impact factor depicting the forward-meson emission and of an unintegrated gluon distribution (UGD) driving the gluon evolution at small-$x$. As a nonperturbative quantity, the UGD is not well known and several models for it exist. We present recent progresses on the study of the exclusive forward $\rho$-meson leptoproduction at HERA and EIC energies, showing how osbervables sensitive to different polarization states of the $\rho$-particle act as discriminators for the existing UGD models.

   hep-phSciPost Phys.Proc.(2022)·38 citations
8. 08*

   Dark matter searches with mono-photon signature at future e${}^{+}$e${}^{-}$ colliders

   Jan Kalinowski🇵🇱 · Wojciech Kotlarski🇩🇪 · Krzysztof Mekala🇵🇱 · Pawel Sopicki🇵🇱 · Aleksander Filip Zarnecki🇵🇱

   As any e${}^{+}$e${}^{-}$ scattering process can be accompanied by a hard photon emission from the initial state radiation, the analysis of the energy spectrum and angular distributions of those photons can be used to search for hard processes with an invisible final state. Thus high energy e${}^{+}$e${}^{-}$ colliders offer a unique possibility for the most general search of Dark matter based on the mono-photon signature. We consider production of DM particles via a mediator at the International Linear Collider (ILC) and Compact Linear Collider (CLIC) experiments taking into account detector effects within the DELPHES fast simulation framework. Limits on the light DM production in a generic model are set for a wide range of mediator masses and widths. For mediator masses up to the centre-of-mass energy of the collider, results from the mono-photon analysis are more stringent than the limits expected from direct resonance searches in Standard Model decay channels.

   hep-phSciPost Phys.Proc.(2022)·4 citations
9. 09*

   Electroweak baryogenesis via bottom transport: complementarity between LHC and future lepton collider probes

   Tanmoy Modak🇩🇪 · Eibun Senaha🇻🇳

   We study the complementarity between the Large Hadron Collider (LHC) and future lepton colliders in probing electroweak baryogenesis induced by an additional bottom Yukawa coupling ${\rho }_{bb}$. The context is general two Higgs doublet model (g2HDM) where such additional bottom Yukawa coupling can account for the observed baryon asymmetry of the Universe if $\text{mbox}Im({\rho }_{bb})\gtrsim 0.058$. We find that LHC would probe the nominal $\text{mbox}Im({\rho }_{bb})$ required for baryogenesis to some extent via $bg\to bA\to bZh$ process if $300\text{mbox}GeV\lesssim m_A\lesssim 450$ GeV, where $A$ is the CP-odd scalar in g2HDM. We show that future electron positron collider such as International Linear Collider with $500$ GeV and 1 TeV collision energies may offer unique probe for the nominal $\text{mbox}Im({\rho }_{bb})$ via $e^{+}{e}^{-}\to Z^{\ast }\to AH$ process followed by $A,H\to b\bar{b}$ decays in four $b$-jets signature. For complementarity we also study the resonant diHiggs productions, which may give an insight into strong first-order electroweak phase transition, via $e^{+}{e}^{-}\to Z^{\ast }\to AH\to Ahh$ process in six $b$-jets signature. We find that 1 TeV collision energy with $\mathcal{O}(1){\text{ab}}^{-1}$ integrated luminosity could offer an ideal environment for the discovery.

   hep-phhep-exPLB(2021)·8 citations
10. 10*

    Weak scale right-handed neutrino as pseudo-Goldstone fermion of spontaneously broken $U(1{)}_{L_{\mu }-L_{\tau }}$

