{"title":"Neutron lifetime and dark decay of the neutron and hydrogen","authors":"Z. Berezhiani","doi":"10.31526/LHEP.1.2019.118 10.31526/LHEP.1.2019.118","DOIUrl":"https://doi.org/10.31526/LHEP.1.2019.118 10.31526/LHEP.1.2019.118","url":null,"abstract":"The neutron, besides its $beta$-decay $nto p ebarnu_e$, might have a new decay channel $nto n' X$ into mirror neutron $n'$, its nearly mass degenerate twin from parallel dark sector, and a massless boson $X$ which can be ordinary and mirror photons or some more exotic particle. Such an invisible decay could alleviate the tension between the neutron lifetimes measured in the beam and trap experiments. I discuss some phenomenological and astrophysical consequences of this scenario, which depends on the mass range of mirror neutron $n'$. Namely, the case $m_{n'} m_p + m_e$, then the decay $n'to pebar nu_e$ is allowed and $n'$ can represent an unstable dark matter component with rather large lifetime exceeding the age of the Universe. Nevertheless, this decay would produce substantial diffuse gamma background. The dark decay explanation of the lifetime puzzle, however, has a tension with the last experimental results measuring $beta$-asymmetry in the neutron decay.","PeriodicalId":36085,"journal":{"name":"Letters in High Energy Physics","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2018-12-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41794246","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"$U(1)_chi$ and Seesaw Dirac Neutrinos","authors":"E. Ma","doi":"10.31526/LHEP.1.2019.109","DOIUrl":"https://doi.org/10.31526/LHEP.1.2019.109","url":null,"abstract":"In the context of $SO(10) to SU(5)times U(1)chi$, it is shown how seesaw Dirac neutrinos \u0000may be obtained. In this framework, $U(1)$ lepton number is conserved, with which self-interacting dark matter with a light scalar dilepton mediator may be implemented. In \u0000addition, $U(1)$ baryon number may be broken to (−1)3B, thereby generating a baryonasymmetry of the Universe. The axionic solution to the strong CP problem may alsobe incorporated.","PeriodicalId":36085,"journal":{"name":"Letters in High Energy Physics","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2018-11-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47654270","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Collider signature of V_2 Leptoquark with b → s flavour observables","authors":"A. Biswas, Avirup Shaw, A. Swain","doi":"10.31526/LHEP.2.2019.126","DOIUrl":"https://doi.org/10.31526/LHEP.2.2019.126","url":null,"abstract":"The Leptoquark model has been instrumental in explaining the observed lepton flavour universality violating charged ($bto c$) and neutral ($bto s$) current anomalies that have been the cause for substantial excitement in particle physics recently. In this article we have studied the role of one (designated as $V_2^{frac 43}$) of the components of {boldmath${V}_2$} Vector Leptoquark doublet with electromagnetic charge $frac 43$ in explaining the neutral current ($bto s$) anomalies $R_{K^{(*)}}$ and $B_stomu^+mu^-$. Moreover, we have performed a thorough collider search for this $V_2^{frac 43}$ Leptoquark using $bbar{b} ell^+ ell^-$ ($ellequiv e, mu$) final state at the Large Hadron Collider. From our collider analysis we maximally exclude the mass of the $V_2^{frac 43}$ Leptoquark up to 2340 GeV at 95% confidence level for the 13 TeV Large Hadron Collider for an integrated luminosity of 3000 ${rm fb}^{-1}$. Furthermore, a significant portion of the allowed parameter space that is consistent with the neutral current ($bto s$) observables is excluded by collider analysis.","PeriodicalId":36085,"journal":{"name":"Letters in High Energy Physics","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2018-11-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48157446","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"The $tau$ Magnetic Dipole Moment at Future Lepton Colliders","authors":"J. Howard, A. Rajaraman, R. Riley, T. Tait","doi":"10.31526/LHEP.2.2019.113","DOIUrl":"https://doi.org/10.31526/LHEP.2.2019.113","url":null,"abstract":"The magnetic moment of the $tau$ lepton is an interesting quantity that is potentially sensitive to physics beyond the Standard Model. Electroweak gauge invariance implies that a heavy new physics contribution to it takes the form of an operator which involves the Higgs boson, implying that rare Higgs decays are able to probe the same physics as $a_tau$. We examine the prospects for rare Higgs decays at future high energy lepton (electron or muon) colliders, and find that such a project collecting a few ab$^{-1}$ would be able to advance our understanding of this physics by roughly a factor of 10 compared to the expected reach of the high luminosity LHC.","PeriodicalId":36085,"journal":{"name":"Letters in High Energy Physics","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2018-10-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41390589","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"$U(1)_{chi}$, Seesaw Dark Matter, and Higgs Decay","authors":"E. Ma","doi":"10.31526/LHEP.1.2019.103","DOIUrl":"https://doi.org/10.31526/LHEP.1.2019.103","url":null,"abstract":"It has recently been pointed out that the underlying symmetry of dark matter may well be $U(1)_chi$ (coming from $SO(10) to SU(5) times U(1)_chi$) with the dark parity of any given particle determined by $(-1)^{Q_chi+2j}$, where $Q_chi$ is its $U(1)_chi$ charge and $j$ its spin angular momentum. Armed with this new insight, previous simple models of dark matter are reinterpreted, and a novel idea is proposed that light seesaw dark matter exists in analogy to light neutrinos and is produced by the rare decay of the standard-model Higgs boson.","PeriodicalId":36085,"journal":{"name":"Letters in High Energy Physics","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2018-10-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42833720","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Evolution operator for time-dependent non-Hermitian Hami ltonians","authors":"B. Bagchi","doi":"10.31526/LHEP.3.2018.02","DOIUrl":"https://doi.org/10.31526/LHEP.3.2018.02","url":null,"abstract":"The evolution operator (U(t)) for a time-independent parity-time-symmetric systems is well studied in the literature. However, for the non-Hermitian time-dependent systems, a closed form expression for the evolution operator is not available. In this paper, we make use of a procedure, originally developed by A.R.P. Rau [Phys.Rev.Lett, 81, 4785-4789 (1998)], in the context of deriving the solution of Liuville-Bloch equations in the product form of exponential operators when time-dependent external elds are present, for the evaluation of (U(t)) in the interaction picture wherein the corresponding Hamiltonian is time-dependent and in general non-Hermitian. This amounts to a transformation of the whole scheme in terms of addressing a nonlinear Riccati equation the existence of whose solutions depends on the fulllment of a certain accompanying integrabilty condition.","PeriodicalId":36085,"journal":{"name":"Letters in High Energy Physics","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2018-09-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45657066","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A. Cabo, J. Suarez, D. Arrebato, F. Guzmán, J. Acosta
{"title":"Can the symmetry breaking in the SM be determined by the “second minimum” of the Higgs potential?","authors":"A. Cabo, J. Suarez, D. Arrebato, F. Guzmán, J. Acosta","doi":"10.31526/lhep.2.2019.98","DOIUrl":"https://doi.org/10.31526/lhep.2.2019.98","url":null,"abstract":"The possibility that the spontaneous symmetry breaking in the Standard Model (SM) may be generated by the Top-Higgs Yukawa interaction (which determines the so called \"second minimum\" in the SM) is examined. A former analysis is extended about a QCD action only including the Yukawa interaction of a single quark with a scalar field. We repeat the calculation of the two loop effective action of the model for the scalar field. A correction of the evaluation allowed choosing a strong coupling $alpha $($mu,Lambda_{QCD})=0.2254$ GeV at an intermediate scale $mu=11.63$ GeV, in order to fix the minimum of the potential at a scalar field determining $175$ GeV for the quark mass. A scalar field mass $m=44$ GeV is following, which is of the order than the experimental Higgs mass. The effects of considering a running with momenta coupling are studied. For this, the finite part of the two loop potential contribution determined by the strong coupling, was represented as a momentum integral. Next, substituting in this integral the experimental values of the running coupling, the potential curve became very similar to the one for constant coupling. This happened after simply assuming that the low momentum dependence of the coupling is \"saturated\" to a constant value being close to its lowest experimental value.","PeriodicalId":36085,"journal":{"name":"Letters in High Energy Physics","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2018-06-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44968907","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Invariant Tensors in Gauge Theories","authors":"Dillon Berger, J. Howard, A. Rajaraman","doi":"10.31526/lhep.2.2018.04","DOIUrl":"https://doi.org/10.31526/lhep.2.2018.04","url":null,"abstract":"Invariant tensors play an important role in gauge theories, for example, in dualities of N=1 gauge theories. However, for theories with fields in representations larger than the fundamental, the full set of invariant tensors is often difficult to construct. We present a new approach to the construction of these tensors, and use it to find the complete set of invariant tensors of a theory of SO(3) with fields in the symmetric tensor representation.","PeriodicalId":36085,"journal":{"name":"Letters in High Energy Physics","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2018-06-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47953201","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"An inverse seesaw model with $U(1)_R$ gauge symmetry","authors":"Takaaki Nomura, H. Okada","doi":"10.31526/LHEP.2.2018.01","DOIUrl":"https://doi.org/10.31526/LHEP.2.2018.01","url":null,"abstract":"We propose a natural realization of inverse seesaw model with right-handed and flavor dependent (U(1)) gauge symmetries, in which we formulate the neutrino mass matrix to reproduce current neutrino oscillation data in a general way. Also we study a possibility to provide predictions to the neutrino sector by imposing an additional flavor dependent (U(1)_{L_mu-L_tau}) gauge symmetry that also satisfies the gauge anomaly cancellation conditions associated with (U(1)_R). Then we analyze collider physics on an extra gauge boson and show a possibility of detection.","PeriodicalId":36085,"journal":{"name":"Letters in High Energy Physics","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2018-06-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44911306","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Quantum gravity: a quantum-first approach","authors":"S. Giddings","doi":"10.31526/LHEP.3.2018.01","DOIUrl":"https://doi.org/10.31526/LHEP.3.2018.01","url":null,"abstract":"A \"quantum-first\" approach to gravity is described, where rather than quantizing general relativity, one seeks to formulate the physics of gravity within a quantum-mechanical framework with suitably general postulates. Important guides are the need for appropriate mathematical structure on Hilbert space, and correspondence with general relativity and quantum field theory in weak-gravity situations. A basic physical question is that of \"Einstein separability:\" how to define mutually independent subsystems, e.g. through localization. Standard answers via tensor products or operator algebras conflict with properties of gravity, as is seen in the correspondence limit; this connects with discussions of \"soft hair.\" Instead, gravitational behavior suggests a networked Hilbert space structure. This structure plus unitarity provide important clues towards a quantum formulation of gravity.","PeriodicalId":36085,"journal":{"name":"Letters in High Energy Physics","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2018-05-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48489010","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}