    Anjan S. Joshipura🇮🇳 · Ketan M. Patel🇮🇳

    Possibility of a Right-Handed (RH) neutrino being a Goldstone fermion of a spontaneously broken global $U(1)$ symmetry in a supersymmetric theory is considered. This fermion obtains mass from the supergravity effects leading to a RH neutrino at the electroweak scale with a mass similar to the gravitino mass. A prototype model realizing this scenario contains just three gauge singlet superfields needed for the type I seesaw mechanism. Masses of the other two neutrinos are determined by the $U(1)$ breaking scale which too can be around the electroweak scale. Light neutrinos obtain their masses in this scenario through (a) mixing with the RH neutrinos (type I seesaw), (b) mixing with neutralinos ($R$-parity breaking), (c) indirectly through mixing of the RH neutrinos with neutralinos, and (d) radiative corrections. All these contributions are described by the same set of a small number of underlying parameters and provide a very constrained and predictive framework for the neutrino masses which is investigated in detail for various choices of $U(1)$ symmetries. It is found that flavour independent $U(1)$ symmetries cannot describe neutrino masses if the soft supersymmetry breaking terms are flavour universal and one needs to consider flavour dependent symmetries. Considering a particular example of $L_{\mu }-L_{\tau }$ symmetry, it is shown that viable neutrino masses and mixing can be obtained without introducing any flavour violation in the soft sector. The leptonic couplings of Majoron are worked out in the model and shown to be consistent with various laboratory, astrophysical and cosmological constraints. The neutrino data allows sizeable couplings between the RH neutrinos and Higgsinos which can be used to probe the pseudo-Goldstone fermion at colliders through its displaced decay vertex.

    hep-phJHEP(2021)·1 citation
11. 11*

    Probing PeV scale SUSY-breaking with Satellite Galaxies and Primordial Gravitational Waves

    Gongjun Choi🇨🇳 · Ryusuke Jinno🇩🇪 · Tsutomu T. Yanagida🇨🇳

    We study an inevitable cosmological consequence in PeV scale SUSY-breaking scenarios. We focus on the SUSY-breaking scale corresponding to the gravitino mass $m_{3/2}=100\mathrm{eV}-1\mathrm{keV}$. We argue that the presence of an early matter-dominated era and the resulting entropy production are requisite for the Universe with this gravitino mass. We infer the model-independent minimum amount of the entropy production $\Delta$ by requiring that the number of dwarf satellite galaxies $N_{\mathrm{sat}}$ in the Milky Way exceed the currently observed value, i.e. $N_{\mathrm{sat}}\gtrsim 63$. This entropy production is inevitably imprinted on the primordial gravitational waves (pGWs) produced during the inflationary era. We study how the information on the value of $\Delta$ and the time of entropy production are encoded in the pGW spectrum ${\Omega }_{\mathrm{GW}}$. If the future GW surveys observe a suppression feature in the pGW spectrum for the frequency range $\mathcal{O}(10^{-10})\mathrm{Hz}\lesssim f_{\mathrm{GW}}\lesssim \mathcal{O}(10^{-5})\mathrm{Hz}$, it works as a smoking gun for PeV SUSY-breaking scenarios. Even if they do not, our study can be used to rule out all such scenarios.

    hep-phastro-ph.COPRD(2021)·6 citations
12. 12*

    Axion-like particle oscillations

    Francesca Chadha-Day🇬🇧

    String theory compactifications may generate many light axion-like particles (ALPs) with weak couplings to electromagnetism. In general, a large number of ALPs may exist, with a linear combination having a potentially observable coupling to electromagnetism. The basis in which only one ALP couples to electromagnetism is in general misaligned with the mass basis. This leads to mixing between the `electromagnetic' ALP and a number of `hidden' ALPs that do not interact directly with the photon. The process is analagous to neutrino oscillations. I will discuss the phenomenological consequences of this mixing for astrophysical ALP signals, in particular showing that it may significantly reduce the predicted signal in experiments such as the CERN Axion Solar Telescope.

    hep-phJCAP(2022)·27 citations
13. 13*

    Spinning No-Scale $\mathcal{F}$-$SU$(5) in the Right Direction

    Tianjun Li🇨🇳 · James A. Maxin🇺🇸 · Dimitri V. Nanopoulos🇺🇸

    The Fermi National Accelerator Laboratory (FNAL) recently announced confirmation of the Brookhaven National Lab (BNL) measurements of the $g-2$ of the muon that uncovered a discrepancy with the theoretically calculated Standard Model value. We suggest an explanation for the combined BNL+FNAL 4.2$\sigma$ deviation within the supersymmetric grand unification theory (GUT) model No-Scale $\mathcal{F}$-$SU(5)$ supplemented with a string derived TeV-scale extra $10+\overline{10}$ vector-like multiplet and charged vector-like singlet $(XE,X{E}^c)$, dubbed flippons. We introduced these vector-like particles into No-Scale Flipped $SU(5)$ many years ago, and as a result, the renormalization group equation (RGE) running was immediately shaped to produce a distinctive and rather beneficial two-stage gauge coupling unification process to avoid the Landau pole and lift unification to the string scale, in addition to contributing through 1-loop to the light Higgs boson mass. The flippons have long stood ready to tackle another challenge, and now do so yet again, where the charged vector-like "lepton"/singlet couples with the muon, the supersymmetric down-type Higgs $H_d$, and a singlet $S$, using a chirality flip to easily accommodate the muonic $g-2$ discrepancy in No-Scale $\mathcal{F}$-$SU(5)$. Considering the phenomenological success of this string derived model over the prior 11 years that remains accommodative of all presently available LHC limits plus all other experimental constraints, including no fine-tuning, and the fact that for the first time a Starobinsky-like inflationary model consistent with all cosmological data was derived from superstring theory in No-Scale Flipped $SU(5)$, we believe it is imperative to reconcile the BNL+FNAL developments within the model space.

    hep-phhep-exEPJC(2021)·9 citations
14. 14*

    A model of light pseudoscalar dark matter

    Shreyashi Chakdar🇺🇸 · Dilip Kumar Ghosh🇮🇳 · P. Q. Hung🇺🇸 · Najimuddin Khan🇮🇳 · Dibyendu Nanda🇮🇳

    The EW-${\nu }_R$ model was constructed in order to provide a seesaw scenario operating at the Electroweak scale ${\Lambda }_{EW}\sim 246$ GeV, keeping the same SM gauge structure. In this model, right-handed neutrinos are non-sterile and have masses of the order of ${\Lambda }_{EW}$. They can be searched for at the LHC along with heavy mirror quarks and leptons, the lightest of which have large decay lengths. The seesaw mechanism requires the existence of a complex scalar which is singlet under the SM gauge group. The imaginary part of this complex scalar denoted by $A_s^0$ is proposed to be the sub-MeV dark matter candidate in this manuscript. We find that the sub-MeV scalar can serve as a viable non-thermal feebly interacting massive particle (FIMP)-DM candidate. This $A_s^0$ can be a naturally light sub-MeV DM candidate due to its nature as a pseudo-Nambu-Goldstone (PNG) boson in the model. We show that the well-studied freeze out mechanism falls short in this particular framework producing DM overabundance. We identify that the freeze in mechanism produce the correct order of relic density for the sub-MeV DM candidate satisfying all applicable constraints. We then discuss the DM parameter space allowed by the current bounds from the direct and indirect searches for this sub-MeV DM. This model has a very rich scalar sector, consistent with various experimental constraints, predicts a $\sim 125$ GeV scalar with the SM Higgs characteristics satisfying the current LHC Higgs boson data.

    hep-phNPB(2024)·3 citations
15. 15*

    Reinterpreting the ATLAS bounds on heavy neutral leptons in a realistic neutrino oscillation model

    Jean-Loup Tastet🇩🇰 · Oleg Ruchayskiy🇩🇰 · Inar Timiryasov🇨🇭

    Heavy neutral leptons (HNLs) are hypothetical particles, motivated in the first place by their ability to explain neutrino oscillations. Experimental searches for HNLs are typically conducted under the assumption of a single HNL mixing with a single neutrino flavor. However, the resulting exclusion limits may not directly constrain the corresponding mixing angles in realistic HNL models -- those which can explain neutrino oscillations. The reinterpretation of the results of these experimental searches turns out to be a non-trivial task, that requires significant knowledge of the details of the experiment. In this work, we perform a reinterpretation of the latest ATLAS search for HNLs decaying promptly to a tri-lepton final state. We show that in a realistic model with two HNLs, the actual limits can vary by several orders of magnitude depending on the free parameters of the model. Marginalizing over the unknown model parameters leads to an exclusion limit on the total mixing angle which can be up to 3 orders of magnitude weaker than the limits reported in arXiv:1905.09787. This demonstrates that the reinterpretation of results from experimental searches is a necessary step to obtain meaningful limits on realistic models. We detail a few steps that can be taken by experimental collaborations in order to simplify the reuse of their results.

    hep-phhep-exJHEP(2021)·69 citations
16. 16*

    Endpoint Relations for Baryons

    Gudrun Hiller🇩🇪 · Roman Zwicky🇬🇧

    Following our earlier work we establish kinematic endpoint relations for baryon decays using the Wigner-Eckart theorem and apply them to $\frac{1}{2}\to \frac{1}{2}$ and $\frac{1}{2}\to \frac{3}{2}$ baryon transitions. We provide angular distributions at the kinematic endpoint which hold for the generic $d=6$ model-independent effective Hamiltonian. Moreover, we explicitly verify the endpoint relations using an explicit form factor parametrisation and clarify constraints on helicity based form factors to evidence endpoint relations. Our results provide guidance for phenomenological parameterisations, consistency checks for theory computations and experiment. Results are applicable to ongoing and future new physics searches at LHCb, BES III and Belle II with rare semileptonic-, dineutrino-and charged-modes, which include ${\Lambda }_b\to {\Lambda }^{(\ast )}\ell \ell ,{\Lambda }_b\to {\Lambda }^{(\ast )}\nu \nu$, ${\Omega }_b\to \Omega \ell \ell$, ${\Lambda }_c\to p\ell \ell$, $\Sigma \to p\ell \ell$ and ${\Lambda }_b\to {\Lambda }_c^{(\ast )}\ell \nu$

    hep-phhep-exhep-latJHEP(2021)·37 citations
17. 17*

    Direct Detection of Light Dark Matter from Evaporating Primordial Black Holes

    Roberta Calabrese🇮🇹 · Marco Chianese🇮🇹 · Damiano F.G. Fiorillo🇮🇹 · Ninetta Saviano🇮🇹

    The direct detection of sub-GeV dark matter interacting with nucleons is hampered by the low recoil energies induced by scatterings in the detectors. This experimental difficulty is avoided in the scenario of boosted dark matter where a component of dark matter particles is endowed with large kinetic energies. In this Letter, we point out that the current evaporation of primordial black holes with masses from $10^{14}$ to $10^{16}$ g is a source of boosted light dark matter with energies of tens to hundreds of MeV. Focusing on the XENON1T experiment, we show that these relativistic dark matter particles could give rise to a signal orders of magnitude larger than the present upper bounds. Therefore, we are able to significantly constrain the combined parameter space of primordial black holes and sub-GeV dark matter. In the presence of primordial black holes with a mass of $10^{15}\mathrm{g}$ and an abundance compatible with present bounds, the limits on DM-nucleon cross-section are improved by four orders of magnitude.

    hep-phastro-ph.COhep-exhep-thPRD(2022)·49 citations
18. 18*

    Renormalization group improved implications of semileptonic operators in SMEFT

    Jacky Kumar🇩🇪

    We study implications of the four-fermion semileptonic operators at the low-energy and at electroweak (EW) scale in the framework of Standard Model Effective Field Theory (SMEFT). We show how the renormalization group (RG) running effects can play an important role in probing the \emph{generic flavour structure} of such operators. It is shown that at the 1-loop level, through RG running, depending upon the flavour structure, these operators can give rise to sizable effects at low energy in the electroweak precision (EWP) observables, the leptonic, quark, as well as the $Z$ boson flavour violating decays. To this end, we isolate the phenomenological relevant terms in the full anomalous dimension matrices (ADMs) and discuss the impact of the QED+QCD running in the Weak effective field theory (WET) and the SMEFT running due to gauge and Yukawa interactions on the dim-4 and dim-6 operators at the low energy. Considering all the relevant processes, we derive lower bounds on the new physics (NP) scale $\Lambda$ for each semileptonic operator, keeping a generic flavour structure. In addition, we also report the allowed ranges for the Wilson coefficients at a fixed value of $\Lambda =3$ TeV.

    hep-phhep-exJHEP(2022)·18 citations
19. 19*

    Measurement of Bell-type inequalities and quantum entanglement from $\Lambda$-hyperon spin correlations at high energy colliders

    Wenjie Gong🇺🇸 · Ganesh Parida🇺🇸 · Zhoudunming Tu🇺🇸 · Raju Venugopalan🇺🇸

    Spin correlations of $\Lambda$-hyperons embedded in the QCD strings formed in high energy collider experiments provide unique insight into their locality and entanglement features. We show from general considerations that while the Clauser-Horne-Shimony-Holt inequality is less stringent for such states, they provide a benchmark for quantum-to-classical transitions induced by varying i) the associated hadron multiplicity, ii) the spin of nucleons, iii) the separation in rapidity between pairs, and iv) the kinematic regimes accessed. These studies also enable the extraction of quantitative measures of quantum entanglement. We first explore such questions within a simple model of a QCD string composed of singlets of two partial distinguishable fermion flavors and compare analytical results to those obtained on quantum hardware. We further discuss a class of spin Hamiltonians that model the dynamics of $\Lambda$ spin correlations. Prospects for extracting quantum features of QCD strings from hyperon measurements at current and future colliders are outlined.

    hep-phnucl-exnucl-thquant-phPRD(2022)·91 citations
20. 20*

    Probing for New Physics with Rare Charm Baryon (${\Lambda }_c$, ${\Xi }_c$, ${\Omega }_c$) Decays

    Marcel Golz🇩🇪 · Gudrun Hiller🇩🇪 · Tom Magorsch🇩🇪

    We analyze rare charm baryon decays within the standard model and beyond. We identify all null test observables in unpolarized ${\Lambda }_c\to p{\ell }^{+}{\ell }^{-}$, $\ell =e,\mu$ decays, and study the new physics sensitivities. We find that the longitudinal dilepton polarization fraction $F_L$ is sensitive to electromagnetic dipole couplings $C_7^{(\prime )}$, and to the right-handed 4-fermion vector coupling $C_9^{\prime }$. The forward-backward asymmetry, $A_{\mathrm{FB}}$, due to the GIM-suppression a standard model null test already, probes the left-handed axialvector 4-fermion coupling $C_{10}$; its CP-asymmetry, $A_{\mathrm{FB}}^{\mathrm{CP}}$, probes CP-violating phases in $C_{10}$. Physics beyond the standard model can induce branching ratios of dineutrino modes ${\Lambda }_c\to p\nu \bar{\nu }$ up to a few times $10^{-5}$, and one order of magnitude smaller if lepton flavor universality is assumed, while standard model rates are negligible. Charged lepton flavor violation allows for striking signals into $e^{\pm }{\mu }^{\mp }$ final states, up to $10^{-6}$ branching ratios model-independently, and up to order $10^{-8}$ in leptoquark models. Related three-body baryon decays ${\Xi }_c\to \Sigma \ell \ell$, ${\Xi }_c\to \Lambda \ell \ell$ and ${\Omega }_c\to \Xi \ell \ell$ offer similar opportunities to test the standard model with $|\Delta c|=|\Delta u|=1$ transitions.

    hep-phhep-exJHEP(2021)·31 citations
21. 21*

    Sensitivity of KM3NeT to Violation of Equivalence Principle

    Marco Chianese🇮🇹 · Damiano F. G. Fiorillo🇮🇹 · Gianpiero Mangano🇮🇹 · Gennaro Miele🇮🇹 · Stefano Morisi🇮🇹 · Ofelia Pisanti🇮🇹

    The symmetry of the theory of relativity under diffeomorphisms strongly depends on the equivalence principle. Violation of Equivalence Principle (VEP) can be tested by looking for deviations from the standard framework of neutrino oscillations. In recent works, it has been shown that strong constraints on the VEP parameter space can be placed by means of the atmospheric neutrinos observed by the IceCube neutrino telescope. In this paper, we focus on the KM3NeT neutrino telescope and perform a forecast analysis to assess its capacity to probe VEP. Most importantly, we examine the crucial role played by systematic uncertainties affecting the neutrino observations. We find that KM3NeT will constrain VEP parameters times the local gravitational potential at the level of $10^{-27}$. Due to the systematic-dominated regime, independent analyses from different neutrino telescopes are fundamental for robustly testing the equivalence principle.

    hep-phastro-ph.HEgr-qchep-ex+1Symmetry(2021)·3 citations
22. 22*

    IceCube constraints on Violation of Equivalence Principle

    Damiano F. G. Fiorillo🇮🇹

    Among the information provided by high energy neutrinos, a promising possibility is to analyze the effects of a Violation of Equivalence Principle (VEP) on neutrino oscillations. We analyze the IceCube data on atmospheric neutrino fluxes under the assumption of a VEP and obtain updated constraints on the parameter space with the benchmark choice that neutrinos with different masses couple with different strengths to the gravitational field. In this case we find that the VEP parameters times the local gravitational potential at Earth can be constrained at the level of $10^{-27}$. We show that the constraints from atmospheric neutrinos strongly depend on the assumption that the neutrino eigenstates interacting diagonally with the gravitational field coincide with the mass eigenstates, which is not a priori justified: this is particularly clear in the case that the basis of diagonal gravitational interaction coincide with the flavor basis, which cannot be constrained by the observation of atmospheric neutrinos. Finally, we quantitatively study the effect of a VEP on the flavor composition of the astrophysical neutrinos, stressing again the interplay with the basis in which the VEP is diagonal: we find that for some choices of such basis the flavor ratio measured by IceCube can significantly change.

    hep-phPoS(2021)·0 citations
23. 23*

    Unified thermal model for photohadronic neutrino production in astrophysical sources

    Damiano F. G. Fiorillo🇮🇹

    Astrophysical neutrino fluxes are often modeled as power laws of the energy. This is reasonable in the case of hadronic sources, but it does not capture the behavior in photohadronic sources, where the spectrum depends on the properties of the target photons on which protons collide. This limits the possibility of a unified treatment of different sources. In order to overcome this difficulty, we model the target photons by a blackbody spectrum. This model is sufficiently flexible to reproduce neutrino fluxes from known photohadronic sources; we apply it to study the sensitivity of Dense Neutrino Arrays, Neutrino Telescopes and Neutrino Radio Arrays to photohadronic sources. We also classify the flavor composition of the neutrino spectrum in terms of the parameter space. We discuss the interplay with the experiments, studying the changes in the track-to-shower ratio induced by different flavor compositions, both within and outside the region of the Glashow resonance.

    hep-phastro-ph.HEPoS(2021)·0 citations
24. 24*

    Ultra high-energy cosmic rays from beyond the Greisen-Zatsepin-Kuz'min horizon

    Ellis R. Owen🇹🇼 · Qin Han🇨🇳 · Kinwah Wu🇬🇧 · Y. X. Jane Yap🇹🇼 · Pooja Surajbali🇩🇪

    Ultra-high-energy (UHE) cosmic rays (CRs) of energies $\sim (10^{18}-10^{20})\mathrm{eV}$, accelerated in violent astrophysical environments, interact with cosmic background radiation fields via photo-hadronic processes, leading to strong attenuation. Typically, the Universe would become `opaque' to UHE CRs after several tens of Mpc, setting the boundary of the Greisen-Zatsepin-Kuz'min (GZK) horizon. In this work, we investigate the contribution of sources beyond the conventional GZK horizon to the UHE CR flux observed on Earth, when photo-spallation of the heavy nuclear CRs is taken into account. We demonstrate this contribution is substantial, despite the strong attenuation of UHE CRs. A significant consequence is the emergence of an isotropic background component in the observed flux of UHE CRs, coexisting with the anisotropic foreground component that are associated with nearby sources. Multi-particle CR horizons, which evolve over redshift, are determined by the CR nuclear composition. Thus, they are dependent on the source populations and source evolutionary histories.

    ↳ astro-ph.HEastro-ph.GAhep-phApJ(2021)·4 citations
25. 25*

    Top-quark mass determination in the optimised threshold scan

    Kacper Nowak🇵🇱 · Aleksander Filip Zarnecki🇵🇱

    One of the important goals at the future e${}^{+}$e${}^{-}$ colliders is to measure the top-quark mass and width in a scan of the pair production threshold. Presented in this work is the most general approach to the top-quark mass determination from the threshold scan at CLIC, with all relevant model parameters and selected systematic uncertainties included in the fit procedure. In the baseline scan scenario the top-quark mass can be extracted with precision of the order of 30 to 40 MeV, already for 100 fb${}^{-1}$ of data collected at the threshold. We present the optimisation procedure based on the genetic algorithm with which the statistical uncertainty of the mass measurement can be reduced by about 20%.

    ↳ hep-exhep-phSciPost Phys.Proc.(2022)·1 citation
26. 26*

    Stochastic inflation at all order in slow-roll parameters: foundations

    Diego Cruces🇪🇸 · Cristiano Germani🇪🇸

    In this paper we develop the formalism for the stochastic approach to inflation at all order in slow-roll parameters. This is done by including the momentum and Hamiltonian constraints into the stochastic equations. We then specialise to the widely used Starobinski approximation where interactions between IR and UV modes are neglected. We show that, whenever this approximation holds, no significant deviations are observed when comparing the two-point correlation functions (power spectrum) calculated with stochastic methods, to the ones calculated with the QFT approach to linear theory. As a byproduct, we argue that: a) the approaches based on the Starobinski approximation, generically, do not capture any loop effects of the quantum scalar-gravity system; b) correlations functions can only be calculated in the linear theory regimes, thus, no non-perturbative statistics can be extracted within this approximation, as commonly claimed.

    ↳ gr-qcastro-ph.COhep-phhep-thPRD(2022)·45 citations
27. 27*

    On the order of the QCD chiral phase transition for different numbers of quark flavours

    Francesca Cuteri🇩🇪 · Owe Philipsen🇩🇪 · Alessandro Sciarra🇩🇪

    The nature of the QCD chiral phase transition in the limit of vanishing quark masses has remained elusive for a long time, since it cannot be simulated directly on the lattice and is strongly cutoff-dependent. We report on a comprehensive ongoing study using unimproved staggered fermions with $N_{\text{f}}\in [2,8]$ mass-degenerate flavours on $N_{\tau }\in \{4,6,8\}$ lattices, in which we locate the chiral critical surface separating regions with first-order transitions from crossover regions in the bare parameter space of the lattice theory. Employing the fact that it terminates in a tricritical line, this surface can be extrapolated to the chiral limit using tricritical scaling with known exponents. Knowing the order of the transitions in the lattice parameter space, conclusions for approaching the continuum chiral limit in the proper order can be drawn. While a narrow first-order region cannot be ruled out, we find initial evidence consistent with a second-order chiral transition in all massless theories with $N_{\text{f}}\le 6$, and possibly up to the onset of the conformal window at $9\lesssim N_{\text{f}}^{\ast }\lesssim 12$. A reanalysis of already published $\mathcal{O}(a)$-improved $N_{\text{f}}=3$ Wilson data on $N_{\tau }\in [4,12]$ is also consistent with tricritical scaling, and the associated change from first to second-order on the way to the continuum chiral limit. We discuss a modified Columbia plot and a phase diagram for many-flavour QCD that reflect these possible features.

    ↳ hep-lathep-phnucl-thJHEP(2021)·130 citations
28. 28*

    Twist-3 partonic distributions from lattice QCD

    Shohini Bhattacharya🇺🇸 · Krzysztof Cichy🇵🇱 · Martha Constantinou🇺🇸 · Andreas Metz🇺🇸 · Aurora Scapellato🇺🇸 · Fernanda Steffens🇩🇪

    Twist-3 partonic distributions contain important information that characterizes nucleon's structure. In this work, we show our lattice exploration of the twist-3 PDFs $g_T(x)$, and $h_L(x)$. We also present our preliminary results on the twist-3 GPD ${\tilde{G}}_2(x)$. We use the quasi-distribution approach to connect the lattice-extracted matrix elements, renormalized in the RI/MOM scheme, to light-cone distributions, applying the matching procedure that we developed in parallel. We also calculate the twist-2 counterparts of $g_T(x)$ and $h_L(x)$, i.e. $g_1(x)$, and $h_1(x)$, and test the Wandzura-Wilczek approximation.

    ↳ hep-lathep-phSciPost Phys.Proc.(2022)·8 citations
29. 29*

    The \texttau{} challenge at FCC-ee

    Mogens Dam🇩🇰

    At FCC-ee, about $1.7\times 10^{11}$ \mbox{Z $\to$ \texttau${}^{+}$\texttau${}^{-}$} events will be produced. This high statistics in the clean e${}^{+}$e${}^{-}$ environment opens the possibility of much improved determinations of \texttau-lepton properties and, via the measurement of the \texttau\ polarisation, of the neutral-current couplings of electrons and $\tau$s. Improved measurements of \texttau-lepton properties -- lifetime, leptonic branching fractions, and mass -- allow important tests of lepton universality. The experimental challenge is to match as far as possible statistical uncertainties generally at the $10^{-5}$ level. This applies in particular to the lifetime measurement, which is derived from the \mbox{2.2-mm} \texttau\ average flight distance, and for the branching fraction and polarisation measurements, where the cross-channel contamination is of particular concern. These issues raise strict detector requirements, in particular, on the accuracy of the construction and alignment of the vertex detector and of the precise calorimetric separation and measurement of photons and \textpi${}^0$s in the collimated \texttau\ decay topologies.

    ↳ hep-exhep-ph2 citations
30. 30*

    Neutrino mass matrices from localization in M-theory on $G_2$ orbifold

    Eric Gonzalez🇺🇸 · Gordon Kane🇺🇸 · Khoa Nguyen🇺🇸

    M-theory compactified on a $G_2$ manifold with resolved $E_8$ singularity is a promising candidate for a unified theory. The experimentally observed masses of quarks and charged leptons put a restriction on the moduli of the $G_2$ manifold. These moduli in turn uniquely determine the Dirac interactions of the neutrinos. In the paper, we explicitly compute the Dirac terms for neutrino mass matrix using the moduli from a localized model with resolved $E_8$ singularities on a $G_2$ manifold. This is a novel approach as the Dirac terms are not assumed but derived from the structure of quarks' and charged leptons' masses. Using known mass splittings and mixing angles of neutrinos, we show the acceptable region for Majorana terms. We also analyse the theoretical region for Majorana terms induced from the expectation values of right handed neutrinos through the Kolda-Martin mechanism. The intersection of the two regions indicates a restriction on neutrino masses. In particular, the lightest neutrino must have small but non-zero mass. Moreover, this also puts constraints on possible Majorana contributions from Kähler potential and superpotential, which can be traced down to a restriction on the geometry.We conclude that the masses of the two heavier light neutrinos are about $0.05\text{ eV}$ and $0.009\text{ eV}$ ($0.05\text{ eV}$ and $0.05\text{ eV}$)) for normal (inverted) hierarchy. In both hierarchies, we predict the light neutrinos are mostly Dirac type. Hence neutrino-less double-beta decay will be small. This is a testable result in a near future. Some bounds on heavy neutrinos are also derived.

    ↳ hep-thhep-phPRD(2022)·2 citations
31. 31*

    Symmetry of Cosmological Observables, and a High Hubble Constant as an Indicator of a Mirror World Dark Sector

    Francis-Yan Cyr-Racine🇺🇸 · Fei Ge🇺🇸 · Lloyd Knox🇺🇸

    We find that a uniform scaling of the gravitational free-fall rates and photon-electron scattering rate leaves most dimensionless cosmological observables nearly invariant. This result opens up a new approach to reconciling cosmic microwave background and large-scale structure observations with high values of the Hubble constant $H_0$: Find a cosmological model in which the scaling transformation can be realized without violating any measurements of quantities not protected by the symmetry. A "mirror world" dark sector allows for effective scaling of the gravitational free-fall rates while respecting the measured mean photon density today. Further model building might bring consistency with the two constraints not yet satisfied: the inferred primordial abundances of deuterium and helium.

    ↳ astro-ph.COhep-phPRL(2022)·95 citations
32. 32*

    Rigorous Bounds on Light-by-Light Scattering

    Johan Henriksson🇮🇹 · Brian McPeak🇮🇹 · Francesco Russo🇮🇹 · Alessandro Vichi🇮🇹

    We bound EFT coefficients appearing in $2\to 2$ photon scattering amplitudes in four dimensions. After reviewing unitarity and positivity conditions in this context, we use dispersion relations and crossing symmetry to compute sum rules and null constraints. This allows us to derive new rigorous bounds on operators with four, six, and eight derivatives, including two-sided bounds on their ratios. Comparing with a number of partial UV completions, we find that some of our bounds are saturated by the amplitudes that arise from integrating out a massive scalar or axion, while others suggest the existence of unknown amplitudes.

    ↳ hep-thhep-phJHEP(2022)·93 citations
33. 33*

    Probing Ultralight Bosons with Compact Eccentric Binaries

    Boye Su🇨🇳 · Zhong-Zhi Xianyu🇨🇳 · Xingyu Zhang🇨🇳

    Ultralight bosons can be abundantly produced through superradiance process by a spinning black hole and form a bound state with hydrogen-like spectrum. We show that such a "gravitational atom" typically possesses anomalously large mass quadrupole and leads to significant orbital precession when it forms an eccentric binary with a second compact object. Dynamically formed black hole binaries or pulsar-black hole binaries are typically eccentric during their early inspirals. We show that the large orbital precession can generate distinct and observable signature in their gravitational wave or pulsar timing signals.

    ↳ gr-qcastro-ph.HEhep-phApJ(2021)·21 citations

* Reconstructed cohort: no mailing for this day survives in the archive. Papers are grouped by their submission times and arXiv's announcement cut-off, assuming announcement without delay; positions follow identifier order. Validated at ~91% exact-day agreement against the archived era.